Article

Recovery of sediments after cessation of marine fish farm production

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Abstract

Following cessation of fish production at a fish farm site in Loch Cretan, Scotland, a study of the recovery of the benthic environment was undertaken. Sediment samples for macrofauna and geochemical parameters (redox potential, organic carbon, oxygen flux) were collected over a period of 15 months from three stations following a gradient of impact from the former fish farm site. The data collected were analysed by a combination of uni-and multivariate statistical methods. The macrobenthic community at the two stations furthest from the fish cage site showed signs of recovery with time in terms of indicator species, number of species and abundance, being, however, still moderately to slightly disturbed at the end of this study. At the station nearest to the former fish cage site, recovery of the macrobenthic community was also evident, but this station was still highly impacted 15 months after fish production ceased, with opportunistic species dominant. Fifteen months after fallowing, highly reduced conditions were still persistent in subsurface sediments at the stations on the periphery of the former fish cage site. Bulk sediment organic carbon, although an indicator of a spatial gradient, was not found to be a significant indicator of recovery. Combinations of different environmental parameters appear to affect different stages of benthic recovery with sediment oxygen uptake as the main observed parameter conditioning early stages of macrobenthic succession. (C) 2004 Elsevier B.V. All rights reserved.

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... The combination of deteriorating physical and physiological conditions can lead to the replacement of the macro-fauna with one dominated by small opportunistic species, such as Capitella sp, Mediomastus fragilis and Malacocerus fuliginosus, species which are able to tolerate hypoxic conditions (Pereira et al., 2004;Tomassetti and Porrello, 2005;Bannister et al., 2014;Keeley et al., 2019). Under appropriate conditions such opportunistic organisms may flourish in huge numbers and their abundance is thus often used as an indicator of organic enrichment (Hargrave et al., 2008;SEPA, 2019a). ...
... However, they did note that macrofaunal diversity and species richness were still suppressed at the end of the fallow period, echoing the earlier findings of Macleod et al. (2006). Other researchers have reported longer recovery times, but conclusions can vary depending on how 'recovery' is defined (Lumb, 1989;Johannessen et al., 1994;McGhie et al., 2000;Pohle et al., 2001;Pereira et al., 2004). ...
... However, the relationship between organic enrichment and changes to the benthic community is often not as straightforward as the model may suggest (Brown et al., 1987;Weston, 1990;Hargrave et al., 1993;Sowles et al., 1994;Cromey et al., 1998;Chamberlain, 2002;Wilding et al., 2012;Keeley et al., 2013b). Based on sampling at a redundant farm site in Loch Creran, Pereira et al., (2004) reported that the percentage of organic carbon in the sediment was not a good indicator of temporal changes in the recovering macrobenthic community. The authors suggested that this might be in part due to changes in the fraction of labile carbon in the total pool of organic carbon. ...
Technical Report
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PLEASE NOTE REVISION 2 OF THE REPORT WHICH CORRECTS SOME ERRORS PRESENT IN THE ORIGINAL VERSION. Organic waste from open cage fish farms can negatively impact the benthos if the quantities of settling material exceed the natural assimilative capacity of the seabed. The amounts of total organic material which are allowed to be released are thus regulated in most countries where open-cage fish farming takes place. In Scotland, limits on settling organic waste are one of the main factors determining the maximum fish biomass permitted at a farm site. Computer models of the dispersal of total organic waste to the seabed have become an important tool in both initial site licencing, but also continued site monitoring. The main organic waste dispersal model used in Scotland is DEPOMOD. Originally developed in the late 1990s this model has gone through several upgrades, the latest version being NewDEPOMOD. The original model was developed and calibrated for relatively sheltered, low dispersal sea-loch sites with muddy seabed, where the model’s predictive capability has proven to be generally high. However, many newer fish farms have been developed in more dispersive sites. Despite NewDEPOMOD incorporating a relatively sophisticated waste resuspension sub-model, problems have been encountered with accurately predicting the benthic footprint of fish farm organic waste at these more dispersive sites. The main aim of the INCREASE project was to try and improve our understanding of why these predictive problems are occurring and to suggest future work to address any issues identified. The problem of predicting safe organic loading to the seabed can be broken down into four broad process steps (i) the amount of feed used and its assimilation efficiency by the fish (ii) the settlement of waste material from the cages through the water column to reach the seabed (iii) the potential for resuspension and movement of waste material from its initial settlement site (iv) the biologically facilitated breakdown of the accumulated organic waste material on the seabed. The studies undertaken in the INCREASE project are concerned with process (iii). Some additional research was conducted on sulphides measurement (in relation to process iv) as a potential tool for assessing benthic impacts, under a separately funded project, NAMAQI. However, both projects conducted research at the same farms, so the results are presented as a combined report, avoiding the need to repeat large parts of the introduction, materials and methods etc. The research comprised:- 1. Conducting a comprehensive literature review on 1.1. modelling waste dispersal from cage finfish farms, especially in higher energy sites. 1.2. marine sediment diagenesis and sediment chemistry in relation to sulphide production under and adjacent to fish farms. 2. Undertaking field studies at three sites located over sandy, as opposed to soft mud, sediments to 2.1. attempt to quantify organic waste deposition rates to the seabed directly. 2.2. model the waste deposition using NewDEPOMOD. 2.3. compare the modelled and observed organic carbon deposition rates to investigate problems encountered when using NewDEPOMOD for more dispersive sites. 3. Additional work was undertaken at two farm sites to evaluate whether quantifying sulphides in the sediment may be a useful tool for rapid monitoring of benthic impacts by comparison with the Infaunal Quality Index (IQI). This component of the program also drew on experience from Canada where sulphide measurements are used as part of the routine regulatory process. 4. Production of recommendations for future studies and potential changes to NewDEPOMOD which might improve modelling of total organic waste dispersal at more dispersive locations. 5. Production of recommendations on whether sediment sulphide measurements could be a practical and useful tool for monitoring fish farm benthic impacts in Scotland. The main conclusions from the literature review under INCREASE were that problems with modelling waste dispersal at higher energy sites have been noted in several other published studies. In addition, a limited number of flume experiments have been conducted which suggest that the critical erosion threshold for organic waste is strongly related to the coarseness of the sediments as well as the level of organic loading. The main conclusions from the literature review under NAMAQI were that there is relatively good understanding of the diagenetic processes and the relationships between sediment oxic state, organic carbon loading, free sulphide production by microbial action and subsequent impacts on benthic macrofauna. Several diagenetic process models are available, but these have been developed as research tools rather than for operational use by regulators and fish farm managers. Published data, mainly from Canada but also some from Scotland, suggests that while the extremes of macrofauna-benthic state may be predictable from free sulphide concentrations, intermediate levels of sulphides result in a wide range of benthic community responses. Fieldwork was undertaken at three Cooke Aquaculture farms located in the Orkney Islands, namely Bay of Vady, Qaunterness and Bay of Meil. At each site extensive sampling was undertaken to characterise the sites including particulate size analysis (PSA), sediment particulate organic carbon (POC), sediment sulphides (Quanterness and Bay of Meil only) and infaunal analyses (ITI and IQI). In addition, a novel design of sediment traps was deployed along four transects at each site during spring and neap tides to estimate the deposition of organic carbon whilst allowing resuspension of settled organic material. The estimated deposition rates were then compared with the site characteristics, IQI patterns and NewDEPOMOD model results. The main conclusions were that patterns and quantities of estimated carbon deposition were generally consistent with expectations and with the infaunal impacts (IQI), suggesting that the novel sediment traps can capture realistic patterns of organic waste deposition around fish farms. Modelling using the NewDEPOMOD default parameter settings led to nearly all simulated particles being moved out of the model domain, meaning that no benthic footprint could be captured. To generate a benthic footprint at these sites it was necessary to increase critical shear stress in the model to levels at which resuspension was almost completely turned off. However, particularly at times of spring tide this then led to waste deposition estimates which declined too rapidly with distance from the fish cages i.e., waste resuspension and re-dispersal was then being underestimated in the model. These results, taken with other published results on fish farm waste resuspension reviewed in part 1 of this report, suggest that NewDEPOMOD is not fully capturing the resuspension and redistribution processes occurring in the field. This behaviour most likely arises from the use of a spatially invariant critical shear stress in the model (although other issues cannot be ruled out). It seems likely that organic waste is more easily eroded from heavily enriched areas but becomes harder to resuspend when dispersed onto less enriched areas and that this behaviour is more significant over coarser sediments, including sands and gravels, compared to mud. Patterns in sediment sulphides also largely agreed with infaunal impact patterns although benthic samples with mid-range sulphide concentration (~200 – 1500 µM) showed a wide range of ecological states. Taken along with previously published results from Scotland and additional information from Canada, sulphide measurements do appear to be a rapid and reliable indicator of whether a sample is in ‘High’ IQI status but cannot discriminate between ‘Moderate’ and ‘Poor’ IQI status based on sulphide concentration alone. Samples with sulphides above 1500 µM are likely to have a ‘Bad’ IQI status, but this conclusion is based on a limited number of highly impacted samples. Recent analytical advances might alter this perception somewhat by giving more accurate sulphide measurements, although the overall patterns with biological community response are likely to remain. The main recommendations from the projects are:- a) Particle resuspension as encoded in NewDEPOMOD remains problematic. The present configuration requires ad hoc fixes to be applied to reduce levels of particle dispersion at higher energy sites. The most likely cause of the problems may be the use of a single value for bed shear-stress across the model domain. This leads to a recommendation that NewDEPOMOD code should be reviewed to evaluate the feasibility of allowing critical bed shear stress to be related to the degree of organic enrichment and sediment type. The modified model will then need to be re-evaluated to assess if this change improves its predictive capability in more dispersive environments. b) The use of sediment boxes placed flush with the seabed to directly measure net (considering resuspension) organic carbon deposition appeared successful. The technique could be applied at additional farm sites to generate more measurements across a wider range of site conditions for direct comparison with predictions from NewDEPOMOD (or other particle dispersal modelling tools). However, the technique does have limitations, especially regarding maximum deployment depth by divers. Furthermore, in any future studies, additional traditional design sediment traps (which do not allow resuspension) should also be deployed for comparison, and one or two reference sites included to confirm the background organic flux. c) Sulphide measurements may be useful to farm managers as a quick indication of stations which are likely to have less than ‘Moderate’ ecological status but is unlikely to provide a complete replacement for infaunal analyses as required by SEPA because it does not appear to allow discrimination between ‘Moderate’, ‘Poor’ and ‘Bad’ IQI status samples. e) Whilst measurement of sulphides on farm sites was demonstrated to be achievable using the ion-specific electrode (ISE) approach, the method is not without problems. Achieving accurate results requires careful maintenance and calibration of the probes and a recent study claims the method is less accurate than direct quantification of sulphides by UV-absorption, although ISE remains one of the standard fish farm benthic monitoring tools in Canada. We cannot therefore recommend the ISE approach at this time as an “easy, rapid, and reliable method for evaluating benthic community status” on Scottish fish farms in-line with SEPA requirements. f) Further field work at Scottish fish farms should explore the application of the recently published spectrophotometric methods described by Cranford et al. (Cranford et al., 2017, 2020 #11968). These methods may improve the accuracy of sulphide measurements compared with the ion-selective electrode (ISE) approach but would require additional equipment (UV-spectrophotometer) to be available at fish farm sites if analyses were to be performed on-site. Alternatively, samples may be preserved with zinc acetate and subsequently analysed using the methylene blue method, although this technique is not as sensitive as measuring UV-absorption on fresh samples. These approaches could potentially improve analytical precision and thus might improve discrimination between IQI status levels of benthic grab samples based on sulphide measurements. However, it must be cautioned that evidence to date suggests that biological responses to sediment sulphides appear to be quite variable and site specific, especially when sulphides levels are in the intermediate range (200 – 1500 µM). The method would thus require extensive further calibration against IQI for use within the Scottish regulatory framework. g) Further work on sulphides could be piggybacked on existing SEPA compliance monitoring to reduce costs but the equidistant sampling designs used are not ideal as they tend to lead to an unbalanced number of samples at each IQI state. Additional sampling for sulphides (and using sediment traps if deployed) would therefore probably be required to fully investigate the relationships between sulphide concentrations, IQI, sediment type and other site-specific factors. Log-distance sampling designs may be preferable to account for the usual exponential decline in organic waste deposition with distance from the cage edge. h) Incorporation of a diagenesis sulphide module into NewDEPOMOD would be achievable but would require a dedicated software development project. We suggest that it may be more useful to address recommendation (f) initially, because we cannot yet say how useful sulphide measurements around fish farms would be in the context of the Scottish regulatory framework.
... Macrofauna abundance has been found to differ between farm and reference sites 129,130 and change in response to farming activity 131 and fallowing. 76 The unimodal relationship between macrofauna abundance and enrichment stage, with increasing abundance of opportunistic taxa as enrichment stage increases until suddenly dropping off at high enrichment, has been observed during both the fallowing and reintroduction of farms. 88,89,124,125 In one instance, abundance fell dramatically at three months after reintroduction of a farm and remained low for the following year, 125 and in another, the typical peak after fallowing followed by decline was not observed due to the annual rather than monthly sampling regime used. ...
... Macrofauna abundance has generally been found to increase with distance from cage 68,76,126 increase with fallowing time, 76 and increase with exposure to farming over time. 130 The similar unimodal relationship to the one observed between abundance and enrichment state has also been observed between abundance and fallowing time with initial decrease during fallowing followed by an increase due to opportunistic taxa and then a gradual decrease. ...
... The number of macrofauna taxa in a sediment sample, typically determined by identifying fauna retained in a 0.4mm 91 or 0.5mm sieve 76,133 to the lowest possible level of identification. Number of taxa is also referred to as species richness. ...
Article
The ecosystem approach to aquaculture (EAA) is a strategy for the sustainable development of the aquaculture sector, but the question of how it can be practically implemented remains unclear. Indicators that can be applied at relevant scales of impact and that reflect the environmental status and change offer a means of operationalizing EAA. Therefore, a systematic literature review was carried out to identify environmental indicators referenced in salmon aquaculture literature and review their potential to support EAA. Using the PRISMA method for selecting journal papers, 101 articles that included 531 indicators were reviewed. Indicators were characterized based on the effect of aquaculture they measure, their similarity to other indicators extracted, and the scale at which they were applied. Indicators and their characteristics are presented in a searchable online database. A scoring method for evaluating indicators based on criteria drawn from environmental indicator literature and the potential scalability of indicators to meet the needs of EAA was developed and applied to the most frequently referenced indicators. Overall, near‐field indicators of benthic impacts dominated salmon aquaculture literature. Of the most frequently referenced indicators, those that scored highest based on criteria drawn from environmental indicator literature also scored highest on scalability and therefore their potential contribution to EAA. Overall, results suggest that additional research and application of far‐field environmental indicators in salmon aquaculture will be required to identify a suite of indicators that can be applied as part of EAA practice.
... According to Folke et al. (1994), this is equivalent to the nitrogenous waste produced by 9000 people and the phosphorous waste produced annually by 27,000 people in developing countries. Therefore, one of the main negative environmental effects caused by salmon farming is a change in the structure of marine sediments, impacting benthic communities (Pereira et al., 2004;Tomassetti and Porrello, 2005;Edgar et al., 2010). ...
... Our results also suggest that the percentage of organic carbon present in the sediment is not an accurate predictor of the temporal changes of the marine macro-benthic community. This supports previous findings from marine sediments close to salmon farms in Scotland (Pereira et al., 2004). In our study, we propose this could be due an elevated influx of organic matter associated with natural climatic conditions (prevalent elevated rainfall conditions). ...
... In the present study most impacted sites scored values around 2 for the Shannon's diversity index compared to values close to 4 found in control sites. Similar results were also found in Scotland where Shannon's diversity index was always lower than 3 in the salmon farming sites during the period of study (Pereira et al., 2004). Simpson's diversity, however, evidenced a very marked seasonal decrease in summer in both zones, but this decrease was considerably larger in the protected than in the exposed zone. ...
Article
The impacts of any activity on marine ecosystems will depend on the characteristics of the receptor medium and its resilience to external pressures. Salmon farming industry develops along a constant gradient of hydrodynamic conditions in the south of Chile. However, the influence of the hydrodynamic characteristics (weak or strong) on the impacts of intensive salmon farming is still poorly understood. This one year study evaluates the impacts of salmon farming on the marine sediments of both protected and exposed marine zones differing in their hydrodynamic characteristics. Six physico-chemical, five biological variables and seven indexes of marine sediments status were evaluated under the salmon farming cages and control sites. Our results identified a few key variables and indexes necessary to accurately evaluate the salmon farming impacts on both protected and exposed zones. Interestingly, the ranking of importance of the variables and the temporality of the observed changes, varied depending on the hydrodynamic characteristics. Biological variables (nematodes abundance) and environmental indexes (Simpson's dominance, Shannon's diversity and Pielou evenness) are the first to reflect detrimental impacts under the salmon farming cages. Then the physico-chemical variables such as redox, sulphurs and phosphorus in both zones also show detrimental impacts. Based on the present results we propose that the hydrodynamic regime is an important driver of the magnitude and temporality of the effects of salmon farming on marine sediments. The variables and indexes that best reflect the effects of salmon farming, in both protected and exposed zones, are also described.
... In Norway, salmon production is the most important aquaculture sector, accounting for more than 80% of the total aquaculture production (FAO, 2014). The on-growing phase of salmon takes place almost exclusively in open sea cages, releasing large amounts of organic matter into the surrounding environment in form of nutrients, faeces and waste feed (Pereira et al., 2004;Lee et al., 2006;Kutti et al., 2007;Huang et al., 2012). This organic enrichment can result in changes of the benthic sediment chemistry and macrofauna communities, primarily in the direct vicinity of the farms (Pereira et al., 2004;Obee, 2009;Boyra et al., 2004;Pohle et al., 2001), which has been studied on different spatial and temporal scales (e.g. ...
... The on-growing phase of salmon takes place almost exclusively in open sea cages, releasing large amounts of organic matter into the surrounding environment in form of nutrients, faeces and waste feed (Pereira et al., 2004;Lee et al., 2006;Kutti et al., 2007;Huang et al., 2012). This organic enrichment can result in changes of the benthic sediment chemistry and macrofauna communities, primarily in the direct vicinity of the farms (Pereira et al., 2004;Obee, 2009;Boyra et al., 2004;Pohle et al., 2001), which has been studied on different spatial and temporal scales (e.g. Karakassis et al., 1999;Kraufvelin et al., 2001;Lee et al., 2006;Brooks et al., 2003;Pohle et al., 2001). ...
... Measurements of physicochemical parameters of sediments, such as redox potential (Eh), pH and total organic carbon (TOC), are often applied as a main tool to monitor sediment degradation (Macleod et al., 2006;Black et al., 2008). However, macrofauna community structure is considered as one of the most powerful indicators of organic pollution (Carroll et al., 2003;Pereira et al., 2004;Lee et al., 2006). ...
... Beyond the impacts of organic off-load in water column and sediment, the ability of the environment to recover after cessation of aquaculture has been also studied. Rapid initiation recovery process has been mentioned, but far from complete even after a cessation period of several months La Rosa et al., 2001;Pereira et al., 2004) and also site dependable (Pereira et al., 2004;Sanz-Lázaro et al., 2011). ...
... Beyond the impacts of organic off-load in water column and sediment, the ability of the environment to recover after cessation of aquaculture has been also studied. Rapid initiation recovery process has been mentioned, but far from complete even after a cessation period of several months La Rosa et al., 2001;Pereira et al., 2004) and also site dependable (Pereira et al., 2004;Sanz-Lázaro et al., 2011). ...
... En 2006, en Escocia existían 475 granjas de maricultura e instalaciones en todos los fiordos principales ( fig. 1a). La operación de estas granjas ha causado inquietud sobre sus posibles efectos ambientales (Pearson y Black 2001), ya que se sabe que los desechos de las granjas de salmón impactan el bentos de los hábitats de fango de los fiordos (Cromey et al. 2002, Pereira et al. 2004. Existe una carencia de información sobre los efectos de granjas piscícolas en zonas de mareas fuertes. ...
... In 2006 there were 475 fish-farms in Scotland and no major fjords without mariculture installations ( fig. 1a). This has raised concerns over the environmental effects of such development (Pearson and Black 2001), since waste feed and faeces from salmon farms are known to impact the benthos of muddy fjord habitats (Cromey et al. 2002, Pereira et al. 2004). ...
Article
Scotland is the largest aquaculture producer in the European Union and utilizes almost all of its fjords for salmon culture. Recent UK policy has encouraged the movement of farm cages away from enclosed sites to areas with strong tidal flow because salmon farms are known to cause organic-enrichment of muddy substrata in areas with low tidal flow. This has resulted in a spate of applications to site cages over coralline algal gravel beds (termed maerl) that are usually strongly tidal and provide habitat for a diverse array of benthic Crustacea. In 2003 we studied the effects of farm waste on benthic crustaceans from a large salmon farm in Shetland that had been situated above a maerl bed since 1991. Annual monitoring reports showed a die-back of living maerl, periods of anoxia and an accumulation of organic material on the seabed within 25 m of the cages. Assessments of crustacean assemblages, quantified using 0.5-mm-sieved replicate (n = 5 per site) core samples, showed significant reductions in biodiversity near the farm. Some scavengers (e.g., the amphipod Socarnes erythrophthalmus) were far more abundant near the cages than at distances >75 m from the cages, but many small crustaceans (e.g., the tanaids Leptognathia breviremis, Typhlotanais microcheles and Psudoparatanais batei; the cumaceans Nannastacus unguiculatus, Cumella pygmaea and Vaunthompsonia cristata; and the amphipod Austrosyrrhoe fimbriatus) were impoverished near the cages. We found that benthic Crustacea were significantly impacted by the salmon farm, despite the presence of strong currents, probably due to the combined effects of organic wastes and the use of toxins to combat parasitic copepods. We recommend that "fallowing", whereby farm cages are moved between sites to allow benthic recovery, is not carried out at sites where long-lived biogenic habitats such as maerl occur because this will likely increase the area of habitat degradation.
... At finfish aquaculture sites, organic waste (e.g. faecal matter and unconsumed feed), if not adequately dispersed, can alter seafloor biogeochemistry and benthic community structure (Ye et al., 1991;Pereira et al., 2004;Shahidul Islam & Tanaka, 2004;Carvalho et al., 2006;Yokoyama et al., 2006;Kutti et al., 2007;Borja et al., 2009, Husa et al., 2013. Sedimentary infauna beneath aquaculture cages typically show a decreased biodiversity and a high abundance of opportunistic species compared with adjacent sites; consequently, ecosystem functioning in such sediments is affected (Ye et al., 1991;Crawford et al., 2001;Pereira et al., 2004;Carvalho et al., 2006;Kutti et al., 2008;Borja et al., 2009). ...
... faecal matter and unconsumed feed), if not adequately dispersed, can alter seafloor biogeochemistry and benthic community structure (Ye et al., 1991;Pereira et al., 2004;Shahidul Islam & Tanaka, 2004;Carvalho et al., 2006;Yokoyama et al., 2006;Kutti et al., 2007;Borja et al., 2009, Husa et al., 2013. Sedimentary infauna beneath aquaculture cages typically show a decreased biodiversity and a high abundance of opportunistic species compared with adjacent sites; consequently, ecosystem functioning in such sediments is affected (Ye et al., 1991;Crawford et al., 2001;Pereira et al., 2004;Carvalho et al., 2006;Kutti et al., 2008;Borja et al., 2009). In contrast, little is known on the impacts of aquaculture wastes on benthic community function at sites dominated by hard substrates. ...
Article
Full-text available
A new species of dorvilleid polychaete, Ophryotrocha cyclops, has been observed on the rocky seafloor underneath deep salmonid aquaculture sites on the south coast of Newfoundland, Canada. The distribution of these opportunistic worms is likely related to organic matter accumulation on the seafloor, and this species may have a role in remediation processes. To better understand the functional role of O. cyclops at aquaculture sites, it is important to know what they feed upon. Here, stable isotope analyses (δ13C, δ15N and δ34S) and trace element analyses were performed on dorvilleids and their potential food sources at three aquaculture sites. Stable isotope analyses revealed spatial and temporal variation in the isotopic carbon signature of O. cyclops, highlighting possible differences in the food sources of individual dorvilleids within and between sites. The isotopic composition of dorvilleids was closest to that of fish pellets; the presence of abundant lipid droplets in gut epithelial cells of O. cyclops suggests the assimilation of fish pellet-derived lipids. Trace element analysis indicated that O. cyclops does not concentrate the aquaculture tracers Zn or Cu to a large extent. However, concentrations of sulphur were high in O. cyclops compared with other sources. Taken together, results show that O. cyclops most likely consume both fish pellets and flocculent matter-associated bacteria. As such, they are involved in sulphur cycling and fish pellet degradation at aquaculture sites.
... Even at the 0 m sites, capitellid abundance was below 365 m -2 , which is well below typical abundances of 10s to 100s of thousands m -2 seen in areas with high levels of organic enrichment (e.g. Brooks et al. 2003, Pereira et al. 2004. Cirratulidae are also known indicators of organic enrichment (Glasby 2000), and their pattern of abundance at the north lease suggests organic enrichment, although that at the south lease does not. ...
... This compares to a mean of 1049 m -2 at the 1000 m sites in Fitzgerald Bay, lower than the abundances for individual taxa in many other studies (see previous paragraph). In organically enriched areas, there is typically a low richness, but high abundance, with a few opportunistic taxa dominating the assemblage (Pearson & Rosenberg 1978, Pereira et al. 2004). ...
Article
The culture of yellowtail kingfish Seriola lalandi in South Australia is one of the most rapidly growing aquaculture sectors in Australia. To date, there is a paucity of information on the environmental impacts of this industry, due to its relatively small size in comparison to other industry sectors. Here, we report on a study examining the response of a range of environmental variables to yellowtail kingfish aquaculture in Fitzgerald Bay, northern Spencer Gulf, South Australia. The clearest response occurred in several chemical variables, with an 81% increase in ammonia concentrations adjacent to cages relative to controls, increased sediment organic carbon (7 to 46%) and increased porewater phosphorus in the sediments (80 to 3077%). While there were also statistically significant effects on infaunal and epifaunal assemblages, results for both groups were equivocal because of high small-scale variability. For the infauna, assemblages at the sites furthest from cages tended to be similar to those adjacent to cages, while those at intermediate distances differed. No impacts were detected on phytoplankton, or on seagrasses (although the latter only occurred >250 m from any aquaculture cage). The lack of clear responses in the biotic datasets is probably related to the relatively low production levels (<2000 t yr1 at the time of the study), although the responses in the chemical variables provide a valuable early warning as production increases.
... A method of mitigation to reduce the long term negative impacts of this output and accumulation is fallowing (Macleod et al, 2004a). Fallowing is a process where aquaculture production is terminated for a set period of time in order to allow the benthic community underneath farms to recover (Pereira et al, 2003). Fallow times can range from weeks to months depending on the environmental conditions of the site (Macleod et al, 2004a). ...
... Assessments both of the chemical characteristics as benthic infaunal community of the site can be compared to reference sites (Macleod et al, 2004a;Pereira et al, 2003). If aquaculture sites have no reference indicators or sites to compare to AZTI's Marine Biotic Index (AMBI) can be used. ...
... 각 정점군에 대해 k-dominance curves (Lambshead et al., 1983) Table 1). (Rosenberg, 1976;Tapp et al., 1993;Borja et al., 2006;Munari et al., 2007) (Karakassis et al., 1999;Gray et al., 2002;Pereira et al., 2004). 예를 들어, 해상 가두리 양식에 의한 유기물 오염의 경우 사료 물질의 분해가 비교적 빠르며 오염의 영향권이 크지 않기 때 문에 상대적으로 오염으로부터 회복되는 과정이 빠르게 진행되지 만 생활하수와 같이 분해과정이 복잡하고 더딘 물질에 의한 오염 의 경우 그에 비해 회복이 느리게 진행되어 십 수 년까지도 걸리 는 것으로 알려져 있다 (Pereira et al., 2004;Smith and Shackley, 2006;Munari et al., 2003) Table 4. Combinations of environmental parameters giving the best matches between biological and environmental (dis)similarity matrices. ...
... (Rosenberg, 1976;Tapp et al., 1993;Borja et al., 2006;Munari et al., 2007) (Karakassis et al., 1999;Gray et al., 2002;Pereira et al., 2004). 예를 들어, 해상 가두리 양식에 의한 유기물 오염의 경우 사료 물질의 분해가 비교적 빠르며 오염의 영향권이 크지 않기 때 문에 상대적으로 오염으로부터 회복되는 과정이 빠르게 진행되지 만 생활하수와 같이 분해과정이 복잡하고 더딘 물질에 의한 오염 의 경우 그에 비해 회복이 느리게 진행되어 십 수 년까지도 걸리 는 것으로 알려져 있다 (Pereira et al., 2004;Smith and Shackley, 2006;Munari et al., 2003) Table 4. Combinations of environmental parameters giving the best matches between biological and environmental (dis)similarity matrices. k means the size of the subset of the envrionmental parameters for each combination. ...
Article
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This study was performed to investigate changes in benthic environment and macrobenthic polychaete communities in Gamak Bay where various environmental quality improvement projects have been implemented in recent years. Field surveys were carried out in February, 2005 and February, 2006 and twenty stations were selected to explore whether or not there were between-year differences in biotic and abiotic variables. Of 10 environmental variables measured, only three variables including dissolved oxygen (DO), total ignition loss (IL), acid volatile sulfide (AVS) showed significant between-year differences. Specifically, IL and AVS were, on average, 1.5 and 3 times lower in 2006 compared to those in 2005, respectively, which was more pronounced in the northern part of the bay. A total of 95 polychaete species was sampled from the two sampling occasions. Between-year differences in the number of species, abundance, and diversity were varied from place to place. In the northern part of the bay, fewer species were found in 2006 rather than in 2005, but diversity increased in 2006 due to the reduction in dominance of a few species. On the contrary, in the central part of the bay, the number of species, abundance and diversity prominently increased in 2006. In the southern part of the bay, all the biological indices maintained similarly during the two years. Dominant species in 2005 were such opportunistic or organic pollution indicator species as Lumbrineris longifolia, Capitella capitata, Mediomastus californiensis, Pseudopolydora paucibranchiata, etc. and most of them were mainly distributed in the northern part of the bay and in the proximity of it. In 2006, however, Euchone alicaudata, L. longifolia, Paraprionospio pinnata, Flabelligeridae sp., etc. were dominant and distributed mainly in the central part of the bay. Multivariate analyses showed that the whole polychaete community could be divided into 5 groups reflecting the geographical positions of the sampling stations and temporal variation particularly in the northern part of the bay. According to the results of BIO-ENV procedure, TOC () and AVS () as a single variable best explained the polychaete community structure. The best combination was made by such variables as TOC, AVS, sorting coefficient, and water temperature (). In conclusion, between-year differences in biotic and abiotic variables imply that recent efforts for the environmental improvement produced positive influences on the benthic environment of Gamak Bay, particularly the northern part of the bay.
... Farm waste footprints may be hotspots of GHG production, but the magnitude of that production is still largely undescribed. If climate change reduces the frequency of DWR, the processing of farm-derived OM may be less efficient as less oxygen will be available to fuel aerobic respiration (Brooks et al., 2000;Hartstein, 2003;Pereira et al., 2004). This may lead to possible increased GHG production and will facilitate the spread of Beggiatoa matting (Crawford et al., 2001;Crawford, 2003). ...
Article
Deep coastal inlets are sites of high sedimentation and organic carbon deposition that account for 11 % of the world's organic carbon burial. Australasia's mid- to high-latitude regions have many such systems. It is important to understand the role of climate forcings in influencing hypoxia and organic matter cycling in these systems, but many such systems, especially in Australasia, remain poorly described. We analysed a decade of in situ water quality data from Macquarie Harbour, Tasmania, a deep coastal inlet with more than 180 000 t of organic carbon loading per annum. Monthly dissolved oxygen, total Kjeldahl nitrogen, dissolved organic carbon, and dissolved inorganic nitrogen concentrations were significantly affected by rainfall patterns. Increased rainfall was correlated to higher organic carbon and nitrogen loading, lower oxygen concentrations in deep basins, and greater oxygen concentrations in surface waters. Most notably, the Southern Annular Mode (SAM) significantly influenced oxygen distribution in the system. High river flow (associated with low SAM index values) impedes deep water renewal as the primary mechanism driving basin water hypoxia. Climate forecasting predicts increased winter rainfall and decreased summer rainfall, which may further exacerbate hypoxia in this system. Currently, Macquarie Harbour's basins experience frequent (up to 36 % of the time) and prolonged (up to 2 years) oxygen-poor conditions that may promote greenhouse gas (CH4, N2O) production altering the processing of organic matter entering the system. The increased winter rainfall predicted for the area will likely promote the increased spread and duration of hypoxia in the basins. Further understanding of these systems and how they respond to climate change will improve our estimates of future organic matter cycling (burial vs. export).
... In contrast, O. hartmanni (r), the least heat tolerant species, is characterised by very low densities in subtidal waters (1-7 indiv.; Online Resources 2, Table S1) but is among the most abundant macrobenthic species in the sediments of fish farms on the North Atlantic coasts (Pereira et al. 2004), suggesting its preference for colder waters. Similarly, O. puerilis (u) is among the most physiologically sensitive species to elevated temperatures and it capitalizes on thermal habitats that better match its preference for colder temperatures. ...
Article
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Among ectotherms, rare species are expected to have a narrower thermal niche breadth and reduced acclimation capacity and thus be more vulnerable to global warming than their common relatives. To assess these hypotheses, we experimentally quantified the thermal sensitivity of seven common, uncommon, and rare species of temperate marine annelids of the genus Ophryotrocha to assess their vulnerability to ocean warming. We measured the upper and lower limits of physiological thermal tolerance, survival, and reproductive performance of each species along a temperature gradient (18, 24, and 30 °C). We then combined this information to produce curves of each species’ fundamental thermal niche by including trait plasticity. Each thermal curve was then expressed as a habitat suitability index (HSI) and projected for the Mediterranean Sea and temperate Atlantic Ocean under a present day (1970–2000), mid- (2050–2059) and late- (2090–2099) 21st Century scenario for two climate change scenarios (RCP2.6 and RCP8.5). Rare and uncommon species showed a reduced upper thermal tolerance compared to common species, and the niche breadth and acclimation capacity were comparable among groups. The simulations predicted an overall increase in the HSI for all species and identified potential hotspots of HSI decline for uncommon and rare species along the warm boundaries of their potential distribution, though they failed to project the higher sensitivity of these species into a greater vulnerability to ocean warming. In the discussion, we provide some caveats on the implications of our results for conservation efforts.
... Electrons are essential to all inorganic and organic chemical reactions. Redox potential measurements allow rapid characterisation of the degree of reduction and predict various compound stability that regulates nutrients and metal availability in soil and sediment (Eggleton and Thomas, 2004;Pereira et al., 2004). Wong and Yang (1997) found that high redox potential and low pH are associated with chemical equilibrium disruption and the release of heavy metals from marine sediments. ...
Article
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Marine aquaculture sites at Kukup Strait in the peninsula of Malaysia are experiencing a decline in water quality in the last five years, resulting in high mortality rates (50 - 80%), seasonal massive fish mortalities and poor profitability. Currently, Kukup farmers are involved in intensive aquaculture within the existing aquaculture zone. This study explores the sustainability of a modern mariculture method, where fish farms are relocated to deeper waters with higher flushing rates, and high-density polyethylene (HDPE) are used to improve water quality. Several site selection criteria are utilised in identifying the proposed aquaculture industrial zone: 1) bathymetry depth (operational requirement: 10 m to 30 m), 2) located within the Kukup Port Limit, 3) does not interfere with the Kukup ferry navigation route, and 4) distance from Kukup mainland. Site feasibility analysis, including hydrodynamics, meteorology, water quality, sediment quality and macrobenthos assessment, was conducted to compare the proposed and existing aquaculture sites. It was found that the water quality at the existing site contained higher concentrations of fecal coliform and nutrients and salinity fluctuations. Tropical finfish can survive under these conditions with poorer fish health and higher fish mortality. Apart from that, the flushing capacity is higher in the proposed site, indicating the capacity to handle moderate-intensity aquaculture. Moderate-intensity aquaculture using HDPE cages could be profitable for the local fish farmers. Therefore, it is suggested that other locations within Kukup Straits with deeper waters (> 25 m) with possibly improved water quality and the ability for intensive aquaculture production should be explored for a larger depth and economics of scale.
... In this study, the redox values at 900 m were close to − 200 mV and AVS was around 10 mg kg − 1 . In reference zones for coastal and off-coast fish farming, redox levels generally range from − 50 to +200 mV (Brooks and Mahnken, 2003;Karakassis et al., 1998;Macleod et al., 2006;Matijević et al., 2012;Pereira et al., 2004;Sanz-Lazaro and Marin, 2006;Wilding, 2012), while AVS values are up to two orders of magnitude lower than those reported in this study (Aguado-Giménez et al., 2007;Brooks and Mahnken, 2003;Tsutsumi, 1995;Vita and Marin, 2007). ...
Article
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Marine aquaculture is expanding offshore, where the environmental interactions are not yet fully understood. We performed a benthic environmental assessment of an offshore fish farm on unconsolidated sediment. The physicochemical variables showed marked changes just under the fish farm, although the structure of the community and its bioturbation potential were not influenced. Under no or minimum influence from the fish farm, the physicochemical variables, including acid-volatile sulphides and redox, were notably different to those found in unaffected coastal areas. For this reason, classifications of the environmental status based on physicochemical variables should be adapted to offshore areas. Despite the low degree of impact detected, the organic matter carrying capacity should be carefully determined to avoid environmental drawbacks in terms of fine-grained offshore sediments. Offshore aquaculture could have a lower environmental impact than other types of aquaculture located closer to the coast, but further research is needed to obtain conclusive results.
... Olika arter av bottenfauna är också relativt långlivade, stationära och påverkas av förhållandena i både sedimentet och vattenmassan, vilket gör bottenfaunan till en bra indikator på långtidsförändringar i vattenmiljön (PERUS & BONSDORFF 2004). Trots att bottenfaunan är känslig för näringsbelastning är det viktigt att även studera vatten-och sedimentparametrar eftersom de mest känsliga arterna inte förekommer förrän den omgivande miljön har återhämtat sig (PEREIRA et al. 2004). ...
Technical Report
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Beräkning av ekologisk status för Ålands ytvattenförekomster utgående från kartering av makrofyter: ett förslag till övervakningsprogram och harmonisering av metoder mellan Åland och Finland (Assessment of ecological status for the surface waters of Åland based on macrophyte surveys: a proposal for an environmental monitoring program and for harmonization of methods between Åland and Finland)
... Olika arter av bottenfauna är också relativt långlivade, stationära och påverkas av förhållandena i både sedimentet och vattenmassan, vilket gör bottenfaunan till en bra indikator på långtidsförändringar i vattenmiljön (PERUS & BONSDORFF 2004). Trots att bottenfaunan är känslig för näringsbelastning är det viktigt att även studera vatten-och sedimentparametrar eftersom de mest känsliga arterna inte förekommer förrän den omgivande miljön har återhämtat sig (PEREIRA et al. 2004). ...
Technical Report
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Återhämtning av vattenmiljön efter avvecklandet av fiskodling: uppföljning av återhämtningsstatus vid Andersö och Järsö samt vid en ny lokal, Bergö (Recovery of the aquatic environment after the cessation of fish farming: a follow up study of the recovery status at Andersö and Järsö and at a new site, Bergö)
... Fig. 6), indicating sedimentation of fish-farm effluent in this area. The effect of aquaculture waste on the benthic community can reach a distance of hundreds of metres (Weston, 1990); therefore in future studies, benthic fauna should be included because they are more sensitive impact descriptors than the chemical properties of the sediment (Carrol et al., 2003;Pereira et al., 2004). ...
Article
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While aquaculture is growing rapidly all over the world and generating many economic benefits, so have the environmental concerns about the externalities posed by the fish-farming industry. The distribution profiles of organic compounds and inorganic elements were explored in marine surface sediments collected in proximity of two active Norwegian fish farms, Hestøya and Nørholmen (<200–1100 m from the perimeter edge of the installations). Overall, the sediment organic matter (SOM) content was 7.3 ± 4.9%, with 7.9 ± 5.1% and 4.0 ± 0.5% for Hestøya and Nørholmen, respectively. A non-targeted analysis was performed for screening organic compounds in marine sediments, and the presence of 60 compounds was detected. Among suspect compounds were alkanes, alkenes, aromatics, aldehydes, ketones, esters, alcohols, diols, polycyclic aromatic hydrocarbons (PAHs), terpenes and terpenoids. Heptanal, benzaldehyde, 4-oxoisophorone, 1,7-dimethylnaphthalene and 3-bromophenol were the most abundant compounds in marine sediments. In total, concentrations of 47 elements were measured, concentrations of As, Cd, Cr, Cu, Hg, Mo, Ni, Sn and Zn were strongly influenced by anthropogenic inputs, while concentrations of Ce, Co, Al, Fe and Ti were related to the geology of the local bedrock. The chemical composition of marine sediments was different at Hestøya and Nørholmen, indicating different anthropogenic inputs in these areas. In general, concentrations of toxic elements were below the proposed guidelines for Norwegian marine sediment quality and can be characterised as background pollution. Overall, fish-farming activities had only a minor or negligible influence on marine sediments and are unlikely to cause any harm to local aquatic life in the studied area.
... Based on the correlation analysis, factors that were most significantly impacted by the cage aquaculture are Secchi depth and nutrients concentrations (NO3-N, TN, COD), while pH and dissolved oxygen concertation were not affected. During that period a large amount of uneaten feed remains in the water column (WESTON et al., 1996;BUREAU & CHO, 1999), which affects the water transparency and nutrient content in close vicinity of the farms (PEREIRA et al., 2004;GORLACH-LIRA et al., 2012). The uneaten feed and fish feces are a major source of phosphorus and nitrogen load in the intensive aquaculture, which explains the positive correlation between the parameters (PODEMSKI & BLANCHFIELD, 2006). ...
Article
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The present study analyzed the interactions between the environmental parameters, microbiological water quality indicators, and phytoplankton in Kardzhali reservoir, which is one of the largest and economically significant water bodies in Bulgaria, with highly developed cage-aquaculture. Data sets of eighteen parameters from 5 monitoring sites during 2016-2018 were used for analysis. We have applied multivariate methods, aiming to identify the key parameters affecting the communities, including the impact of the net-cage farms. The ANOSIM (analysis of similarities), showed significant differences in the values of physicochemical factors between the control site and the area for aquaculture, with higher nitrate, total nitrogen, and COD (chemical oxygen demand) content near the net-cages. The results were confirmed by the high R-value (R=0.87; p<0.01). The conducted PCA (principal component analysis) showed that only three principal components (PCs) are need to group the physicochemical parameters, explaining 90.5% of the total data variation. PC1 was formed by nitrogen forms and COD, PC2 represents the physical source of the variability (pH and dissolved oxygen) and PC3 was loaded with total phosphorus (0.537) and ammonium nitrogen (0.764) concertation. The parameters with the highest impact on the abundance of heterotrophic bacteria (TVC) include temperature, TN, and COD, while the phytoplankton community was negatively correlated with Secchi depth and COD. The redundancy analysis confirmed that the location of the sampling station significantly affects the studied variables and that net-cage aquaculture is a major anthropogenic factor in Kardzhali reservoir.
... Some studies had shown that after the cessation of fish production or after fallowing (i.e. period during which there is a pause in production), the opportunistic taxa undergo a decline in only two months (Zhulay et al., 2015), or six months , whereas the impact could have a duration of several years (Brooks et al., 2004;Pereira et al., 2004;Keeley et al., 2012aKeeley et al., , 2012bKeeley et al., , 2015. In the case of the cessation of activity in the RdC salmon farm, it will be interesting to survey the resilience of benthic habitats in this area. ...
Article
The Rade de Cherbourg (RdC), in the North Cotentin (Normandy, English Channel) is the only French coastal zone where an offshore salmon farm has been in operation over the past three decades. Our study leads to the identification of the Ecological Quality status of benthic habitats based on a one-year survey (2013–2014) underneath and near the cages as well as in non-impacted areas lying outside the influence of salmon farming. The semi-diurnal high tide regime of the Rade de Cherbourg (5 to 8 m tidal range from neap to spring tide) should prevent any significant accumulation of Organic Matter (OM) under the cages. Nevertheless, higher Total Organic Carbon (TOC) and the presence of opportunistic species at sampling stations under and near the cages indicate an impact of salmon farming on the benthic habitats. Three benthic assemblages are identified, corresponding to three sediment types with different levels of OM enrichment. The presence of several indicator species, such as the polychaete worm Capitella minima belonging to the Capitellidae, reflects the local impact of fish farming without long-term accumulation of OM in the shallow waters of the RdC. Moreover, one of the main characteristics of the macrofauna of the RdC and neighbouring zones is the current very high abundance and dominance of the tanaid Apseudopsis latreillii in diverse sediment types. Benthic indices (AMBI, M-AMBI, and BO2A) were also able to distinguish three main zones in relation to the distance to salmon cages.
... Muslow et al. [24] explained how soft-bottom ecological assemblages have been collapsing in two fiords of Chilean Patagonia from industrial aquaculture through contamination including nitrates, phosphates and ammonia, resulting in reduced oxygen conditions and a dark crust on the seabed. This supports a wide-ranging literature from other parts of the world that organic waste from industrial aquaculture creates impact on benthic sediments seeing biodiversity decrease and physio-chemical properties change [25][26][27]110]. In eutrophic conditions authors such [28] describe the spread of a white crust of Beggiatoa bacteria on this black anoxic crust, and on gorgonian species in the Comau fiord (Hausmann et al., 2013). ...
... Studies have been conducted on the recovery rate of infauna macrobenthic invertebrates after the cessation of human disturbances in several regions of the world, for example British Columbia (Brooks et al. 2003), Scotland (Pereira et al. 2004), and the Gulf of Mexico (Washburn et al. 2016). In Greece, Karakassis et al. (1999) showed that the total benthic recovery had not been achieved 23 months after the contaminating event. ...
Article
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Coastal oil spills constitute significant threat to biotic energy distribution, and biodiversity integrity amongst others. This study monitored the recovery of low-intertidal, soft-bottom infauna macrobenthic invertebrates in Bodo Creek intermittently over a 7-year period post oil spill. Samples were taken twice a month (spring and neap low tides) for 6 months (September 2015–February 2016) at sites previously studied (pre-spill baseline studies, 3-year and 5-year post-spill studies) for the effects of oil pollution using the same sampling methods used during initial studies of the same area. Comparatively, the initial studies reported Polychaeta as the dominant class against the dominant Crustacea reported in this 7-year post-spill study, indicating a change in the community structure of the study area. Infauna macro-invertebrate communities recorded showed an improvement (that is, increased species richness and number of individuals) over the initial 3-year and 5-year post-spill studies. However, relating the results to the initial baseline pre-spill studies, an annual average of 9.7% recovery rate was observed. Analysis of results showed that the total hydrocarbon content (THC) of the sediment remained high (90.08–12,184 mg/kg) but was markedly lower than levels observed during the initial post-spill study (6422–7186 mg/kg). Tidal flushing and biodegradation processes were deemed responsible for the reduction in THC. This study provides a rare dataset that describes the effects of oil pollution on a previously near-pristine estuarine environment in the tropics.
... It can be inferred that the pollution sources flowing in via rivers directly affect the formation of hypoxic water masses in the northern inner bay. Environmental restoration is greatly affected by the nature of the substances polluting the environment (Gray et al., 2002;Pereira et al., 2004). In the case of organic pollution, the environment recovers relatively slowly from substances with slow, complex decomposition processes, such as sewage, in comparison to the recovery from pollution caused by feed and primary production (Munari, 2003;Smith and Shackley, 2006). ...
Article
This study investigated sediment oxygen consumption rates and geochemical characteristics using chamber experiments and geochemical analyses in the hypoxic area of Gamak Bay, Korea. The organic carbon contents of surface sediments in Gamak Bay were higher in the northern inner bay area, and dropped off toward the southern outer bay. The vertical profiles of calcium carbonate content in piston core sediments indicated that hypoxia has frequently occurred during the past century in the northern inner bay. Sediment chamber experiments were conducted in February, May, August, and November 2010 and 2011 in the hypoxic area of the bay. In the sediment incubation experiments at site C3 in the northern inner bay and site C17 in the southern outer bay, the sediment oxygen consumption rate ranged from 3.98-12.43 mmol m ⁻² d-1 and 3.28-8.18 mmol m ⁻² d ⁻¹ , respectively. When the oxygen was completely depleted, hydrogen sulfide was released at 1.38 and 1.3 mmol m ⁻² d ⁻¹ at sites C3 and C17, respectively.
... Sulphide-oxidizing bacteria have been considered a primary indicator of benthic organic enrichment, hypersulphidic or methanogenic substrates associated with (1) natural settings consisting of oxygen-minimum-zone sediments (Levin, 2003), deep organic-rich arctic fjords (Jørgensen et al., 2010), organicrich lagoons (Jørgensen and Revsbech, 1983), hydrothermal vents (MacGregor et al., 2013;McKay, 2011), cold hydrocarbon seeps (Vigneron et al., 2013), seafloor mud volcanoes (Milkov et al., 1999), whale-carcass deposit (Smith et al., 1989); (2) aquaculture activities within deep fjords (Bungay, 2012;Hall-Spencer et al., 2006;Hamoutene et al., 2015;Krost et al., 1994;Mersereau, 2015;Pereira et al., 2004;Sutherland, Sterling, and Ou, 2018), gulfs and bays (Angel, Krost, and Silvert, 1998;Simone, 2014;Weston, 1990), and sublittoral maerl beds (Hall-Spencer et al., 2006); and (3) other anthropogenic inputs made up of wood waste (Elliott, Spear, and Wyllie-Echeverria, 2006) and sewage outflows (Kim et al., 2007). Although sulphide-oxidizing bacteria are restricted to steep anoxic-oxic gradients across substrate interfaces (Jørgensen, 1982), they appear to be flexible in their preference of substrate types that couple to support strong oxygen-sulphide chemoclines (Jørgensen and Revsbech, 1983;Kamp, Roy, and Schulz-Vogt, 2008;Nelson, Jørgensen, and Revsbech, 1986;Preisler et al., 2007;Rosenberg and Diaz, 1993;Teske and Nelsen, 2006). ...
Article
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Sutherland, T.F.; Sterling, A.M.; Shaw, K.L.; Blasco, N.N.J., and Bradford, M.J., 2019. Detecting indicator taxa associated with benthic organic enrichment using different video camera orientations. Journal of Coastal Research, 35(2), 467–479. Coconut Creek (Florida), ISSN 0749-0208. Two video cameras mounted on a remotely operated vehicle (ROV) were used to generate paired forward-facing (FF) and downward-facing (DF) observations of benthic epifauna along 10 single transects at eight marine finfish aquaculture sites in British Columbia, Canada. The abundance of mat-forming primary indicators of organic enrichment, such as sulphide-oxidizing bacteria and opportunistic polychaete complexes (OPC), were quantified through percentage coverage estimates. Coverage estimates for sulphide-oxidizing bacteria were strongly correlated between the FF and DF orientations across all substrate types. The occurrence of OPC was limited to a single mixed-substrate site, which provided the strongest FF vs. DF relationship within this study. In contrast to sulphide-oxidizing bacteria, epifaunal abundance (count data) revealed strong relationships between camera orientations for fine sediments and mixed sediments and a weaker relationship observed for vertical rock wall environments. Similar observations occurred for estimates of both sessile (dominated by plumose anemones) and motile taxa guilds comprising the total epifaunal community. Weaker relationships associated with the rock wall substrate are likely due to alternating blackout periods experienced by each camera orientation as the ROV passes vertical or ledge habitat zones. Overall, a combination of FF and DF video orientations may provide more robust abundance estimates for settings that are characterized by various substrate grades and structural and/or mat-forming taxa.
... Organic matter in surface sediment is an important source of food for benthic fauna (Tomassetti et al. 2016). However, an overabundance of OM may lead to reduction in species richness, abundance and biomass, and the remediation of enriched sediments may take several years (Pereira et al. 2004). The TP concentrations recorded in the present study were relatively high in the sediment (Karakassis et al. 1998, Porrello et al. 2005. ...
Article
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This study investigated the environmental impact of offshore floating sea cages and the influence of runoff on cage fish farming in SE Gulf of California via the analysis of the physico-chemical profiles of the water column and sediments, located in SE Gulf of California, Mexico. Water and sediment samples were analyzed for physico-chemical parameters. In general, nitrates showed the highest concentrations of nutrients in the potential impact station (1.92 mg L-1). The results displayed temporal variations in the NH4, NO3, and PO4 in the water column as well as variations in the clay and organic matter in the sediment. The observed trends of these parameters were toward higher concentration in the potential impact and control stations
... Nickell et al. (1995) and Nickell et al. (1998) studied the recovery process at three Scottish sites and found that roughly normal biological community structure was restored over 2 years. Pereira et al. (2004) took samples from Loch Creran over 15 months of fallowing. They reported that the macrobenthic community "at the two stations furthest from the fish cage site showed signs of recovery with time" but were "still moderately to slightly disturbed at the end of this study". ...
Technical Report
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The ECCLR Committee is carrying out this work in advance of the Rural Economy and Connectivity (REC) Committee’s forthcoming inquiry on aquaculture in Scotland, the terms of reference for which will be considered in the coming weeks. The ECCLR Committee’s focus is the report commissioned by SPICe and undertaken by SAMS Research Services Ltd (SRSL). This report contains a review of literature on the environmental impacts of salmon farming in Scotland, the scale of the impacts and approaches to mitigating the impacts. This provides an update of the Scottish Government commissioned report: Review and synthesis of the environmental impacts of aquaculture, published in 2002.
... The ability to accelerate seabed recovery also has broader social and environmental implications, as it may provide a means to shorten the pathway to full recovery after farming has ceased. While the benthic effects from organic enrichment have been shown to recover substantially within 1-2 years (Keeley et al., 2015;Macleod et al., 2008;Villnas et al., 2011), reverting to a natural functional state can take much longer (Brooks et al., 2004;Keeley et al., 2014;Pereira et al., 2004). There are also other farm-derived contaminants associated with the sediments that may have even longer recovery profiles. ...
... Wu (1995) found that 1% to 15% of the feed was uneaten when using artificial feed, but this value increased to 40% when fresh feed (trash fish) was used. Organic matter enrichment beneath sea cages together with the absence of oxygen stimulate the proliferation of anaerobic sulfate-reducing bacteria that produce sulfides (Holmer and Kristensen, 1992;Heijs et al., 2000;Kristensen, 2000), which in turn may cause a decline of the macrofaunal benthic communities in the area (Pereira et al., 2004;Sanz-Lázaro and Marin, 2006). On the other hand, to a certain extent in nutrient poor areas, sedimentation can stimulate infauna production (Vizzini and Mazzola, 2004;Vizzini et al., 2005;Lin and Fong, 2008;Kutti et al., 2008) and bioturbation activity can accelerate the recovery of the environment (Karakassis et al., 2000;Kris-tensen, 2001;Michaud et al., 2006). ...
Article
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The present study investigated the applicability of integrated polychaete-fish culture for fish waste removal to offset negative impact induced by organic benthic enrichment. A field study demonstrated that deposition rate was significantly higher underneath the fish farm than that in control area. The material settling under the farm was characterized by a high amount of fish feces (45%) and uneaten feed (27%). Both feeding rate (FR) and apparent digestibility rate (ADR) increased with decreasing body weight, as was indicated by significantly a higher rate observed for the groups containing smaller individuals in a lab study. The nutrient in fresh deposited material (De) was higher than that in sediments collected under the farm (Se), resulting in lower feces production but higher apparent digestibility rate for the De group as feeding rate was similar. Consequently, higher nutrient removal efficiency was observed in the De group. A mass balance approach indicated that approximately 400–500 individuals m−2 is required for removing all waste materials deposited underneath the fish farm, whereas abundance can be lower (about 300–350 individuals m−2) when only the fish waste needs to be removed. The results showed that a significant amount of waste had been accumulated in the fish cages in Sanggou Bay. The integration of fish with P. aibuhitensis seems promising for preventing organic pollution in the sediment and therefore is an effective strategy for mitigating negative effect of fish farms. Thus such integration can become a new IMTA (integrated multi-trophic aquaculture) model in Sanggou Bay.
... This demonstrates that the assemblage structures at all sites would recover to a similar status following harvesting for a few months. Studies on the effects of aquaculture fallowing the recovery of macrofaunal communities showed that several years (over 0.5-5 years) are required to complete the succession, while at most bivalve farming sites, the effects on macrofaunal communities after removal/disassembly of the farming equipment were none or less negative (Martin et al., 1991;Karakassis et al., 1999;Pereira et al., 2004;Costa and Nalesso, 2006;Mallet et al., 2006;Keeley et al., 2014). This occurred because no artificial feed is needed for bivalve farming, in contrast to fish farming. ...
... Stenton-Dozey et al. 1999). Similarily, studies overseas that examined the effects on the benthos of fish farms have often indicated a restricted spatial impact (e.g. 25 m from farm cages, Karakassis et al. 2000), from which communities can take more than a year to recover after farm production ceases (Pereira et al. 2004). ...
Technical Report
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Soft sediments are unconsolidated substrata such as mud, sand and gravels that form extensive areas of habitat in the coastal and offshore areas of the New Zealand marine environment. Diverse biotic assemblages are associated with these habitats that are integral to the functioning of the soft sediment ecosystem. Some of these assemblages are currently threatened by anthropogenic activities. The availability of sufficient and suitable data frequently restricts the spatial extent over which patterns of diversity and threats can be assessed, and as a consequence, the suggestions made concerning the need for further research that will allow for a better understanding of biodiversity and management of the environment. To facilitate the best utilisation, and collection, of past and new biodiversity data it is wise to undertake a thorough and documented review of information already available. Such a review will provide a useful synthesis of current knowledge and can include the identification of particular issues of interest or concern. The objectives of the present project were to review existing published and unpublished sources of information on soft-sediment marine assemblages around New Zealand; to thereby identify hotspots of biodiversity, areas of particular vulnerability, and gaps in knowledge and make recommendations on areas or assemblages that could be the subject of directed research in future years. A database: The Marine Soft Sediment Biodiversity Bibliographic Database, was constructed to house over 700 references for reports, journal papers, theses, video material, conference proceedings and databases. The vast majority (95%) of the references are post-1960 and the subject of these articles spatially concentrated. These findings probably reflect the distribution of on-going land and coastal development and population growth; mussel farms; science researchers and institutes (via their proximity to study sites). Areas where there were relatively few records probably reflect the distance of these locations from human population centres; their inaccessibility; and their relative lack of soft-sediment habitats. The written review was conducted separately for seagrass and mangroves, macroalgae, intertidal, and subtidal macroinvertebrate assemblages. These extensive and comprehensive reviews addressed the project’s objectives and thereby addressed some of the objectives of New Zealand’s Biodiversity Strategy. The reviews include a series of recommendations that indicate the types of research that is considered necessary in order to address perceived shortfalls in knowledge of biodiversity, its importance to ecosystem function, and the threats and consequences of disturbance by anthropogenic activities. More studies are recommended than can be presently supported by the biodiversity research funds that the Ministry of Fisheries administers. It is proposed that there now follow a formal and rigorous procedure to prioritise the recommendations, in order that important and scarce national biodiversity funds are directed towards a research agenda that will best deliver on New Zealand’s commitment to the Convention on Biological Diversity.
... The wastes from fish cage farming reduce dissolved oxygen in the water and lead to high levels of acidvolatile sulphides (AVS) in the sediment, which causes a decline in macrofaunal benthic communities in the area (He et al. 1997;Pereira et al. 2004;Wei et al. 2005;Sanz-Lázaro & Marin 2006). Organic loads have a distinct impact on meiofaunal densities, which have been observed to be 50% lower under fish cages than at control sites (Mazzola et al. 2000). ...
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The effects of three temperatures (15°C, 20°C and 25°C) and four feed types (artificial feed, AF; sediment, SM; fish faeces, FF; and fish meat, FM) on the growth, carbon budget and nitrogen budget of the polychaete Perinereis aibuhitensis were evaluated over a 35 day period. The final body weight and specific growth rate (SGR) of P. aibuhitensis were significantly affected by temperature and feed types (T, F = 15.831, P = 0.000; Feed, F = 81.827, P = 0.000), but the interaction between these factors was not significant (F = 0.435, P = 0.848). The worms achieved the highest SGR in the AF group at 20°C. However, the SGR in the SM group was only half that of the other groups. The food conversion efficiency (FCE) was significantly lower at 25°C than at 15°C and 20°C (P < 0.05). The FCE was highest in the FM group (P = 0.000), with a mean of 39.83%. The apparent digestibility rate (ADR) at 25°C was significantly higher than at 15°C and 20°C (P < 0.05). These findings suggest that the higher FCE coupled with ADR (78.48%) resulted in higher SGR in worms that were fed artificial feed at 20°C. The slow growth in the SM group was attributed to the lower organic content in sediment and the higher expenditure of carbon and nitrogen in faeces and metabolism. The proportion of total C and N deposited was lower in groups fed with the higher-quality feed used for fish cage farming. Most of feed carbon and nitrogen were released into the water by polychaetes, which was good for the sediment environment recovery under the fish cages.
... Pearson y Rosenberg (1978) afirman que los residuos vertidos desde las piscifactorías afectan a la distribución de la fauna bentónica, con presencia de Beggiatoa en zonas muy contaminadas y especies oportunistas como el poliqueto C. capitata en zonas contaminadas. La comunidad de macrofauna bentónica, según numerosos estudios, es mejor indicador de impacto que las propiedades químicas del sedimento (Carrol et al., 2003;Pereira et al., 2004). ...
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The Environmental Monitoring Programme for four fish farms located in the western Mediterranean Sea was studied in order to assess their suitability for detecting possible environmental impact in the surrounding marine ecosystems. A significant number of physical, chemical, and biological parameters, both in water and sediments, were reviewed, as well as their monitoring frequency. These results lead to the conclusion that water quality should not be considered a strong indicator of caged fish farms impact; it is much more appropriate to use other parameters related to sediments, partirularly those indicating the health of benthos ecosystems. An Environmental Monitoring Programme for cage fish farms is proposed.
... Coastal aquaculture perturbations are mainly derived from surplus fish feed and waste products accumulated on marine sediment (Gowen and Bradbury, 1987;Kalantzi and Karakassis, 2006) which cause silting, increased oxygen demand, anoxic sediment generation and toxic gases on the seabed (Wu, 1995;Borja, 2002). These negative effects may defaunate and disturb patches in soft-bottom communities (Berge, 1990;Lu and Wu, 1998;Pereira et al., 2004). Indeed, benthic assemblages are often eliminated or reduced below the cages (Edgar et al., 2005;Tomassetti et al., 2009;Martinez-Garcia et al., 2013). ...
Article
Organic loading from fish farming constitutes a significant disturbance to marine sediment, normally reducing species abundance and richness and creating disturbed patches in soft-bottom communities. In contrast, floating fish farms harbour a high abundance of invertebrates associated with fouling communities, particularly amphipods. Changes in macrofaunal recolonisation induced by fish farms were researched using amphipod assemblages as a useful representative group. The objectives of this experiment were: (1) to test the effect of fish farms on amphipod colonisation processes in defaunated sediments and (2) to define the influence of surrounding natural and artificial habitats as sources of initial colonisers. Experimental design included 36 plastic trays placed on the sea bottom (25-28. m depth) in fish-farming and control areas and retrieved one month after placement date. Significant differences were found in amphipod assemblage composition in control versus farm sites. While the recolonisation process in control areas depended on the species present in the sediments adjacent to the experimental trays, in fish-farming areas the recolonisation was strongly dependent on the input of amphipods from fouling communities. It is the first time that a spillover effect from fouling communities on floating habitats into the benthos is detected in the coastal areas. If the organic enrichment of aquaculture sediments is moderate, the ecological services of benthic habitats may be balanced, at least partly, by biomass exported from fouling communities on the same fish farms.
... Most of them are considered as opportunistic species, which have small-body size, and grow rapidly in response to a disturbance, especially organic enrichment [1], [5]. [16] found that, there was evidence of macrobenthic recovery fifteen months after fallowing. However, opportunistic species were still dominating, suggesting that the areas were moderately to slightly disturbed at the end of the study. ...
... The settlement of fecal pellets and unused food from fish farms results in accumulation of organic matter on the sea bottom, causing strong modification of the local environment and macrobenthic assemblage changes (Hargrave, 2010;Karakassis and Eleftheriou, 1998;Karakassis et al., 1999Karakassis et al., , 2000. Organic matter in surface sediment is an important source of food for benthic fauna but an overabundance may lead to reduction in species richness, abundance and biomass due to oxygen depletion and buildup of toxic by-products to an anaerobic and ultimately azoic state in heavily farmed or depositional areas; remediation of highly enriched sediments may take several years (Pereira et al., 2004); (Pearson and Rosemberg, 1978). Environmental consequences of aquaculture are site-specific, depending on various factors such as regional temperature, local hydrodynamics, geochemical sediment features, benthic shear, sediment texture and composition, water depth, nutrient loading, reared species, feed type and feeding techniques (Karakassis et al., 2000;Pearson and Black, 2001). ...
... Little published research is available describing field investigations of the environmental impacts of salmonid culture for many of the major growing regions of the world. Most such investigations focus on impacts on macrobenthic invertebrates, a community type amenable to research and one that can undergo extreme change when subjected to high levels of organic enrichment associated with farm operations (Hargrave et al.1997; Karakassis et al. 1999Karakassis et al. , 2000Macleod et al. , 2006Pereira et al. 2004;Pohle et al. 2001;Ritz et al.1989). ...
... El área de influencia alcanza por lo general un area de 250 metros alrededor de las jaulas (Yokohama et al., 2006). El tiempo de recuperación del ecosistema una vez que cesa la deposición de materia procedente de la acuicultura puede alcanzar los dos años (Karakassis et al., 1999; Wildish et al., 1999; Brooks et al., 2003; Macleod et al., 2004; Pereira et al., 2004). ...
Technical Report
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IMPACTO DE LA ACUICULTURA EN EL SECTOR TURÍSTICO DE TENERIFE Angel Luque, José A. Martin García José González Pajuelo Dpto de Biología, Facultad de Ciencias del Mar Universidad de Las Palmas de Gran Canaria RESUMEN Desde sus inicios, la acuicultura se nos ha presentado como una industria limpia y no contaminante, sin embargo, como ocurre en el caso de otras industrias de producción animal intensiva, esta actividad es altamente contaminante ya que genera diversos productos residuales. En el caso de los cultivos de peces en jaulas flotantes localizadas en aguas costeras los vertidos se realizan, directamente sobre la masa de agua en la que se encuentran ubicadas, sin ningún tipo de control. De forma reiterada se informa en los medios de comunicación que se trata de conseguir una producción alternativa de peces, que va a sustituir la extracción por pesca, ya que los caladeros van estando agotados y de esta forma se pueden explotar menos, manteniendo la calidad de la dieta humana, sin embargo esto no es real, las especies cultivadas (dorada, lubina o atún) son carnívoras estrictas y por lo tanto requieren en su alimentación un porcentaje de harina de pescado, de tal forma que cada kilogramo de cultivo de pescado requiere el uso de entre tres o cuatro kilos de harina de pescado, esto es equivalente a que tuviéramos granjas de tigres, leones y leopardos para consumo normal a los que alimentáramos con carne de cerdo o de ternera. Resulta una actividad totalmente insostenible con las actuales especies de cultivo. La acuicultura y la explotación turística de una zona son actividades que compiten entre sí por el uso de las aguas litorales. La ubicación de jaulas flotantes en áreas costeras genera un impacto visual, no sólo por la jaula en sí, sino por todo lo que rodea a esta actividad. Desde el punto de vista físico las jaulas flotantes generan una alteración por sí misma, impidiendo el uso de esa masa de agua con fines recreativos además de disminuir la calidad y transparencia del agua de mar por la presencia de materia particulada. La instalación de jaulas de acuicultura en las costas de Tenerife es una actividad de producción animal que ha aumentado en los últimos años de forma que en el año 2010 se estima una producción de 4000 TM de las especies dorada y lubina. Las jaulas de cultivo tienen un diámetro que oscila de los 9 a los 25 metros y un copo de profundidad variable, de acuerdo con la profundidad en la que estén instaladas. La administración es conocedora del efecto contaminante de estas instalaciones por lo que ha promovido variados planes de ordenación de la actividad en Tenerife durante los últimos años entre los que destacan: en 2002 la creación de “zonas actas para la acuicultura”, en 2006 la “Propuesta de ordenación de la acuicultura del Cabildo de Tenerife” y en 2008 el “Plan regional de ordenación de la acuicultura (PROAC), a las que tenemos que añadir el “Plan de gestión y monitorización ecológica del LIC ES-7020017Punta de Teno– Punta Rasca” en 2005 que dedica una parte importante de su contenido a la regulación de la acuicultura. En todos los documentos se destaca la poca actitud del Oeste de Tenerife para acoger esta actividad, sin embargo, la Viceconsejería de Pesca del Gobierno de Canarias, que es la administración responsable de la concesiones marítimas, informa a Ashotel en Julio de 2009 de la existencia de 20 concesiones de cultivo, todas ellas situadas en el Oeste de Tenerife entre la Punta de Teno y la Punta de Tasca, en los municipios de Santiago del Teide, Adeje y Arona. Los tres municipio suman un total de 100 hoteles y 159 alojamientos extrahoteleros (apartamentos) lo que supone el 40 % de las instalaciones hoteleras y el 49 % de las instalaciones extrahoteleras de Tenerife y en cuanto a plazas representan el 64 % de las plazas hoteleras y el 77,4 % de la plazas extrahoteleras de Tenerife, soportando más del 60 % del turismo de Tenerife. El número de empleos que aporta la acuicultura es de 120 mientras que el de empleos directos producido por la oferta alojativa asciende a mas de 40.000 personas, pero si añadimos el empleo generado por las actividades de ocio (puertos deportivos, barcos, actividades diversas) y el producido por el sector de restauración más todos los sectores implicados podemos alcanzar los 80.000 empleos, siendo uno de los motores de la economía tinerfeña. La degradación del ambiente marino como consecuencia de la acuicultura ha sido observada en numerosas ocasiones. La puesta en funcionamiento de granjas marinas en jaulas flotantes conlleva un gran impacto sobre el ambiente, por el aporte de contaminantes orgánicos que degeneran los fondos marinos y los modifican de forma considerable, desde el punto de vista de sus características físicas, químicas y propiedades biológicas en las zonas ubicadas debajo de las jaulas y en su entorno próximo. En este sentido, el 85% del fósforo, 80-88% del carbono y del 52-95% del nitrógeno añadido al medio marino como alimento para los peces se pierde en el medio como comida desperdiciada y no consumida, excreción y productos fecales. Las descargas medias totales estimadas en Canarias son para una producción de 100 TM de 1680 kg de Fósforo (P) y 12000 kg de Nitrógeno (N) Considerando una producción de peces de 4000 TM para el año 2010 entre todas la instalaciones de acuicultura de Tenerife y que además se encuentran en su totalidad en el LIC Teno-Rasca, esta zona está recibiendo un aporte de 480.000 Kg de nitrógeno y 67.200 kg de fósforo. Ni el nitrógeno ni el fósforo son contaminantes por ellos mismo pero si son los factores que estimular la producción primaria (nutrientes) dando lugar a fuertes incrementos de materia orgánica. Haciendo la equivalencia con el agua residual urbana, las 480 TM de N que pueden aportar las jaulas de acuicultura al medio serían equivalentes a un volumen de agua residual de 9.600.000 m3 y considerando un consumo anual por habitante es de 73 m3 (200 l/habitante x día) equivale a la emisión de nitrógeno al mar de una población de aproximadamente 130.000 habitantes, sin sistema de depuración de agua, ni control sobre los vertidos. Esto, en el caso de Tenerife, es equivalente a un aumento de población del 15% o equivalente a los residuos generados por tres millones de turistas (3 millones de turistas x 9 días de estancia x 0,3 m3 de agua consumida al día x 50g de N/m3 =405 toneladas de N). Podemos afirmar, sin exagerar, que la liberación al medio de nitrógeno y fósforo de las jaulas, permitidas en el Oeste de Tenerife, es bastante superior a la emitida por las 90.000 camas turísticas de los municipios considerados y eso suponiendo una ocupación anual del 100 %. Indudablemente que la comparación de los niveles de contaminación entre la acuicultura y el turismo considerando el valor añadido de ambos en generación de riqueza para Tenerife, exige el cuestionar el modelo de desarrollo de la acuicultura, puesto que a similares niveles de contaminación el turismo genera 700 veces más empleos que la acuicultura. Pero además la acuicultura genera otra gran cantidad de respuestas adversas por distintos factores como la calidad de la columna de agua y sedimentos la competición de las especies cultivadas con las especies salvajes y la disminución de la biodiversidad, aunque la alimentación artificial origine más biota. Mención aparte, por su interés, son las alteraciones en el comportamiento de especies silvestres que pasan a obtener una fuente permanente de alimento ya sea por el pienso sobrante que cae al fondo, el incremento en la producción de algas y plancton debido a los incrementos de N y P, por el efecto atrayente de las jaulas y que da más posibilidades alimenticias a los depredadores o por los escapes ocasionales, mayores o menores, de las especies cultivadas. La modificación del comportamiento afecta a todas las especies, pero, creemos de interés considerar el delfín mular ya que su conservación uno de los objetivos principales de la declaración del LIC (ZEC) marino Teno-Rasca. Los delfines mulares, como el resto de los depredadores superiores, son susceptibles a los cambios que pudiese causar la acuicultura en la distribución y abundancia de sus presas. Diversos proyectos realizados han puesto de manifiesto que los delfines se han acostumbrados a recibir alimento y a dejarse tocar y que su comportamiento puede estar volviéndose más agresivo al competir por el alimento Se destaca en uno de los proyecto que las hembras van acompañadas de sus crías por lo que estas crías pueden habituarse a recibir alimento y no aprender a cazar. Dicho fenómeno ha sido observado en la costa nororiental de Cerdeña, donde la distribución y presencia de delfines mulares se vio claramente alterada tras la construcción de una planta de maricultura con jaulas flotantes para el engorde de doradas y lubinas y que también indirectamente afectan a su estructura social y su comportamiento y además señalan que la presencia de delfines mulares puede provocar daños derivados del estrés al que se ven sometidos los peces cultivados ante un depredador. La acuicultura intensiva varía significativamente de país en país. Sin embargo, todos muestran una serie de características comunes como son la formulación de piensos como fuente de alimento, la aplicación de sustancias agroquímicas, antibióticos y otras sustancias, resultando como consecuencia de ello la presencia de muchas sustancias químicas y contaminantes biológicos en las explotaciones de acuicultura. Estas sustancias provienen del uso de antibióticos, pesticidas, herbicidas, hormonas, anestésicos, pigmentos, minerales y vitaminas. En una revisión realizada por la FAO del uso de antibióticos por los 15 principales países productores de cultivos, que conjuntamente generan el 94% de la producción de acuicultura mundial, se observan el uso de 26 medicamentos, siendo la oxitetraciclina (92% de los países), seguida del cloranfenicol (69%) y el ácido oxolínico (69%) los antibióticos más comúnmente utilizados. El uso intensivo de antibióticos, como profilácticos o como medida terapéutica, en la acuicultura ha generado la aparición de elevadas cantidades de antibióticos en la sangre, músculos e hígado de los animales cultivados y los salvajes. Se ha comprobado, por otra parte, que el uso de determinados sustancias que se utilizan para el cultivo de peces así como algunos antibióticos tienen un carácter enormemente tóxico para algunos organismos constituyente de los ecosistemas marinos como los anfípodos, los poliquetos y las estrellas de mar que se localizan debajo o en zonas próximas a las jaulas de cultivos, ya que estas sustancias actúan paralizando el sistema neuromuscular de dichos animales. Una de estas sustancias es el Cloranfenicol que fue evaluado por JECFA (Joint FAO/WHO Expert Committee on Food Additives) en varias ocasiones y que han indicado que esta sustancias y sus metabolitos son genotóxicos, embrión-fetotóxicos, y cancerígenos potenciales en humanos. Un gran número de estudios ha constatado elevados niveles de resistencia bacteriana a los antibióticos alrededor de las instalaciones de cultivos marinos. La resistencia bacteriana se alcanza mediante mutaciones en el DNA bacteriano o a través de mecanismos genéticos de transferencia horizontal hacia otras bacterias. La relación entre el uso de antibióticos en la acuicultura y la generación de resistencia bacteriana ha sido demostrada en muchas ocasiones, observándose casos de resistencia a más de tres antibióticos de forma simultánea. Como consecuencia de ello son una de las mayores preocupaciones de la Organización Mundial de la Salud (OMS). La resistencia bacteriana a antibioticos puede ser genéticamente transmitida desde bacterias inofensivas o bacterias residentes en los sedimentos de los cultivos de peces a bacterias patógenas para el hombre. La OMS señala que el uso de sustancias antimicrobianas en la acuicultura se constituye como un vehículo de diseminación de cepas bacterianas y genes resistentes a los antibióticos y como uno de los principales focos emergentes de riesgo antimicrobiano. Se ha comprobado, que la instalación de jaulas flotantes y de granjas para el cultivo de peces conlleva un masivo aumento de la presencia de microorganismos, en ocasiones patógenos, tales como bacterias, protozoos y parásitos que infectan a los animales cultivados Además, algunos microorganismos que se desarrollan en estos ambientes generados por la acuicultura son directamente dañinos para los animales cultivados y para los salvajes a través de toxinas biológicas y neurológicas. Este aumento de los microorganismos patógenos en el agua ha ocasionado incluso infecciones a humanos como consecuencia del consumo de especies cultivadas llegando a producir en algunos casos meninginitis por estreptococos. Las enfermedades y los parásitos de las especies cultivadas también pueden afectar a las especies salvajes que no estaban en contacto con estos parásitos al haber sido introducidos en el medio ambiente por los cultivos. Las aguas de las instalaciones de acuicultura y en su entorno contienen en muchas ocasiones numerosos metales pesados y productos químicos orgánicos incluyendo dibenzodioxinas policloradas (PCDDs) y dibenzofuranos (PCDFs), bifenilos policlorados (PCBs), y éteres difenilos polibromados (PBDEs). Los peces de estas instalaciones pueden contener altos niveles de contaminantes en sus tejidos y si se considera que los organismos acuáticos que se localizan en el área, como los moluscos y los crustáceos, pueden acumular estas sustancias pudiendo llegar a afectar al hombre por la ingestión de esos animales salvajes Los productos agroquímicos utilizados en la acuicultura incluyen herbicidas, pesticidas, antifúngicos, desinfectantes, fertilizantes y compuestos para el tratamiento de aguas. Una fuente adicional son los productos utilizados en agricultura que llegan a las aguas de las instalaciones de cultivo. El nivel de estos contaminantes es tan importante que determinados países han impuesto análisis para los productos procedentes de la acuicultura. Entre ellos destaca la FDA en Estados Unidos, (United States Food and Drug Administration) que somete a análisis las importaciones de peces y crustáceos procedentes de cultivos para detectar la presencia, entre otros, de antifúngicos ya que estas sustancias químicas son cancerígenos y mutágenos que han sido prohibidos en EEUU, Canadá y la Unión Europea. Aunque su uso ya está prohibido, la exposición humana a estos productos puede ocurrir por el consumo de animales salvajes, que hayan crecido en el entorno, ya que se mantienen en los sedimentos. En los últimos años muchos estudios se han centrado en la exposición a varios compuestos orgánicos organohalogenados resultado del consumo de producto provenientes de la acuicultura. Estos productos incluyen PCDDs y PCDFs (conocidos comúnmente como dioxinas), PCBs, y PBDEs. Se han desarrollado estudios comparando diferentes contaminantes organohalogenados (dioxinas, PCB, PBDE, organofosfatos) entre salmón de cultivo y salvaje observando mayores concentraciones en los tejidos del animal procedente de cultivo y lo mismo ha sido encontrado en la lubina. En algunos estudios se ha logrado seguir la trazabilidad de estos compuestos observando que su procedencia tenía el origen en el pienso de los animales de las instalaciones de acuicultura. Además las tecnologías emergentes, incluyen el desarrollo de peces transgénicos (organismo modificados genéticamente). El primer animal transgénico se desarrolló hace 25 años y en la actualidad existen más de treinta y cinco especies que han sido modificadas por ingeniería genética incluyendo el salmón atlántico. Estos animales transgénicos producen toda una serie de proteínas que no existen en los animales no transgénicos y cuyos efectos son aumentar el crecimiento, incrementar la resistencia a patógenos, incrementar la resistencia al calentamiento de las aguas y mejoras las cualidades nutricionales de los animales. Los animales transgénicos no han sido aprobados para el consumo humano en los países productores. Sin embargo aunque no presenten riesgos para la salud humana, su efecto sobre el medio natural podría ser devastador, ya que sus condiciones de resistencia a enfermedades y mayores tasas de crecimiento pueden alterar completamente los ecosistemas si existen liberaciones accidentales al medio, tan frecuente en la acuicultura.
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Eelgrass ( Zostera marina ) beds provide important habitat and food sources for a wide range of associated species both above- and belowground. Organic enrichment and nutrient loading from anthropogenic sources can change eelgrass canopy structure and macroinfauna community composition, making them important indicators of ecosystem health. In Atlantic Canada, there is growing concern about the impacts of finfish aquaculture on eelgrass habitats. To quantify these effects, we examined differences in environmental parameters, eelgrass bed structure and macroinfauna communities at increasing distances from a finfish farm in Port Mouton Bay, Nova Scotia and a reference site in an adjacent bay. We also compared the results to recently published large-scale survey results from the Atlantic coast. Results indicate increased organic enrichment and decreased eelgrass biomass, shoot density, and macroinfauna biomass closer to the farm. Moreover, community structure significantly differed between sites with some sensitive species disappearing while tolerant species increased closer to the farm. Changes in the macroinfauna community could be linked to observed differences in environmental and eelgrass bed variables. Our results provide new insights into the impacts of finfish aquaculture on eelgrass habitats in Atlantic Canada. We discuss possible assessment and monitoring metrics that would enable managers and regulators to evaluate the risk and potential changes to eelgrass habitat as a result of finfish aquaculture.
Preprint
Full-text available
Eelgrass ( Zostera marina ) beds provide important habitat and food sources for a wide range of associated species both above- and belowground. Organic enrichment and nutrient loading from anthropogenic sources can change eelgrass canopy structure and macroinfauna community composition, making them important indicators of ecosystem health. In Atlantic Canada, there is growing concern about the impacts of finfish aquaculture on eelgrass habitats. To quantify these effects, we examined differences in environmental parameters, eelgrass bed structure and macroinfauna communities at increasing distances from a finfish farm in Port Mouton Bay, Nova Scotia and a reference site in an adjacent bay. We also compared the results to recently published large-scale survey results from the Atlantic coast. Results indicate increased organic enrichment and decreased eelgrass biomass, shoot density, and macroinfauna biomass closer to the farm. Moreover, community structure significantly differed between sites with some sensitive species disappearing while tolerant species increased closer to the farm. Changes in the macroinfauna community could be linked to observed differences in environmental and eelgrass bed variables. Our results provide new insights into the impacts of finfish aquaculture on eelgrass habitats in Atlantic Canada. We discuss possible assessment and monitoring metrics that would enable managers and regulators to evaluate the risk and potential changes to eelgrass habitat as a result of finfish aquaculture.
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The chitin synthesis inhibitor teflubenzuron (TFB) is a feed antiparasitic agents used to impede molting of the salmon lice, an ecto-parasite that severely affects the salmon industry. Low absorption of oral administered TFB may cause elevated concentrations in the feces discharged from the salmon into the benthic environment. The polychaete Capitella sp. are often dominant in such habitats and consume organic waste deposited on the sediment. In the present study, Capitella sp. were exposed to doses of TFB in salmon feed of 1, 2 and 4 g TFB kg⁻¹ (0 g TFB kg⁻¹ in control group) over an experimental period of 32 days. Cumulative mortality was 12%–15% in both treatment groups with 1 and 2 g TFB kg⁻¹ and reached 27% in the group with 4 g TFB kg⁻¹. Only the highest dose (4 g TFB kg⁻¹) negatively affected feed intake, growth and respiration of the polychaetes while food conversion efficiency was not affected. At the end of the experiment, the concentrations of TFB in the Capitella sp. were high, in the range of 9.24–10.32 μg g⁻¹ for the three treatment groups. It was suggested that a maximum level of absorption rate was reached, also for the lowest dose. High concentrations of TFB in the Capitella sp. might pose a risk to crustaceans that forage for polychaetes in the vicinity of fish farms. We conclude that the effects of TFB on Capitella sp. may therefore primarily be to the predators rather than the Capitella sp.
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Fin-fish production continues to expand with the switch in diet from traditional fish meals and oils to terrestrial sourced components. Terrestrial crops can be traced into the marine environment due to their high abundance of C18 fatty acids (FA). Here we compare two FA extraction techniques on coastal sediments; Folch lipid extraction and direct methylation. We found differences in the FA classes which could be extracted using these methods, and that direct methylation extracted more of the terrestrial biomarkers. We applied the direct methylation method to detect organic waste dispersal from a fin-fish farm along a transect in sedimentation and sediment samples across a production cycle, along with polychaetes collected during post-peak production. We traced organic waste from the fin-fish farm as far as 1100 m by mid production. Furthermore, we found polychaetes to have FA profiles reflective of the sediment, indicating they are assimilating aquaculture waste.
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Eelgrass ( Zostera marina ) has been designated an Ecologically Significant Species in Atlantic Canada. The development and rapid expansion of netpen finfish aquaculture into sensitive coastal habitats has raised concerns about the impacts of finfish aquaculture on eelgrass habitats. To date, no studies have been done in Atlantic Canada to examine these impacts or to identify potential monitoring variables that would aid in the development of specific conservation and management objectives. As a first step in addressing this gap, we examined differences in environmental variables, eelgrass bed structure and macroinfauna communities at increasing distances from a finfish farm in Port Mouton Bay, a reference site in adjacent Port Joli Bay, and published survey results from other sites without finfish farms along the Atlantic Coast of Nova Scotia. Drawing on research done elsewhere and our results, we then identified possible metrics for assessing and monitoring local impacts of finfish aquaculture on eelgrass habitats. Our results suggest some nutrient and organic enrichment, higher epiphyte loads, lower eelgrass cover and biomass, and lower macroinfauna biomass closer to the farm. Moreover, community structure significantly differed between sites with some species increasing and others decreasing closer to the farm. Changes in the macroinfauna community could be linked to observed differences in environmental and eelgrass bed variables. These results provide new insights into the potential impacts of finfish aquaculture on eelgrass habitats in Atlantic Canada. We recommend a suite of measures for assessment and monitoring that take into account response time to disturbance and account for different levels of eelgrass organizational response (from physiological to community).
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This study investigated sediment oxygen consumption rates and geochemical characteristics of sediment in hypoxic area of the Gamak Bay based on the chamber experiments and geochemical analyses. The organic carbon contents of surface sediment in the Gamak Bay showed that the inner bay area has higher organic carbon content than those of the outer bay. They toward the outer bay, contents dropped off. The vertical profiles of calcium carbonate (CaCO_3) content at piston core sediment assumed that the hypoxia have been frequently occurred during past century in the northern inner bay. The benthic chamber experiments were conducted in February, May, August and November 2010, 2011 in the hypoxic area of the Gamak Bay. In the sediment incubation experiment with chamber at site C3 in the northern inner bay and site C17 in the southern outer bay, the sediment oxygen consumption rate ranged from 3.98mmol\;m^{-2}d^{-1} to 12.43mmol\;m^{-2}d^{-1} and 3.28mmol\;m^{-2}d^{-1} to 8.18mmol\;m^{-2}d^{-1}, respectively. When the oxygen was completely depleted, the toxic hydrogen sulfide was released with 1.38mmol\;m^{-2}d^{-1} and 1.3mmol\;m^{-2}d^{-1}, respectively.
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In this study Moringa oleifera leaves (biosorbent) is used for Cadmium (II) removal from water as a natural alternative for synthetic sorbents. Synthetic water was used to find optimum conditions for water treatment using biosorbent. The effect of biosorbent dosage and particle size, contact time, and pH effect were studied. Atomic Absorption Spectroscopy (AAS) was used to monitor the Cd (II) concentration before and after treatment with biosorbent. Fourier Transform Infrared Spectroscopy (FTIR) was used to monitor biosorbent structure changes before and after loading with Cd (II). Many parameters were studied such as: dosage of biosorbent (1 – 10 g/L), contact time (2 – 20 min), particle size (2 mm, 1 mm, 500 µm, 250 µm, and <250 µm), pH range (4-10), and Cd (II) concentrations (1, 3, 5, and 7 ppm). The statistical analysis of studied parameters showed that all parameters has an effect on Cd (II) removal with p values <0.05 except pH. FTIR result showed changes in the finger print area of biosorbent functional groups due to adsorption of Cd (II). As a conclusion, Moringa oleifera leaves can be used as an effective, low cost, and environmentally friendly biosorbent for the removal of Cd (II) from water.
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An environmental recovery study was carried out after the cessation of a gilt-head seabream farm off the Mediterranean coast of Spain. Physicochemical variables of sediments, in situ benthic fluxes of oxygen and nutrients, and benthic macrofauna were measured in the farming area and at a control station. Five sampling campaigns were done, one before the closure and the others at 1, 3, 9, and 24 mo after cessation. Benthic flux of ammonium was the first variable to recover, followed by benthic fluxes of phosphate and dissolved oxygen and percentage organic matter in the sediments, which 3 mo after the cessation of farming already showed levels similar to those in the control station. Nine months after cessation, the other abiotic variables of the sediments disturbed by the activity had recovered, such as percentage coarse fraction, total phosphorus concentrations, and redox potential measurements. The recovery of the macrofauna was slower than the abiotic variables. Three months after cessation, Capitella capitata abundance had reduced drastically in the farming area, but similar specific richness levels were not observed between the two sampled zones until 2 yr after farming cessation.
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Excessive input of organic matters from fish cage farming has been considered as one of the major factors disturbing benthic ecosystem, especially in semi-enclosed coastal waters. Recently offshore aquaculture in the vicinity of Jeju-do has been introduced to minimize that kind of negative impact. This study was conducted to investigate the ecological impacts of offshore aquaculture on the macrobenthic polychaete communities. A total of ten sampling works were carried out for 28 months, spanning from 10 days after starting giving feed to 3 months after stopping giving feed. During the study period, mean current velocity was quite strong with the range of 50 cm/s to 70 cm/s. TOC of surface sediment was constantly low. Significant changes in polychaete community were detected just three months after starting giving feed, which were the increase of the number of species and density at all stations. Up to 18 months after the start of farming, the amount of feed provided played an important role in the fluctuation of the number of species and density, especially at 0 m and 10 m stations. After reducing the amount of feed provided, dominance of some opportunistic species within 10 m distance from fish cages still lasted to the end of aquaculture. However, opportunistic species disappeared 3 months after the end of farming, which indicated the sign of recovery from the disturbance. From these results, the amount of food input and the period of cultivation were critical factors disturbing polychaete community and ensuing changes in this offshore and oligotrophic waters as well. In addition, study on the changes of polychaete community structure before and after fish farming showed more detailed changes in benthic ecological state than geochemical approach did.
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We have used changes in oxygen uptake of sediment cores incubated in the laboratory and receiving no particulate input to examine the utilization of labile organic carbon by the benthos. A model is described that predicts a decline in sediment oxygen consumption after primary labile organic carbon (G01) is depleted. Oxygen consumption by cores taken from an intertidal sandflat in Nova Scotia and incubated in darkness (11-13'C) declined after about two months. Go-organic carbon was estimated as percent of total sediment carbon (Gr) in the upper 1 cm of sediment. Anaerobic metabolism (based on CO2 production), a significant portion of community metabolism, increased rather than declined during the incubations. Similar calculations were performed using published data on cores from Narragansett Bay. At this location, organic matter in the Gs1 fraction was 5 percent of Ga. A less labile organic carbon fraction (Gs2) was estimated to be 44% of Gr based on declining oxygen consumption after 27 days. Refractory carbon estimated by difference was 51 percent of total carbon. Our results suggest that there is short-term decoupling between organic matter metabolism in the sediment and the supply from the water column. When organic supply to the sediment is interrupted, there is a small pool of carbon in the sediment that can maintain benthic community metabolism for a period of weeks to months.
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Quantitative sampling of the fauna was made in 1971 and 1972 to complement previous data about the faunal recovery after the cessation of the sulphite pulp mill in 1966. In 1972 the succession had approached a final phase in which the fauna had regained a composition similar to that found forty years earlier. The benthic faunal increment, expressed as dry weight, in Saltkallefjord between 1968 and 71 was roughly estimated to 20% and the yearly production to 70-80 tons on this 4.4 km2 area. Different indices have been used to describe the communities and the diversity. The succession showed a logistic pattern similar to population growth curves.
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Benthic fluxes of dissolved oxygen and ammonium were measured at bi-weekly to monthly intervals during 1990-91 proximate to and under an array of pens holding Atlantic salmon Salmo salar Linn. in L'Etang Inlet, a macrotidal embayment in the Bay of Fundy, Canada. Hierarchical clustering of data indicated that the 7 stations could be divided into 3 groups (3 stations under the pen array, 2 at the perimeter of the array and 2 away from pens). Average rates of oxygen uptake and ammonium release for the 3 stations under the pens were 4 and 27 times higher, respectively, than values at the 2 stations distant from the cages. Maximum average rates of ammonium release (38 mmol m-2 d-1) in late July and oxygen uptake (99 mmol m-2 d-1) in early September for stations under the pens coincided with maximum water temperatures and sediment sulfide accumulation, respectively. Negative redox (Eh) potentials (< 0 mV) and reduced numbers of benthic polychaetes Capitella spp. also occurred in sediments under pens between mid-July and September. Values of > 100 mM S= in sediment pore water during September could have been toxic to benthic fauna as well as to heterotrophic bacteria that produce substrates utilized by sulfate-reducing bacteria.
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Total sediment metabolism (measured CO2 production across the sediment-water interface) and sulfate reduction (measured by S-35 technique) was examined in the organic rich sediments around a marine fish cage farm in shallow Danish waters. Sediment metabolism beneath the net cages was about 10 times higher during the farming period (525 to 619 mmol CO2 m-2 d-1) than at an unaffected control station (24 to 70 mmol CO2 m-2 d-1). Depth-integrated sulfate reduction rates (0 to 10 cm) beneath the net cages (234 to 310 mmol m-2 d-1) could support 75 to 118 % of the measured CO2 production across the sediment-water interface. At the end of the farming period and during winter (no fish farming), sediment metabolism and sulfate reduction rates decreased considerably (33 to 77 mmol CO2 m-2 d-1), but both rates were still elevated compared to the control station, indicating that the impact of fish farming on the anaerobic mineralization was prolonged. Nearly all reduced S-35 label was recovered in the acid volatile fraction (AVS). During decreasing sulfate reduction rates, however, the chromium reducible fraction (CRS) became more important in the upper oxidized sediment layers. Pore water profiles of mineralization products (HCO3- and NH4+) reflected the rapid decomposition and showed a preferential regeneration of nitrogen throughout fall and early spring.
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Phosphorus fluxes were measured in a marine fish cage farm in the Gullmar Fjord, western Sweden. The measured fluxes included fish food, juveniles, harvest, fish loss (dead fish and escapers), sedimentation from the cages and benthic solute release (in situ). Two different types of mass balances were constructed. The flux method was based on seasonal input of fish food and juveniles, sedimentation and removal by harvest, fish loss and benthic fluxes. Mass balances according to the flux method were constructed for each of 2 consecutive growing seasons. The accumulation method was based on total input of phosphorus through fish food and juveniles, removal by harvest and fish loss, and net accumulation in the sediment over 7 growing seasons. Both types of mass balances gave similar results. Of the total phosphorus input to the farm, 17 to 19% was recovered in harvest, fish loss constituted 1 to 4%, and 78 to 82% was lost to the environment. The environmental loss of phosphorus for each ton of fish produced was 22.4 kg (1985), 19.6 kg (1986) and 21.9 kg (1980 to 1986). Of the loss to the environment, 34 to 41% was in dissolved form and 59 to 66% was accumulated in the sediment. On a seasonal basis, the benthic flux transferred 4 to 8% of the sedimented phosphorus back to the overlying water. This constituted about 1% of the total phosphorus content in the sediment derived from the fish farm.
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The environmental impacts of salmon net-pen aquaculture on the benthic environment were investigated at a commercial fish farm located in coastal Maine waters. This site has a sandy mud bottom and low current velocities, is subjected to episodic sediment resuspension, and way in production for 3 yr prior to this study: We examined both the increase in carbon flux to the benthos caused by the net-pen and the effects of the elevated flux on sediment biogeochemistry and the microbenthic communities. The experimental design involved the establishment of two study sites, an ambient site ca. 100 m from the net-pen and a treatment site around the pen. Sediment traps deployed 1 m above the sediment-water interface indicated that carbon flux to the benthos was increased 1-fold to 6-fold (to a maximum of 5 g m−2d−1) at the edge of the net-pen with little or no increase in carbon flux 10 m from the pen. Unlike carbon flux rates, sediment organic matter inventories showed a complex pattern of change over time. Mineral surface area, organic carbon and nitrogen, digestible protein, and sterol content were initially (April 1991) lower beneath the pen than in ambient sediments. During 1991 ambient sediment accumulated organic matter until July after which it decreased, to a low during November. In contrast, organic matter inventories of sediment beneath the pen remained low until July and then increased to a high during November. These latter gains were associated with the development of bacterial mats at the sediment-water interface. Beneath the pen, microbial and macrofaunal communities were shifted toward those commonly associated with organic enrichment but seasonal trends and storm-related resuspension events also significantly affected these sediment communities. When abundant, most epibenthic organisms were more numerous near the pen than in adjacent ambient areas. These results suggest that net-pen aquaculture can alter the benthic ecosystem in Maine Coastal waters but indicate that the effects are spatially limited.
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The polychaete fauna of a sandy intertidal habitat receiving effluent from a sewage treatment plant was compared to that of a control site. The total number of individuals, total biomass, and average species numbers were significantly greater at the sewage-affected site. The response of individual species to nutrient enrichment varied. Some species showed significantly greater numbers of individuals at the sewage-affected site while other species' densities showed no difference. All species maintained greater biomass at the enriched site, most biomass differences were significant. Those species which did not show density differences between sites tended to have the greatest difference in average weight per individual. In general, species with either benthic development or some form of brooding behavior were best able to exploit the enriched condition by increased densities, or greater average biomass per individual. It was concluded that for moderate increases in nutrient concentrations, benthic productivity will be most enhanced in those sediments with very low concentrations of fine sized particles.
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After the removal of fish cages at an intensive aquaculture site, the sedimentary environment was monitored over 23 mo for redox potential, total organic carbon and nitrogen, total phosphorus, algal pigments and macrofauna. Three sampling stations were established: one under the previous location of the cages (R-0), a second one (R-10) at 10 m distance from the edge of the cages and a control site (R-c) at >1 km distance. At both stations near the farming site the sediment was initially found to be anoxic and overlain by a highly organic black layer. Most geochemical variables at Stn R-10 attained values close to those at Stn R-c within 11 mo. Large fluctuations in the values of most variables were observed at Stn R-0 over the 23 mo, indicating that the environment had not fully recovered before the end of the observations. Similar results were obtained from the macrofaunal analysis, which revealed that after 23 mo a high proportion of benthic fauna at Stn R-0 was still composed of opportunistic species; abundance biomass and species composition showed marked successive changes in the direction of succession. This regression was attributed to a secondary disturbance due to a benthic algal bloom, caused by the seasonal release of nutrients from the farm sediment. It is concluded that the recovery process of heavily enriched benthos in a dynamic coastal environment is subject to the influence of different factors, resulting in progress and regression, and therefore the succession model proposed by Pearson & Rosenberg (1978; Oceanogr Mar Biol Annu Rev 16:229-311) may not be applicable in the early stages of succession.
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In the early 1980s, a strategy for graphical representation of multivariate (multi-species) abundance data was introduced into marine ecology by, among others, Field, et al. (1982). A decade on, it is instructive to: (i) identify which elements of this often-quoted strategy have proved most useful in practical assessment of community change resulting from pollution impact; and (ii) ask to what extent evolution of techniques in the intervening years has added self-consistency and comprehensiveness to the approach. The pivotal concept has proved to be that of a biologically-relevant definition of similarity of two samples, and its utilization mainly in simple rank form, for example ‘sample A is more similar to sample B than it is to sample C’. Statistical assumptions about the data are thus minimized and the resulting non-parametric techniques will be of very general applicability. From such a starting point, a unified framework needs to encompass: (i) the display of community patterns through clustering and ordination of samples; (ii) identification of species principally responsible for determining sample groupings; (iii) statistical tests for differences in space and time (multivariate analogues of analysis of variance, based on rank similarities); and (iv) the linking of community differences to patterns in the physical and chemical environment (the latter also dictated by rank similarities between samples). Techniques are described that bring such a framework into place, and areas in which problems remain are identified. Accumulated practical experience with these methods is discussed, in particular applications to marine benthos, and it is concluded that they have much to offer practitioners of environmental impact studies on communities.
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In Loch Sween, three thalassinidean shrimps, Callianassa subterranea, Jaxea nocturna and Upogebia stellata, and an echiuran worm, Maxmuelleria lankesteri were identified as part of the megafaunal community. Mechanisms of bioturbation by these species were examined. Quantitative measurements of particulate and fluid movement are given for selected species and related to population density in the field in order to assess the contribution of each to bioturbation rates. Preliminary bioturbation data are also presented for Thalassema thalassemum from the Firth of Clyde. Effects of bioturbation by each of the five species are contrasted and the influence of sedimentary organic carbon upon bioturbatory activity is discussed.
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Stable C isotope measurement in combination with analysis of benthic macrofaunal communities were used to trace the dispersion and effects of solid organic waste derived from a fish cage on marine sediments. The proportion of cage-derived organic C to total organic C in the sediment decreased with increasing distance from a fish cage. A highly organically enriched zone under the cage was characterized by >75% fish cage-derived organic C in the sediment, a semi-enriched zone under the cage was characterizaed characterized by 60% and a lightly enriched zone (> 60 m) by ≈ 40%. Measurable effects of farm organic waste on organisms extended from under the cage to between 10 and 30 m from it. Macrobenthic communities under the cage and 10 m from the cage showed signs of moderate disturbance whereas those from 30 to 150 m appeared undisturbed.
Article
The recovery of benthic communities has been studied continuously since the closure of a sulphite pulp mill in 1966. The previous, increasing organic enrichment in the estuary had deteriorated the marine environment and reduced the fauna over large areas. The succession of the macrobenthic communities to a level where the recovery process was indistinguishable from annual fluctuations took about 8 yr. By then the composition of the community was similar to that recorded 40 yr earlier. The successional changes in number of species, individuals and biomass are illustrated for the total fauna as well as for dominating groups. The sequential changes of some numerically dominant populations showed a bell shaped curve pattern. During the first years after pollution abatement, when polychaetes dominated, these population changes were drastic but evened out in later seral stages. The role of larval recruitment in succession is discussed. Three diversity indices were used to assess the community structure: Shannon's formula, its measurement of evenness, and Sanders' rarefaction technique. As tools for assessing pollution or recovery, the two former had to be used with care, as the highest values were recorded at the beginning of the recovery process when the individuals found were few but evenly distributed among the few species present. The rarefaction technique and the measure of species richness were more satisfactory for this kind of assessment.
Article
During 1968-70, the recovery of the benthic macrofauna was investigated at 53 stations in Saltkällefjord, an inner branch of Gullmarsfjord on the west coast of Sweden. Physico-chemical analyses have shown that the water quality in Saltkällefjord improved as a result of reduced waste water discharge subsequent to discontinuance of production of sulphite pulp in 1966. After 1968, the benthic macrofauna has colonized fjord areas which earlier in the 1960's were azoic, or occupied by a poor fauna only. During May-October 1969, a successive monthly increase of the number of species appeared in these areas. Classification of some species in the succession is subject to discussion. /// В течение 1968-70гг. исследовали восстановление бентосной макрофауны в 53 стациях во фьорде Салткелле - внутренней ветви фьорда Гуллмарс на зарадном побепежье Швеции. Физико-химические анализы показали, что свойства воды во фьорде Салткелле обусловлены недостаточным спуском сточной воды вследствие чего была нарушена продукция сульфитной пульпы в 1966г. После 1968г. бентосная макрофауна заселила территорию фьорда, которая в 60-х годах была азоичной либо заселена очень бадно. В маесентябре 1969г. наблюдалось постеленное ежемесячное увеличение количе ства видов, заселяющих эти воды. Обсуждается классификация отдельных видов в данной сукцессии.
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The main biological effects on the sublittoral benthic communities after the Amoco Cadiz oil spill may be summarized as follows:. At the beginning, the oil severely affects the fine and very fine sand communities. Little disturbance is found in the sandy-mud community, in spite of an important contamination. Mortality is selective, affecting only a limited number of species. The extent of total disturbance varies from place to place in one community, and even more from community to community along the sediment gradient. Presumably there are two causes for these variations in disturbance; the mortality in sensitive species may vary from one place to another, e.g. because of differences in immediate pollution, and the relative abundance of sensitive species varies from one place to another. After the initial disturbance, no further periods of massive mortality in adults occurred, but the recruitment in some species continued to be affected during one or more years after the oil spill. This effect was relatively more important in sediments with high residual concentrations of oil. In most cases, affected or eliminated species start recolonization during the second year after the oil spill. The insular distribution of part of the affected or eliminated species lacking a pelagic larval life delays their reintroduction. Most species not affected by the initial stress continued to exhibit normal annual density cycles. Some species, however, mostly Capitellidae and Cirratulidae, showed population increases that lasted one or more density cycles and began at different times, probably indicating the first steps of a succession. This occurs either after an important disturbance of other species (the studied communities of fine and very fine sands) or after a slight disturbance (sandy-mud community).
Article
Reduction in pollution load to Iddefjord has lead to a more diverse community on the sublittoral rocky bottom at two sites at 7 and 17 m depth from 1978 to 1980. The changes were confirmed by fixed-site stereophotography. The sites were initially dominated by a single species, Polydora ciliata, which was then partially replaced by several other species, particularly Mytilus edulis and Ciona intestinalis. It is suggested that improved water quality indirectly effected predation and natural succession.
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Two methods are described for determination of organic carbon, inorganic carbon, and total nitrogen in sediments, sediment trap materials, and plankton. Both methods discriminate organic and inorganic carbon by acidification, avoid losses of acid-soluble organic and inorganic matter, and utilize an automated CHN analyzer for all elemental determinations. Short-term precisions for organic carbon and total nitrogen are about +-1% of the measured value with blank levels less than 1.5 microgrammes for each element.-Author
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Following cessation of sewage sludge disposal at a site of 2km from Garroch Head, Isle of Bute, Firth of Clyde (Scotland), a study of the recovery of the benthic environment was undertaken. A reappraisal of data obtained in 1971, whilst the site was still actively in use, was undertaken. The benthic community has shown a marked recovery and now approaches what should be considered as normal for this slightly enriched area. (See also 92L/08292) -from Authors
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Between 1994 and 1999, impact on the benthic fauna has been evaluated in two areas with intensive salmon net-pen aquaculture (Lime Kiln Bay, Bliss Harbour). A third embayment (Deadmans Harbour), which lacked significant aquaculture activity, served as a reference site. Changes in benthic community structure were investigated using multivariate, distributional, and univariate analyses. Such changes reflect cumulative stress from various sources, including organic enrichment and chemical therapeutants. Changes at the Deadmans Harbour reference site indicated a general improvement in ecosystem quality during the study period. Lime Kiln Bay experienced an increase in aquaculture activity during the first few years, followed by a complete cessation in 1998. Analyses indicated increased biological stress on the benthic community, suggesting major environmental alterations did take place in that bay. Diversity declined significantly between 1994 and 1995, with a corresponding significant increase in sediment organic content. Analysis of indicator species corroborated the enrichment trend. Sedimentary microbial biomass and organic matter concentrations decreased from 1997 to 1999, reflecting the cessation of fish farming, but the benthos did not recover during this period. It is concluded that benthic impact in Lime Kiln Bay persisted until 1999 even though organic loading decreased. Enrichment levels in Bliss Harbour were elevated from the beginning of the study onwards and the impact persisted throughout the study. The observed differences in community structure within the three embayments were not attributable to differences in sediment types, temperature, salinity, or water depth.
Article
Laboratory study of the bacterial decomposition of Long Island Sound plankton in oxygenated seawater over a period of 2 years shows that the organic material undergoes decomposition via first-order kinetics and can be divided into two decomposable fractions, of considerably different reactivity, and a nonmetabolized fraction. This planktonic material, after undergoing varying degrees of oxic degradation, was added in the laboratory to anoxic sediment taken from a depth of 1 m at the NWC site of Long Island Sound and the rate of bacterial sulfate reduction in the sediment measured by the ³⁵S radiotracer technique. The stimulated rate of sulfate reduction was in direct proportion to the amount of planktonic carbon added. This provides direct confirmation of the first-order decomposition, or G model, for marine sediments and proves that the in situ rate of sulfate reduction is organic-matter limited. Slower sulfate reduction rates resulted when oxically degraded plankton rather than fresh plankton was added, and the results confirm the presence of the same two fractions of organic matter deduced from the oxic degradation studies. Near-surface Long Island Sound sediment, which already contains abundant readily decomposable organic matter, was also subjected to anoxic decomposition by bacterial sulfate reduction. The decrease in sulfate reduction rate with time parallels decreases in the amount of organic matter, and these results also indicate the presence of two fractions of organic carbon of distinctly different reactivity. From plots of the log of reduction rate vs. time two first-order rate constants were obtained that agree well with those derived from the plankton addition experiment. Together, the two experiments confirm the use of a simple multi-first-order rate law for organic matter decomposition in marine sediments.
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Infections of Lepeophtheirus salmonis (Krøyer, 1837) and Caligus elongates Nordmann, 1832 were monitored over a 20-month period on four marine Atlantic salmon, Salmo salar L., farms in Scotland. Three farms were fallowed between harvesting and restocking, and thus, contained only one year class of fish at a time. The fourth site was not fallowed and contained two year classes of fish. Results show that fallowing led to low numbers of L. salmonis on newly introduced fish for several months after stocking, with much less need to use chemotherapy. New fish in the non-fallowed site became very rapidly infected with L. salmonis and required chemotherapy within 2 months of stocking. Fallowing did not appear to be effective in restricting the abundance of C. elongatus. Longer periods of fallowing were more effective in controlling lice numbers.
Article
The experimental addition of different concentrations of sewage sludge to clean marine deposits resulted in a degradation of the sediments and a modified benthic macrofauna. The addition of a large amount of sludge (100 l·m−2·a−1) resulted in a sparse Capitella dominated fauna of low density and high biomass. The lower amount (50 l·m−2·a−1) allowed the presence of a normal fauna but of an enhanced abundance and biomass. Though recovery was good there was evidence that the addition of large amounts of sludge had lasting toxic effects. Comparisons of the results of these experiments with the effects observed in sludge dumping grounds are made and the significance of the different input levels in a marine ecosystem is discussed.
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Analysis of material collected in settlement traps at regular intervals over a period of a year gave an estimate of the annual organic input to the bottom sediment of about 28 gC/m2 year, which is a little less than one third of the primary production in the overlying water column. The aerobic benthic community metabolism, estimated from in situ respiration measurements, was not significantly different from the carbon input. The rate of release of ammonia from the sediment was also measured in situ and would be sufficient to supply the greater part of the required input of inorganic nitrogen for photosynthesis in the water column.
Article
The response of infaunal macrobenthic communities beneath salmonid seacages to solid organic wastes (food pellets and fish excreta) was tested by means of the ABC-method (abundance, biomass comparison method: Warwick 1986) on samples collected from the SAFCOL seafarm at Badger Cove, southeast Tasmania, from February to July 1988. The intermittent nature of the addition of organic waste allowed us to monitor decline and recovery of the macrofauna, i.e., harvesting of a cage permitted a period of recovery whilst restocking precipitated a decline. The ABC-method proved to be a sensitive indicator of community health. Under a normal feeding regime the macrofaunal community structure indicated a moderately disturbed condition. Only 7 wk after the cage was harvested, species richness had increased markedly and the community adopted an undisturbed condition. Further improvement was apparent 14 wk post-harvest. Similarly, a decline to a moderately disturbed condition was apparent 7 wk after restocking and species richness had declined. No such changes occurred under a cage which contained fish continuously over the same period.
Article
A rapid method for measuring the redox potential (Eh) values of marine sediments is described. This method has been used to relate changes in the areas of highly reduced sediment in a sea loch system to the continuously fluctuating inputs of organic waste from a pulp and paper mill. Subsequent faunal changes in these areas can be related to changes in the measured sedimentary redox level. The method is suggested as a rapid means of assessing the potential impact of an additional organic input to a marine sediment.
Article
The rates of sedimentation of organic detritus were measured at 3 stations in two Scottish sea lochs, Loch Etive and Loch Creran, using sedimentation jars exposed at various depths. Details are given of the seasonal and depth distribution of sedimenting material, and its composition for a 1-year period. Differences in the pattern of sedimenting material collected at different depths and in the seasonal patterns of sedimentation at the different stations suggested that, in each case there were differences in the relative importance of detritus from various sources. At all stations, phytoplankton production made a relatively small contribution to the total detritus collected, either directly as dead cells, or indirectly as the faeces of zooplankton organisms. Near the head of Loch Etive there were contributions by filamentous algae and Enteromorpha sp., but a major source of detritus was terrestrial debris, mainly carried into the loch in the waters of the River Etive. In the lower basin of Loch Etive, terrestrial detritus also contributed to the total sedimenting near the surface, but at greater depths much of the material collected in the sedimentation jars probably resulted from short-term resuspension and re-deposition of bottom material, reflecting a net transport of fine sediment from the shallower to the deeper areas of the loch. Secondarily resuspended material was also a major source of material collected in the jars exposed in Loch Creran.
Article
Within a few months of the establishment of a sea cage salmon farm in the Marlborough Sounds, New Zealand, sediment physical and chemical characteristics reflected the extremely high sedimentation rate immediately underneath the fish cages. In the surface sediment, dry weight was reduced to about one-third, density was halved and the volatile solids content increased about seven-fold compared with nearby sediments. Similarly, the sediment pools of ammonium, organic N and total phosphorus were much higher underneath the cages than at farther removed sites. The total ratios were the same (1.5) in the surface sediment underneath the cages and in the feed but markedly higher in the less affected areas. In situ nitrification and denitrification were not measurable in the immediate vicinity of the salmon farm. The potentials for nitrification and denitrification gradually increased from virtually nil underneath the