Article

Horse mussel reef ecosystem services: evidence for a whelk nursery habitat supporting a shellfishery

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

Demonstrating the benefits that marine ecosystems provide to society can support marine spatial planning and enhance the protection of fragile, biodiverse habitats. However, the importance of ecosystem services provided by such habitats is rarely accounted for in spatial management due to a lack of detailed information. The present study investigated the ‘habitat provision’ ecosystem service delivered by horse mussel (Modiolus modiolus (L.)) reefs, a ‘Priority Marine Habitat’ in the NE Atlantic. By working with local fishers, the abundance and demographics of commercially important whelks (Buccinum undatum) were examined. B. undatum catches were three times higher on reef sites and a greater number of smaller individuals were caught on the reefs compared to off-reef habitats. We therefore show that these productive and physically complex mussel reefs are important feeding and nursery areas for whelks, demonstrating the ‘essential fish habitat’ value of the now rare M. modiolus reefs. The results are discussed in the context of marine spatial planning and the potential for historically more widespread shellfish habitats to have been capable of providing substantial ecosystem services.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Quantification requires large amounts of consistently collected data, collected often in unforgiving environments and in collaboration with local fishers. In this Issue, we present a study by Kent et al. (2016) that has done such an elaborate quantification in the North-East Atlantic. Kent et al. (2016) report on a study conducted in horse mussel (Modiolus modiolus (L.)) reefs, a 'Priority Marine Habitat' in the North-East Atlantic. ...
... In this Issue, we present a study by Kent et al. (2016) that has done such an elaborate quantification in the North-East Atlantic. Kent et al. (2016) report on a study conducted in horse mussel (Modiolus modiolus (L.)) reefs, a 'Priority Marine Habitat' in the North-East Atlantic. The researchers worked together with local fishers and examined the abundance and demographics of commercially important whelks (Buccinum undatum). ...
... Both measures are commonly accepted albeit poorly quantified indicators of the nursery habitat ecosystem service (Sheridan & Hays 2003;Van Oudenhoven et al. 2015). In addition, Kent et al. (2016) demonstrate the 'Essential Fish Habitat' (EFH) value of these now rare M. modiolus reefs to decision-makers and fishers. The whelk fishery is of high importance for the Welsh economy, as it is the second-most valuable shellfishery in recent years. ...
Article
In this Editorial to Issue 12–3 (2016) of International Journal of Biodiversity, Ecosystem Services & Management (IJBESM), we introduce this Issue’s articles, which can be of relevance to a wide range of stakeholders, such as local and (inter)national decision-makers, large international firms, farmers, fishery managers and protected area managers. We discuss how various stakeholders could use the findings and, if applicable, how researchers can optimise dissemination and utilisation of their findings. Finally, we welcome a new Editorial Board member and look ahead at the publication of a Special Issue that will address the use of ecosystem services in planning at different scales.
... rainforests, saltmarshes, and aquatic biogenic reefs, are under threat from anthropogenic disturbances (Ellison et al. 2005;Airoldi et al. 2008;Silliman et al. 2009;Newbold et al. 2014;Firth et al. 2015). Biogenic reefs formed by bivalves play an essential role as ecosystem engineers by: (i) promoting higher levels of biodiversity than surrounding local environments (Gutierrez et al. 2003;O'Connor and Crowe 2007); (ii) providing habitat that acts as a nursery for commercially important species (Kent et al. 2016(Kent et al. , 2017; (iii) stabilising sediments (Meadows et al. 1998); (iv) acting as natural wave barriers and protecting soft coastal habitat ; and (v) contributing substantially to nutrient cycling (Kellogg et al. 2013). The loss of such biogenic habitat following disturbance events can lead to changes in many biotic interactions, which can impede the recovery of a system following further disturbances (Lotze et al. 2006;Bertness et al. 2015;Mrowicki et al. 2016). ...
... Clumped mussel habitat can also be beneficial for smaller predators which may hide therein (Thiel and Dernedde 1994), highlighting the importance of considering the ontogenetic and behavioural responses of predators (Pirtle et al. 2012). It is known, for example, that mussel reefs are nursery grounds for whelks (Kent et al. 2016) and crabs (Lindsey et al. 2006) and the size of small predators used in this experiment may spend more time sheltering from larger predators in refuge space afforded by a reef than actively feeding. This should be tested empirically. ...
Article
Full-text available
Spatially complex habitats provide refuge for prey and mediate many predator–prey interactions. Increasing anthropogenic pressures are eroding such habitats, reducing their complexity and potentially altering ecosystem stability on a global scale. Yet, we have only a rudimentary understanding of how structurally complex habitats create ecological refuges for most ecosystems. Better informed management decisions require an understanding of the mechanisms underpinning the provision of physical refuge and this may be linked to prey size, predator size and predator identity in priority habitats. We tested each of these factors empirically in a model biogenic reef system. Specifically, we tested whether mortality rates of blue mussels (Mytilus edulis) of different sizes differed among: (i) different forms of reef structural distribution (represented as ‘clumped’, ‘patchy’ and ‘sparse’); (ii) predator species identity (shore crab, Carcinus maenas and starfish, Asterias rubens); and (iii) predator size. The survival rate of small mussels was greatest in the clumped experimental habitat and larger predators generally consumed more prey regardless of the structural organisation of treatment. Small mussels were protected from larger A. rubens but not from larger C. maenas in the clumped habitats. The distribution pattern of structural objects, therefore, may be considered a useful proxy for reef complexity when assessing predator–prey interactions, and optimal organisations should be considered based on both prey and predator sizes. These findings are essential to understand ecological processes underpinning predation rates in structurally complex habitats and to inform future restoration and ecological engineering practices.
... Horse mussels (Modiolus modiolus) can occur in dense aggregations forming 'biogenic reefs' or 'beds', which support a diverse range of associated species (Fariñas-Franco et al., 2014;Rees et al., 2008). M. modiolus are known to filter large volumes of water (Navarro and Thompson, 1996) and reefs provide a spatial refuge for many other invertebrates (Witman, 1985;Kent et al., 2016), making them ecologically important. Filter feeders act as a natural top-down control on phytoplankton concentrations (Newell, 2007), indeed, oyster reef restoration has been used as an attempt to improve water quality and reduce eutrophication (Coen et al., 2007). ...
... Furthermore, enhanced deposition of organic material by M. modiolus may provide food for associated infauna and more widely enhance fish and bird populations, as has been shown for oyster reefs (van der Zee et al., 2012;Yeager and Layman, 2011). Evidence shows that M. modiolus reefs enhance the abundance of commercially important shellfish (Kent et al., 2016); however the influence of M. modiolus reefs on the wider foodweb has not yet been demonstrated. ...
Article
Horse mussel (Modiolus modiolus) shellfish reefs are a threatened and declining habitat in the North East Atlantic and support high levels of biodiversity. Shellfish can influence the surrounding water column and modify the quality of material that reaches the seabed by filtering water, actively depositing particles and changing the benthic boundary layer due to surface roughness. In the present study M. modiolus biodeposition was measured in a field location for the first time. The results show that M. modiolus enhance sedimentation and contribute to the downward flux of material to the seabed. Approximately 30% of the total sediment deposition was attributed to active filter feeding and overall, the presence of horse mussels enhanced deposition two fold. The results are discussed in terms of the potential for horse mussel reefs to provide ecosystem services to society, through functions such as benthopelagic coupling and sediment stabilisation. Highlighting the societal benefits supplied by marine habitats can help prioritise conservation efforts and feed into the sustainable management of coastal water bodies.
... fisheries) and biodiversity maintenance (Galparsoro, Borja, & Uyarra, 2014). They are particularly important in the cycling and sequestration of carbon and the regeneration of nutrients (Beaumont et al., 2007;Birchenough, Parker, McManus, & Barry, 2012;Kent, Gray, Last, & Sanderson, 2016;Snelgrove et al., 2018), secondary production (Renaud, Morata, Ambrose, Bowie, & Chiuchiolo, 2007), and the mediation of organic enrichment (Beaumont et al., 2007;Snelgrove et al., 2018). Also, benthic marine species offer a rich source of structurally novel and biologically active metabolites for medicinal use (Abou-Elela, Abd-Elnaby, Ibrahim, & Okbah, 2009;Shakeel et al., 2018). ...
... One-way analysis of similarities (ANOSIM) comparing the criteria scores in the implementation phase with 'ecoregion' as the grouping factor success of an MPA, considering that the benthos provides important ecological roles, such as food provision, shelter, and nursery areas for many protected fish, birds, and mammals (Bonsdorff & Blomqvist, 1993;Buhl-Mortensen et al., 2010;Galparsoro et al., 2014;Kent et al., 2016). Although the authors appreciate that including the benthos is not practical for some MPAs (e.g. ...
Article
Full-text available
1 There is concern across the International Council for the Exploration of the Sea (ICES) region that a consideration of vulnerable components and the wider support mechanisms underpinning benthic marine ecosystems may be lacking from the process of marine protected area (MPA) designation, management and monitoring. 2 In this study, MPAs across six European ecoregions were assessed from a benthic ecology perspective. The study included 102 MPAs, designated by 10 countries, and focused on three aspects regarding the role of the benthos in: (i) the designation of MPAs; (ii) the management measures used in MPAs; and (iii) the monitoring and assessment of MPAs. 3 Qualitative entries to a questionnaire based on an existing framework (EU project ‘Monitoring Evaluation of Spatially Managed Areas’, (MESMA) were collected by 19 benthic experts of the ICES Benthic Ecology Working Group. A pedigree matrix was used to apply a numerical scale (score) to these entries. 4 The results showed clear differences in scores between ecoregions and between criteria. The designation-phase criteria generally achieved higher scores than the implementation-phase criteria. Poor designation-phase scores were generally reiterated in the implementation-phase scores, such as scores for assessment and monitoring. 5 Over 70% of the MPA case studies were found to consider the benthos to some extent during selection and designation; however, this was not followed up with appropriate management measures and good practice during the implementation phase. 6 Poor spatial and temporal coverage of monitoring and ineffective indicators is unlikely to pick up changes caused by management measures in the MPA. There is concern that without adequate monitoring and adaptive management frameworks, the MPAs will be compromised. Also, there could be an increased likelihood that, with regard to the benthos, they will fail to meet their conservation objectives. 7 This assessment was successful in highlighting issues related to the representation and protection of the benthos in MPAs and where changes need to be made, such as expanding the characterization and monitoring of benthic species or habitats of interest. These issues could be attributable to an ongoing process and/or an indication that some MPAs only have ‘paper protection’.
... Modiolus modiolus (horse mussel) reefs are structurally complex habitats, characterised by high species diversity (Hirst et al., 2012;Rees et al., 2008;Sanderson et al., 2008). The societal benefits of horse mussel reefs for fishermen have been demonstrated in the Irish Sea (Kent et al., 2016); yet the widespread utilisation of horse mussel reefs as a resource for benthic consumers has not been addressed. ...
... Divers on the UVC transects were able to look around objects and check if shellfish were live or dead, which was not possible on the DDV transects. In a parallel study, comparatively high catch rates of B. undatum on M. modiolus reefs off Pen Llŷn using baited traps (Kent et al., 2016) corroborates the view that DDV is likely to under-record this species. ...
Article
Horse mussel reefs (Modiolus modiolus) are biodiversity hotspots afforded protection by Marine Protected Areas (MPAs) in the NE Atlantic. In this study, horse mussel reefs, cobble habitats and sandy habitats were assessed using underwater visual census and drop-down video techniques in three UK regions. Megafauna were enumerated, differences in community composition and individual species abundances were analysed. Samples of conspicuous megafauna were also collected from horse mussel reefs in Orkney for stable isotope analysis.
... faeces and pseudofaeces (Kent et al., 2017a;Navarro and Thompson, 1997). Modiolus modiolus beds also play an important role in the functioning of marine ecosystems and the provision of ecosystem services (Kent et al., 2017b(Kent et al., , 2016 and are thus regarded as habitats of great conservation importance on a European and International level OSPAR Commission, 2008). ...
... The scallops A. opercularis and C. varia, also characteristic of the habitat, were either absent or present in much lower abundances in 2010 compared with historical observations (see representative photographs in Appendix A). The declines in the whelk B. undatum and decapods (mirroring the findings of Strain et al., 2012), along with the disappearance of queen scallops from areas closed-off to mobile gears, strongly suggest M. modiolus beds are essential habitat for a number of commercially important species, as demonstrated by Kent et al. (2016) for a whelk fishery in Wales (UK). ...
Article
The horse mussel Modiolus modiolus (L.) is a large marine bivalve that aggregates to create complex habitats of high biodiversity. As a keystone species, M. modiolus is of great importance for the functioning of marine benthic ecosystems, forming biogenic habitats used to designate Marine Protected Areas (MPAs). The present study investigates the condition of M. modiolus beds historically subjected to intense scallop fishing using mobile fishing gears. The study, conducted seven years after the introduction of legislation banning all forms of fishing, aimed to establish whether natural habitat recovery occurs after protection measures are put in place. Lower biodiversity and up to 80% decline in densities of M. modiolus were recorded across the current distributional range of the species in Strangford Lough, Northern Ireland. The decline in biodiversity in most areas surveyed was consistent with that observed in biogenic reefs impacted by mobile fishing gears elsewhere. Epifauna, including sponges, hydroids and tunicates, experienced the most substantial decline in biodiversity, with up to 64% fewer taxa recorded in 2010 compared with 2003. Higher variability in community composition and a shift towards faunal assemblages dominated by opportunistic infaunal species typical of softer substrata were also detected. Based on these observations we suggest that, for biogenic habitats, the designation of MPAs and the introduction of fishing bans alone may not be sufficient to reverse or halt the negative effects caused by past anthropogenic impacts. Direct intervention, including habitat restoration based on translocation of native keystone species, should be considered as part of management strategies for MPAs which host similar biogenic reef habitats where condition and natural recovery have been compromised.
... faeces and pseudofaeces (Kent et al., 2017a;Navarro and Thompson, 1997). Modiolus modiolus beds also play an important role in the functioning of marine ecosystems and the provision of ecosystem services (Kent et al., 2017b(Kent et al., , 2016 and are thus regarded as habitats of great conservation importance on a European and International level OSPAR Commission, 2008). ...
... The scallops A. opercularis and C. varia, also characteristic of the habitat, were either absent or present in much lower abundances in 2010 compared with historical observations (see representative photographs in Appendix A). The declines in the whelk B. undatum and decapods (mirroring the findings of Strain et al., 2012), along with the disappearance of queen scallops from areas closed-off to mobile gears, strongly suggest M. modiolus beds are essential habitat for a number of commercially important species, as demonstrated by Kent et al. (2016) for a whelk fishery in Wales (UK). ...
Preprint
The horse mussel Modiolus modiolus (L.) is a large marine bivalve that aggregates to create complex habitats of high biodiversity. As a keystone species, M. modiolus is of great importance for the functioning of marine benthic ecosystems, forming biogenic habitats used to designate Marine Protected Areas (MPAs). The present study investigates the condition of M. modiolus beds historically subjected to intense scallop fishing using mobile fishing gears. The study, conducted seven years after the introduction of legislation banning all forms of fishing, aimed to establish whether natural habitat recovery occurs after protection measures are put in place. Lower biodiversity and up to 80% decline in densities of M. modiolus were recorded across the current dis- tributional range of the species in Strangford Lough, Northern Ireland. The decline in biodiversity in most areas surveyed was consistent with that observed in biogenic reefs impacted by mobile fishing gears elsewhere. Epifauna, including sponges, hydroids and tunicates, experienced the most substantial decline in biodiversity, with up to 64% fewer taxa recorded in 2010 compared with 2003. Higher variability in community composition and a shift towards faunal assemblages dominated by opportunistic infaunal species typical of softer substrata were also detected. Based on these observations we suggest that, for biogenic habitats, the designation of MPAs and the introduction of fishing bans alone may not be sufficient to reverse or halt the negative effects caused by past anthropogenic impacts. Direct intervention, including habitat restoration based on translocation of native keystone species, should be considered as part of management strategies for MPAs which host similar biogenic reef habitats where condition and natural recovery have been compromised.
... They also provide structurally complex habitats that can support dense and diverse communities (Rees et al., 2008;Sanderson et al., 2008). Biogenic reefs are a refuge for juveniles of fish species such as cod, saithe and pollock (Kamenos et al., 2004) and provide settlement habitat for shellfish species including king scallop spat (Kent et al., 2016). The importance of biogenic reefs and their high vulnerability to bottom-towed fishing gears (Cook et al., 2013) is an important consideration for spatial management. ...
Article
The biomass and composition of bycatch from king scallop dredge fisheries was assessed and compared between the English Channel, Cardigan Bay in Wales and around the Isle of Man. Bycatch composition varied significantly at localised, and broad, geographic scales. The mean proportion of scallop dredge bycatch biomass in the English Channel was 19% of total catch biomass. The proportion of bycatch was lower in Cardigan Bay (15%) but notably higher around the Isle of Man (53%). The proportion of individual bycatch species in dredge catches were low, therefore scallop dredging is unlikely to cause a substantial increase the population mortality of individual commercially fished species beyond that caused by the target fisheries for those species, or bycatches of other fisheries. The amount and mortality of organisms left on the seabed in the dredge path was not quantified in this study but should also be considered in management of the fishery. The discard rate of finfish and shellfish of commercial value from the king scallop dredge fishery in the English Channel was between 18 and 100%, with a higher rate of discarding occurring in the eastern English Channel compared to the west. The clear regional differences in bycatch composition and variation in the quantity of discards mean that an area by area approach to managing bycatch species is required in relation to the king scallop dredge fishery.
... The systematic reintroduction of O. edulis throughout its former distributional range in the European Atlantic Marine Protected Area network is a concept that would require a shift in conservation baselines and could re-instate beneficial ecosystem services (see Coen et al., 2007;Kent et al., 2016). Existing data (Appendix A Table A.3) suggest that present day environmental conditions in the Dornoch Firth are generally suitable for restoration: high water quality, adequate substratum and hydrodynamic conditions and the potential for the site to be a sink for larvae. ...
Article
Full-text available
Anthropogenic pressures on the marine environment have escalated and shellfish habitats have declined substantially around the world. Recently, Marine Protected Areas (MPAs) have rapidly increased in number, but management baselines rarely account for historical conditions. Marine examples of habitat restoration are therefore unusual. An interdisciplinary review of management baselines was undertaken for the Dornoch Firth protected area (NE Scotland) as well as three adjacent inlets and 50 km of open coastline. The protected area has low levels of industrial development, is sparsely populated, and previously achieved management objectives. Here we systematically searched for historical evidence of native oyster (Ostrea edulis) beds, a habitat now rare and of conservation importance throughout Atlantic Europe. Archaeological records, navigational charts, historical maps, museum collections, land-use records, fisheries records, public online databases and naturalists' records were searched. We conducted intertidal and subtidal surveys and sample oyster shells were radiocarbon dated. The combined interdisciplinary sources showed that O. edulis occurred in the inlets and open coast areas of NE Scotland, and specifically in the protected area: Probably since the end of the last glaciation to the late 1800s when they were likely over-fished. Present environmental conditions are also suitable for oyster restoration. Habitat restoration in protected areas is an emerging global theme. However, European oyster restoration effort is currently confined to remnant populations with a clear history of exploitation or dwindling associated fisheries. An interdisciplinary review of baselines will probably show scope for the restoration of O. edulis, for nature conservation, in many other European MPAs.
... WFD Shellfish Water Protected Area Compliance 2008-2016 (First reported in 2014 SourceEA (2018) 17 In 2014 the Shellfish Waters Directive (SWD) was subsumed into the Water Framework Directive WFD). For SWD, the parameter was faecal coliforms so the EA used to analyse additional shellfish samples annually to measure compliance. ...
Article
Full-text available
A number of EU and UK regulatory drivers are important for improving the condition of the marine environment. These include the EU Marine Strategy Framework Directive (MSFD), the EU Water Framework Directive (WFD), the EU Habitats and Birds Directives and overarching vision statements such as the UK Marine Policy Statement and English legislation including the Inshore Fisheries and Conservation Authority (IFCA) byelaws and the South Marine Plan. The UK Government aims to have clean, healthy, safe, productive and biologically diverse oceans and seas.i It is within this context that this research is situated, aiming to describe and value the socio-economic and environmental benefits of improving water quality (e.g. by reducing the amount of faecal contamination) in terms of shellfish waters in the Solent using an ecosystem services framework to model changes in terms of shellfish provisioning services valued in terms of Gross Output and Indirect Output. Ecosystem services have been described as ‘the direct and indirect contributions of ecosystems to human wellbeing’ and need to be incorporated into management frameworks and strategies as otherwise their degradation is not taken into accountii. This research contributes to the promotion of the wider value of UK shellfish waters, building on previous work in Chichester Harbour (delivered in January 2018) and now expanded using five priority shellfish waters in the Solent as case studies. The Solent comprises a large coastal water body around 20 miles long, separating the Isle of Wight from mainland England, which is fed by several estuaries and harbours. By presenting a narrative of the wider value and ecosystem services provided by shellfish beds, and modelling the benefits of water quality improvements for the provisioning services of shellfish beds, it is possible to demonstrate that it is worth investing in better water quality and shellfish productivity to obtain wide societal benefits. The five priority waters considered for this study are:  Portsmouth harbour  Langstone harbour  Southampton water  Approaches to Southampton Water  Central Solent (‘Hillhead’) The four priority shellfish species considered for this study are:  Manilla clams (Venerupis philippinarum syn. Ruditapes phlippinarum)  Hard-shell clams (Mercenaria mercenaria)  Cockles (Cerastoderma edule)  Native oyster (Ostrea edulis) Due to the growing recognition of the ecosystem services provided by suspension-feeding bivalves (such as clams, cockles and oysters), estuarine restoration projects supporting natural remediation (water clarity improvements, reduction of nutrient loading / eutrophication, filtration, buffering against algal blooms) can notably improve water quality and enhance resilience of estuarine ecosystems. Due to their wide tolerance of turbidity, oysters may represent the most desirable type of bivalve for restoration of estuarine ecosystems but in this instance, the main fisheries by volume are for the two species of clams listed above and cockles. Southern IFCA are also delivery partners for an oyster restoration project in the Solent, which while not modelled, demonstrates both the negative impacts of the decline of oysters as well the need, and potential, for restoration.v The objective is to reseed five million juvenile oysters in sanctuary sites and to date 23,000 brood oysters have been stocked beneath marina pontoons.vi Improving the evidence base regarding the value of shellfish is of crucial importance to marine and coastal regulators such as the Environment Agency (EA) and Inshore Fisheries and Conservation Authorities (IFCAs). The evidence and model provided in this report can be integrated providing a supporting tool for cost-benefit analysis (CBA) when considering possible regulatory and policy interventions, as well as making the case for investment in natural systems.
... Quantitative data on the degree to which fish and macroinvertebrates are enhanced by bivalve habitats are rare outside of the United States. While there has been recent progress in understanding the role of Modiolus modiolus in Europe as an important habitat for the commercially important whelk Buccinum undatum (Kent et al. 2016(Kent et al. , 2017, for most bivalve habitats outside of the U.S. evidence is limited to historical documentation of species counts (e.g. Moebius 1883; Riesen and Reise 1982). ...
Chapter
Several bivalve families include species that occur in sufficient densities to modify the environment and create structured biogenic habitat. These habitats have also suffered among the highest losses of any marine habitat globally. In the case of bivalve reefs, the physical structure provided by the shells, supplied with biodeposits produced from filter feeding, supports a high density of macroinvertebrate prey, as well as providing shelter for many juvenile fish. This combination leads to enhanced fish production when compared to the unstructured sediment; the habitat type which typically replaces bivalve reefs when they are destroyed. Measuring the densities of juvenile fish and crustaceans on oyster reefs, and at unstructured control sites provides a measure of the net increase in juvenile fish and large crustaceans supported by oyster habitat. Applying growth and mortality schedules from fishery stock assessment literature allows an estimate of the increased lifetime production of juveniles by oyster reef habitats. Species may also benefit from oyster reefs at later life history stages, but these potential benefits have not been included in the current estimates of production. Services such as increased fish production have been used to highlight the range of stakeholders, in addition to the oyster fishers, that benefit from oyster habitat. The broader constituent base for bivalve habitats includes groups such as recreational anglers and commercial fishers as well as the industries that support them. Engaging with these stakeholders through quantifying the benefits of bivalve habitats to fisheries has proven an invaluable asset in promoting bivalve habitat restoration globally, as well as in drawing more funding into restoration efforts. Furthermore, quantifying fish production introduces the potential to include habitats such as those produced by bivalves in Ecosystem-based Fisheries Management.
... In line with the current United Nations 'Decade on Ecosystem Restoration' (UN, 2020), O. edulis restoration is ongoing or planned in several countries across Europe (Pogoda et al., 2019. These projects aim to recover the important functional role which bivalve shellfish, as ecosystem engineers and filter-feeders, played in coastal environments (Coen et al., 2007;Kent et al., 2016Kent et al., , 2017bKent et al., , 2017aMcAfee and Bishop, 2019;Lee et al., 2020;zu Ermgassen et al., 2020b). ...
Article
European oyster (Ostrea edulis) restoration often requires the timely deployment of shell habitat for larval settlement. To inform this increasingly popular process, the present study investigated temporal and spatial abundance patterns of O. edulis larvae in a rare commercial fishery (Loch Ryan, Scotland, UK). Patterns in larval abundance were analysed against variability in temperature, salinity, chlorophyll, oxygen, tidal/moon phase, light, date, and location. ‘Temperature sum’ (sum total of degrees per day above 7 °C) was the most significant seasonal predictor of larval abundance; with a peak at 617 degree-days. Oyster larval abundance did not significantly vary between oyster bed and non-bed habitats but was significantly higher in the mid and near-surface part of the water column. The findings are discussed in the context of emerging international restoration initiatives and have implications for: where habitat restoration would be successful; the prediction of larval connectivity between sites; and a transferable indicator to optimise shell-habitat deployment timing.
... The European native oyster Ostrea edulis (Linnaeus, 1758) once formed extensive beds along Europe's coastline that constituted a highly significant resource for coastal populations and were probably a dominant ecological component (Thurstan et al., 2013;Gercken and Schmidt, 2014;Kent et al., 2016;Fariñas-Franco et al., 2018). Shellfish, such as oysters, can be keystone species that provide habitat, refuge and foraging ground for many invertebrates and vertebrates, some with commercial value, while their filter-feeding behaviour contributes to benthopelagic coupling (Coen et al., 2007;Kent et al., 2017a;Kent et al., 2017b). ...
Article
Full-text available
The European oyster Ostrea edulis is a keystone species that is internationally recognised as 'threatened and declining' in the NE Atlantic by OSPAR and several nations have consequently adopted strategies for its conservation and restoration. Understanding the settlement behaviour of O. edulis larvae is crucial to inform these strategies. We compared the efficiency of several treatments in triggering settlement. The most effective settlement occurred with the presence of conspecifics: 100% settled in < 23 h. Marine stones with habitat-associated biofilms induced 81% settlement that started after a 45 h delay. Sterile shells and terrestrial stones did not induce more settlement than control treatments. These results indicate that O. edulis larvae are gregarious and finely-tuned to settle in response to cues which are indicative of their adult habitat requirements. The role of chemical cues in mediating settlement, and the importance of this to restoration, are discussed.
... In line with the current United Nations 'Decade on Ecosystem Restoration' (UN, 2020), O. edulis restoration is ongoing or planned in several countries across Europe (Pogoda et al., 2019. These projects aim to recover the important functional role which bivalve shellfish, as ecosystem engineers and filter-feeders, played in coastal environments (Coen et al., 2007;Kent et al., 2016Kent et al., , 2017bKent et al., , 2017aMcAfee and Bishop, 2019;Lee et al., 2020;zu Ermgassen et al., 2020b). ...
Poster
Full-text available
The Dornoch Environmental Enhancement Project (DEEP) seeks to restore native European oysters (Ostrea edulis) to the Dornoch Firth and requires four million oysters to achieve its goal. The entire annual UK aquaculture supply of native oysters is, at present, incapable of delivering this requirement. This project works with the Loch Ryan Oyster Fishery Co. Ltd (LROFC) to improve the supply of oysters from the last remaining native oyster fishery in Scotland. Operating sustainably since 1701, LROFC is an oyster fishery of scale but is operating at a historically low-level. Therefore, there is scope to enhance the fishery in Loch Ryan and learn how restored oyster beds might function. Oyster populations can be increased by enhancing available habitat with old shell ‘cultch’, providing suitable substratum for larval attachment (Abbe, 1988; Korringa, 1946; Mackenzie, 1970). Knowledge of the timing of oyster larvae in the plankton and their settlement needs are required to optimise cultch deployment: when, where, and what shell cultch should be put in the water? This project investigates the distribution of bivalve larvae in the water column (surface, mid, bottom) during weekly sampling from June to September 2019, as well as contrasting spring and neap tides. The purpose of the study was to inform the deployment of shell cultch for habitat enhancement in Loch Ryan but also restoration work in the Dornoch Firth. Larvae were filtered from 200 L water samples at eight sites, subsamples enumerated, and larval sizes measured. A total of 55,000 L of water was filter from Loch Ryan. Preliminary analyses of spatial and temporal variation in bivalve larval numbers are explored. Seasonal increases in numbers were seen during July and August. Greater numbers of bivalve larvae were observed in surface and mid-water samples, compared to bottom samples. Further analyses will more closely investigate multifactorial drivers such as location, depth, tidal state, moon phase, and water temperature, as well as genetic analyses to confirm the presence of native oysters.
... To assess effects of position within patches on the size distribution of mussels, a multivariate analysis was performed. This procedure is used commonly for grain size distribution analyses (Cosser 1989;Seiderer and Newell 1999) and has been previously applied to whelk populations (Kent et al. 2016). Mussel size structure and assemblage structure of both resident and recruited fauna were analysed initially for overdispersion (function betadisper in package vegan) to ensure consistency with the assumptions of multivariate analysis (Anderson 2006;Anderson and Walsh 2013). ...
Article
Reef-forming species play a key role creating, modifying and maintaining important habitat and their associated communities. Globally, many of these habitats are extensively fragmented but our understanding of key ecological processes is drawn from older studies performed in less degraded environments with extensive reef habitats. We tested whether proximity to habitat edges affected the persistence and functioning of fragmented intertidal mussel reefs, Mytilus edulis, at three sites in sedimentary habitats in Northern Ireland. Specifically, we quantified and compared key ecological properties in mid-habitat and edges and hypothesised that at the edges, there would be (i) larger individual mussels, (ii) lower recruitment, (iii) lower associated taxon diversity, (iv) lower biodeposition, (v) greater predation intensity and (vi) greater food availability. Additionally, we tested whether rates of functioning (e.g. organic matter accumulation) were greater in mussel patches (edge and mid-habitat) compared to sediment without mussels (vii). We did find larger mussels at the edges of patches, where there was also less organic enrichment of the sediment compared to mid-habitat (but more than areas without mussels). None of the other variables quanitifed differed consistently between the edge and mid-habitat. The lack of strong edge effects identified may be explained by the nature of the mussel habitat in this study, i.e. intrinsically greater proportion of edges compared to more extensive reefs. Our results suggest that at the scale of the reef patches in this study, edge effects were not as strong as previously thought in terms of regulating key ecological processes.
... Though there is substantial evidence that bivalve habitats often support a greater abundance of associated species than nearby unstructured habitats (Supporting Information Table S2), the contribution of this to the provision of other fisheries species was quantified in only one case study. M. modiolus beds were found to have three times higher densities of whelk, Buccinum undatum, 20 times higher densities of queen scallop, Aequipecten opercularis, and four times higher densities of spider crab, Maja brachydactyla, than on nonmussel sites Kent, Gray, Last, & Sanderson, 2016). ...
Article
Full-text available
• Bivalve habitat restoration is growing in geographic extent and scale globally. While addressing the wide‐scale loss of these biogenic habitats is still a key motivation behind restoration efforts, stakeholders and funders are increasingly drawn to shellfish restoration for the many ecosystem services these habitats provide. • There is clear evidence for the provision of ecosystem services from species targeted for restoration in the USA, in particular Crassostrea virginica. Ecosystem services, however, remain largely unquantified or even undescribed for the majority of other species targeted for restoration. • A structured review of the literature was undertaken and supplemented by expert knowledge to identify which ecosystem services are documented in the following other bivalve species targeted for restoration: Ostrea edulis, Ostrea angasi, Crassostrea rhizophorae, Perna canaliculus, Modiolus modiolus, Mytilus edulis, Mytilus platensis, Crassostrea gigas, Ostrea denselamellosa, Crassostrea ariakensis, and Crassostrea sikamea. • Key knowledge gaps in quantifying ecosystem services and the ecosystem engineering properties of habitat‐building bivalves contributing to the provision of ecosystem services were identified. Ecosystem services with the potential to be widely applicable across bivalve habitat‐building species were identified. • Though there is evidence that many of the ecosystem engineering properties that underpin the provision of ecosystem services are universal, the degree to which services are provided will vary between locations and species. Species‐specific, in situ, studies are needed in order to avoid the inappropriate transfer of the ecosystem service delivery between locations, and to further build support and understanding for these emerging targets of restoration.
... In all cases catch composition was far larger than existing MLS, with management box E9 being the exception, with large numbers of individuals recorded <45mm TSL. Reasons behind this is attributed to the presence of a horse mussel reef, with this habitat known as being a key nursery ground for juvenile whelks (Kent et al., 2016). Recruitment cohorts are visible through discernible peaks in most size frequencies, presenting the opportunity to monitor future recruitment. ...
Technical Report
Full-text available
The whelk project is a collaboration between Orkney Sustainable Fisheries Ltd (OSF) and the fishing industry. OSF hopes to provide information that enables both fishery managers and members of the fishing industry to better safeguard the future of the whelk fishery in Orkney. To ensure sustainability and survivability of the local sector fishers' and fishery managers robust science is required to inform the potential for regionally based management plans. A project was implemented from 2018 to 2020 to collect regional specific biological information the common whelk (Buccinum undatam) fishery around Orkney. This was achieved by conducting on board observer trips to collect biological information on catch composition of both landed and discarded components of the catch whilst also gather anecdotal information on the historical and current extent of the fishery. During these observer trips a total of 13,151 whelks were sampled with stratified subsamples also collected from 7 non statutory management boxes around Orkney from which functional maturity and statolioth ageing was estimated. Stratified biological samples were dissected and the internal gonads of 2,193 individuals were assessed against an established maturity criterion developed by the Centre for Environment Fisheries and Aquaculture Science (CEFAS). Functional maturity varied over small spatial scales with L50 ranging from 80.9-97.2 mm TSL. Clear distinction was made between smaller L50 estimates of historically exploited stocks compared to larger L50 from virgin grounds. Current exploitation in relation to estimates of L50 were also examined by calculating the percentage of catch below L50 per management box. Percentage of catch less than L50 ranged from 4-39%. Overall functional maturity estimates compared to the size frequency distribution of landed catch demonstrates that the fishery is currently removing larger numbers of individuals prior to spawning, exposing populations to long term recruitment failure and capitulates the notion that such fisheries operate under a "Boom and Bust" model.
Technical Report
Full-text available
Climate change and marine conservation • The historical extent of horse mussels has reduced around the UK in recent years. • Horse mussel beds are potentially threatened by several climate change stressors including rising seawater temperatures, ocean acidification, changes in wave exposure and ocean currents. • A predictive habitat modelling study suggests that horse mussel beds may lose all of their most suitable habitat within UK waters by 2080 under a medium emissions climate change scenario. • Horse mussel beds are sensitive to a range of human activities, including use of towed demersal fishing gear, scallop dredging, cable laying and other activities which cause seabed disturbance. • Reducing or removing pressures associated with human activities is likely to be the most effective method of increasing the resilience of horse mussel beds to climate change.
Article
Full-text available
Oyster reef ecosystems used to form significant components of many temperate and subtropical inshore coastal systems but have suffered declines globally, with a concurrent loss of services. The early timing of many of these changes makes it difficult to determine restoration targets which consider interdecadal timeframes, community values and shifted baselines. On the Australian continent, however, the transition from Indigenous (Aboriginal) to Westernized resource use and management occurred relatively recently, allowing us to map social-ecological changes in detail. In this study, we reconstruct the transformations in the Sydney rock oyster (Saccostrea glomerata) wild commercial industry of central and southeast Queensland, and by extension its reef ecosystems, as well as the changing societal and cultural values related to the presence and use of the rock oyster through time. By integrating data from the archaeological, anthropological and fisheries literature, government and media accounts, we explore these transformations over the last two centuries. Before the 1870s, there was a relative equilibrium. Aboriginal peoples featured as sole traders to Europeans, supplying oysters and becoming a substantial component of the industry's labour pool. Effectively, Australia's commercial oyster industry arose from Aboriginal-European trade. During this initial phase, there was still a relative abundance of wild oyster, with subtidal oyster reef structures present in regions where oysters are today absent or scarce. By contrast, these reefs declined by the late 19th century, despite production of oysters increasing due to continued large-scale oyster recruitment and the expansion of oyster cultivation in intertidal areas. Production peaked in 1891, with successive peaks observed in regions further north. During the 1890s, flood events coupled with land-use changes introduced large quantities of silt into the system, which likely facilitated an increase in oyster pests and diseases, ultimately decreasing the carrying capacity of the system. Today oyster production in this region is less than one-tenth of historical peak production. Many cultural heritage components have also been lost. Indigenous management is now very minor due to the massive decimation of Aboriginal populations and their respective practices. Yet, we found strong cultural attachment to midden remains and oyster production continues within Indigenous communities, with considerable broader community support. This study highlights the value of conducting thorough analysis of early media accounts as a means for reconstructing historical resource decline and management. It further demonstrates the application of historical information and context for contemporary management, protection and restoration of much-altered coastal social-ecological systems.
Article
Full-text available
The effective use of ecosystem engineers in biodiversity conservation is contingent on an understanding of those factors that influence the magnitude and direction of their effects. At patch scales, effects of ecosystem engineers on associated communities can range from positive to negative according to how the ecosystem engineer modifies environmental conditions. In a metaanalysis of 68 empirical studies, we assessed how, for a widespread group of ecosystem engineers- the marine habitat-forming bivalves-bivalve taxon, density, habitat, tidal elevation and latitude, as well as habit, or lifestyle, of associated taxa, influences the magnitude and direction of their effect on associated invertebrates. Overall, marine bivalves had a positive effect on both species abundance and species density, but effect sizes varied considerably according to bivalve traits and environmental setting. Oysters enhanced invertebrate abundance to a greater extent than either mussels or pinnids, perhaps because of the greater habitat heterogeneity they provide. Nevertheless, the effect of mussels on associated communities was generally more responsive to spatial variation in engineer traits and environmental context than the effect of oysters or pinnids. Positive effects of mussels on associated species abundance decreased at high mussel densities, were greater at subtidal than mid-low intertidal elevations and differed among faunal habits depending on habitat setting. Knowledge of those conditions under which positive effects of bivalves on associated biodiversity is greatest will help in identifying which species of ecosystem engineer, at which sites, should be prioritised for conservation and restoration, where the goal is enhancement of biodiversity.
Article
Full-text available
Modiolus modiolus (horse mussel) reefs are an example of marine biodiversity hotspots of high conservation importance. Due to historical destruction and slow rates of recovery, the habitat is considered threatened and/or declining under the OSPAR Convention for the Protection of the Marine Environment of the NorthEast Atlantic 1992, and therefore incorporated into the conservation legislation of several countries. An analysis of genetic connectivity and diversity of nine M. modiolus reefs across Scotland, both within and outside of Marine Protected Areas (MPAs), was undertaken using 12 newly developed microsatellite markers. Analyses indicated moderate to high levels of genetic connectivity between all populations and significantly low genetic variance among populations. Generally, a lack of spatial genetic structure was determined though several populations were highlighted as potentially genetically separated. Structure and connectivity results were largely corroborated by network visualization which additionally identified several potentially key populations. All populations showed departure from Hardy-Weinberg Equilibrium (HWE) and positive inbreeding coefficients, suggesting reduced genetic diversity and/or reflecting the high frequency of null alleles observed across populations. However, allelic richness was uniformly high across all reefs compared to previously reported results for the habitat. Results broadly suggest that an open system of M. modiolus populations exists in Scottish waters and align with conclusions from prior larval dispersal modeling. Findings highlight that neither M. modiolus populations nor the MPAs where they are found should be considered discrete, independent entities and support the protection of features within MPAs in concert with non-designated areas and across varying spatial scales. It is proposed that potential for greater protection exists if all relevant Scottish MPAs, i.e., Frontiers in Marine Science | www.frontiersin.org 1 March 2022 | Volume 9 | Article 772259 Mackenzie et al. Horse Mussel Reef Genetics both those where M. modiolus reefs are a designated feature and those that host M. modiolus reefs, had statutory restrictions on all activities that cause damage to the sea bed. Such protection may facilitate the support of vulnerable populations by more resilient populations, particularly under climate change. Furthermore, given that a large number of unprotected M. modiolus populations may be important components in the interdependent system of reef populations, supplementary genetics studies informed by larval dispersal modeling are recommended to identify further key populations for safeguarding.
Article
Full-text available
Recreational users appreciate the UK marine environment for its cultural ecosystem services (CES) and their use and non-use values. UK Governments are currently establishing a network of marine protected areas (MPAs) informed by ecological data and socio-economic evidence. Evidence on CES values is needed, but only limited data have been available. We present a case study from the UK National Ecosystem Assessment (NEA) follow-on phase that elicited divers’ and anglers’ willingness to pay (WTP) for potential MPAs. The case study is an innovative combination of a travel-cost based choice experiment and an attribute-based contingent valuation method. Our study design allowed us to understand the marine users’ preferences from both a user and a stewardship perspective. Following the UK NEA’s place-based CES framework, we characterised marine CES as environmental spaces that might be protected, with features including the underwater seascape, and iconic and non-iconic species. Our survey highlighted the importance of CES to divers and anglers. A wide variety of marine spaces influenced user-WTP, while stewardship-WTP was most influenced by management restrictions, species protection, and attitudes towards marine conservation. An understanding of key stakeholders’ CES values can inform a more holistic and sustainable approach to marine management, especially for decisions involving trade-offs between marine protection and opportunity costs of the blue economy.
Article
Full-text available
Native oyster reefs once dominated many estuaries, ecologically and economically. Centuries of resource extraction exacerbated by coastal degradation have pushed oyster reefs to the brink of functional extinction worldwide. We examined the condition of oyster reefs across 144 bays and 44 ecoregions; our comparisons of past with present abundances indicate that more than 90% of them have been lost in bays (70%) and ecoregions (63%). In many bays, more than 99% of oyster reefs have been lost and are functionally extinct. Overall, we estimate that 85% of oyster reefs have been lost globally. Most of the world's remaining wild capture of native oysters (> 75%) comes from just five ecoregions in North America, yet the condition of reefs in these ecoregions is poor at best, except in the Gulf of Mexico. We identify many cost-effective solutions for conservation, restoration, and the management of fisheries and nonnative species that could reverse these oyster losses and restore reef ecosystem services.
Article
Full-text available
The oyster habitat in the USA is a valuable resource that has suffered significant declines over the past century. While this loss of habitat is well documented, the loss of associated ecosystem services remains poorly quantified. Meanwhile, ecosystem service recovery has become a major impetus for restoration. Here we propose a model for estimating the volume of water filtered by oyster populations under field conditions and make estimates of the contribution of past (c. 1880–1910) and present (c. 2000–2010) oyster populations to improving water quality in 13 US estuaries. We find that filtration capacity of oysters has declined almost universally (12 of the 13 estuaries examined) by a median of 85 %. Whereas historically, oyster populations achieved full estuary filtration (filtering a volume equivalent or larger than the entire estuary volume within the residence time of the water) in six of the eight estuaries in the Gulf of Mexico during summer months, this is now the case for only one estuary: Apalachicola Bay, Florida. By contrast, while all five estuaries on the North Atlantic coast showed large decreases in filtration capacity, none were achieving full estuary filtration at the time of our c. 1900 historic baseline. This apparent difference from the Gulf of Mexico is explained at least in part by our North Atlantic baseline representing a shifted baseline, as surveyed populations were already much reduced by exploitation in this region.
Article
Full-text available
This study describes the impact of the first passage of two types of bottom-towed fishing gear on rare protected shellfish-reefs formed by the horse mussel Modiolus modiolus (L.). One of the study sites was trawled and the other was scallop-dredged. Divers collected HD video imagery of epifauna from quadrats at the two study sites and directed infaunal samples from one site. The total number of epifaunal organisms was significantly reduced following a single pass of a trawl (90%) or scallop dredge (59%), as was the diversity of the associated community and the total number of M. modiolus at the trawled site. At both sites declines in anthozoans, hydrozoans, bivalves, echinoderms and ascidians accounted for most of the change. A year later, no recovery was evident at the trawled site and significantly fewer infaunal taxa (polychaetes, malacostracans, bivalves and ophuroids) were recorded in the trawl track. The severity of the two types of impact reflected the undisturbed status of the habitats compared to previous studies. As a ‘priority habitat’ the nature of the impacts described on M. modiolus communities are important to the development of conservation management policy and indicators of condition in Marine Protected Areas (EU Habitats Directive) as well as indicators of ‘Good Environmental Status’ under the European Union Marine Strategy Framework Directive. Conservation managers are under pressure to support decisions with good quality evidence. Elsewhere, indirect studies have shown declines of M. modiolus biogenic communities in fishing grounds. However, given the protected status of the rare habitat, premeditated demonstration of direct impact is unethical or illegal in Marine Protected Areas. This study therefore provides a unique opportunity to investigate the impact from fishing gear whilst at the same time reflecting on the dilemma of evidence-based conservation management.
Article
Full-text available
We reviewed studies providing quantitative measurements of abundance of fishes and large mobile crustaceans on oyster reefs and on nearby sedimentary habitat in the southeast United States. For each species, we compared density by size (age) class on oyster reefs and sedimentary bottom as a means of estimating the degree to which restoration of oyster reef on sedimentary bottom could augment abundances. By applying published information on growth rates of each species and a combination of empirical data and published information on age-specific survivorship, we calculated the per-unit-area enhancement of production of fishes and large mobile crustaceans expected from the addition of oyster reef habitat. For this calculation, we gave the reef habitat full credit for the expected lifetime production of species whose recruitment was judged to be limited by the area of oyster reefs based on nearly exclusive association of recruits to reefs. For species that were only modestly enhanced in abundance by oyster reefs, we gave the reef credit for the fraction of production that is derived from consumption of reef-associated prey, using a combination of gut content data and natural history information. This combination of analyses and calculations revealed that 10 m(2) Of restored oyster reef in the southeast United States is expected to yield an additional 2.6 kg yr(-1) of production of fish and large mobile crustaceans for the functional lifetime of the reef. Because the reef is biogenic and self-sustaining, the lifetime of a reef protected from bottom-disturbing fishing gear is limited by intense storms or sedimentation. A reef lasting 20 to 30 yr would be expected to augment fish and large mobile crustacean production by a cumulative amount of 38 to 50 kg 10 m(-2), discounted to present-day value. This set of calculations assumes that oyster reef habitat now limits production of reef-associated fish and crustaceans in the southeast United States. This assumption seems reasonable based on the tight associations of so many fishes with reef-dependent prey, and the depletion of reef habitat over the past century.
Article
Full-text available
Age and growth ofBuccinum undatum off Douglas (Isle of Man, U.K.) were studied using four independent methods: length-frequency analyses (LFA), operculum analysis (OA), markrecapture experiment (MRE) and laboratory rearing (LR). Within the 16-month period between February 1989 and June 1990, only the January 1990 sample showed histograms allowing possible age group determination. Among the several length frequency analyses applied to this sample, the growth analysis program MIX calculated thatBuccinum reaches mean lengths of 28.5, 45.8, 59.9, 71.5 and 81.0 mm at the end of its first, second, third, fourth and fifth year, respectively, with an asymptotic length (L∞) of 123.8 mm and Brody growth coefficient (K) of 0.20. Whilst the results from the LFA were supported by those from the OA and the MRE, growth in the laboratory differed; however, this was expected. Both K and L values found in this study are higher than those in two previous studies undertaken forBuccinum in northeastern England and northern France.
Article
Full-text available
Recent surveys of groundwater invertebrates (stygofauna) worldwide are yielding rich troves of biodiversity, with significant implications for invertebrate systematists and phylogeneticists as well as ecologists and groundwater managers. What is the ecological significance of this high biodiversity of invertebrates in some aquifers? How might it influence groundwater ecosystem services such as water purification or bioremediation? In terrestrial ecosystems, bio- diversity is typically positively correlated with rates of ecosystem functions beneficial to humans (e.g. crop pollination). Ho wever, the links between biodiversity, ecosystem function, and ecosystem services in groundwater are unknown. In some aquifers, feeding, movement and excretion by diverse assemblages of stygofauna potentially enhance groundwater ecosystem services such as water purification, bioremediation and water infiltration. Further, as specific taxa apparently play 'keystone' roles in facilitating ecosystem services, declines in abundance or even their extinction have serious repercussions. One way to assess the functional significance of biodiversity is to identify 'ecosystem service providers', characterise their functional relationships, determine how service provision is affected by community structure and environmental variables, and measure the spatio-temporal scales over which these operate. Examples from Australian and New Zealand alluvial aquifers reveal knowledge gaps in understanding the functional importance of most stygofauna, hampering effective protection of currently undervalued groundwater ecosystem services.
Article
Full-text available
The vast majority of published papers concerning seagrass meadows contain statements to the effect that seagrass beds serve as important nurseries for many species. We reviewed more than 200 papers that were relevant to the nursery role hypothesis. We used both vote counting and meta-analytic techniques to evaluate whether the body of previous studies that report seagrass meadows to be nursery grounds actually contain data that support this proposition. We restricted our analyses to papers that compared seagrass beds to other habitats, and examined data on a variety of well-studied species concerning their density, growth, survival and migration to adult habitat. Within this group of papers, we considered potential factors that could influence the nursery function (e.g. location, or laboratory vs field studies). We also evaluated case histories of well-documented large-scale seagrass losses on the nursery function. Major results were consistent with the expectations that abundance, growth and survival were greater in seagrass than in unstructured habitats. Abundance data also suggested that seagrass beds in the Northern Hemisphere might be more important as nursery areas than those in the Southern Hemisphere. Surprisingly, few significant differences existed in abundance, growth or survival when seagrass meadows were compared to other structured habitats, such as oyster or cobble reefs, or macroalgal beds. Nor were there decreases in harvests of commercially important species that could clearly be attributed to significant seagrass declines in 3 well-studied areas. However, there were decreased abundances of juveniles of commercially important species in these areas, suggesting a strong link between seagrass abundance and those of juvenile finfish and shellfish. One important implication of these results is that structure per se, rather than the type of structure, appears to be an important determinant of nursery value. Clearly, more rigorous studies that test all aspects of the nursery role hypothesis are clearly needed for seagrass meadows as well as other structured habitats. The results of such studies will allow better decisions to be made concerning the conservation and restoration of marine habitats.
Article
Full-text available
An experimental artificial reef was constructed in Strangford Lough, Northern Ireland as part of trials to regenerate damaged biogenic reefs formed by the horse mussel Modiolus modiolus. Experimental reef plots were constructed using Pecten maximus shell as cultch. Clumps of live adult M. modiolus were translocated from nearby natural reefs into cultch with a high profile (elevated cultch), cultch with a low profile (flattened cultch), as well as directly into the seafloor. The aim of the study was to test the hypothesis that translocated mussel clumps would increase habitat complexity thus accelerating community succession and enhancing natural recruitment of M. modiolus spat. These effects were predicted to be greater on elevated cultch due to greater protection from predators and increased accessibility to food resources. Within the artificial reef array the translocated clumps had a significant positive effect on recruitment compared to cultch without mussels with average densities of spat settled on the translocated M. modiolus clumps ranging from 100 to 200 individuals m- 2 compared to 4 to 52 spat m- 2 on cultch without mussels. Recruitment of M. modiolus spat was also significantly higher on translocated horse mussels when compared to natural reefs where densities of 8 - 36 spat m- 2 were recorded. Reef elevation appeared to provide some degree of protection from predators but differences in translocated M. modiolus survival on the different elevation treatments were not significant. In total, 223 taxa were recorded 12 months after reef construction. The presence of translocated clumps of M. modiolus was the main driver of the increases in faunal diversity and species abundance. Application of objective criteria to assess the performance of artificial reefs suggested that translocation of M. modiolus clumps alone achieved most of the restoration objectives. Consequently this pilot study demonstrates a straightforward and realistic intervention technique that could be used to kick start the regeneration and expansion of impacted mussel and similar biogenic reefs elsewhere.
Article
Full-text available
People around the world are looking to marine ecosystems to provide additional benefits to society. As they consider expanding current uses and investing in new ones, new management approaches are needed that will sustain the delivery of the diverse benefits that people want and need. An ecosystem services framework provides metrics for assessing the quantity, quality, and value of benefits obtained from different portfolios of uses. Such a framework has been developed for assessments on land, and is now being developed for application to marine ecosystems. Here, we present marine Integrated Valuation of Ecosystem Services and Tradeoffs (InVEST), a new tool to assess (i.e., map, model, and value) multiple services provided by marine ecosystems. It allows one to estimate changes in a suite of services under different management scenarios and to investigate trade-offs among the scenarios, including implications of drivers like climate. We describe key inputs and outputs of each of the component ecosystem service models and present results from an application to the West Coast of Vancouver Island, British Columbia, Canada. The results demonstrate how marine InVEST can be used to help shape the dialogue and inform decision making in a marine spatial planning context.
Article
Full-text available
Michael W. Beck, Kenneth L. Heck, Jr., Kenneth W. Able, Daniel L. Childers, David B. Eggleston, Bronwyn M. Gillanders, Benjamin Halpern, Cynthia G. Hays, Kaho Hoshino, Thomas J. Minello, Robert J. Orth, Peter F. Sheridan and Michael P. Weinstein
Article
Full-text available
The importance of restoring filter-feeders, such as the Eastern oyster Crassostrea virginica, to mitigate the effects of eutrophication (e.g. in Chesapeake Bay) is currently under debate. The argument that bivalve molluscs alone cannot control phytoplankton blooms and reduce hypoxia oversimplifies a more complex issue, namely that ecosystem engineering species make manifold contributions to ecosystem services. Although further discussion and research leading to a more complete understanding is required, oysters and other molluscs (e.g. mussels) in estuarine ecosystems provide services far beyond the mere top-down control of phytoplankton blooms, such as (1) seston filtration, (2) benthic–pelagic coupling, (3) creation of refugia from predation, (4) creation of feeding habitat for juveniles and adults of mobile species, and for sessile stages of species that attach to molluscan shells, and (5) provision of nesting habitat.
Article
Full-text available
The spatial heterogeneity of epifauna on a Modiolus modiolus reef off north-west Wales was investigated using divers. The community associated with these horse mussels was similar to that described previously from Loch Creran and the north basin of Strangford Lough. Some differences in epifauna may be attributable to the less sheltered nature of the site. Modiolus modiolus numbers and the associated epifaunal community were significantly different between ridge and trough sub-habitats. Troughs can be considered ‘reduced’ ridge communities whereas ridges have high densities of horse mussels and certain sessile taxa were correlated with their abundance. Modiolus modiolus aggregation as a competitive response to the feeding environment, enhanced food availability on ridges and sediment deposition amongst mussel clumps may start to explain the undulating bed-form. Patchiness in community composition and periodic cover by ophuroids has implications when considering the monitoring of the horse mussel community. Stratified, in situ recording of the highly populated ridges could improve the statistical sensitivity of monitoring horse mussel reefs whilst simultaneously focusing on the more sensitive indicators of fishing threats.
Article
Full-text available
Beds of Modiolus modiolus, in areas of moderate to strong tidal currents, develop into reefs with a relief of wave like undulations 0.09 – 0.45 m in amplitude and length scales of 6 – 18 m. Cores taken by diver operated suction sampler were targeted at positions on the ridges and troughs of a reef, in the Irish Sea off north-west Wales, allowing the fauna to be compared between adjoining ridges and troughs. Sessile epifauna was mostly attached to the larger mussels clumped together on the ridges. The crevice fauna and infauna were also nearly three times more abundant on the ridges, but the lists of species were similar from the two sub-habitats. Species richness was higher on the ridges, however, diversity and evenness measures were similar for ridges and trough samples. The Modiolus sub-habitats were found to be distinct from other macrofaunal assemblages in the wider southern Irish Sea. Deposition of faecal pellets in the spatially complex habitat amongst the mussels provided conditions suitable for an infauna more typical of inshore muddy sands enriched by organic matter. The scale of the ridge and trough morphology may increase variability between replicates when grabs are used remotely to sample this type of biogenic feature.
Article
Full-text available
Ecosystem services, the benefits that people obtain from ecosystems, are a powerful lens through which to understand human relationships with the environment and to design environmental policy. The explicit inclusion of beneficiaries makes values intrinsic to ecosystem services; whether or not those values are monetized, the ecosystem services framework provides a way to assess trade-offs among alternative scenarios of resource use and land- and seascape change. We provide an overview of the ecosystem functions responsible for producing terrestrial hydrologic services and use this context to lay out a blueprint for a more general ecosystem service assessment. Other ecosystem services are addressed in our discussion of scale and trade-offs. We review valuation and policy tools useful for ecosystem service protection and provide several examples of land management using these tools. Throughout, we highlight avenues for research to advance the ecosystem services framework as an operational basis for policy decisions.
Article
Full-text available
This study determined whether the acoustic roughness of Caribbean reef habitats is an accurate proxy for their topographic complexity and a significant predictor of their fish abundance. Fish abundance was measured in 25 sites along the forereef of Glovers Atoll (Belize). At each site, in situ rugosity (ISR) was estimated using the “chain and tape” method, and acoustic roughness (E1) was acquired using RoxAnn. The relationships between E1 and ISR, and between both E1 and ISR and the abundance of 17 common species and the presence of 10 uncommon species were tested. E1 was a significant predictor of the topographic complexity (r 2=0.66), the abundance of 10 common species of surgeonfishes, pomacentrids, scarids, grunts and serranids and the presence of 4 uncommon species of pomacentrids and snappers. Small differences in E1 (i.e. ∆0.05–0.07) reflected in subtle but significant differences in fish abundance (~1 individual 200m−2 and 116g200m−2) among sites. Although we required the use of IKONOS data to obtain a large number of echoes per site, future studies will be able to utilise RoxAnn data alone to detect spatial patterns in substrate complexity and fish abundance, provided that a minimum of 50 RoxAnn echoes are collected per site.
Article
Full-text available
We examined data on size of dominant demersal fish species in the SE Atlantic (44 species) and the NW Mediterranean (31 species) to determine whether there is a general tendency to increasing size towards deeper waters. Our results demonstrate significant positive size-depth relationships for most species examined (63% SE Atlantic and 74% NW Mediterranean). The relationships examined involved both a tendency towards greater size with increasing depth and a tendency towards smaller size towards shallower bottoms. The average (+/- standard error) rate of increase in fish length with increasing depth was found to be 0.09 +/- 0.01 cm length (m depth)-1 for the SE Atlantic species and 0.06 +/- 0.007 cm length (m depth)-1 for the NW Mediterranean species. In addition, we found the slope and intercept of these relationships to scale approximately to the 3/4 power of the maximum and minimum fish size respectively, showing that interspecific differences in the nature of this relationship depend on the size range of the different species. Consideration of several hypotheses to account for this general pattern suggests that it reflects a migratory (or diffusive) movement towards deeper waters during ontogeny, where fish benefit from the extended lives and lower metabolism at lower temperatures. We suggest this pattern is evolutionary in nature, and due to inherited behaviour.
Article
Full-text available
Stratified depth sampling was used to investigate the distributional changes of newly settled plaice Pleuronectes platessa and dabs Limanda limanda, and resident populations of shrimp Crangon crangon on a sandy beach. During the settlement period, the smallest newly settled plaice are found in deeper water than the larger fish that settled earlier. After settlement, plaice concentrate in water <1 m deep and there is a positive relationship between length and depth. Later in the year the fish gradually migrate into deeper water as they grow. Dabs settle later and in deeper water than plaice. Shrimp are concentrated in deeper water early in the year but migrate onshore in the summer, The movements of plaice are considered to be related to the predation risk caused by the shrimp and other predators in deeper water and to the higher temperatures in shallow water that promote faster growth. Once a size refuge from predators has been reached, the plaice move into deeper water. Intertidal pools probably serve as refuges for the smallest sizes of plaice because predators are less numerous in pools than in the sea. The use of shallow water by plaice represents the occupation of a niche which not only reduces predation and maximises growth, but may also greatly reduce competition for food in the earliest stages when densities are highest and competition with dabs is likely to be greatest.
Article
Full-text available
Biodiversity is rapidly declining worldwide, and there is consensus that this can decrease ecosystem functioning and services. It remains unclear, though, whether few or many of the species in an ecosystem are needed to sustain the provisioning of ecosystem services. It has been hypothesized that most species would promote ecosystem services if many times, places, functions and environmental changes were considered; however, no previous study has considered all of these factors together. Here we show that 84% of the 147 grassland plant species studied in 17 biodiversity experiments promoted ecosystem functioning at least once. Different species promoted ecosystem functioning during different years, at different places, for different functions and under different environmental change scenarios. Furthermore, the species needed to provide one function during multiple years were not the same as those needed to provide multiple functions within one year. Our results indicate that even more species will be needed to maintain ecosystem functioning and services than previously suggested by studies that have either (1) considered only the number of species needed to promote one function under one set of environmental conditions, or (2) separately considered the importance of biodiversity for providing ecosystem functioning across multiple years, places, functions or environmental change scenarios. Therefore, although species may appear functionally redundant when one function is considered under one set of environmental conditions, many species are needed to maintain multiple functions at multiple times and places in a changing world.
Article
Full-text available
Urban sprawl significantly impacts ecosystem services and functions. The exact impacts, however are difficult to quantify and are often neglected in policy making. The evaluation of ecosystem services is conducive to clarifying the ecological and environmental changes caused by urbanization. The objective of this study is to investigate variations in ecosystem services in response to land use changes during urbanization. The aim is to provide useful information and advice for policy makers concerned with sustainable development. Shenzhen, one of the fastest growing metropolitan areas in China, is selected as the study area. A fast evaluation method for ecological service values based on land use change was proposed and applied to the city for 1996, 2000 and 2004. The total value of ecosystem services in Shenzhen was 2776.0Â million Yuan in 1996, 2911.4Â million Yuan in 2000 and 2544.7Â million Yuan in 2004 respectively, with a decrease of 231.3Â million Yuan from 1996 to 2004 mainly due to the decreasing areas of woodland, wetland and water body. The combined ecosystem service value of woodland, wetland, water body and orchard was over 90% of the total value. Water supply and waste treatment were the top two service functions with high service value, contributing about 40% of the total service value. The results suggest that a reasonable land use plan should be made with emphasis on protecting wetland, water body and woodland, which have the highest ecosystem service value.
Book
Limitations of linear regression applied on ecological data. - Things are not always linear additive modelling. - Dealing with hetergeneity. - Mixed modelling for nested data. - Violation of independence - temporal data. - Violation of independence spatial data. - Generalised linear modelling and generalised additive modelling. - Generalised estimation equations. - GLMM and GAMM. - Estimating trends for Antarctic birds in relation to climate change. - Large-scale impacts of land-use change in a Scottish farming catchment. - Negative binomial GAM and GAMM to analyse amphibian road killings. - Additive mixed modelling applied on deep-sea plagic bioluminescent organisms. - Additive mixed modelling applied on phyoplankton time series data. - Mixed modelling applied on American Fouldbrood affecting honey bees larvae. - Three-way nested data for age determination techniques applied to small cetaceans. - GLMM applied on the spatial distribution of koalas in a fragmented landscape. - GEE and GLMM applied on binomial Badger activity data.
Article
Collaboration across sectors and disciplines is widely identified as essential for the implementation of ecosystem-based management (EBM) in both marine and terrestrial settings. However, relatively little research has examined the inner workings of collaborative marine EBM processes. Social network analysis (SNA) is a suite of methods for systematically analyzing and mapping relations between individuals or organizations, and can be used as a means of understanding the inner workings of collaboration. The authors applied SNA methods to cases of collaborative marine EBM planning in Rhode Island and New York, U.S.A., focusing on network structure and the role and influence of individual actors within their respective planning networks. Results highlighted the importance of diverse, decentralized networks of moderate density as well as the influence that bridging ties, or “brokers,” can wield in such processes. Research also found that non-governmental actors, such as university outreach specialists and scientists affiliated with environmental organizations, can be especially influential in collaborative marine EBM planning. This paper presents the results of this analysis, discusses the utility of this method for the analysis of collaborative marine EBM planning, and offers recommendations for future research and practice.
Article
The boreal bivalve Modiolus modiolus is common subtidally where it aggregates to form extensive, long-lived, biogenic habitats with a diverse associated flora and, especially, fauna. Despite this ecological importance, M. modiolus has not been described in terms of its functional morphology and overall biology. Modiolus modiolus is a typical epibenthic, suspension-feeding mytilid, albeit with anatomical modifications adapting it to a partially buried, gregarious lifestyle in a stable environment experiencing medium–high energy levels. The juvenile shell is covered partly in byssal setae secreted by the byssal gland and foot complex and becomes covered in sand grains held in place by a mucoid cement secreted by the dorsal mantle. The camouflaged shell at this vulnerable time probably serves as an anti-predator device. Individuals grow to maximum shell lengths of ∼60–213 mm, depending on depth and locality. With age (≥ 20–45 years), shells often become deformed, particularly posteriorly and around the byssal gape, thereby increasing reproductive capacity (gonadal volume) without increasing somatic growth. Information on the biology, reproductive strategy and life history traits of M. modiolus are reviewed. These field- and laboratory-derived data provide us with essential information to aid future research into the protection and conservation of this ecologically important biogenic habitat. This is because, today, dredging and fishery activities using bottom-towed gear have seriously damaged several M. modiolus habitats with deleterious impacts on ecosystem functioning. Post-impact recovery times are slow and dependent on both local and mega-population distributions.
Article
Side-scan sonar and underwater video were used to determine the impact of a trawl fishery on an epibenthic community associated with the horse mussel, Modiolus modiolus in a Northern Ireland sea lough. The presence of marks caused by trawl otter-boards on the sediments could be clearly seen using side-scan sonar and changes to the epibenthos are described from the video survey. It is apparent from the side-scan sonar survey that changes have occurred in the structure of the superficial sediments on heavily trawled areas. However, there was no clear indication of temporal changes. The utility of side-scan sonar coupled with GIS techniques to detect temporal and spatial effects is discussed.
Article
Marine inshore communities, including biogenic habitats have undergone dramatic changes as a result of exploitation, pollution, land-use changes and introduced species. The Firth of Forth on the east coast of Scotland was once home to the most important oyster (Ostrea edulis Linnaeus, 1758) beds in Scotland. 19th and early 20th century fisheries scientists documented the degradation and loss of these beds, yet transformation of the wider benthic community has been little studied. We undertook archival searches, ecological surveys and shell community analysis using radioisotope dated sediment cores to investigate the history of decline of Forth oyster beds over the last 200 years and the changes to its wider biological communities. Quadrat analysis of the present day benthos reveal that soft-sediment communities dominate the Firth of Forth, with little remaining evidence of past oyster beds in places where abundant shell remains were picked up by a survey undertaken in 1895. Queen scallops (Aequipecten opercularis Linnaeus, 1758) and horse mussels (Modiolus modiolus Linnaeus, 1758) were once common within the Forth but have also markedly decreased compared to the earlier survey. Ouranalyses of shell remains suggest that overall mollusc biomass and species richness declined throughout the 19th century and early 20th century, suggesting broader-scale community change as human impacts increased and as habitats degraded. Inshore communities in the Firth of Forth today are less productive and less diverse compared to past states, with evidence suggesting that most of the damage was done by early bottom trawling and dredging activities. Given the pervasive nature of intensive trawling over the past 150 years, the kind of degradation we document for the Firth of Forth is likely to be commonplace within UK inshore communities.
Article
Managing a complex ecosystem to balance delivery of all of its services is at the heart of ecosystem-based management. But how can this balance be accomplished amidst the conflicting demands of stakeholders, managers, and policy makers? In marine ecosystems, several common ecological mechanisms link biodiversity to ecosystem functioning and to a complex of essential services. As a result, the effects of preserving diversity can be broadly beneficial to a wide spectrum of important ecosystem processes and services, including fisheries, water quality, recreation, and shoreline protection. A management system that conserves diversity will help to accrue more "ecoservice capital" for human use and will maintain a hedge against unanticipated ecosystem changes from natural or anthropogenic causes. Although maintenance of biodiversity cannot be the only goal for ecosystem-based management, it could provide a common currency for evaluating the impacts of different human activities on ecosystem functioning and can act as a critical indicator of ecosystem status.
Article
The production and nutritional quality of faeces and pseudofaeces from the horse mussel Modiolus modiolus (Dillwyn) was measured during the spring diatom bloom in Logy Bay, Newfoundland. Chloropigments, organic carbon, organic nitrogen and biogenic silica were determined in faeces and pseudofaeces, and compared with values from seston samples. The biodeposition rate of a horse mussel (faeces and pseudofaeces) of 5 g dry meat weight varied from 40.9 mg dry weight · day−1 at the peak of the bloom to 4–8 mg · day−1 at the end. The concentrations of organic carbon and organic nitrogen were lower in the faeces and pseudofaeces than in the seston, but chlorophyll a levels were greater in the pseudofaeces than in the seston or faeces. In terms of dry weight, faeces production was five or more times greater than pseudofaeces production, but the latter were more important in recycling chlorophyll a, especially during the peak of the diatom bloom. Microscopic analysis of the biodeposits showed that chains and large diatoms were very abundant in the pseudofaeces, whereas the faeces contained only frustules of small cells and of short chains, indicating that M. modiolus concentrates the large diatoms contained in the seston and rejects them in the pseudofaeces. The rejection of organic-rich diatoms by M. modiolus during the spring bloom provides a mechanism for the recycling of nutrients to suspension-feeders and deposit-feeders.
Article
The relationship between biological community structure and particle size composition is investigated in coastal deposits off the southeast of England. Sediments in the survey area fall into well-defined groups when analysed by multivariate techniques, indicating similarities and differences which could not be identified by mere inspection of the data. Biological resources also fall into relatively distinct groups, or communities, when analysed for species composition and population density, although similarity within the groups is lower than that obtained for the sediments. There is, however, little evidence of a close correspondence between the distribution of different sediment types and benthic communities in the survey area: comparison of the similarity matrices yields weighted Spearman rank correlation of less than 0.37. This suggests that factors other than sediment composition play a significant part in controlling biological community structure on the seabed. Still, there is evidence that some species such as the tube-dwelling worm Sabellaria spinulosa are associated mainly with sands and gravels whilst fine mobile silts and sands are characterized by 'opportunistic' species such as the tube-worm Lagis koreni. The results suggest that although modification of sediment composition from mixed sands and gravels to silts would be expected to result in colonization by 'opportunistic' species capable of survival in mobile deposits, restoration of sediment composition after cessation of dredging for marine aggregates is not, within broad limits, a prerequisite for establishment of biological communities which are comparable with those that occurred in the deposits prior to dredging.
Article
Fisheries can have profound effects on epifaunal community function and structure. We analyzed the results from five dive surveys (1975–1976, 1980, 1983, 2003 and 2007), taken in a Special Area of Conservation, Strangford Lough, Northern Ireland before and after a ten year period of increased trawling activity between 1985 and 1995. There were no detectable differences in the species richness or taxonomic distinctiveness before (1975–1983) and after (2003–2007) this period. However, there was a shift in the epifaunal assemblage between the surveys in 1975–1983 and 2003–2007. In general, the slow-moving, or sessile, erect, filter-feeders were replaced by highly mobile, swimming, scavengers and predators. There were declines in the frequency of the fished bivalve Aequipecten opercularis and the non-fished bivalves Modiolus modiolus and Chlamys varia and some erect sessile invertebrates between the surveys in 1975–1983 and 2003–2007. In contrast, there were increases in the frequency of the fished and reseeded bivalves Pecten maximus and Ostrea edulis, the fished crabs Cancer pagurus and Necora puber and the non-fished sea stars Asterias rubens, Crossaster papposus and Henricia oculata between the surveys in 1975–1983 and 2003–2007. We suggest that these shifts could be directly and indirectly attributed to the long-term impacts of trawl fishing gear, although increases in the supply of discarded bait and influxes of sediment may also have contributed to changes in the frequency of some taxa. These results suggest that despite their limitations, historical surveys and repeat sampling over long periods can help to elucidate the inferred patterns in the epifaunal community. The use of commercial fishing gear was banned from two areas in Strangford Lough in 2011, making it a model ecosystem for assessing the long-term recovery of the epifaunal community from the impacts of mobile and pot fishing gear.
Article
Surveys by digital side-scan sonar, RoxAnnTM acoustic ground discrimination systems, multibeam echosounder and a sub-bottom profiling system showed that a Modiolus modiolus reef, in the Irish Sea off Pen Llŷn, north-west Wales, had a distinctive morphology and acoustic characteristics. The extent of the reef could therefore be determined and the benthic structure reliably mapped. The biogenic reef is in an area with moderately strong tidal currents and overlays lag gravel and cobbles with patchy sand veneers. The mussels form an undulating surface, orientated perpendicular to the current, with an average wavelength of 11.7 m and amplitude of 0.24 m that is significantly different from the surrounding seabed. Reef deposits reach a thickness of 1 m on top of the underlying lag gravels. The characteristic reef surface morphology helps distinguish the reef from the surrounding seabed on side-scan sonar and multibeam echosounder records and the undulations create the spatial complexity that influences the small-scale distribution of the associated epifauna, and infauna, reported in papers II and III of this series. The M. modiolus reef was recorded in the same location 40 y ago and has probably persisted there for over 150 y. Monitoring implications are discussed.
Article
We examine the use of prey resources and seasonal variations in behaviour and reproduction for the whelk Buccinum undatum, the most abundant subtidal carnivore in the northern Gulf of St. Lawrence. Whelks used in this study were collected in the Mingan Islands in 1987 and 1988. The proportion of whelks with food in their stomachs varies seasonally and further with habitat, being greatest on sandy bottoms. It decreases at the onset of breeding in the spring and is generally low through the summer. Fragments of certain organisms (e.g. polychaetes, bivalves, urchins) in whelk stomachs suggest that they are active predators. However, predation is virtually never seen in the field. Other organisms in the stomachs, infrequent feeding, and their high mobility and capacity to detect and locate dead animals on the bottom suggest that whelks are carrion feeders. However, the amount of carrion available is probably insufficient to meet the needs of the biomass of whelks present in these waters. An interaction with seastars may contribute to the whelk's diet. They frequently approach seastars which are extracting bivalves from sediment bottoms and may benefit by feeding on prey remains left by seastars or by foraging in sediments recently disturbed by seastars.
Article
The term nursery implies a special place for juvenile nekton (fishes and decapod crustaceans) where density, survival, and growth of juveniles and movement to adult habitat are enhanced over those in adjoining juvenile habitat types. We reviewed recent literature concerning these four topics and conducted meta-analyses for density and survival data. Most studies of mangroves as nurseries have addressed only occurrence or density of fishes or decapods, have not used quantitative sampling methods, and have not compared alternate habitats. Comparison of nekton densities among alternate habitats suggests that, at times, lower densities may be typical of mangroves when compared to segrass, coral reef, marsh, and non-vegetated habitats. There is little direct consumption of mangrove detritus by nekton. C, N, and S isotope studies reveal little retention of mangrove production by higher consumers. Densities of prey for transient fishes and decapods may be greater within mangroves than elsewhere, but there has been no verification that food availability affects growth or survival. Experimental evidence indicates that mangrove roots and debris provide refuge for small nekton from predators, thus enhancing overall survival. There is no evidence that more individuals move to adult habitats from mangroves than from alternate inshore habitats. There is an obvious need to devise appropriate experiments to test the nursery functions of mangroves. Such data may then be one more reason to add support for mangrove conservation and preservation.
Article
Human damage to biogenic substrata such as maerl has been receiving increasing attention recently. Maerl forms highly biodiverse and heterogeneous habitats composed of loose-lying coralline red algae, which fulfil nursery area prerequisites for queen scallops (Aequipecten opercularis) and other invertebrates. The benefits obtained by queen scallops utilising maerl were poorly understood, so we used both laboratory predation and field tethering experiments to investigate the refuge and growth potential provided by pristine live maerl (PLM) grounds over other common substrata. In aquaria, more juvenile queen scallops (<35 mm shell height) survived on PLM than on gravel substrata in the presence of the crab Carcinus maenas or the starfish Asterias rubens. Field tethering experiments indicated similar survivorship of juvenile queen scallops on PLM than gravel; additionally, their growth rates were similar on both substrata. PLM allows scallops to seek refuge from predators and position themselves to optimise their food supply. Other bivalve refugia have been shown to provide poor food supply as a consequence of their high heterogeneity, yet maerl grounds provide a ‘win–win’ scallop nursery area coupling refuge availability with high food supply.
Article
This paper investigates the equity implications of marketing ecosystem services in protected areas and rural communities. We use a three-tiered equity framework to analyse four distinct efforts to commercialise watershed recharge and carbon dioxide fixation by forests in Meso-America. We show that project development and participation are strongly mediated by organisational networks, as well as existing rights of access over land and forest resources. We demonstrate that procedural fairness diverges strongly when initiatives are implemented in protected areas or in rural communities. While in the former reserve managers and intermediaries concentrate all decision-making power, initiatives working with rural communities are able to integrate more significantly service providers in management decisions. Marketing ecosystem services in protected areas contributes to reduce expenditure rates for protected area management, but also results in less equitable outcomes, as rural communities and forest resource users become excluded from receiving sustained development benefits. When ecosystem services are commercialised by rural farmers, payments do not cover opportunity costs but act as a significant incentive for participation in most cases. Ecosystem service providers also benefit from complementary project activities, such as forest management training and agricultural extension support. We argue that limited economic impact and existing inequities in decision-making and outcomes can be explained by problems of institutional design, in particular the inability of markets and payments for ecosystem services to account for context-related factors, such as property rights.
Article
The benthic macroinvertebrate fauna, sediments and water column were monitored at monthly intervals for 13 months at 13 sites in the canal systems of the Gold Coast, Queensland, Australia. A total of 65 taxa and 4195 individuals were collected. The 25 taxa selected for statistical analysis comprised 94.8% of the total abundance. Patterns in invertebrate distributions were analysed by principal component analysis and were related to environmental variables by multiple regression analysis. Two broad benthic community types were defined. One restricted in distribution to dead end locations and characterized by low diversity, low species richness and dominated by Minuspio cirrifera, while the other was distributed in connecting canals and characterized by high species richness and high diversity. The distribution of species, and hence the distribution of community types, was related largely to the quality of the dissolved oxygen environment, which was described by mean dissolved oxygen percentage saturation, standard deviation of saturation and mean percentage sulphur content of sediment. A progressive transition between community types resulting from a deterioration in the quality of the dissolved oxygen environment was evident with increasing distance from source waters in both connecting canals and dead-end locations. Variance in community structure was also explained by sediment type (grain size) to some extent. Sediments became finer with a decrease in the tidal prism and tidal velocity, and were finest at dead-end locations. Results suggest that residential canals should be as short as possible, and dead-ends should be avoided in order to maintain good water quality.
Article
Herbivore damage is generally detrimental to plant fitness, and the evolu- tionary response of plant populations to damage can involve either increased resistance or increased tolerance. While characters that contribute to resistance, such as secondary chem- icals and trichomes, are relatively well understood, characters that contribute to a plant's ability to tolerate damage have received much less attention. Using Helianthus annuus (wild sunflower) and simulated damage of Haplorhynchites aeneus (head-clipping weevil) as a model system, we examined morphological characters and developmental processes that contribute to compensatory ability. We performed a factorial experiment that included three levels of damage (none, the first two, or the first four inflorescences were clipped with scissors) and eight sires each mated to four dams. We found that plants compensated fully for simulated head-clipper damage and that there was no variation among plant families in compensatory ability: seed production and mean seed mass did not vary among treat- ments, and sire X treatment interactions were not significant. Plants used four mechanisms to compensate for damage: (1) Clipped plants produced significantly more inflorescences than unclipped plants. Plants produced these additional inflorescences on higher order branches at the end of the flowering season. (2) Clipped plants filled significantly more seeds in their remaining heads than did unclipped plants. (3) Clipped plants, because they effectively flowered later than unclipped plants, were less susceptible to damage by seed- feeding herbivores other than Haplorhynchites. (4) In later heads, seed size was greater on clipped plants, which allowed mean seed size to be maintained in clipped plants. Although there was genetic variation among the families used in this experiment for most of the characters associated with compensation for damage (seed number, mean seed size, mean flowering date, length of the flowering period, and branching morphology), in analyses of these characters, no sire X treatment interactions were significant indicating that all of the families relied on similar mechanisms to compensate for damage.
Article
Pseudoreplication is the failure of a statistical analysis to properly incorporate the true structure of randomness present in the data. It has been well documented and studied in the ecological literature but has received little attention in the fisheries literature. Avoiding pseudoreplication in analyses of fisheries data can be difficult due to the complexity of the statistical procedures required. However, recent developments in statistical methodology are decreasing the extent to which pseudoreplication has to be tolerated. Seven examples are given here, beginning with simple design-based remedies and progressing to more challenging examples including the model-based remedies of mixed-effects modelling, generalized linear mixed models, state-space models, and geostatistics.
Article
Human domination of the biosphere has greatly altered ecosystems, often overwhelming their capacity to provide ecosystem services critical to our survival. Yet ecological understanding of ecosystem services is quite limited. Previous work maps the supply and demand for services, assesses threats to them, and estimates economic values, but does not measure the underlying role of biodiversity in providing services. In contrast, experimental studies of biodiversity-function examine communities whose structures often differ markedly from those providing services in real landscapes. A bridge is needed between these two approaches. To develop this research agenda, I discuss critical questions and key approaches in four areas: (1) identifying the important 'ecosystem service providers'; (2) determining the various aspects of community structure that influence function in real landscapes, especially compensatory community responses that stabilize function, or non-random extinction sequences that rapidly erode it; (3) assessing key environmental factors influencing provision of services, and (4) measuring the spatio-temporal scale over which providers and services operate. I show how this research agenda can assist in developing environmental policy and natural resource management plans.