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Abstract

Since the 1950s, invertebrate fisheries catches have rapidly expanded globally to more than 10 million tonnes annually, with twice as many target species, and are now significant contributors to global seafood provision, export, trade and local livelihoods. Invertebrates play important and diverse functional roles in marine ecosystems, yet the ecosystem effects of their exploitation are poorly understood. Using 12 ecosystem models distributed worldwide, we analysed the trade-offs of various invertebrate fisheries and their ecosystem effects as well as ecological indicators. Although less recognized for their contributions to marine food webs, our results show that the magnitude of trophic impacts of invertebrates on other species of commercial and conservation interest is comparable with those of forage fish. Generally, cephalopods showed the strongest ecosystem effects and were characterized by a strong top-down predatory role. Lobster, and to a lesser extent, crabs, shrimp and prawns, also showed strong ecosystem effects, but at lower trophic levels. Benthic invertebrates, including epifauna and infauna, also showed considerable ecosystem effects, but with strong bottom-up characteristics. In contrast , urchins, bivalves, and gastropods showed generally lower ecosystem effects in our simulations. Invertebrates also strongly contributed to benthic–pelagic coupling , with exploitation of benthic invertebrates impacting pelagic fishes and vice versa. Finally, on average, invertebrates produced maximum sustainable yield at lower levels of depletion (~45%) than forage fish (~65%), highlighting the need for management targets that avoid negative consequences for target species and marine ecosystems as a whole.

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... Marine fisheries are of utmost importance for the economy and wellbeing of coastal communities, providing job opportunities and fishery products with high nutritional value (Anderson et al., 2011;FAO, 2018). The world's marine fisheries increased continuously from 1950 to a production peak in 1996 but have since exhibited a general declining trend, with interannual fluctuations (Eddy et al., 2017;FAO, 2018). However, since 1950, global invertebrate fisheries have increased in volume and value in several countries (Anderson et al., 2011;FAO, 2018;Leiva and Castilla, 2002). ...
... The increase in invertebrate fisheries was partially a response to decreasing finfish stocks caused by the search of target species until then under-exploited (Anderson et al., 2008;Farmery et al., 2020;Pauly et al., 2002). In this context, global invertebrate catches have expanded to more than 10 million tons annually, doubling the number of target species since the 1950 s (Eddy et al., 2017;FAO, 2018). This involved the development of new fisheries for crustaceans, mollusks, and echinoderms (Anderson et al., 2011;Eddy et al., 2017). ...
... In this context, global invertebrate catches have expanded to more than 10 million tons annually, doubling the number of target species since the 1950 s (Eddy et al., 2017;FAO, 2018). This involved the development of new fisheries for crustaceans, mollusks, and echinoderms (Anderson et al., 2011;Eddy et al., 2017). However, these fisheries are far from being sustainable, since 34% of invertebrate fisheries were classified as over-exploited, collapsed or closed by the mid-2000 ′ s (Anderson et al., 2011;FAO, 2018). ...
Article
Marine gastropods are key items in small-scale fisheries worldwide, generating employment and high economic value in international markets. In North Patagonian Gulfs (Southwestern Atlantic), gastropods are landed as by-catch in bivalve artisanal fisheries, and thus no official statistics are reported. Recently, the first regulation of marine gastropod catches was established based on size at maturity for some edible species. However, additional biological-fishery data are necessary for developing a management plan if a regulated small-scale fishery is to be established. We provide the first preliminary estimation of the harvestable stock and other basic biological parameters of gastropods in the San José Gulf (SJG), a Natural Protected Area in Northern Patagonia. Density assessments are usually carried out using dredges or trawl nets that damage marine substrata, and thus we used data from non-destructive, drifting underwater visual census in transects, integrated with a Geographic Information System. We estimated the biomass, density, CPUE and the harvestable stock of Odontocymbiola magellanica and Buccinanops cochlidium, the main species currently landed in SJG. Visual surveys were conducted in 85,000 m², where both species were present in depths ranging from 5 to 20 m depth. For O. magellanica, the maximum densities were 0.02–0.04 individuals m⁻² with maximum CPUE of 12.8 kg diver⁻¹ 15 min⁻¹ and estimated harvestable biomass of 837.05 kg (S.D. = 189.96), whereas for B. cochlidium densities were 0.32–0.60 individuals m⁻² with maximum CPUE of 9.25 kg diver⁻¹ 15 min⁻¹ and 365.12 kg (S.D. = 81.86) of harvestable biomass. The delayed maturity and reproductive strategies of both species, among other biological parameters, require a precautionary approach. The total exploitable biomass estimated in our work clearly highlights the need for a very selective, small-scale fishery, operating under a well enforced management plan regulating their capture to ensure its sustainability in a Natural Protected Area.
... Globally, fisheries catches have declined since the mid-1990s (Pauly and Zeller, 2016) due to the depletion of many traditional target species, which has been accompanied by the emergence of new or intensified fisheries for non-traditional species, such as many invertebrates (Anderson et al., 2011a;Eddy et al., 2016). However the knowledge base with which to evaluate the impacts of these expanding invertebrate fisheries is limited (Anderson et al., 2008(Anderson et al., , 2011b. ...
... However the knowledge base with which to evaluate the impacts of these expanding invertebrate fisheries is limited (Anderson et al., 2008(Anderson et al., , 2011b. Many invertebrate species fetch high market prices (Swartz et al., 2013) and demand is increasing, yet for many stocks there are no formal stock assessments nor management plans in place (Anderson et al., 2008(Anderson et al., , 2011bEddy et al., 2016). The RAM legacy stock assessment database includes only 36 invertebrate stocks of a total of 331 stocks from 21 national and international agencies (Ricard et al., 2011). ...
... Studies investigating the ecosystem impacts of fishing finfish (Bundy et al., 2009;Worm et al., 2009) and low-trophic levels (e.g. forage fish; Smith et al., 2011) have indicated strong impacts on other species in the ecosystem, and recently, studies also indicate that some invertebrates, including lobster, can play strong ecosystem roles as both predators and prey (Coll et al., 2013;Eddy et al. 2016). ...
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In New Zealand and Nova Scotia, lobster (Jasus edwardsii and Homarus americanus, respectively) is the most valuable export fishery. Although stock assessments and indicators assist in evaluating lobster fisheries, ecosystem effects are largely unknown, hindering ecosystem-based fisheries management (EBFM). We employed ecosystem models for the Cook Strait, New Zealand and western Scotian Shelf, Nova Scotia, Canada, to evaluate trade-offs between catches and ecosystem impacts in lobster fisheries from single- and multi-species perspectives. We ran simulations to independently determine exploitation rates that produced maximum sustainable yield (MSY) for lobster, and for all fished groups. We then ran simulations using these MSY exploitation rates simultaneously, and simulations to maximize multi-species MSY (MMSY). Our results indicate that current lobster exploitation rates in both regions are greater than those producing MSY, and have significant ecosystem impacts. Simulating multi-species fisheries, in both systems the sum of single-species MSY for all fished groups was less than the sum of catches where exploitation rates were run simultaneously. Runs maximizing MMSY across the entire ecosystem increased exploitation rates on many fished groups, and produced even greater total catch—yet with much greater ecological costs—and in Nova Scotia, collapses of sharks, large predators, and lobster themselves. As fisheries management moves towards multi-species and ecosystem-based approaches, we suggest that MMSY targets should be treated similarly to MSY—not as a target, but a limit. Even then, careful evaluation is required before implementation to ensure that there are no undesirable economic or ecological consequences.
... Traditional small-scale invertebrate fisheries existed around the world for centuries, but in the last decades those have rapidly expanded, and many new fishery areas and practices have emerged (Anderson et al. 2011;Eddy et al. 2017). In the last six years, new record catches have been registered for three invertebrate groups-lobsters, shrimps and cephalopods . ...
... In the last six years, new record catches have been registered for three invertebrate groups-lobsters, shrimps and cephalopods . These days, with more than 10 million tons caught annually, and accounting for about 14% of global catches (Eddy et al. 2017;, invertebrate fisheries represent an important socioeconomic component of coastal communities. Furthermore, with the gradual fishing down of food webs, there is an evidence of invertebrate species replacing depleted predator fish at higher trophic levels in marine environment (Molfese et al. 2014;Rogers-Bennett and Juhasz 2014). ...
... Yet, excluding few highly profitable species, invertebrates fisheries received much less scientific and management attention than most of the exploited vertebrate species so far (Anderson et al. 2011;Eddy et al. 2017). Consequently, for a majority of commercially important invertebrates, accurate data on abundance, population structure and connectivity is lacking, and their stocks are neither effectively assessed nor managed (Anderson et al. 2011;Eddy et al. 2017). ...
Article
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With gradual decline of global finfish resources, fisheries targeting cephalopods expanded. Yet, the stock assessment and management practice are frequently lacking, and existing ones often remain poorly suited for cephalopod unique life-history. In light of increasing ecological disturbances in marine ecosystems worldwide, assessing exploited species' status and response becomes vital for devising effective strategies that would ensure their sustainable management. There is generally scarce understanding of the way fisheries and other environmental stressors exert their combined effects on cephalopods stock dynamic and long-term resilience. To that end, evolutionary-based population studies that inform on identity, connectivity and adaptive potential of natural populations present a unique opportunity for assessing the viability of exploited cephalopod stocks. Such studies have been revolutionized in the last decade by proliferation of next generation sequencing technologies. They offer new avenues for expanding our knowledge, especially on population structure and the evolutionary responses to shifts in environmental pressures. In this paper we elaborate on how deep genomic insights into demographic and evolutionary status of fished cephalopods could improve their stock assessment and management practice. We also propose that the common octopus Octopus vulgaris would be a suitable model species to test the power of evolutionary tools to inform fishery scientists and managers on biological questions relevant for their sustainable exploitation.
... In recent decades, fishing pressure on marine invertebrates has increased, and some fisheries targeting this group have already exceeded sustainable limits of exploitation (Anderson et al., 2011). In pelagic ecosystems, fishing can reduce the efficiency of the "top-down" energy control that predators, such as squid, exert on lower trophic levels (Eddy et al., 2017). In benthic ecosystems, an excessive reduction in the biomass of low-trophic-level invertebrates, such as shrimp, may affect the size of third-and fourth-order predator populations (Eddy et al., 2017). ...
... In pelagic ecosystems, fishing can reduce the efficiency of the "top-down" energy control that predators, such as squid, exert on lower trophic levels (Eddy et al., 2017). In benthic ecosystems, an excessive reduction in the biomass of low-trophic-level invertebrates, such as shrimp, may affect the size of third-and fourth-order predator populations (Eddy et al., 2017). Despite these ecological effects, no relationship has been found between these effects and the increase in extinction risk of marine invertebrates. ...
... To determine whether marine invertebrate species present and absent in conservation lists differed in average weight, the difference between population means from independent samples was tested (Dytham, 2013), setting a significance level of 0.05. A logistic regression model was applied to calculate the degree of dependence between the weight of the species and their presence or absence in the conservation lists. ...
Article
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In tetrapods, body weight (BW) is a reliable predictor of extinction risk as it is representative of their life cycle, physiology, and ecology: low BW species tend to be less vulnerable compared to larger ones. In marine fish, excepting elasmobranchs, sturgeon, and salmonids, this relationship is not statistically significant; and in marine invertebrates it is unknown. In this study, the BW was evaluated as a predictor of extinction vulnerability in marine invertebrates at two taxonomic levels, assuming that endangered species lists indicate true extinction risk. At the order level, a correlation was performed between BW and the proportion of species in conservation lists concerning the total number of species (TS) of 17 orders. At the species level, we compared the average BW of listed versus not listed species by fitting a logistic regression between the BW and the presence/absence of species in these lists. We found no relationship between TS and BW, but there was a significant difference in the BW of listed versus not listed species. The relationship between the BW and the presence/absence of species in conservation lists was weaker in marine invertebrates compared to that in tetrapods and fish. The BW is an unreliable predictor of extinction risk in marine invertebrates. Thus conservation efforts should focus on maintaining and restoring the microhabitat of invertebrate species.
... Naturally stressed ecosystems, such as estuaries, show low CI values (Lobry et al., 2008). CI also decreases under stressing conditions such as fishing impacts (Eddy et al., 2017). ...
... Fishing mortality, and particularly overfishing, can have impacts on ecosystem functioning. Eddy et al., (2017) studied the ecosystem effects of invertebrate fisheries by analysing twelve ecosystem models worldwide. These authors demonstrated the important role of invertebrates in marine ecosystems and that their exploitation can have strong ecosystem impacts with a reduction in ecosystem connectance (CI). ...
... Cephalopods had the highest CI values and low relative abundance indicating their strong predatory role in the various studied ecosystems and thus, underlying their top-down regulation role in these ecosystems. Overall, Eddy et al., (2017) concluded that relative abundance and CI of exploited invertebrate groups were good predictors of ecosystem impacts. ...
Article
The Water Framework Directive (article 2, paragraph 21) as well as the Marine Strategy Framework Directive (MSFD, Descriptor 4) stress the need for assessing the quality of the structure and the functioning of ecosystems. The MSFD also underlines the urgent need for development, testing, and validation of ecosystem state indicators. Holistic function-based criteria and indicators as provided by Ecological Network Analysis (ENA) could be used to define and assess the 'Good Environmental Status' of marine ecosystems. This approach also feeds Ecosystem Based Management (EBM). ENA generally analyses the fluxes' quality of a single medium such as here the carbon fluxes in a food web and produces a number of useful metrics that indicate, inter alia, the total carbon flow through the system, the quality of the functioning of the system or the trophic efficiency of system. A short list of indices [i.e. Detritivory over Herbivory ratio (D/H), Connectance Index (CI), Transfer Efficiency (TE) over trophic levels, System Omnivory Index (SOI), Finn's Cycling Index (FCI), relative Redundancy (R/DC), Average Mutual Information (AMI) and Interaction Strength (IS)] is proposed for practical use. This paper presents a first framework for OSPAR Regional Sea Convention food web indicators based on ENA. These are presented here focusing on their applicability and what is needed for implementation, illustrating their potential use by case studies.
... Despite its value, a holistic assessment of the food web structure and function is not easy (Libralato et al., 2014). Often data of all trophic levels are not available (Corrales et al., 2017b;Eddy et al., 2017), cost a lot (Robinson et al., 2010) and/or are difficult to collect. Food web assessments are often restricted by knowledge gaps on species biomasses, diets, mortalities and unreported catches (Barausse et al., 2009). ...
... Moreover, our results show that the majority of studies have investigated food webs at a subnational level or supranational level, indicating that studies tend to focus on specific water bodies rather than cover vast marine geographic areas. Nevertheless, as mentioned above, enhanced computer power and new modeling approaches have also allowed the processing of extensive time series thus facilitating the study and comparison of coastal shelf food webs over large spatial scales (i.e., at a national or even global scale; Pauly and Christensen, 1995), as well as their evolution over extensive time scales (more than 400 years) so as to forecast and project future trends in response to global change or other sources of ecosystem alteration (e.g., Hoover et al., 2013;Neira et al., 2014;Hattab et al., 2016;Eddy et al., 2017). Still, approaches that are largely driven by administrative boundaries and access to data often limit the validity of the outputs, as political boundaries commonly do not reflect meaningful ecological boundaries. ...
Article
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The study of marine coastal food webs has a central role in the application of the integrated ecosystem approach for marine management. Changes in food webs caused by natural or anthropic drivers can lead to dramatic shifts in the overall structure and function of coastal marine ecosystems and deterioration of their services. The present review investigates the methodological approaches employed for the assessment of coastal shelf food webs at a global scale and highlights existing gaps and limitations. Out of 1652 published articles that initially met our search criteria, 880 passed the initial screening and 493 were found relevant and were fully analyzed. The information extracted included the spatiotemporal coverage of the studies; the main methodological approaches utilized for the assessment of population state variables (i.e., biomass, size, abundance) and trophic levels; the biotic components and driving factors considered; indices used to describe the structure and functioning of coastal food webs; and main knowledge gaps. Results showed that most studies have been conducted at a subnational level, mostly in the Temperate Northern Atlantic marine realm. Overall, 54% of the studies provided quantitative information on food web structure. The most common methodological approach utilized was modeling (40%), followed by non-experimental-based correlations (30%), and natural or manipulative experiments (14%). Information on population state variables was provided by 69% of the studies, while 42% employed some of the following trophic level determination techniques: stable isotopes, gut contents, fatty acids, and molecular analysis, which were either combined or used in isolation. Specific natural or human drivers were incorporated in 76% of the studies, with fishing being the most common driver. Modeling approaches included multiple indices to describe food web attributes and/or the structure and functioning of coastal shelf ecosystems. Despite the great progress achieved through the development of new tools and techniques, food web analysis still suffers from important knowledge gaps and limitations of the methodological approaches, which are extensively discussed. The present review establishes a useful knowledge base to provide guidance for future research and assessments on coastal shelf food webs, and to support ecosystem-based management.
... Lobsters can show relatively strong ecosystem effects, particularly at lower trophic levels given their omnivorous habits (Eddy et al. 2017). Worldwide several examples exist of lobsters playing a key role in mediating trophic cascades (Eddy et al. 2017;Lafferty 2004). ...
... Lobsters can show relatively strong ecosystem effects, particularly at lower trophic levels given their omnivorous habits (Eddy et al. 2017). Worldwide several examples exist of lobsters playing a key role in mediating trophic cascades (Eddy et al. 2017;Lafferty 2004). For example, off South Africa lobster predation of urchins has negative implications for abalone recruits that use the urchins as shelter (Blamey et al. 2014). ...
Article
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Australia’s lobster fisheries are relatively small in volume (9500t) compared with global production (289,000t), but are the country’s most valuable in terms of both overall production and value of export (2014 Gross Value of Production of $610 million AUD). Further, they support commercial, recreational and indigenous fishers along most of the jurisdictions, support significant fisheries. Catches of western rock lobster Panulirus cygnus dominate landings (61%), followed by southern rock lobster Jasus edwardsii, tropical lobster Panulirus ornatus and the eastern rock lobster Sagmariasus verreauxi. Large-scale environmental influences such as climate change are impacting on these fisheries in similar or different ways forcing new management and raising the need for greater resilience in current supply chains. Although these are separate fisheries, the integrated nature of the dominant Chinese export markets suggests potentially important economic and market related interactions. Our overview highlights the critical role of continued monitoring of recruitment pulses, in combination with robust harvest strategies, to ensure that harvests respond adequately and fisheries achieve biological and economic sustainability. Approaches that also include socio-cultural considerations (triple bottom line) are important given many fisheries include indigenous Australians. Our integrated analysis of Australian lobster fisheries highlights differences and similarities with spiny lobster fisheries worldwide and lessons from opportunities, including adapting to new free trade agreements, enhancing the reputation of wild lobsters as a whole, sharing expertise, and better alignment of supply and demand.
... Increased fishing for invertebrates (including squid, shrimp, crabs, and shellfish) consistently led to higher catch and value in most of our simulated ecosystems, with minimal effects on indicators of ecosystem structure. In contrast to this, Eddy et al. (2017) found that increasing fishery exploitation rates of invertebrates using a global suite of Ecopath with Ecosim (EwE) models had considerable ecosystem wide effects, though typically those increases in fishing rates and declines in invertebrate biomass were stronger than what we tested here. Our results for fishing scenarios (particularly in Supporting Information) demonstrated that removal of fishing caused larger changes to the ecosystem and fishery structure than did doubling of fishing. ...
... Invertebrates are typically represented as bulk biomass pools in Atlantis (and other ecosystem-level models) and as such may not be capturing their ecological processes with sufficient nuance. Consequently, these findings should be taken as preliminary indicators only and more detailed case-specific consideration should be given to any particular system looking to significantly increase pressure on invertebrate stocks, so as to avoid unintended negative consequences (Eddy et al., 2017). ...
Article
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Ecosystem-based management (EBM) of the ocean considers all impacts on and uses of marine and coastal systems. In recent years, there has been a heightened interest in EBM tools that allow testing of alternative management options and help identify tradeoffs among human uses. End-to-end ecosystem modelling frameworks that consider a wide range of management options are a means to provide integrated solutions to the complex ocean management problems encountered in EBM. Here, we leverage the global advances in ecosystem modelling to explore common opportunities and challenges for ecosystem-based management, including changes in ocean acidification, spatial management, and fishing pressure across eight Atlantis (atlantis.cmar.csiro.au) end-to-end ecosystem models. These models represent marine ecosystems from the tropics to the arctic, varying in size, ecology, and management regimes, using a three-dimensional, spatially-explicit structure parametrized for each system. Results suggest stronger impacts fro
... Fishing is among the most worrisome stressor to BPC across short temporal scales [4,18] and the progressive expansion of fisheries to deeper environments [19,20] has the potential to produce unprecedented disturbances on deep communities with detrimental consequence on ecosystems [21][22][23][24][25]. Indeed, fishing can severely impact on taxa relevant for BPC [26] also through mortality of organisms in their different life stages. Unwanted catches discarded at sea constitute organic matter that sinks to the sea bottom contributing to BPC. ...
... Interestingly, it has been recently suggested that the increasing depletion of top predators over the past decades, has led to a shift of fisheries towards forage fish and benthic invertebrates [92] that could have an important role in BPC [26]. Forage fish have been also recognized as wasp-waist species [93] exerting a double important role: top-down on their prey and bottom-up on their predators. ...
Article
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Benthic—pelagic coupling plays a pivotal role in aquatic ecosystems but the effects of fishery driven interactions on its functioning has been largely overlooked. Disentangling the benthic—pelagic links including effects of mixed fisheries, however, needs sketching a whole description of ecosystem interactions using quantitative tools. A holistic food web model has been here developed in order to understand the interplay between the benthic-pelagic coupling and mixed fisheries in a Mediterranean system such as the Strait of Sicily. The reconstruction of the food web required review and integration of a vast set of local and regional biological information from bacteria to large pelagic species that were aggregated into 72 functional groups. Fisheries were described by 18 fleet segments resulting from combination of fishing gears and fishing vessel size. The input-output analysis on the food web of energy pathways allowed identifying effects of biological and fishery components. Results showed that the structure of the Strait of Sicily food web is complex. Similarly to other Mediterranean areas, the food web of the Strait of Sicily encompasses 4.5 trophic levels (TLs) with the highest TLs reached by bluefin tuna, swordfish and large hake and largely impacted by bottom trawling and large longline. Importantly, benthic-pelagic coupling is affected by direct and indirect impacts among groups of species, fleets and fleets-species through the whole trophic spectrum of the food web. Moreover, functional groups able to move on large spatial scales or life history of which is spent between shelf and slope domains play a key role in linking subsystems together and mediate interactions in the Mediterranean mixed fisheries.
... Depletion of oysters in Chesapeake Bay resulted in substantial loss of water filtration capacity linked to reductions in water quality (Newell 1988). These ecosystem changes are further complicated by previously hidden interactions elsewhere in food webs resulting in cascading effects in other taxa (Travis et al. 2013;Eddy et al. 2017). The current prevalence of active gears like trawls can often result in reductions in biomass, diversity, body size and alterations in the trait composition (e.g. ...
... This is surprising, given the global scale of invertebrate fisheries and the expansion of these fisheries in recent decades both in biomass and number of taxa fished (Anderson et al. 2011). These species provide numerous services including water filtration, bioturbation, benthic-pelagic coupling, and creation of hard habitat (Anderson et al. 2011;Eddy et al. 2017). However, many of these traits are associated with increased vulnerability to fisheries: low mobility, surface dwelling, long lifespans, suspension feeding and large body size (Bremner et al. 2003;Dulvy et al. 2003;Cesar and Frid 2009). ...
Article
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A leading argument for no-take marine protected area (marine reserve) establishment is their contribution to the conservation of biodiversity, but the impacts of reserves on ecosystem functioning have seldom been quantified. This is unusual given the value of services provided by ocean ecosystems to human well-being. While no single index can describe ecosystem function, a set of life-history attributes possessed by taxa can be used to infer differences in ecosystem function across space and time. In this study, we use biological trait analysis to determine whether the attributes of invertebrate taxa differ between inside of six no-take marine reserves and outside, in fished areas in the Central Philippines. Using permutational multivariate analyses, we found that the composition of traits and taxa were significantly different between reserve and non-reserve areas. Habitat use, morphology and mobility traits were the biggest contributors to dissimilarity, indicating that reserves can have community-wide effects that change the functional composition of invertebrate assemblages. Notably, traits associated with coral habitat use, bearing a shell, lacking mobility and filter feeding are the most important traits associated with differences in community structure between reserve and non-reserve areas. At the taxa composition level, small shrimps, three families of bivalve, two families of burrowing snails and brittle stars are the most important contributors to differences in taxonomic community composition. The addition of organismal attributes to traditional taxa composition approaches provides richer insight into how ecosystems respond to protection and has the potential to inform practitioners on conserving for ecosystem traits.
... The ecosystem effects of fishing have been widely studied for marine fish and invertebrates, and include the effects of habitat destruction, bycatch, overexploitation and food-web alterations on biodiversity and ecosystem stability (e.g. Jennings and Kaiser 1998, Dayton et al. 2002, Eddy et al. 2017). Studies on the ecosystem consequences of seaweed harvesting are less prominent ( Lorentsen et al. 2010, Stagnol et al. 2013, Krumhansl et al. 2017, Pérez-Matus et al. 2017) but highlight the importance of kelp forests, rockweed beds and other seaweed stands in providing critical ecosystem structure, functions and services. ...
... Implementing an EBM approach to seaweed harvesting would lay a proper foundation for the sustainable use of canopy-forming seaweeds while allowing them to continue to provide essential ecosystem functions and services for the benefit of coastal communities around the world (Table 2). Similarly, implementing EBM into other commercial fisheries can be beneficial for fishers, marine ecosystems and society alike ( Worm et al. 2009, Eddy et al. 2017. As with other management strategies, an EBM approach would require proper governance and regulations, implementation on the ground, as well as monitoring and enforcement to meet goals and targets (Pitcher et al. 2009). ...
Article
Harvesting wild seaweeds has a long history and is still relevant today, even though aquaculture now supplies >96% of global seaweed production. Current wild harvests mostly target canopy-forming kelp, rockweed and red macroalgae that provide important ecosystem roles, including primary production, carbon storage, nutrient cycling, habitat provision, biodiversity and fisheries support. Harvest methods range from selective hand-cutting to bottom trawling. Resulting ecosystem impacts depend on extraction method and scale, ranging from changes in primary production to habitat disruption, fragmentation, food-web alterations and bycatch of non-target species. Current management often aims for sustainable harvesting in a single-species context, although some agencies acknowledge the wider ecosystem structure, functions and services seaweeds provide. We outline potential ecosystem-based management approaches that would help sustain productive and diverse seaweed-based ecosystems. These include maintaining high canopy biomass, recovery potential, habitat structure and connectivity, limiting bycatch and discards, while incorporating seasonal closures and harvest-exclusion zones into spatial management plans. Other sustainability considerations concern monitoring, enforcement and certification standards, a shift to aquaculture, and addressing cumulative human impacts, invasive species and climate change. Our review provides a concise overview on how to define and operationalize ecosystem-based management of seaweed harvesting that can inform ongoing management and conservation efforts.
... Whale recovery can provide a probe of pelagic ecosystem organization, especially because whales can consume up to 62% of the net production of a system [43] and play a crucial role in nutrient cycling [44]. More recently, similar ideas have been explored in an effort to understand the general effects of removing low trophic level species, such as forage fish and invertebrates, on whole ecosystems [45,46]. The classic trophic cascade here is reversed because prey species are exploited and a wide variety of predators are compromised [42,43]. ...
... There is an urgency to such an expanded perspective because an increasingly transnational human enterprise [63] is greatly magnifying our role as a hyperkeystone species [64]. A new perspective on human influence on ecological interaction chains should help to unify diverse studies on changes in complex biological interactions (e.g., top-down trophic cascades [65] or the bottom-up effects of forage fish exploitation [45,46]), modifications to structural environments (e. g., ecosystem engineering [66]), and progressive changes to physical properties (e.g., global warming and ocean acidification [20,28]). This provides a strong argument that ecologists and conservation practitioners need to become increasingly aware of the importance of such connected interaction chains in driving ecological change across all different habitats [10,15,67,68]. ...
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Ecologists have identified numerous keystone species, defined as organisms that have outsized ecological impacts relative to their biomass. Here we identify human beings as a higher-order or ‘hyperkeystone’ species that drives complex interaction chains by affecting other keystone actors across different habitats. Strong indirect effects and a global reach further characterize these interactions and amplify the impacts of human activities on diverse ecosystems, from oceans to forests. We require better understanding of hyperkeystone interaction chains most urgently, especially for marine species and terrestrial large carnivores, which experience relatively higher exploitation rates than other species. This requires innovative approaches that integrate the study of human behavior with food-web theory, and which might provide surprising new insights into the complex ecology of our own species. Recent work highlights the unique ecology of our own species relative to other predators. For example, the median exploitation rates we exert on marine or terrestrial species are up to 15-fold higher than for any other predator. We show that human exploitation as well as other impacts commonly affect known keystone species, driving potentially complex interaction chains that often remain unexplored. We propose that such effects make humans a higher-order or ‘hyperkeystone’ species, which we define as a species that affects multiple other keystone species across habitats. While we focus on humans, it is likely that other far-ranging generalist predators, such as killer whales, could also be considered as hyperkeystone species. Understanding our hyperkeystone role may require innovative approaches that merge observations, experiments, and food-web models, and will bring new insights into how our unique ecology is affecting global patterns of ecological change.
... Marine invertebrates provide a source of high-quality protein, and their fisheries offer important employment and income opportunities (Anderson et al., 2011). Although marine finfish fisheries have declined worldwide, exploitation of invertebrates has increased, with upward trends in catch occurring across many taxonomic groups as opposed to a few major species (Anderson et al., 2011;Eddy et al., 2017;FAO, 2018FAO, , 2019). An increase in marine invertebrates is likely a result of released predation pressure from formerly abundant higher-trophic-level predators (Arkhipkin et al., 2015). ...
... Most invertebrate stocks are spatially heterogenetic and gregarious (Prince and Hilborn, 1998). Diverse marine nektonic invertebrates with short life spans transfer energy to higher trophic levels, and play important roles in ecosystem structure and functioning (Ventura et al., 2000;Bandelj et al., 2009;Dalu et al., 2017;Eddy et al., 2017). Sustainable exploitation of nektonic invertebrates requires an understanding of their communities, distribution, and structure. ...
Article
Although fisheries for invertebrates are increasing rapidly worldwide, many of them lack the rigid assessments and regulations that are typical of finfish fisheries. We report nektonic invertebrate communities of the Yangtze River estuary in the boreal autumn (November) from 2013 to 2017, and report how these are related to environmental variables. Communities comprise 26 macro-invertebrate nektonic species in 11 families, of which 8 species are dominant in abundance and biomass. Significant temporal variation in abundance, biomass, and diversity is apparent. Highest Margalef richness (D), Shannon–Wiener diversity (H’), and Pielou’s evenness (J’) index values occur in 2015, and the lowest occur in 2017. Abundance and biomass peak in 2013 and decline to their lowest values in 2017. Redundancy analysis and analysis of similarities identifies significant spatial and temporal variation in nektonic invertebrate communities to have occurred from 2013 to 2017, attributable to variations in dissolved oxygen, temperature, salinity, total suspended matter, and pH. Significantly different communities occur in the northern and southern waters. Depth, total suspended matter, dissolved oxygen, pH, and total phosphorus significantly affect the distributions of dominant species. An improved understanding of spatial and temporal variation in nektonic invertebrate communities of the Yangtze River estuary facilitates their conservation and resource management.
... In this context, although, invertebrates play key roles in marine ecosystems, they are poorly understood, with reduced stock and ecosystem-impact evaluations. Therefore, enhanced management attention is needed, to avoid negative consequences for ocean ecosystems and human well-being (Anderson et al. 2011;Eddy et al. 2017;Vaughan et al. 2017;Henriksson et al. 2018a,b). ...
Article
Aquaculture is considered the fastest-growing food supply, invertebrates being a key element; in particular, whiteleg shrimp (Litopenaeus vannamei). They contribute to human welfare, albeit potential negative environmental effects should be properly addressed. Indeed, the environmental impact of aquaculture is lower than using wild captures. Therefore, shrimp aquaculture is reviewed in relation to bioremediation and sustainability, from an ecological perspective. Since metagenomics has great potential for aquaculture, an experimental research using biofilms on whiteleg shrimp effluents is also included, as a proof of concept, given the lack of published results. That revealed a great diversity of microbes: Bacteria, Archaea, Viridiplantae, Fungi and Protozoa. They included 972 species, grouped in 638 genera and 221 families. Interestingly, the Basic Local-Alignment Search Tool (BLAST) algorithm, against the National Center for Biotechnology Information (NCBI) databases, identified 12 species (or genera as spp.) involved in nitrification processes, which are relevant from an ecological point of view, using a restrictive threshold of �97%. They included Candidatus nitrosopumilus, Nitratireductor aquibiodomus, Nitratireductor spp., Nitratiruptor spp., Nitriliruptor spp., Nitrosococcus spp., Nitrosomonas aestuarii, Nitrosomonas marina, Nitrosomonas spp., Nitrosopumilus maritimus, Nitrospina spp. and Nitrospira spp. To the best of our knowledge, this is the first report of comprehensive metagenomics on microbiotas of Litopenaeus vannamei effluents. These results have clear implications for such cultures, mainly related to nitrification enhancement, as well as worldwide aquaculture bioremediation and environmental sustainability, in general. That is especially relevant to ameliorate pollution, which is particularly, in the current scenario of climate change and global warming.
... Our results are in line with a previous global analyses of long-term trends in cephalopod abundance, which showed that cephalopods have increased consistently across taxa from 1960s to 2010 (Doubleday et al., 2016). Modeling studies at local and regional levels showed that cephalopods play a strong ecosystem role (Eddy et al., 2017). Squids, for example, are able to benefit from a general increase in fishing pressure, mainly due to predation release, and exhibit quick responses to changes triggered by the environment, and as such, are very sensitive to changes in fishing and climate change . ...
Article
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Considerable effort is being deployed to predict the impacts of climate change and anthropogenic activities on the ocean's biophysical environment, biodiversity, and natural resources to better understand how marine ecosystems and provided services to humans are likely to change and explore alternative pathways and options. We present an updated version of EcoOcean (v2), a spatial-temporal ecosystem modeling complex of the global ocean that spans food-web dynamics from primary producers to top predators. Advancements include an enhanced ability to reproduce spatial-temporal ecosystem dynamics by linking species productivity, distributions, and trophic interactions to the impacts of climate change and worldwide fisheries. The updated modeling platform is used to simulate past and future scenarios of change, where we quantify the impacts of alternative configurations of the ecological model, responses to climate-change scenarios, and the additional impacts of fishing. Climate-change scenarios are obtained from two Earth-System Models (ESMs, GFDL-ESM2M, and IPSL-CMA5-LR) and two contrasting emission pathways (RCPs 2.6 and 8.5) for historical (1950–2005) and future (2006–2100) periods. Standardized ecological indicators and biomasses of selected species groups are used to compare simulations. Results show how future ecological trajectories are sensitive to alternative configurations of EcoOcean, and yield moderate differences when looking at ecological indicators and larger differences for biomasses of species groups. Ecological trajectories are also sensitive to environmental drivers from alternative ESM outputs and RCPs, and show spatial variability and more severe changes when IPSL and RCP 8.5 are used. Under a non-fishing configuration, larger organisms show decreasing trends, while smaller organisms show mixed or increasing results. Fishing intensifies the negative effects predicted by climate change, again stronger under IPSL and RCP 8.5, which results in stronger biomass declines for species already losing under climate change, or dampened positive impacts for those increasing. Several species groups that win under climate change become losers under combined impacts, while only a few (small benthopelagic fish and cephalopods) species are projected to show positive biomass changes under cumulative impacts. EcoOcean v2 can contribute to the quantification of cumulative impact assessments of multiple stressors and of plausible ocean-based solutions to prevent, mitigate and adapt to global change.
... This indicates that various functional groups feed on different trophic levels due to the variability of their diets, suggesting the ecosystem is developing due to the network-like structure of the flows (Odum, 1969). CI and SOI are relevant indicators of ecosystems under stress conditions as both decrease with the level of fishing pressure (Eddy et al., 2017, Heymans et al., 2012, so their monitoring is advisable for determining changes in the ecosystem functioning. ...
Article
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The Galapagos Marine Reserve is one of the largest marine protected areas in the world, hosting a high species diversity and endemism and supporting economically important artisanal fisheries for local people and tourists. To ensure proper management and conservation of species in an ecosystem is necessary to determine the species' contributions to ecosystem functions and organization. We characterized the structure and functioning of the southeastern Galapagos Archipelago shelf ecosystem by building a mass balanced Ecopath model representing the period 2001-2004. The model considered 72 functional groups, emphasizing endemic or threatened species (EoTS), commercial species and seven fishing fleets. Various ecological network analysis indicators were used to determine the status of the ecosystem. Structural and flow-based indices, trophic interactions among groups and keystone species indices were used to determine the ecological role of the species, while fishing pressure indicators were analyzed to determine the sustainability of the fisheries. The results indicate the ecosystem has a middle developing level, is stable and resilient. Marine mammals, sharks, birds and fish with high trophic level (TLs) play roles in maintaining the order of the ecosystem and its resilience. Among these groups highlight several EoTS (e.g., the Galapagos sea lion), and some species of commercial value (e.g., the Galapagos sailfin grouper). EoTS and commercial species are important contributors to the ecosystem structure, but those with a lower TL contribute the most to the energy transfer. These findings suggest that certain commercial species deserve more protection as they contribute in a similar way as EoTS to important ecosystem functions. Contrary to what was expected, the results suggest the fishing activities produce moderate impacts, mainly on fisheries target species, but without significantly affecting the ecosystem functions. However, further studies are recommended to reinforce these findings. This model provides information useful for the design of management strategies that balance the conservation and exploitation of the Galapagos marine resources.
... Given the absence of large colonies in dense populations, red coral cannot exert its former ecological role as a habitat-forming species 17 ; thus, red coral should be considered ecologically extinct. The effects of overexploitation affect not only red coral but also many other species in its habitat 18,19 . The magnitude of the human-caused loss of red coral in the Mediterranean provides strong evidence of the shifting-baseline syndrome ("changing human perceptions of biological systems due to loss of experience about past conditions 20,21 ") for this species in shallow habitats. ...
Article
Full-text available
Overexploitation leads to the ecological extinction of many oceanic species. The depletion of historical abundances of large animals, such as whales and sea turtles, is well known. However, the magnitude of the historical overfishing of exploited invertebrates is unclear. The lack of rigorous baseline data limits the implementation of efficient management and conservation plans in the marine realm. The precious Mediterranean red coral Corallium rubrum has been intensively exploited since antiquity for its use in jewellery. It shows dramatic signs of overexploitation, with no untouched populations known in shallow waters. Here, we report the discovery of an exceptional red coral population from a previously unexplored shallow underwater cave in Corsica (France) harbouring the largest biomass (by more than 100-fold) reported to date in the Mediterranean. Our findings challenge current assumptions on the pristine state of this emblematic species. Our results suggest that, before intense exploitation, red coral lived in relatively high-density populations with a large proportion of centuries-old colonies, even at very shallow depths. We call for the re-evaluation of the baseline for red coral and question the sustainability of the exploitation of a species that is still common but ecologically (functionally) extinct and in a trajectory of further decline.
... Based on mass-balance of trophic interactions among all the functional groups (Panikkar and Khan, 2008), EwE quantifies the energy flow between trophic levels and measures the main ecosystem indices, such as total system throughout (TST), total respiration (TR) and transfer efficiency (TE), to indicate the stability and resilience of an ecosystem (Christensen and Walters, 2004). The EwE model incorporates trophic interactions in an ecosystem and can be used to determine the ecological carrying capacity of aquaculture species in the ecosystem (Jiang and Gibbs, 2005;Byron et al., 2011;Kluger et al., 2016b), evaluate the role of certain species in an ecosystem (Morissete et al., 2006;Wong and Dowd, 2014), and even simulate the trophic-dynamics of an ecosystem under different manage strategies (Warren et al., 2014;Eddy et al., 2017;Kumar et al., 2016). ...
Article
Shellfish aquaculture production in the world, especially in China, has expanded rapidly in recent years. However, understanding of potential impacts of shellfish aquaculture on the trophic structure of ecosystem remains limited. Using an Ecopath with Ecosim model, we compared various shellfish aquaculture intensity scenarios to evaluate impacts of shellfish aquaculture on a semi-closed marine ecosystem, located in Jiaozhou Bay, China. This study showed that the Jiaozhou Bay ecosystem could be strongly impacted by the shellfish aquaculture as illustrated by the ecosystem indices such as total system throughout (TST), Finn’s cycle index (FCI), and System omnivory index (SOI). The existence of shellfish aquaculture program led to shifts of major energy sources of Jiaozhou Bay ecosystem from detritus to phytoplankton. Contribution of phytoplankton to the ecosystem energy flow could drop from 75% to 46% if the current shellfish aquaculture program was removed. Intensive shellfish aquaculture could also improve the transfer efficiency of the ecosystem and simplify the food web. In addition, consumption of phytoplankton by cultured shellfish consisted of 90% of total phytoplankton consumption in this ecosystem, indicating that cultured shellfish could exert strong top-down control on phytoplankton in the Jiaozhou Bay ecosystem. Our results demonstrated that intensive cultured shellfish program shifted Jiaozhou Bay ecosystem from a natural-organism-dominated food web into an aquaculture dominated food web. Given these caveats, cultured shellfish is not only economically efficient, but also ecologically efficient. This study suggests that it is informative and necessary to conduct holistic and integrated ecosystem analyses to improve our understanding of potential impacts of shellfish aquaculture on the ecosystem dynamics.
... Long neglected in comparison to finfish fisheries, overfishing in invertebrate fisheries is widespread and a threat to global food security and ecosystem integrity IOP Conf. [40,41]. The high levels of gleaning in many areas around Sulawesi [9,[42][43][44][45] mean that many species are at risk of undetected overfishing and even extirpation; species may be lost without ever having been recorded at sites where they were once abundant, especially those belonging to the infauna such as many of the taxa recorded in this study. ...
... Trophic levels (Table 3) estimated for benthic invertebrates, fish and seabird functional groups were within the usual range (Eddy et al., 2017) found in coastal/estuarine ecosystems. In the first regime (CM), filter feeders and detritivores dominated the system, with few invertebrates acting as intermediate predators (Gastropods) and vertebrates (fishes and birds) as top predators. ...
Article
Structural and functional changes in a sandy beach ecosystem in the southwestern Atlantic (Barra del Chuy, Uruguay) were assessed by contrasting four Ecopath trophic models and performing temporal dynamic simulations using Ecosim. Each model (1982, 1989, 1996 and 2012) represents a historical period of a clam fishery in which regulatory structure, management tools and resource status varied substantially. The results showed that this land-ocean interface experienced significant changes reflected at the population and ecosystem levels, owing to a combined effect of fishing and climate variability. Most system biomass (excluding phytoplankton and detritus) consisted of benthic invertebrates. Phytoplank-ton increased significantly over time, whereas the biomass of benthic macrofaunal components varied among the periods due to bottom-up processes, mass mortalities of the harvested clams and fishing intensity. Major fishing impacts on the targeted clam and mass mortalities occurred concurrently with low phytoplankton biomass, and clam recovery occurred in the absence of harvesting and increasing primary production. Ecosystem-level attributes (e.g., Total System Throughput, Ascendency) showed considerable temporal fluctuations, which were primarily related to changes in system productivity associated with a climatic shift from a cold phase to a warm phase and increasing onshore winds. An analysis of robustness and order showed an ecosystem state lacking the flexibility to adapt to new perturbations. Dynamic simulations showed the prominent bottom-up role of environmental variability on ecosystem function and structure. Temporal dynamics is conducted by changes in primary production forced mainly by temperature patterns. The concurrent role of climate variations and fishing explained the long-term dynamics of this ecosystem, suggesting that sandy beaches are fragile social-ecological systems whose services are increasingly threatened by long-lasting stressors.
... While the latter three are of direct importance for fisheries, by offering high catches or value per fishing effort ( Airoldi and Beck, 2007;Seitz et al., 2014), the former one is a step required to produce recruits to replenish the fishery ( Beck et al., 2001). Fishing may, however, be challenging for the sustainable management of some coastal EFH, not only as some fishing practices are detrimental to the habitats per se, but also because targeted extraction of species from the general marine ecosystem may indirectly influence the habitats by altering predator-prey interactions ( Hopkins, 2003;Eriksson et al., 2011;Pikitch et al., 2014;Östman et al., 2016;Pommer et al., 2016;Eddy et al., 2017). Despite consensus among scientists on the critical importance of EFH, their role for sustaining fish stocks and communities has received relatively little attention ( Beck et al., 2001;Gillanders et al., 2003;Armstrong and Falk-Petersen, 2008;Sheaves et al., 2015). ...
Article
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Many coastal and offshore fish species are highly dependent on specific habitat types for population maintenance. In the Baltic Sea, shallow productive habitats in the coastal zone such as wetlands, vegetated flads/lagoons and sheltered bays as well as more exposed rocky and sandy areas are utilised by fish across many life history stages including spawning, juvenile development, feeding and migration. Although there is general consensus about the critical importance of these essential fish habitats (EFH) for fish production along the coast, direct quantitative evidence for their specific roles in population growth and maintenance is still scarce. Nevertheless, for some coastal species, indirect evidence exists, and in many cases, sufficient data are also available to carry out further quantitative analyses. As coastal EFH in the Baltic Sea are often found in areas that are highly utilized and valued by humans, they are subjected to many different pressures. While cumulative pressures, such as eutrophication, coastal construction and development, climate change, invasive species and fisheries, impact fish in coastal areas, the conservation coverage for EFH in these areas remains poor. This is mainly due to the fact that historically, fisheries management and nature conservation are not integrated neither in research nor in management in Baltic Sea countries. Setting joint objectives for fisheries management and nature conservation would hence be pivotal for improved protection of EFH in the Baltic Sea. To properly inform management, improvements in the development of monitoring strategies and mapping methodology for EFH are also needed. Stronger international cooperation between Baltic Sea states will facilitate improved management outcomes across ecologically arbitrary boundaries. This is especially important for successful implementation of international agreements and legislative directives such as the Baltic Sea Action Plan, the Marine Strategy Framework Directive, the Habitats Directive, and the Maritime Spatial Planning Directive, but also for improving the communication of information related to coastal EFH among researchers, stakeholders, managers and decision makers. In this paper, efforts are made to characterize coastal EFH in the Baltic Sea, their importance and the threats/pressures they face, as well as their current conservation status, while highlighting knowledge gaps and outlining perspectives for future work in an ecosystem-based management framework.
... Version 6.5), is the predominant ecosystem modelling software used globally. It has been applied in many hundreds of ecosystems over the last 30 years and to a diverse set of topics to do with the functioning, perturbation and management of aquatic ecosystemsfor example: climate change (Alva-Basurto and Arias- Gonzalez, 2014;Christensen et al., 2015;Cornwall and Eddy ,2015;Serpetti et al., 2017;Suprenand and Ainsworth, 2017) ; regime shifts (Heymans and Tomczak, 2016;Ofir et al., 2016); hypoxia (de Mutsert et al., 2016); fishing impacts (Coll et al., 2009a;Coll et al., 2009b;Heymans et al., 2009;Piroddi et al., 2010b;Christensen et al., 2014a;Coll et al., 2016;Geers et al., 2016;Eddy et al., 2017b); single and multi-species fisheries management (Cornwall and Eddy, 2015;Eddy et al., 2017a); ecosystem-based management (Lercari and Arreguin-Sanchez ,2009;Jiang et al., 2017); ecosystem-based fisheries management Alva-Basurto and Arias-Gonzalez, 2014;Bourdaud et al., 2016;Jacobsen et al., 2016;Musinguzi et al., 2017;Sagarese et al., 2017), invasive species (Corrales et al., 2017;Haak et al., 2017;McGill et al., 2017); marine protected areas (Abdou et al., 2016); environmental impact assessment (Port MetroVancouver, 2015;Fretzer, 2016); cumulative impact assessment ; ecological indicator monitoring (Gonzalez et al., 2016;Coll and Steenbeek, 2017); primary productivity (Chaalali et al., 2015;Maldonado et al., 2016); impacts of decommissioning of power plants (Vasslides et al., 2017); oil spill restoration (Okey et al., 1999;Okey and Wright, 2004;Sagarese et al., 2017) and contaminant tracing (Larsen et al., 2016). The spatial expansion of EwE, Ecospace, has several relatively new features that allow for representation of spatial processessuch as influencing the distribution of ecological components based on habitat (environmental) preferencesand linking to external environmental forcing data, such as hydrodynamic transports or temperature and salinity patterns (Steenbeek et al., 2013;Christensen et al., 2014b;Steenbeek et al., 2016). ...
Article
The expanding blue economy means the oil and gas industry is just one of many activities in marine and coastal ecosystems. The future management of ecosystems such as the Great Australian Bight (GAB) should be based on a sound knowledge of the physical, ecological, economic and social interactions among the human and natural system components. The Great Australian Bight Research Program (GABRP) has generated extensive new knowledge about the GAB system, making it one of the most well understood deep-water Australian ecosystems. It is a complicated system, with novel and newly recognised ecosystem pathways. A set of system models have been developed to help navigate this complexity, to integrate the new information and establish improved understanding of system processes and the implications of any activities in the region – including monitoring and management.
... The effect of trawl fishing on the marine ecosystems and biodiversity has come under increasing scrutiny during recent years (Jennings and Kaiser, 1998;Rizkalla and Ragheb, 2016;Eddy et al., 2017;Thomas et al., 2017). The most imminent threat to the world's remaining fish stocks is the indiscriminate harvesting of non-target species, typically referred to as 'bycatch' (Pauly et al., 2002) which creates conservation problem when endangered, Mannar, Gulf of Kutch, Islands of Lakshadweep, Andaman and Nicobar, coastal lakes of Pulicat and Chilka and coastal habitats of Mumbai, Ratnagiri, Goa, Karwar, Varkala, Vizhinjam, and Visakhapatnam (Chennubhotla et al., 1987(Chennubhotla et al., , 1990(Chennubhotla et al., , 1991. ...
Article
Baseline information about the quantitative aspects of the marine plant biota dislodged and discarded during the trawl fishery is not available in the literature. An attempt was made to document the diversity and biomass of plant biota (seaweeds and seagrasses) destroyed and discarded during the trawl operations along the Tuticorin (renamed as Thoothukudi), Southeast coast of India. Fifteen species of seaweeds and three species of seagrasses were recorded during the study period. The biomass of plant biota discarded was 5 to 50 kg/haul/h during the study period, and the average discard was higher (44.4%) in the pre-monsoon season. The biomass dislodged mainly constituted the seagrasses (63.0%) whereas seaweeds contributed to the extent of 37.0 % of the total biomass. The variation in the values of the biomass of seaweeds and seagrasses shows no statistically significant difference (p-value >0.05) between the seasons. Among the seaweeds, Solieria robusta was most severely damaged species (9 kg/haul/h) whereas the seagrass Cymodocea serrulata was destroyed to the extent of 30 kg/haul/h. In the context of growing environmental and ecological significance of the marine plant biota for ecological balance and fisheries, this report will contribute in delineating effective policies and framework for sustainable fisheries, giving due importance to the conservation of marine flora.
... Consequently, ecosystembased approaches tend to recommend the adoption of strategies to avoid or minimize the impacts of fishing on a diverse portfolio of ecosystem goods and services. These strategies can include controls on the exploitation of forage species to account for the needs of dependent predators [80,35,90], rules to limit non-target mortality and bycatch [75,74], and creation of marine protected areas to protect critical habitats [52,61]. However, progress has been slow [77] as broad support for the general notion of ecosystem-based management [6,64] masks opposition to specific policies such as marine protected areas, fisheries closures, and reductions in catch limits that give rise to trade-offs among different actors, activities or objectives [12,4,14]. ...
Article
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Fisheries can have significant impacts on the structure and function of marine ecosystems, including impacts on habitats and non-target species. As a result, management agencies face growing calls to account for the ecosystem impacts of fishing, while navigating the political and economic interests of diverse stakeholders. This paper assesses the impacts of two specific factors on the attitudes and well-being of shrimp fishers in the context of a selective fisheries closure designed to protect crabs in the Northern Peninsula of Newfoundland and Labrador, Canada: (1) the species portfolios of fishers; and (2) democratic rulemaking. The results of this analysis suggest that shrimp fishers were more likely to support selective closures for the shrimp fishery if they also fished for crab, and felt they had an influence on the management of the fishery. The results further indicate that species portfolio diversification had a positive and statistically significant impact on the subjective economic well-being of fishers. This study contributes to an emerging literature on the human dimensions of ecosystem-based fisheries management, highlighting opportunities to address trade-offs in fisheries through species diversification and by enhancing the role and influence of fishers in management processes.
... Consequently, ecosystembased approaches tend to recommend the adoption of strategies to avoid or minimize the impacts of fishing on a diverse portfolio of ecosystem goods and services. These strategies can include controls on the exploitation of forage species to account for the needs of dependent predators [80,35,90], rules to limit non-target mortality and bycatch [75,74], and creation of marine protected areas to protect critical habitats [52,61]. However, progress has been slow [77] as broad support for the general notion of ecosystem-based management [6,64] masks opposition to specific policies such as marine protected areas, fisheries closures, and reductions in catch limits that give rise to trade-offs among different actors, activities or objectives [12,4,14]. ...
Preprint
Fisheries can have significant impacts on the structure and function of marine ecosystems, including impacts on habitats and non-target species. As a result, management agencies face growing calls to account for the ecosystem impacts of fishing, while navigating the political and economic interests of diverse stakeholders. This paper assesses the impacts of two specific factors on the attitudes and well-being of shrimp fishers in the context of a selective fisheries closure designed to protect crabs in the Northern Peninsula of Newfoundland and Labrador, Canada: (1) the species portfolios of fishers; and (2) democratic rulemaking. The results of this analysis suggest that shrimp fishers were more likely to support selective closures for the shrimp fishery if they also fished for crab, and felt they had an influence on the management of the fishery. The results further indicate that species portfolio diversification had a positive and statistically significant impact on the subjective economic well-being of fishers. This study contributes to an emerging literature on the human dimensions of ecosystem based fisheries management, highlighting opportunities to address trade-offs in fisheries through species diversification and by enhancing the role and influence of fishers in management processes.
... Increasing demand for sea urchin roe in recent decades has led to an extensive overexploitation of natural sea urchin populations. A global decline of 16% in fishery catch was measured between 1995 and 2000 (Anderson et al., 2011;Andrew et al., 2002;Eddy et al., 2017;Robinson, 2004), which in turn led to increasing awareness of the importance of developing sea urchin farming (Robinson, 2004;Robinson et al., 2002). Better understanding of the unique physiology and life history strategy of this taxonomic group is required (Lawrence, 1987;Lawrence and Lane, 1982;Siikavuopio et al., 2006) in order to ensure commercially viable yields. ...
Article
Energy budget and resource distribution were evaluated for the sea urchin Paracentrotus lividus from the Eastern Mediterranean, reared in relatively low (20–22 °C) and high (24–26 °C) temperature regimes. Energy expenditure was quantified for the processes of respiration, excretion, growth and reproduction, as well as the amount and energetic content of the food consumed and its absorption rates. Unfed sea urchins were used to calculate basal energy requirements. A significant trade-off was found between the physiological parameters in response to the different water temperature regimes. In particular, a give-and-take between consumption and absorption rates was observed. Low consumption and high absorption took place in the cold-water treatment, while lower absorption rates in the warmer treatment were compensated for by higher consumption. Energy surplus was distributed through different channels. Investment in growth was significantly more prominent in colder water, whereas in the warm-water treatment investment in reproduction was higher. Total energy expenditure on activity significantly increased with higher water temperature, with a difference of ~40% between the coldest and warmest temperatures; however, expenditure above basal requirements was similar at both temperature levels. Our results show that P. lividus reared in the colder range of temperatures had a more efficient energy expenditure ratio, resulting in a higher (by ~10%) scope for growth than in warmer water. This study confirms the importance of water temperatures as the driver of natural ontogenetic processes in this species. Our data has great relevance for the farming of P. lividus.
... Leeuwin (Hesp et al., 2008). The rapid growth rates of octopus command voracious feeding regimes, and thus their predatory impact on benthic communities can be significant (Boyle & Rodhouse, 2005;Eddy et al., 2017). While octopus adapt rapidly to new environments (Rigby & Sakurai, 2005), they are vulnerable to predation from teleosts, particularly at smaller sizes (Aronson, 1991;Mather & O'Dor, 1991). ...
Article
Full-text available
This study examined the occurrence of octopus across an abalone, Haliotis laevigata, Donovan, sea ranch in south‐western Australia, to understand how octopus may be impacting abalone production. Commercial divers removed 654 octopus and 17,666 empty abalone shells during regular, 2 to 4‐weekly surveys over 27 months. A negative binomial generalised linear model estimated a 78% increase in empty shells per artificial abalone habitat per day, when octopuses were present, after adjusting for location and season. Of the 408 shells examined for evidence of predation, 19% had a small, slightly ovoid hole consistent with those made by octopus. The mean (± 1 SE) length of shells with boreholes (70.3 ± 2.2 mm) was significantly longer than those without (59.8 ± 0.5 mm), and boreholes were concentrated over the adductor, respiratory organs and heart. This study provides important insights into the adaptable feeding regimes of octopus and their potential to impose strong top‐down controls on sea ranching operations.
... 15) have rapidly expanded globally to more than 10 million tons annually and contribute significantly to global seafood provision, export, trade and local livelihoods. On average, 90 per cent of invertebrate catch can be achieved at a 25 per cent depletion rate, requiring less fishing effort, thereby raising profits, while strongly reducing impacts on other trophic groups(Eddy and others, 2017). • The harvesting of scallops (Chlamys islandica) in the Arctic (Barents Sea)(Nosova and others, 2018) and of sea cucumbers, scallops and crabs in the eastern seas of www.invasivesnet.org/news.Available at: www.dfo-mpo.gc.ca/species-especes/ais-eae/about-sur/index-eng.html. ...
... rufiremus and Callinectes ornatus), contributed more than half (66.70% of the individuals) of all the bycatch. In general, portunids are predators (Mantelatto & Christofoletti 2001, Reigada & Negreiros-Fransozo 2001, while shrimp are detritivores and omnivores (Willems et al. 2016), and both are highly generalist (Eddy et al. 2017). These species' predominance is consistent with the paradigm of generalists' dominance in disturbed environments (Ramsay et al. 1998). ...
Article
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Shrimp trawl fisheries constitute a major threat to continental shelves' biodiversity, given their profound impact on benthic communities. We investigated the composition of an invertebrate assemblage impacted by this type of fishery and possible correlations of the abundance and richness with specific environmental parameters. The activities of the industrial shrimp fleet on the north coast of Brazil were monitored over two years. We analyzed 20,303 specimens belonging to seven phyla (Porifera, Cnidaria, Mollusca, Sipuncula, Annelida, Arthropoda, Echinodermata) and 154 species. There was a predominance of generalist and rare species, given that most species (86) were sporadic. Taxonomic composition patterns were complex, dynamic, and were correlated mainly with the temperature and depth of the Amazon continental shelf, the largest in extension and low depth of the South Atlantic. The crustaceans were dominant in both abundance and taxonomic richness. The influence of environmental factors on the abundance of the main species is discussed. The invertebrates are a neglected component in studies of fisheries impact and important components of the ecological structure of the Amazon coast. They are an essential group for developing a holistic fisheries management approach, which will support the sustainability of the region's fisheries and preserve local aquatic communities.
... Invertebrate fisheries are often characterized as "data deficient" due to the relative lack of research and management attention within these fisheries compared to finfish fisheries (Anderson, Flemming, Watson, & Lotze, 2011). This disparity has resulted in a lower level of understanding of invertebrate species' biology and stock dynamics, as well as the broader ecological impacts of these fisheries (Eddy et al., 2016). Within our dataset, these fisheries had the highest The MSC recognizes that many fisheries have limited quantitative information available with which to assess performance. ...
Article
Fishery improvement projects (FIPs) are emerging as a popular market‐based means to improve fisheries sustainability and have been employed in scores of fisheries around the world; however, project ability to realize improvements has been highly variable, and little is known about how fishery and project conditions affect improvement efforts. In order to evaluate the effectiveness of the FIP model as a tool for improving diverse fisheries around the world, we compile a unique dataset of social, ecological and economic characteristics for over 60 FIPs globally, which we use to identify key attributes correlated with improvements in fishing practices, management and/or on‐the‐water outcomes. Using a random forest classifier, we identify three important attributes related to FIP effectiveness in demonstrating improvements. Specifically, FIPs are more likely to have achieved improvements with increased cumulative project time, when regional‐level management arrangements are present and when the target species has a moderate inherent vulnerability to fishing. Interestingly, improvements were not correlated with a number of expected features, including a fishery's socio‐economic setting or baseline performance against the desired sustainability standard (e.g. the Marine Stewardship Council fisheries standard). This study improves our understanding of factors related to FIP effectiveness in improving fisheries practices and management and provides key insights for practitioners into important attributes to consider when implementing the FIP model to promote fisheries sustainability.
... By their activities, they provide and transform habitats and improve the water quality for other species. Their catch continues to increase and can be gravely affected by bottom trawling and seafood disturbance [1]. In the Northern Adriatic, Mediterranean scallop (Pecten jacobaeus L.) and tuberculate abalone (green ormer) (Haliotis tuberculata L.) are particularly threatened by such activities. ...
Article
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In the shallow Northern Adriatic, marine mollusks are affected by bottom trawling and seafood disturbance. Seasonal oscillations of oceanographic factors additionally influence their physiology, stress responses and survival. Tissue responses to seasonal variations in green ormer (Haliotis tuberculata L.) and Mediterranean scallop (Pecten jacobaeus L.) in the Northern Adriatic have not been reported. Hence, their biochemical and antioxidant defense properties over seasons were studied and the microanatomical structure of their tissue was correlated with function. Histological analysis of gonads revealed two peaks of gonadal maturation and spawning during the spring/summer period and winter season for scallops, and one peak during the fall for ormers. The gonadal maturation of both species was correlated with their seasonal variations of metabolic demands and antioxidant capacity. The lipid vacuoles of tubuloacinar terminations in the digestive gland differed between the two species; in scallop they are several-fold larger in size and number. Low temperatures in winter contributed to a decline in enzymatic antioxidant defense in scallop tissues, having lower superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity, and higher concentrations of thiobarbituric acid reactive substances (TBARS) and total antioxidant status (TAS). In ormers, winter induced lower TAS, TBARS, SOD and GPx concentrations. The significant difference of winter TAS and TBARS levels between ormers and scallops was correlated with variations in their reproductive cycles, as well as in antioxidant defense systems. The most important factor for stress-related parameters for both species in this work was found to be the season-induced temperature change.
... declines of invertebrate populations may have significant trophic effects on wider marine ecosystems (Eddy et al. 2017). ...
Thesis
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Coral reef ecosystems around the world are declining as a result of human impacts including overfishing, pollution and climate change. The coral reefs of South Sinai are significant because of their unique biodiversity, the income that they generate for Egypt through diving tourism and their importance as traditional fishing grounds for the Mzeina Bedu. This PhD takes a multidisciplinary approach to evaluate the status of coral reefs in South Sinai, with particular emphasis on Bedouin fishers and their fisheries. In Chapter 1, I examine the importance of culture and traditional knowledge in the successful management of coral reefs and natural resources in general. In Chapter 2, I focus on the Bedouin tribes of South Sinai to understand their history and socioeconomic status; investigating their fishing techniques and sites as well as their traditional understanding of coral reef biodiversity and ecology. Chapter 3 focusses on the ecological status of finfish populations at sites along the South Sinai coastline, evaluating the status of stocks and potential Bedouin fishery impacts. Chapter 4 examines the invertebrate fishery, which is mainly practised by Bedouin women and targets Tridacna clams. Chapter 5 takes a fishery-dependent approach to assess the catch of Bedouin fishers, to understand important biological and socioeconomic parameters that influence the fishery. In Chapter 6, I use statistical modelling techniques on long-term coral reef ecosystem data sets from the study area to analyse longer-term trends in the ecological status of reefs in South Sinai and likely causes for these trends. Coral reefs provide income, tourism, food and coastal protection to local communities and indigenous people throughout the tropics. The socio-cultural facets of the Mzeina Bedu have been inextricably connected to the reefs and associated fisheries of South Sinai for generations. However, exploited finfish and invertebrate communities have declined in both size and abundance with increased fishing pressure, resulting in ecosystem-wide impacts. The Mzeina themselves should be integral to any proposed fisheries monitoring or management initiatives, and technological approaches may provide useful cost-effective tools. Fisheries ecosystem-level declines have been apparent over at least the last decade and sustained monitoring is essential to ensure that the impact of management initiatives may be measured. If urgent collaborative management and enforcement actions are implemented alongside a programme to develop livelihood opportunities for the Mzeina, the reefs of South Sinai could return to a state that supports both the socioeconomic needs of the Bedu and continues to generate substantial tourism income.
... In the last decade, however, there has been a considerable increase in research on MNP as an important source of stress for other marine animals, such as many species of fish and invertebrates capable of producing and detecting sounds (Tolimieri et al., 2000(Tolimieri et al., , 2004Popper et al., 2001;Montgomery et al., 2002;Amorim, 2006;Hu et al., 2009;Patek et al., 2009;Holt and Johnston, 2011;Williams et al., 2015;Ladich, 2019). Understanding the impact of MNP on fish and invertebrates is crucial because both these groups include species that are threatened or have a significant socio-economic importance, e.g. for fisheries and aquaculture (Holmlund and Hammer, 1999;Anderson et al., 2011;Eddy et al., 2017). In addition, many species of invertebrates and fish play key roles: 1) some species occupy, within food webs, a range of trophic positions from primary consumers to apex predators, in some cases as keystone predators (e.g. ...
Article
Marine noise pollution (MNP) can cause a multitude of impacts on many organisms, but information is often scattered and general outcomes difficult to assess. We have reviewed the literature on MNP impacts on Mediterranean fish and invertebrates. Both chronic and acute MNP produced by various human activities - e.g. maritime traffic, pile driving, air guns - were found to cause detectable effects on intra-specific communication, vital processes, physiology, behavioral patterns, health status and survival. These effects on individuals can extend to inducing population- and ecosystem-wide alterations, especially when MNP impacts functionally important species, such as keystone predators and habitat forming species. Curbing the threats of MNP in the Mediterranean Sea is a challenging task, but a variety of measures could be adopted to mitigate MNP impacts. Successful measures will require more accurate information on impacts and that effective management of MNP really becomes a priority in the policy makers' agenda.
... Ecosystem-based fishery management (EBFM) is advocated to avoid irreversible ecological degradation and rebuild fishery resources (Patrick and Link, 2015;Eddy et al., 2017). Admittedly, the implementation of EBFM is still impeded in many developing countries due to inadequate data for running ecosystem models (Hamel and Bryant, 2017). ...
Article
Seasonal fishing closures are often used in fisheries management to conserve overfished stocks. As one of the unintended consequences, fishermen often contend for maximizing catches immediately after reopening fisheries. The resultant large catch landings in a short time period (i.e., pulse fishing) may undermine the benefit of closure. We implemented an end-to-end model OSMOSE-JZB (Object-oriented Simulator of Marine ecOSystem Exploitation OSMOSE) modelling ecosystem in the Jiaozhou Bay located in China to evaluate the impact of pulse fishing on the effectiveness of seasonal closure at levels of fish community, population, and individual. Our study demonstrated that the three-month closure was successful in conserving fish stocks. There were small variations on ecological indicators (i.e., total biomass of the community, mean trophic level of the community, mean trophic level of the catch, and Shannon-Wiener biodiversity index) when pulse fishing occurred. Pulse fishing seemed not to result in a great shift in community structure. Compared to other species, the biomass of two large predatory fishes were more susceptible to pulse fishing. Pulse fishing could change the pressure of predators to fish stocks via food webs, especially for young individuals. Our simulations indicate that we can improve the effectiveness of seasonal closure by managing pulse fishing. Although the results derived in this study may be specific to the target ecosystem, the general approach is applicable to other ecosystems when evaluating fishing impacts.
... The ecosystem effects of trawling can range from changes in the functioning of marine sediments , to bottom-up interactions with higher trophic levels (Eddy et al., 2017;. The results of this study provide additional evidence that chronic trawling has a strong negative effect on the abundance (i.e. ...
Thesis
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The aim was to examine which characteristics of benthic communities are most sensitive to bottom trawling. This was done using two intensive trawl fisheries in Denmark as case studies; shellfish dredging in shallow coastal waters, and otter trawling for Norway lobster in the Kattegat. Detailed benthic sampling programmes were undertaken to survey and analyse the response of benthic communities along spatially accurate gradients of trawling intensity. A particular focus was to develop and test a range of benthic indicators. The results are presented in three research papers, which form the basis of the thesis.
... In the current thesis the term EAF will be used and applied throughout the thesis. In EAF, fisheries are considered in a perspective of the wider ecosystem in which they operate (Eddy et al. 2017). The target species is an integral part of the ecosystem, and thus impacting a target species also has effects on the entire ecosystem. ...
... We acknowledge the complexity of the combination of the fac- (Anderson et al., 2008;Cury et al., 2008;Cushing, 1990Cushing, , 1995Eddy et al., 2017;Essington et al., 2015;Jackson et al., 2001;Jennings & Kaiser, 1998;Hsieh et al., 2006;Hutchings & Reynolds, 2004;Reno, 1998;Shelton & Mangel, 2011;Smith, 1994). ...
Article
The increasing need to account for the many factors that influence fish population dynamics, particularly those external to the population, has led to repeated calls for an ecosystem approach to fisheries management (EAFM). Yet systematically and clearly addressing these factors, and hence implementing EAFM, has suffered from a lack of clear operational guidance. Here, we propose 13 main factors (shift in location, migration route or timing, overfishing (three types), decrease in physiology, increase in predation, increase in competition, decrease in prey availability, increase in disease or parasites and a decline in habitat quality or habitat quantity) that can negatively influence fish populations via mechanisms readily observable in ~20 population features. Using these features as part of a diagnostic framework, we develop flow charts that link probable mechanism(s) underlying population change to the most judicious management actions. We then apply the framework for example case studies that have well‐known and documented population dynamics. To our knowledge, this is the first attempt to provide a clearly defined matrix of all the probable responses to the most common factors influencing fish populations, and to examine possible diagnostics simultaneously, comparatively and relatively in an attempt to elucidate the most probable mechanisms responsible. The framework we propose aims to operationalize EAFM, thereby not only better diagnosing factors influencing fish populations, but also suggesting the most appropriate management interventions, and ultimately leading to improved fisheries. We assert the framework proposed should result in both better use of limited analytical and observational resources and more tailored and effective management actions.
... The ecosystem effects of trawling can range from changes in the functioning of marine sediments (Sciberras et al., 2016), to bottom-up interactions with higher trophic levels (Eddy et al., 2017;Hiddink et al., 2011;Hinz et al., 2017). The results of this study provide additional evidence that chronic trawling has a strong negative effect on the abundance (i.e. ...
Article
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Bottom trawling alters the abundance, diversity, size-composition, and function of benthic communities. However, the ability to detect these impacts over large spatial scales can be obscured by various complicating factors, such as community adaptation to disturbance and co-varying environmental conditions. An ecosystem-based approach to fisheries management therefore requires ecological indicators which can ‘disentangle’ trawling effects from other natural and human drivers, and respond effectively to shifts in ecological quality. We collected benthic macrofaunal samples at 21 sites across a Norway lobster Nephrops norvegicus fishing ground in the Kattegat, and separated the benthic community into small (1-4mm) and large (>4mm) size fractions. Four taxonomic indicators (total density, species density, Shannon diversity, and biomass) and four functional indicators (functional diversity, functional richness, functional evenness, and functional dispersion) were calculated based on each size fraction, and the two fractions combined (pooled community). Here, we compare the ability of these indicators to detect trawling impacts across size categories. We show that indicators derived from large macrofauna were highly effective in this regard, and were less influenced by other environmental drivers, such as depth, sediment grain size, bottom current velocity, salinity, and temperature. This suggests that the taxonomic and functional characteristics of benthic communities display a size-dependent sensitivity to trawling disturbance, and therefore community metrics based on large benthic macrofauna may provide useful indicators. By contrast, indicators derived from the small fraction performed poorly, and those based on the pooled community demonstrated a varied ability to detect trawling. Small macrofauna are typically characterised by high density, diversity, and population growth rates, and their relative resilience to trawling may mask the response of the more sensitive macrofauna. This highlights an underlying issue with calculating indicators based on the whole benthic community. The approach outline here is easily applied, improves indicator performance, and has the potential to reduce laboratory workloads due to the fewer taxa and individuals required for analyses.
... EWE allows the description of food webs and their interactions, the simulation of overfishing scenarios (Wang et al. 2016), and description and analyses of the flow of food webs (Odum 1969, Coll et al. 2006. EwE also makes it possible to simulate the trophic dynamics of an ecosystem under different management strategies (Eddy et al. 2017, Kumar et al. 2016. Recently, EWE is being used to study the effects of ocean warming (Bentley et al. 2017, invasive species (Corrales et al. 2017), and pollutants (Tierney et al. 2018, Walters and. ...
Article
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The Moroccan Atlantic coast is considered as one of the richest fishing areas in the world, having rich biodiversity, and supporting the fisheries sector. However, studies have shown that the ecosystem presently suffers from overexploitation of fishery resources and environmental degradation. To quantify these impacts, the characterization of the ecosystem is essential. In this work, an Ecopath model (EwE), which assumes steady-state and mass-balanced conditions for the Moroccan Atlantic coast ecosystem, was developed and balanced. Network analysis included in the Ecopath software package was used to estimate trophic interactions and the maturity of the ecosystem. The model consisted of 29 functional groups. The results showed a Total System Throughput (TST) which is comprised mainly of flows into detritus, followed by export, consumption, and respiration. Systemic indicators, suggest that the Moroccan Atlantic coast is an immature and developing ecosystem. Further observations on the functioning and dynamics of the ecosystem are discussed.
... Among the different ecosystem model platforms used today, Ecopath with Ecosim (EwE) is a freely available tool to describe and parameterize the structure and functioning of aquatic ecosystem (Polovina, 1984;Christensen and Pauly, 1992). EwE has become an increasingly accepted tool to quantify system status with selected indicators (Christensen, 1995;Reed et al., 2017), to compare the similarities and differences between various ecosystems (Hattab et al., 2013;Lassalle et al., 2013;Heymans et al., 2014;Ju et al., 2020b), to assess the impacts of environmental and anthropogenic disturbances (Ainsworth et al., 2011;Guénette et al., 2014;Ocampo Reinaldo et al., 2016;Eddy et al., 2017), and to play a key role in ecosystem management (Rochet and Trenkel, 2003;Rochet et al., 2010;Lassalle et al., 2011). However, to date, no EwE model has been developed for the STWS. ...
Article
A first mass balance food web model was developed to parameterize and characterize the structure and functioning of the upwelling ecosystem in the Southern Taiwan Strait (STWS). The model representing the ecosystem state and trophic flows in 2001 includes 50 functional groups from primary producers to marine mammal and 6 fishing fleets. The basic outputs and trophic flows in the ecosystem are analyzed using ecological indicators. Results indicate that phytoplankton, zooplankton, benthos and shrimps are structuring groups while dolphins, top predatory fishes, seabirds, lizard fish, hairtail and mantis shrimps are the keystone groups within the ecosystem. Based on the maturity indicators, STWS is at a mature state. An analysis of control mechanisms indicates that the top-down effect was the primary ecosystem control mechanism, although bottom-up effects were also in play. In addition, fishing impacts were analyzed throughout the food web. Such modelling of the structure and functioning of ecosystem provides basic information for stakeholders and policy-makers to implement ecosystem-based management.
... RLs are ecologically important in NZ and southern Australia and are considered to be a keystone species in temperate reef communities, playing an important role in trophic cascades [9,26,[41][42][43], as well as in structuring soft sediment communities [44]. From an economic perspective, RLs are the most important invertebrate targeted for commercial and recreational fishing, supporting large fisheries in Australia and NZ [9,37,38,45]. ...
Article
Full no-take marine reserves (MRs) act as tools for biodiversity protection that reduce or remove human-induced disturbances and support the recovery of harvested species. Even if not designed specifically for fisheries management, MRs have the potential to enhance locally and distantly fished populations. This study quantified contemporary catch per unit effort (CPUE) of rock lobsters (RLs) with respect to weight and abundance inside and outside two central New Zealand MRs (Kapiti MR established in 1992, Taputeranga MR established in 2008) using commercial fishing methods (pots), and compared it to historical CPUE data. On average, mean CPUE and mean RL size were significantly greater inside than outside at both MRs. Contemporary CPUE at both MRs was approximately twice that of historical CPUE prior to the reserves being established. At Taputeranga, but not at Kapiti MR, we observed a gradient in CPUE with distance from the centre of the reserve. MRs had higher CPUE at reefs that were fully protected (entire reef in the MR) than at partially protected reefs (reef spans the MR boundary), which in turn had higher CPUE than unprotected reefs (entire reef outside the MR). Our results indicate that RL populations are responding positively to protection, but that factors such as the amount of reef area protected and proximity to reserve boundary contribute differently to RL responses. Our findings contribute to the design of MRs with respect to the habitat they protect and to a better understanding of the interactions between MRs and local fisheries.
... Fishes represent a highly diverse group and may play a key role in ecosystem processes, such as decomposition and productivity of aquatic ecosystems (McIntyre et al., 2007;Jennings and Wilson, 2009;Eddy et al., 2017;Benkwitt et al., 2020). When introduced into a new environment, non-native fishes may change ecosystem functioning directly by: (i) causing bioturbation, increasing organic matter resuspension (Junior et al., 2018); (ii) providing carcasses and feces and increasing nutrient release (Boros et al., 2015); (iii) translocating nutrients among lake compartments (from sediment to water, from the littoral to the pelagic or vice versa); or indirectly by (i) decreasing native species populations (via competition or predation) (Cucherousset andOlden, 2011, Ricciardi et al., 2013), and (ii) having top-down effects, which may favor algal growth (Campos-Silva et al., 2020). ...
Article
Non-native species are considered a major global threat to biodiversity, and their expansion to new ecosystems has recently increased. However, the effect of non-native species on ecosystem functioning is poorly understood, especially in hyperdiverse tropical ecosystems where long-term studies are scarce. We analyzed the relationship between richness, biomass, and β-diversity of non-native and native fishes during 16 years in five hyperdiverse tropical shallow lakes. We further elucidated how an observed increase in the proportion of richness, biomass, and β-diversity of non-native over native fishes affect crucial multifunctional processes of lakes (decomposition and productivity). We found a general positive relationship between the richness and biomass of non-native and native fishes. However, the slope of this relationship decreased continuously with time, displaying an increase in non-native species richness and a decrease in native species richness over time. We also detected a negative relationship between the β-diversity of non-native and native fishes over time. Moreover, the increase in the non-native:native ratio of species richness, biomass, and β-diversity over time decreased ecosystem multifunctionality. Our results suggest that non-native fishes caused a homogenization of the native fish species over time, resulting in impoverishment of ecosystem multifunctionality.. Therefore, focus on long-term effects and use of multiple biodiversity facets (α- and β-diversity) are crucial to make reliable predictions of the effects of non-native fish species on native fishes and ecosystem functioning.
... Their ability to "hear", by perceiving the particle motion component of sound, has long been ignored. Given that invertebrates constitute approximately 60% of eukaryotic marine species (Ausubel et al., 2010), play pivotal roles in marine ecosystems (Glynn and Enochs, 2011;Queirós et al., 2013) and are growing in commercial importance (Eddy et al., 2017;Fisheries F A O, 2016), there is an urgent need for more in depth studies, as highlighted in reports by the Convention of Biological Diversity (CBD, 2012) and OSPAR (Götz et al., 2009) on the impacts of noise on invertebrates in the marine environment. ...
Article
Responses of marine invertebrates to anthropogenic noise are insufficiently known, impeding our understanding of ecosystemic impacts of noise and the development of mitigation strategies. We show that the blue mussel, Mytilus edulis, is negatively affected by ship-noise playbacks across different levels of biological organization. We take a novel mechanistic multi-method approach testing and employing established ecotoxicological techniques (i.e. Comet Assay and oxidative stress tests) in combination with behavioral and physiological biomarkers. We evidence, for the first time in marine species, noise-induced changes in DNA integrity (six-fold higher DNA single strand-breaks in haemocytes and gill epithelial cells) and oxidative stress (68% increased TBARS in gill cells). We further identify physiological and behavioral changes (12% reduced oxygen consumption, 60% increase in valve gape, 84% reduced filtration rate) in noise-exposed mussels. By employing established ecotoxicological techniques we highlight impacts not only on the organismal level, but also on ecological performance. When investigating species that produce little visually obvious responses to anthropogenic noise, the above mentioned endpoints are key to revealing sublethal effects of noise and thus enable a better understanding of how this emerging, but often overlooked stressor, affects animals without complex behaviors. Our integrated approach to noise research can be used as a model for other invertebrate species and faunal groups, and inform the development of effective methods for assessing and monitoring noise impacts. Given the observed negative effects, noise should be considered a potential confounding factor in studies involving other stressors.
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Crustaceans were among the most valuable fishery resources in Hong Kong. However, the unrestricted and intensive use of different fishing gears, especially bottom trawling, has led to the depletion of commercially important crustaceans in Hong Kong since the 1980s. This study investigated whether commercial crustaceans recovered after the implementation of a permanent Hong Kong-wide trawl ban that began on December 31, 2012. Standardized field surveys were conducted using a commercial shrimp trawler at two sites in eastern and western waters of Hong Kong before (2004) and after the trawl ban (2013–2014 and 2015–2016) and two sites in southern waters after the trawl ban. Diversity, mean size, abundance, biomass and level of disturbance of commercial crustaceans from the three periods were investigated. The eastern waters exhibited an increased diversity of crustacean assemblages in Inner Tolo, and a higher abundance and biomass of crabs were detected in Outer Tolo after the trawl ban. Reduced disturbance, higher diversity in crustacean assemblages and greater abundance and biomass of predatory crabs were observed after the trawl ban in the outer estuary of western waters, and increased abundance and biomass of shrimp were detected in the inner estuary of western waters. No temporal or negative changes were detected in the southeast and southern waters of Lamma Island. The various responses of crustacean assemblages in Hong Kong waters revealed the critical role of complex interactions among multiple stresses, such as ongoing reclamation works, illegal trawling activities and increased fishing efforts using other (legal) fishing methods.
Article
Fish diets play a critical role in our understanding of aquatic trophic dynamics and are an important component in developing ecosystem-based approaches to fisheries management. Although large nektonic fishes exert top-down predator effects on the food web and typically support viable commercial and recreational fisheries, little is known about the diet of this guild. We evaluated the diets (6327 stomachs) of four nektonic predatory fishes (Pomatomus saltatrix [78–395 mm], Cynoscion regalis [91–520 mm], Morone americana [156–361 mm], and Morone saxatilis [82–785 mm]) in Delaware Bay and in the adjacent ocean. To assess ontogenetic, geographic, and interspecific variation in diets, observations from individual fish stomachs were clustered into species-size class groups, and dietary overlap was estimated using multivariate analyses. A shift in diet composition, as well as diversity, occurred along the estuarine gradient and into the adjacent ocean. Some prey were shared by most predators, including some crustaceans (dominated by Callinectes sapidus, mysids, and Palaemonetes spp.), fundulids (dominated by Fundulus heteroclitus), engraulids (dominated by Anchoa mitchilli), and clupeids (dominated by Brevoortia tyrannus). However, inter- and intra-specific variation in diet was observed as well. In particular, M. americana consumed fewer engraulids and clupeids, and many more and diverse types of invertebrates, while P. saltatrix consumed more clupeids and less invertebrates. The lack of overlap in diet between the four predators evaluated, and between size groups for each predator, supports previous evidence that these groups feed in trophic guilds defined by species and by size within a species. The highly variable diets for these predators suggest high resolution spatial data are necessary in order to quantify their most important prey and their role in coastal ecosystems.
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Crustacean fisheries often preferentially or exclusively harvest males, resulting in selection that alters sex ratios in fished populations. Sex-biased fisheries may occur when males are larger and fisheries are size-selective, or when regulations limit or prohibit harvest of females to protect sufficient spawning stock to maintain the population. This review explores the evidence for fishery-induced alterations in sex ratios in crustacean fisheries and the resulting effects on reproductive output at the level of the individual and population. Crustacean fisheries exhibit substantial spatial and temporal variation in exploitation, which could lead to hotspots of altered sex ratios. Experimental manipulations simulating the effects of selective harvest indicate that altered sex ratios can lead to sperm limitation and reduction in the reproductive output of individual females. The effects of altered sex ratios on reproduction at the population scale remain poorly understood. Future directions for improving our understanding of the effects of altered sex ratios on reproductive output include focused studies on sperm limitation at high fishery exploitation rates, model simulations of population scale reproductive output that account for individual variation in sperm quantity, and detailed studies of sperm storage and use during fertilization.
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Food webs are a powerful way to represent the diversity, structure, and function of ecological systems. However, the accurate description of food webs requires significant effort in time and resources, limiting their widespread use in ecological studies. Newly published methods allow for the inference of feeding interactions using proxy variables. Here, we compare the accuracy of two recently described methods, as well as describe a composite model of the two, for the inference of feeding interactions using a large, well-described dataset. Both niche and neutral processes are involved in determining whether or not two species will form a feeding link in communities. Three different models for determining niche constraints of feeding interactions are compared, and all three models are extended by incorporating neutral processes, based on relative abundances. The three models compared here infer niche processes through (a) phylogenetic relationships, (b) local species trait distributions (e.g., body size), and (c) a composite of phylogeny and local traits. We show that all three methods perform well at predicting individual species interactions, and that these individual predictions scale up to the network level, resulting in food web structure of inferred networks being similar to their empirical counterparts. Our results indicate that inferring food web structure using phylogenies can be an efficient way of getting summary webs with minimal data, and offers a conservative test of changes in food web structure, particularly when there is low species turnover between sites. Inferences made using traits require more data, but allows for greater understanding of the mechanisms underlying trophic interactions. A composite model of the two methods provides a framework for investigating the importance of how phylogeny, trait distributions, and relative abundances, affect species interactions, and network structure. © 2018 The Authors. Methods in Ecology and Evolution
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The advent of an ecosystem-based approach dramatically expanded the scope of fisheries management, creating a critical need for new kinds of data and quantitative approaches that could be integrated into the management system. Ecosystem models are needed to codify the relationships among drivers, pressures and resulting states, and to quantify the trade-offs between conflicting objectives. Incorporating ecosystem considerations requires moving from the single-species models used in stock assessments, to more complex models that include species interactions, environmental drivers and human consequences. With this increasing model complexity, model fit can improve, but parameter uncertainty increases. At intermediate levels of complexity, there is a ‘sweet spot’ at which the uncertainty in policy indicators is at a minimum. Finding the sweet spot in models requires compromises: for example, to include additional component species, the models of each species have in some cases been simplified from age-structured to logistic or bioenergetic models. In this paper, we illuminate the characteristics, capabilities and short-comings of the various modelling approaches being proposed for ecosystem-based fisheries management. We identify key ecosystem needs in fisheries management and indicate which types of models can meet these needs. Ecosystem models have been playing strategic roles by providing an ecosystem context for single-species management decisions. However, conventional stock assessments are being increasingly challenged by changing natural mortality rates and environmentally driven changes in productivity that are observed in many fish stocks. Thus, there is a need for more tactical ecosystem models that can respond dynamically to changing ecological and environmental conditions.
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Invertebrate catches are increasing globally following the depletion of many finfish stocks, yet stock assessments and management plans for invertebrates are limited, as is an understanding of the ecosystem effects of these fisheries. Using an ecosystem modelling approach, we explored the trade-offs between invertebrate catches and their impacts on the associated ecosystem on the south coast of Wellington, New Zealand. We simulated exploitation of lobster (Jasus edwardsii), abalone (Haliotis australis, H. iris), and sea urchin (Evechinus chloroticus) over a range of depletion levels—from no depletion to local extinction—to estimate changes in target catches and associated effects on other species groups, trophic levels, and benthic and pelagic components. Exploitation of lobster showed the strongest ecosystem effects, followed by abalone and urchin. In all three fisheries, the current exploitation rate exceeds that which produces maximum sustainable yield, with considerable ecosystem effects. Interestingly, a reduced exploitation rate is predicted to increase target catches (and catch-per-unit-effort), thereby strongly reducing ecosystem effects, a win– win situation. Our results suggest that invertebrate exploitation clearly influences ecosystem structure and function, yet the direction and magnitude of responses depend on the target group and exploitation rate. An ecosystem-based fisheries management approach that includes the role of invertebrates would improve the conservation and management of invertebrate resources and marine ecosystems on broader scales.
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The recovery of whale populations from historical depletion may have the potential to noticeably affect Northeast Pacific ecosystems and fisheries. Surplus production models based on whaling catch records were used to reconstruct the historical abundances of five large whale species in the waters surrounding Haida Gwaii, British Columbia. The results suggest that the local abundances of all five species were vastly higher before the onset of modern whaling. A comparison of ecosystem models representing the states of the local marine food web before and after full whale recovery indicates that abundant whales could consume large proportions of the annual production of their principal prey, ranging up to 88% for Pacific herring (Clupea pallasii) and 72% for piscivorous rockfish (Sebastes spp.). Dynamic modelling of the food web effects of whale recovery, including simulations of simultaneous top-down and bottom-up forcing and a Monte Carlo sensitivity analysis, revealed noticeable (∼7–10%) top-down effects on Pacific herring biomass owing to increased predation by humpback and fin whales. However, these effects cannot explain the magnitude of recent declines in local herring biomass. The dynamic modelling results also suggest that top-down effects of whale recovery could result in reduced biomasses of large rockfish as a result of predation by sperm whales, as well as potential cascading effects on many demersal fish groups. These findings have numerous practical implications for ecosystem-based fisheries management and whale conservation strategies in Northeast Pacific waters.
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Invertebrate catches are increasing globally following the depletion of many finfish stocks, yet stock assessments and management plans for invertebrates are limited, as is an understanding of the ecosystem effects of these fisheries. Using an ecosystem modeling approach we explored the trade-offs between invertebrate catches and their impacts on the associated ecosystem on the south coast of Wellington, New Zealand. We simulated exploitation of lobster (Jasus edwardsii), abalone (Haliotis australis, H. iris), and sea urchin (Evechinus chloroticus) over a range of depletion levels -from no depletion to local extinction - to estimate changes in target catches and associated effects on other species groups, trophic levels, and benthic and pelagic components. Exploitation of lobster showed the strongest ecosystem effects, followed by abalone and urchin. In all three fisheries, the current exploitation rate exceeds that which produces maximum sustainable yield, with considerable ecosystem effects. Interestingly, a reduced exploitation rate is predicted to increase target catches (and catch-per-unit-effort), thereby strongly reducing ecosystem effects, a win-win situation. Our results suggest that invertebrate exploitation clearly influences ecosystem structure and function, yet the direction and magnitude of responses depend on the target group and exploitation rate. An ecosystem-based fisheries management approach that includes the role of invertebrates would improve the conservation and management of invertebrate resources and marine ecosystems on broader scales.
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