Potential role of predators on carbon dynamics of marine ecosystems as assessed by a Bayesian belief network

Spiers, Elisabeth K.A.; Stafford, Richard; Ramírez, Mery; Izurieta, Douglas F. Vera; Cornejo, Mariaherminia; Chavarria, Johnny

doi:10.1016/j.ecoinf.2016.10.003

Cited by 20 publications

(15 citation statements)

References 33 publications

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“…Because pelagic sharks are predominantly top predators, declines in their abundance may entail impacts on marine ecosystems [34,41,61,62,72]. In the northwest Atlantic, Mediterranean and Australia, these sharks play an important role in controlling the abundance and behavior of "mesopredators", such as smaller sharks and rays, which in turn are responsible for the control of prey occupying lower trophic levels within "food webs" [34,61].…”

Section: Introductionmentioning

confidence: 99%

“…In the northwest Atlantic, Mediterranean and Australia, these sharks play an important role in controlling the abundance and behavior of "mesopredators", such as smaller sharks and rays, which in turn are responsible for the control of prey occupying lower trophic levels within "food webs" [34,61]. While the need to reevaluate the effects of predator removal has been recently discussed [40], mainly for particular ecosystems [37,66], there is a consensus that marine predators should be properly managed for the maintenance of demographic persistence, density and risk-driven ecological processes [41,72].…”

Section: Introductionmentioning

confidence: 99%

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Rethinking use and trade of pelagic sharks from Brazil

et al. 2017

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Brazil currently ranks as the 11th producer and 1st importer of shark meat around the world. Data available from the FAO software FishStatJ along with data from regional sources, such as governmental bulletins, scientific papers, gray literature and internet were revisited to identify the main issues surrounding pelagic shark fisheries, trade and consumption in the largest country in South America. Among the main findings, it was noted that Brazil has not properly collected fishery statistics since 2007, that many species of threatened sharks are freely landed and traded even though it is prohibited by local legislation and/or international recommendations (regional fisheries management organizations). The blue shark (Prionace glauca) is the most frequently recorded shark in the official bulletins and is currently a locally targeted species. Additionally, the significant imports of this species from 23 other countries that also provide fins for Asia has drawn attention in recent decades. Regarding consumption, shark is considered to be low-value seafood compared to more common fish, such as groupers and snappers, and most Brazilians actually do not know that they are eating sharks. At present, the proportion of threatened elasmobranchs (in which sharks are included) in Brazil (33%, of 145 species) exceeds the global rate identified for the group (25%), and, until the present moment, no measure related to the management of species has been implemented. As advice, Brazil urgently needs to restructure its fishery information collection systems, management strategies and to tighten sanitary and labeling regulations for the marketing of fish.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rethinking use and trade of pelagic sharks from Brazil

et al. 2017

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“…The removal of so many fish, therefore, must have major ecological implications. Changes in the respiring biomass of the ocean have been predicted to result from removal of fish (Spiers et al, 2016), resulting in more CO 2 production and hence less oceanic capacity for absorbing anthropogenic CO 2 , accelerating both climate change and ocean acidification (Spiers et al, 2016). Such changes are also apparent in other studies; for example, Lynam et al (2017) showed that zooplankton biomass increased as fish stocks decreased across the North Sea, and vice versa as fishing effort changed over time.…”

Section: Sustainability -An Economic and Ecological Concept But Not mentioning

confidence: 88%

“…The lack of a strict dietary need for fish (not to be confused with the need for protein, which may be provided most easily by fish in some communities) is, however, worth bearing in mind. Firstly, the fish we consume is typically of a high trophic level (Yodzis, 2001;Spiers et al, 2016). Largely, eating fish would be the only time a typical human consumes the flesh of a predator.…”

Section: Sustainable Fisheries and Scalementioning

confidence: 99%

Sustainability: A flawed concept for fisheries management?

Stafford

2019

Elementa: Science of the Anthropocene

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The concept of sustainable fishing is well ingrained in marine conservation and marine governance. However, I argue that the concept is deeply flawed; ecologically, socially and economically. Sustainability is strongly related, both historically and currently, to maximum long-term economic exploitation of a system. Counter-intuitively, in fisheries, achieving this economic exploitation often relies on government subsidies. While many fish populations are not sustainably fished biologically, even ‘sustainably harvesting’ fish results in major ecological changes to marine systems. These changes create unknown damage to ecosystem processes, including carbon capture potential of the ocean. The spatial scale of commercial fishing processes can also lead to social and food security issues in local, coastal communities that rely on fish for dietary needs. A radical alternative proposal is provided to the current situation. Ultimately, offshore fishing should be stopped completely and fish catches should rely instead on inshore fisheries. While such an approach may require a change in thinking and human behaviour regarding fish, I demonstrate that there are many benefits of this approach, including ecological, social and to local coastal economies, and few negatives, although management measures and coastal marine protected areas to protect vulnerable species and habitats would still be required. As such, the approach suggested is much more akin to a holistic definition of sustainability or ‘prevention of ecological harm’, rather than the maximum long-term exploitation of an ecosystem which is an underlying assumption of much fisheries and conservation research. While the suggestions in the study would benefit from further ecological, social and economic modelling, any movement towards restricting offshore catches should provide some degree of the benefits detailed.

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“…The observed alterations of the trophic structure, respiration rates and benthic secondary production (indirectly assessed by biomass), in relation to trawling disturbance, is an indication of its negative influence on nutrient and energy fluxes across the food web. As energy transfer in marine systems (across the food web) is predominantly determined by biotic interactions among organisms (e.g., predation, but also competition, facilitation; Strong et al, 2015;Spiers et al, 2016), the capture and conversion of primary production into secondary production by consumers is a key function of the benthos (Strong et al, 2015). Moreover, there is increased evidence that loss of species at higher trophic levels would have more severe effects on the stability of food webs through topdown control, and thus groups such as predators can have a crucial role in carbon and energy cycling (Atwood et al, 2015;Spiers et al, 2016).…”

Section: Diversity and Ecosystem Function Trends Across The Wimmentioning

confidence: 99%

Ecosystem Functioning Under the Influence of Bottom-Trawling Disturbance: An Experimental Approach and Field Observations From a Continental Slope Area in the West Iberian Margin

et al. 2020

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Understanding the effects of bottom-trawling induced changes in benthic community structure, diversity and ecosystem functioning across different benthic-size components is imperative to determine the future sustainability of bottom-trawling fisheries in deepsea regions. In this study, we combined field sampling observations with a pulse-chase experiment on sediments obtained from two stations of interest along the West Iberian Margin (WIM) distinguished by different trawling pressures. We compared these two stations in terms of meio-and macrofauna (infauna) standing stocks, biodiversity and several ecosystem function proxies. These proxies included: (i) 13 C uptake by bacterial communities, (ii) infauna respiration rates, (iii) penetration of 13 C in the sediment, and (iv) sediment pore-water nutrient concentrations. The pulse-chase experimental results were complemented with a larger biological dataset partially compiled from previous studies in the area, to investigate structural and functional diversity ecosystem functioning (respiration) patterns across the WIM. Our observations indicated that different regimes of trawling pressure influenced both macrofaunal respiration rates with disturbed sediments predominantly composed of deposit-/detritus-feeding smallersized macrofauna species. Moreover, sediment biogeochemical functioning (ammonium profiles) and 13 C bacterial uptake showed differences among the two disturbance regimes. On the contrary, the biomass of small-sized biota, including bacteria and meiofauna, did not show marked differences between stations. The general depletion in macrofauna species richness across impacted areas of the study region was also correlated with a reduction in total biomass and respiration, suggesting that the long history of trawling disturbance at the WIM may affect regulatory ecosystem functions. These preliminary findings alert for the impacts of trawling on crucial functions of benthic ecosystems that may be imperceptible to the current tools used in monitoring programs.

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Potential role of predators on carbon dynamics of marine ecosystems as assessed by a Bayesian belief network

Cited by 20 publications

References 33 publications

Rethinking use and trade of pelagic sharks from Brazil

Rethinking use and trade of pelagic sharks from Brazil

Sustainability: A flawed concept for fisheries management?

Ecosystem Functioning Under the Influence of Bottom-Trawling Disturbance: An Experimental Approach and Field Observations From a Continental Slope Area in the West Iberian Margin

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