scholarly journals Bottom–Up Impacts of Forecasted Climate Change on the Eastern Bering Sea Food Web

2021 ◽  
Vol 8 ◽  
Author(s):  
George A. Whitehouse ◽  
Kerim Y. Aydin ◽  
Anne B. Hollowed ◽  
Kirstin K. Holsman ◽  
Wei Cheng ◽  
...  
Keyword(s):  
Climate Change ◽  
Food Web ◽  
Fisheries Management ◽  
Bering Sea ◽  
Status Quo ◽  
Ecosystem Dynamics ◽  
Trophic Levels ◽  
Emission Scenarios ◽  
Bottom Up ◽  
Eastern Bering Sea

Recent observations of record low winter sea-ice coverage and warming water temperatures in the eastern Bering Sea have signaled the potential impacts of climate change on this ecosystem, which have implications for commercial fisheries production. We investigate the impacts of forecasted climate change on the eastern Bering Sea food web through the end of the century under medium- and high-emissions climate scenarios in combination with a selection of fisheries management strategies by conducting simulations using a dynamic food web model. The outputs from three global earth system models run under two greenhouse gas emission scenarios were dynamically downscaled using a regional ocean and biogeochemical model to project ecosystem dynamics at the base of the food web. Four fishing scenarios were explored: status quo, no fishing, and two scenarios that alternatively assume increased fishing emphasis on either gadids or flatfishes. Annual fishery quotas were dynamically simulated by combining harvest control rules based on model-simulated stock biomass, while incorporating social and economic tradeoffs induced by the Bering Sea’s combined groundfish harvest cap. There was little predicted difference between the status quo and no fishing scenario for most managed groundfish species biomasses at the end of the century, regardless of emission scenario. Under the status quo fishing scenario, biomass projections for most species and functional groups across trophic levels showed a slow but steady decline toward the end of the century, and most groups were near or below recent historical (1991–2017) biomass levels by 2080. The bottom–up effects of declines in biomass at lower trophic levels as forecasted by the climate-enhanced lower trophic level modeling, drove the biomass trends at higher trophic levels. By 2080, the biomass projections for species and trophic guilds showed very little difference between emission scenarios. Our method for climate-enhanced food web projections can support fisheries managers by informing strategic guidance on the long-term impacts of ecosystem productivity shifts driven by climate change on commercial species and the food web, and how those impacts may interact with different fisheries management scenarios.

scholarly journals Evaluating management strategies for eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment

2011 ◽  
Vol 68 (6) ◽  
pp. 1297-1304 ◽  
Author(s):  
James N. Ianelli ◽  
Anne B. Hollowed ◽  
Alan C. Haynie ◽  
Franz J. Mueter ◽  
Nicholas A. Bond
Keyword(s):  
Climate Change ◽  
Bering Sea ◽  
Management Strategies ◽  
Walleye Pollock ◽  
Status Quo ◽  
Theragra Chalcogramma ◽  
Recruitment Pattern ◽  
Control Rules ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma

Abstract Ianelli, J. N., Hollowed, A. B., Haynie, A. C., Mueter, F. J., and Bond, N. A. 2011. Evaluating management strategies for eastern Bering Sea walleye pollock (Theragra chalcogramma) in a changing environment. – ICES Journal of Marine Science, 68: 1297–1304. The impacts of climate change on fish and fisheries is expected to increase the demand for more accurate stock projections and harvest strategies that are robust to shifting production regimes. To address these concerns, we evaluate the performance of fishery management control rules for eastern Bering Sea walleye pollock stock under climate change. We compared the status quo policy with six alternative management strategies under two types of recruitment pattern simulations: one that follows temperature-induced trends and the other that follows a stationary recruitment pattern similar to historical observations. A subset of 82 Intergovernmental Panel on Climate Change climate models provided temperature inputs from which an additional 100 stochastic simulated recruitments were generated to obtain the same overall recruitment variability as observed for the stationary recruitment simulations. Results indicate that status quo management with static reference points and current ecosystem considerations will result in much lower average catches and an increased likelihood of fishery closures, should reduced recruitment because of warming conditions hold. Alternative reference point calculations and control rules have similar performance under stationary recruitment relative to status quo, but may offer significant gains under the changing environmental conditions.

scholarly journals Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes

2013 ◽  
Vol 71 (2) ◽  
pp. 406-416 ◽  
Author(s):  
T. O. M. Reilly ◽  
H. M. Fraser ◽  
R. J. Fryer ◽  
J. Clarke ◽  
S. P. R. Greenstreet
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Trophic Levels ◽  
Top Down ◽  
Bottom Up ◽  
Control Processes ◽  
Top Predators ◽  
Environmental Status ◽  
Fish Predators ◽  
Firth Of Forth

Abstract Reilly, T. O. M., Fraser, H. M., Fryer, R. J., Clarke, J., and Greenstreet, S. P. R. 2014. Interpreting variation in fish-based food web indicators: the importance of “bottom-up limitation” and “top-down control” processes. – ICES Journal of Marine Science, 71: 406–416. Proposed indicators for the Marine Strategy Framework Directive (MSFD) food webs Descriptor focus on structural elements of food webs, and in particular on the abundance and productivity of top predators. However, the inferences that can be drawn from such indicators depend on whether or not the predators are “bottom-up limited” by the availability of their prey. Many seabird populations appear to be “bottom-up limited” so that variation in their reproductive success and/or abundance reflects changes in lower trophic levels. Here we find that gadoid fish predators off the Firth of Forth, southeast Scotland, do not appear to be “bottom-up limited” by the biomass of their main prey, 0-group sandeels; gadoid biomass and feeding performance was independent of sandeel biomass. Variability in food web indicators based on these gadoid predators seems to impart little insight into underlying processes occurring at lower trophic levels in the local food web. The implications of this in terms of how the currently proposed MSFD food web indicators should be used and interpreted are considered, and the ramifications in terms of setting targets representing good environmental status for both fish and seabird communities are discussed.

Primacy of bottom-up effects on a butterflyfish assemblage

2016 ◽  
Vol 67 (8) ◽  
pp. 1175 ◽  
Author(s):  
Susannah M. Leahy ◽  
Garry R. Russ ◽  
Rene A. Abesamis
Keyword(s):  
Climate Change ◽  
Water Quality ◽  
Coral Reefs ◽  
Fisheries Management ◽  
Negative Association ◽  
Feeding Guilds ◽  
Top Down ◽  
Management Tools ◽  
Bottom Up ◽  
Anthropogenic Stressors

The question of whether biological systems are maintained by top-down versus bottom-up drivers is a recurring one in ecology. It is a particularly important question to address in the management of coral reefs, which are at risk from a variety of anthropogenic stressors. Here, we explicitly test whether the abundance of different feeding guilds of coral-associated Chaetodon butterflyfishes are controlled by top-down or bottom-up drivers, and we assess the relative influence of all statistically significant drivers. We find that the abundance and species richness of Chaetodon butterflyfishes are predominately determined by bottom-up drivers. The abundance of corallivores is primarily driven by availability of branching and tabular live corals, whereas the abundance of generalists is most strongly influenced by a negative association with macroalgal cover. We also find evidence of weak top-down control on the abundance of corallivorous butterflyfish by gape-limited mesopredators, but no such effects on generalist butterflyfish. Our findings indicate that conservation of coral reefs for Chaetodon butterflyfishes must include management at a larger spatial scale in order to reduce the effect of coral reef stressors such as declining water quality and climate change, but should also include implementation of fisheries management tools in order to increase local herbivory.

scholarly journals Food web structure of the epibenthic community at the sea ice edge in Baffin Bay, Canada

2018 ◽  
Author(s):  
Gustavo Yunda-Guarin ◽  
Philippe Archambault ◽  
Guillaume Massé ◽  
Christian Nozais
Keyword(s):  
Climate Change ◽  
Sea Ice ◽  
Food Web ◽  
Trophic Levels ◽  
The Arctic ◽  
Feeding Guilds ◽  
Food Web Structure ◽  
Baffin Bay ◽  
Ice Edge ◽  
Sea Ice Edge

In polar areas, the pelagic-benthic coupling plays a fundamental role in ensuring organic matter flow across depths and trophic levels. Climate change impacts the Arctic’s physical environment and ecosystem functioning, affecting the sequestration of carbon, the structure and efficiency of the benthic food web and its resilience.In the Arctic Ocean, highest atmospheric warming tendencies (by ~0.5°C) occur in the east of Baffin Bay making this area an ideal site to study the effects of climate change on benthic communities. We sampled epibenthic organisms at 13 stations bordering the sea ice between June and July 2016. The epibenthic taxonomic composition was identified and grouped by feeding guilds. Isotopic signatures (δ13C - δ15N), trophic levels and trophic separation and redundancy were measured and quantified at each station. In the light of the results obtained, the stability of the benthic community in the Baffin Bay at the sea ice edge is discussed.

scholarly journals Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change

2011 ◽  
Vol 68 (6) ◽  
pp. 1284-1296 ◽  
Author(s):  
Franz J. Mueter ◽  
Nicholas A. Bond ◽  
James N. Ianelli ◽  
Anne B. Hollowed
Keyword(s):  
Climate Change ◽  
Bering Sea ◽  
Late Summer ◽  
Walleye Pollock ◽  
Future Climate ◽  
Future Climate Change ◽  
Theragra Chalcogramma ◽  
Climate Projections ◽  
Eastern Bering Sea ◽  
Walleye Pollock Theragra Chalcogramma

Abstract Mueter, F. J., Bond, N. A., Ianelli, J. N., and Hollowed, A. B. 2011. Expected declines in recruitment of walleye pollock (Theragra chalcogramma) in the eastern Bering Sea under future climate change. – ICES Journal of Marine Science, 68: 1284–1296. A statistical model is developed to link recruitment of eastern Bering Sea walleye pollock (Theragra chalcogramma) to variability in late summer sea surface temperatures and to the biomass of major predators. The model is based on recent advances in the understanding of pollock recruitment, which suggest that warm spring conditions enhance the survival of early larvae, but high temperatures in late summer and autumn are associated with poor feeding conditions for young-of-year pollock and reduced recruitment in the following year. A statistical downscaling approach is used to generate an ensemble of late summer temperature forecasts through 2050, based on a range of IPCC climate projections. These forecasts are used to simulate future recruitment within an age-structured stock projection model that accounts for density-dependent effects (stock–recruitment relationship), the estimated effects of temperature and predation, and associated uncertainties. On average, recruitment in 2040–2050 should expectedly decline by 32–58% relative to a random recruitment scenario, depending on assumptions about the temperature relationship, the magnitude of density-dependence, and future changes in predator biomass. The approach illustrated here can be used to evaluate the performance of different management strategies and provide long-term strategic advice to managers confronted with a rapidly changing climate.

scholarly journals Food-web dynamics under climate change

2017 ◽  
Vol 284 (1867) ◽  
pp. 20171772 ◽  
Author(s):  
Lai Zhang ◽  
Daisuke Takahashi ◽  
Martin Hartvig ◽  
Ken H. Andersen
Keyword(s):  
Climate Change ◽  
Food Web ◽  
Ecosystem Function ◽  
Trophic Levels ◽  
Physiological Effects ◽  
Ecological Communities ◽  
Temperature Changes ◽  
Thermal Niche ◽  
The Impact ◽  
Food Web Model

Climate change affects ecological communities through its impact on the physiological performance of individuals. However, the population dynamic of species well inside their thermal niche is also determined by competitors, prey and predators, in addition to being influenced by temperature changes. We use a trait-based food-web model to examine how the interplay between the direct physiological effects from temperature and the indirect effects due to changing interactions between populations shapes the ecological consequences of climate change for populations and for entire communities. Our simulations illustrate how isolated communities deteriorate as populations go extinct when the environment moves outside the species' thermal niches. High-trophic-level species are most vulnerable, while the ecosystem function of lower trophic levels is less impacted. Open communities can compensate for the loss of ecosystem function by invasions of new species. Individual populations show complex responses largely uncorrelated with the direct impact of temperature change on physiology. Such complex responses are particularly evident during extinction and invasion events of other species, where climatically well-adapted species may be brought to extinction by the changed food-web topology. Our results highlight that the impact of climate change on specific populations is largely unpredictable, and apparently well-adapted species may be severely impacted.

scholarly journals Fisheries management for regime-based ecosystems: a management strategy evaluation for the snow crab fishery in the eastern Bering Sea

2012 ◽  
Vol 70 (5) ◽  
pp. 955-967 ◽  
Author(s):  
Cody S. Szuwalski ◽  
André E. Punt
Keyword(s):  
Fisheries Management ◽  
Bering Sea ◽  
Management Strategy ◽  
Management Strategies ◽  
Regime Shifts ◽  
Snow Crab ◽  
Management Strategy Evaluation ◽  
Eastern Bering Sea ◽  
Strategy Evaluation ◽  
Spawning Biomass

Abstract Szuwalski, C., and Punt A. E. 2013. Fisheries management for regime-based ecosystems: a management strategy evaluation for the snow crab fishery in the eastern Bering Sea. – ICES Journal of Marine Science, 70: 955–967. Regime shifts are a prominent feature of the physical environment of some ecosystems and have the potential to influence stock productivity. However, few management strategies or harvest control rules (HCRs) consider the possibility of changes in stock productivity. A management strategy evaluation is conducted for the snow crab (Chionoecetes opilio) fishery in the eastern Bering Sea, an ecosystem influenced by regime shifts. Operating models that project recruitment as a single average (i.e. the current basis for management advice), regime-based with no relationship between recruitment and spawning biomass, and regime-based with control of recruitment oscillating between environmental conditions and spawning biomass are considered. An HCR that accounts for shifts in recruitment regime is compared with the status quo HCR for each operating model. The regime-based HCR increases yield and decreases variability in yield at the cost of a higher probability of overfishing in regime-based systems. However, the regime-based HCR slightly decreases yield (no change in variability) and increases the probability of overfishing in non-regime-based systems. Identifying changes in productivity that are definitely driven by environmental regime rather than fishing pressure is the largest difficulty in implementing these rules.

scholarly journals Spatio-temporal distribution of euphausiids: an important component to understanding ecosystem processes in the Gulf of Alaska and eastern Bering Sea

2016 ◽  
Vol 73 (8) ◽  
pp. 2020-2036 ◽  
Author(s):  
Kirsten A. Simonsen ◽  
Patrick H. Ressler ◽  
Christopher N. Rooper ◽  
Stephani G. Zador
Keyword(s):  
Primary Production ◽  
Bering Sea ◽  
Gulf Of Alaska ◽  
Additive Models ◽  
Trophic Levels ◽  
Production Model ◽  
Trawl Survey ◽  
Large Spatial Scale ◽  
Eastern Bering Sea ◽  
Abundance And Distribution

Abstract Euphausiids (principally Thysanoessa spp.) are found in high abundance in both the eastern Bering Sea (EBS) and the Gulf of Alaska (GOA). They are an important part of these cold-water coastal and pelagic ecosystems as a key prey item for many species, including marine mammals, seabirds, and fish, forming an ecological link between primary production and higher trophic levels. Acoustic-trawl (AT) survey methods provide a means of monitoring euphausiid abundance and distribution over a large spatial scale. Four years of AT and bottom-trawl survey data (2003, 2005, 2011, and 2013) were available from consistently sampled areas around Kodiak Island, including Shelikof Strait, Barnabas Trough, and Chiniak Trough. We identified euphausiid backscatter using relative frequency response and targeted trawling, and created an annual index of abundance for euphausiids. This index has broad application, including use in the stock assessments for GOA walleye pollock (Gadus chalcogrammus) and other species, as an ecosystem indicator, and to inform ecological research. We then used generalized additive models (GAMs) to examine the relationship between relative euphausiid abundance and potential predictors, including pollock abundance, temperature, bottom depth, and primary production. Model results were compared with an updated GAM of euphausiid abundance from the EBS to determine if the factors driving abundance and distribution were consistent between both systems. Temperature was not a strong predictor of euphausiid abundance in the GOA as in the EBS; warmer temperatures and lack of seasonal ice cover in the GOA may be a key difference between these ecosystems. Pollock abundance was significant in both the GOA and the EBS models, but was not a strongly negative predictor of euphausiid abundance in either system, a result not consistent with top-down control of euphausiid abundance.

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