A temporal shift in trophic diversity among a predator assemblage in a warming Arctic

Climate change is leading to northward shifts in species distributions that is altering interspecific interactions at low- and mid-trophic levels. However, little attention has been focused on the effects of redistributions of species on the trophic ecology of a high trophic-level predator assemblage. Here, during a 22-year period (1990–2012) of increasing sea temperature (1.0°C) and decreasing sea ice extent (12%) in Cumberland Sound, Nunavut, Canada, we examined the trophic structure of a near-apex predator assemblage before (1990–2002) and after (2005–2012) an increase in the availability of capelin—generally an indicator species in colder marine environments for a warming climate. Stable isotopes (δ 13 C and δ 15 N) were used in a Bayesian framework to assess shifts in diet, niche size and community-wide metrics for beluga whales ( Delphinapterus leucas ), ringed seals ( Pusa hispida ), Greenland halibut ( Reinhardtius hippoglossoides ) and anadromous Arctic char ( Salvelinus alpinus ). After 2005, consumption of forage fish increased for all predator species, suggesting diet flexibility with changing abiotic and biotic conditions. An associated temporal shift from a trophically diverse to a trophically redundant predator assemblage occurred where predators now play similar trophic roles by consuming prey primarily from the pelagic energy pathway. Overall, these long-term ecological changes signify that trophic shifts of a high trophic-level predator assemblage associated with climate change have occurred in the Arctic food web.

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Temporal shifts in intraguild predation pressure between beluga whales and Greenland halibut in a changing Arctic

Biology Letters ◽

10.1098/rsbl.2017.0433 ◽

2017 ◽

Vol 13 (11) ◽

pp. 20170433 ◽

Cited By ~ 13

Author(s):

David J. Yurkowski ◽

Nigel E. Hussey ◽

Aaron T. Fisk ◽

Kendra L. Imrie ◽

Ross F. Tallman ◽

...

Keyword(s):

Intraguild Predation ◽

Prey Availability ◽

The Arctic ◽

Delphinapterus Leucas ◽

Forage Fish ◽

Greenland Halibut ◽

Predator Species ◽

Beluga Whales ◽

Decadal Scale ◽

Temporal Shifts

Asymmetrical intraguild predation (AIGP), which combines both predation and competition between predator species, is pervasive in nature with relative strengths varying by prey availability. But with species redistributions associated with climate change, the response by endemic predators within an AIGP context to changing biotic–abiotic conditions over time (i.e. seasonal and decadal) has yet to be quantified. Furthermore, little is known on AIGP dynamics in ecosystems undergoing rapid directional change such as the Arctic. Here, we investigate the flexibility of AIGP among two predators in the same trophic guild: beluga ( Delphinapterus leucas ) and Greenland halibut ( Reinhardtius hippoglossoides ), by season and over 30 years in Cumberland Sound—a system where forage fish capelin ( Mallotus villosus ) have recently become more available. Using stable isotopes, we illustrate different predator responses to temporal shifts in forage fish availability. On a seasonal cycle, beluga consumed less Greenland halibut and increased consumption of forage fish during summer, contrasting a constant consumption rate of forage fish by Greenland halibut year-round leading to decreased AIGP pressure between predators. Over a decadal scale (1982–2012), annual consumption of forage fish by beluga increased with a concomitant decline in the consumption of Greenland halibut, thereby indicating decreased AIGP pressure between predators in concordance with increased forage fish availability. The long-term changes of AIGP pressure between endemic predators illustrated here highlights climate-driven environmental alterations to interspecific intraguild interactions in the Arctic.

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Climate change and ocean acidification impacts on lower trophic levels and the export of organic carbon to the deep ocean

Biogeosciences ◽

10.5194/bg-10-5831-2013 ◽

2013 ◽

Vol 10 (9) ◽

pp. 5831-5854 ◽

Cited By ~ 41

Author(s):

A. Yool ◽

E. E. Popova ◽

A. C. Coward ◽

D. Bernie ◽

T. R. Anderson

Keyword(s):

Climate Change ◽

Organic Carbon ◽

Ocean Acidification ◽

21St Century ◽

Trophic Level ◽

Large Scale ◽

World Ocean ◽

Trophic Levels ◽

The Arctic ◽

Marine Biota

Abstract. Most future projections forecast significant and ongoing climate change during the 21st century, but with the severity of impacts dependent on efforts to restrain or reorganise human activity to limit carbon dioxide (CO2) emissions. A major sink for atmospheric CO2, and a key source of biological resources, the World Ocean is widely anticipated to undergo profound physical and – via ocean acidification – chemical changes as direct and indirect results of these emissions. Given strong biophysical coupling, the marine biota is also expected to experience strong changes in response to this anthropogenic forcing. Here we examine the large-scale response of ocean biogeochemistry to climate and acidification impacts during the 21st century for Representative Concentration Pathways (RCPs) 2.6 and 8.5 using an intermediate complexity global ecosystem model, MEDUSA-2.0. The primary impact of future change lies in stratification-led declines in the availability of key nutrients in surface waters, which in turn leads to a global decrease (1990s vs. 2090s) in ocean productivity (−6.3%). This impact has knock-on consequences for the abundance of the low trophic level biogeochemical actors modelled by MEDUSA-2.0 (−5.8%), and these would be expected to similarly impact higher trophic level elements such as fisheries. Related impacts are found in the flux of organic material to seafloor communities (−40.7% at 1000 m), and in the volume of ocean suboxic zones (+12.5%). A sensitivity analysis removing an acidification feedback on calcification finds that change in this process significantly impacts benthic communities, suggesting that a~better understanding of the OA-sensitivity of calcifying organisms, and their role in ballasting sinking organic carbon, may significantly improve forecasting of these ecosystems. For all processes, there is geographical variability in change – for instance, productivity declines −21% in the Atlantic and increases +59% in the Arctic – and changes are much more pronounced under RCP 8.5 than the RCP 2.6 scenario.

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Contrasting changes in space use induced by climate change in two Arctic marine mammal species

Biology Letters ◽

10.1098/rsbl.2018.0834 ◽

2019 ◽

Vol 15 (3) ◽

pp. 20180834 ◽

Cited By ~ 6

Author(s):

Charmain D. Hamilton ◽

Jade Vacquié-Garcia ◽

Kit M. Kovacs ◽

Rolf A. Ims ◽

Jack Kohler ◽

...

Keyword(s):

Climate Change ◽

Marine Mammals ◽

Environmental Changes ◽

Life Cycles ◽

The Arctic ◽

Delphinapterus Leucas ◽

Behavioural Plasticity ◽

Mammal Species ◽

Dietary Specialization ◽

Environmental Pressures

Global warming is inducing major environmental changes in the Arctic. These changes will differentially affect species owing to differences in climate sensitivity and behavioural plasticity. Arctic endemic marine mammals are expected to be impacted significantly by ongoing changes in their key habitats owing to their long life cycles and dependence on ice. Herein, unique biotelemetry datasets for ringed seals (RS; Pusa hispida ) and white whales (WW; Delphinapterus leucas ) from Svalbard, Norway, spanning two decades (1995–2016) are used to investigate how these species have responded to reduced sea-ice cover and increased Atlantic water influxes. Tidal glacier fronts were traditionally important foraging areas for both species. Following a period with dramatic environmental change, RS now spend significantly more time near tidal glaciers, where Arctic prey presumably still concentrate. Conversely, WW spend significantly less time near tidal glacier fronts and display spatial patterns that suggest that they are foraging on Atlantic fishes that are new to the region. Differences in levels of dietary specialization and overall behavioural plasticity are likely reasons for similar environmental pressures affecting these species differently. Climate change adjustments through behavioural plasticity will be vital for species survival in the Arctic, given the rapidity of change and limited dispersal options.

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Drivers of trophic amplification of ocean productivity trends in a changing climate

Biogeosciences ◽

10.5194/bg-11-7125-2014 ◽

2014 ◽

Vol 11 (24) ◽

pp. 7125-7135 ◽

Cited By ~ 53

Author(s):

C. A. Stock ◽

J. P. Dunne ◽

J. G. John

Keyword(s):

Food Web ◽

21St Century ◽

Trophic Level ◽

Net Primary Production ◽

Trophic Levels ◽

The Arctic ◽

Phytoplankton Production ◽

Planktonic Food ◽

Projected Changes ◽

Zooplankton Growth

Abstract. Pronounced projected 21st century trends in regional oceanic net primary production (NPP) raise the prospect of significant redistributions of marine resources. Recent results further suggest that NPP changes may be amplified at higher trophic levels. Here, we elucidate the role of planktonic food web dynamics in driving projected changes in mesozooplankton production (MESOZP) found to be, on average, twice as large as projected changes in NPP by the latter half of the 21st century under a high emissions scenario in the Geophysical Fluid Dynamics Laboratory's ESM2M–COBALT (Carbon, Ocean Biogeochemistry and Lower Trophics) earth system model. Globally, MESOZP was projected to decline by 7.9% but regional MESOZP changes sometimes exceeded 50%. Changes in three planktonic food web properties – zooplankton growth efficiency (ZGE), the trophic level of mesozooplankton (MESOTL), and the fraction of NPP consumed by zooplankton (zooplankton–phytoplankton coupling, ZPC), explain the projected amplification. Zooplankton growth efficiencies (ZGE) changed with NPP, amplifying both NPP increases and decreases. Negative amplification (i.e., exacerbation) of projected subtropical NPP declines via this mechanism was particularly strong since consumers in the subtropics have limited surplus energy above basal metabolic costs. Increased mesozooplankton trophic level (MESOTL) resulted from projected declines in large phytoplankton production. This further amplified negative subtropical NPP declines but was secondary to ZGE and, at higher latitudes, was often offset by increased ZPC. Marked ZPC increases were projected for high-latitude regions experiencing shoaling of deep winter mixing or decreased winter sea ice – both tending to increase winter zooplankton biomass and enhance grazer control of spring blooms. Increased ZPC amplified projected NPP increases in the Arctic and damped projected NPP declines in the northwestern Atlantic and Southern Ocean. Improved understanding of the physical and biological interactions governing ZGE, MESOTL and ZPC is needed to further refine estimates of climate-driven productivity changes across trophic levels.

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Historical changes in mean trophic level of southern Australian fisheries

Marine and Freshwater Research ◽

10.1071/mf13246 ◽

2014 ◽

Vol 65 (10) ◽

pp. 884 ◽

Cited By ~ 5

Author(s):

Heidi K. Alleway ◽

Sean D. Connell ◽

Tim M. Ward ◽

Bronwyn M. Gillanders

Keyword(s):

Trophic Level ◽

Spatial Data ◽

South Australia ◽

Trophic Levels ◽

High Trophic Level ◽

Fishing Pressure ◽

Time Line ◽

The Mean ◽

Mean Trophic Level ◽

Catch Statistics

Decreases in the mean trophic level (MTL) of fishery catches have been used to infer reductions in the abundance of high trophic level species caused by fishing pressure. Previous assessments of southern Australian fisheries have been inconclusive. The objectives of the present study were to provide more accurate estimates of MTL using disaggregated taxonomic and spatial data. We applied the model of MTL to fisheries catch statistics for the state of South Australia from 1951 to 2010 and a novel set of historical market data from 1936 to 1946. Results show that from 1951 to 2010, MTL declined by 0.16 of a trophic level per decade; a rate greater than the global average of 0.10 but equivalent to similar regional investigations in other areas. This change is mainly attributable to large increases in catches of sardine, rather than reductions in the catches of high trophic level species. The pattern is maintained when the historical data is included, providing a time line from 1936 to 2010. Our results show a broadening of the catch of lower trophic levels and suggest care in interpretation of MTL of catches because reductions do not necessarily reflect change in high trophic level species by fishing pressure.

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

10.7287/peerj.preprints.26673 ◽

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.

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Climate change impact on Balearic shearwater through a trophic cascade

Biology Letters ◽

10.1098/rsbl.2011.0225 ◽

2011 ◽

Vol 7 (5) ◽

pp. 702-705 ◽

Cited By ~ 41

Author(s):

C. Luczak ◽

G. Beaugrand ◽

M. Jaffré ◽

S. Lenoir

Keyword(s):

Climate Change ◽

Trophic Cascade ◽

Trophic Levels ◽

Significant Shift ◽

Fish Prey ◽

Sea Temperature ◽

Predator Species ◽

Change Impact ◽

Regional Index

A recent study showed that a critically endangered migratory predator species, the Balearic shearwater Puffinus mauretanicus , rapidly expanded northwards in northeast Atlantic waters after the mid-1990s. As a significant positive correlation was found between the long-term changes in the abundance of this seabird and sea temperature around the British Isles, it was hypothesized that the link between the biogeographic shift and temperature occurred through the food web. Here, we test this conjecture and reveal concomitant changes in a regional index of sea temperature, plankton (total calanoid copepod), fish prey (anchovy and sardine) and the Balearic shearwater for the period 1980–2003. All three trophic levels exhibit a significant shift detected between 1994 and 1996. Our findings therefore support the assertion of both a direct and an indirect effect of climate change on the spatial distribution of post-breeding Balearic shearwater through a trophic cascade.

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

10.7287/peerj.preprints.26673v1 ◽

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

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Trophic ecology of elasmobranchs caught off Gujarat, India, as inferred from stable isotopes

ICES Journal of Marine Science ◽

10.1093/icesjms/fsq170 ◽

2010 ◽

Vol 68 (3) ◽

pp. 547-554 ◽

Cited By ~ 34

Author(s):

Asunción Borrell ◽

Luis Cardona ◽

Ramanathan P. Kumarran ◽

Alejandro Aguilar

Keyword(s):

Stable Isotopes ◽

Isotopic Composition ◽

Trophic Level ◽

Trophic Ecology ◽

Trophic Levels ◽

The Other ◽

Sphyrna Lewini ◽

Rhincodon Typus ◽

Nursery Habitats ◽

Dietary Shifts

Abstract Borrell, A., Cardona, L., Kumarran, R. P., and Aguilar, A. 2011. Trophic ecology of elasmobranchs caught off Gujarat, India, as inferred from stable isotopes. – ICES Journal of Marine Science, 68: . Habitat use and trophic levels were investigated in 13 species of elasmobranch caught off Gujarat, India, through their isotopic composition. Most of the animals were fished commercially and were immature, suggesting that fisheries operate in nursery habitats. All of the sharks analysed except Rhincodon typus had a higher estimated trophic level (>3.8) than rays and guitarfish (<3.8), suggesting a diet of bony fish and cephalopods. The trophic level of Sphyrna lewini and R. typus increased with total length, indicating ontogenetic dietary shifts, but the other species did not follow this trend. According to their δ13C values, R. typus, Mobula diabolus, and, surprisingly, Rhina ancylostoma appeared to be the most pelagic species. In comparison, Stegostoma fasciatum, Pristis pectinata, Rhinobatos granulatus, and Aetomylaeus maculatus appeared to be the most demersal, inshore species, and their δ13C signatures were significantly different from those of the three aforementioned species.

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