Variation in the diet of beluga whales in response to changes in prey availability: insights on changes in the Beaufort Sea ecosystem

The eastern Beaufort Sea (EBS) beluga whale Delphinapterus leucas population has experienced a 20 yr decline in inferred growth rates of individuals, which is hypothesized to have resulted from changes in prey availability. We used fatty acid signatures and stable isotope ratios to reconstruct the proportional contributions of 14 prey species to the diets of 178 beluga whales from 2011 to 2014. Prey estimates using quantitative fatty acid signature analysis suggest that EBS beluga whales primarily consume Arctic cod Boreogadus saida, a species highly sensitive to climate change. Prey estimates varied with year and sex and size class of the whales, with large males consuming the highest proportions of Arctic cod, and females consuming the highest proportions of capelin Mallotus villosus. Estimated proportional contributions of Arctic cod to beluga diet decreased from 2011 to 2014, coinciding with an increase in capelin. Belugas consumed the highest proportions of capelin and the lowest proportions of cod in 2014, the same year in which body condition indices were lowest in the whales. We hypothesize that changing conditions in the Beaufort Sea ecosystem may result in a decreased consumption of Arctic cod by belugas and increased consumption of capelin, which may result in a decline in condition. This may predominately affect females and juveniles since they consume the highest proportions of capelin; however, long-term monitoring is needed for confirmation. Understanding inter-annual variation in prey, and the longer-term nutritional implications of shifting from an Arctic cod- to a capelin-dominated diet should be a priority for monitoring EBS predators.

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Review of Estimating Trophic Relationships by Quantitative Fatty Acid Signature Analysis

Journal of Marine Science and Engineering ◽

10.3390/jmse8121030 ◽

2020 ◽

Vol 8 (12) ◽

pp. 1030

Author(s):

Junbo Zhang ◽

Chonglan Ren ◽

Hu Zhang ◽

Fang Yin ◽

Shuo Zhang ◽

...

Keyword(s):

Fatty Acid ◽

First Generation ◽

Trophic Relationships ◽

Research Progress ◽

Signature Analysis ◽

Fatty Acid Signature ◽

Predator Prey ◽

Quantitative Ecology ◽

Improper Use

The dynamic predator–prey relations in the food web are vital for understanding the function and structure of ecosystems. Dietary estimation is a research hotspot of quantitative ecology, providing key insights into predator–prey relationships. One of the most promising approaches is quantitative fatty acid signature analysis (QFASA), which is the first generation of statistical tools to estimate the quantitative trophic predator–prey relationships by comparing the fatty acid (FA) signatures among predators and their prey. QFASA has been continuously widely applied, refined and extended since its introduction. This article reviewed the research progress of QFASA from development and application. QFASA reflects the long-term diet of predator, and provides the quantitative dietary composition of predator, but it is sensitive to the metabolism of predator. The calibration coefficients (CCs) and the FA subset are two crucial parameters to explain the metabolism of predators, but the incorrect construction or improper use of CCs and the FA subset may cause bias in dietary estimation. Further study and refinement of the QFASA approach is needed to identify recommendations for which CCs and subsets of FA work best for different taxa and systems.

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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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Lipid dynamics and trophic patterns in Pleuragramma antarctica life stages

Antarctic Science ◽

10.1017/s0954102015000036 ◽

2015 ◽

Vol 27 (5) ◽

pp. 429-438 ◽

Cited By ~ 7

Author(s):

Carolina Giraldo ◽

Patrick Mayzaud ◽

Eric Tavernier ◽

Marc Boutoute ◽

Florian Penot ◽

...

Keyword(s):

Fatty Acid ◽

Prey Availability ◽

Ontogenetic Changes ◽

Fatty Acid Signature ◽

Lipid Dynamics ◽

Sampling Locations ◽

Key Species ◽

Vertical Segregation ◽

A Minor ◽

Minor Extent

AbstractThe aim of this study was to clarify the trophic patterns of the key species Pleuragramma antarctica in the Dumont d’Urville Sea, through its development and possible changes according to sampling locations. Variability in diet composition of larvae, juvenile and adult P. antarctica was analysed using fatty acid markers. Analysis of lipid class in P. antarctica reflected lipid accumulation with increasing size at all sampling stations. The fatty acid composition of triacylglycerol highlighted ontogenetic changes in the diet. Phytoplankton markers, such as C16PUFA:C16 and EPA:DHA ratios >1, and carnivorous markers in larvae suggested an omnivorous diet. Comparison between the fatty acid signature of P. antarctica older stages (juveniles and adults) and zooplankton species using OPLS-discriminant analysis indicated that juveniles fed mainly on euphausiid larvae and to a minor extent on copepods, and confirmed that non-herbivorous copepods were the main prey for adults. Our results suggest that different feeding patterns and a generalist strategy in P. antarctica with juveniles feeding on bigger prey than adults, probably as a result of prey availability according to their vertical segregation pattern.

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Anthropogenic Scarring in Long-term Photo-identification Records of Cook Inlet Beluga Whales, Delphinapterus leucas

Marine Fisheries Review ◽

10.7755/mfr.82.3-4.3 ◽

2021 ◽

pp. 20-40

Author(s):

Tamara L. McGuire ◽

Amber D. Stephens ◽

John R. McClung ◽

Christopher Garner ◽

Kathleen A. Burek-Huntington ◽

...

Keyword(s):

Delphinapterus Leucas ◽

Cook Inlet ◽

Beluga Whales ◽

Photo Identification

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Microplastics in beluga whales (Delphinapterus leucas) from the Eastern Beaufort Sea

Marine Pollution Bulletin ◽

10.1016/j.marpolbul.2019.110723 ◽

2020 ◽

Vol 150 ◽

pp. 110723 ◽

Cited By ~ 10

Author(s):

R.C. Moore ◽

L. Loseto ◽

M. Noel ◽

A. Etemadifar ◽

J.D. Brewster ◽

...

Keyword(s):

Beaufort Sea ◽

Delphinapterus Leucas ◽

Beluga Whales

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Legacy contaminants in the Eastern Beaufort Sea beluga whales (Delphinapterus leucas): Are temporal trends reflecting regulations?

Arctic Science ◽

10.1139/as-2017-0049 ◽

2018 ◽

Cited By ~ 3

Author(s):

Marie Nöel ◽

Lisa L. Loseto ◽

Gary Stern

Keyword(s):

Temporal Trends ◽

Beaufort Sea ◽

Delphinapterus Leucas ◽

Beluga Whales

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Predation of archival tagged Dolly Varden, Salvelinus malma, reveals predator avoidance behaviour and tracks feeding events by presumed beluga whale, Delphinapterus leucas, in the Beaufort Sea

Animal Biotelemetry ◽

10.1186/s40317-021-00271-x ◽

2021 ◽

Vol 9 (1) ◽

Author(s):

Colin P. Gallagher ◽

Luke Storrie ◽

Michael B. Courtney ◽

Kimberly L. Howland ◽

Ellen V. Lea ◽

...

Keyword(s):

Predator Avoidance ◽

Beaufort Sea ◽

Avoidance Behaviour ◽

Delphinapterus Leucas ◽

Feeding Frequency ◽

Dolly Varden ◽

Salvelinus Malma ◽

Beluga Whales ◽

Predation Event ◽

Stomach Temperature

Abstract Background We report compelling evidence suggesting a predation event of a pop-up satellite archival tagged anadromous Dolly Varden (Salvelinus malma) by a marine mammal during summer in the Beaufort Sea based on abrupt changes in temperature and vertical movements. This observation provides insight on predator avoidance behaviour by Dolly Varden and the predator’s feeding frequency while the tag was ingested. Based on published distribution and ecology information, we presumed the predator was a beluga whale (Delphinapterus leucas). Supplemental satellite telemetry data from previously tagged Dolly Varden and beluga whales were used to determine the extent of spatial and vertical overlap between species in the area where predation occurred. Results Prior to the predation event, depths and temperatures occupied by the tagged Dolly Varden averaged 1.1 m and 3.1 °C, respectively. On July 7, 2020, depths remained shallow apart from a sudden dive to 12.5 m (16:45 UTC) followed by a precipitous increase in temperature from 4.4 to 27.1 °C (16:52 UTC) suggesting predation by an endotherm. Subsequent readings indicated the endotherm had a resting stomach temperature of 36.1 °C. Including the predation event, eight separate feeding events were inferred during the 20-h period the tag was ingested (before presumed regurgitation) based on subsequent declines in stomach temperatures (mean decline to 31.1 °C) that took an average of 24.1 min to return to resting temperature. The predator occupied mainly shallow depths (mean = 2.3 m), overlapping with tagged belugas that spent 76.9% of their time occupying waters ≤ 2.5 m when frequenting the area occupied by tagged Dolly Varden in the Canadian Beaufort Sea in July. Back-calculation based on tag drift and mean displacement by tagged belugas indicated the predation likely occurred west of the Mackenzie Delta. Conclusion Our findings provide new information on both anti-predator behaviour by, and marine predators of, Dolly Varden in the Beaufort Sea. We provide the first estimate of feeding frequency and stomach temperature recovery in a presumed wild beluga, and evidence for shallow foraging behaviour by belugas. Elucidating the likely predator and exploring the extent of overlap between Dolly Varden and beluga whales contributes towards knowledge on the trophic interactions in the Beaufort Sea.

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