Publication Details
Category Text Publication
Reference Category Journals
DOI 10.1111/1365-2656.13627
Document accepted manuscript
Title (Primary) Energy-mediated responses to changing prey size and distribution in marine top predator movements and population dynamics
Author Gallagher, C.A.; Chimienti, M.; Grimm, V.; Nabe-Nielsen, J.
Source Titel Journal of Animal Ecology
Year 2022
Department OESA
Volume 91
Issue 1
Page From 241
Page To 254
Language englisch
Topic T5 Future Landscapes
Supplements Supplement 1
Keywords Agent-based model; climate change effects; energy budgets; harbor porpoise; hidden Markov modelling; marine mammal; physiological ecology; predictive ecology
Abstract
  1. Climate change is modifying the structure of marine ecosystems, including that of fish communities. Alterations in abiotic and biotic conditions can decrease fish size and change community spatial arrangement, ultimately impacting predator species which rely on these communities. To conserve predators and understand drivers of observed changes in their population dynamics, we must advance our understanding of how shifting environmental conditions can impact populations by limiting food available to individuals.
  2. To investigate impacts of changing fish size and spatial aggregation on a top predator population, we applied an existing agent-based model parameterized for harbor porpoises (Phocoena phocoena) which represents animal energetics and movements in high detail. We used this framework to quantify impacts of shifting prey size and spatial aggregation on porpoise movement, space use, energetics, and population dynamics.
  3. Simulated individuals were more likely to switch from area-restricted search to transit behavior with increasing prey size, particularly when starving, due to elevated resource competition. In simulations with highly aggregated prey, higher prey encounter rates counteracted resource competition, resulting in no impacts of prey size on movement behavior.
  4. Reduced energy intake with decreasing prey size and aggregation level caused population decline. A 15% decrease in fish length, for example, resulted in total population collapse. Increasing prey consumption rates by 42.8 ± 4.5% could offset population declines, however this increase was 21.3 ± 12.7% higher than needed to account for changes in total energy availability alone. This suggests that animals in realistic seascapes require additional energy to locate smaller prey which should be considered when assessing impacts of decreased energy availability.
  5. Changes in prey size and aggregation influenced movements and population dynamics of simulated harbor porpoises, revealing that climate-induced changes in prey structure, not only prey abundance, may threaten predator populations. We demonstrate how a population model with realistic animal movements and process-based energetics can be used to investigate population consequences of shifting food availability, such as those mediated by climate change, and provide a mechanistic explanation for how changes in prey structure can impact energetics, behavior, and ultimately viability of predator populations.
Persistent UFZ Identifier https://www.ufz.de/index.php?en=20939&ufzPublicationIdentifier=25323
Gallagher, C.A., Chimienti, M., Grimm, V., Nabe-Nielsen, J. (2022):
Energy-mediated responses to changing prey size and distribution in marine top predator movements and population dynamics
J. Anim. Ecol. 91 (1), 241 - 254 10.1111/1365-2656.13627