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Abstract Predators mediate the strength of trophic cascades indirectly by decreasing the number of prey consuming a basal resource and by altering prey responses that dictate prey foraging. The strength of these indirect effects further depends on abiotic factors. For example, attributes of the environment, such as turbulent flows in aquatic habitats that disrupt spatial information available from chemical cues, can impose “sensory stresses” that impair the ability of predators or prey to detect each other. The multi-faceted impacts of sensory stress on both the predators and prey create challenges in predicting the overall effect on the trophic cascade. Here, we explore how sensory stress affects the strength of trophic cascades using a tri-trophic dynamical model that incorporates the sensory environment and anti-predatory responses. We explore two crucial parameters that govern outcomes of the model. First, we allow predation rates to either strengthen or weaken depending on whether prey or predators are more sensitive to sensory stress, respectively. Second, we explore scenarios where anti-predatory responses can either drive a strong or weak reduction in prey foraging. We find that sensory stress usually weakens trophic cascades except in scenarios where predators are relatively unaffected by sensory stress and the loss of anti-predatory responses does not affect prey foraging. The model finally suggests that “hydra effects” can manifest, whereby an increase in prey population occurs despite an increase in per capita predation. This last feature emerges due to the interaction between logistic growth of the basal resource and anti-predatory responses reducing the over-consumption of the basal resource.
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Local adaptation in trait-mediated trophic cascades
Predator-induced changes in prey foraging can influence community dynamics by increasing the abundance of basal resources via a trait-mediated trophic cascade. The strength of these cascades may be altered by eco-evolutionary relationships between predators and prey, but the role of basal resources has received limited attention. We hypothesized that trait-mediated trophic cascade strength may be shaped by selection from trophic levels above and below prey. Field and laboratory experiments used snails (Nucella lapillus) from two regions in the Gulf of Maine (GoM) that vary in basal resource availability (e.g. mussels), seawater temperature, and contact history with the invasive green crab,Carcinus maenas. In field and laboratory experiments,Nucellafrom both regions foraged on mussels in the presence or absence of green crab risk cues. In the field,Nucellafrom the northern GoM, where mussels are scarce, were less responsive to risk cues and more responsive to seawater temperature than southernNucella. In the lab, however, northernNucellaforaged and grew more than southern snails in the presence of risk, but foraging and growth were similar in the absence of risk. We suggest that adaptation to basal resource availability may shape geographical variation in the strength of trait-mediated trophic cascades.
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- Award ID(s):
- 2017626
- PAR ID:
- 10525747
- Editor(s):
- Dall, Sasha
- Publisher / Repository:
- The Royal Society
- Date Published:
- Journal Name:
- Proceedings of the Royal Society B: Biological Sciences
- Volume:
- 291
- Issue:
- 2014
- ISSN:
- 0962-8452
- Subject(s) / Keyword(s):
- foraging, plasticity, predation risk, temperature, trait-mediated, trophic level
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1098/rspb.2023.2583
