Trait-based predation suitability offers insight into effects of changing prey communities

Abstract

Increasing environmental pressures and human impacts are reshaping community structures and species interactions throughout all trophic levels. The morphological and behavioural characteristics of species communities contain key ecological information on why prey species appear attractive to predators but are rarely applied when exploring predator-prey (PP) relationships. Expanding our knowledge on how changing prey communities can alter the food resource suitability (RS) for predators is vital for understanding PP dynamics in changing ecosystems. Detailed predator diet data are commonly restricted to commercially important species and often not available over long temporal scales. To find out whether structural changes of prey communities impact the food RS for predator communities over space and time, we apply a novel framework to describe and interpret changes in predator diet-suitability based on predation-relevant traits of prey. We use information on described feeding links from the literature to compile the prey spectrum for each predator and subsequently translate the prey-species into a prey-trait spectrum. For each predator, we then calculate a frequency-based prey-trait affinity score and relate it to the available food resource pool, the community weighted means of prey traits, resulting in a prey-suitability measure. We aim to reveal whether a described multi-decadal change in the community structure of zoobenthos had an impact on the food suitability for the benthic-feeding fish in a coastal system of the Baltic Sea. We assess the direction of change in resource quality from the perspective of benthic-feeding fish and describe predator-specific responses to examine which species are likely to profit or be disadvantaged by changes in their prey spectrum. Furthermore, we test the relationship between functional diversity of prey communities and food suitability for predators, and whether predation linkage-structures are affected through prey community-changes. Our results show that changes in zoobenthic communities had a positive effect on the food suitability for most benthic-feeding fish, implying more suitable food resources. Species-specific responses of predators suggest varying plasticity to cope with prey assemblages of different trait compositions. Additionally, the functional diversity of zoobenthos had a positive effect on the food suitability for predator fish. The changing trait compositions of prey influenced the PP linkage-structure, indicating varying specialisation of benthic feeding fish towards available food resources. Our findings suggest that changing morphological characteristics of prey can impact food RS features for its predators. This approach enables long-term evaluation of prey quality characteristics where no detailed diet data is available and allows for cross-system comparison as it is not relying on taxonomic identities per se.

Marine epibenthic functional diversity on Flemish Cap (north‐west Atlantic)—Identifying trait responses to the environment and mapping ecosystem functions

“…How much the slow recovery of these benthic communities could impact the fish production and how the lack of recovery of species such as the American plaice could be linked to available benthic food resources remains an open but important question. Trait‐based frameworks could further help to shed light on the effects that changing prey communities may have on the resource quality for their predators (Weigel & Bonsdorff, ). The ‘NAFO Roadmap’ for the development and implementation of an ecosystem approach to fisheries in the NAFO Area (Koen‐Alonso et al, ) has tried to integrate the impacts of fishing activities on benthic communities.…”

“…sources remains an open but important question. Trait-based frameworks could further help to shed light on the effects that changing prey communities may have on the resource quality for their predators (Weigel & Bonsdorff, 2018). The 'NAFO Roadmap' for the development and implementation of an ecosystem approach to fisheries in the NAFO Area (Koen-Alonso et al, 2019) has tried to integrate the impacts of fishing activities on benthic communities.…”

Integrating experimental and distribution data to predict future species patterns

“…One approach towards such methods is, for example, to use functional-traits to explain species responses to their environment 13,29 . Alternatively, our method could also be extended to joint species distribution modeling which would account for interspecific interactions 13,34,80 . Since species response to the environment is typically similar between functionally similar species 13,29 experiments on only a subset of species may inform about the response of functionally similar species as well.…”

A trait‐based framework for understanding predator–prey relationships: Trait matching between a specialist snake and its insect prey

“…Predator–prey relationships traditionally have been interpreted purely based on taxonomy, that is, which species consumes which species. However, the recent surge of interest and advances in trait‐based functional approaches in a variety of fields require a shift of interest to a better understanding of the functional links between predator traits and prey traits (Weigel & Bonsdorff, ). Such trait matching (Brousseau, Gravel, & Handa, ) has at least three benefits.…”

“…A refocusing of interest, however, will need to extend to functional traits beyond body size/mass such as those related to defence against predators (Eitzinger, Rall, Traugott, & Scheu, ). This approach has already been pursued in several empirical studies in aquatic ecosystems (copepods: Kalinoski & DeLong, ; fishes: Sánchez‐Hernández & Cobo, ; fish‐zoobenthos: Worischka, Schmidt, Hellmann, & Winkelmann, ; Weigel & Bonsdorff, ). In terrestrial ecosystems, Brousseau et al () explored trait matching in a feeding experiment with ground beetles and their prey.…”