Temporal shifts in intraspecific and interspecific diet variation among 3 stream predators

Falke, Landon P.; Henderson, Jeremy S.; Novák, Márk; Preston, Daniel L.

doi:10.1086/707599

Cited by 14 publications

(17 citation statements)

References 99 publications

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“…Empirical studies have confirmed that seasonality is a major source of trophic niche variation (e.g. Falke et al, 2020;Varpe & Fiksen, 2010;Shutt et al, 2020) that has implications for individual fitness (Durant et al, 2005;Hipfner, 2008) and affects the demography of populations (Miller-Rushing et al, 2010). In response to low resource availability, trophic niche expansion is predicted by the Optimal Foraging Theory (OFT; see Perry & Pianka 1997).…”

Section: -Introductionmentioning

confidence: 99%

DNA metabarcoding reveals adaptive seasonal variation of individual trophic traits in a critically endangered fish

Villsen

Corse

Meglécz

et al. 2021

Preprint

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Dietary studies are critical for understanding foraging strategies and have important applications in conservation and habitat management. We applied a robust metabarcoding protocol to characterize the diet of the critically endangered freshwater fish Zingel asper and conducted modelling and simulation analyses to characterize and identify some of the drivers of individual trophic trait variation in this species. We found that intra-specific competition and ontogeny had minor effects on the trophic niche of Z. asper. Instead, our results suggest that the majority of trophic niche variation was driven by seasonal variation in ecological opportunity (in our case, the seasonal variation in the availability of preferred prey types). Overall, our results are in line with the optimal foraging theory and suggest that Z. asper is specialized on a few ephemeropteran prey species (Baetis fuscatus and Ecdyonurus) but adapts its foraging by becoming more opportunistic as its favoured prey seasonally decline. Despite the now widespread usage of metabarcoding, very few studies have attempted to study inter- and intra-populational individual trophic traits variation with metabarcoding data. This study illustrates how metabarcoding data obtained from feces can be combined with modelling and simulation approaches to test hypotheses in the conventional analytic framework of trophic analysis.

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Section: -Introductionmentioning

confidence: 99%

DNA metabarcoding reveals adaptive seasonal variation of individual trophic traits in a critically endangered fish

Villsen

Corse

Meglécz

et al. 2021

Preprint

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“…In general, differential space use with snail size might be related to physical stress (e.g., high turbulence in swift flows)(Holomuzki & Biggs, 2007) and/or predator avoidance (Turner et al., 2000; Turner & Montgomery, 2003). In our study system, shallow, rocky habitat might provide refuge for smaller Juga that are most vulnerable to predation from crayfish, Pacific giant salamanders, and sculpin, of which the larger individuals tend to occupy deeper pools more often (Falke et al., 2020; Preston et al., 2018, 2021; Segui, 2019). Predation risk could therefore explain why we observed lower densities of snails in deeper habitats, but larger individual snails, which are less susceptible to predation (Preston et al., 2018; Segui, 2019).…”

Section: Discussionmentioning

confidence: 97%

Freshwater disease hotspots: Drivers of fine‐scale spatial heterogeneity in trematode parasitism in streams

Falke

Preston

2021

Freshwater Biology

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1. Populations of stream organisms often show large heterogeneity in space, which can substantially influence community dynamics and ecosystem functioning.However, few studies have examined spatial heterogeneity of parasites in lotic ecosystems, especially at fine spatial scales (e.g., within stream reaches).2. We quantified parasite infections in 3,255 host snails (Juga plicifera) at 1-m intervals along three second-order stream reaches to examine relationships between trematode parasite infections, fine-scale heterogeneity in host characteristics (density and size), and the stream environment (depth, allochthonous materials, flow velocity, and substrate rugosity). We then conducted a field experiment to specifically test the effect of resource heterogeneity in the form of leaf litter on trematode densities (i.e., infected snails per unit area), which represents a

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“…By sampling predator stomach contents for Juga snails, we were able to test the prediction that predation rates on snails by aquatic predators are relatively low (Hawkins & Furnish, 1987; Warren et al., 1964). Of the free‐living aquatic consumers sampled, only Pacific giant salamanders consumed a significant quantity of snails (see also Esselstyn & Wildman, 1997; Falke et al., 2020). The large size and robust shells of Juga snails prevent their widespread consumption relative to other macroinvertebrate prey.…”

Section: Discussionmentioning

confidence: 99%

“…We estimated the biomass flux from Juga snails into Pacific giant salamanders, cutthroat trout and reticulate sculpin using diet data that was collected in summer (June/July), fall (September) and spring (April; see Falke et al., 2020; Preston et al., 2019). Stream predators were collected during electroshocking, as described above.…”

Section: Methodsmentioning

confidence: 99%

Trematode parasites exceed aquatic insect biomass in Oregon stream food webs

Preston

Layden

Segui

et al. 2021

Journal of Animal Ecology

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Although parasites are increasingly recognized for their ecosystem roles, it is often assumed that free‐living organisms dominate animal biomass in most ecosystems and therefore provide the primary pathways for energy transfer. To examine the contributions of parasites to ecosystem energetics in freshwater streams, we quantified the standing biomass of trematodes and free‐living organisms at nine sites in three streams in western Oregon, USA. We then compared the rates of biomass flow from snails Juga plicifera into trematode parasites relative to aquatic vertebrate predators (sculpin, cutthroat trout and Pacific giant salamanders). The trematode parasite community had the fifth highest dry biomass density among stream organisms (0.40 g/m2) and exceeded the combined biomass of aquatic insects. Only host snails (3.88 g/m2), sculpin (1.11 g/m2), trout (0.73 g/m2) and crayfish (0.43 g/m2) had a greater biomass. The parasite ‘extended phenotype’, consisting of trematode plus castrated host biomass, exceeded the individual biomass of every taxonomic group other than snails. The substantial parasite biomass stemmed from the high snail density and infection prevalence, and the large proportional mass of infected hosts that consisted of trematode tissue (M = 31% per snail). Estimates of yearly biomass transfer from snails into trematodes were slightly higher than the combined estimate of snail biomass transfer into the three vertebrate predators. Pacific giant salamanders accounted for 90% of the snail biomass consumed by predators. These results demonstrate that trematode parasites play underappreciated roles in the ecosystem energetics of some freshwater streams.

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Temporal shifts in intraspecific and interspecific diet variation among 3 stream predators

Cited by 14 publications

References 99 publications

DNA metabarcoding reveals adaptive seasonal variation of individual trophic traits in a critically endangered fish

DNA metabarcoding reveals adaptive seasonal variation of individual trophic traits in a critically endangered fish

Freshwater disease hotspots: Drivers of fine‐scale spatial heterogeneity in trematode parasitism in streams

Trematode parasites exceed aquatic insect biomass in Oregon stream food webs

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