Allochthonous aquatic subsidies alleviate predation pressure in terrestrial ecosystems

Recalde, Fátima C.; Breviglieri, Crasso Paulo Bosco; Romero, Gustavo Q.

doi:10.1002/ecy.3074

Cited by 16 publications

(16 citation statements)

References 55 publications

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“…In addition, food web stability is highly dependent on the trophic position of the subsidy recipient (Leroux & Loreau, 2008; Polis et al, 1997). Low amounts of inputs tend to support food web stability, whereas large, variable pulses of inputs can have a destabilizing effect through stronger trophic cascades (Huxel & McCann, 1998; Leroux & Loreau, 2008; McCary et al, 2021; Recalde et al, 2020). Understanding the pathways by which subsidies enter food webs and knowing who benefits from them can aid our understanding of individual‐level to community‐level consumer responses.…”

Section: Discussionmentioning

confidence: 99%

“…We tailor this prediction by considering the types of subsidies considered here (i.e., wrack, feces, urine, and food scraps). Stronger upper‐level consumer pathways likely exist in salmon‐subsidized ecosystems (e.g., bears in Helfield & Naiman, 2006) or in ones with emerging aquatic invertebrates (e.g., birds, bats, and spiders in Recalde et al, 2020), where the subsidy is more attractive to upper‐level consumers. Collectively, testing these predictions allowed us to assess how island characteristics can affect both the enrichment of individual components of food webs and the flow of nutrients through island food webs, and, as a result, tie together key theories in island biogeography and food web ecology.…”

Section: Introductionmentioning

confidence: 99%

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Biogeographic features mediate marine subsidies to island food webs

et al. 2022

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Although marine subsidies often enrich terrestrial ecosystems, their influence is known to be context‐dependent. Additionally, the multitrophic impact of marine subsidies has not been traced through food webs across physically diverse islands. Here, we test predictions about how island characteristics can affect marine enrichment of food web constituents and how nutrients flow through island food webs. To evaluate enrichment and trace marine nutrients across food webs, we used stable isotopes of soil, flora, and fauna (n = 4752 samples) collected from 97 islands in British Columbia, Canada. Island area was the strongest predictor of enrichment across taxa; we found that samples were more 15N‐rich on smaller islands. Enrichment declined with distance from shore but less so on small islands, implying a higher per‐unit‐area subsidy effect. These area and distance‐to‐shore effects were taxon‐specific, and nearly twice as strong in basal food web groups. We also found that increases in δ15N correlated with increases in %N in basal trophic groups, as well as in songbirds, implying biologically relevant uptake of a potentially limiting nutrient. Path analysis demonstrated that subsidies in soil flow through plants and detritivores, and into upper‐level consumers. Our results reveal an interplay between island biogeography and marine subsidies in shaping island food webs through bottom‐up processes.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Biogeographic features mediate marine subsidies to island food webs

et al. 2022

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“…Aquatic insects underpin several key functions and services that freshwater ecosystems provide to tropical and subtropical regions. These include detritus processing and biogeochemical cycling, bioturbation, biological control and food sources that fuel and stabilize aquatic and terrestrial food webs [41,42]. Therefore, long-term anthropogenic impact monitoring and mitigation strategies are pivotal in maintaining freshwater ecosystem integrity.…”

Section: Discussionmentioning

confidence: 99%

Pervasive decline of subtropical aquatic insects over 20 years driven by water transparency, non-native fish and stoichiometric imbalance

et al. 2021

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Insect abundance and diversity are declining worldwide. Although recent research found freshwater insect populations to be increasing in some regions, there is a critical lack of data from tropical and subtropical regions. Here, we examine a 20-year monitoring dataset of freshwater insects from a subtropical floodplain comprising a diverse suite of rivers, shallow lakes, channels and backwaters. We found a pervasive decline in abundance of all major insect orders (Odonata, Ephemeroptera, Trichoptera, Megaloptera, Coleoptera, Hemiptera and Diptera) and families, regardless of their functional role or body size. Similarly, Chironomidae species richness decreased over the same time period. The main drivers of this pervasive insect decline were increased concurrent invasions of non-native insectivorous fish, water transparency and changes to water stoichiometry (i.e. N : P ratios) over time. All these drivers represent human impacts caused by reservoir construction. This work sheds light on the importance of long-term studies for a deeper understanding of human-induced impacts on aquatic insects. We highlight that extended anthropogenic impact monitoring and mitigation actions are pivotal in maintaining freshwater ecosystem integrity.

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“…For instance, the loss of a top predator from the terrestrial ecosystem can alter the adjacent aquatic community structure and ecosystem functioning (Breviglieri & Romero, 2017;Romero & Srivastava, 2010). Additionally, changes in aquatic top predators can alter aquatic subsidies to terrestrial organisms (Greig et al, 2012), which could affect terrestrial interactions (Knight et al, 2005;Recalde et al, 2020). Also, despite the well-known effects of predators with different hunting mode on biodiversity and food web structure within ecosystems (Barton & Schmitz, 2009), minimal knowledge is available about how biotic and abiotic changes in an ecosystem (e.g.…”

Section: Introductionmentioning

confidence: 99%

Warming and top predator loss drive direct and indirect effects on multiple trophic groups within and across ecosystems

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et al. 2021

Journal of Animal Ecology

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1. The interspecific interactions within and between adjacent ecosystems strongly depend on the changes in their abiotic and biotic components. However, little is known about how climate change and biodiversity loss in a specific ecosystem can impact the multiple trophic interactions of different biological groups within and across ecosystems.2. We used natural microecosystems (tank-bromeliads) as a model system to investigate the main and interactive effects of aquatic warming and aquatic top predator loss (i.e. trophic downgrading) on trophic relationships in three integrated food web compartments: (a) aquatic micro-organisms, (b) aquatic macroorganisms and (c) terrestrial predators (i.e. via cross-ecosystem effects).3. The aquatic top predator loss substantially impacted the three food web compartments. In the aquatic macrofauna compartment, trophic downgrading increased the filter feeder richness and abundance directly and indirectly via an increase in detritivore richness, likely through a facilitative interaction. For the microbiota compartment, aquatic top predator loss had a negative effect on algae richness, probably via decreasing the input of nutrients from predator biological activities. Furthermore, the more active terrestrial predators responded more to aquatic top predator loss, via an increase in some components of aquatic macrofauna, than more stationary terrestrial predators. The aquatic trophic downgrading indirectly altered the richness and abundance of cursorial terrestrial predators, but these effects had different direction according to the aquatic functional group, filter feeder or other detritivores. The web-building predators were indirectly affected by aquatic trophic downgrading due to increased filter feeder richness. Aquatic warming did not affect the aquatic microor macro-organisms but did positively affect the abundance of web-building terrestrial predators.4. These results allow us to raise a predictive framework of how different anthropogenic changes predicted for the next decades, such as aquatic warming and top predator loss, could differentially affect multiple biological groups through interactions within and across ecosystems.

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Allochthonous aquatic subsidies alleviate predation pressure in terrestrial ecosystems

Cited by 16 publications

References 55 publications

Biogeographic features mediate marine subsidies to island food webs

Biogeographic features mediate marine subsidies to island food webs

Pervasive decline of subtropical aquatic insects over 20 years driven by water transparency, non-native fish and stoichiometric imbalance

Warming and top predator loss drive direct and indirect effects on multiple trophic groups within and across ecosystems

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