Cross-ecosystem fluxes: Export of polyunsaturated fatty acids from aquatic to terrestrial ecosystems via emerging insects

Martin‐Creuzburg, Dominik; Kowarik, Carmen; Straile, Dietmar

doi:10.1016/j.scitotenv.2016.10.156

Cited by 86 publications

(94 citation statements)

References 65 publications

(25 reference statements)

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“…However, because individual predatory Perlidae stoneflies are relatively large, the total amount of DHA in a Perlidae stonefly may still be profitable for in‐stream or riparian predators from a foraging efficiency perspective. In general, our findings for DHA are also consistent with previous findings in other predatory emergent insects, such as dragonflies (Popova et al, ) and phantom midges ( Chaoborus flavicans ; Martin‐Creuzburg, Kowarik, & Straile, ).…”

Section: Discussionsupporting

confidence: 92%

Aquatic and terrestrial resources are not nutritionally reciprocal for consumers

et al. 2019

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Aquatic and terrestrial ecosystems are connected through reciprocal fluxes of energy and nutrients that can subsidize consumers. Past research on reciprocal aquatic–terrestrial subsidies to consumers has generally focused on subsidy quantity while ignoring major differences in the nutritional composition of aquatic and terrestrial resources. Because aquatic resources contain substantially more highly unsaturated omega‐3 fatty acids (HUFAs) than terrestrial resources, aquatic subsidies may play a unique role by supplying these critical compounds to both aquatic and terrestrial consumers. Here, we first characterized nutritional quality in terms of HUFA content in aquatic and terrestrial insect prey. We then used bulk stable isotope analyses to estimate subsidy use by stream and riparian consumers coupled with compound‐specific stable isotope analyses, which allowed us to document consumer HUFA sources. Finally, in order to understand the nutritional importance of aquatic‐derived HUFAs for riparian consumers, we conducted manipulative diet experiments on Eastern Phoebe (Sayornis phoebe) chicks in the laboratory. Aquatic insects were significantly enriched in HUFAs, mainly in terms of eicosapentaenoic acid (EPA), compared with terrestrial insects. Stream fishes relied mainly upon aquatic resources, while insectivorous birds varied in their use of aquatic subsidies across sites. However, like stream fishes, Eastern Phoebe chicks received HUFAs from aquatic insects, even when they were heavily reliant upon terrestrial insects for their overall diet. In the laboratory, dietary HUFAs, such as those supplied by aquatic insects, increased the growth rate and condition of Eastern Phoebe chicks. This study demonstrates that aquatic and terrestrial subsidies are not nutritionally reciprocal from the perspective of consumers because aquatic resources are the main source of critical fatty acids for both stream and riparian consumers. It also confirms previous findings on the nutritional importance of HUFAs for riparian birds, demonstrating that an insectivorous riparian lifestyle influences avian nutritional needs. Finally, our findings raise the possibility that birds and other riparian insectivores may experience nutritional mismatches with terrestrial prey if they do not have access to high‐quality aquatic subsidies as a consequence of aquatic habitat degradation or shifts in consumer and resource phenology. A free Plain Language Summary can be found within the Supporting Information of this article.

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Section: Discussionsupporting

confidence: 92%

Aquatic and terrestrial resources are not nutritionally reciprocal for consumers

et al. 2019

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“…However, primary consumers in both systems were found to have very similar body N:P ratios, suggesting that N may be available in excess for aquatic consumers, leading to elevated N:P excretion/egestion ratios (Elser et al, ). Higher nutrient or fatty acid availability in the donor ecosystem also may increase the nutrient or fatty acid content in the body tissues of animal consumers in that ecosystem, with subsequent effects on the quality of their excretion/egestion and carcasses (Heintz et al, ; Small & Pringle, ; Twining et al, ; Martin‐Creuzburg, Kowarik & Straile, ). Animals' diet in the donor ecosystem also may interact with animals' body stoichiometry, as an animal with a low body N:P ratio feeding on a diet with a high N:P ratio will have to consume more food to obtain sufficient P, thus excreting a larger amount of N (Vanni, ).…”

Section: Donor Ecosystem Characteristicsmentioning

confidence: 99%

“…Provision of complementary resources may be more likely when the donor and recipient ecosystems differ substantially from one another. For example, because aquatic and terrestrial systems often differ in stoichiometry and limiting resources, inputs that move from an aquatic ecosystem into a terrestrial ecosystem, or vice versa , may be more likely to provide different resources than those already available in the recipient ecosystem (Elser et al, ; Nowlin, Vanni & Yang, ; Sitters et al, ; Twining et al, ; Martin‐Creuzburg et al, ).…”

Section: Recipient Ecosystem – Physical/chemical Characteristicsmentioning

confidence: 99%

Context dependency of animal resource subsidies

2018

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The transport of resource subsidies by animals has been documented across a range of species and ecosystems. Although many of these studies have shown that animal resource subsidies can have significant effects on nutrient cycling, ecosystem productivity, and food‐web structure, there is a great deal of variability in the occurrence and strength of these effects. Here we propose a conceptual framework for understanding the context dependency of animal resource subsidies, and for developing and testing predictions about the effects of animal subsidies over space and time. We propose a general framework, in which abiotic characteristics and animal vector characteristics from the donor ecosystem interact to determine the quantity, quality, timing, and duration (QQTD) of an animal input. The animal input is translated through the lens of recipient ecosystem characteristics, which include both abiotic and consumer characteristics, to yield the QQTD of the subsidy. The translated subsidy influences recipient ecosystem dynamics through effects on both trophic structure and ecosystem function, which may both influence the recipient ecosystem's response to further inputs and feed back to influence the donor ecosystem. We present a review of research on animal resource subsidies across ecosystem boundaries, placed within the context of this framework, and we discuss how the QQTD of resource subsidies can influence trophic structure and ecosystem function in recipient ecosystems. We explore the importance of understanding context dependency of animal resource subsidies in increasingly altered ecosystems, in which the characteristics of both animal vectors and donor and recipient ecosystems may be changing rapidly. Finally, we make recommendations for future research on animal resource subsidies, and resource subsidies in general, that will increase our understanding and predictive capacity about their ecosystem effects.

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“…Total export of EPA+DHA from the aquatic ecosystem by amphibians in our study was greater than values reported for three anurans emerging from a Russian lake (1.47 mg/m 2 ; Yermokhin et al., ). Amphibians exported LC‐PUFAs to the terrestrial ecosystem at levels comparable to aquatic insect emergence in several systems (Borisova et al., ; Gladyshev, Kharitonov, et al., ; Gladyshev, Sushchik, Yurchenko, et al., ), but the amount of EPA, DHA, and ARA exported from aquatic systems may be driven by the community composition of emerging taxa, and hydroperiod (Martin‐Creuzburg, Kowarik, & Straile, ; Moyo et al., ; Sushchik et al., , ). The importance of emerging aquatic insects for riparian predators has been well documented (as reviewed by Baxter et al., ; Richardson, Zhang, & Marczak, ).…”

Section: Discussionmentioning

confidence: 99%

Subsidies of long‐chain polyunsaturated fatty acids from aquatic to terrestrial environments via amphibian emergence

Fritz

Whiles

Trushenski³

2019

Freshwater Biology

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Resource subsidies across aquatic‐terrestrial boundaries can alter predator distribution and biomass and elicit trophic cascades. Most studies have focused on the size of cross‐boundary fluxes, but the impact of a subsidy is also mediated by quality and relative abundance of similar resources in the recipient habitat. Long‐chain polyunsaturated fatty acids (LC‐PUFAs) are necessary for proper physiological function, are unevenly distributed across the landscape, and animals differ greatly in their ability to synthesize them from biochemical precursors, which creates the potential for limitation and increases their possible importance as a subsidy. We examined whole‐body LC‐PUFA content and export in eight species of emerging amphibian metamorphs across eight temporary ponds in a wetland complex. We found that whole‐body content and export of LC‐PUFAs varied across species, but were generally within the ranges of other amphibian studies and several freshwater fish and aquatic insects. Anurans exported higher amounts of LC‐PUFAs than salamanders, largely due to the higher emergence biomass of anurans. As such, the export of LC‐PUFAs closely mirrored the biomass export for each species. Larger ponds exported higher amounts of eicosapentaenoic acid and docosahexaenoic acid, but some smaller ponds exported more per unit wetted area, indicating the potential importance of small ponds at a landscape scale. Given their vital physiological roles, the uneven distribution of aquatic‐origin LC‐PUFAs could have far reaching effects on terrestrial predators.

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Cross-ecosystem fluxes: Export of polyunsaturated fatty acids from aquatic to terrestrial ecosystems via emerging insects

Cited by 86 publications

References 65 publications

Aquatic and terrestrial resources are not nutritionally reciprocal for consumers

Aquatic and terrestrial resources are not nutritionally reciprocal for consumers

Context dependency of animal resource subsidies

Subsidies of long‐chain polyunsaturated fatty acids from aquatic to terrestrial environments via amphibian emergence

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