Are net-spinning caddisflies what they eat? An investigation using controlled diets and fatty acids

Torres-Ruiz, Mónica; Wehr, John D.; Perrone, Alissa A.

doi:10.1899/09-162.1

Cited by 55 publications

(59 citation statements)

References 38 publications

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“…Moreover, seasonal change is unlikely to affect the low‐EPA content of submerged leaves (Torres‐Ruiz and Wehr ). Macroinvertebrate primary consumers in our study streams showed limited ability to synthesize EPA from dietary ALA, suggesting they obtained EPA from food sources that are rich in EPA (Brett and Müller‐Navarra ; Wacker et al ; Torres‐Ruiz et al ). Terrestrial leaves may serve as shelters or play other roles for macroinvertebrates, but offer only weak dietary contributions to macroinvertebrate EPA (Torres‐Ruiz et al ; Lau et al ; Brett et al ).…”

Section: Discussionmentioning

confidence: 87%

“…LC‐PUFA, in particular EPA (20 : 5ω3), docosahexaenoic acid (DHA, 22 : 6ω3), and arachidonic acid (ARA, 20 : 4ω6) are generally essential for invertebrate development, reproduction, and hormone regulation, especially for insect emergence and reproduction (Stanley‐Samuelson ). However, many aquatic animals only have a limited ability to synthesize LC‐PUFA from the shorter chain PUFA alpha‐linolenic acid (ALA, 18 : 3ω3) and linoleic acid (LIN, 18 : 2ω6) (Brett and Müller‐Navarra ; Wacker et al ; Torres‐Ruiz et al ), and they must therefore obtain most of their LC‐PUFA directly from their diet. High LC‐PUFA retention in metazoan consumers means high availability for the next trophic level (Brett and Müller‐Navarra ; Taipale et al ).…”

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confidence: 99%

“…Despite these apparent broad patterns, it is still largely unknown how changes in periphyton FA would consequently affect the FA composition of macroinvertebrates. Although several studies have found that macroinvertebrate FA profiles match their dietary FA (Torres‐Ruiz et al ; Torres‐Ruiz et al ; Guo et al a ), the resolution of periphyton FA on macroinvertebrate FA along spatial and temporal changes of their habitats is poorly understood.…”

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confidence: 99%

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Feeding strategies for the acquisition of high‐quality food sources in stream macroinvertebrates: Collecting, integrating, and mixed feeding

Guo

Bunn

Brett

et al. 2018

Limnology & Oceanography

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Aquatic macroinvertebrates play an important functional role in energy transfer in food webs, linking basal food sources to upper trophic levels that include fish, birds, and humans. However, the trophic coupling of nutritional quality between macroinvertebrates and their food sources is still poorly understood. We conducted a field study in subalpine streams in Austria to investigate how the nutritional quality (measured by long‐chain polyunsaturated fatty acids, LC‐PUFAs) in macroinvertebrates changes relative to their basal food sources. Samples of macroinvertebrates, periphyton, and leaves were collected from 17 streams in July and October 2016 and their fatty acid (FA) composition was analyzed. Periphyton FA varied strongly with time and space, and their trophic effect on macroinvertebrate FA differed among functional feeding groups. The match between periphyton FA and macroinvertebrate FA decreased with increasing trophic levels, but LC‐PUFA content increased with each trophic step from periphyton to grazers and finally predators. Macroinvertebrates fed selectively on, assimilated, and/or actively controlled their LC‐PUFA, especially eicosapentaenoic acid (EPA, 20 : 5ω3) relative to their basal food sources in the face of spatial and temporal changes. Grazer FA profiles reflected periphyton FA with relatively good fidelity, and especially their EPA feeding strategy was primarily linked to periphyton FA variation across seasons. In contrast, shredders appeared to preferentially assimilate more EPA over other FA, which was determined by the availability of high‐quality food over seasons. Predators may more actively control their LC‐PUFA distribution with respect to different quality foods and showed less fidelity to the basal FA profiles in plants and prey. Overall, grazers and shredders showed relatively good fidelity to food FA profiles and performed as both “collectors” and “integrators” for LC‐PUFA requirements across seasons, while predators at higher trophic levels were more “integrators” with added metabolic complexity leading to somewhat more divergent FA profiles. These results are potentially applicable for other aquatic consumers in freshwater and marine ecosystems.

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Section: Discussionmentioning

confidence: 87%

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confidence: 99%

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confidence: 99%

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Feeding strategies for the acquisition of high‐quality food sources in stream macroinvertebrates: Collecting, integrating, and mixed feeding

Guo

Bunn

Brett

et al. 2018

Limnology & Oceanography

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“…The supply of polyunsaturated fatty acids (PUFAs) to aquatic invertebrates is essential and can limit consumer secondary production because PUFAs are metabolically required and cannot be synthesized by the consumer (Muller-Navarra et al, 2000;Arts et al, 2001). A recent study by the authors has shown experimentally that a common stream invertebrate, the caddisfly Hydropsyche sp., must acquire PUFAs from their diet and cannot synthesize many of these essential FAs (Torres-Ruiz et al, 2010). Despite the potential importance of PUFAs for stream consumers and the often-cited significance of leaf litter in the diet of invertebrates in small streams (Vannote et al, 1980), only one study is known that addresses the subject of FA dynamics in leaves during decomposition in streams.…”

Section: Introductionmentioning

confidence: 99%

Changes in the nutritional quality of decaying leaf litter in a stream based on fatty acid content

Torres-Ruiz

Wehr

2010

Hydrobiologia

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We examined the nutritional quality of decaying leaf litter in a third-order forested stream, using measurements of fatty acid (FA) composition over time. We measured changes in concentrations of total, polyunsaturated, microalgal, and microbial marker FAs in mixed-species leaf packs in spring and autumn and effects of including/excluding macroinvertebrates. Initial concentrations of total FAs in litter were significantly less in spring (5.2 mg/g) than in autumn (6.9 mg/g; F = 6.3; P = 0.03), but total FA concentrations in litter placed in the stream declined significantly over 120 days in both spring (62%; F = 10.9; P \ 0.001) and autumn (56%; F = 19.4; P = 0.0001). Quantities of most FAs declined at a greater rate than that of bulk leaf matter. The presence or absence of macroinvertebrates (5 mm vs. 250 lm mesh) had no effect on FA concentration or composition of decomposing litter. Omega-3 polyunsaturated FAs were either nearly absent (20:5x3) or depleted preferentially over other FAs (18:3x3). During decomposition the polyunsaturated FA linoleic acid (18:2x6, common in fungi), declined in concentration more rapidly than other FAs in the spring, but in autumn declined at slower rates, perhaps suggesting greater fungal activity in autumn. Quantities of bacterial (e.g., 16:1x7) and fungal (e.g., 18:1x9) FA markers increased over time in autumn (and 16:1x7 also in spring). Our data provide no evidence for increasing nutritional FA quality of litter during decay and microbial colonization, based on total and polyunsaturated FAs, despite measured increases in bacterial and fungal FA over time. Routine measurements of FA composition of litter could provide insights into the nutrition of allochthonous matter and the importance of fungi and bacteria during decomposition.

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“…Although proportions of Σω3, Σω6, and Σother FA groups did not significantly differ among shredders, collector/gatherers, and predators, their proportions of the five essential FAs did. These differences probably resulted from dissimilar diets among feeding groups, given that FA content and proportions differ among basal resources in streams, and most macroinvertebrates are unlikely, or are at least greatly limited in their ability, to alter their content of these FAs via desaturation and elongation (Guo et al., , ; Torres‐Ruiz et al., , ).…”

Section: Discussionmentioning

confidence: 99%

Urbanisation alters fatty acids in stream food webs

et al. 2019

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Fatty acids are essential to macroinvertebrate growth and reproduction and can indicate food web structure and nutritional quality of basal resources. However, broad‐scale examinations of how catchment land cover and associated stressors affect the proportions of fatty acids (FAs) in stream food webs are few. Here, we: (1) examine relationships among proportions of FAs among benthic periphyton and macroinvertebrate collector/gatherers, shredders, and predators; and (2) test if relationships between periphytic and macroinvertebrate FAs were altered due to the intensity of urban development in catchments. Proportions of the ≥20‐C eicosapentaenoic acid (EPA 20:5ω3), arachidonic acid (ARA 20:4ω6), and docosahexaenoic acid (22:6ω3) indicated collector/gatherers had a diet richer in periphyton than in shredders, which had significantly lower proportions of these FAs. Collector/gatherers were in turn likely to be high‐quality sources of ω3 and ≥ 20‐C FAs for predators, which also had significantly greater EPA and ARA proportions than those in shredders. Linoleic (18:2ω6) and α‐linolenic acid (18:3ω3) comprised the greatest proportions of FAs in shredders, which suggested a diet dominated by leaf litter and associated hyphomycetes. As catchment urbanisation increased, proportions of total ω3 FAs and EPA in periphyton were significantly greater. This pattern also was seen through macroinvertebrate consumers and predators, given that proportions of these FAs in macroinvertebrates also were significantly correlated with factors associated with catchment urbanisation. The significant increase in total ω3 FAs and EPA proportions within shredders indicated that periphyton growth, and their FAs, increased on leaf litter, probably due to greater nutrient concentrations associated with catchment urbanisation. Proportions of total ω6 FAs in biota were not significantly correlated with factors associated with urban development, which could indicate that they were of sufficient abundance for consumers regardless of urban intensity or possible changes in their sources. Our study provides an informative first step that identified notable differences in proportions of FAs among macroinvertebrates in urban streams and an increase in proportions of total ω3 FAs and EPA in periphyton, consumers, and predators as catchment urbanisation increases. Identifying how FA relationships within food webs change in response to catchment alterations and stressors could inform land use and management decisions by linking environmental changes to measures important to ecosystem outcomes.

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Are net-spinning caddisflies what they eat? An investigation using controlled diets and fatty acids

Cited by 55 publications

References 38 publications

Feeding strategies for the acquisition of high‐quality food sources in stream macroinvertebrates: Collecting, integrating, and mixed feeding

Feeding strategies for the acquisition of high‐quality food sources in stream macroinvertebrates: Collecting, integrating, and mixed feeding

Changes in the nutritional quality of decaying leaf litter in a stream based on fatty acid content

Urbanisation alters fatty acids in stream food webs

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