Elevated light and nutrients alter the nutritional quality of stream periphyton

Cashman, Matthew J.; Wehr, John D.; Truhn, Kam

doi:10.1111/fwb.12142

Cited by 59 publications

(56 citation statements)

References 54 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…These findings might be related to physiological responses of periphyton to differences in nutrient concentrations. Some studies have reported that added nutrients lead to an increase in the proportions of ALA in periphyton (Cashman, Wehr, & Truhn, 2013;Guo et al, 2016;Hill et al, 2011), but unfortunately we did not analyse periphyton fatty acids in this study. In phytoplankton, low nutrient concentrations lead to the production of PUFA-poor triacylglycerols, whereas high nutrient concentrations lead to an increase of PUFA-rich galactolipids in the algae (Guschina & Harwood, 2009).…”

Section: Discussionmentioning

confidence: 91%

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

et al. 2019

View full text Add to dashboard Cite

1. Aquatic and terrestrial ecosystems differ fundamentally in the abundance of longchained polyunsaturated fatty acids (PUFAs), such as eicosapentaenoic acid (EPA; 20:5n-3), which are produced by aquatic algae, but only in low quantities by terrestrial plants. Aquatic insects, such as Chironomidae (non-biting midges) feed on algae during their larval stage, making them rich in EPA and therefore high-quality prey for insectivores after emergence. However, the magnitude of EPA subsidies from aquatic insects may be different among water bodies in response to abiotic (e.g. nutrient load) as well as biotic factors (e.g. food web structure).2. To test the predation effects of crucian carp (Carassius carassius), nutrient concentrations, and Chironomidae community composition on the fatty acid export from aquatic ecosystems, we conducted a 25-day experiment across 20 1,500-L mesocosms covering a total phosphorus (TP) gradient of 20-1,000 µg/L.3. Twice a week, we collected adult emerging Chironomidae and found differences in fatty acid composition in the two most abundant chironomid species emerging from the mesocosms. Two PUFAs, α-linolenic acid and EPA, contributed to most of the variation in Chironomidae fatty acid content across the nutrient gradient.Whereas the proportions of α-linolenic acid were positively correlated to the mesocosm TP concentration, we found a negative correlation for the proportions of Chironomidae EPA and mesocosm TP concentration. However, despite lower biomass-specific EPA content at higher TP, higher biomass of emerging Chironomidae at intermediate TP concentrations resulted in higher total export of PUFAs from water to land. 4. Predation pressure from carp decreased the biomass of emerging Chironomidae on average 8-fold. Chironomidae biomass showed a hump-shaped relationship along the TP-gradient and was strongly influenced by periphyton biomass. 5. Export rates of EPA and fatty acids in general responded in a quadratic manner along the nutrient gradient, reaching a maximum value at a TP of 400 µg/L and decreasing thereafter.

show abstract

Section: Discussionmentioning

confidence: 91%

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

et al. 2019

View full text Add to dashboard Cite

show abstract

“…The LC‐PUFA content of periphyton is sensitive to seasonal and spatial variation in stream environmental conditions (Hill et al ; Cashman et al ; Guo et al ). For example, the extent of FA unsaturation in algae can vary with temperature.…”

mentioning

confidence: 99%

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

View full text Add to dashboard Cite

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.

show abstract

“…Although not correlated with nutrients in our study, increases in proportions of Σω3 FAs and EPA in periphyton could have been associated with increased nutrients in more urban catchments, given their well‐documented mechanistic links to increased FA production (Dalu, Galloway, Richoux, & Froneman, ; Guo et al., ; Whorley & Wehr, ), although high levels of nutrients also can lead to reduced proportions of ≥20‐C FAs in algae (Cashman et al., ). Within agricultural systems, biofilms contained greater concentrations of important FA compounds as nutrient availability increased, despite exhibiting decreased taxonomic diversity and more eutrophic indicative taxa (Whorley & Wehr, , ).…”

Section: Discussionmentioning

confidence: 55%

“…The strong correlations of Σω3 FAs and EPA proportions with chloride concentrations could indicate nutrient effects as well, because chloride is a conservative tracer of water delivered to streams from sources affected by human activities, and is less affected than nutrients by biological uptake and transformation. Canopy cover by riparian trees, which was qualitatively abundant at most sites, may have further promoted higher proportions of periphyton EPA and ω3 FAs by reducing oxidative damage to their carbon double bonds and by reducing the amount of surplus carbon stored as saturated, monounsaturated, and shorter 18‐C FAs under high light conditions (Cashman et al., ; Hill et al., ; Twining et al., ).…”

Section: Discussionmentioning

confidence: 99%

Urbanisation alters fatty acids in stream food webs

et al. 2019

Self Cite

View full text Add to dashboard Cite

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.

show abstract

Elevated light and nutrients alter the nutritional quality of stream periphyton

Cited by 59 publications

References 54 publications

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

The emergence of fatty acids—Aquatic insects as vectors along a productivity gradient

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

Urbanisation alters fatty acids in stream food webs

Contact Info

Product

Resources

About