The trophic importance of epiphytic algae in a freshwater macrophyte system (Potamogeton perfoliatus L.): stable isotope and fatty acid analyses

Jaschinski, Sybill; Brepohl, Daniela C.; Sommer, Ulrich

doi:10.1007/s00027-010-0163-6

Cited by 37 publications

(17 citation statements)

References 53 publications

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“…Marcarelli et al (2011) similarly found that food quality can be more important than quantity of standing crop in driving ecosystem productivity. Second, defended taxa, including both Potamopyrgus and Ostracoda, have been reported to dominate in areas with high macrophyte biomass (Rundle and Ormerod 1991, Humphries et al 1996, Collier et al 1999, Jaschinski et al 2011), which we observed in this study as well.…”

Section: Community Composition and Trophic Interactionssupporting

confidence: 78%

Aquatic macrophytes alter productivity‐richness relationships in eutrophic stream food webs

et al. 2015

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Abstract. Traditional productivity-diversity theory predicts that eutrophication will result in greater species richness due to increased resources at the bottom of the food web. However, few studies on the effects of increasing ecosystem productivity on biological communities have included responses at multiple trophic levels. We hypothesized that the effect of eutrophication on species richness would vary between different trophic levels due to shifts in community composition and trophic interactions. To investigate the mechanisms driving productivity-richness relationships, we constructed food webs for 18 streams across a eutrophication gradient on South Island, New Zealand, and measured productivity, water quality, and habitat characteristics in each stream. A principal components analysis yielded two orthogonal axes of eutrophication: one associated with macrophytes, benthic substrate, and gross primary productivity (GPP) and the other with catchment area, temperature, and algal standing stock (chlorophyll a). Surprisingly, the majority of community response variables, especially defended primary consumer abundance and biomass, were more strongly associated with the macrophyte/habitat axis. The lack of change in abundance and declines in biomass and average mass of predatory invertebrates and fish with increasing eutrophication, despite increases in prey abundance, suggest that energy was not being passed up the food chain to higher trophic levels. The predominance of defended producers (macrophytes) and consumers (snails and microcrustacea) in eutrophic streams likely served as trophic bottlenecks; both are largely inedible by higher trophic levels. Consequently, our results suggest that managers need to focus on preserving food web linkages and energy flow, as well as biodiversity, in eutrophic systems.

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Section: Community Composition and Trophic Interactionssupporting

confidence: 78%

Aquatic macrophytes alter productivity‐richness relationships in eutrophic stream food webs

et al. 2015

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“…Furthermore, indirect facilitation through trophic pathways is also possible. For instance, foundation species may trap or accumulate nutrients, detritus, and other resources (S3 Fig), or mediate a trophic cascade in which predators depend on prey that is non-trophically facilitated by the foundation species [37, 41]. …”

Section: Discussionmentioning

confidence: 99%

Foundation species enhance food web complexity through non-trophic facilitation

et al. 2018

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Food webs are an integral part of every ecosystem on the planet, yet understanding the mechanisms shaping these complex networks remains a major challenge. Recently, several studies suggested that non-trophic species interactions such as habitat modification and mutualisms can be important determinants of food web structure. However, it remains unclear whether these findings generalize across ecosystems, and whether non-trophic interactions affect food webs randomly, or affect specific trophic levels or functional groups. Here, we combine analyses of 58 food webs from seven terrestrial, freshwater and coastal systems to test (1) the general hypothesis that non-trophic facilitation by habitat-forming foundation species enhances food web complexity, and (2) whether these enhancements have either random or targeted effects on particular trophic levels, functional groups, and linkages throughout the food web. Our empirical results demonstrate that foundation species consistently enhance food web complexity in all seven ecosystems. Further analyses reveal that 15 out of 19 food web properties can be well-approximated by assuming that foundation species randomly facilitate species throughout the trophic network. However, basal species are less strongly, and carnivores are more strongly facilitated in foundation species' food webs than predicted based on random facilitation, resulting in a higher mean trophic level and a longer average chain length. Overall, we conclude that foundation species strongly enhance food web complexity through non-trophic facilitation of species across the entire trophic network. We therefore suggest that the structure and stability of food webs often depends critically on non-trophic facilitation by foundation species.

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“…In contrast, herbivorous and omnivorous fish had d 13 C values closest to those of epiphytes and macrophytes. Traditionally, omnivorous fish are considered generalist feeders, although preferring aquatic invertebrates, but may take macrophytes and the associated epiphytes when more nutritious food is scarce (Jaschinski et al, 2011). Piscivorous fish such as topmouth culter and mandarin fish were the top predators in this macrophyte-dominated polyculture system and had the highest d 15 N values.…”

Section: Basal Resources Supporting Consumers: Importance Of Epiphytesmentioning

confidence: 98%

Carbon sources and trophic structure in a macrophyte‐dominated polyculture pond assessed by stable‐isotope analysis

Mao

Zeng

et al. 2016

Freshwater Biology

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Summary Freshwater polyculture systems should efficiently utilise natural food resources and pond habitats with the consequent effects of reducing costs and increasing productivity. However, understanding of the primary carbon sources and food web within polyculture ponds, and especially macrophyte‐dominated ponds, remains limited. Stable‐isotope analysis was used to identify the main carbon sources and describe the trophic patterns of freshwater fauna in a polyculture pond around Lake Gucheng, China. An isotope mixing model (SIAR) was also used to estimate the relative contribution of four basal sources (suspended particulate organic matter [SPOM], sedimentary organic matter [SOM], macrophytes and epiphytes) to invertebrates and different fish trophic groups. Basal resources showed distinct δ13C values, ranging from −24.3 to −20.5‰, which allowed for a powerful discrimination of carbon sources. Consumers were also well separated in δ13C (−24.0 to −20.0‰ for invertebrates and −24.4 to −18.9‰ for fish), suggesting considerable differences in ultimate sources of carbon. Results from the SIAR model indicated that epiphytes were the most important carbon sources for crustaceans, herbivorous fish, omnivorous fish and piscivorous fish, while SPOM made the highest contribution to zooplankton, chironomids, molluscs, annelids, planktivorous fish and benthivorous fish. Mean δ15N values, combined with calculated food source contributions, were used to elucidate the food‐web structure of this polyculture pond, which suggested that carbon fixed by primary producers could be transported up the food chain to piscivorous fish through four main trophic pathways: one based mainly on SPOM, one on both SPOM and SOM, one on SPOM, SOM, macrophytes and epiphytes, and one based on both macrophytes and epiphytes. Our results emphasised the trophic importance of epiphytes on submerged macrophytes, a key component in the polyculture ponds, for the main culture species: Chinese mitten crab (Eriocheir sinensis: Varunidae), freshwater shrimp (Macrobrachium nipponense: Palaemonidae), and high‐value piscivorous fish. This study also revealed the high level of complexity of polyculture pond food webs, and suggests that a diversity of major trophic pathways may be a characteristic of macrophyte‐dominated aquatic ecosystems.

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The trophic importance of epiphytic algae in a freshwater macrophyte system (Potamogeton perfoliatus L.): stable isotope and fatty acid analyses

Cited by 37 publications

References 53 publications

Aquatic macrophytes alter productivity‐richness relationships in eutrophic stream food webs

Aquatic macrophytes alter productivity‐richness relationships in eutrophic stream food webs

Foundation species enhance food web complexity through non-trophic facilitation

Carbon sources and trophic structure in a macrophyte‐dominated polyculture pond assessed by stable‐isotope analysis

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