Export of dietary lipids via emergent insects from eutrophic fishponds

Type Article
Date 2023
Language English
Author(s) Fehlinger Lena1, 2, Mathieu-Resuge MargauxORCID1, Pilecky Matthias1, 2, Parmar Tarn Preet3, Twining Cornelia W.4, Martin-Creuzburg Dominik5, Kainz Martin J.ORCID1, 2
Affiliation(s) 1 : WasserCluster Lunz - Biologische Station GmbH; Inter-university Center for Aquatic Ecosystem Research, Dr. Carl Kupelwieser Promenade 5, 3293, Lunz am See, Austria
2 : University for Continuing Education Krems, Dr.-Karl-Dorrek-Straße 30, 3500, Krems, Austria
3 : Department of Biology, Limnological Institute, University of Konstanz, Mainaustraße 252, 78464, Konstanz, Germany
4 : Department of Fish Ecology and Evolution, EAWAG: Swiss Federal Institute of Aquatic Sciences and Technology, Seestrasse 79, 6047, Kastanienbaum, Switzerland
5 : Department of Aquatic Ecology, Research Station Bad Saarow, BTU Cottbus-Senftenberg, Seestraße 45, 15526, Bad Saarow, Germany
Source Hydrobiologia (0018-8158) (Springer Science and Business Media LLC), 2023 , Vol. 850 , P. 3241-3256
DOI 10.1007/s10750-022-05040-2
Keyword(s) Dietary energy, Eutrophic, Fishpond, Aquatic insects, Emergence, Ecosystem services

Fishponds, despite being globally abundant, have mainly been considered as food production sites and have received little scientific attention in terms of their ecological contributions to the surrounding terrestrial environment. Emergent insects from fishponds may be important contributors of lipids and essential fatty acids to terrestrial ecosystems. In this field study, we investigated nine eutrophic fishponds in Austria from June to September 2020 to examine how Chlorophyll-a concentrations affect the biomass of emergent insect taxa (i.e., quantity of dietary subsidies; n = 108) and their total lipid and long-chain polyunsaturated fatty acid content (LC-PUFA, i.e., quality of dietary subsidies; n = 94). Chironomidae and Chaoboridae were the most abundant emergent insect taxa, followed by Trichoptera, Ephemeroptera, and Odonata. A total of 1068 kg of emergent insect dry mass were exported from these ponds (65.3 hectares). Chironomidae alone exported 103 kg of total lipids and 9.4 kg of omega-3 PUFA. Increasing Chl-a concentrations were associated with decreasing biomass export and a decrease in total lipid and LC-PUFA export via emergent Chironomidae. The PUFA composition of emergent insect taxa differed significantly from dietary algae, suggesting selective PUFA retention by insects. The export of insect biomass from these eutrophic carp ponds was higher than that previously reported from oligotrophic lakes. However, lower biomass and diversity are exported from the fishponds compared to managed ponds. Nonetheless, our data suggest that fishponds provide crucial ecosystem services to terrestrial consumers by contributing essential dietary nutrients to consumer diets via emergent insects.

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