TY - JOUR A1 - Hixson, Stefanie M. A1 - Sharma, Bhanu A1 - Kainz, Martin J. A1 - Wacker, Alexander A1 - Arts, Michael T. T1 - Production, distribution, and abundance of long-chain omega-3 polyunsaturated fatty acids: a fundamental dichotomy between freshwater and terrestrial ecosystems JF - Environmental reviews = Dossiers environnement N2 - Long-chain polyunsaturated fatty acids (LC-PUFA) are critical for the health of aquatic and terrestrial organisms; therefore, understanding the production, distribution, and abundance of these compounds is imperative. Although the dynamics of LC-PUFA production and distribution in aquatic environments has been well documented, a systematic and comprehensive comparison to LC-PUFA in terrestrial environments has not been rigorously investigated. Here we use a data synthesis approach to compare and contrast fatty acid profiles of 369 aquatic and terrestrial organisms. Habitat and trophic level were interacting factors that determined the proportion of individual omega-3 (n-3) or omega-6 (n-6) PUFA in aquatic and terrestrial organisms. Higher total n-3 content compared with n-6 PUFA and a strong prevalence of the n-3 PUFA eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) characterized aquatic versus terrestrial organisms. Conversely, terrestrial organisms had higher linoleic acid (LNA) and alpha-linolenic acid (ALA) contents than aquatic organisms; however, the ratio of ALA: LNA was higher in aquatic organisms. The EPA + DHA content was higher in aquatic animals than terrestrial organisms, and increased from algae to invertebrates to vertebrates in the aquatic environment. An analysis of covariance (ANCOVA) revealed that fatty acid composition was highly dependent on the interaction between habitat and trophic level. We conclude that freshwater ecosystems provide an essential service through the production of n-3 LC-PUFA that are required to maintain the health of terrestrial organisms including humans. KW - aquatic ecosystems KW - conservation KW - eicosapentaenoic acid KW - docosahexaenoic acid KW - food webs Y1 - 2015 U6 - https://doi.org/10.1139/er-2015-0029 SN - 1208-6053 SN - 1181-8700 VL - 23 IS - 4 SP - 414 EP - 424 PB - NRC Research Press CY - Ottawa ER - TY - JOUR A1 - Wacker, Alexander A1 - Marzetz, Vanessa A1 - Spijkerman, Elly T1 - Interspecific competition in phytoplankton drives the availability of essential mineral and biochemical nutrients JF - Ecology : a publication of the Ecological Society of America N2 - The underlying mechanisms and consequences of competition and diversity are central themes in ecology. A higher diversity of primary producers often results in higher resource use efficiency in aquatic and terrestrial ecosystems. This may result in more food for consumers on one hand, while, on the other hand, it can also result in a decreased food quality for consumers; higher biomass combined with the same availability of the limiting compound directly reduces the dietary proportion of the limiting compound. Here we tested whether and how interspecific competition in phytoplankton communities leads to changes in resource use efficiency and cellular concentrations of nutrients and fatty acids. The measured particulate carbon : phosphorus ratios (C:P) and fatty acid concentrations in the communities were compared to the theoretically expected ratios and concentrations of measurements on simultaneously running monocultures. With interspecific competition, phytoplankton communities had higher concentrations of the monounsaturated fatty acid oleic acid and also much higher concentrations of the ecologically and physiologically relevant long-chain polyunsaturated fatty acid eicosapentaenoic acid than expected concentrations based on monocultures. Such higher availability of essential fatty acids may contribute to the positive relationship between phytoplankton diversity and zooplankton growth, and may compensate limitations by mineral nutrients in higher trophic levels. KW - biodiversity KW - C:P ratio KW - competition KW - eicosapentaenoic acid KW - elemental composition KW - EPA KW - food quality KW - minerals KW - phosphorus KW - polyunsaturated fatty acids KW - PUFA KW - resource use efficiency Y1 - 2015 U6 - https://doi.org/10.1890/14-1915.1 SN - 0012-9658 SN - 1939-9170 VL - 96 IS - 9 SP - 2467 EP - 2477 PB - Wiley CY - Washington ER -