Fluxes of Biomass and Essential Polyunsaturated Fatty Acids from Water to Land via Chironomid Emergence from a Mountain Lake

The taxonomic composition, seasonal dynamics, and emergence intensity of chironomid adults (the Chironomidae family) merging from Oiskoe mountain oligotrophic lake (Western Sayan, Southern Siberia) have been established. The value of the annual emergence of chironomid adults averages 0.42 g wet weight m−2 in the lake area and approaches the value of potential emergence, which is calculated based on the estimate of zoobenthos secondary production. For the first time the fatty-acid composition and contents of essential omega-3 polyunsaturated fatty acids (PUFAs) are compared between the larvae and adult stages of chironomids. The PUFA content per wet weight unit in adults is more than 7 times higher than that in larvae. The PUFA flux per lake area unit resulting from the chironomid emergence amounted to 1.752 mg m−2 y−1, which is over 10 times lower than the global estimate for the emergence of amphibiotic insects. Calculations show that the PUFA flux brought with the chironomid emergence per land unit of the studied mountain territory is very low when compared to that for other landscapes, with the exception of the shoreline part of the territory with a width of 15 m, in which the PUFA flux is comparable to that in productive landscapes

Stable isotope fractionation of fatty acids of Daphnia fed laboratory cultures of microalgae

We tested a comparatively new method of tracing of natural food webs, compound-specific isotope analysis (CSIA) of fatty acids (FA), using laboratory culture of Daphnia galeata fed Chlorella vulgaris and Cryptomonas sp. In general, Daphnia had significantly lighter carbon stable isotope composition of most fatty acids, including essential, than those of their food, microalgae. Thus, our results did not support the pivotal premise of the FA-CSIA application for food web analysis, i.e., transmitting the isotope ‘signal’ of essential FAs to consumers from their food without any modification. Moreover, the values of isotope fractionation of particular FAs in the consumer relative to its food were not constant, but varied from 1.35‰ to 7.04‰. The different isotope fractionation (depletion) values of diverse FAs in consumer were probably caused by different processes of their synthesis, catabolism and assimilation. More work is evidently to be done for correct interpretation of results of FA-CSIA during field studies for tracing of natural food webs

Essential PUFA in Physiology and Metabolism of Fish and Human: Functions, Needs, Sources

The long chain polyunsaturated fatty acids (PUFAs) of the omega-3 family (ω3 or n-3), namely eicosapentaenoic acid (EPA, 20:5n-3) and docosahexaenoic acid (DHA, 22:6n-3), are recognized as molecules of high physiological values for animals of different taxonomic groups, including humans. N-3 PUFAs provide the normal functioning of the cardiovascular and nervous systems, immunity and metabolism in general, and their use is preventive. The medicinal properties of these PUFAs are ambiguous and are being actively discussed in the literature. The main source of EPA and DHA for human is fish. The content of n-3 PUFAs in fish depends on a number of factors and, as a result, varies widely. The needs of the different fish species in the PUFAs are not the same. Some species efficiently synthesize EPA and DHA from their precursors, while others obtain these FAs only with food. Moreover, n-3 PUFAs play important roles in the metabolism of all fishes. The catch of wild fish has reached its limit, but it does not satisfy the needs of mankind in n-3 PUFAs. To reduce the deficiency of EPA + DHA in human nutrition, there are several ways: aquaculture, biotechnology of microorganisms (single cell oils) and genetic engineering

Stable isotope fractionation of fatty acids of Daphnia fed laboratory cultures of microalgae

We tested a comparatively new method of tracing of natural food webs, compound-specific isotope analysis (CSIA) of fatty acids (FA), using laboratory culture of Daphnia galeata fed Chlorella vulgaris and Cryptomonas sp. In general, Daphnia had significantly lighter carbon stable isotope composition of most fatty acids, including essential, than those of their food, microalgae. Thus, our results did not support the pivotal premise of the FA-CSIA application for food web analysis, i.e., transmitting the isotope ‘signal’ of essential FAs to consumers from their food without any modification. Moreover, the values of isotope fractionation of particular FAs in the consumer relative to its food were not constant, but varied from 1.35‰ to 7.04‰. The different isotope fractionation (depletion) values of diverse FAs in consumer were probably caused by different processes of their synthesis, catabolism and assimilation. More work is evidently to be done for correct interpretation of results of FA-CSIA during field studies for tracing of natural food webs

Fluxes of Biomass and Essential Polyunsaturated Fatty Acids from Water to Land via Chironomid Emergence from a Mountain Lake

The taxonomic composition, seasonal dynamics, and emergence intensity of chironomid adults (the Chironomidae family) merging from Oiskoe mountain oligotrophic lake (Western Sayan, Southern Siberia) have been established. The value of the annual emergence of chironomid adults averages 0.42 g wet weight m−2 in the lake area and approaches the value of potential emergence, which is calculated based on the estimate of zoobenthos secondary production. For the first time the fatty-acid composition and contents of essential omega-3 polyunsaturated fatty acids (PUFAs) are compared between the larvae and adult stages of chironomids. The PUFA content per wet weight unit in adults is more than 7 times higher than that in larvae. The PUFA flux per lake area unit resulting from the chironomid emergence amounted to 1.752 mg m−2 y−1, which is over 10 times lower than the global estimate for the emergence of amphibiotic insects. Calculations show that the PUFA flux brought with the chironomid emergence per land unit of the studied mountain territory is very low when compared to that for other landscapes, with the exception of the shoreline part of the territory with a width of 15 m, in which the PUFA flux is comparable to that in productive landscapes

Export of aquatic productivity, including highly unsaturated fatty acids, to terrestrial ecosystems via Odonata

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Based on 31-year field study of the abundance and biomass of 18 species of odonates in the Barabinsk Forest– Steppe(Western Siberia, Russia),we quantified the contribution of odonates to the export of aquatic productivity to surrounding terrestrial landscape. Emergence varied from 0.8 to 4.9 g of wet biomass per m2 of land area per year. Average export of organic carbon was estimated to be 0.30 g·m−2·year−1, which is comparable with the average production of herbivorous terrestrial insects in temperate grasslands. Moreover, in contrast to terrestrial insects, emerging odonates contained high quantities of highly unsaturated fatty acids (HUFA), namely eicosapentaenoic acid (20:5n-3, EPA), and docosahexaenoic acid (22:6n-3, DHA), which are known to be essential for many terrestrial animals, especially for birds. The export of EPA+DHA by odonates was found to be 1.92– 11.76 mg·m−2·year−1, which is equal to an average general estimation of the export of HUFA by emerging aquatic insects. Therefore, odonates appeared to be a quantitatively and qualitatively important conduit of aquatic productivity to forest-steppe ecosystem

Export of aquatic productivity, including highly unsaturated fatty acids, to terrestrial ecosystems via Odonata

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.Based on 31-year field study of the abundance and biomass of 18 species of odonates in the Barabinsk Forest– Steppe(Western Siberia, Russia),we quantified the contribution of odonates to the export of aquatic productivity to surrounding terrestrial landscape. Emergence varied from 0.8 to 4.9 g of wet biomass per m2 of land area per year. Average export of organic carbon was estimated to be 0.30 g·m−2·year−1, which is comparable with the average production of herbivorous terrestrial insects in temperate grasslands. Moreover, in contrast to terrestrial insects, emerging odonates contained high quantities of highly unsaturated fatty acids (HUFA), namely eicosapentaenoic acid (20:5n-3, EPA), and docosahexaenoic acid (22:6n-3, DHA), which are known to be essential for many terrestrial animals, especially for birds. The export of EPA+DHA by odonates was found to be 1.92– 11.76 mg·m−2·year−1, which is equal to an average general estimation of the export of HUFA by emerging aquatic insects. Therefore, odonates appeared to be a quantitatively and qualitatively important conduit of aquatic productivity to forest-steppe ecosystem

Characteristics of Fatty Acid Composition of Gammarus lacustris Inhabiting Lakes with and without Fish

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.—The effect of a biotic factor—the presence of predatory fish in water—on the composition and content of fatty acids in crustaceans was studied in the populations of the lake amphipod Gammarus lacustris from two lakes with fish and three lakes without fish. It was found that, at an overall increase in the quantity and quality of food resources (namely, increase in the content of eicosapentaenoic acid and docosahexaenoic acid (DHA) in the biomass), the relative rate of DHA accumulation in gammarids in the lakes without fish is higher than in the lake with fish

Characteristics of Fatty Acid Composition of Gammarus lacustris Inhabiting Lakes with and without Fish

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.—The effect of a biotic factor—the presence of predatory fish in water—on the composition and content of fatty acids in crustaceans was studied in the populations of the lake amphipod Gammarus lacustris from two lakes with fish and three lakes without fish. It was found that, at an overall increase in the quantity and quality of food resources (namely, increase in the content of eicosapentaenoic acid and docosahexaenoic acid (DHA) in the biomass), the relative rate of DHA accumulation in gammarids in the lakes without fish is higher than in the lake with fish