Alexander V. Ageev

Is the Fatty Acid Composition of Freshwater Zoobenthic Invertebrates Controlled by Phylogenetic or Trophic Factors

We studied the fatty acid (FA) content and composition of ten zoobenthic species of several taxonomic groups from different freshwater bodies. Special attention was paid to essential polyunsaturated fatty acids, eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3), and arachidonic acid (ARA, 20:4n-6); and the n-3/n-6 and DHA/ARA ratios, which are important for consumers of higher trophic levels, i.e., fish. The content and ratios of these FA varied significantly in the studied zoobenthic species, consequently, the invertebrates were of different nutritional quality for fish. Eulimnogammarus viridis (Crustacea) and Dendrocoelopsis sp. (Turbellaria) had the highest nutrition value for fish concerning the content of EPA and DHA and n-3/n-6 and DHA/ARA ratios. Using canonical correspondence analysis we compared the FA profiles of species of the studied taxa taking into account their feeding strategies and habitats. We gained evidence that feeding strategy is of importance to determine fatty acid profiles of zoobenthic species. However, the phylogenetic position of the zoobenthic species is also responsible and may result in a similar fatty acid composition even if species or populations inhabit different water bodies or have different feeding strategies.

Influence of anthropogenic pollution on content of essential polyunsaturated fatty acids in links of food chain of river ecosystem

In the course of monthly sampling in 2008–2010, two regions of the littoral of the Yenisei river were compared. One of these regions (conventionally pure) was situated upstream of Krasnoyarsk, while the other (conventionally polluted) was downstream of Krasnoyarsk. The concentrations of heavy metals, oil products, phenols, biogenic elements and essential polyunsaturated fatty acids (PUFAs) in various components of the river ecosystem were determined. It was discovered that the anthropogenic pollution causes a decrease in the resources of essential PUFA in the biomass of the upper links of the food chain of the river ecosystem.

Production of polyunsaturated fatty acids by zoobenthos in rivers with contrasting temperatures.

308 In the last decade, one of the most urgent tasks of aquatic ecology is the study of the influence of climate change on the functioning of aquatic ecosystems [1]. Global warming causes changes in the species compo sition of aquatic communities, which may be accom panied by changes not only in the quantity but also in the quality of production of aquatic ecosystems. For example, it was found that the zooplankton biomass in the cold lakes contains much more long chain poly unsaturated fatty acids (PUFA) of the omega 3 family (eicosapentaenoic acid (20:5n 3, EPA) and particu larly docosahexaenoic acid (22:6n 3, DHA)) as com pared to the warm lakes [2]. It is known that DHA is an essential component of cell membranes of the nerve tissue and retina of vertebrates and its deficiency in food suppresses the growth and development of fish [3, 4]. The influence of climate warming on the production of EPA and DHA by the zoobenthos, which is the main food of fish in fast flowing rivers remains virtually unstudied.

Seasonal changes in the standing stock of essential polyunsaturated fatty acids in the biomass of phyto- and zoobenthos on a littoral station of the Yenisei River.

In the past decade, it was shown that polyunsaturated fatty acids (PUFAs) of the ω 3 family, primarily, eicosapentaenoic ( 20:5 ω 3 , EPA) and docosahexaenoic ( 22:6 ω 3 , DHA) acids, play a key role in the regulation of the cardiovascular system and other pivotal physiological and biochemical processes in humans and animals [1, 2]. These acids are essential, because humans and the majority of animals are not able to synthesize them in sufficient amounts and must receive them with food. Today, a number of foreign dietitian organizations have introduced the norms of daily consumption of PUFAs for population. In the biosphere, EPA and DHA are synthesized most effectively by microalgae. Therefore, the main source of these essential PUFAs are aquatic ecosystems. Because PUFAs pass the trophic chain algae → invertebrates → fish before getting to humans, the assessment of the standing stock of essential PUFAs in various aquatic ecosystems [2] and the efficiency of their passage along the trophic chain is a topical problem. We studied seasonal changes in the content of EPA and DHA in the biomass of primary producers (phytobenthos) and primary consumers (zoobenthos) at the littoral station on the Yenisei River upstream of Krasnoyarsk. Samples of zoobenthos were taken with the use of a kick-bottom sampler at a depth of at most 0.5 m after roiling benthic sediments (pebbles). A kick-bottom sampler is a frame ( 40 × 35 cm) with a net (opening, 40 × 40 cm; mesh, 0.25 mm) directed downstream. For quantitative estimation of the phytobenthos (phytoperiphyton) biomass, pebbles were taken from a frame ( 10 × 10 cm) fixed on the bottom, from which all biofouling organisms were brushed into a certain volume of water.