Solar ultraviolet (UV) is among the most important ecological factors shaping the composition of biota on the planet’s surface, including the upper layers of waterbodies. Inhabitants of dark environments recently evolving from surface organisms provide natural opportunities to study the evolutionary losses of UV adaptation mechanisms and better understand how those mechanisms function at the biochemical level. The ancient Lake Baikal is the only freshwater reservoir where deep-water fauna emerged, and its diverse endemic amphipods (Amphipoda, Crustacea) now inhabit the whole range from highly transparent littoral to dark depths of over 1600 m, which makes them a convenient model to study UV adaptation. With 10-day-long laboratory exposures, we show that adults of deep-water Baikal amphipods Ommatogammarus flavus and O. albinus indeed have high sensitivity to environmentally relevant UV levels in contrast to littoral species Eulimnogammarus cyaneus and E. verrucosus. The UV intolerance was more pronounced in deeper-dwelling O. albinus and was partially explainable by lower levels of carotenoids and carotenoid-binding proteins. Signs of oxidative stress were not found but UV-B specifically seemingly led to the accumulation of toxic compounds. Overall, the obtained results demonstrate that UV is an important factor limiting the distribution of deep-water amphipods into the littoral zone of Lake Baikal.

The fatty acid comparative essay of high aquatic plants: Typha latifolia L., Ceratophyllum demersum L. and Veronica anagallis-aquatica L. from water bodies of Baikalian region was carried out. For the first time this biochemical parameter of water form V. anagallis-aquatica was compared with that of coastal-water T. latifolia and submerged C. demersum. The fifteen individual molecules of fatty acids with a chain length from 12 to 22 carbon atoms have been identified by the method of gas liquid chromatography – mass spectrometry. The fatty acid composition of investigated species was different. Among the fatty acids saturated and unsaturated molecules was found, the most distributed fatty acids was saturated palmitic (С16:0), steric (С18:0) and unsaturated linoleic (С18:2 w6), α-linolenic (С18:3 w3). In total, the C16 and C18 acids in studied species accounted for 98%. Differences in the composition of fatty acids of the studied species are discussed from the standpoint of the characteristics of fatty acid metabolism depending on the habitat of plants and are considered as one of the mechanisms of their adaptation to late vegetation. Studies of the fatty acid composition of aquatic organisms contribute to the overall strategy of plant adaptation to changing environmental conditions and are important for the ecological and biochemical monitoring of the ecological status of water bodies.

Solar ultraviolet (UV) is among the most important ecological factors shaping the composition of biota on the planet surface, including upper layers of waterbodies. Inhabitants of dark environments recently descending from surface organisms provide natural opportunities to study the evolutionary losses of UV adaptation mechanisms and better understand how those mechanisms function at the biochemical level. Ancient Lake Baikal is the only freshwater reservoir, where deep-water fauna emerged, and its diverse endemic amphipods (Amphipoda, Crustacea) now inhabit the whole range from highly transparent littoral to dark depths of over 1600 m, which makes them a convenient model to study UV adaptation. Here we show that adults of deep-water Baikal amphipods Ommatogammarus flavus and O. albinus indeed have high sensitivity to environmentally relevant UV levels in contrast to littoral species Eulimnogammarus cyaneus and E. verrucosus. The UV intolerance was more pronounced in deeper-dwelling O. albinus and was explainable by lower levels of carotenoids and carotenoid-binding proteins. Signs of oxidative stress were not found but specifically UV-B seemingly led to accumulation of toxic compounds. Overall, the obtained results demonstrate that UV is an important factor limiting distribution of deep-water amphipods into the littoral zone of Lake Baikal.