S. A. Murzina

Gender specific reproductive strategies of an arctic key species (Boreogadus saida) and implications of climate change

The Arctic climate is changing at an unprecedented rate. What consequences this may have on the Arctic marine ecosystem depends to a large degree on how its species will respond both directly to elevated temperatures and more indirectly through ecological interactions. But despite an alarming recent warming of the Arctic with accompanying sea ice loss, reports evaluating ecological impacts of climate change in the Arctic remain sparse. Here, based upon a large-scale field study, we present basic new knowledge regarding the life history traits for one of the most important species in the entire Arctic, the polar cod (Boreogadus saida). Furthermore, by comparing regions of contrasting climatic influence (domains), we present evidence as to how its growth and reproductive success is impaired in the warmer of the two domains. As the future Arctic is predicted to resemble todays Atlantic domains, we forecast changes in growth and life history characteristics of polar cod that will lead to alteration of its role as an Arctic keystone species. This will in turn affect community dynamics and energy transfer in the entire Arctic food chain.

The effect of environmental conditions on the dynamics of fatty acids in juveniles of the Atlantic salmon (Salmo salar L.)

The dynamics of fatty acid composition have been studied in differently aged salmon juveniles (0+, 1+, 2+ parrs and 3+ smolts) inhabiting two biotopes of the Varzuga River (the White Sea basin) differing in ecological conditions. Differences in the levels of linoleic (18:2n-6), linolenic (18:3n-3), and oleic (18:1n-9) acids have been revealed. It has also been shown that 3+ smolts have an increased content of long-chain fatty acids—arachidonic (20:4n-6), eicosapentaenoic (20:5n-3), and docosahexaenoic (22:6n-3)—characteristic of the composition of marine-type lipids.

Lipid Status of the Two High Latitude Fish Species, Leptoclinus maculatus and Lumpenus fabricii

A comparative study of the lipid status (i.e., the total lipid and phospholipid concentrations and the percentage of fatty acids of the total lipids) of adult specimens of daubed shanny (Leptoclinus maculatus) from Svalbard waters (Isfjord) and slender eel blenny (Lumpenus fabricii) from the White Sea (Onega Bay and Tersky shore) was performed to study the metabolism and functions of lipids of these fishes in ontogeny and under various ecological conditions. Slender eel blenny from both areas of the White Sea were distinguished by a high level of sphingomyelin compared with the daubed shanny from Svalbard, and the amount of total phospholipids was higher in slender eel blenny from Onega Bay than in slender eel blenny from the Tersky shore. The extent of saturation and the signature of polyenic fatty acids varied according to the specific species of the Stichaeidae family under study. These results demonstrate the differences in the trophoecological and hydrobiological conditions of habitations of these species and highlighted the importance of considering certain trends in the lipid profiles of these fishes as specific features of the organization of the ecological and biochemical mechanisms of adaptation.

Lipid status of larvae and adults of the White Sea herring Clupea pallasii marisalbi Berg (Clupeiformes, Clupeidae)

37 The population of the White Sea herring Clupea pallasii marisalbi Berg (Clupeiformes, Clupeidae) is one of the closest forms of the Pacific herring and one of the most important commercially valuable fishes of the White Sea. The growth of the herring stock in recent years is due to its gradual recovery (after the death in the early 1960s) of the White Sea eelgrass, whose thickets serve as spawning and development sites of eggs as well as foraging and growth sites of her ring larvae and fries [1]. Biochemical studies on the White Sea herring are practically absent. However, such studies could help answer the question as to whether different groups of herring are characterized by biochemical heterogeneity. It is known that lipids play an important role in the formation of the bio chemical status of organisms. They are essential struc tural components of biological membranes, are involved in energy processes in cells and in the regula tion of biochemical reactions and physiological pro cesses, are the precursors of the biosynthesis of steroid hormones, etc. [2, 7].

Lipid content in the young-of-the-year sockeye salmon Oncorhynchus nerka during feeding migration (the Ozernaya River, Western Kamchatka)

235 Sockeye salmon Oncorhynchus nerka of Kam� chatka populations in comparison to other Pacific salmon differs in that it spends its freshwater period predominantly in lakes. Spawning grounds of sockeye salmon are situated both in lakes and in rivers flowing in or out of the lakes. Therefore, to reach a rearing lake juvenile sockeye salmon perform differently directed migrations as soon as in the first year of life. The direc� tion of migrations depends on the location of spawn� ing areas relative to the rearing lake. Before the escape to the lake youngoftheyear sockeye salmon accu� mulate in the river source in the zone of reverse flow (5, 6). Along with mass upstream migration, down� stream migration occurs in rivers flowing out of lakes (6, 7, 13). The youngoftheyear of sockeye salmon per� forming upstream and downstream migrations and those preparing for escape to the lake differ in body length, behavior, and feeding patterns. On the basis of these characteristics, they could be assigned to differ� ent phenotypic groups (6, 7). There are data on physi� ological and biochemical differentiation in the fish performing upstream and downstream migrations: Patterson et al. and Pon et al. (14, 15) demonstrated that the fry performing differently directed feeding migrations differ in swimming performance and in the content of oxidative enzymes. Depending on the direction, migrations may require considerable energy expenditures and there� fore may be accompanied by restructuring at the cellu� lar level, which are provided by lipids to a considerable extent. Individual classes of lipids perform various functions in the body. Each of these functions has a determinative significance in a certain ecological- physiological situation (10). Therefore, lipids are a major index of biochemical differentiation. This determined the aim of the present study, namely, com� parative analysis of the content of lipids in sockeye salmon juveniles of the first year of life from different phenotypic groups in the period of feeding migration, in order to confirm the presence of these groups at the physiological-biochemical level.

Features in the Lipid Status of Two Generations of Fingerlings (0+) of Atlantic Salmon (Salmo salar L.) Inhabiting the Arenga River (Kola Peninsula)

The present research focused on determining the lipid status of salmon fingerlings (0+) in early development after dispersal form groups of spawning nests in biotopes of different hydrological conditions. The revealed qualitative and quantitative differences in the levels of phospholipids and fatty acids among two generations of Atlantic salmon fingerlings (0+) living in different biotopes of the Arenga River (a tributary of the Varzuga River) may be associated with the peculiarities of their genetically determined processes of the biosynthesis and modification of individual lipid classes and trophoecological factors (food spectrum, quality and availability of food objects, and hydrological regime). The research was organized to observe the dynamics of these developmental changes from ages 0+ to 2+.

Metabolic enzymes activity and histomorphology in the liver of whitefish (Coregonus lavaretus L.) and pike (Esox lucius L.) inhabiting a mineral contaminated lake

The effects of wastewater from a mining and ore-dressing mill on fish in Lake Kostomukshskoe, which is used as a cesspool of circulating water and for storage of industrial wastes produced by the Kostomuksha mining and ore-dressing mill in northwest Russia, were studied. The lake is characterized by heavy mineralization, high pH, elevated levels of K+, Li+, SO42−, NO2−, Cl−, Li, Mn, and Ni, and the presence of a fine-dispersed mechanical suspension. To assess the impact of contamination on fish and determine the mechanisms of their adaptation, we investigated the biochemical indices and histology of the liver of whitefish (Coregonus lavaretus L.) and pike (Esox lucius L.) inhabiting Lake Kostomukshskoe, downstream Lake Koyvas (64° 47′ 30° 59′), and Lake Kamennoe, which is located in a nature preserve and has not been affected by anthropogenic activity (64° 28′ 30° 13′). Changes were detected in the activity of metabolic enzymes (cytochrome c oxidase (COX), lactate dehydrogenase, and glucose-6-phosphate dehydrogenase) in the liver. Specifically, the COX activity in the liver of both fish species from the contaminated lake decreased, indicating a low level of aerobic metabolism. Lipid infiltration was the most visible and widespread change observed in the liver of both fish species; therefore, it can be considered a marker of such long-term contamination. Lesions in pike liver demonstrated a wider range of severity than in those of whitefish. In summary, metabolic enzyme activity and histomorphology of the liver of whitefish and pike differed among lakes in a species-specific manner. The changes in enzyme activity and histomorphological alterations in fish that were observed can be applied for evaluation of freshwater systems that may be subjected to mineral pollution.

Heterogeneity of lipids and fatty acids of fingerlings of Atlantic salmon Salmo salar L. different in weight and size

Lipid and fatty acid spectra have been investigated in fingerlings of Atlantic salmon distinguished by weight and length characteristics and degree of fatness. Heterogeneity in terms of fatty acids in the studied groups of fingerlings is shown which indicates the differences in the rates of biochemical reactions of synthesis and modification of lipids and fatty acids caused by phenotypic diversity. Specificities of the metabolic processes in the studied groups of salmon fingerlings are related to the qualitative variety of nutrition spectra and the availability of food in the biotope.

Lipids in the daubed shanny (Teleostei: Leptoclinus maculatus) in Svalbard waters

The daubed shanny, Leptoclinus maculatus, is a common fish species in Arctic and North Atlantic waters and has an important role in high-latitude ecosystems as a link between lower trophic levels and many fish, marine mammal and seabird species. Its biology and ecology have, however, remained largely unstudied. The primary aim of this study was to increase the knowledge about the daubed shanny by analysing total lipids, lipid-classes and the fatty acid composition of liver, muscle and female gonads in adults from the high Arctic archipelago of Svalbard. In female gonads, the triacylglycerols and wax esters in addition to cholesterol esters were dominant among the stored lipids. Triacylglycerols dominated in the liver, whereas structural lipids, such as phospholipids and cholesterols, were the most important lipids in muscles. Phosphatidylcholine and phosphatidylethanolamine were major phospholipids in all organs studied. The fatty acid spectrum of the investigated organs was characterized by a high amount of monounsaturated fatty acids, particularly in the liver. Polyunsaturated fatty acids, particularly 22:6(n-3) and 20:4(n-6), were prevalent in muscle tissues. The lipid and fatty acid spectra in the organs during this period of life are tightly connected with the activation of the liver metabolism and the storage of lipids in the developed female gonads. Lipid accumulation and distribution in gonads are transferred to optimal development of embryos and larvae in Arctic waters.

Effects of ecological conditions on lipid composition of the liver and muscles in the daubed shanny, Leptoclinus maculatus

A comparative study on the lipid composition of the liver and muscles has been performed in daubed shanny caught in summer (July) in Arctic waters at three different sites (biotopes) along the north-western coast of Spitsbergen. In marine organisms living at high latitudes, lipids play an especially important role, primarily as reserve substances and as a factor influencing adaptation to severe environmental conditions. Since the ecology of daubed shanny is poorly known, the data obtained may be considered novel.