GEOGRAPHIC DYNAMIC OF LIPID CONTENT LARVAE DAUBED SHANNY LEPTOCLINUS MACULATUS (FAMILY: STICHAEIDAE) FROM ISFJORDEN AND KONGSFJORDEN, SVALBARD

Svetlana A. Murzina¹, Stig Falk-Petersen², Jmrgen Berge³, Nina N. Nemova¹

¹ Institute of Biology, Karelian Research Centre RAS, Petrozavodsk, Russia e-mail: imagination@onego.ru

² Norwegian Polar Institute, Tromsm N-9296, Norway ³The University centre in Svalbard, Longyearbyen N-9171, Norway

Lipids for Arctic organisms very important as variant of adaptive behavior, pelagic larvae and fish feeding on Calanus ssp.

Daubed shanny Leptoclinus maculatus is among the dominating species of the epibenthic fauna of Arctic waters and thus play a significant role both as predators and prey in the Arctic ecosystem. The larvae are pelagic while the adults are bottom inhabitants. Pelagic larva is very common in pelagic biomass during whole summer season and they stay pelagic till 3 years old. Significant detail of L. maculatus larva is that it have ability to store lipids obtained from Calanus ssp. diet in particular part of the body called lipid sac situated on the ventral part of the body. Lipid sac as important body part have been investigated in several species of Antarctic fishes (DeVries, Eastman, 1977; Clarke et al., 1984; Friedrich, Hagen, 1994) and shown hot importance of it for adaptation, buoyancy and development in severe Antarctic conditions but no relevant works have been conducted about Arctic fishes. Storage, using and utilization of lipids in the larvae organisms appear high top interest as help to understanding of lipid dynamics in food web chain and food chain relationships, life cycle of larvae L.

The objective of this study is investigation of lipid classes and fatty acid spectrum qualitatively and quantitatively of larvae L. maculatus from Svalbard waters along the Northern-West coast of Spitsbergen from summer season.

Matherial and methods

The samples of larva L. maculatus was collected in Isfjorden(78⁰20'N 15⁰00'E), Kongsfjorden

(79⁰00’N 11°40’E) and outside of Kongsfjorden - V10 (78⁰95’N 08°81’E) station during summer 2007

(22-29 July) at stations with depth 50 m with pelagic trawling on board RV “Jan Mayen”. Weighed

samples (0.5-1.0 g) of lipid sac and flesh from same in length and weight parameters from fresh larvae were derived from fresh material as soon as possible after capture of the fish and homogenized (where conditions permitted) in 10 volumes (10 ml) of 96% ethyl alcohol mixed with 0.001% of the antioxidant ionol. Sample homogenates were placed in plastic vials and stored onboard in a cooling room at 4 °C until delivery to the laboratory. The material was then fixed in a solvent system of chloroform: methanol (2:1, v/v), and total lipids (TL) were extracted following the method of Folch et al. (1957).

Lipid class and fatty acid analysis

The material was then fixed in a solvent system of chloroform: methanol (2:1, v/v), and total lipids (TL) were extracted following the method of Folch et al. (1957). Individual lipid classes were identified as phospholipids (PL), triacylglycerols (TAG), cholesterol (CH), and wax esters (WE) by thin-layer chromatography. Their quantities were determined using the hydroxamate method (Sidorov et al., 1972b) and then spectrophotometry. Quantitative determination of CH was determined based on Engelbrecht et al. (1974) and spectrophotometry.

The fatty acid and alcohol compositions of the total lipid extracts and the lipid classes were analysed by gas-liquid chromatography.

For all lipid data One-way ANOVA was performed. Due to the robustness of the ANOVS we assume that all data are normal distributed with even homogeneity of variance.

Results

Larva L. maculatus is a very lipid-rich fish the main functions of it accumulation of storage and metabolic lipids and in addition to it obvious role in buoyancy. The composition of the total lipids from the oil sac and the flesh is presented in Table 1. The maximum lipid content was determined in larva lipid sac

from Kongsfjorden - 64,43% dry weight and minimum content in lipids sac from Isfjorden. The maximum lipid concentration noticed in larva muscle from Kongsfjorden and minimum outside of Kongsfjorden, deep station V10 - 27,95% and 24,48% dry weight. Triacylglicerols were dominant lipid compound in lipid sac and muscle: from 40,55 till 58,31% dry weight (from 93,36 till 89,72% sum lipids) and from 12,66 till 14,54% dry weight (from 54,62 till 45,33% sum lipids), respectively. The wax esters have not been occurred in lipid sac while in muscle composed a little content compare to triacylglicerols (Table 1). The same results were shown in Falk-Petersen with colleagues investigation (Falk-Petersen et al., 1986). Among polar lipids cholesterol (Chl) was dominant lipid component in muscle and totally absent as wax esters in lipid sac. The molar ration of Chl to phospholipids (PL) in muscle varied from 0,47 to 0,90 along the series: V10 station to Kongsfjorden via Isfjorden (Table 1). A high ratio in larvae muscle from V10 station out of Kondsfjorden was due to the fact that cholesterol regulates the fluidity of membrane and activation of membrane-connected enzymes. The main PL found in muscle and lipid sac were phosphotidylcholine (PC) and phosphotidylethanolamyne (PE), always they are dominant individual phospholipids in all studied organs and tissues of the fish (Velansky & Kostetsky, 2007). The ratio PC to PE reflects compensatory mechanisms that allow maintenance of physical-chemical membrane properties with changing temperatures (Kattner et al., 2007).

Table 1

Lipid class composition in muscle and lipid sac Leptoclinus maculatus larvae from Isfjorden, Kondsfjorden, V10 station from summer season (July, 2007)

The fatty acid composition of the lipid classes in the lipid sac and the flesh is presented in Table 2.

Table 2

Fatty acid (FA) composition (% FA) in muscle and lipid sac Leptoclinus maculatus larvae from Isfjorden, Kondsfjorden, V10 station from summer season (July, 2007) (% FA)

Acknowledgements: This work are supported by grands 08-04-98843rsever a from RFBR, 08-04-01140-a from RFBR, 08-04-01691 from RFBR, STATOIL ARCTOS Programm, University centre in Svalbard, Norwegian Polar Institute, The Scottish Association for Marine Science