Temperature-dependent lipid levels and components in polar and temperate eelpout (Zoarcidae)

Abstract

Total lipid content, lipid classes and fatty acid composition were analysed in tissues from two eelpout species fed on the same diet, the Antarctic Pachycara brachycephalum and the temperate Zoarces viviparus, with the aim of determining the role of lipids in fishes from different thermal habitats. The lipid content increased with decreasing temperature in the liver of both species, suggesting enhanced lipid storage under cold conditions. In P. brachycephalum, lipid composition in the liver and muscle was strongly dominated by triacylglycerols between 0 and 6 degrees C. In contrast, in the temperate species, lipid class composition changed with changes in the temperature. When acclimatized to 4 and 6 degrees C Z. viviparus not only displayed a shift to lipid anabolism and pronounced lipid storage, as indicated by high triacylglycerol levels, but also a shift to patterns of cold adaptation, as reflected by an increased content of polyunsaturated fatty acids in the lipid extract. Unsaturated fatty acids were also abundant in the Antarctic eelpout, but when compared to Z. viviparus at the same temperatures, the latter had significantly higher ratios of polyunsaturated to saturated fatty acid levels, whereas the Antarctic eelpout showed significantly higher ratios of monounsaturated to saturated fatty acid levels. High delta-15N values of the Antarctic eelpout reflect the high trophic level of this scavenger in the Weddell Sea food web. Stable carbon values suggest that lipid-enriched prey forms a major part of its diet. The strategy to accumulate storage lipids in the cold is interpreted to be adaptive behaviour at colder temperatures and during periods of irregular, pulsed food supply.

Evolutionary force in confamiliar marine vertebrates of different temperature realms: adaptive trends in zoarcid fish transcriptomes

“…The lipid fraction in liver of P. brachycephalum kept at 0°C is threefold higher than in Z. viviparus at habitat temperature [37], in line with the general finding that Antarctic species have high capacities for catabolism of fatty acids [38]. Furthermore, a recent study demonstrated relationships between preferred energy fuels and transcript levels of respective genes in P. brachycephalum [39].…”

Thermal acclimation in Antarctic fish: transcriptomic profiling of metabolic pathways

“…Successful cloning of the different PPARs demonstrated that P. brachycephalum expresses the same compounds of the PPAR signaling cascade as temperate eurythermal fish. Lipid accumulation in the cold found for the Antarctic eelpout (10) and for species in the suborder of the Notothenioidei (38) indicate the general preference for fatty acids as main energy stores in cold-adapted fishes. First, temperature-induced shifts in lipid degradation and synthesis pathways over time may provide intermediates sensed by the PPAR family of transcription factors.…”

Simulating climate change‐induced alterations in bioaccumulation of organic contaminants in an Arctic marine food web

“…Few published studies were available on possible changes in lipid fractions in the animals in changing climate. Roughly based on study by Brodte et al [36] on temperaturedependent lipid levels in polar and temperate eelpout (Pachycara brachycephalum and Zoarces viviparus [Zoarcidae]), a (linear) decrease was assumed in L of 5% per 8C increase in the present scenarios for poikilotherm aquatic fauna (i.e., no change in L was assumed for algae and kittiwake). No changes were assumed in the organisms' body volumes (V) in the present scenarios.…”