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Forskningsartikel2013Vetenskapligt granskad

Cross-ecosystem differences in lipid composition and growth limitation of a benthic generalist consumer

Lau, Danny C P; Goedkoop, Willem; Vrede, Tobias

Sammanfattning

In a field study, we analyzed the fatty acid (FA) composition of the benthic generalist Asellus aquaticus collected from boreal lakes, ponds, and streams across gradients in ambient nutrient levels. In laboratory feeding experiments, we tested the diet-quality and seasonal effects on somatic growth and FAs of spring-and autumn-collected Asellus that were fed four different diets containing increasing concentrations of polyunsaturated FAs (PUFA): conditioned leaf litter, algal flakes, mixed litter and algal flakes (Mixed), or Mixed plus fish-food flakes. Ambient nutrients were strong determinants of FA variation of field Asellus, explaining > 44% in total. The ratios of eicosapentaenoic acid (EPA) to total FAs, EPA: omega 3, and omega 3 : omega 6 of Asellus increased up to four times with increasing trophic state and decreasing humic matter content, likely because dietary omega 3 FAs were more prevalent in benthic habitats of eutrophic than of oligotrophic systems. In the feeding trials, growth of Asellus collected in both seasons was markedly lower on leaf litter than on higher PUFA diets. However, autumn-collected Asellus fed a Mixed or Mixed+fish-food diet grew 3-10 times faster, but retained < 50% EPA and PUFA than spring counterparts. Asellus optimized PUFA accumulation in spring but somatic growth in autumn. Our field survey suggests ambient nutrient concentrations modify dietary PUFA supply from basal resources, while laboratory studies show that growth response and PUFA accumulation of Asellus differ between seasons, likely due to its season-specific physiological status and diet quality. An increase in nutrients will release benthic consumers from growth limitation and favor more efficient trophic transfer.

Nyckelord

Fatty acids, growth, isopod, lakes, nutrients

Publicerad i

Limnology and Oceanography
2013, Volym: 58, nummer: 4, sidor: 1149-1164 Utgivare: AMER SOC LIMNOLOGY OCEANOGRAPHY