Changes in biomass, lipid, fatty acid and elemental composition during the abbreviated larval development of the subantarctic shrimp Campylonotus vagans

Abstract

Ontogenetic changes in biomass and chemical composition were studied in the laboratory during the abbreviated larval and early juvenile development of the caridean shrimp Campylonotus vagans from the subantarctic Beagle Channel, Argentina. At 7±0.5 °C, development from hatching to metamorphosis took about 44 days. The larvae started feeding on Artemia nauplii immediately after hatching, although larval resistance to starvation was high (average 18 days, maximum 29 days). Dry mass (DM), carbon (C), nitrogen (N) and hydrogen (H) contents increased about a fourfold from hatching to metamorphosis, while the C:N mass ratio increased from about 3.7 to 4.3. The protein and total lipid contents increased gradually from hatching to the first juvenile stage, the former from 190 to 640 ?g/individual, the latter from 37 to 95 ?g/individual. The lipid mass fraction was low throughout larval development (3–9% of DM), while the protein content was much higher and almost constant (30–40%). The dominating fatty acids were 18:1(n-9), 16:0, 20:5(n-3), 18:1(n-7), 18:3(n-3), 18:0, 16:1(n-7). Except for 20:5(n-3), these resulted mainly from food uptake (Artemia nauplii). Exuvial losses of C, H and N (all larval stages combined) accounted for only 7%, 1% and 1% of the initial values at hatching. In contrast, 37% of initial DM was lost. Partially food-independent (endotrophic) larval development is discussed as an adaptation to food scarcity at high latitudes, while the abbreviated planktotrophic larval development appears to be synchronised with seasonal peaks in primary production, allowing for an optimal resource exploitation in a food-limited environment.

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