CHANGES IN VOLUME, BIOMASS, AND FATTY ACIDS OF DEVELOPING EGGS IN NAUTICARIS MAGELLANICA (DECAPODA: CARIDEA): A LATITUDINAL COMPARISON

Abstract

ABSTRACT The hippolytid shrimp Nauticaris magellanica, with a known geographical distribution covering approximately 35° of latitude, was selected to conduct a latitudinal comparison regarding volume, biomass, and fatty acid changes during embryogenesis. Ovigerous females were collected from populations in northern (Guanaqucros) and central-southern Chile (Metri and Putemun). Recently produced eggs from the 3 populations sampled were similar in size (ranging from 0.031-0.038 mm'). Embryos close to hatching, however, were considerably larger in central-southern Chile (Metri: 0.072 mm'; Putemun: 0.091 mm') compared with those from Guanaqueros (0.054 mm'). Egg volume increase during the incubation period varied between 74% (Guanaqueros) and 160% (Putemun). Wet mass and water content of embryos increased, while dry and ash mass decreased during embryogenesis. Analyses of fatty acids revealed similar results for eggs from the 3 study sites and different developmental stages. The overall utilization of fatty acids, however, was elevated in embryos from the most southern location (Putemun) compared with that found in embryos from the other sampling sites. Main fatty acids of eggs and newly hatched larvae were the polyunsaturates 20:5 (n-3) and 22:6 (n-3), and the saturate 16:0, comprising 21, 16, and 15%, respectively, of the total. The pattern of fatty acid utilization during embryogenesis is characterized by a sharp decline of the 16:1 (n-7) fatty acid. Our results confirm a latitudinal cline in egg volume in N. magellanica. The differences observed among populations may be attributed, however, to differences in the ambient conditions (e.g., temperature, salinity, feeding) of the habitats rather than simply to its northern and southern location. In addition, the lipid biochemistry of developing eggs seems to be unaffected by latitude.