Seasonal variations in size, biomass, and elemental composition (CHN) of Halicarcinus planatus (Brachyura, Hymenosomatidae) larvae from the Beagle Channel, southern South America

MARIANO J. DIEZ; EDUARDO D. SPIVAK; KLAUS ANGER; GUSTAVO A. LOVRICH

JOURNAL OF CRUSTACEAN BIOLOGY

CRUSTACEAN SOC

Año: 2012 vol. 32 p. 973 - 983

0278-0372

The crab Halicarcinus planatus is the only member of the familiy Hymenosomatidae thatinhabits the southern tip of South America, and it is the only decapod species that reproducestwice a year in the Beagle Channel. In this study, we analysed seasonal variations indevelopment duration, body size, biomass (dry weight), and elemental composition (CHN) oflarvae from a population living at the southernmost limit of the species geographic range.Compared to offspring produced in December (early summer), larvae released in August (latewinter) were on average larger and heavier, and they showed a higher carbon content(suggesting a larger lipid fraction). This pattern of intraspecific variation in larval size andbiomass corresponds with minimum primary productivity in Subantarctic regions duringwinter, suggesting that large winter eggs may represent a reproductive adaptation to a regularpattern of variation in nutritional conditions, including food limitation in winter. As anadditional or alternative explanation, also strong salinity fluctuations occurring in summermight reduce larval quality in the December cohort. In conclusion, seasonal variation inlarval size and biomass may be related to variations in nutritional and/or physical factors.