Differential reproductive investment in females of Lithodes santolla (Decapoda: Anomura) from different regions of southern South America

The southern king crab Lithodes santolla experiences low temperatures and unpredictable food conditions, and is under variable fishing pressure. To compare the reproductive investment of females, crabs were captured from three sites (Beagle Channel 55°S, Tierra del Fuego Atlantic coast 52-54°S and San Jorge Gulf 45-47°S). Fecundity, water and lipid contents were measured in midgut gland, ovary and muscle. To assess the maternal investment in the offspring, egg masses were analysed on lipid, protein, water and inorganic matter contents, egg volume and embryo size. Although fecundity was similar among sites, San Jorge Gulf females showed higher water and lower lipid contents in somatic and reproductive organs. The egg mass energy reserves varied among sites, showing the highest lipid values in the Beagle Channel, and the highest protein and inorganic matter content in San Jorge Gulf. Though water content was similar, egg volume and embryo size were higher in San Jorge Gulf. Moreover, maternal size did not correlate with egg volume, embryo size or lipid, protein and inorganic matter content of the eggs. This study suggests that reproductive investment of L. santolla varies among regions exposed to different environmental conditions, such as the quality of food available, denoting a female compensatory mechanism.