Reproduction in the brine shrimp Artemia Leach, 1819 (Branchiopoda, Anostraca) from South India: Laboratory cross fertility tests and mating behaviour

Abstract. The brine shrimp Artemia is an inhabitant of hypersaline environments and has been used to study primary reproductive traits and mating behaviour together with the degrees of divergence among populations. Intrapopulation experimental crosses and cross-fertility tests were evaluated in four populations from coastal and inland environments of South India, and in a reference sample of A. franciscana (San Francisco Bay -SFB, U.S.A). Crosses were fertile with the production of live nauplii and cysts. Significant variations were observed among the populations studied in fecundity (e.g. total offspring, brood size). A reproductive switch from ovoviviparity to oviparity was observed, especially in crosses between inland populations with the reference strain. Differences between the South Indian samples and SFB were significant-for the total number of nauplii, percentage of encysted brood and broods per female. A peculiar pattern of male-male mating was observed, wherein the ratio of males was higher than females. About 70% of the orientation movements of the males were directed towards other males

Induced thermal stress on serotonin levels in the blue swimmer crab, Portunus pelagicus

The temperature of habitat water has a drastic influence on the behavioral, physiological and biochemical mechanisms of crustaceans. Hyperglycemia is a typical response of many aquatic animals to harmful physical and chemical environmental changes. In crustaceans increased circulating crustacean hyperglycemic hormone (CHH) and hyperglycemia are reported to occur following exposure to several environmental stress. The biogenic amine, serotonin has been found to modulate the CHH levels and oxidation of serotonin into its metabolites is catalysed by monoamine oxidase. The blue swimmer crab, Portunus pelagicus is a dominant intertidal species utilized throughout the indo-pacific region and is a particularly important species of Palk bay. It has high nutritional value and delicious taste and hence their requirements of capture and cultivation of this species are constantly increasing. This species experiences varying and increasing temperature levels as it resides in an higher intertidal zone of Thondi coast. The present study examines the effect of thermal stress on the levels of serotonin and crustacean hyperglycemic hormone in the hemolymph of P. pelagicus and analyzes the effect of the monoamine oxidase inhibitor, pargyline on serotonin and CHH level after thermal stress. The results showed increased levels of glucose, CHH and serotonin on exposure to 26 °C in control animals. Pargyline injected crabs showed highly significant increase in the levels of CHH and serotonin on every 2 °C increase or decrease in temperature. A greater CHH level of 268.86±2.87 fmol/ml and a greater serotonin level of 177.69±10.10 ng/ml was observed at 24 °C. This could be due to the effect of in maintaining the level of serotonin in the hemolymph and preventing its oxidation, which in turn induces hyperglycemia by releasing CHH into hemolymph. Thus, the study demonstrates the effect of thermal stress on the hemolymph metabolites studied and the role of pargyline in elevating the levels of serotonin and CHH on thermal stress in the blue swimmer crab, P. pelagicus