Haemolymph parameter changes in the South African Mooi River crab Potamonautes warreni during prolonged starvation

Animals in the wild are constrained by food resources. To understand the severity of starvation events on their biology, starvation in all its manifestations must be documented. Male Potamonautes warreni Calman crabs were collected live from the Mooi River, near Potchefstroom, South Africa, in April 2009. One hundred-microlitre haemolymph samples were collected serially at a specially prepared site on the carapace of each of the fed and starved crabs, and haemocyanin, D-glucose, chloride, calcium and pH were analysed. After six weeks' starvation, D-glucose had decreased by 400% and haemocyanin by more than 55% in starved crabs. Chloride concentration decreased continuously during the six weeks from 316.0 (SE 5.9) to 282 (SE 6.7) mmol l(-1) and from 301.0 (SE 7.9) to 266.0 (SE 3.6) mmol l(-1) in fed and starved crabs, respectively. Calcium concentration and pH decreased in fed crabs, whereas calcium concentration increased and haemolymph pH decreased in starved crabs. Possible reasons for changes in haemolymph parameters in fed and starved crabs are discussed.