Indications of sodium,chloride, and water exchange across the gills of the striped dogfish Poroderma africanum

The ecology of a large sandy beach at Calangute, Goa, Central West India over a 22-month period is described from the point of view of changes in the distribution and abundance of the macrofauna, and of the physical environment of the beach; the dominant effect of the annual monsoon is clearly shown. The results from Calangute are compared with a nearby beach (Colva) and from earlier studies in Southern India. The biology of the dominant wedge-clam Donax incarnatus Gmelin is described, in particular its more rapid breeding-cycle and smaller size at Calangute, compared with other populations studied. The annual production of D. incarnatus has been calculated as 14.7 kcal/m²/year, and has been shown to be relatively low in comparison with other bivalve populations, due to high mortality and the extensive environmental disruption caused by the annual monsoon. It is suggested that the conditions at Calangute are most suitable for settlement, and that the small size of D. incarnatus here is related to the short life span of 6 to 7 months of all individuals.