Growth and production of <i>Donax sordidus</i> Hanley on an open sandy beach in Algoa Bay

Abstract

A population of Donax sordidus (Mollusca, Pelecypoda) has been studied for two years on an open sandy beach. There were summer and winter settlements each year with the former being larger. Growth was rapid, the animals reaching 20 mm length within one year. Few live longer than 17 months. Production averaged 168,7 mg dry matter m^-2y^-1and the steady stateP¯¯¯/B¯¯¯

was 1,30y^-1. Energy values averaged 17,84 kJg^-1dry tissue and had a seasonal cycle with maximum values before spawning.

'n Donax sordidus (Mollusca, Pelecypoda) bevolking is oor twee jaar op 'n oop sand strand bestudeer. Vestiging van larwes het in die somer en die winter plaasgevind met die somer vestiging die grootste. Groei was vinnig en die diere was 20 mm lank binne die eerste jaar. Min diere lewe langer as 17 maande. Produksie was gemiddeld 168,7 mg m^-2 j^-1 en die gemiddelde

P¯¯¯/B¯¯¯was 1,30y^-1. Energiewaardes was gemiddeld 17,84 kJg¹ droë weefsel en het n seisoenale siklus met maksimum waardes net voor kuitskieting.