Growth and Production ofBullia Rhodostomaon an Open Sandy Beach in Algoa Bay

Abstract

The plough shell, Bullia rhodostoma (Mollusca: Gastropoda), has been studied on an open sandy beach where it is a common scavenger. Samples taken over a year indicate hatching of young individuals from December to February. They reach a length of about 10 mm after 1 year and 40 mm after 10 years. The von Bertalanffy growth equation is L 1 = 47 (1-e-<>• 1 •(t+o. 23 l) and the annual mortality rate is 0,79. Mean decalcified dry biomass is 209 mg m-2 and production by growth 189 mg m-2 y-1 giving a P/B of 0,9. Most production by adults(> 15 mm shell length) goes into reproduction, particularly in the females which grow larger than the males. Production by reproduction is estimated to be about 135 mg m-2 y-1 • Average calorific values are 19,04 kJ g-1 dry tissue

Age, growth and mortality inBuccinanops globulosus(Gastropoda: Nassariidae) from Golfo Nuevo (Argentina)

“…The von Bertalanffy growth curve has been previously used for other populations of B. globulosus (Narvarte 2006;Narvarte et al 2008) and in other species of nassariids, e.g. B. rhodostoma and N. reticulatus (McLachlan et al 1979;Chatzinikolaou & Richardson 2007). In the present study, asymptotic length ranged from 36 to 40 mm, 8 years being the theoretical age at which the asymptotic shell length is achieved.…”