S. Pouvreau et al., In situ suspension feeding behaviour of the pearl oyster, Pinctada margaritifera: combined effects of body size and weather-related seston composition, AQUACULTURE, 181(1-2), 2000, pp. 91-113
In situ clearance rate (CR) and biodeposition of the black pearl oyster, Pi
nctada margaritifera, were followed during several field experiments from 1
996 to 1998 in the lagoon of Takapoto. Serial measurements of total particu
late matter (TPM, mg l(-1)), particulate inorganic matter (PLM, mg l(-1)),
and particulate organic matter (POM, mg l(-1)) were related to meteorologic
al conditions, especially wind speed. As a general case, POM and PLM increa
sed with wind speed. Nevertheless, PLM increased faster than POM so that th
e organic content (OC, %) of the TPM decreased progressively when wind spee
d increased. These TPM variations induced direct changes in feeding process
es of P. margaritifera. CR (l h(-1)) averaged 22 l h(-1) for a pearl oyster
of 1 g dry tissue weight and varied with POM, PLM and dry tissue weight (W
, g) according to the following equation: CR = 26.96 (PIM-0.42POMW0.61)-W-0
.96. This clearance activity appeared to be the highest of those mentioned
for bivalve species in their natural habitats. Pseudofaecal (PF, mg h(-1))
production started for very low PIM load (i.e., 0.17 mg l(-1))and POM load
(i.e., 0.28 mg l(-1))in water and followed the equation: PF = 32.6(POM - 0.
28)(PIM - 0.17)W-0.77. In other bivalve species, PF are generally observed
for higher PIM or POM levels. These PF were mainly constituted of mineral m
atter (more than 80% in weight). Faecal production (F, mg h(-1)) increased
with seston load and reached progressively a plateau (i.e., maximal intesti
nal transit time) as shown by the equation describing the faecal biodeposit
ion F = 20 W-0.49(1 - e(-0.66) (TPM)). The quantity and the composition of
the faecal biodeposit were in a range commonly found in literature. This wo
rk confirms, by in situ experiments, previous results obtained in laborator
y and especially that P. margaritifera has developed a trophic strategy whi
ch consists of processing large amounts of water to gain sufficient energy
in poor waters. But this work also showed that meteorological conditions ha
ve indirect influences on feeding processes of pearl oyster by modifying si
gnificantly the concentration and the composition of seston. (C) 2000 Elsev
ier Science B.V. All rights reserved.