Feeding
behaviour during brooding in the oyster Ostrea chilensis: gut retention time
in adults and larvae and potential use of larval faeces by adults
O.R. Chaparro, C.J. Soto, R.J. Thompson, I.I.
Concha-2002
Marine Ecology Progress Series, 222: 119-129
(from Current Contents)
Abstract :
The brooded larva of Ostrea chilensis is not an
obligate lecithotroph, as has often been supposed, because it removes
particles from the mantle cavity of the parent oyster. The ingestion of
exogenous particles by the larva becomes apparent when the shell length of
the veliger is approximately 290 mum, the same stage at which the velar
ciliature is also visible for the first time. Experiments using red plastic
marker particles showed that gut retention time in brooding oysters was
significantly greater (10 to 11 h) than in non-brooding oysters (8 h),
providing a mechanism for more efficient use of the ingested food. Although
there was no significant difference in gut retention time between oysters
brooding early and late larval stages, the late brooders eliminated most of
the faeces earlier than the early brooders, Experiments using C-14-labelled
algae demonstrated a shorter gut retention time in the larva (6 h) than in
the non-brooding adult (10 h). Faeces from larvae contained relatively more
chlorophyll a and less phaeopigment than faeces from brooding adults. The
data suggest that the digestive system of the larva is much less efficient
than that of the adult. Following the introduction of larvae previously fed
C-14-labelled algae into the pallial cavity of the brooding parent, the
radiolabel was detected in the faeces of the adult, suggesting that the
parent may ingest faeces produced by the larvae. The increase in gut
retention time by the adult during the brooding period and the ingestion of
larval faeces compensate for the high energy costs associated with the
brooding process.
(Univ Austral Chile, Inst Biol Marina Dr Jurgen
Winter, Casilla 567, Valdivia, Chile, e-mail: ochaparr@mercurio.uach.cl)