Chemical suppression of feeding in larval weakfish (Cynoscion regalis) by trochophores of the serpulid polychaeteHydroides dianthus.

We studied the effect of exudates from trochophore larvae of the polychaeteHydroides dianthus on feeding in larval weakfish (Cynoscion regalis). Laboratory prey consisted ofH. dianthus trochophores and/or comparably sized rotifers (Brachionus plicatilis). When experiments were conducted in filtered seawater, ingestion of rotifers was always greater than ingestion of trochophores. However, consumption of rotifers was depressed when water fromH. dianthus cultures (=trochophore water) was the experimental medium. The same effect was noted whether we added trochophore water from polychaete cultures that were two or five days postfertilization. However, no effect was noted when we used water from rotifer cultures. We concluded thatH. dianthus trochophores release a water-soluble compound that inhibits feeding in weakfish larvae.