Indirect effects of an ectoparasite reduce successful establishment of a damselfish at settlement

摘要: Summary 1. The sublethal impact of parasites on host behaviour and the mechanism linking them to population level effects remain largely unquantified. On Great Barrier Reef, juvenile gnathiid isopods (mobile ectoparasites) are one most common ectoparasites fishes. Previous laboratory studies damselfishes suggest that a single can kill settlement-stage larvae very young juveniles, while repeated attacks affect growth damselfish. Nothing, however, is known how gnathiids performance, survival settlement stage fishes in wild. 2. We sampled juveniles damselfish Pomacentrus amboinensis for tested effect (Gnathia auresmaculosa) laboratory. We also this swimming oxygen consumption, successful establishment wild larvae. 3. Of fish at dawn, 3·5% had attached; other times day, no gnathiids. In laboratory, (79%) remained attached up 6 h all survived exposure gnathiid. 4. When pairs double-lane swim chamber, previously been fed by ceased first 77% trials lower critical speed compared not exposed gnathiid. Previously parasitized 35% higher consumption rate than did unexposed fish. When tagged were placed dead coral patches monitored, disappeared from reef 67% trials. 5. Our analysis indicates ectoparasitic isopod significantly decreases performance P. their persistence reef. Gnathiids, affecting may therefore indirectly settlement, transitional Unsuccessful likely increases interactions settling with predators thus contribute high mortality observed time.