1:45 PM - 2:10 PM
[ACG38-01] Larval dispersal ecology of anemonefish: its association with hydrodynamics
★Invited Papers
Keywords:Coral reef, Fish, Larval dispersal, Metapopulation, Population genetics
Many marine species have life cycles with a pelagic larval phase that undergoes dispersal among habitat patches, and a benthic adult phase that occurs in discrete habitat patches after larval settlement. Marine larvae are subjected to oceanographic processes that transport them at varying distances from their original birthplace. The application of genetic parentage analysis to marine systems have revealed the spatial scale of dispersal and self-recruitment in coral reef fishes. However, few studies have investigated the influence of coastline types (e.g., bay vs. open coast) on marine larval dispersal.
To see association between larval dispersal, coastline types, and hydrodynamics, I utilized a combined approach of field survey, population genetics and biophysical modeling to infer larval dispersal of two anemonefish species (Amphiprion frenatus and Amphiprion perideraion) in a semi-closed bay and open coast in the Philippines. I expect that a bay or lagoon generally enhances the retention of larvae, while larvae are more likely to be flushed by strong currents in an open coast.
Field observation in a semi-closed bay found that their local abundance was related to habitat size and the presence of other anemonefish species, but patch isolation within the study area was not significant for both species. This result was confirmed by genetic parentage analysis showing there was no self-recruitment (0%) of juveniles in the semi-closed bay and no dispersal connectivity within the study area contrary to my expectation. Meanwhile, parentage analysis for anemonefish populations in the open coast revealed that self-recruitment was 14-15% for recruited juveniles. Comparisons of parentage analysis results between the two sites indicated lower estimates of self-recruitment in the semi-closed bay (0%) than in the open coast (14–15%). The result was consistent with biophysical dispersal simulations predicting lower LR and self- recruitment in the semi-closed bay (0.4% and 19%) compared to the open coast (2.9% and 38%). This dispersal modeling showed that cross-shore currents toward offshore were much stronger around the semi-closed bay and were negatively correlated with LR and self-recruitment. Our results highlight importance of hydrodynamics on larval dispersal and recruitment and difficulty in predicting self-recruitment from coastline type alone.
To see association between larval dispersal, coastline types, and hydrodynamics, I utilized a combined approach of field survey, population genetics and biophysical modeling to infer larval dispersal of two anemonefish species (Amphiprion frenatus and Amphiprion perideraion) in a semi-closed bay and open coast in the Philippines. I expect that a bay or lagoon generally enhances the retention of larvae, while larvae are more likely to be flushed by strong currents in an open coast.
Field observation in a semi-closed bay found that their local abundance was related to habitat size and the presence of other anemonefish species, but patch isolation within the study area was not significant for both species. This result was confirmed by genetic parentage analysis showing there was no self-recruitment (0%) of juveniles in the semi-closed bay and no dispersal connectivity within the study area contrary to my expectation. Meanwhile, parentage analysis for anemonefish populations in the open coast revealed that self-recruitment was 14-15% for recruited juveniles. Comparisons of parentage analysis results between the two sites indicated lower estimates of self-recruitment in the semi-closed bay (0%) than in the open coast (14–15%). The result was consistent with biophysical dispersal simulations predicting lower LR and self- recruitment in the semi-closed bay (0.4% and 19%) compared to the open coast (2.9% and 38%). This dispersal modeling showed that cross-shore currents toward offshore were much stronger around the semi-closed bay and were negatively correlated with LR and self-recruitment. Our results highlight importance of hydrodynamics on larval dispersal and recruitment and difficulty in predicting self-recruitment from coastline type alone.