Larval fish

Greater ecosystem diversity generally results in greater fish diversity. It follows that areas of greater ecosystem diversity would also exhibit greater larval fish diversity during recruitment events. To test the idea that larval fish would be more diverse in areas with greater ecosystem diversity, two sites on Bonaire, Netherlands Antilles were selected for study based on the amount of ecosystem diversity in each area. At Lac Cai, on the windward side of Bonaire, there are fringing reefs, a small barrier reef, seagrass beds, sand flats, and a mangrove lined bay. On the leeward side of the island in front of Kralendijk, the habitat is predominately fringing reef and sand flats. Three collection methods (plankton tows, light traps, and dip netting) were used to test my hypothesis that larval fish diversity at Lac Cai will be greater than that in front of Kralendijk due to greater ecosystem level diversity at Lac Cai. Simpson’s index of diversity (1-D) for Lac Cai (range 0.827 to 0.829) was significantly higher (one-tailed t-test assuming equal variance, p = 0.007, α = 0.05) than the values at Kralendijk (range 0.615 to 0.664) indicating that higher ecosystem diversity does result in higher larval fish diversity

This student research was retrieved from Physis: Journal of Marine Science IV (Fall 2008)19: 19-24 from CIEE Bonaire.

Coral reef fish larvae use sound to find suitable habitat during their vital settlement stage. Yet boat noise, which can cause stress and avoidance behaviour, and may cause masking via reduction of perceptual space, is common around coral islands and continental shelf habitats due to boat activity associated with fishing, tourism and transport of passengers and cargo. In a choice chamber experiment with settlement-stage coral reef fish larvae of the species Apogon doryssa, the directional responses of larvae were tested to 5 different noise types: Reef, Reef+Boat, Ocean, Ocean+Boat and White noise. The results showed that 69% of fish swam towards Reef playback compared with only 56% during Reef+Boat playback, while 44% of fish larvae moved away from Reef+Boat playback compared to only 8% during Reef playback. Significant directional responses were not observed during White noise, Ocean noise or Ocean+Boat noise playback. Overall, this study suggests that anthropogenic noise could have a disruptive effect on the response of fish larvae to natural reef sound, with implications for settlement and population dynamics in coral reef habitats disturbed by boat traffic.