Fluctuation of fish eggs and larvae in coral reefs of Nha Trang bay and adjacent waters

Abstract

This paper presents the results of fish eggs and larvae surveyed in Nha Trang in 2003 & 2009. The samples were collected by using vertical ring net and surface plankton net. Composition of fish eggs and larvae was very diverse with more than 40 families of 10 orders, in which anchovies (Stolephorus spp), gobies (Gobiidae), herrings (Clupeidae) appeared with high percentage year round. The densities of fish larvae of some families of reef fishes such as parrot fishes (Scaridae), wrasses (Labridae), damselfishes (Pomacentridae) and surgeon fishes (Acanthuridae) were relatively low. The average density of the survey in 2003 was 477 ± 59 eggs and 267 ± 29 larvae per 100m3. The densities of fish eggs and larvae at each sampling site were high in all months, however there were no clear patterns of breeding grounds and seasons (f "fish egg" = 0.87 < fα =1.94 and f "fish larvae" = 1.80 < fα = 1.94). In coral reefs, the average density in July 2009 (1.437 ± 501 eggs and 97 ± 43 larvae per 100m3 respectively) was higher than that in October 2009 (677 ± 171 eggs and 59 ± 26 larvae per 100m3), and that on inner reefs (626 ± 113 eggs and 62 ± 19 larvae per 100m3 respectively) was lower than that on outer reefs (1.488 ± 513 eggs and 94 ± 46 larvae per 100m3). However, there were no significant differences of fish eggs and larvae between the sampling periods and between the inner and outer reefs (f "fish egg" = 2.05 < fα =4.13 and f "fish larvae" = 0.57 < fα = 4.13).