Abstract

The distribution of fishes is determined by different factors that are regulated mainly by small and big scale movements during its life cycle. These movements can go from daily changes of habitat to permanent movements between systems. Migrations within short distances can be directly related to feeding dynamics, refugee and to avoid potential predators, also to temporary patterns such as daily light cycles, annual cycles of seasonal changes, and tidal changes in coastal areas. The aim of the present study is to evaluate the daily light cycle variation in fish assemblages between places with different habitat types (mudflats and seagrass beds). The study was conducted from January to November 2006 in the Celestún lagoon, a protected area in the state of Yucatan, located at the southeast of Mexico. The fish captures were obtained using a beach seine in two different habitats for periods lasting 8 hours. A total of 55 fish species were recorded comprising a total of 3,897 organisms. From these, 30% represented the day assemblage, 42% twilight and 28% nocturne. The habitat that registered the highest density was seagrass beds with 55%, while the mudflat had 45%. The highest species richness was registered during the night (43) and for the habitat with aquatic vegetation (48). The highest density was registered during the twilight and for the seagrass beds habitat, this is due to the fact that this areas offer refuge, protection and food to many juvenile fish species.

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