Larvae and adult slope settlement of the reef coral Favia gravida in Porto Seguro reefs, Bahia, Brasil

Abstract

A successful reproduction is the first step in coral larvae recruitment on the reefs. Substrate types, as well as its orientation may affect coral recruitment, growth and survival rates. The current study was made at Porto Seguro, BA, Brasil, and aimed to observe planulation pattern, verifying the settlement preference of larvae on three different substrate slopes - horizontal, vertical and inclinated (45o) and evaluate the slope preference of Favia gravida adult colonies in different reefs of Porto Seguro, BA. Adult colonies were taken to aquariums and observed until planulation. Recently released larvae were transferred for aquariums with recruitment plates. These plates were examined after the 21st day of planulation. Porto Seguro most common reef types were sampled regarding adults occurrence: “coastal reefs”, the top of a patch reef or a reef flat, and the internal wall of a large lagoon inside Recife de Fora. Colonies slope were measured using a graduated arc and a float or weight (for negative positioned colonies) placed at the base of each colony, comprising a total of 540 colonies, 180 in each reef sampled. The larvae did not present a preference for substrate slope. Since adult colonies were commonly found at slightly steep upper surfaces, it is suggested that differential mortality may have happened with larvae in other surfaces. As Favia gravida larvae did not present strict slope preferences, and based on the knowledge that adults tend to occur at moderate steep surfaces, the results suggest this is the most suitable orientation for recruit introduction in Porto Seguro reefs in rehabilitation activities of degraded environmental, to certify most recruits survivorship in long term.