Sucession of Fish Species in Artificial Reefs at a Coastal Island in Souh Brasillian Litoral

Abstract

The utilization of artificial structures placed in marine bottom for fish attraction date of long time. In the last 10 years artificial reefs has been used in brazillian coast under several reasons, like: productivity enhancement, sub-aquatic tourism, fish trawling reduction, etc. However little information was known about the impacts of artificial reef, such positives than negatives, in the first semester of 2004 a law project, in Brazil, was approved liberating the practice by many ecological reasons. The present study was developed in Porto Belo Island, in the shore of Santa Catarina, Brazil. Six unities of ReefBall TM, in two blocks of three unities, were placed near the island. One block was placed near the island rocky shore (RD) and the other block 60 meters far from the rocky shore (RF). Fish visual censuses were done by SCUBA, monthly, since October of 2002 to September of 2003 in both sites. The pattern of species succession in each block was characterized by cumulated curves of species in the time long, and the curves calibrated by the minimum squares and the angular coefficient founded for each one of the sites compared by the Student Test. A Total of 23 species was identified for RD and 8 to RF. The increasing number of species, measured by the angular coefficient of each equation, was significant different (t cal(b1- b2) =4,474; p<<0,01) and superior in the block near the rocky shore (bRD=1,503; bRF=0,682). Different raising pattern in the species number could be verified when compare the both succession curves, RF showed two distinct pulses. In RD the raising number of species also was verified however this raise was more gradual and continual. The results indicated that the proximity to other natural subtract act directly on the colonization process by fishes in artificial structures.