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Coralreef fish desperately needs mangrove forests and seagrass fields

Netherlands Organization for Scientific Research

Biologists from the University of Nijmegen have demonstrated that some coral fish really do choose nursery grounds before heading for the coral reef. According to the researchers, managers of the waters around the Caribbean islands must devote more attention to the coast as a whole and not just to the protection of coral reefs.

Up until now scientists suspected that seagrass fields and mangrove forests (trees which can survive in salt water) were nursery grounds for coral fish because young fish were often found there. However, there was a lack of scientific evidence to support this. The conclusions from the Nijmegen research have changed this. They lend support to the idea that mangrove forests and seagrass fields are an indispensable and stable nursery ground for coral reef fish around the Caribbean islands of Curaçao, Bonaire, Saba and Belize.

The Nijmegen PhD student Elroy Cocheret de la Morinière studied the nine most common fish species in the nursery grounds around Curaçao. He examined how each of these nine species behaved around mangrove and seagrass fields as well as on coral reefs.

It turned out that the nine species of fish did not enter the nursery grounds by chance before subsequently moving to a coral reef. The coral fish deliberately chose a certain place. An examination of the fishes' stomach contents together with chemical analyses revealed that the fish use the mangrove forests as a shelter from predatory fish. The seagrass fields not only serve as a safe haven but also as a feeding place.

Due to changes in their diet, carnivorous species move from the nursery ground to the coral reef whilst still immature. The herbivorous fish mostly depart due to becoming mature.

The coral fish are important for both commercial fishing and local subsistence fishers in the tropics. Until now mangroves have often been chopped down, to build jetties for example. The seagrass fields are frequently polluted. The researchers state that the mangroves and seagrass fields must be protected. Without the nursery grounds, a number of very common and economically important coral fish species will not survive.


Further information can be obtained from Elroy Cocheret de la Morinière (Department of Aquatic Ecology & Environmental Biology, University of Nijmegen), tel.+31 (0)24 3653182, fax +31 (0)24 3652134, e-mail, internet (note the capital letters) or assistant supervisor Prof. Gerard van der Velde, tel.+31 (0)24 3652621. The defence of the dotoral thesis will take place on 19 November 2002. Mr Cocheret de la Morinière's supervisor is Prof. Piet Nienhuis.

The research was funded by the Netherlands Organisation for Scientific Research (NWO).

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