Three years of benthic communities on an artificial reef in Canary Islands

Abstract

An artificial reef was constructed in the southern coast of Gran Canaria Island (Canary Islands, Spain), with the aim to increase coastal fisheries. The artificial reef complex is compossed of 84 modular concrete blocks or live different designs, which are distributed in five separated groups. The biological assessment was carried during the last three years between November 1991 and December 1994. A comparative study of associated communities was done with Scuba diving methods. Samples of benthic invertebrates, macroalgae and fishes were obtained in the artificial reef and in a close natural reef.\nThis study define several stages in the succesion and dynamics of benthic communities, as well as the use of the different species in each type of module. Four main succesional stages were determined Initial colonization. Structuring stage. Bloom of sea urchin population and Stabilization stage. Although fisheries activities were prohibited during the first 3 year after deployment, the use of non-selective fisheries technics in the area interrupted the natural dynamic, modifing the community structure. During the last 13 months, a long spined sea urchin proliferation has occupied the modules, eliminating the vegetal and animal cover, changing food and refuge availability, biodiversity, etc.