Filamentous algae dominate a tropical reef community in the Mexican Caribbean: an unexpected organisation of reef vegetation

Abstract

The algal community of a small marine lagoon in the tropical Mexican Caribbean Sea was studied for 3 years (1994-1997). Filamentous algae dominated the vegetation and calcareous crusts were the principal understory algae, The filamentous algae formed dense mats, their cover showing seasonal variation, ranging between 30% in late winter and early spring, and 80% in summer and autumn. Hurricane Roxane (October 1995) caused increased sedimentation, accompanied by a considerable reduction in cover of the filamentous algae. Cover reached pre-hurricane levels within approximate to 11 months. Herbivorous fishes (mainly scarids) maintained specific feeding areas, which they cleared of filamentous algae, however, they did not control the filamentous algae throughout the lagoon. Water movement was almost completely absent in the lagoon of Chankanaab Park, which together with the low herbivore pressure, were most likely responsible for the unique environment, where a vegetation dominated by thick filamentous mats formed the climax community.