VARIAÇÕES ESPACIAIS E TEMPORAIS NO DESENVOLVIMENTO VEGETATIVO E REPRODUTIVO DA MACROALGA Sargassum C. Agardh (Fucales, Phaeophyceae) -- SÍNTESE DO CONHECIMENTO

The Sargassum C. Agardh (Fucales, Phaeophyceae) genus is composed by species of recognized ecological importance to coastal ecosystems, especially to rocky shore communities of tropical and warm temperate zones. Some species are considered valuable for presenting substances of potential biotechnological uses. However, the biological parameters of growth and reproduction of the species are insufficiently known, like the determinant factors causing variations within and among the different populations. The present study summarizes what is known about temporal and spatial variations in the vegetative and reproductive development of Sargassum species, based on the scientific literature.Sargassum C. Agardh (Fucales, Phaeophyceae) é um gênero de reconhecida importância ecológica nos ecossistemas costeiros, particularmente nas comunidades de costões rochosos de regiões tropicais e temperadas quentes. Algumas espécies são consideradas ainda de importância econômica, por produzirem compostos químicos com potencial aplicação biotecnológica. No entanto, aspectos biológicos vinculados ao crescimento e reprodução dessa macroalga não são bem conhecidos, assim como os fatores determinantes das  variações intra e inter-populacionais destes aspectos. Este trabalho sintetiza o conhecimento sobre as variações espaciais e temporais no desenvolvimento vegetativo e reprodutivo de espécies de Sargassum, com base na literatura.

Abundance of the reef-building Petaloconchus varians (Gastropoda: Vermetidae) on intertidal rocky shores at Ilha Grande Bay, southeastern Brazil

ABSTRACT The reef-building vermetid Petaloconchus varians occurs in the western Atlantic Ocean, from the Caribbean Sea to the southern coast of Brazil. The present study evaluated the abundance of P. varians on intertidal rocky shores in Ilha Grande Bay (Rio de Janeiro State), and characterized their reefs, describing the species density, besides the weight and the belt width of the reefs. Petaloconchus varians reefs were recorded at 25 sites, with rocky shores exposed to different wave action (very sheltered, sheltered, semi-exposed and exposed) and slopes (10° to 46°). Clusters of individuals constructed large reefs along the middle intertidal zone, creating a wide belt (38 cm to 2 m). The density of P. varians and the weight of the reefs ranged from 620 to 2,559 ind.100 cm-2 and from 100 to 1,500 g.100 cm-2, respectively. Considering that the species was last reported from the area in the mid-20th century, the present study suggests that P. varians reefs are becoming dominant in the intertidal zone of rocky shores in Ilha Grande Bay. This is a contribution to knowledge of this ecosystem in Ilha Grande Bay, in view of local or global ecological changes