The meiofauna asssociated whith Sargassum cymosum at Lázaro Beach, Ubatuba, São Paulo

Abstract

In this study, the meiofauna associated with Sargassum cymosum was qualitatively and quantitatively analyzed between December 1990 and July 1991. Sampling was carried out on a moderately exposed shore at Lázaro Beach, Ubatuba (32°S - 45°W). Each alga was washed in a formaldehyde solution and the fauna in suspension was washed through a series of 500, 250, 120 and 60 µm mesh sieves. The biomass of each taxonomic group was estimated as ash-free dry weight (AFDW) according to size categories. Algae volume and dry weight were determined, incIuding epiphytes. Densities of epifauna ranged from 502.9 to 2706.6 ind.20 ml-1 as algae volume. The biomass values (326.6 to 1214.4 µg.20 ml-1 AFDW) represented a low standing stock. Harpacticoid copepods and their nauplii were the dominant group and also showed the highest biomass values, being represented by larger individuaIs (250 to 120 µm). Higher values were observed between the end of the summer and the beginning of the fali (March and April), decreasing until winter (July). This variation may be explained by habitat complexity changes, or reproduction of some taxa, as higher meiofaunal densities were found on the 60 µm mesh sieve, incIuding high percentages of nauplii.

Association of Epialtus brasiliensis Dana, 1852 (Brachyura, Majoidea) with different species of seaweed

“…Sargassum cymosum are more complex than H. musciformis, followed by A. spicifera (Leite et al, 2007;Costa et al, 2012;Nassar, 2012), so it is expected that more complex environments, such as S. cymosum, would exhibit a higher abundance of spider crabs (Gartner et al, 2013). Usually, larger seaweed volumes are associated with greater complexity and consequently, a higher number of organisms (Hacker and Steneck, 1990;Curvelo and Corbisier, 2000;Gartner et al, 2013). This pattern was not, however, supported in the present study, since the density of E. brasiliensis was the same in S. cymosum and H. musciformis, the former of which had an intermediary volume among the analyzed seaweed species.…”

Two new species of Diarthrodes (Copepoda: Harpacticoida: Dactylopusiidae) from the Caribbean coast of Colombia

“…Several species are known to live as epior endophytic forms in association with algae (Shimono et al, 2007); they display a unique feeding strategy, by segregating a mucus-trap to agglutinate bacteria. The 2 described species of Diarthrodes were found in the plankton net but it is likely that more species of this genus could be recovered by sampling the invertebrate community dwelling among algal patches (Alper et al, 2010;Curvelo & Corbisier, 2000). Further research on the biology, life cycle and feeding of the Colombian species, and their possible association with algae, are clearly interesting research subjects regarding this genus in the surveyed area.…”

State of the art of the meiofauna of Brazilian Sandy Beaches

“…The role of biological interactions on sandy beaches are less studied since it is commonly accepted that this structural factor is of less importance in dynamic environments (DEFEO; MCLACHLAN, 2005); as a result there are only two studies related to this issue as related to southeastern sandy beaches (see CURVELO;CORBISIER, 2000;MARIA et al, 2013b). In the former one, the variation of meiofauna density between the seasons is related to the habitat heterogeneity resulting from the presence of the algae Sargassum cymosum on the rocky shore whereas in the latter study the presence of polychaetes -Scolelepis -seems not to influence the nematode community.…”