Seria a macrofauna bentônica de fundos não consolidados influenciada pelo aumento na complexidade estrutural do habitat? o caso do estuário da Lagoa dos Patos

Abstract

Rosa, L.C. & Bemvenuti, C.E. 2007. Would be the benthic macrofauna of the soft-bottoms influenced by increase in the habitat structural complexity? The Patos Lagoon estuary as a case study. Braz. J. Aquat. Sci. Technol. 11(1):51-56. ISSN 1808-7035. The main objective of this study was to evaluate the influence of vegetated beds on macrofauna community structure of the estuarine soft bottoms of the Patos Lagoon, southern Brazil. Comparative analyses were made by faunal samples collected inside and outside in two kinds of vegetated beds: a sea grass meadows during the summer period and, an algal mats at winter one. The presence of theses vegetated beds had essentially favoring highest densities of epifaunal organisms by increase of substratum for fixation and feeding, which could to result at decrease of evenness and, consequently, of the diversity of macrofauna inside these beds such as registered at summer survey. Differences in the both evenness and diversity at winter survey as well in the composition and number of species at both times were not observed among habitats. These results indicate that the increase at structural complexity of habitat promoted by presence of vegetated beds not necessarily favoring the increase of the macrofauna diversity of the estuarine region of the Patos Lagoon.

Influence of the shoot density of Halodule wrightii Ascherson from rocky and sandy habitats on associated macroalgal communities

“…While epiphyte blooms in seagrass meadows may have important economic and ecological consequences (CHO et al, 2003), the main relationships described in the literature for epiphytes and seagrass meadows are competition for oxygen (SAND-JENSEN;REVSBACH;JORGENSEN, 1985) and shading of the seagrasses by the algae (SAND-JENSEN, 1977;SILBERSTEIN et al, 1986;BRUN et al, 2003). However, as the biomass of the epiphytes sampled here was low, they do not seem to be present in sufficient amounts to cause damage to the meadows, a situation also observed by other authors (BOROWITZKA et al, 1990;ASMUS, 2001).…”

“…In fact, the algae and seagrasses may be benefiting each other in some respects. Positive effects of algae on seagrasses may include a reduction in both the hydrodynamic and desiccation effects during periods of exposure to air (HARLIN, 1975;PENHALE;SMITH, 1977;SAND-JENSEN;REVSBACH;JORGENSEN, 1985;SILBERSTEIN et al, 1986;BOROWITZKA et al, 1990). Furthermore, the decomposition products of algae may also be excellent sources of nutrients for seagrasses (MAZZELLA;ALBERTE, 1986).…”

“…Under conditions of low algae biomass, it is probable that these systems are only exchanging nutrients, without damage to either system. Seagrasses and rhizophytic algae may have a symbiotic relationship (WILLIAMS, 1990;CINELLI, 1997CINELLI, , 1998CINELLI, , 1999PAULA et al, 2003;PERGENT et al, 2008) or may compete for nutrients (SAND-JENSEN, 1977;CINELLI, 1997;DAVIS;FOURQUEAN, 2001) and space (TAPLIN et al, 2005;STAFFORD;BELL, 2006). However, this relationship seems to be determined by the algal biomass and the total seagrass-host biomass ratio (BOROWITZKA et al, 1990;ASMUS, 2001).…”

“…Both positive and negative effects of seagrass-algae relationships are reported in the literature (SAND-JENSEN, 1977;SILBERSTEIN et al, 1986;WILLIAMS, 1990;CINELLI, 1997CINELLI, , 1998CINELLI, , 1999ASMUS, 2001;BRUN et al, 2003;TAPLIN et al, 2005;STAFFORD;BELL, 2006;PERGENT et al, 2008). In general, the combination of macroalgae and seagrasses may, to some extent, increase the area available for colonization, increasing food retention and shelter for fauna, and enhancing the productivity of the coastal environment (MAZZELLA; ALBERTE, 1985;ZIEMAN;ZIEMAN, 1989;VIRNSTEIN;CARBONARA, 1985;NORKKO et al, 2000;WILLIAMS;HECK, 2001;BOROWITZKA et al, 2006;ROSA;BEMVENUTI, 2007).…”

Responses of the molluscan fauna to environmental variations in a Halodule wrightii Ascherson ecosystem from Northeastern Brazil

“…Corbisier 1994, Garcia et al 1996, Garcia and Vieira 1997, da Rocha et al 2006. However, several studies have indicated that even little seagrasses may provide greater density and diversity of macrofauna than non-vegetated Lee et al 2001, Casares and Creed 2008, Rosa and Bemvenuti 2007. Despite the environmental influences recorded, this studied seagrass meadow had a significant role on the spatial and temporal distributions of the molluscan fauna.…”