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Seagrass Biomass (seagrass + biomass)
Selected AbstractsSeagrass,sea urchin interaction in shallow littoral zones of Dar es Salaam, TanzaniaAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue S1 2009Florence Mamboya Abstract 1.Seagrasses biomass, canopy height, shoot density, percentage cover, and sea urchin abundance were intermittently (between July and November 2007) studied at four littoral sites in the Dar es Salaam area (Mjimwema, Mbweni, Bongoyo Island and Mbudya Island) in order to investigate the seagrass,sea urchin association. 2.Seagrass biomass ranged from 126.7±65.62,g,dwt,m,2 in the upper sub-tidal area at Bongoyo Island to 508.1±133.4,g,dwt,m,2 in the upper sub-littoral area at Mbudya Island. Canopy height ranged from 6.51±2.76,cm in the mid-littoral zone at Mjimwema to 23.8±8.93,cm in the upper sub-littoral zone at Mbudya Island. Shoot densities ranged from 363.6±268.9 shoots m,2 in the mid-littoral zone at Mjimwema to 744.0±466.9 shoots,m,2 in the lower littoral zone at Mbudya Island. 3.Seagrass biomass, canopy height and percentage cover differed significantly among study sites (P=0.001, 0.0001, 0.008 respectively). However, there was no significant difference in shoot density among the sites (P=0.376). 4.Ten species of sea urchins were recorded, Echinometra mathaei being the most abundant followed by Tripneustes gratilla. Total sea urchin abundance was significantly different among the study sites (P=0.001). Seagrass,sea urchin interaction was depicted by significant negative correlations between sea urchin densities with seagrass biomass, canopy height, shoot density and percentage cover. This suggests that grazing by sea urchins might have contributed to the reduction of above ground seagrass biomass in locations with higher sea urchin densities. However, further studies are required to corroborate the present results and assess effects of other factors (e.g. light, nutrients and currents), which also influence seagrass growth. Copyright © 2009 John Wiley & Sons, Ltd. [source] Response of fauna in seagrass to habitat edges, patch attributes and hydrodynamicsAUSTRAL ECOLOGY, Issue 5 2010HANNAH M. MURPHY Abstract This study has investigated the taxon-specific responses of fauna to patch edges, and how these relate to patch attributes (patch size, seagrass biomass and water depth), and hydrodynamics in the seagrass habitat. Faunal abundances were sampled at the edge, 2 m in from the edge, and in the middle of 10 seagrass patches of variable size in Port Phillip Bay, Australia. Five of nine taxa showed edge effects. There were higher abundances at the edge compared with the middle for porcellid harpacticoids, and an increase in abundance from the edge to the middle of the patches for tanaids and isopods. For caprellid and gammarid amphipods, the edge effect varied across patches. Changes in current within the patch and patch size were related to the variability in the edge effect pattern of caprellids. None of the measured environmental variables (seagrass biomass, current and water depth) or patch size had a role in the variable edge effect pattern of gammarid amphipods. At the patch level, the distribution of six of nine taxa in this study, namely isopods, polychaetes, ,other harpacticoids', porcellid harpacticoids, cumaceans and gammarid amphipods, was related to differences in average water depth, average seagrass biomass and patch size. Our study indicates that the faunal response to edges cannot be generalized across seagrass habitat, and the implications of habitat area loss will vary depending on the taxon under consideration. [source] | ||||||||||