HR: 1330h
AN: NB33C-17    [Abstracts]
TI: Effects of Submerged Aquatic Vegetation on Macrobenthos in a Coastal Lagoon of the Southwestern Atlantic
AU: * Arocena, R
EM: rarocena@fcien.edu.uy
AF: Rafael Arocena, Secci¢n Limnologia, Facultad de Ciencias, Universidad de la Republica, Montevideo, 11400 Uruguay
AB: The northern, freshwater-dominated, edge of Rocha coastal lagoon in Uruguay, South America, was invaded during recent years by submerged aquatic vegetation (SAV). To evaluate the effect of SAV on the composition and abundance of macrozoobenthos, I compared this assemblage between a site that was vegetated in summer-autumn (V) to another one that was always bare (N). Only station V often showed thermal stratification, due to a reduction in water circulation caused by the plants (Potamogeton, Cabomba, Myriophyillum, Ruppia). Both sites had similar water quality and sediment characteristics (70 % sand, 30 % silt). I found a total of 28 benthic taxa: 3 species of Polychaeta, 2 of Mollusca, 3 of Crustacea and 20 genera of Insecta. Taxon richness and total abundance of invertebrates, as well as individual abundance of amphipods, gastropods and chironomids were significantly higher at V compared with N. Conversely, the crustacean Tanais stanfordi, the clam Erodona mactroides and the polychaete Laeonereis culveri were significantly more abundant at the unvegetated site. Moreover, Shannon diversity was higher at N than at V. These results show that the colonization by plants may enhance the variety and the abundance of benthos.
DE: 1845 Limnology
DE: 1890 Wetlands
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly