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- Title
Coralline Algae Depositional Environments on the Brazilian Central-South-Eastern Shelf.
- Authors
de Macedo Dias, Gilberto Tavares; Villaça, Roberto Campos
- Abstract
DIAS, G.T.M., and VILLAÇA, R.C., 2012. Coralline algae depositional environments on the Brazilian central-south-eastern shelf. The Brazilian central shelf along the State of Espirito Santo features several palaeochannels eroded into deposits of coralline algae. Seismic profiles and jet-probe cores have shown a layer of calcareous sediments over 10 m thick that is formed mainly by the fragmentation of coralline algae. Video and scuba-diving observations demonstrate that dense aggregations of rhodoliths often change position on the sea bottom as a result of being dragged ('sail' effect) by foliose algae such as Sargassum, Dictyopteris, and Zonaria. The benthic fauna associated with rhodoliths or foliose macroalgae ( Hydrozoa and Amphipoda) is dominated by polychaetes, ophiuroids, and molluscs. The sessile fauna is poorly represented, consisting of some sponge species. It was possible to verify the following dynamics: (i) in summer, foliose macroalgae and zoobenthos (phytal) are established upon the rhodoliths; (ii) in early and midwinter, epiphytic macroalgae are senescent; (iii) in late winter, storms disturb sediments on the sea bottom, burying living rhodoliths and removing the foliose algae; and (iv) in spring, a bloom of the bivalvia Pinctata pectinata occurs, overgrowing the bottom. The rhodoliths tend to remain on the seafloor (with 10%% to 20%% estimated buried and becoming permanently incorporated to the sediment mass). The sediment dynamics are strongly dominated by erosive phases related to storms.
- Subjects
BRAZIL; CORALLINE algae; RED algae; BENTHIC animals; POLYCHAETA; OPHIUROIDEA; MOLLUSKS; PALEOGEOGRAPHY
- Publication
Journal of Coastal Research, 2012, Vol 28, Issue 1, p270
- ISSN
0749-0208
- Publication type
Article
- DOI
10.2112/11T-00003.1