Coral Siderastrea Research Articles

Late Miocene and Early Pliocene coastal deposits from the Canary Islands: New records and paleoclimatic significance

The Canary Islands offer an outstanding context for paleoclimatic studies because their volcanic nature and the presence of datable lava flows, their antiquity, the existence of marine deposits and their location in the NE Atlantic. New records of Miocene and Pliocene coastal deposits are registered in the eastern Canary Islands, 100 km off the NW African coast.Late Miocene marine deposits are conglomerates and sandstones assigned to the Tortonian through a new 40Ar/39Ar age (9.60 ± 0.05 Ma) of an overlying lava flow at the Janubio site in Lanzarote Island. These deposits contain littoral-intertidal and intertropical genera of fossils, e.g. the gastropod Nerita and the coral Siderastrea, they are almost horizontal and were elevated up to 36 m in height by regional or local tectonics, yielding a relatively low rate of uplift of ~3.75 m/Ma.Furthermore, Early Pliocene coastal deposits studied, are mainly marine conglomerates and sandstones and derived aeolianites that are spread over the south of Lanzarote and the west of the Jandía peninsula of Fuerteventura Island. No associated lava flow permits their dating, but they contain marine fossils of littoral and intertropical genera, as the gastropods Nerita and Persististrombus and the coral Siderastrea. They are all inclined toward the coast in the form of a large layer elevated up to 70 m a.s.l., in a surrounding geological environment with gypsum and aeolianites that indicate a eustatic sea-level fall with a regressive effect in the area. These deposits, previously attributed to the Quaternary, are now assigned to the Zanclean because of its similarity in lithology, appearance and fossil content with deposits in western Fuerteventura and NE Gran Canaria.The nearby existence of paleosols with particular structures indicates the start of climatic seasonality in the region; and the only possible time interval in a global context (record of deep-sea oxygen isotopes and sea-level history) fits in the most notable Pliocene global climatic change (~4 Ma) that is registered in the Canary Islands by mean of these coastal and aeolian deposits.

Reef Bioconstructors of Rocas Atoll, Equatorial South Atlantic doi: 10.5007/2175-7925.2011v24n2p37

This study presents a analysis of reef bioconstructors at Rocas Atoll, Northeast of Brazil, sampled in January and February of 2008. The results show the presence of a community made up mainly of calcareous algae (Porolython pachydermum, Sporolython sp., Lythoporella sp., Lythophyllum sp.), corals (Siderastrea stellata, Favia gravida), vermetids (Dendropoma irregular, Petaloconchus varians) and foraminifers (Homotrema rubrum) in the reef formation. This taxonomic survey show the importance of a different species during the carbonate growth process of the only Atoll of the Equatorial South Atlantic.

Proximal Sensing of Coral Features: Spectral Characterization of Siderastrea siderea

Remote sensing has been suggested as a potential tool for monitoring coral-reef ecosystems. However, before remote sensing can be viewed as a practical monitoring and diagnostic tool for entire coral communities, there is a need to understand the spectral responses from individual coral species. Toward that end, it seems important to not only establish the range of natural variability in spectral reflectance but also to develop procedures to enhance understanding of the spectra. This paper describes our data collection approach as well as a procedure for examining the spectral features associated with one species of coral (Siderastrea siderea). The paper also examines the spectral variability in reflectance within samples of the same species and suggests a procedure for highlighting the spectral positions of absorbers/pigments, thus yielding useful information about pigment composition in one coral species.