The abundance of reef builders, non-builders and the calcium carbonate produced by communities established in Calcification Accretion Units (CAUs) were determined in three Abrolhos Bank shallow reefs during the period from 2012 to 2014. In addition, the seawater temperature, the irradiance, and the amount and composition of the sediments were determined. The inner and outer reef arcs were compared. CAUs located on the inner reef shelf were under the influence of terrigenous sediments. On the outer reefs, the sediments were composed primarily of marine biogenic carbonates. The mean carbonate production in shallow reefs of Abrolhos was 579 ± 98 g m-2 y-1. The builder community was dominated by crustose coralline algae, while the non-builder community was dominated by turf. A marine heat wave was detected during the summer of 2013–2014, and the number of consecutive days with a temperature above or below the summer mean was positively correlated with the turf cover increase. The mean carbonate production of the shallow reefs of Abrolhos Bank was greater than the estimated carbonate production measured for artificial structures on several other shallow reefs of the world. The calcimass was higher than the non-calcareous mass, suggesting that the Abrolhos reefs are still in a positive carbonate production balance. Given that marine heat waves produce an increase of turf cover on the shallow reefs of the Abrolhos, a decrease in the cover represented by reef builders and shifting carbonate production are expected in the near future.
ABSTRACT(Benthic marine algae from Cabo Frio region and surroundings: synthesis of knowledge) At the last decades, several studies were done about benthic marine algae from Cabo Frio region (RCF), meanwhile the obtained information is scattered in specific publication, monographs and thesis. In this context, the aim of this work is to revise the literature about marine algae from RCF, providing a detailed list of taxa, and analyzing the floristic composition and geographical distribution of benthic marine algae of this importance region from the Brazilian coast. It was found 339 infrageneric taxa, distributed in 76 Chlorophyta, 60 Ochrophyta and 203 Rhodophyta. The municipalities with higher number of taxa were Armação dos Búzios (212) and Arraial do Cabo (207). It was found that 20 of the 339 taxa listed presented distribution restricted to RCF when comparing with the taxa registered to the Brazilian coast and that 8 taxa presented affinities with temperate waters. The species Pseudolithoderma moreirae Yoneshigue & Boudouresque and Gracilaria yoneshigueana Gurgel, Fredericq & J. Norris are endemic to RCF. From the obtained data that indicates an elevate species richness and the presence of number species with restricted and discontinued distribution we can affirm that RCF is one of the most important diversity center of marine algae in Brazil.
Crustose Coralline Algae (CCA) are important constituents of tropical coral reef environments throughout the world's oceans, acting as structural reinforcement and recruitment cues. Despite their importance and their ubiquity, very little is known of the biodiversity of CCA in remote areas of the world's oceans. On the Saint Peter and Saint Paul Archipelago (SPSPA), located in the central equatorial Atlantic Ocean, CCA occur abundantly in intertidal rock pools and the surrounding subtidal zones. This study represents the first attempt at detailing the CCA species composition for the archipelago along a depth interval between 0 to 70 m. Seven taxa of CCA were identified: Corallinaceae sp., Hydrolithon rupestre, Hydrolithon sp., Lithophyllum johansenii, Lithothamnion muelleri, Mesophyllum engelhartii, and Titanoderma pustulatum pustulatum. A decrease in CCA species richness and change in species composition was seen from shallow to deeper zones that can be explained by a significant reduction in temperature and photon irradiance observed bellow 30 m depth.
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