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Rio de Janeiro, Brazil

Scherner F.,University of Pernambuco | Pereira C.M.,Instituto Coral Vivo | Duarte G.,Instituto Coral Vivo | Duarte G.,Federal University of Rio de Janeiro | And 7 more authors.
PLoS ONE | Year: 2016

Climate change is a global phenomenon that is considered an important threat to marine ecosystems. Ocean acidification and increased seawater temperatures are among the consequences of this phenomenon. The comprehension of the effects of these alterations on marine organisms, in particular on calcified macroalgae, is still modest despite its great importance. There are evidences that macroalgae inhabiting highly variable environments are relatively resilient to such changes. Thus, the aim of this study was to evaluate experimentally the effects of CO2-driven ocean acidification and temperature rises on the photosynthesis of calcified macroalgae inhabiting the intertidal region, a highly variable environment. The experiments were performed in a reef mesocosm in a tropical region on the Brazilian coast, using three species of frondose calcifying macroalgae (Halimeda cuneata, Padina gymnospora, and Tricleocarpa cylindrica) and crustose coralline algae. The acidification experiment consisted of three treatments with pH levels below those occurring in the region (-0.3, -0.6, -0.9). For the temperature experiment, three temperature levels above those occurring naturally in the region (+1, +2, +4°C) were determined. The results of the acidification experiment indicate an increase on the optimum quantum yield by T. cylindrica and a decline of this parameter by coralline algae, although both only occurred at the extreme acidification treatment (-0.9). The energy dissipation mechanisms of these algae were also altered at this extreme condition. Significant effects of the temperature experiment were limited to an enhancement of the photosynthetic performance by H. cuneata although only at a modest temperature increase (+1°C). In general, the results indicate a possible photosynthetic adaptation and/or acclimation of the studied macroalgae to the expected future ocean acidification and temperature rises, as separate factors. Such relative resilience may be a result of the highly variable environment they inhabit. © 2016 Scherner et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Liedke A.M.R.,Federal University of Parana | Liedke A.M.R.,Federal University of Santa Catarina | Barneche D.R.,Monash University | Ferreira C.E.L.,Federal University of Fluminense | And 10 more authors.
Marine Biology | Year: 2016

The feeding behaviour and diet plasticity of a given species are usually shaped by the relationship between species physiology and the quality and availability of resources in the environment. As such, some species may achieve wide geographical distributions by utilizing multiple resources at different sites within their ranges. We studied the distribution and feeding of Chaetodon striatus, the most widespread butterflyfish in the Atlantic, by assessing its density and foraging rates in eight sites enclosing 44° of latitude. We also evaluated the relationship between fish density and foraging rates with nutritional condition and diet across study sites, and the gut length relative to body size. Density and foraging rates did not differ among studied sites. In 169 stomachs analysed, we found 52 different items (12–23 per site). Polychaeta and Cnidaria were the most important items in seven study sites. Therefore, C. striatus may be considered as a non-coral generalist feeder, as it feeds on a wide variety of items and substrata along the studied range, with no consistent selectivity pattern for foraging substratum across sites. Individuals from all sites but Salvador (NE Brazil) had similar RNA/DNA ratios, suggesting that C. striatus nutritional condition is similar along its extensive distribution. Our findings highlight the importance of assessing different sites within the distribution range of generalist butterflyfishes, and different variables, to a better comprehension of the feeding ecology of these species. © 2016, Springer-Verlag Berlin Heidelberg. Source

Longo G.O.,Federal University of Santa Catarina | Morais R.A.,Federal University of Santa Catarina | Martins C.D.L.,Federal University of Santa Catarina | Mendes T.C.,Federal University of Fluminense | And 17 more authors.
PLoS ONE | Year: 2015

The Southwestern Atlantic harbors unique and relatively understudied reef systems, including the only atoll in South Atlantic: Rocas atoll. Located 230 km off the NE Brazilian coast, Rocas is formed by coralline red algae and vermetid mollusks, and is potentially one of the most "pristine" areas in Southwestern Atlantic. We provide the first comprehensive and integrative description of the fish and benthic communities inhabiting different shallow reef habitats of Rocas. We studied two contrasting tide pool habitats: open pools, which communicate with the open ocean even during low tides, thus more exposed to wave action; and closed pools, which remain isolated during low tide and are comparatively less exposed. Reef fish assemblages, benthic cover, algal turfs and fish feeding pressure on the benthos remarkably varied between open and closed pools. The planktivore Thalassoma noronhanum was the most abundant fish species in both habitats. In terms of biomass, the lemon shark Negaprion brevirostris and the omnivore Melichtys niger were dominant in open pools, while herbivorous fishes (mainly Acanthurus spp.) prevailed in closed pools. Overall benthic cover was dominated by algal turfs, composed of articulated calcareous algae in open pools and non-calcified algae in closed pools. Feeding pressure was dominated by acanthurids and was 10-fold lower in open pools than in closed pools. Besides different wave exposure conditions, such pattern could also be related to the presence of sharks in open pools, prompting herbivorous fish to feed more in closed pools. This might indirectly affect the structure of reef fish assemblages and benthic communities. The macroalgae Digenea simplex, which is uncommon in closed pools and abundant in the reef flat, was highly preferred in herbivory assays, indicating that herbivory by fishes might be shaping this distribution pattern. The variations in benthic and reef fish communities, and feeding pressure on the benthos between open and closed pools suggest that the dynamics in open pools is mostly driven by physical factors and the tolerance of organisms to harsh conditions, while in closed pools direct and indirect effects of species interactions also play an important role. Understanding the mechanisms shaping biological communities and how they scale-up to ecosystem functioning is particularly important on isolated near-pristine systems where natural processes can still be studied under limited human impact. © 2015 Longo et al. This is an open access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Source

Santos H.F.,Federal University of Rio de Janeiro | Santos H.F.,Instituto Coral Vivo | Carmo F.L.,Federal University of Rio de Janeiro | Martirez N.,Federal University of Rio de Janeiro | And 12 more authors.
Diseases of Aquatic Organisms | Year: 2016

Coral reefs are at risk due to events associated with human activities, which have resulted in the increasing occurrence of coral diseases. Corals live in symbiotic relationships with different microorganisms, such as cyanobacteria, a very important group. Members of the phylum Cyanobacteria are found in great abundance in the marine environment and may play an essential role in keeping corals healthy but may also be pathogenic. Furthermore, some studies are showing a rise in cyanobacterial abundance in coral reefs as a result of climate change. The current study aimed to improve our understanding of the relationship between cyanobacteria and coral health. Our results revealed that the cyanobacterial genus GPI (Anabaena) is a possible opportunistic pathogen of the coral species Millepora alcicornis in the South Atlantic Ocean. Furthermore, the bacterial and microeukaryotic profile of healthy, diseased, and post-disease (skeletal) regions of affected coral indicated that a microbial consortium composed of Anabaena sp., Prosthecochloris sp., and microeukaryotes could be involved in this pathogenicity or could be taking advantage of the diseased state. © Inter-Research 2016. Source

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