Rhodoliths in Brazil: Current knowledge and potential impacts of climate change

Abstract

Financial Support: CNPQ, CAPES, FAPESP.Rhodolith beds are important marine benthic ecosystems, representing oases of high biodiversity among sedimentary seabed environments. They are found frequently and abundantly, acting as major carbonate 'factories' and playing a key role in the biogeochemical cycling of carbonates in the South Atlantic. Rhodoliths are under threat due to global change (mainly related to ocean acidification and global warming) and local stressors, such as fishing and coastal run-off. Here, we review different aspects of the biology of these organisms, highlighting the predicted effects of global change, considering the additional impact of local stressors. Ocean acidification (OA) represents a particular threat that can reduce calcification or even promote the decalcification of these bioengineers, thus increasing the ecophysiological imbalance between calcareous and fleshy algae. OA should be considered, but this together with extreme events such as heat waves and storms, as main stressors of these ecosystems at the present time, will worsen in the future, especially if possible interactions with local stressors like coastal pollution are taken into consideration. Thus, in Brazil there is a serious need for starting monitoring programs and promote innovative experimental infrastructure in order to improve our knowledge of these rich environments, optimize management efforts and enhance the needed conservation initiatives. AbstrActDescriptors: Algae, Conservation, Brazil, Global warming, Pollution, Ocean acidification.Bancos de rodolitos formam oásis de alta biodiversidade em ambientes marinhos de fundo arenoso. Os rodolitos são formados por espécies bioconstrutoras, que fornecem abrigo e substrato para diversas e abundantes comunidades bentônicas. No Brasil esses ambientes são frequentes, representando grandes "fábricas" de carbonato com um papel fundamental no ciclo biogeoquímico do carbono no Atlântico Sul. Estes organismos e ambientes estão ameaçados pelas mudanças climáticas (principalmente a acidificação dos oceanos e o aquecimento global) e pelos estressores locais, tais como os impactos causados pela pesca e as descargas costeiras de efluentes. Neste trabalho fazemos uma revisão da taxonomia, filogenia e biologia desses organismos, com destaque para os efeitos previstos das mudanças climáticas e suas relações com estressores locais. A maioria dos estudos acerca dos efeitos das mudanças climáticas e da acidificação dos oceanos em algas calcárias relatam respostas negativas não só no crescimento e na calcificação, mas também no processo de fotossíntese, espessura da parede celular, reprodução e sobrevivência das algas. Este cenário reforça a necessidade em estabelecer uma consistente rede de trabalho para proporcionar um programa de monitoramento amplo e de longo prazo, bem como infraestrutura para avaliações experimentais de impactos locais e regionais das mudanças climáticas e dos estressores locais em bancos de rodolitos.

Echinodermata associated to rhodoliths from Seixas Beach, State of Paraíba, Northeast Brazil

“…In Brazil, rhodolith beds are among the largest deposits of CaCO 3 in the world (Amado-Filho et al 2012). These rhodoliths provide refuge, food and other resources, protecting organisms from competitive exclusion, predation, and physical disturbance (Riul et al 2009, Horta et al 2016. The Seixas Beach has a large bank of rhodoliths susceptible to degradation by anthropogenic impact, in the form of tourism and commercial exploitation.…”

Climate Change Feeds Climate Changes

“…number of stomata per mm 2 of leaf area. 12 where eventual impact will change regional and eventually global dynamic of DMS availability. Experiments showed in the artic that elevated CO 2 conditions somehow reduce the DMS concentrations even in planktonic environment, despite modelling studies suggest increases in DMS emission of 30to >150%.…”

“…current coal and gas thermoelectric power plants) or the world most likely will anticipate extreme and dramatic shifts in climate patterns as predicted by IPCC. 12,13 …”

New records of the snow bass Serranus chionaraia (Perciformes: Serranidae) confirm an established population in the Brazilian Province

“…Brazil harbours the worldʼs largest continuous rhodolith beds (Amado‐Filho et al ., ). These complex habitats cover almost the entire continental shelf, mainly in the mesophotic zone (30–150 m depth), the tops of seamounts and the shelf around oceanic islands (Horta et al ., ). Brief explorations of mesophotic environments on the Brazilian coast (Carvalho‐Filho & Ferreira, ; Simon et al ., ; Smith‐Vaniz et al ., ; present study) and elsewhere have repeatedly demonstrated that many new species and occurrences remain to be discovered in this low‐light zone.…”