Seagrass and submerged aquatic vegetation (VAS) habitats off the Coast of Brazil: state of knowledge, conservation and main threats

Seagrass meadows are among the most threatened ecosystems on earth, raising concerns about the equilibrium of coastal ecosystems and the sustainability of local fisheries. The present review evaluated the current status of the research on seagrasses and submerged aquatic vegetation (SAV) habitats off the coast of Brazil in terms of plant responses to environmental conditions, changes in distribution and abundance, and the possible role of climate change and variability. Despite an increase in the number of studies, the communication of the results is still relatively limited and is mainly addressed to a national or regional public; thus, South American seagrasses are rarely included or cited in global reviews and models. The scarcity of large-scale and long-term studies allowing the detection of changes in the structure, abundance and composition of seagrass habitats and associated species still hinders the investigation of such communities with respect to the potential effects of climate change. Seagrass meadows and SAV occur all along the Brazilian coast, with species distribution and abundance being strongly influenced by regional oceanography, coastal water masses, river runoff and coastal geomorphology. Based on these geomorphological, hydrological and ecological features, we characterised the distribution of seagrass habitats and abundances within the major coastal compartments. The current conservation status of Brazilian seagrasses and SAV is critical. The unsustainable exploitation and occupation of coastal areas and the multifold anthropogenic footprints left during the last 100 years led to the loss and degradation of shoreline habitats potentially suitable for seagrass occupation. Knowledge of the prevailing patterns and processes governing seagrass structure and functioning along the Brazilian coast is necessary for the global discussion on climate change. Our review is a first and much-needed step toward a more integrated and inclusive approach to understanding the diversity of coastal plant formations along the Southwestern Atlantic coast as well as a regional alert the projected or predicted effects of global changes on the goods and services provided by regional seagrasses and SAV

Microorganismos em praias arenosas expostas: importância, aspectos metodológicos e estado da arte para o sul do Brasil

We adopt a wide concept of marine microorganisms (bacteria, microalgae, protozoan, fungi, and virus), and present their general characteristics, controlling factors and information on the role of these organisms as primary producers, mineralizers and consumers. Methodological aspects regarding the sampling program, sample conservation, counting and biomass estimation are also discussed. At the exposed sand beaches of the southern Brazilian coast, high primary production occurrs due to surf zone diatom accumulation. This is a poorly studied phenomenon, and detailed research is necessary in order to quantify the production and consumption processes, and to determine the fate ofthe organic matter produced in these environments. Key-words: diatom, protist, bacterium, microbenthos, surf-zone, southern BrazilAdotamos um conceito amplo de microorganismos marinhos (bactérias, microalgas, protozoários, fungos e vírus), e apresentamos suas características gerais, o seu papel como produtores primários, remineralizadores e consumidores, e os seus principais fatores controladores. Aspectos metodológicos do plano amostral, coleta e conservação de amostras, contagem e estimativa de biomassa dos diversos grupos de microorganismos são abordados. No litoral sul do Brasil, constatamos que as praias arenosas expostas apresentam alta produção primária devido à acumulação de diatomáceas da zona de arrebentação. A caracterização deste fenômeno encontra-se em estágio inicial, fazendo-se necessários estudos detalhados para quantificar os processos de produção, consumo e o destino da matéria orgânica formada nestes ambientes