CIANOBACTÉRIAS E CIANOTOXINAS EM AMBIENTES AQUÁTICOS: uma breve revisão sobre os principais métodos detecção, remoção e impactos sobre a saúde humana = CYANBACTERIA AND CYANOTOXINS IN AQUATIC ENVIRONMENTS: a short review on the main methods of detection, removal and impacts on human health

Muitos corpos hídricos têm sido degradados devido à interferência humana. A poluição causada pelas atividades antrópicas vem comprometendo a qualidade da água e promovendo eventos de eutrofização, afetando toda estrutura trófica do ambiente, podendo assim acarretar na proliferação de cianobactérias tóxicas. Nesse sentido, o conhecimento sobre esses organismos é de grande importância, principalmente em corpos hídricos com usos múltiplos. Esta pesquisa representa uma revisão de trabalhos publicados envolvendo qualidade ambiental e ecolotoxicologia aquática, tendo como foco estudos relacionados às cianobactérias e cianotoxinas. Para o trabalho foram analisados livros textos e artigos publicados entre 2010 e 2020 em periódicos nacionais e internacionais. Na literatura publicada nos últimos anos são apresentadas as principais metodologias envolvidas na detecção e remoção de cianotoxinas, além de bioensaios ecotoxicológicos. Fica evidente a importância do tratamento de efluentes e controle das fontes de poluição difusas e pontuais no ecossistema promovendo a melhoria da qualidade da água e controle de cianobactérias.ABSTRACTCyanobacteria play an important role among producers in aquatic ecosystems, however when associated with eutrophication they become an ecological and public health problem. The problem involving cyanobacteria is the blooming of potentially toxic strains. The present work aims to present and discuss the problems related to the proliferation of cyanobacteria in limnological environments, and its consequences for dynamics in the environment and effects on environmental health. In this sense, knowledge about these organisms is of great importance, especially in water bodies with multiple uses. This research represents a review of published works involving environmental quality and aquatic ecotoxicology, focusing on studies related to cyanobacteria and cyanotoxins. For the present work, textbooks and articles published between 2010 and 2020 in national and internationaljournals were analyzed. In the literature published in recent years, the main methodologies involved in the detection and removal of cyanotoxins are presented, in addition to ecotoxicological bioassays. The study of cyanobacteria and their metabolites comprises an area of interest that reaches a greater dimension when impacts on the quality of water supply are evident, thus the importance of treating effluents and controlling pollution sources in the ecosystem is evident, promoting improvement and maintenance the quality of the water bodies.

Behavioral effects of the neurotoxin ß-N-methylamino-L-alanine on the mangrove rivulus (Kryptolebias marmoratus) larvae

Mangrove rivulus, Kryptolebias marmoratus, is a hermaphrodite fish capable of self-fertilization. This particularity allows to naturally produce highly homozygous and isogenic individuals. Despite the low genetic diversity, rivulus can live in extremely variable environments and adjust its phenotype accordingly. This species represents a unique opportunity to clearly distinguish the genetic and non-genetic factors implicated in adaptation and evolution, such as epigenetic mechanisms. It is thus a great model in aquatic ecotoxicology to investigate the effects of xenobiotics on the epigenome, and their potential long-term impacts. In the present study, we used the mangrove rivulus to investigate the effects of the neurotoxin ß-N-methylamino-L-alanine (BMAA) on larvae behaviors after 7 days exposure to two sub-lethal concentrations. Results show that BMAA can affect the maximal speed and prey capture (trials and failures), suggesting potential impacts on the organism’s fitness.

Common Duckweeds as a Model System for Climate Change Impact Assessment

Common duckweeds – Lemna – are free-floating aquatic macrophytes belonging to Lemnaceae family. They occur universally, in tropical and temperate zones and are enabled to grow in stagnant, slow-flowing, nutrient-enriched waters. They have an ability to grow over a wide range of temperatures (6 – 33 0C) and pH (optimum 5.5 – 7.5). Lemna species also manifest a characteristic macrophyte community in association with plants functioning as a dominant primary producer. Asexual mode of reproduction is exclusive and therefore, all resources are directed towards vegetative growth. Structure wise they show leaflets (frond) and root-like diffuse form. This simple morphological and physiological form offers special scientific and engineering properties – reflected in easy handling and manipulation under laboratory conditions. As a result they are regarded as a model plant system for a number of chemical and biogeochemical studies. Climate change affects plant growth and physiology. For example, increasing atmospheric concentrations of carbon dioxide (CO2) and ozone (O3) or increase in ultraviolet (UV) radiation (due to the thinning of the ozone layer) can have pronounced effects on the growth and development of plants. In many instances the decrease in growth rate can create disturbances in photosynthetic processes. In the recent past there has been a surge in the interest in looking for alternative remediation technologies to meet formidable demands of polluting materials and situations. One such approach is phytoremediation – the use of plants and associated microbes for environmental cleanup. Cardinal points in favour of such an approach are – cost-effectiveness, natural energy-driven and minimal capital and running costs. Potency of Lemna spp. as a phytoremediation agent as well as its limitations haven dealt with in details in literature. Moreover, Lemna spp. are accepted and highly standardized as test organisms in aquatic ecotoxicology. The authors have shown earlier that Lemna spp. can play a vital role in combating pollution burden in a glaring local situation of river pollution. However, the recent trend in research indicates that Lemna spp (duckweeds at large) can play a critical and sensitive role in being an indicator of overt and subtle climate change. The following is an attempt to take a review of such recent trends.