Eutrofização do Reservatório Cruzeta na bacia representativa do rio Seridó RN

Eutrophication has been listed as one of the main problems of water pollution on a global level. In the Brazilian semi-arid areas this problem takes even greater proportions due to characteristical water scarcity of the region. It is extremely important to the predictive eutrophication models development and to the reservoirs management in the semi-arid region, studies that promotes understanding of the mechanisms responsible for the expansion and control of algae blooms, essential for improving the water quality of these environments. The present study had as its main aims, evaluate the temporal pattern of trophic state, considering the influence of nutrients (N and P) and the light availability in the water column in the development of phytoplankton biomass, and perform the mathematical modelling of changes in phosphorus and chlorophyll a concentrations in the Cruzeta man-made lake located on Seridó, a typical semi-arid region of Rio Grande do Norte. To this, a fortnightly monitoring was performed in the reservoir in 05 stations over the months of March 2007 to May 2008. Were measured the concentrations of total phosphorus, total organic nitrogen, chlorophyll a, total, fixed and volatile suspended solids, as well as the measure of transparency (Secchi) and the profiles of photosynthetic active radiation (PAR), temperature, pH, dissolved oxygen and electrical conductivity in the water column. Measurements of vertical profiles have shown some periods of chemical and thermal stratification, especially in the rainy season, due to increased water column depth, however, the reservoir can be classified as warm polimitic. During the study period the reservoir was characterized as eutrophic considering the concentrations of phosphorus and most of the time as mesotrophic, based on the concentrations of chlorophyll a, according to the Thornton & Rast (1993) classification. The N:P relations suggest N limitation, conversely, significant linear relationship between the algae biomass and nutrients (N and P) were not observed in our study. However, a relevant event was the negative and significant correlation presented by Kt and chlorophyll a (r ² = 0.83) at the end of the drought of 2007 and the rainy season of 2008, and the algal biomass collapse observed at the end of the drought season (Dec/07). The equation used to simulate the change in the total phosphorus was not satisfactory, being necessary inclusion of parameters able to increase the power of the model prediction. The chlorophyll a simulation presented a good adjustment trend, however there is a need to check the calibrated model parameters and subsequent equation validation

O efeito do regime hidrológico do semiárido na composição de espécies durante dominância de cianobactérias em um reservatório tropical

The potentially toxic cyanobacterial blooms in water bodies are spread across the globe, resulting in the loss of water quality and adverse effects on human health. In arid and semiarid regions, the hydrologic regime characterized by an annual cycle of drought and rain, change the volume and the retention time of the reservoir. Such changes affect the limnological characteristics and causing changes in composition and biomass community of cyanobacteria. The reservoir Cruzeta (Zmax = 8.7 m) is a eutrophic water supply source located in the semiarid tropical (Northeast Brazil). Raised the hypothesis that the hydrological regime of semi-arid tropical is a determining factor in the availability of resources in eutrophic water sources, which influences the composition of dominant species of cyanobacteria. The aim of this study was to analyze the changes in biomass and species composition of cyanobacteria for two annual hydrological cycles and evaluate factors drivers. The study was divided into five distinct periods (dry 2010, rain 2011, dry 2011, rain 2012, dry 2012). The dominant group found in all periods was Cyanobacteria (99% of total biomass), which contributed to the low diversity. The filamentous species Cylindrospermopsis raciborskii was present at both points in almost every study. The colonial species Microcystis panniformis and Sphaerocavum brasiliensis dominated only in periods with lower volumes of water. The diatoms contribute more to the biomass during the period of severe drought. The point near the dam (P1) had phytoplankton biomass larger than the point near the tributary (P2). The dominant species of colonial cyanobacteria lasted until the overflow in P1, and P2 this dominance was until the first rains. The redundancy analysis indicated that physical factors such as light availability and water level were the main factors driving the seasonal succession of phytoplankton. The composition of phytoplankton in spring was alternated by species of filamentous cyanobacteria in conditions of poor stability of the water column, such as Cylindrospermopsis raciborskii, and colonial species under conditions of high stability of the water column, such as Microcystis panniformis and Sphaerocavum brasiliensis. The extremes of torrential rains and severe droughts, governed by the hydrological regime of the semi-arid region led to the availability of resources in the watershed, directing the spatial and temporal dynamics of phytoplankton in the reservoir Cruzeta

O que controla o crescimento do Fitoplâncton em lagoas costeiras tropicais? um modelo para a lagoa de Extremoz (RN)

The phytoplankton growth is dependent of several abiotic (nutrients, temperature) and biotic (predation by zooplankton) variables. In this work, a mathematical model was developed in Stella software to understand the planktonic dynamics of Extremoz Lagoon (RN) and to simulate scenarios of different environmental conditions. Data were collected monthly at two points of the lagoon. The state variables are phytoplankton and zooplankton and forcing variables are nitrogen, phosphorus and temperature. The results show that: a) the model are well coupled, especially when some constants assume different values; b) simulated nutrient concentrations reduction decreases phytoplankton biomass, but the increase of nutrients does not stimulate the growth; c) changes in the temperature does not change the phytoplankton biomass; d) changes in zooplankton biomass affect directly and reduces the phytoplankton, indicating a topdown control mechanism; e) changes in the nutrient concentration modified the biomass of zooplankton suggesting a rapid flow of energy between nutrients, phytoplankton and zooplankton and a ecosystem likely arranged in an inverted pyramid (higher concentration of zooplankton than phytoplankton)

Biomonitoramento da qualidade da água e ações em educação ambiental em dois açudes da bacia hidrográfica Apodi-Mossoró, RN

Water scarcity is a reality for the inhabitants of the Brazilian semiarid region. The problem, in quantitative terms , is caused due to local climatic conditions due mostly to a water deficit. Qualitatively, results of multiple uses and resulting contamination by human activities. Eutrophication is presented as a threat to the sustainable use of water resources, in order to favor the predominance of dense populations of cyanobacteria, which can be potentially harmful to human health. The aim of this study is to understand the population dynamics of phytoplankton and cyanobacteria to assess water quality of reservoirs Santa Cruz do Apodi and Pau dos Ferros belonging to bacia Apodi Mossoró-RN . Water samples were collected monthly between October 2011 and May 2012 in reservoirs Santa Cruz do Apodi and Pau dos Ferros, in this latter , in Jan/12 we performed a diel profile . The abiotic variables obtained in the field and in the laboratory were: water temperature , dissolved oxygen , pH , turbidity , transparency , total nitrogen and total phosphorus . Phytoplankton samples were collected with a plankton net and bottle of Van dorn . Were performed : identification , quantification , calculation of biovolume , classification into functional groups and index calculation phytoplankton assembly ( Q ) , cyanotoxins were quantified by ELISA . Statistical analyzes supported the evaluation of the dynamics between biotic and abiotic factors. A questionnaire was conducted to examine the conceptions of the population, education professionals and students. The reservoir of Pau dos Ferros, shallow , turbid and eutrophic showed dominance of the functional group SN throughout the sample period . The phytoplankton biomass ranged from 20 to 70 mm ³ . L - 1, the lowest values coincided with the increase of the mixing zone and transparency, which contributed to the occurrence of a change in species composition phytoplankton . The application of the index Q proved relevant, the reservoir of Pau dos Ferros , depending on the species present , was classified ecologically as bad for almost the entire sample period . The reservoir Santa Cruz do Apodi showed low biomass ( 0.04 and 4.31 mm ³ . L - 1 ) and greater diversity in the phytoplankton composition . According to the index assembly (Q ), it showed moderate condition during most of the period influenced by different functional groups of typical meso- eutrophic environment (K S0, H1, C, F , J , E, D and N) . Associations of diatoms and green algae D and X1 succeeded populations of cyanobacteria in periods marked by greater instability in the system , caused by wind or rain. In summary , the occurrence of drought has a direct influence on the hydrological conditions of the reservoirs , in general, these events, reducing the reservoir level is directly related to decreased water quality and increased density of phytoplankton occurring predominance of cyanobacteria , the index Q reflected well to changes in phytoplankton composition , being a good indicator for biomonitoring of reservoirs in this study and survey of previous conceptions showed the need to work on environmental awareness for the preservation of water resources by conducting workshops for Environmental Education

Geoprocessamento de dados meteo-oceonográficos (cor do oceano e temperatura da superfície do mar) aplicado ao monitoramento ambiental na costa setentrional do Rio Grande do Norte

Orbital remote sensing has been used as a beneficial tool in improving the knowledge on oceanographic and hydrodynamic aspects in northern portion of the continental shelf of Rio Grande do Norte, offshore Potiguar Basin. Aspects such as geography, temporal and spatial resolution combined with a consistent methodology and provide a substantial economic advantage compared to traditional methods of in situ data collecting. Images of the Moderate Resolution Imaging Spectroradiometer (MODIS) sensor onboard NASA's AQUA satellite were obtained to support systematic data collections related to the campaign of environmental monitoring and characterization of Potiguar Basin, held in May 2004. Images of Total Suspension Matter (TSM) and values of radiance standard were generated for the calculation of concentrations of total suspension matter (TSM), chlorophyll-a and sea surface temperature (SST). These data sets were used for statistical comparisons between measures in situ and satellite estimates looking validate algorithms or develop a comprehensive regional approach empirically. AQUA-MODIS images allowed the simultaneous comparison of two-dimensional water quality (total suspension matter), phytoplankton biomass (chlorophyll-a) variability and physical (temperature). For images of total suspension matter, the generated models showed a good correlation with the field data, allowing quantitative and qualitative analysis. The images of chlorophyll-a showed a consistent correlation with the in situ values of concentration. The algorithms adjusted for these images obtained a correlation coefficient fairly well with the data field in order that the sensor can be having an effect throughout the water column and not just the surface. This has led to a fit between the data of chlorophyll-the integration of the average sampling interval of the entire water column up to the level of the first optical depth, with the data generated from the images. This method resulted in higher values of chlorophyll concentration to greater depths, due to the fact that we are integrating more values of chlorophyll in the water column. Thus we can represent the biomass available in the water column. Images SST and SST measures in situ showed a mean difference DT (SST insitu - SST sat) around -0.14 ° C, considered low, making the results very good. The integration of total suspension matter, chlorophyll-a, the temperature of the sea surface (SST) and auxiliary data enabled the recognition of some of the main ways to fund the continental shelf. The main features highlighted were submerged canyons of rivers Apodi and Açu, some of the lines and beachrocks reefs, structural highs and the continental shelf break which occurs at depths around -60 m. The results confirmed the high potential for use of the AQUA-MODIS images to environmental monitoring of sea areas due to ease of detection of the field two-dimensional material in suspension on the sea surface, temperature and the concentration of chlorophyll-a

Zooplankton fluctuations in Jurumirim Reservoir (São Paulo, Brazil): a three-year study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Variabilidade temporal e meridional de estimativas de Satélite da concentração de clorofila superficial na plataforma continental brasileira

Forecast of biological consequences of climate changes depend on both long-term observations and the establishment of carbon budgets within pelagic ecosystems, including the assessment of biomasses and activities of all players in the global carbon cycle. Approximately 25% of oceanic primary happen over continental shelves, so these are important sites for studies of global carbon dynamics. The Brazilian Continental Shelf (BCS) has sparse and non-systematic in situ information on phytoplankton biomass, making products derived from ocean color remote sensing extremely valuable. This work analyzes chlorophyll concentration (Chl) estimated from four ocean color sensors (CZCS, OCTS, SeaWiFS and MODIS) over the BCS, to compare Chl and annual cycles meridionally. Also, useful complementary ocean color variables are presented. Chl gradients increased from the central region towards north and south, limited by estuarine plumes of Amazon and La Plata rivers, and clear annual Chl cycles appear in most areas. In southern and central areas, annual cycles show strong seasonal variability while interannual and long-term variability are equally important in the remaining areas. This is the first comparative evaluation of the Chl over the BCS and will aid the understanding of its long-term variability; essential initial step for discussions of climate changes.

Assembléias zooplanctônicas (Cladocera, Copepoda e Rotifera) e condiçoes limnolócas no gradiente longitudinal barragem-jusante do reservatório de Itaipu, rio Paraná (Brasil, Paraguai e Argentina)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Resposta do perifíton aos pulsos de enriquecimento em níveis crescentes de fósforo e nitrogênio em represa tropical mesotrófica (Lago das Ninféias, São Paulo)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Estrutura e dinâmica da comunidade fitoplanctônica no período de cinco anos em ambiente mesotrófico (Lago das Ninfeias), Parque Estadual das Fontes do Ipiranga, São Paulo

Pós-graduação em Ciências Biológicas (Biologia Vegetal) - IBRC

Qualidade das águas superficiais e avaliação do estado trófico do Rio Arari (Ilha de Marajó, norte do Brasil)

A deterioração da qualidade da água pode ser causada tanto por resultado da pressão antrópica sobre os ambientes aquáticos em maiores escalas, como por fatores naturais em menores escalas, tal como ocorre em parte da bacia hidrográfica do Rio Arari (Ilha de Marajó, Pará). Este artigo teve como objetivo a avaliação da qualidade das águas superficiais e o estado trófico do Rio Arari, no trecho entre Santana e Cachoeira do Arari, considerando as variações temporais e espaciais de variáveis físicas, químicas e biológicas da água em dois períodos hidrológicos distintos de 2009: descarga máxima (abril e maio) e descarga mínima (setembro e novembro). Os Índices de Qualidade da Água (IQA) e Estado Trófico (IET) foram determinados simultaneamente em amostras de água superficial durante 12 horas consecutivas nas três estações de coleta ao longo do Rio Arari. Os valores do IQA variaram entre "Ruim" e "Regular", e estão provavelmente relacionadas aos elevados níveis de coliformes fecais, baixas concentrações de oxigênio dissolvido e pH ácido do Rio Arari. Conforme o IET, o rio pode ser classificado como supereutrófico e hipereutrófico, reflexo da grande disponibilidade de nutrientes (e.g. fósforo) e elevada biomassa fitoplanctônica em termos de clorofila a. O Rio Arari está sob um processo de eutrofização natural, visto que as fontes de contaminação antrópica ainda são incipientes, mas elas podem contribuir para um processo de longo prazo de eutrofização artificial.

Variação espacial do grau de trofia e da biomassa fitoplanctônica no reservatório de Itupararanga (São Paulo, Brasil)

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Sensoriamento remoto multifonte aplicado na detecção do fitoplâncton em águas interiores

Blooms of phytoplankton can be a risk to human health and aquatic biota, so the adoption of monitoring methods of phytoplankton and mechanisms for preventing its occurrence are needed. Thus, traditional monitoring methods could be more effective if complemented by approaches using the optical properties of phytoplankton pigments by means of Remote Sensing. In order to evaluate the potential of multi-scale remote sensing for detection of the phytoplankton activity, a study area was selected in Nova Avanhandava reservoir, located in the Tiete River, SP. For this analysis, hyperspectral field data and multispectral images of low and medium spatial resolution (Modis and RapidEye) were acquired and were related to indicator limnological variables of phytoplankton behavior; chlorophyll a and phycocyanin. The results show that a specific spectral band of RapidEye system (690-730 nm) allowed detect chlorophyll a and to evaluate the phytoplankton biomass, however hyperspectral data are needed to detect the phycocyanin pigment, indicative of cyanobacteria.

Does the plankton community follow the horizontal water quality heterogeneity in a tropical urban reservoir (Guarapiranga reservoir, Sao Paulo, Brazil)?

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Temporal variability of chlorophyll-a in the São Vicente estuary

Estuaries are extremely dynamic environments that are vulnerable to anthropogenic alterations. Thus, monitoring phytoplankton abundances and composition is an essential tool for the prediction of eutrophication and its effects on coastal ecosystems. Phytoplankton biomass, as chlorophyll-a, in the São Vicente estuary (Brazil) varies in response to tidal cycles and seasonal rainfall. Objectives. To present two datasets designed to assess the relationship between chlorophyll-a and changes in water turbidity driven by tide and rain. Methods. Weekly observations were made in the shallow embayment (February to September 2008; site 1) and observations recorded on alternate days (summer 2010, site 2). Results. At site 1, turbidity differed between high and low tides, but on most days was over 3000 RU, maintaining moderate chlorophyll-a levels (4 mg.m-3) and only two blooms developed during low turbidity. Site 2 mean turbidity was 1500 RU, nutrient level was higher during neap tides and phytoplankton blooms were mainly observed at the end of neap tides at 15-day intervals, dominated by chain-forming diatoms and occasionally flagellates and pennate diatoms. Conclusions. Taxonomic composition of the blooms was different and their frequency altered by events characterized by intense freshwater discharges from the Henry Borden Hydroelectric Dam (> 9*106.m³), inhibiting phytoplankton accumulation during neap tide periods.