Uso de quitina e quitosana como adsorventes de amônia de efluentes aquícolas: revisão de literatura / Use of chitin and quitosan as adsorvents of ammonia of aquaculture effluents: a literature review / Uso de quitina y quitosana como adsorbentes de amonia de efluentes acuícolas: revisión de literatura

Os resíduos provenientes da aquicultura são derivados da ração e da excreção dos peixes e podem estar sedimentados, suspensos ou dissolvidos, ocasionando elevados valores de DBO, DQO, nitrogênio e fósforo. A produção de camarões no Brasil tem gerado elevadas quantidades de resíduos sólidos, tendo em vista que os exoesqueletos dos camarões correspondem a cerca de 40% do seu peso total, resultando num forte impacto ambiental. Diversas pesquisas envolvendo a quitina estão sendo desenvolvidas na área de tratamento de água, devido principalmente a sua capacidade de formar filme, sendo utilizada em sistemas filtrantes. Este polissacarídeo também pode ser utilizado como agente floculante no tratamento de efluentes, como adsorvente na clarificação de óleos, e principalmente na produção de quitosana. Atualmente a quitosana possui aplicações multidimensionais, desde áreas como a nutrição humana, biotecnologia, ciência dos materiais, indústria farmacêutica, agricultura, terapia genética e proteção ambiental. A quitosana é muito eficiente na remoção de poluentes em diferentes concentrações. Apresenta alta capacidade e grande velocidade de adsorção, boa eficiência e seletividade tanto em soluções que possuem altas ou baixas concentrações. O uso da biotecnologia, através do processo de adsorção utilizando adsorventes naturais e baratos, como a quitina e quitosana, minimiza os impactos ambientais da aquicultura tanto em relação aos provocados pelo lançamento de efluentes no meio ambiente quanto aos causados pelo descarte inadequado dos resíduos do processamento de camarões.(AU)

Aquaculture residues are derived from fish feed and excretion and may be sedimented, suspended or dissolved, resulting in high BOD, COD, nitrogen and phosphorus values. Shrimp production in Brazil has generated high amounts of solid waste, since shrimp exoskeletons account for about 40% of their total weight, resulting in a strong environmental impact. Several researches involving chitin are being developed in the area of water treatment, mainly due to its ability to form film, being used in filter systems. This polysaccharide can also be used as a flocculating agent in the treatment of effluents, as an adsorbent in the clarification of oils, and especially in the production of chitosan. Currently, chitosan has multidimensional applications, from areas such as human nutrition, biotechnology, materials science, pharmaceutical industry, agriculture, gene therapy and environmental protection. Chitosan is very efficient in the removal of pollutants at different concentrations. It presents high capacity and high adsorption velocity, good efficiency and selectivity both in solutions that have high or low concentrations. The use of biotechnology, through the adsorption process using natural and cheap adsorbents such as chitin and chitosan, minimizes the environmental impacts of aquaculture both in relation to those caused by the release of effluents into the environment and those caused by the inappropriate disposal of processing residues of shrimps.(AU)

Los residuos procedentes de la acuicultura se derivan de la ración y de la excreción de los peces y pueden estar sedimentados, suspendidos o disueltos, ocasionando elevados valores de DBO, DQO, nitrógeno y fósforo. La producción de camarones en Brasil ha generado grandes cantidades de residuos sólidos, teniendo en cuenta que los exoesqueletos de los camarones corresponden a cerca del 40% de su peso total, resultando en un fuerte impacto ambiental. Varias investigaciones involucrando la quitina se están desarrollando en el área de tratamiento de agua, debido principalmente a su capacidad de formar película, siendo utilizada en sistemas filtrantes. Este polisacárido también puede ser utilizado como agente floculante en el tratamiento de efluentes, como adsorbente en la clarificación de aceites, y principalmente en la producción de quitosana. Actualmente la quitosana posee aplicaciones multidimensionales, desde áreas como la nutrición humana, biotecnología, ciencia de los materiales, industria farmacéutica, agricultura, terapia genética y protección ambiental. La quitosana es muy eficiente en la eliminación de contaminantes en diferentes concentraciones. Presenta alta capacidad y gran velocidad de adsorción, buena eficiencia y selectividad tanto en soluciones que poseen altas o bajas concentraciones. El uso de la biotecnología, a través del proceso de adsorción utilizando adsorbentes naturales y baratos, como la quitina y quitosana, minimiza los impactos ambientales de la acuicultura tanto en relación a los provocados por el lanzamiento de efluentes en el medio ambiente en cuanto a los causados por el descarte inadecuado de los residuos del procesamiento de camarones.(AU)

Massive Southern Ocean phytoplankton bloom fed by iron of possible hydrothermal origin.

Primary production in the Southern Ocean (SO) is limited by iron availability. Hydrothermal vents have been identified as a potentially important source of iron to SO surface waters. Here we identify a recurring phytoplankton bloom in the high-nutrient, low-chlorophyll waters of the Antarctic Circumpolar Current in the Pacific sector of the SO, that we argue is fed by iron of hydrothermal origin. In January 2014 the bloom covered an area of ~266,000 km2 with depth-integrated chlorophyll a > 300 mg m-2, primary production rates >1 g C m-2 d-1, and a mean CO2 flux of -0.38 g C m-2 d-1. The elevated iron supporting this bloom is likely of hydrothermal origin based on the recurrent position of the bloom relative to two active hydrothermal vent fields along the Australian Antarctic Ridge and the association of the elevated iron with a distinct water mass characteristic of a nonbuoyant hydrothermal vent plume.

Insights into the mechanism of cyanobacteria removal by the algicidal fungi Bjerkandera adusta and Trametes versicolor.

Fungal mycelia can eliminate almost all cocultured cyanobacterial cells within a short time. However, molecular mechanisms of algicidal fungi are poorly understood. In this study, a time-course transcriptomic analysis of algicidal fungus Bjerkandera adusta T1 was applied to investigate gene expression and regulation. A total of 132, 300, 422, and 823 differentially expressed genes (DEGs) were identified at 6, 12, 24, and 48 hr, respectively. Most DEGs exhibited high endopeptidase activity, cellulose catabolic process, and transmembrane transporter activity by using Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses. Many decomposition genes encoding endopeptidases were induced a little later in B. adusta T1 when compared with previously investigated algicidal fungus Trametes versicolor F21a. Besides, the accumulated expression of Polysaccharide lyases8 (PL8) gene with peptidoglycan and alginate decomposition abilities was greatly delayed in B. adusta T1 relative to T. versicolor F21a. It was implied that endopeptidases and enzymes of PL8 might be responsible for the strong algicidal ability of B. adusta T1 as well as T. versicolor F21a.

Composition of dissolved organic matter controls interactions with La and Al ions: Implications for phosphorus immobilization in eutrophic lakes.

Applications of aluminium (Al) salt or lanthanum (La) modified bentonite (LMB) have become popular methodologies for immobilizing phosphorus (P) in eutrophic lakes. The presence of humic substances, has been shown to inhibit this form of treatment due to the complexation with La/Al. However, the effects of other dissolved organic matter (DOM), especially that derived from phytoplankton (the dominant source in eutrophic lakes) are unknown. In this study, the interaction with La/Al of Suwannee River Standard Humic Acid Standard II (SRHA) and algae-derived DOM (ADOM) were investigated and compared. Differed to SRHA which was dominated by polyphenol-like component (76.8%, C1-SRHA), majority in ADOM were protein-like substance, including 41.9% tryptophan-like component (C2-ADOM) and 21.0% tyrosine-like component (C3-ADOM). Two reactions of complexation and coprecipitation were observed between SRHA/ADOM and La/Al. Complexation dominated at low metal inputs less than 10 µM and coprecipitation was the main reaction at higher metal inputs. For ADOM, the tryptophan-like component (C2-ADOM) was the important component to react with metal. The reaction rate for C2-ADOM with La were about two-third of that for C1-SRHA, indicating that the influence of C2-ADOM was significant during the P immobilization by La/Al-based treatment in eutrophic lakes. The P removal data in the presence of ADOM confirmed the significant inhibition of ADOM. In addition, based on the composition of coprecipitates and relatively biodegradable character of tryptophan-like substances (C2-ADOM), the coprecipitation of ADOM was assumed to reduce the stability of precipitated P in eutrophic lakes. The release of P from the potential biodegradation of the coprecipitates and thus the possible decline of the performance of P immobilization by La/Al-based treatments is an important work in the future.

Can microcystins affect zooplankton structure community in tropical eutrophic reservoirs? / Microcistinas podem afetar a estrutura da comunidade zooplanctônica em reservatórios eutróficos tropicais?

Abstract The aim of our study was to assess whether cyanotoxins (microcystins) can affect the composition of the zooplankton community, leading to domination of microzooplankton forms (protozoans and rotifers). Temporal variations in concentrations of microcystins and zooplankton biomass were analyzed in three eutrophic reservoirs in the semi-arid northeast region of Brazil. The concentration of microcystins in water proved to be correlated with the cyanobacterial biovolume, indicating the contributions from colonial forms such as Microcystis in the production of cyanotoxins. At the community level, the total biomass of zooplankton was not correlated with the concentration of microcystin (r2 = 0.00; P > 0.001), but in a population-level analysis, the biomass of rotifers and cladocerans showed a weak positive correlation. Cyclopoid copepods, which are considered to be relatively inefficient in ingesting cyanobacteria, were negatively correlated (r2 = – 0.01; P > 0.01) with the concentration of cyanotoxins. Surprisingly, the biomass of calanoid copepods was positively correlated with the microcystin concentration (r2 = 0.44; P > 0.001). The results indicate that allelopathic control mechanisms (negative effects of microcystin on zooplankton biomass) do not seem to substantially affect the composition of mesozooplankton, which showed a constant and high biomass compared to the microzooplankton (rotifers). These results may be important to better understand the trophic interactions between zooplankton and cyanobacteria and the potential effects of allelopathic compounds on zooplankton.

Resumo Com o objetivo de avaliar se as cianotoxinas (microcistinas) podem afetar a composição da comunidade zooplanctônica, levando à dominância de formas microzooplanctônicas (protozoários e rotiferos), as variações nas concentrações de microcistina e a biomassa do zooplâncton foram analisadas em três reservatórios eutróficos na região semi-árida do nordeste brasileiro. A concentração de microcistinas na água esteve correlacionada com o biovolume de cianobactérias, indicando a contribuição de formas coloniais como Microcystis na produção de cianotoxinas. A nível de comunidade, a biomassa total do zooplâncton não apresentou correlacão com a concentração de microcistina (r2 = 0.00; P > 0.001), mas em uma análise a nível de populações, a biomassa de rotíferos e cladóceros apresentou uma fraca correlação positiva. Copépodos Cyclopoida, os quais são considerados relativamente ineficientes na ingestão de cianobactérias, estiveram negativamente correlacionados com a concentração de microcistinas (r2 = - 0.01; P > 0.01). Surpreendentemente, a biomassa de copépodos Calanoida foi positivamente correlacionada com a concentração de cianotoxinas (r2 = 0.44; P > 0.001). Os resultados indicam que mecanismos de controle alelopáticos (efeitos negativos da microcistina sobre o zooplâncton) parecem não afetar substancialmente a composição do mesozooplâncton, que apresentou uma alta e constante biomassa, quando comparada à biomassa do microzooplâncton (rotíferos). Esses resultados podem ser importantes para um melhor entendimento das interações tróficas entre o zooplâncton e cianobactérias, e do efeito potencial de compostos alelopáticos sobre o zooplâncton.

Role of resting cysts in Chilean Alexandrium catenella dinoflagellate blooms revisited.

The detection of sparse Alexandrium catenella-resting cysts in sediments of southern Chilean fjords has cast doubts on their importance in the recurrence of massive toxic dinoflagellate blooms in the region. The role of resting cysts and the existence of different regional Chilean populations was studied by culturing and genetic approaches to define: (1) cyst production; (2) dormancy period; (3) excystment success; (4) offspring viability and (5) strain mating compatibility. This study newly revealed a short cyst dormancy (minimum 69 days), the role of key abiotic factors (in decreasing order salinity, irradiance, temperature and nutrients) controlling cyst germination (max. 60%) and germling growth rates (up to 0.36-0.52div.day-1). Amplified fragment length polymorphism (AFLP) characterization showed significant differences in genetic distances (GD) among A. catenella populations that were primarily determined by the geographical origin of isolates and most likely driven by oceanographic dispersal barriers. A complex heterothallic mating system pointed to variable reproductive compatibility (RCs) among Chilean strains that was high among northern (Los Lagos/North Aysén) and southern populations (Magallanes), but limited among the genetically differentiated central (South Aysén) populations. Field cyst surveys after a massive 2009 bloom event revealed the existence of exceptional high cyst densities in particular areas of the fjords (max. 14.627cystscm-3), which contrast with low cyst concentrations (<221.3cystscm-3) detected by previous oceanographic campaigns. In conclusion, the present study suggests that A. catenella resting cysts play a more important role in the success of this species in Chilean fjords than previously thought. Results from in vitro experiments suggest that pelagic-benthic processes can maintain year-round low vegetative cell concentrations in the water column, but also can explain the detection of high cysts aggregations after the 2009-bloom event. Regional drivers that lead to massive outbreaks, however, are still unknown but potential scenarios are discussed.

Chlorophyll catalyse the photo-transformation of carcinogenic benzo[a]pyrene in water.

Algal blooms cause great damage to water quality and aquaculture. However, this study showed that dead algal cells and chlorophyll could accelerate the photo-transformation of benzo[a]pyrene (BaP), a ubiquitous and persistent pollutant with potently mutagenic and carcinogenic toxicities, under visible light irradiation. Chlorophyll was found to be the major active substance in dead algal cells, and generated a high level of singlet oxygen to catalyse the photo-transformation of BaP. According to various BaP metabolites formed, the degradation mechanism was proposed as that chlorophyll in dead algal cells photo-oxidized BaP to quinones via photocatalytic generation of singlet oxygen. The results provided a good insight into the role of chlorophyll in the photo-transformation of organic contaminants and could be a possible remediation strategy of organic pollutants in natural environment.

Iron supply constrains producer communities in stream ecosystems.

The current paradigm that stream producers are under exclusive macronutrient control was recently challenged by continental studies, demonstrating that iron supply constrained diatom biodiversity and energy flows. Using algal abundance and water chemistry data from the National Water-Quality Assessment Program, we determined for the first time community thresholds along iron gradients in non-acidic running waters, i.e. 30-79.5 µg L(-1) and 70-120 µg L(-1) in oligotrophic and eutrophic streams, respectively. Given that Fe concentrations fell below both thresholds in 50% of US streams, and below the eutrophic threshold in 75% of US streams, we suggest that Fe limitation is potentially widespread and attribute it to the restricted distribution of wetlands. We also report results from the first laboratory experiments on algal-iron interactions in streams, revealing that iron supplementation leads to significant biovolume and biodiversity increase in both nitrogen fixing and non-nitrogen fixing algae. Therefore, the progressive brownification of freshwaters due to rising dissolved organic carbon and iron levels can have a stimulating influence on microbial producers with cascading effects along the trophic hierarchy. Future research in running waters should focus on the role of iron in algal physiology and biofilm functions, including accumulation of biomass, fixing atmospheric nitrogen and improving water quality.

Bloom of Gymnodinium catenatum in Bahía Santiago and Bahía Manzanillo, Colima, Mexico

Gymnodinium bloom events are of concern, since they produce toxins, which have unfavorable consequences to marine ecosystems, human health and the economy. This report describes the physico-chemical conditions that were present during the algal bloom event on May 2010 in Bahía Manzanillo and Bahía Santiago, Colima, Mexico. For this, seawater nutrient analysis, phytoplankton counts, identification, and toxicity tests were undertaken. Nutrients in seawater were determined using colorimetric techniques, the higher concentrations (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2) were related with upwelling waters that promoted the algal bloom that began after registering the year lowest sea-surface temperature, favoring the rapid growth of G. catenatum (up to 1.02 x10(7)cells/L). Phytoplankton counting was carried out using sedimentation chambers and cells enumerated on appropriated area. The bloom persisted in the bays for approximately two weeks and was associated with toxicity (determined with HPLC) in local oysters (1525.8μg STXeq/100g), and in phytoplankton (10.9pg STXeq/cells) samples. Strong variations in cell toxicity (1.4 to 10.9pg STXeq/cells), most likely reflected the availability of inorganic nutrients. The toxin profile of the phytoplankton samples consisted of 11 toxins and resembled those recorded for several strains of G. catenatum isolated from other coastal areas of Mexico.

La proliferación de Gymnodinium son motivo de preocupación, debido a que en algunas circunstancias producen toxinas, que tienen consecuencias desfavorables para los ecosistemas marinos, la salud humana y la economía. Este trabajo describe las condiciones fisicoquímicas presentes durante una proliferación algal detectado en mayo de 2010 en la Bahía de Santiago y Bahía Manzanillo (Colima, México). La proliferación algal inició poco tiempo después de registrarse las temperaturas oceánicas superficiales más bajas del año, las cuales permitieron un aumento de las concentraciones de nutrientes (8.88μM DIN, 0.78μM PO4 and 24.34μM SiO2) que favorecieron el desarrollo de G. catenatum (hasta 1.02 x10(7)cel/L). Esta proliferación se detectó en las bahías durante dos semanas y fue relacionada con toxicidad en ostiones de la localidad (1525.8μg STXeq/100g) y en muestras de fitoplancton (10.9pg STXeq/cel). Fuertes variaciones en la toxicidad de G. catenatum (1.4 a 10.9pg STXeq/cel) pudieron reflejar la disponibilidad de nutrientes inorgánicos. El perfil de toxinas de las muestras del fitoplancton consistieron en 11 toxinas semejantes a las de varias cepas de G. catenatum aisladas de otras áreas de las costas de México.

Simultaneous determination of microcystin contaminations in various vertebrates (fish, turtle, duck and water bird) from a large eutrophic Chinese lake, Lake Taihu, with toxic Microcystis blooms.

This is the first to conduct simultaneous determination of microcystin (MC) contaminations in multi-groups of vertebrates (fish, turtle, duck and water bird) from Lake Taihu with Microcystis blooms. MCs (-RR, -YR, -LR) in Microcystis scum was 328 microg g(-1) DW. MCs reached 235 microg g(-1) DW in intestinal contents of phytoplanktivorous silver carp, but never exceeded 0.1 microg g(-1) DW in intestinal contents of other animals. The highest MC content in liver of fish was in Carassius auratus (150 ng g(-1) DW), followed by silver carp and Culter ilishaeformis, whereas the lowest was in common carp (3 ng g(-1) DW). In livers of turtle, duck and water bird, MC content ranged from 18 to 30 ng g(-1) DW. High MC level was found in the gonad, egg yolk and egg white of Nycticorax nycticorax and Anas platyrhynchos, suggesting the potential effect of MCs on water bird and duck embryos. High MC contents were identified for the first time in the spleens of N. nycticorax and A. platyrhynchos (6.850 and 9.462 ng g(-1) DW, respectively), indicating a different organotropism of MCs in birds. Lakes with deaths of turtles or water birds in the literatures had a considerably higher MC content in both cyanobacteria and wildlife than Lake Taihu, indicating that toxicity of cyanobacteria may determine accumulation level of MCs and consequently fates of aquatic wildlife.

Phytoplankton biodiversity changes in a shallow tropical reservoir during the hypertrophication process / Mudanças na biodiversidade fitoplanctônica em um reservatório tropical raso durante o processo de hipereutrofização

Study aimed at evaluating phytoplankton biodiversity changes in a shallow tropical reservoir during its hypertrophication process. Samplings were carried out monthly during 8 consecutive years (1997-2004) in 5 depths. Conspicuous limnological changes in the reservoir derived from the presence and/or removal of the water hyacinth, characterized 3 different phases. Over the time series, reservoir changed from a typical polymictic eutrophic system to hypertrophic one, leading to a reduction of approximately 70 species (average 37 percent). Chlorophyceae accounted for the highest species richness (46 percent) among all algal classes and strictly followed total species richness variation. Internal feedback mechanisms intensification over phase III clearly promoted the sharp decrease in biodiversity. Highest decreases, mainly during springs, occurred simultaneously to the highest Cyanobacteria blooms. Increased turbidity due to heavy phytoplankton blooms suppressed all other algal groups, so that at the end of the present study even Cyanobacteria species richness decreased. Total dissolved phosphorous was included in most of the best selected models used to analyze the temporal patterns in species richness loss. Present data show that biodiversity loss following trophic change was not a single dimension of a single factor but, rather, a template of factors (e.g. light, stability) co-varying in consequence of the larger levels of biomass supported in the reservoir.

Estudo avaliou as mudanças na biodiversidade da comunidade fitoplanctônica em um reservatório tropical raso durante processo de hipereutrofização. Foram realizadas amostragens mensais durante oito anos consecutivos (1997-2004) em cinco profundidades. Mudanças limnológicas conspícuas no reservatório foram a conseqüência da presença e/ou remoção do aguapé, caracterizando três fases limnológicas. Durante a série temporal, o reservatório mudou de um sistema eutrófico polimítico típico para um sistema hipereutrófico, levando à redução de aproximadamente 70 espécies (média de 37 por cento). Chlorophyceae foi a classe com a maior riqueza de espécies (46 por cento) entre todas e seguiu, intimamente, a variação da riqueza total de espécies. A intensificação dos mecanismos internos de retroalimentação durante a fase III claramente promoveram uma acentuada queda da biodiversidade. Os decréscimos mais acentuados, especialmente durante as primaveras, ocorreram simultaneamente às maiores florações de Cyanobacteria. O aumento de turbidez provocado pelas florações maciças suprimiu outros grupos de algas de forma que, no final do presente estudo, até mesmo a riqueza de Cyanobacteria decaiu. Fósforo total dissolvido foi incluído na maioria dos melhores modelos selecionados para análise dos padrões temporais da perda da biodiversidade. Os presentes dados mostram que a perda da biodiversidade durante a mudança trófica não esteve relacionada a apenas um fator, mas a um conjunto deles (exemplos: luz, estabilidade), que co-variaram em conseqüência dos elevados níveis de biomassa mantidos pelo reservatório.

The ecological dynamics of Barra Bonita (Tietê River, SP, Brazil) reservoir: implications for its biodiversity / A dinâmica ecológica da represa de Barra Bonita: as implicações na sua biodiversidade

Barra Bonita reservoir is located in the Tietê River Basin - São Paulo state - 22° 29" to 22° 44" S and 48° 10° W and it is the first of a series of six large reservoirs in this river. Built up in 1963 with the aim to produce hydroelectricity this reservoir is utilized for several activities such as fish production, irrigation, navigation, tourism and recreation, besides hydroelectricity production. The seasonal cycle of events in this reservoir is driven by the hydrological features of the basin with consequences on the retention time and on the limnological functions of this artificial ecosystem. The reservoir is polymitic with short periods of stability. Hydrology of the basin, retention time of the reservoir and cold fronts have an impact in the vertical and horizontal structure of the system promoting rapid changes in the planktonic community and in the succession of species. Blooms of Microcystis sp. are common during periods of stability. Superimposed to the climatological and hydrological forcing functions the human activities in the watershed produce considerable impact such as the discharge of untreated wastewater, the high suspended material contributions and fertilizers from the sugar cane plantations. The fish fauna of the reservoir has been changed extent due to the introduction of exotic fish species that exploit the pelagic zone of the reservoir. Changes in the primary productivity of phytoplankton in this reservoir, in the zooplankton community in the diversity and organization of trophic structure are a consequence of eutrophication and its increase during the last 20 years. Control of eutrophication by treating wastewater from urban sources, adequate agricultural practices in order to diminish the suspended particulate matter contribution, revegetation of the watershed and riparian forests along the tributaries are some possible restoration measures. Another action that can be effective is the protection of wetlands...

A represa de Barra Bonita localizada na bacia do médio Tietê, Estado de São Paulo (22° 29" a 22° 44" S e 48° 10" W) é o primeiro de uma série de seis reservatórios de grande porte localizados nesse rio. Construída em 1963, com a finalidade de produção de energia elétrica, esta represa é utilizada atualmente também para produção de peixes, recreação, turismo, navegação e irrigação. O ciclo estacional de eventos nesse reservatório é dirigido, em grande proporção, pelas características hidrológicas da bacia hidrográfica com conseqüências nas funções limnológicas desse ecossistema. O reservatório é polimítico com curtos períodos de estabilidade vertical. A hidrologia da bacia hidrográfica, o tempo de retenção do reservatório e as frentes frias têm um papel fundamental na estrutura horizontal e vertical do sistema, produzindo rápidas alterações na comunidade planctônica e na sucessão de espécies do fitoplâncton, zooplâncton e bacterioplâncton. Florescimentos de Microcystis aeruginosa são freqüentes durante períodos de estabilidade térmica vertical. Atelomixia é também um fenômeno recorrente na represa de Barra Bonita. Os 114 tributários são elementos de heterogeneidade espacial na represa. Superpostas às funções de forças climatológicas e hidrológicas, as atividades humanas na bacia hidrográfica produzem considerável impacto, tais como a descarga de nitrogênio e fósforo de esgotos não tratados, materiais particulados e dissolvidos em suspensão, e fertilizantes provenientes das extensas plantações de cana-de-açúcar na bacia hidrográfica. A fauna iíctica apresentou inúmeras alterações, principalmente, devido à introdução de espécies exóticas de peixes que exploram a zona pelágica do reservatório. Alterações na produção primária do fitoplancton, na comunidade zooplanctônica e no bacterioplâncton, e na estrutura trófica, são uma das conseqüências da eutrofização e do seu aumento nos últimos 20 anos. Além disto, a toxicidade e a predação intrazooplanctônica...

Influence of N, P additions on the transfer of nickel from phytoplankton to copepods.

We examined the influence of macronutrient (nitrate and phosphate) additions on Ni uptake by phytoplankton (Prorocentrum donghaiense and Skeletonema costatum) and its subsequent transfer to marine copepods (Calanus sinicus and Labidocera euchaeta). Ni uptake by phytoplankton after 24h of exposure was markedly dependent on nutrient conditions, with a higher nutrient quota facilitating Ni accumulation in the algae. Trophic transfer was quantified by measurements of the Ni assimilation efficiency in C. sinicus and L. euchaeta, feeding on the algae under different nutrient treatments. Ni assimilation efficiency generally increased with an increase of nutrient concentration in the algae. A significant positive-correlation was found between the Ni assimilation efficiencies of the copepods and the %intracellular Ni in the algal cells. However, ambient nutritional conditions had little effect on the physiological turnover rate constant of Ni by copepods. Thus, nutrient enrichment may lead to an increase in Ni uptake and transfer in marine plankton.

First report of aphantoxins in China--waterblooms of toxigenic Aphanizomenon flos-aquae in Lake Dianchi.

The oligohaline cyanobacterium Aphanizomenon flos-aquae (L.) Ralfs (A. flos-aquae) has been reported in several countries to produce paralytic shellfish poisons (PSPs) or protracted toxic effects. In the past years, A. flos-aquae blooms have occurred annually in the eutrophic Lake Dianchi (300 km(2) in area, located in southwestern China). Material from natural blooms dominated by A. flos-aquae was collected and lyophilized. Acute toxicity testing was performed by mouse bioassay using extracts from the lyophilized material. Clear symptoms of PSPs intoxications were observed. To confirm the production of PSPs, a strain of A. flos-aquae (DC-1) was isolated and maintained in culture. Histopathological effects were studied by examining the organ damages using transmission electron microscopy (TEM). Slight hepatocytic damage with swollen mitochondria was found. The ultrastructural pulmonary lesions were characterized by distortied nuclei and indenting of karyotheca, together with degeneration and tumefaction of mitochondria and endoplasmic reticulum. Control animals injected with acetic acid did not exhibit histopathological damage in any organ. Toxic effects of cultured algal cells on enzymatic systems in the mouse were studied using sublethal doses of extracts. Significant glutathione-S-transferase (GST) and lactate dehydrogenase (LDH) increases, together with decrease of the glutathione (GSH) level, were measured. These results indicated a potential role of PSPs intoxicating and metabolizing in the test animals. HPLC-FLD and LC/MS analysis of extracts from cultured material demonstrated the PSP toxins produced by A. flos-aquae bloom. To the best of our knowledge, this is the first study reporting chemically and toxicologically confirmed PSP toxins related to A. flos-aquae in China.

Las macrófitas de algunos lagos alto-andinos del Ecuador y su bajo potencial como bioindicadores de eutrofización / Macrophytes from some high Andean lakes of Ecuador and their low potential as bioindicators of eutrophication

Se estudió la presencia de macrófitas en tres lagos de altoandinos en Ecuador,Lago San Pablo,Laguna La Mica y Lago Cuicocha.Los primeros dos son eutróficos, mientras que el último es un lago de caldera extremadamente oligotrófico.Las especies dominantes en los lagos eutróficos son:Ceratophyllum demersum , Myriophyllum quitense ,Potamogeton illinoensis ,P. striatus y Elodea matthewsii .En el lago oligotrófico están presentes P.pectinatus,P.illinoensi s,y las Characeae Chara rusbyabana ,Ch.globularis y Nitella acuminata .La máxima profundidad para la presencia de macrófitas puede ser usada como un indicador del estado de eutroficación,la cual va desde 5 m en la Laguna Mica a 35 m en el Lago Cuicocha.El valor de la bioindicación de las especies de macrófitas en estos lagos altoandinos es bajo,debido a que solo unas pocas especies están presentes,y algunas de ellas no son específicas para las condiciones ambientales

The occurrence of macrophyte in three high Andean lakes of Ecuador,Lago San Pablo, Laguna La Mica and Lago Cuicocha was recorded in 5-9 transects per lake.The first two lakes are eutrophic, the third is an extremely oligotrophic caldera lake.The dominant species in eutrophic lakes are Ceratophyllum demersum ,Myriophyllum quitense ,Potamogeton illinoensis ,P.striatus and Elodea matthewsii .In the oligotrophic lake P.pectinatus,P.illinoensi s,and the Characeae Chara rusbyana ,Ch.globularis and Nitella acuminata occur.The maximum depth of the macrophyte ’s presence can be used as an indicator of the trophic state,ranging from about 5 m in Mica to 35 m in Cuicocha.The bioindication value of the macrophyte species in these high Andean lakes is low,because few species occur and because some of them are not specific to environmental conditions

Decoloración en proliferaciones de microalgas como parámetro bioindicador en la Bahía de Mazatlán, México / Discoloration of microalgal blooms as a bioindicating parameter of Bahia de Mazatlan, Mexico

Hace 25 años la UNAM desarrolló un programa de observación y muestreo de mareas rojas en la Bahía de Mazatlán (1979-2003), con el propósito de conocer su evolución a través del tiempo. Se apoyó en observaciones diarias de las decoloraciones (manchas) y los resultados indican cinco tendencias: I) Años sin días de manchas, los cuales están asociados al fenómeno de El Niño; II) Años de días con manchas súbitas; III) Años con un número similar de días de manchas; IV) Años con una disminución progresiva de los días de manchas; V) Años con un aumento gradual de manchas. El promedio anual es de 25.3 días de decoloraciones. En el año 2000 hubo 96 días de decoloraciones y representa el más alto en los 25 años de registros. En marzo es donde existen mas frecuentemente las manchas de mareas rojas (174 días) incluyendo las tóxicas. Estas tendencias nos indican un comportamiento continuo de la máxima concentración de las microalgas y por lo tanto desempeñan un papel muy importante para conocer el deterioro ambiental que sufren las zonas costeras por aumento de microalgas nocivas y tóxicas

In order to verify whether harmful algal blooms increased since 1979, a long-term project for the study of harmful algal blooms in Mazatlán Bay began 25 years ago (1979-2003). Observations were done daily and results indicate five trend types: I) years without discoloration related to El Niño events; II) years with days of sudden occurrence of discoloration, related to the release of accumulated energy after El Niño events; III) years with similar number of discoloration events (days); IV) years with a progressive decrease of the occurrence (days) of discoloration events; V) years with gradual increase of discoloration events. The annual mean average of discoloration is of 25.3 days. Ninety-six discoloration events were recorded during year 2000, and represent the highest number of events in the last 25 years. Discoloration events are more common in March (174 days), harmful and toxic blooms included. This indicates continuity in the occurrence of the highest content of microalgae, and therefore, it is concluded that they play an important role for a better understanding of the environmental deterioration undergone by the coastal zone due to an increase of harmful and toxic microalgae blooms

Blooms of Cochlodinium polykrikoides (Gymnodiniaceae) in the Gulf of California, Mexico

Cochlodinium polykrikoides was the species responsible for the discoloration that occurred between September 15th and 27th , 2000 in a shallow coastal lagoon located in the southern part of the Bahía de La Paz, on the west side of the Gulf of California. Blooms of C. polykrikoides were observed four days after two rainy days with a seawater temperature of 29 to 31°C. Nutrient concentration ranges during the bloom were 0.165- 0.897 µM NO2 +NO3 , 0.16-3.25 µM PO4 , and 1.0-35.36 µM SiO4 . Abundance of C. polykrikoides ranged from 360 x 103 to 7.05 x 106 /cells l-1 . Biomass expressed in terms of chlorophyll a was high, ranging from 2.7 to 56.8 mg/m3 . A typical dinoflagellate pigment profile (chlorophyll a and c, peridinin, diadinoxantin, and b -carotene) was recorded. In this study, the red tide occurred in front of several fish and shrimp-culture ponds. No PST toxins were found in the samples. However, 180 fish were found dead in the infected fish-pond; the gills were the most affected part. C. polykrikoides is a cyst-forming species that recurs in this area. New blooms were observed in November 2000 and September-November 2001 in the same area. Anthropogenic activities, such as eutrophication caused by water discharge in this shallow lagoon, and nutrient enrichment in the culture ponds, as well as effects from precipitation and wind stress, could have favored the outbreak of this dinoflagellate

Durante el desarrollo de una marea roja ocurrida del 15 al 27 de septiembre del año 2000 en la Ensenada de La Paz, B.C.S. se tomaron muestras de agua con una botella Van Dorn para determinar la temperatura, la especie causante y la cantidad de nutrientes y pigmentos fotosintéticos. Se hicieron análisis de toxinas de Cochlodinium polykrikoides, la especie responsable de esta marea roja. La mayoría de los especimenes formaron cadenas de cuatro células y raramente de dos. La abundancia fue de 360 x 103 a 7.05 x 106 /cels l-1 . Los florecimientos de C. polykrikoides ocurrieron cuatro días después de dos días lluviosos; el intervalo de temperatura fue de 29 a 31°C. La concentración de nutrientes registrada durante este fenómeno fue 0.165-0.897 µM NO2 +NO3 , 0.16-3.25 µM PO4 , y 1.0-35.36 µM SiO4 . El perfil pigmentario reveló la presencia de clorofila a y c, peridinina, diadinoxantina, y b -caroteno. La biomasa total expresada en clorofila a fue alta, oscilando entre 2.7 y 56.8 mg/m3 , mientras que la biomasa de Cochlodinium, expresada en peridinina, varió entre 0.68 y 32.03 mg/m3 . En este estudio, la marea roja se desarrolló cerca de varios estanques de cultivo de peces y camarón. En uno de ellos proliferó C. polykrikoides. Los análisis de toxinas PST fueron negativos; sin embargo, durante el incremento de las proliferaciones algunos estanques fueron alcanzados y murieron 180 peces, principalmente pargos (Lutjanus argentiventis, Pomadasys macracantus). Las branquias fueron las partes más afectadas. En condiciones desfavorables C. polykrikoides forma quistes, lo cual ha provocado su recurrente proliferación en el área, registrándose nuevas proliferaciones en noviembre del 2000 y en septiembre-noviembre del 2001. Actividades antropogénicas como la eutroficación causada por la descarga de aguas residuales y de nutrientes de los estanques de cultivo, pudieran estar favoreciendo la proliferación de este dinoflagelado

Proliferaciones de Pseudo-nitzschia spp. (Bacillariophyceae) y otras especies del microplancton en la Bahía de Mazatlán, México / Blooms of Pseudo-nitzschia spp. (Bacillariophyceae) and other phytoplankton species at Bahia de Mazatlan, Mexico

Observaciones previas sobre el microplancton de la Bahía de Mazatlán, en el otoño de 1996, revelaron la existencia de altas densidades de Pseudo-nitzschia spp. Este mismo fenómeno se encontró en noviembre 1998 y un mes después se había desplazado al sur de la Bahía de Mazatlán, mientras que por esas mismas fechas, en California, EUA, se registraban accidentes de envenenamiento de mamíferos marinos, accidentes que en el noroeste de México se aprecian entre enero y marzo. Mensualmente se recolectaron muestras de agua superficial (< 0.5 m) y subsuperficial (10 m), de noviembre 1998 a enero 1999 y cada semana, entre febrero 1999 y mayo 2000; las muestras fueron analizadas por la técnica de Utermöhl a 400X. La cuantificación del microplancton presentó un amplio pulso invernal y otro menor en verano de cada ciclo anual. Con el empleo de microscopio electrónico (MEB y MET), se reconocieron cuatro especies de Pseudo-nitzschia y una más en estudio reciente. Las densidades de Pseudo-nitzschia fueron, en orden de importancia: 760 céls ml-1 (7 dic.1999), 610 (6 dic.1998), 335 (12 jul.1999), 198 (1º. feb. 1999), 170 (6 nov.1998), 123 (17 mar.1999), 108 (11 ago.1999). Otras especies de diatomeas (Thalassiosira spp., Asterionellopsis glacialis, Chaetoceros spp., Skeletonema costatum), dinoflagelados (Prorocentrum spp., Scripsiella trochoideda) y ciliados (Myrionecta rubra), manifestaron proliferaciones altas durante el período de este estudio

Observations on microplankton in the autumn of 1996 revealed the existence of high densities of Pseudo-nitzschia spp. A similar phenomenon was found in November 1998 and November 1999 and a month later it shifted to the southern Mazatlán Bay while in California, USA, incidents of the poisoning of sea mammals were being recorded; this also happened on the Mexican Pacific coasts from January to March. Water samples collected at surface (<0.5 m deep) and subsurface (10 m deep) monthly, from November 1998 to January 1999 and every week from February 1999 to May 2000, were analyzed by the Utermöhl technique at 400 enlargements. Phytoplankton quantification showed winter and summer pulses; the 1998-1999 period was higher than the 1999-2000 period. Five species of Pseudo-nitzschia were identified by electron microscopy (TEM and SEM); a new study has revealed other species. High values of Pseudo-nitzschia were observed: 730 P-n/ml (Dec. 1999), 610 P-n/ml (Dec. 1998), 335 P-n/ml (Jul. 1999), 198 P-n/ml (Feb. 1999), 170 P-n/ml (Nov. 1998), 123 P-n/ml (Mar. 1999), 108 P-n/ml (Aug. 1999). The blooms of other species of diatoms (Thalassiosira spp., Asterionellopsis glacialis, Chaetoceros spp., Skeletonema costatum), dinoflagellates (Prorocentrum spp., Scripsiella trochoidea) and ciliates (Myrionecta rubra) were also observed

Paralytic Shellfish Poisoning (PSP) in Margarita Island, Venezuela

A severe outbreak of Paralytic Shellfish Poisoning (PSP) occurred in Manzanillo and Guayacán, northwestern coast of Margarita Island, Venezuela, between August and October 1991. A bloom of dinoflagellates including Prorocentrum gracile, Gymnodinium catenatum and Alexandrium tamarense seemed to be responsible for this outbreak. Levels of PSP toxins in mussels (Perna perna) exceeded the international safety limit of saxitoxin, 80 µg STX/100 g meat. PSP toxin values varied between 2 548 and 115 µg STX/100 g meat in Manzanillo, and between 1 422 and 86 µg STX/100 g meat in Guayacán. At both locations, the highest levels were detected in August, when 24 patients exhibited typical symptoms of PSP toxicity after consuming cooked mussels (16 required hospitalization). A high pressure liquid chromatographic (HPLC) procedure was recently used on the 1991 samples. The major toxin detected in samples of both locations was decarbamoyl saxitoxin (dcSTX), but low concentrations of saxitoxin were also found in Manzanillo samples. Gonyautoxins GTX1, GTX2 and GTX3 were detected only at Guayacán, while in both locations, decarbamoylgonyatouxin (dcGTX2,3) toxins were detected. These findings represent the first time that causative toxins of PSP in Venezuela have been chemically identified, and confirm the presence of dcSTX and dcGTX in mussels from the Caribbean Sea. The presence of dcSTX and dcGTX in shellfish is indicative that Gymnodinium catenatum was a causative organism for outbreak of PSP

Un severo brote de intoxicación paralizante por moluscos (PSP en inglés) ocurrió en Manzanillo y Guayacán en la costa noroeste de la Isla de Margarita, Venezuela entre agosto y octubre de 1991. Una proliferación de Prorocentrum gracile, Gymnodinium catenatum y Alexandrium tamarense causó el brote. Los niveles de PSP en mejillón (Perna perna) superaron los niveles máximos permisibles de saxitoxina, 80 µg STX/100g carne. Los niveles de toxinas variaron entre 2 548 y 115 µg STX/100 g carne en Manzanillo y entre 1 422 y 86 µg STX/100g carne en Guayacán. En ambas localidades, los máximos niveles se detectaron en agosto, cuando 24 personas presentaron síntomas típicos de PSP después de consumir mejillones cocidos (16 fueron hospitalizados). Se aplicó recientemente cromatografía líquida de alta presión (HPLC) a muestras del año 1991 y la toxina más detectada fue decarbamoyl saxitoxina (dcSTX), pero también se encontró saxitoxinas en muestras de Manzanillo. Las gonyautoxinas GTX1, GTX2 y GTX3 solo se encontraron en Guayacán; en ambas localidades se detectó decarbamoylgonyatouxin (dcGTX2,3). Estos hallazgos representan la primera vez que las toxinas causantes de un brote de PSP en Venezuela han sido químicamente identificadas, confirmando la presencia de dcSTX y dcGTX en mejillones del mar Caribe. La presencia de dcSTX y dcGTX en moluscos, indica que G. catenatum fue el organismo responsable de la intoxicación

Presencia de los dinoflagelados Ceratium dens, C. fusus y C. furca (Gonyaulacales: Ceratiaceae) en el Golfo de Nicoya, Costa Rica / Presence of the dinoflagellates Ceratium dens, C. fusus and C. furca (Gonyaulacales: Ceratiaceae) in Golfo de Nicoya, Costa Rica

Las proliferaciones algales nocivas (PAN) son un fenómeno frecuente en el Golfo de Nicoya. La morfología y fisiología de estas microalgas son muy importantes debido al hecho de que las especies involucradas en estos eventos presentan características adaptativas. PAN producidas por dinoflagelados del género Ceratium son comunes en algunas partes del mundo, sin embargo, a pesar del hecho de que la producción de altas concentraciones de toxinas paralíticas sólo se ha documentado a nivel experimental, éste género ha sido asociado con la mortalidad de organismos acuáticos y con la disminución en la calidad del agua, así como el responsable de la mortalidad de ostras y larvas de gambas. Algunas especies del género Ceratium han sido asociados con eventos de mortalidad en peces. Durante un reciente fenómeno PAN que ocurrió cerca de la Isla Tortuga en el Golfo de Nicoya, los pescadores en el área informaron muertes masivas de peces enjaulados. Se tomaron muestras de una PAN que producía una discoloración anaranjada en el agua y tenía un olor fétido. Estas muestras fueron procesadas para observar el detalle ultraestructural usando el microscopio electrónico. En muestras tomadas en superficie, los dinoflagelados observados fueron Ceratium furca, C. fusus y C. dens. El conteo celular reveló cuatro millones de células de este género por litro. Los cambios morfológicos de estas especies son muy variables; por consiguiente la microscopía electrónica es una herramienta muy útil en el estudio ultraestructural de estos organismos. Esta es la primera vez que tres especies del género Ceratium se conocen como productoras concurrentes de PAN en Costa Rica

Harmful Algae Blooms (HAB) are a frequent phenomenon in the Gulf of Nicoya, Costa Rica, as in other parts of the world. The morphology and physiology of these microalgae are important because HAB species have adaptive characteristics. The production of high concentrations of paralytic toxins by Ceratium dinoflagellates has only been documented at the experimental level. However, this genus has been associated with the mortality of aquatic organisms, including oyster and shrimp larva, and fish, and with decreased water quality. Recently, fishermen reported massive mortality of encaged fish near Tortuga Island (Gulf of Nicoya). Samples were taken from an algal bloom that had produced an orange coloration and had a strong foul-smelling odor. Ultrastructural details were examined with scanning electron microscopy. The dinoflagellates Ceratium dens, C. furca and C. fusus were found in samples taken at the surface. The cell count revealed four million cells of this genus per liter. The morphological variability of these species is high; therefore electron microscopy is an useful tool in the ultrastructural study of these organisms. This is the first time that three Ceratium species are reported concurrently producing harmful blooms in Costa Rica