High flow events often comprise the majority of annual discharge and riverine geochemical flux of phosphorus (P) and metals such as iron (Fe) and manganese (Mn) due to glacial melt, snowmelt, and storm-driven sustained high flow. Aquatic ecosystem productivity in receiving water bodies such as Lake Champlain and the Gulf of Alaska (GoA) are impacted by the riverine import of nutrients. The magnitude of these high flow events can be a strong predictor of receiving water body conditions, and in some cases can contribute to eutrophication. We explore the intersection of high flow events and land cover in contrasting catchments in Vermont and Alaska, covering a range of land covers including glacial, boreal-forested, mixed hardwood-conifer forested, and agricultural. In Vermont, we explore the hypothesis that riverine dissolved and suspended sediment P loads during spring runoff have a particularly high proportion of reactive species due to unique hydrologic pathways and the association of P with Fe. We compared spring runoff and summer storm concentrations and distribution of dissolved P (DP), dissolved and colloidal metals, and redox sensitive suspended sediment P (RSP). Agricultural catchments in Vermont were characterized by enrichment in RSP and DP during both spring runoff and summer storms, particularly at the onset of snowmelt. In 2014, 82% of the annual DP and 74% of annual RSP loads were delivered to Missisquoi Bay during spring runoff, with the majority of suspended sediment significantly more redox sensitive, and carrying potentially bioavailable P, than typical inputs to limnological models, suggesting that the reactivity of this load is systematically underestimated. In Alaska, we investigate Fe size partitioning and flux throughout the hydrologic year, with additional high-resolution sampling during discrete storm events in adjacent forested and glacierized catchments typical of coastal Alaska. There are clear differences between these catchments during individual storm events, and across seasons, reflecting widely varying source environments for Fe. The geochemical character of river water exported from the forested catchment, dominated by dissolved Fe and DOC, reflects the influence of peatlands and organic-rich soil as the dominant source of Fe and P, while the glacial catchment exports significantly more material derived from glacial weathering of bedrock, reflected in higher sediment and colloidal concentrations. Phosphorus concentrations in both watersheds are very low throughout the year, but significantly higher in the forested catchment, driven by organic matter decomposition. Both Vermont and Alaska are likely to be significantly impacted by climate change, with an increase in the frequency of heavy precipitation events, and continued glacial recession in Alaska driven by rising temperatures. Changes in the timing, provenance, and severity of high flow associated with climate and land cover change will have dramatic impacts on total riverine P and Fe loads, and their potential reactivity and bioavailability in receiving water bodies. Development of conceptual models that incorporate the intersection between high flow events (hot moments) and land cover source environments (hot spots) is critical to understanding how these systems are likely to change in the future.

With the global rise in frequency of harmful algal blooms in estuarine environments comes an increase in prevalence of toxic metabolites, such as microcystin (MC), that some of the cyanobacteria involved will produce. At high concentrations, MC may accumulate in consumer tissues and have deleterious effects on organisms; however impacts of the toxin on aquatic living resources at ecologically relevant concentrations have not been widely documented. We analyzed the effects of MC on juveniles of five fish species from the James River, Virginia to determine if MC has the potential to impede growth. Using three separate experimental approaches, it was shown that exposure to concentrations of the toxin currently observed in the James River estuary do not appear to significantly impact the growth or survivorship of tested fish species. Extraneous factors in parts of the study led to an inability to draw clear conclusions on mortality or growth impacts; however it is evident from the experiments that at least some of the fish species have biological mechanisms in place that allow them to effectively eliminate the toxin from their systems. An ability to extricate the toxin suggests the possibility for fishes to withstand MC exposures and sustain few negative health impacts at low MC concentrations.

Aquatic bacteria respond to changing environmental conditions through a variety of mechanisms including changes in abundance, shifts in community composition and variable activity states. In the tidal-freshwater James River, variation in bacterial abundance was linked to nutrient availability and autochthonous production with highest bacterial densities associated with low-nutrient, high-chlorophyll a conditions. Laboratory experiments revealed that bacterial growth rates were nutrient limited at the low-nutrient site, while co-limitation (nutrients, glucose, light) was apparent at the high nutrient site. Despite large differences in abundance, community composition was similar based on TRFLP and 16S rDNA pyrosequencing. Community similarity was lower among rRNA libraries suggesting that variable activity states are prevalent in natural communities. Rare taxa were more likely to be metabolically active and were capable of dramatic growth under microcosm conditions.

Master of Science / Department of Agronomy / Nathan O. Nelson / Phosphorus (P), an essential nutrient for plant growth and animal needs, has been identified as an ubiquitous water quality impairment in the United States. In Kansas, a major agricultural state, P loading to the surface waters is a top priority because of the critical role of P enrichment in eutrophication processes and resultant water quality degradation. The objective of this study was to quantify the P sorption and desorption of both stream sediments and upland soils in two Kansas watersheds with contrasting degrees of animal agriculture; Upper West Emma Creek (UWEC) and Red Rock Creek (RRC) watersheds. In-stream sediments were collected from banks, pools, riffles and depositional features. Soils were sampled from wheat, row crop, pasture, and manure-amended fields. Stream water samples were taken under baseflow and storm flow conditions. Our analyses of sediments and soils included equilibrium P concentration at zero net P sorption (EPC[subscript]0), maximum adsorption capacity (P[subscript]max), anion exchange extractable P (P[subscript]lab) and degree of P saturation (DPS). Water samples were analyzed for dissolved reactive phosphorous (DRP). Bank erosion pins were installed in order to estimate bank erosion rates in both watersheds. Results showed that in-stream sediments do not have much more sorption capacity remaining indicated by low P[subscript]max and high DPS. A comparison between mean P[subscript]lab of stream sediments (8.8 mg P kg[superscript]-1 soil) versus field soils (61.2 mg P kg[superscript]-1 soil) reflected that they represent a relatively minor long-term P supply. Of the stream sediments, bank soils had the highest Plab concentrations (24.8 mg P kg[superscript]-1 soil) and would be the largest in-stream P source. Manure-amended fields had the highest Plab (118.6 mg P kg[superscript]-1 soil) due to continued inputs of manure-based P; therefore, representing a large available P pool. Bank erosion contributed about 41% and 11% of the total sediment load in UWEC and RRC respectively. Sediments loads indicated that RRC has more upland sediment inputs than UWEC. Moreover, DRP during storm flow was higher at RRC than UWEC, indicating higher P inputs in RRC from upland soils. Finally, in order to minimize P inputs to the stream system, bank stabilization should be addressed in UWEC and upland best management practices should be implemented in RRC.

Seagrass meadows may play a substantial role in climate change mitigation as they are capable to sequester and store substantial amounts of anthropogenic carbon in plant biomass and, more importantly, in their underlying sediments. In this PhD thesis, the carbon-burial potential was assessed by quantifying the amount of organic carbon stored in different seagrass meadows, each dominated by one of the four major seagrass species in the Western Indian Ocean region. Impacts of anthropogenic disturbances on biomass carbon allocation, greenhouse gas emission (methane and nitrous oxide) and production of sulphide were investigated in Chwaka Bay, Zanzibar. The findings showed that east African seagrass meadows generally have high carbon sink capacity. The storage of sedimentary organic carbon, however, varied among seagrass habitats and across sites, and was up to five-fold higher in seagrass sediment to those of nearby unvegetated sediments. Seagrass meadows in eutrophicated sites had higher sedimentary organic carbon content, and substantially higher emission rates of nitrous oxides and methane, compared to more pristine meadows. Disturbances in terms of shading and simulated grazing of seagrass affected several processes, with major decreases in seagrass primary productivity, net community production and biomass carbon, in turn influencing seagrass carbon sequestration as well as stimulating anaerobic microbial processes. In addition, production of sulphide in the sediment and methane emissions from the sediment surface increased significantly when disturbed. At present, seagrass meadows in the Western Indian Ocean have high carbon sink capacity. This important ecosystem service is, however, highly threatened due to regional anthropogenic pressure, which may change the role of blue carbon rich habitats, such as seagrass meadows, from being a sink to a source of greenhouse gases. / <p>At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 1: Manuscript. Paper 2: Manuscript. Paper 4: Manuscript. Paper 5: Manuscript.</p>

Diploma thesis is focused on data evaluation of economic efficiency of provisions for impoving of water quality in Macha's lake. Data estimation of economic value of chase in water quality in Macha's lake were acquired during on-site research in the area. Choice Experiment was used for modelling of recreational demand. The base of Choice Experiment is coming out from Lancaster's Attribution theory and Random utility function. Data presentation and its acquiring is a part of the diploma thesis, there is also discussed the new findings and the base of neoclassical methodology of Cost-Benefit Analysis that is suitable for judging of economic efficiency of provisions that help improving water quality in The Macha's lake. Macha's lake is a signifiant recreational area. While deciding about long term solution of the problem of water quality it is necessary to judge efficiency of invested ressources. Estimations of changes in water quality in Macha's lake is going to be used for Cost-Benefit Analysis. Cost-Benefit Analysis is based on measuring costs and benefits and their comparisons and this Analysis is main scope of the thesis.

Intensifiering av jordbruket globalt har lett till förhöjda halter reaktivt kväve (Nr) i omlopp på jorden. Användningen av stora mängder av framförallt handelsgödselkväve har rubbat balansen mellan reaktivt kväve och icke reaktivt kväve i kvävecykeln, vilket orsakar stora problem i form av övergödning. För att motverka denna negativa miljöpåverkan är det viktigt att uppmärksamma både makthavare och konsumenter på problemen och redovisa vilken påverkan som sker vid produktion av olika livsmedel. Detta så att konsumenter har möjlighet göra hållbara val vid köp av livsmedel och så att ett hållbart jordbruk kan utvecklas. För att beräkna ett livsmedels påverkan på kvävecykel kan flera olika metoder användas. I denna studie analyseras indikatorerna kväveffektivitet (NUE), kvävefotavtryck samt övergödningspotential för att undersöka vilken av indikatorerna som lämpar sig bäst för konsumentvägledning. NUE definieras som Nut/Nin och beräknar hur stor andel av inflödet av N som kommer ut i slutprodukten. Kvävefotavtrycket beräknas som (Nin-Nut) per kg produkt och övergödningspotential som utsläpp av olika övergödande ämnen per kg produkt. Indikatorerna applicerades på olika svenska livsmedel samt sojabönor från Brasilien och resultatet visade på att högst övergödningspotential och kvävefotavtryck fås för kött från kyckling, gris och nötkreatur. För samma indikatorer beräknades lägst potential och fotavtryck för gurka, tomat och morot. NUE beräknades vara högst för gurka på 0,90 och lägst för hallon och jordgubbe på 0,05 samt 0,08. Vid jämförelse av indikatorerna fastställdes att kvävefotavtrycket är bäst lämpad för konsumentvägledning eftersom resultatet är lättförståeligt och det kan kopplas till specifika miljöproblem så som övergödning. Övergödningspotentialen är också en lättförståelig indikator men N som resurs analyseras inte. Indikatorn kräver också mycket data som kan vara svår att få tag på för produkter som produceras i andra länder. Resultatet av NUE är lite mer komplicerat och indikatorn kan passa bättre som ett mått på hur kväveeffektivt en gård eller land är och därav lämpar sig indikatorn bättre för bönder och makthavare än konsumenter. / The amount of reactive nitrogen in the environment has increased as food production has intensified. A disrupted balance between reactive and non-reactive nitrogen can lead to a destabilisation of the state that the earth system is currently in. In order to create a sustainable agriculture, it is important to inform politicians and consumers about the impact on the nitrogen cycle associated with different food products in order to enable sustainable food choices. The objective of this study was to find an indicator that present the effect on the nitrogen cycle in food production and can be used for consumer guidance. The indicators evaluated in this study were Nitrogen Use Efficiency (NUE), the nitrogen footprint and eutrophication potential. NUE is calculated by dividing Nout by Nin. The nitrogen footprint is defined as the amount of reactive nitrogen released to the environment per product unit and is calculated as (Nin-Nout) per kg product. The indicator eutrophication potential calculates the amount of substances that can lead to eutrophication and is expressed per kg product. The results show that chicken, pig and beef have the highest eutrophication potential as well as nitrogen footprint. The lowest eutrophication potential and nitrogen footprint was found for cucumber, tomato and carrot. The highest NUE was calculated for cucumber with a value of 0,90 and the lowest was found for raspberries (0,05) and strawberries (0,08). The indicator that is recommended for consumer guidance after analysis is the nitrogen footprint because it is easy to understand, and the result can connect to specific problems such as eutrophication. The eutrophication potential is also easy to understand, however the use of nitrogen as a resource is not considered and it could be a problem to find data for products produced in other countries. The result from NUE is a bit more complicated for consumers to understand and the indicator might be more useful for politicians and farmers than for consumer guidance.

La prise de conscience des risques liés à la dégradation de la qualité des milieux lagunaires vis-à-vis de l’eutrophisation a abouti à la mise en œuvre d’actions de gestion visant à réduire les apports en nutriments. Certaines lagunes sont aujourd’hui en phase de restauration, avec une amélioration notable de la qualité de l’eau liée notamment à la réduction des biomasses phytoplanctoniques. En revanche, la réponse des macrophytes benthiques semble plus complexe et non linéaire. A travers une approche complémentaire basée sur l’analyse statistique des données d’observations acquises de 1998 à 2015 et sur des mesures in situ, cette thèse vise à identifier la dynamique temporelle et spatiale des macrophytes ainsi que leur rôle fonctionnel au cours du processus d'oligotrophisation. Au sein des lagunes méditerranéennes, la salinité et les teneurs en nutriments dans la colonne d'eau sont les principaux paramètres qui structurent la distribution des macrophytes benthiques. L’analyse statistique menée sur 21 lagunes polyhalines et euhalines a permis d'illustrer les premières étapes de restauration. La réduction des apports externes a conduit à un basculement rapide (3-4 ans) d’un système totalement dominé par le phytoplancton vers un système dominé par les macroalgues opportunistes et notamment les ulves. La réduction de la disponibilité en azote dans la colonne d'eau liée au développement des ulves favoriserait le développement des gracilaires (algue rouge) et des chaetomorphes (algue verte filamenteuse). Bien plus que la seule conséquence de la restauration, la présence d'espèces clés jouerait ainsi un rôle central dans la restauration en régulant les flux d'azote et de phosphore au sein du système et en créant les conditions favorables à l'apparition d'autres espèces plus pérennes. Bien que notre théorie décrive une tendance vers le retour des macrophytes pérennes pour les trajectoires de re-oligotrophisation, nous n’avons pas encore pu documenter ce retour dans les lagunes après une longue période d’absence. Ceci, montre l’importance de prendre en compte, entre autres, l’importance des sources internes d’éléments nutritifs et de la connectivité pour la recolonisation des angiospermes dans les lagunes. / The growing awareness of the negative impacts of the degradation of the water quality in coastal lagoons because of eutrophication has resulted in public action aiming at the reduction of the nutrient loadings into these lagoons. Hence, some of these coastal lagoons are currently undergoing ecological restoration and have shown a clear improvement of their water quality linked to decreasing phytoplankton biomass in the last 10 years. However, the response of the benthic macrophytes appears more complex, particularly by showing non-linear behaviour. By using complementary approaches including statistical analyses of long-term observations (1998-2015) and in situ measurements, this thesis aims to describe the dynamics of the macrophytes in space and time and to study their functional role during the oligotrophication process. Salinity, depth and nutrient concentrations in the water column represent the main factors that statistically explain the distribution of the benthic macrophyte communities in Mediterranean coastal lagoons. The first steps of the ecological restoration in eutrophied polyhaline and euhaline lagoons has been inferred from the statistical analysis of time series in 21 coastal lagoons. The reduction of the external nutrient loading results in a rapid regime shift (3-4 years) from a phytoplankton-dominated system to a macroalgae-dominated system, with particularly Ulva species. The decreasing inorganic nitrogen concentrations due to uptake by Ulva spp. in the water column appears to facilitate the development of Gracillaria spp. (red algae) and Chaetomorpha spp. (green filamentous algae). While the appearance of these macroalgal species is the result of the ecological restoration, these species also play a central role in this process by regulating the biogeochemical element fluxes. This way these species create more favourable conditions for perennial species. Although for re-oligotrophication trajectories in coastal lagoons our theory describes a tendency towards the return of perennial species, so far, we have not been able to document their return after a long period of absence. This shows, that among other factors, the internal nutrient loading and ecological connectivity are important factors to take into account for the recolonization of angiosperms in coastal lagoons.

A represa do Lobo (Broa) é um ecossistema bastante estudado, entretanto, nos últimos anos foram observadas várias alterações nas suas condições, devido, principalmente, ao processo de eutrofização. Para o maior entendimento dos processos que ocorrem nos sistemas aquáticos, a análise integrada do ecossistema em termos de bacia hidrográfica é de suma importância. Além disso, as comunidades biológicas, com destaque o zooplâncton, representam as respostas estruturais e funcionais do sistema. Dessa forma, o objetivo do trabalho foi analisar a distribuição da comunidade zooplanctônica frente à heterogeneidade ambiental, de sistemas lóticos e lêntico e dos impactos na área de entorno da bacia hidrográfica do Lobo. Para tanto, foram realizadas coletas em quatro períodos (chuvoso, seco e intermediários) em 17 pontos de coleta distribuídos no reservatório e nos tributários. Foram avaliadas as variáveis físicas e químicas da água (temperatura, pH, oxigênio dissolvido, condutividade, transparência da água, nutrientes, material em suspensão e metais), variáveis climatológicas (temperatura do ar, precipitação e velocidade do vento) e variável biológica (clorofila a). Para a comunidade zooplanctônica foi determinada a composição, densidade e abundância, bem como índices biológicos. De acordo com os resultados, a represa do Lobo apresentou, de uma forma geral, homogeneidade espacial nas variáveis analisadas, apresentando condições eutróficas em todos os pontos. A comunidade zooplanctônica, representada por 64 espécies, também indicou a degradação da represa, como por exemplo, o aumento da representatividade do gênero Brachionus, o desaparecimento de Bosmina coregoni e o aparecimento de Moina micrura. Por sua vez, os tributários apresentaram heterogeneidade ambiental em muitas variáveis, com o ponto AB/L2, com condições características de ambientes mais poluídos, e o ponto JG, com altas concentrações de clorofila a. A comunidade zooplanctônica foi representada por 93 espécies, com a maior constância de espécies que possuem lórica (Kellicottia bostoniensis, Keratella tropica, Platyas quadricornis, Lecane bulla e Lecane lunaris) e da família Chydoridae. A heterogeneidade temporal foi mais marcada que a espacial, com o agrupamento dos meses de maior precipitação (janeiro e outubro) com maiores graus de trofia e maiores concentrações de formas fosfatadas. / The Lobo reservoir (Broa) is a well-studied ecosystem, however, in recent years have passed through several changes in its conditions, mainly, due to the process of eutrophication. For better understanding the processes occurring in aquatic systems, the integrated analysis of the ecosystem in terms of watershed is of utmost importance. In addition, the biological communities, especially zooplankton, represent the structural and functional responses of the system. Thus, the objective was to analyze the distribution of zooplankton front of environmental heterogeneity in lotic and lentic systems and impacts in the area surrounding the basin of the Lobo. For this purpose, samples were collected in four periods (rainy, dry and intermediates) in 17 sampling stations distributed in the reservoir and tributaries. We evaluated the physical and chemical variables of water (temperature, pH, dissolved oxygen, conductivity, water transparency, nutrients, suspended solids and metals), climatic variables (air temperature, precipitation and wind speed) and the biological variable (chlorophyll a). For the zooplankton community was determined the composition, density and abundance, and biological indices. According to the results, the Lobo reservoir showed, in general, spatial homogeneity in the variables analyzed, with eutrophic conditions at all points. The zooplankton community, represented by 64 species, also indicated the degradation of the dam, such as, the increased representation of the genus Brachionus, the disappearance of Bosmina coregoni and the appearance of Moina micrura. On the other hand, the tributaries are heterogeneous in many environmental variables, with the station AB/L2 with conditions characteristic of more polluted environments, and JG station, with high concentrations of chlorophyll a. The zooplankton community was represented by 93 species, with the greater constancy of loricate species (Kellicottia bostoniensis, Keratella tropica, Platyas quadricornis, Lecane bulla and Lecane lunaris) and the family Chydoridae. The temporal heterogeneity was more marked than the spacial heterogeneity, with the grouping of the months of highest rainfall (January and October) with greater degrees of trophy and higher concentrations of phosphorylated forms.

Foram levantados dados referentes a Rede de Monitoramento da Qualidade das Águas Superficiais do Estado de São Paulo, da CETESB (Companhia de Tecnologia de Saneamento Ambiental da Secretaria de Estado de Meio Ambiente do Estado de São Paulo, Brasil ), do período de 1996 a 2001, totalizando 69 pontos de amostragem, (35 em rios e 34 em reservatórios). As variáveis examinadas foram clorofila a, nutrientes e variáveis complementares utilizadas na avaliação do grau de trofia desses ambientes através do Índice de Estado Trófico de Carlson, modificado por Toledo (1983). Os pontos de amostragem em ambientes lóticos apresentaram maiores valores de fósforo total, e os em ambientes lênticos apresentaram maiores valores de clorofila a, DBO e nitrogênio amoniacal. Não houve diferença significativa entre os valores de fósforo total ou de nitrogênio total entre a estação seca e chuvosa.. Em ambos os tipos de ambientes o nutriente limitante foi o fósforo. A clorofila a, corrigida para feofitina a, foi adotada como indicadora da biomassa fitoplanctonica, tanto para reservatórios como para rios, sendo que a relação clorofila a:feofitina a foi de 2:1 em reservatórios e de 1:1 em rios. Os valores médios de clorofila a, calculados através de média geométrica, podem ser utilizados para indicar o grau de eutrofização, bem como a probabilidade de ocorrência de valores máximos. As regressões obtidas entre clorofila a e fósforo total, para rios e reservatórios, foram consideradas distintas, sendo que ambas apresentaram alta correlação. O modelo proposto para a previsão da clorofila a, através das concentrações de fósforo total, em reservatórios, integra os dados do estudo do CEPIS (Centro Panamericano de Ingenería Sanitária y Ciencias del Ambiente), sendo que a introdução do tempo de residência melhora, significativamente, o referido modelo. Foram estimados os valores basais de fósforo total, ortofosfato solúvel, nitrogênio total e de clorofila a, além de transparência para reservatórios e de turbidez para rios, os quais foram considerados valores limites entre a classe oligotrófica e a mesotrófica. Foram propostas ainda novas classificações de trofia, bem como novos índices de estado trófico, distintos para ambientes lóticos e lênticos, nos quais foi introduzida uma nova classe, entre as classes eutrófica e a hipereutrófica, denominada supereutrófica. Estes novos índices foram testados com os dados de 2001, 2002 e 2003 e apresentaram maior sensibilidade e maior coerência entre os índices calculados através das concentrações de clorofila a e de fósforo total do que a metodologia anterior. A eutrofização também afeta o Índice de Proteção da Vida Aquática (IVA), não só por meio do índice de estado trófico, mas também da toxicidade, a qual é detectada em florações de cianobactérias ou quando da aplicação de sulfato de cobre. / Data from 1996 to 2001, from CETESB’s Surface Water Monitoring Program for the State of São Paulo, amounting to 69 sampling sites, (35 located in rivers and 34 in reservoirs)was gathered, and analyzed for chlorophyll a, nutrients and other variables used on the evaluation of the trophic status, through a modified Carlson’s Trophic State Index (TSI), (Toledo, 1983). Higher concentrations of total phosphorus were found in lotic environments, and higher values of chlorophyll a, BOD and nitrogen were registered in lentic ones. There was no significant difference between total phosphorus and total nitrogen between the dry and wet seasons. Phosphorus was the limiting nutrient in both environments. Chlorophyll a, corrected for phaeophytin a, was adopted as an indicator of phytoplanktonic biomass for reservoirs, as well as for rivers. The average ratio between chlorophyll a and phaeophytin a, was of 2:1 in reservoirs and of 1:1 in rivers. Average concentrations of chlorophyll a, calculated as geometric mean, can be used to predict trophic status as well as the probabilities of maximum values in a year period. Chlorophyll a versus total phosphorus regressions were significantly different for rivers and reservoirs, both with high correlation. The prediction of chlorophyll a through phosphorus, in reservoirs, was found to be statistically similar to the one proposed by CEPIS study, and was improved by considering the residence time information. Background values of total phosphorus, soluble orthophosphate, nitrogen, and chlorophyll a, were estimated, as well as transparency for reservoirs and turbidity for rivers, and were considered the boundaries between the oligotrophic and mesotrophic categories. New classifications of trophic status were proposed, as well as new trophic state indexes, specific for rivers and reservoirs, introducing a new trophic category, supereutrophic, which divides the eutrophic and hypereutrophic classes. These new indexes were tested with the data of 2001, 2002 and 2003, and showed higher sensibility and better agreement between chlorophyll a and phosphorus idexes, than the methodology previously used. Eutrophication, not only influences the Aquatic Biota Protection Index (IVA) through the TSI, but through toxicity, detected in cyanobacteria blooms, as well as resulting of the use of copper sulfate to control algae populations.