Numerous causes have been implicated in contributing to amphibian population declines since the 1980's, with habitat modification, ultraviolet radiation (UV-B) and environmental contaminants (such as glyphosate-based herbicide) being among the most common. This study identifies the effects of a generic glyphosate-based herbicide (GLY- 4 Plus) on mortality, immune function, body condition, and morphological plasticity of larvae of the spotted salamander (Ambystoma maculatum) under conditions that reflect open and closed canopy light regimes. Larval salamander responses to glyphosate-based herbicide varied depending on UV-B conditions. In general, it appears that an open canopy (i.e. greater UV-B exposure) may confer fitness benefits. In the presence of herbicide, survival was higher in an open canopy UV-B regime and pooled open canopy survival was higher than that of closed canopy treatments. In the absence of herbicide, body condition and immune function were positively related with amount of UV-B. Finally, herbicide presence appeared to affect morphology under low UV-B conditions. UV-induced breakdown of surfactant or a complex interaction between temperature stratification and trophic relations is potentially responsible for the observed patterns in survival and body condition. However, the mechanistic underpinnings of improved immune function and morphological differences are less clear. As deforestation is likely to continue, amphibians may find themselves in ponds with increasingly open canopies. Combined with the knowledge that some amphibians can become locally adapted to UV exposure and develop pesticide tolerance, the probability of surviving exposure to this herbicide may be elevated in open canopy ponds. These results emphasize the complexity of natural systems and the importance of including multiple factors in experiments.

Periodic monitoring of contaminant levels in fish from the Yukon Territory indicated that organochlorine (OC) contaminants had rapidly declined since the early 1990s. This study examined OC concentrations, including chlordane (sigma-CHL), sigma-DDT, hexachlorocyclohexane (sigma-HCH), toxaphene (sigma-CHB), sigma-PCB and chlorinated benzenes (sigma-CBz) in sentinel fish (species of consistent annual observation and collection) from two Yukon lakes (Kusawa, Quiet), and from the aquatic food web of a focus lake (Lake Laberge) across several temporal points between 1993 and 2003. OC analysis and phytoplankton counts from dated sediment cores as well as climate data were also collected. Population, morphological (length, weight, age), biochemical (lipid content, delta-13C, delta-15N) and OC contaminant data for fish and invertebrates (zooplankton, snails, clams) were reviewed to elucidate the primary causes for these OC declines. Although some spatial differences in contaminant levels exist between the Yukon lakes, OC concentrations were declining for lake trout in all three lakes, with declines also noted for burbot from Lake Laberge. Several other fish species as well as zooplankton from Lake Laberge exhibited decreases in contaminant levels except northern pike, which registered consistently higher levels from 1993 to 2001. There was no evidence to support the hypotheses of changes in fish trophic levels or food sources with the exception of burbot, which marginally decreased, and northern pike, which climbed a half trophic level. Through OC flux analysis in dated sediments, the hypothesis that declines in abiotic deposition affected the contaminant levels in the food web was also negated. The closure of the Lake Laberge commercial fishery resulted in faster fish growth and larger fish populations, which are contributing to biomass dilution of OC concentrations, higher OC biomagnification factors for some species and likely changes in predator-prey interactions as resource competition increases. The large ratio of OC decreases in the lower vs. higher trophic levels of Lake Laberge have increased food web magnification factors (FWMF) for all six OC groups. It is also suspected that above-average temperatures and below-average precipitation in the lower Yukon region over the 1990s may have contributed towards an increase in lake primary production resulting in biomass dilution of contaminants in zooplankton for all three study lakes. Concurrently, shifts in the Lake Laberge zooplankton community, from climate fluctuations or increased fish predation, have gone from an abundance of Cyclops scutifer in 1993 to dominance by Diaptomus pribilofensis in 2001, although sample sites were limited. Characteristics specific to each species (e.g. body size, composition and metabolism) likely play a role in the significant OC declines measured in zooplankton. Fluctuations in population dynamics, species characteristics and OC contaminant concentrations in the Lake Laberge ecosystem may continue for several years to come. Sentinel species such as lake trout, burbot, whitefish, cisco and plankton should continue to be monitored in all three Yukon lakes for future temporal correlations with contaminants or climate change.

The induction of hepatic cytochrome P4501A1 and its monooxygenase activity 7-ethoxyresorufin O- deethylase, (EROD) in fish by PAHs, PCBs and dioxins has been suggested as an early warning system &ldquo / most sensitive biochemical response&rdquo / for assessing environmental contamination conditions. In this study, the degree of induction of cytochrome P4501A1 protein as determined immunochemically and CYP1A1 associated EROD activity in fish were utilized as biomarkers of exposure to PAHs, PCBs and related organic pollutants along the izmir Bay on the Aegean Sea Coast after the Great Canal Project. Three different fish species were used throughout this study, namely leaping mullet (Liza saliens), annular seabream (Diplodus annularis) and common sole (Solea vulgaris) which were representatives of pelagic, benthopelagic and benthic fish, respectively. Fish were sampled in November 2002 and October 2003 from different sites of the Bay. The mullet caught from Harbor, &Uuml / &ccedil / kuyular port site, and Pasaport region displayed highly elevated EROD activities which were 2258&plusmn / 840 (n=15), 2011&plusmn / 490 (n=4), 1813&plusmn / 287 (n=11) pmole /min/mg protein, respectively and were 104, 80 and 79 fold higher than that of fish obtained from the reference point (25&plusmn / 9 pmole/min/mg protein / n=4). Mullet caught along the pollutant gradient at three other sites (Hekim Island, inciralti, and Zeytinalani) exhibited less but highly significant induced EROD activity. EROD activities of common sole sampled from Fo&ccedil / a open sites (107&plusmn / 20 pmol/min/mg protein, n=5) and site16A (80&plusmn / 12 pmol/min/mg protein, n=9) were found to be very low and the latter was accepted as reference site. The highest EROD activity were seen in fish captured from inciralti which was about 6.3 times higher than those obtained from reference site. Common sole caught from the mouth of Gediz River and Hekim Island exhibited also highly elevated EROD activities. Annular seabream was tested to monitor CYP1A inducing chemicals for the first time in this study. The highest EROD activity (1376&plusmn / 279 pmol/min/mg protein, n=8) were detected in fish samples collected from Harbor region. An inverse relationship was found between distance to the harbor region and EROD activities of annular seabream captured from other sampling sites. In this study for the first time, major cytochrome P450 dependent mixed function oxidase activities such as benzphetamine N- demethylase, ethylmorphine N-demethylase and aniline 4- hydroxylase, were characterized in annular seabream. Changes in the P450 1A1 protein level were determined by immunochemical analysis to monitor the pollutant based induction in all fish species and good correlation was obtained between EROD activity and CYP1A protein content. Fish from polluted sites had both highly induced EROD activity and cytochrome P450 1A content. Chemical analysis of total PAH concentration in sediment and liver tissues of some fish sample were also carried out. Although, izmir Great Canal Project has been active since 2000 to treat and protect the izmir Bay from the contamination of domestic and industrial wastes this study clearly demonstrated that the level of PAH, PCB and dioxin type persistent organic contaminants are still very high especially in the Inner and Middle Bay. This has implications for human fish consumption from contaminated areas, as well as for the health status of aquatic organisms.

Ecotoxicity testing of chemicals for environmental risk assessment is an area where a high number of vertebrates are used across a variety of industrial sectors. The application of the 3Rs in toxicity testing using fish address both the ethical and societal concerns around this issue in addition to the increasing legislative requests for the incorporation of animal alternatives. This thesis aims to highlight the potential of 3D cell culture models to "bridge the gap" between in vitro and in vivo screening procedures for testing of chemicals with the potential to persist or bioaccumulate thereby improving the predictive power of screening procedures. This thesis examines two alternative methods for their potential use as an intestinal based toxicokinetic tool for environmental risk assessment, utilising an in vitro fish cell line replacement tool (RTgutGC). In addition, for the first time a new intestinal primary cell culture based model was developed to address both intestine region specific response (pyloric, anterior, mid and posterior) and size related adaptability to toxins. Paramagnetic oximetry was used to measure oxygen content within 3D structures (spheroids) in order to better understand the microenvironment of these culture models. Using histology, immunohistochemistry, transepithelial electrical resistance (TEER), transmission electron microscopy (TEM), metabolic, fluorescence and gene expression assays, the comparability of this system to native intestinal response was established. Following exposure to carefully chosen environmental contaminants (Benzo[a]pyrene and Copper), the RTgutGC cell line demonstrated comparable responses to existing literature in terms of uptake, metabolism, DNA damage and the presence an equivalent saturable level. Primary enterocytes cultured on transwell inserts remained viable for upto six weeks, with permeability and metabolic activity comparable to native tissue (both in vitro and ex vivo). Taken in combination, these features of enterocytes represent a profile more closely representative of the intestine then the widely used "gut sac" method. With the potential advantages of incorporating complexity at differing levels (connective tissue layer, intestinal bacteria biome), the intestinal models described offer the potential to screen highly persistent toxins which may require prolonged incubation, in addition to the exploration of complex experimental designs which minimise animal usage (uptake, depuration, uptake). As a consequence, the models developed within this thesis significantly enrich the emerging fish based in vitro testing strategies.

A contribuição deste trabalho é apresentar uma metodologia de avaliação de risco ecológico do ambiente aquático utilizando-se dados provenientes de programas de monitoramento ambiental. O estudo tem como cenário um trecho do Rio Jacuí, município de São Jerônimo – RS, Brasil, que foi avaliado através da aplicação de um programa de monitoramento ambiental. Consideraram-se como variável explicativa deste estudo, as evidências registradas nos compartimentos abióticos, água superficial e sedimento. As evidências químicas foram decorrentes da presença dos metais Hg, Pb e Zn e as evidências ecotoxicológicas de ensaios de toxicidade aquática com Ceriodaphinia dubia para água superficial e Hyalella azteca para sedimento. Consideraram-se como variáveis respostas as evidências biológicas compostas pelos dados de riqueza, índice de Shannon-Weaver, equitatividade e densidade numérica das espécies das comunidades zooplantônica e bentônica. O risco ecológico (Baixo, Médio e Alto) foi caracterizado pela associação à qualidade ambiental (Ótima, Alerta e Crítica), respectivamente, estabelecida pelas evidências registradas. Os resultados permitem considerar que é possível o uso de programas de monitoramento ambiental para avaliação de risco ecológico, se contiverem, além dos dados químicos e ecotoxicológicos exigidos pela legislação ambiental, dados do monitoramento da biota residente. / The contribution of this work is to present a methodology for ecological risk assessment in an aquatic environment using data derived from environmental monitoring programs. The location focused by this study was a segment of the Jacuí River, in the town of São Jerônimo – RS, Brazil, which was assessed by applying an environmental monitoring program. The evidence recorded from the abiotic compartments surface water and sediments was considered an explanatory variable. The chemical evidence stemmed from the presence of Hg, Pb and Zn, while the ecotoxicological evidence resulted from aquatic toxicity tests using Ceriodaphinia dubia for surface water and Hyalella azteca for sediments. The biological evidence from the Shannon-Weaver index, species richness, equitability and numerical density data in zooplanktonic and benthonic communities was considered the response variable. The ecological risk (Low, Medium, and High) was characterized by the association with environmental quality (Great, Warning, and Critical), established by the evidence recorded. The results have shown that it is possible to use environmental monitoring programs to evaluate of ecological risk assessment, if they have chemical and ecotoxicological data required by environmental laws, and monitoring data of resident biota.

La contamination simultanée des écosystèmes aquatiques par des polluants et des nutriments est un problème majeur dont les effets sur les macrophytes sont encore méconnus. L'objectif de cette thèse était d'étudier les effets de deux types de polluants : herbicides et éléments trace métalliques (ETM), en combinaison avec des ressources variables (azote, phosphore, ou carbone) sur Myriophyllum spicatum, en utilisant des paramètres provenant de l'écologie chimique et de l'écotoxicologie. Les tests ont montré des effets contrastés des herbicides sur la plante, mais pas d'effet des ETM. Dans tous les cas, les modifications de ressources (nitrate, ratio N:P ou saccharose) ont induit des effets importants sur la physiologie et la stœchiométrie de la plante, pouvant altérer ses réponses à un stress supplémentaire comme les polluants. Ces résultats suggèrent qu'un déséquilibre des ressources en présence de polluants pourrait modifier leurs effets sur les macrophytes, et soulignent également la nécessité d'ajouter des paramètres plus informatifs dans les tests afin de répondre aux enjeux du stress multiple et améliorer l'évaluation du risque environnemental / Simultaneous contamination of aquatic ecosystems by pollutants and nutrients is a major problem whose effects on macrophytes are still unknown. The objective of this thesis was to study the effects of different pollutants, herbicides and trace metal elements (TME), in combination with varying resource availability (nitrogen, phosphorus, or carbon) on Myriophyllum spicatum, using parameters from chemical ecology and ecotoxicology. Tests showed contrasting effects of herbicides, but no effects of the TME. In all cases, resource modifications (nitrate, N:P ratio or sucrose) induced significant effects on the physiology and stoichiometry of the plant, which might alter its response to additional stress like pollutants. These results suggest that an imbalance of resources in the presence of pollutants may lead to unforeseen changes in the combined effects on macrophytes, and also highlight the need to add more informative parameters in tests to meet the challenges of multiple stress and improve environmental risk assessment.

Made available in DSpace on 2014-06-11T19:26:05Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-02-24Bitstream added on 2014-06-13T18:29:25Z : No. of bitstreams: 1 silva_mia_me_sjrp.pdf: 1214450 bytes, checksum: 15f951348ff6ca57eac5cbe171eeefc5 (MD5) / Os quelônios estão entre os grupos de vertebrados com maior risco de extinção, sendo as principais ameaças para as populações, a degradação e poluição ambiental. A espécie Phrynops geoffroanus, popularmente conhecida como “Cágado-de-Barbelas”, tem se proliferado em ambiente poluído, sujeita a condições adversas que podem influenciar nos seus hábitos de vida e condições fisiológicas. Estudos que monitorem os efeitos da contaminação ambiental são fundamentais para o conhecimento da biologia da espécie e delineamento de estratégias de conservação efetivas. Deste modo, as análises dos parâmetros hematológicos e bioquímicos mostram-se importantes na avaliação da saúde de animais silvestres e riscos para o animal e ecossistema. O objetivo do trabalho foi verificar a influência do ambiente na fisiologia de uma população de Phrynops geoffroanus por meio da avaliação da capacidade antioxidante e respostas aos estressores ambientais, em comparação com espécimes de local sob condições controladas. Foram avaliadas, por meio do hemograma completo, dosagem de espécies reativas ao ácido tiobarbitúrico (TBARS), ensaio da capacidade antioxidante em equivalência ao Trolox (TEAC) e atividades das enzimas antioxidantes catalase e glicose-6-fosfato desidrogenase (G6PDH), amostras sanguíneas de sessenta espécimes, sendo trinta provenientes do córrego Felicidade, ambiente poluído, no perímetro urbano de São José do Rio Preto-SP; e trinta do criatório “Reginaldo Uvo Leone”, Tabapuã-SP, local sob condições controladas, cujas amostras constituem o grupo controle dos experimentos. Houve grande variação nos parâmetros hematológicos de Phrynops geoffroanus de ambiente urbano. Os valores de glóbulos vermelhos e hemoglobina foram significantemente menores que os observados em animais do criatório (p = 0,0004; p = 0,0371, respectivamente)... / The turtles are among the most endangered vertebrates groups, and the main threats to populations are the environmental pollution and degradation. The species Phrynops geoffroanus, popularly known as Geoffroy's side-necked turtle, has proliferated in polluted environments, subject to adverse conditions that could influence their living habits and physiological conditions. Studies that monitor the effects of environmental pollution are the key to understand the species biology and design effective conservation strategies. Thus, the analysis of hematological and biochemical parameters showed to be important in assessing the health of wild animals and for the animal and ecosystem risks. This work aimed to assess the environmental influence on the physiology of a Phrynops geoffroanus population through the evaluation of antioxidant status and responses to environmental stressors, compared to specimens from a place under controlled conditions. They were evaluated by hemogram, measuring thiobarbituric acid reactive species assay (TBARS), Trolox-equivalent antioxidant capacity evaluation (TEAC) and the activities of antioxidant enzymes, catalase and glucose-6-phosphate dehydrogenase (G6PDH), blood samples of sixty specimens, thirty from the Felicidade stream, polluted environment, within the São José do Rio Preto city, and thirty from the Reginaldo Uvo Leone breeding farm, Tabapuã-SP, place under controlled conditions, whose samples constitute the control group of the experiments. There was a wide variation in hematological parameters of Phrynops geoffroanus from the urban environment. The red blood cells and hemoglobin values were significantly less than those observed in animals from breeding farm (p = 0.0004; p = 0.0371, respectively). There was significant increase of thrombocytes (p < 0.0001) and leukocytes (p < 0.0001) to the animals from the Felicidade stream... (Complete abstract click electronic access below)

A contribuição deste trabalho é apresentar uma metodologia de avaliação de risco ecológico do ambiente aquático utilizando-se dados provenientes de programas de monitoramento ambiental. O estudo tem como cenário um trecho do Rio Jacuí, município de São Jerônimo – RS, Brasil, que foi avaliado através da aplicação de um programa de monitoramento ambiental. Consideraram-se como variável explicativa deste estudo, as evidências registradas nos compartimentos abióticos, água superficial e sedimento. As evidências químicas foram decorrentes da presença dos metais Hg, Pb e Zn e as evidências ecotoxicológicas de ensaios de toxicidade aquática com Ceriodaphinia dubia para água superficial e Hyalella azteca para sedimento. Consideraram-se como variáveis respostas as evidências biológicas compostas pelos dados de riqueza, índice de Shannon-Weaver, equitatividade e densidade numérica das espécies das comunidades zooplantônica e bentônica. O risco ecológico (Baixo, Médio e Alto) foi caracterizado pela associação à qualidade ambiental (Ótima, Alerta e Crítica), respectivamente, estabelecida pelas evidências registradas. Os resultados permitem considerar que é possível o uso de programas de monitoramento ambiental para avaliação de risco ecológico, se contiverem, além dos dados químicos e ecotoxicológicos exigidos pela legislação ambiental, dados do monitoramento da biota residente. / The contribution of this work is to present a methodology for ecological risk assessment in an aquatic environment using data derived from environmental monitoring programs. The location focused by this study was a segment of the Jacuí River, in the town of São Jerônimo – RS, Brazil, which was assessed by applying an environmental monitoring program. The evidence recorded from the abiotic compartments surface water and sediments was considered an explanatory variable. The chemical evidence stemmed from the presence of Hg, Pb and Zn, while the ecotoxicological evidence resulted from aquatic toxicity tests using Ceriodaphinia dubia for surface water and Hyalella azteca for sediments. The biological evidence from the Shannon-Weaver index, species richness, equitability and numerical density data in zooplanktonic and benthonic communities was considered the response variable. The ecological risk (Low, Medium, and High) was characterized by the association with environmental quality (Great, Warning, and Critical), established by the evidence recorded. The results have shown that it is possible to use environmental monitoring programs to evaluate of ecological risk assessment, if they have chemical and ecotoxicological data required by environmental laws, and monitoring data of resident biota.

Resumo: Um dos problemas da aqüicultura é a ocorrência freqüente de infecções por parasitos e bactérias, principalmente em sistemas de criação intensiva. Entre os antibióticos, a oxitetraciclina (OTC) e o florfenicol (FFC) são os mais usados para tratar infecções causadas por bactérias em peixes. Os objetivos foram estimar a concentração letal 50% (CL50;48h) da OTC (Terramicina®) e do FFC (Aquaflor®) para o pacu (Piaractus mesopotamicus), classificar a OTC e o FFC pelo risco de intoxicação ambiental; determinar a dose eficaz de OTC e de FFC administrada na ração para o controle da infecção por Aeromonas hydrophila em pacu; avaliar o efeito da diluição da OTC e do FFC nas variáveis de qualidade de água durante os testes de toxicidade e durante o tratamento e avaliar as alterações histopatológicas após o tratamento com OTC e FFC. Para os testes de toxicidade aguda os animais (peso entre 0,5 e 1,0 g) foram expostos a 7,0; 7,5; 8,0 e 8,5 mgL-1 de OTC ou a 600,0; 700,0; 800,0; 900,0 e 1000,0 mgL-1 de FFC e um tratamento controle. A OTC e o FFC foram classificados pela toxicidade aguda e pelo risco ambiental de acordo com as classes de valores de CL50;48h. Para o tratamento de infecção induzida por A. hydrophila (3.0 x108 bactéria.mL-1), foram realizados dois testes, um com OTC (110,0; 140,0 e 170,0 mg.Kg-1) e outro com FFC (5,0; 10,0 e 15,0 mg.Kg-1). Os tratamentos foram três concentrações de cada antibiótico, um controle sem infecção e um com infecção. Para análise histopatológica foram coletados fragmentos de brânquia, fígado, rim e pele dos peixes após o tratamento com os antibióticos. As variáveis de qualidade de água registradas diariamente foram pH, temperatura, condutividade elétrica e concentração de oxigênio dissolvido, nos testes de toxicidade aguda e durante os testes de concentrações curativas. Nos testes de toxicidade aguda, a CL50;48h... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: One of the main problems of modern aquaculture is the occurrence of infection of farmed fish by parasites and bacteria, especially in intensive systems. Among the antibiotics, the oxytetracycline (OTC) and the florfenicol (FFC) are the most commonly used to treat infections caused by bacteria in fishes. The objective was to estimate the 50% lethal concentration (LC50, 48h) of OTC (Terramycin®) and of the FFC (AQUAFLOR®) for the pacu (P. mesopotamicus), classify the OTC and FFC of according the assessment risk and to determine the effective concentration of OTC and of FFC administered in feed for control of Aeromona hydrophila in pacu; to evaluate the effect of dilution of OTC and of the FFC in variables in water quality during toxicity tests and for treatment and to evaluate the histopathological changes after treatment with OTC and FFC. For acute toxicity tests the animals (weighing between 0.5 and 1.0 g) were exposed to 7.0, 7.5, 8.0 and 8.5 mg.L-1 OTC or 600.0, 700 , 0, 800.0, 900.0 and 1000.0 mg.L-1 of FFC and a control treatment. The OTC and the FFC were classified for acute toxicity and for environmental risk of according with the ranking of value of LC 50;48h. For the treatment of A. hydrophila induced by experimental infection (3.0 x108 bactéria.mL-1), were carried out two tests, one with OTC (110.0, 140.0 and 170.0 mg.Kg-1) and another with FFC (5.0; 10.0 and 15.0 mg.Kg-1). The treatments included three concentration of antibiotic, a control without infection and a with infections. For histopathological analysis were collected gill tissue, liver, kidney and skin of fish after the treatment of bacterial diseases with antibiotics. The water quality variables were recorded daily pH, temperature, electrical conductivity and dissolved oxygen in acute toxicity tests and during treatment. In tests of acute toxicity, the LC50;48h estimated of OTC for pacu was... (Complete abstract click electronic access below) / Orientador: Joaquim Gonçalves Machado Neto / Coorientador: Claudinei da Cruz / Banca: Pedro Antonio Zagatto / Banca: Flávio Ruas de Moraes / Mestre

Experimentos em mesocosmos, por se tratarem de estudos in-situ, possibilitam extrapolar para o campo, investigações realizadas em menor escala, com maior seguridade. Em fevereiro de 2002, foram instalados às margens da represa do Lobo (22º15\'S e 47º49\'W) nove mesocosmos, construídos com plástico (PVC) em forma de hexágono com 2 metros de altura, com fundo aberto em contato com o sedimento e volume variando entre 4,5 e 5,1 m3, em função da declividade do terreno. De acordo com a resolução 20/86 do Conselho Nacional do Meio Ambiente, as concentrações máximas permitidas para os metais cobre (0,02 mg/L) e cromo (0,5 mg/L) em corpos d\'água Classe 2 foram adicionadas aos mesocosmos, originando-se triplicatas, adotando-se outros três mesocosmos como controles. O objetivo principal deste trabalho foi verificar as possíveis alterações no ambiente sedimento, particularmente o enriquecimento e a indução de toxicidade, em função da adição dos metais mencionados. Para tanto, amostras foram coletadas através de dragas e testemunhos nos tempos 0 dia (antes da contaminação), 10 dias, 20 dias e 30 dias após a contaminação (final do experimento). Em seguida, as amostras foram preparadas e submetidas às análises físicas e químicas, caracterização da macrofauna bentônica e diversos ensaios toxicológicos. A partir dos dados gerados, efetuou-se o estudo integrativo da tríade de qualidade de sedimentos. Os resultados obtidos mostraram um discreto aumento na concentração total dos metais cobre e cromo nos sedimentos dos mesocosmos contaminados em comparação aos controles, sendo verificada diminuição na abundância de organismos bentônicos e efeitos tóxicos sobre os organismos-teste submetidos a estes sedimentos. As respostas da tríade foram essenciais para a caracterização da qualidade dos sedimentos dos mesocosmos controle em relação aos dos mesocosmos contaminados. / In-situ mesocosms experiments allow the extrapolation of laboratory data to the field with high reliability. In the present study, nine hexagonal PVC mesocosms with 2 m height and 4.5 to 5.1 m3 volume were installed in contact with the sediment near the Lobo reservoir dam (22º15\'S e 47º49\'W) in february of 2002. In accordance with the National Environmental Council (CONAMA) 20/86 resolution for Class 2 water bodies, the maximum allowed concentrations of copper (0,02 mg/L) and chromium (0,5 mg/L) were added to the mesocosms (triplicate), and three other ones were used as controls. The main purpose of this study was to evaluate the possible changes in the sediment environment, particularly the enrichment and induction of toxicity, by the contamination of these metals. The sediment was sampled by means of Eckman-Birge and core samplers on the 0 (before the contamination), 10th, 20th and 30th days (end of the experiment). Afterwards, physical and chemical analyses, benthic macrofauna characterization and several toxicity assays were conducted with the samples. In order to better evaluate these results, the sediments quality triad was considered. A discrete increase in the total concentration of copper and chromium was observed in the sediments of the contaminated mesocosms when compared to the controls, as well as a reduction in the abundance of benthic organisms and toxic effects over the organisms tested with these sediments. The triad responses were essential for quality characterization of the control mesocosms sediments in comparison with the contaminated ones.