M.Sc. / A general introduction provides the foremost morphological characteristics of the genus. A breeding colony of Argulus japonicus was kept under laboratory conditions in order to study sperm transfer. Pairs in copula were studied with histology and scanning electron microscopy. Sections of copulating pairs revealed sperm on the accessory copulatory structures of the male; and scanning electron microscopy showed that sperm transfer occurs in three phases which can be differentiated to ten different stages. Sperm transfer occurs via a spermatophore in A. japonicus. This is the first observation of a spermatophore in Argulus. For the second part of this study, seven specimens of an unknown freshwater ectoparasitic crustacean were collected from red tilapia fish, kept for consumption at the “Langat Fishing, Seafood and Beer Garden” Restaurant just off the Langat River in Selangor, Malaysia. Initial investigation showed that the specimens were of the genus Argulus. Light and scanning electron microscopical studies were subsequently used to identify the species. A comparison with all Argulus species formerly described from Asia and the surrounding islands was conducted. The species was identified as Argulus coregoni, due to the presence of the roughly triangular shaped anterior respiratory areas and the kidney bean shaped posterior respiratory areas. Additionally, the abdomen with sharply pointed terminal ends as well as the presence of characteristic accessory protrusions on the second ii swimming leg of the male specimens confirmed this identification. This species has not previously been described from Malaysia. The final chapter of this dissertation contains an overall summative discussion of the different parts of this study and highlights future possible research avenues.

Ph.D. / The Branchiura is a group of ectoparasitic crustaceans which infect mostly fishes. The subclass contains four genera including Argulus, Chonopeltis, Dolops and Dipteropeltis. Despite their reputation as pests our understanding of their biology is meager. In the first part of the study the anatomy and physiology is described. The species studied include Argulus japonicus, Dolops ranarum and Chonopeltis australis. Live specimens of A. japonicus, D. ranarum and Chonopeltis australis were collected, fixed in Todd‟s fixative and processed for transmission electron microscopy. The results gleaned from A. japonicus and D. ranarum indicated that the ultrastructure and physiology of the cells were similar to the digestive epithelia of free-living copepods. The anterior midgut consists of Resorptive cells (R cells) and the enteral diverticula consist of two cell types including R and Fibril cells (F). The R cells contain lipid droplets and F cells contain rough endoplasmic reticulum indicating that the absorption of nutrients and digestion occurs in the anterior midgut and enteral diverticula. The lipid droplets in both species are large in size and number. Blister cells/B cells and R‟ (apostrophe) cells occur in the posterior midgut and are involved in the processing of digestive waste. The results from C. australis were different from A. japonicus and D. ranarum and reveal the possible presence of F/R cells with multiple functions of both absorption and enzyme secretion. The cells contain few lipid droplets and instead contain many hexagonal-shaped crystalline structures that are interpreted to be proteinaceous. The differences in diet are thought to be influenced by morphological differences in the feeding appendages. The second part of the study involved the supraoesophageal ganglion or brain of C. australis. This genus is unique among the Crustacea since the antennules are absent. This trait poses implications regarding the brain morphology since particular parts of the brain impart nerves that innervate certain appendages in arthropods. Specifically the deutocerebrum or midbrain innervates the antennules. A study was conducted to discover whether the antennular nerves were absent. Specimens of C. australis were fixed in AFA, sectioned and stained with Heidenhain‟s AZAN. Results showed that the antennular nerves were absent and the deutocerebrum was smaller in comparison to the other brain segments indicating degeneration. Moreover, C. australis possesses a reduced number of sensory sensilla on its external surface compared to related genera. The loss of antennules does not affect its sensory capabilities in host searching. However, the reduced numbers of sensilla and its feeble swimming capabilities are more likely to reduce its efficiency in host searching.

Ph.D. / The Branchiura is a group of ectoparasitic crustaceans which infect mostly fishes. The subclass contains four genera including Argulus, Chonopeltis, Dolops and Dipteropeltis. Despite their reputation as pests our understanding of their biology is meager. In the first part of the study the anatomy and physiology is described. The species studied include Argulus japonicus, Dolops ranarum and Chonopeltis australis. Live specimens of A. japonicus, D. ranarum and Chonopeltis australis were collected, fixed in Todd's fixative and processed for transmission electron microscopy. The results gleaned from A. japonicus and D. ranarum indicated that the ultrastructure and physiology of the cells were similar to the digestive epithelia of free-living copepods. The anterior midgut consists of Resorptive cells (R cells) and the enteral diverticula consist of two cell types including R and Fibril cells (F). The R cells contain lipid droplets and F cells contain rough endoplasmic reticulum indicating that the absorption of nutrients and digestion occurs in the anterior midgut and enteral diverticula. The lipid droplets in both species are large in size and number. Blister cells/B cells and R' (apostrophe) cells occur in the posterior midgut and are involved in the processing of digestive waste. The results from C. australis were different from A. japonicus and D. ranarum and reveal the possible presence of F/R cells with multiple functions of both absorption and enzyme secretion. The cells contain few lipid droplets and instead contain many hexagonal-shaped crystalline structures that are interpreted to be proteinaceous. The differences in diet are thought to be influenced by morphological differences in the feeding appendages. The second part of the study involved the supraoesophageal ganglion or brain of C. australis. This genus is unique among the Crustacea since the antennules are absent. This trait poses implications regarding the brain morphology since particular parts of the brain impart nerves that innervate certain appendages in arthropods. Specifically the deutocerebrum or midbrain innervates the antennules. A study was conducted to discover whether the antennular nerves were absent. Specimens of C. australis were fixed in AFA, sectioned and stained with Heidenhain's AZAN. Results showed that the antennular nerves were absent and the deutocerebrum was smaller in comparison to the other brain segments indicating degeneration. Moreover, C. australis possesses a reduced number of sensory sensilla on its external surface compared to related genera. The loss of antennules does not affect its sensory capabilities in host searching. However, the reduced numbers of sensilla and its feeble swimming capabilities are more likely to reduce its efficiency in host searching.

The farming of Atlantic salmon (Salmo salar) is challenged by parasitic infestations caused by Lepeophthreirus salmonis and Caligus elongatus. A convenient and effective way to control sea lice and treat farmed salmon is by in-feed treatments such as Slice®. A reliable, accurate and reproducible method for the determination of emamectin benzoate (EB), the active ingredient of Slice®, and its desmethylamino metabolite (DES) in sediment was developed and validated. It involved methanolic extraction, clean-up using solid-phase extraction with a strong cation exchanger, and derivatisation with trifluoroacetic acid anhydride and N-methylimidazole. Analytes were quantified following HPLC separation with fluorescence detection. The method was successfully applied to determine EB and DES in salmon flesh and skin, seawater, mussels (Mytilus edulis) and seaweed (Palmaria palmata). A laboratory study showed that EB was persistent under anaerobic conditions in two different sediments at 4 and 14 ºC. A further study also demonstrated that the growth of seaweed (P. palmata) was not affected by the presence of EB and that EB did not accumulate significantly in the seaweed. This result is encouraging in view of proposed polyculture systems involving seaweeds. Studies conducted on a working Scottish salmon farm investigated the fate of EB and DES in target and non-target matrices. For three months post-treatment, EB was detected, by mass in descending order, in the salmon flesh, skin, faeces, then mucus and sea lice with concentrations in each matrix declining steadily over the period. As EB had never been quantified in sea lice before, it was unclear whether they were a significant sink for EB in the environment, following their exposure to the medicine and dislodging from salmon after feeding. However, due to the low concentrations of EB detected in the sea lice, faeces are most probably the main route for emamectin entering the environment. Sediment collected directly below and around two active walkways, over five or six months following treatment, showed that the spatial dispersion of EB and DES was mainly limited to the area within 25 m of the cage edge, although concentrations depended on sampling location in relation to water currents. Maximum EB concentrations were recorded three months after treatment. Seven days after treatment, 6 % of the total EB input was present in the sediments within 25 m of the cage edge. Neither EB nor DES were detected in seawater, mussels, periwinkles, dogwhelks and seaweed samples collected from the walkway and the surrounding environment. This work, one of the few studies of the uptake of EB by indigenous fauna and flora of an active salmon farm, suggests that it is not significantly accumulated in matrices outwith the target organism and the sediment.

Submitted by Renata Lopes (renatasil82@gmail.com) on 2016-10-06T19:00:34Z No. of bitstreams: 1 haroldolobodossantosnascimento.pdf: 3868832 bytes, checksum: b4398e42d1a17af79bda9794eeb63bc3 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2016-10-07T12:17:02Z (GMT) No. of bitstreams: 1 haroldolobodossantosnascimento.pdf: 3868832 bytes, checksum: b4398e42d1a17af79bda9794eeb63bc3 (MD5) / Made available in DSpace on 2016-10-07T12:17:02Z (GMT). No. of bitstreams: 1 haroldolobodossantosnascimento.pdf: 3868832 bytes, checksum: b4398e42d1a17af79bda9794eeb63bc3 (MD5) Previous issue date: 2009-02-06 / FAPEMIG - Fundação de Amparo à Pesquisa do Estado de Minas Gerais / Os representantes da classe Oligochaeta são de grande importância para os ecossistemas dulciaquícolas, pois além de participarem do processo de mineralização da matéria orgânica, fazem a mistura do sedimento, transportando substâncias profundas para a superfície e tornando-as disponíveis a biota. Dentre os oligoquetas que habitam ambientes límnicos, destaca-se a família Tubificidae, na qual diversas espécies representantes são amplamente estudadas como indicadoras de ambientes poluídos (por exemplo, Tubifex tubifex, Limnodrilus hoffmeisteri e Branchiura sowerbyi). A biologia dessas espécies tem sido objeto de pesquisas em diversos países, porém no Brasil, apesar dos relatos de ocorrência, há uma carência considerável de trabalhos sobre este assunto. Com isso, o presente trabalho teve como objetivo estudar os atributos biológicos de L. hoffmeisteri e B. sowerbyi, oriundos de ambientes aquáticos brasileiros. Para tanto, foram realizados dois experimentos com L. hoffmeisteri: o primeiro para avaliar a influência da temperatura na reprodução e o segundo a influência da biomassa corporal na produção de casulos. Além destes, duas populações, de 30 organismos cada, cultivadas a 25 ± 1°C e em duas frações granulométricas de areia, foram observadas durante um período de 25 semanas, contadas a partir da eclosão do jovem, para verificar o tempo de maturação sexual, crescimento e reprodução da espécie. Já para B. sowerbyi, uma observação de 52 semanas foi realizada para uma população de 30 indivíduos mantida a 25 ± 1°C, tendo como objetivos verificar também a taxa de crescimento, tempo de maturação sexual e taxa de reprodução. A partir dos resultados, verificou-se que a temperatura tem influência na reprodução de L. hoffmeisteri, com maior produção de casulos a temperaturas mais elevadas (25 ± 1°C). Para alguns autores esse fato pode ser utilizado como um parâmetro para indicar poluição térmica em regiões temperadas. Além da temperatura, a biomassa corporal também teve influência na produção de ovos, sendo esta diretamente proporcional ao peso corporal do organismo. Com as observações realizadas durante as 25 semanas, foi possível determinar (valores para areia fina e média respectivamente): tempo de eclosão (8 a 12 dias, para os dois substratos testados), taxa média de crescimento diário (2,14 ± 0,75 e 2,04 ± 0,42%), tempo de maturação sexual (7,17 ± 2,93 e 9,00 ± 2,00 semanas) e número de casulos produzidos por adulto por dia (0,37 ± 0,22 e 0,23 ± 0,24 casulos) de L. hoffmeisteri. De acordo com os resultados, não foi possível afirmar que a espécie se desenvolva melhor em areia de granulometria fina ou média. Já a espécie B. sowebyi, apresenta dois ciclos anuais de reprodução, sendo o primeiro mais expressivo que o segundo   em relação ao número de casulos, visto que a postura foi constante durante o primeiro ciclo e inconstante no segundo. Os resultados do presente estudo revelaram aspectos sobre os atributos biológicos de duas espécies de tubificídeos (L. hoffmeisteri e B. sowerbyi), ainda pouco estudadas no país, os quais podem ser incorporados em futuros estudos ecológicos. / The organisms of the Oligochaeta Class are very important for the aquatic ecosystems, because they both participated in the organic matter mineralization and mixed the sediment, transporting substances deep into the surface, making them available to the biota. Among the limnic oligochaetes, stands the family Tubificidae, in which several species are widely recognized as indicators of organic pollution in aquatic environments (eg. Tubifex tubifex, Limnodrilus hoffmeisteri and Branchiura sowerbyi). The biology of these species has been researched in many countries, but in Brazil, despite the reports of occurrence, there is a lack of studies on their biologies. Thus, the present work aimed to gather information about biological attributes of L. hoffmeisteri and B. sowerbyi from Brazilian aquatic environments. To this end, two experiments involving L. hoffmeisteri were conduced, the first for assess the influence of the temperature on the reproduction and the second the influence of the biomass body on the production of cocoons. In spite of these experiments, two 30-individual populations, cultured in two granulometric fractions of sand and kept at 25 ± 1°C, were observed, during 25 weeks for verify the time spent for reach the maturity, growth and reproduction rate, for the two types of substrate. For B. sowerbyi, a 52-week observation was made for a 30-individual population, aiming to verify the same objectives describes for the other species. From the results, verified that the temperature has great influence on the reproduction of L. hoffmeisteri, a great production of cocoons was recorded at high temperatures. For some authors, this fact could be used as a parameter to indicate thermal pollution in temperate regions. Besides the temperature, biomass body also had an influence on eggs production, which is directly proportional to the weight of the organisms. From the observations during the 25 weeks, it was possible to determine (for fine sand and medium sand, respectively): hatching time (8 to 12 days, for both sediments), the mean specific daily growth rate (2.14 ± 0.75 e 2.04 ± 0.42%), maturation time (7.17 ± 2.93 e 9.00 ± 2.00 weeks) and the mean number of cocoons laid per adult per day (0.37 ± 0.22 e 0.23 ± 0.24 cocoons) for of L. hoffmeisteri. According the results, it isn’t possible to affirm that this species develops better in one of the substrates types tested. B. sowerbyi, according the results of the 52 weeks of observation, shown two annuals reproductive cycles, the first been more expressive, in the number of cocoons, than the second, since the posture of cocoons was constant during all the first cycle and inconstant during the second one. The results of the present work revealed important aspects of the biological attributes of two tubificids species   (L. hoffmeisteri and B. sowerbyi), little studied in Brazil, that should be incorporated into futures ecologies researches.

The use of wrasse (Pisces: Labridae) as cleaner fish to combat infections with the parasitic copepods Lepeophtheirus salmonis (Kroyer) and Caligus elongatus (Nordmann) (sea-lice) in the culture of Salmo salar L. (Atlantic salmon) is now common. Infections with these parasites has caused considerable losses in the industry since its formative years. The use of the wrasse species Ctenolabrus rupestris (L. ) (goldsinny), Centrolabrus exoletus (L. ) (rockcook), Symphodus melops (= Crenilabrus melops) (L. ) (corkwing) and Labrus mixtus L. (cuckoo) as cleaner fish was first suggested in 1988. The use of these species in the industry is now widespread in Scotland, Ireland and Norway. The fish used are normally caught from the wild before being stocked with S. salar smolts during their first year at sea. The fish are routinely collected from waters close to the farm sites to be stocked. As most of the S. salar sea production sites in Scotland are located on the west coast of the country, the wrasse to be used in these sites are normally collected from these waters. The movement of wild fish into farm pens presents a risk of disease transfer from wrasse to S. salar and vice versa. Prior to their use as cleaner fish, these four species of wrasse had received little attention as subjects of scientific study. As a result, there was very little information available in the literature regarding their diseases. The present study was undertaken to investigate the potential pathogens present in wild populations in Scottish coastal waters, and, in particular, which of these pathogens, if any, could be transmitted to the S. salar. The study also investigated the susceptibility of wrasse to the two major viral diseases of S. salar to which they would be exposed in pens. In order to fully assess the pathogenicity of the potential disease agents under farm conditions, it was first necessary to establish the normal morphology of the wrasse species. Hence, a study of the morphological features of wrasse, with particular emphasis on those features important in the health of the fish was undertaken. Wrasse were shown to differ in many aspects from salmonids but shared many morphological features with other perciforme fish. Major differences from salmonids were evident in the skin, fins, pancreas, intestine, gonads and heart. There were also aspects of their morphology which differed from other perciforme fish, notably the structure of the heart. These features were regarded to be adaptations to the specific demands of their feeding strategies and habitats. This study was the first of its kind undertaken for wrasse and showed some early contraindications for the use of wrasse in culture; most notable was the marked lipid accumulation in, and resultant degeneration of, the liver resulting from the consumption of high energy S. salar feeds. Once the normal morphological features were established, it was possible to examine the disease status of wrasse. Wild fish were sampled from three different locations on the west coast of Scotland. These sites were all geographically distinct and were all used as sources of wrasse for the S. salar farming industry. Samples of wrasse were also obtained from farm sites supplied with wrasse from these wild sites, and an additional number of other geographically distinct farm locations. As a comparison wrasse were also obtained from a wrasse captive breeding facility and another captive location unrelated to the S. salar industry, a public aquarium. The fish from all of these sampling sites were examined fully for the presence of parasites, bacteria and, in some cases, viruses. Histological examination was also carried out on all of the fish studied. A total of 24 new parasite host records, and two tentative ones, were recorded from the four wrasse species studied. These new parasite records included protozoa, digeneans, nematodes and crustacea. Parasite infections were found to vary in prevalence, abundance and intensity in respect to the geographical characteristics of sampling sites and also the length of time spent in S. salar pens. It was concluded that the separation of wrasse from their natural diet and habitat influenced the degree of parasitism. None of the parasites found to infect wrasse were observed to cause any significant pathology in their hosts other than localised tissue responses. The possibility of transfer of wrasse parasites to S. salar was also investigated experimentally in a series of infections in which parasites dissected from wrasse were introduced to S. salar smolts by means of a novel gavage method. None of the parasites used established in the S. salar, indicating that there is little risk of transfaunation of parasites between wrasse and S. salar. However, this aspect requires further work due to the low number of parasites available and the subsequent low numbers of S. salar infected. Bacterial isolates were obtained from wrasse held in S. salar pens but were not found in any of the fish collected from the wild. Most of the bacterial strains isolated would normally be considered as opportunistic pathogens of fish. It was concluded that the relatively high levels of stress, both environmental and physical, that wrasse are subjected to under farm conditions were instrumental in the number of bacterial infections seen in wrasse. Only one pathogenic bacterial infection was seen in any of the fish sampled. This was an isolate of Aeromonas salmonicida, the agent known to cause the disease furunculosis, isolated from a wrasse obtained from one of the farm samples. Other authors have reported that this bacterium has already caused substantial losses of wrasse under farm conditions. It was concluded that Aeromonas salmonicida will prove to be a major pathogen of wrasse held in S. salar pens. No viruses wereI isolated from any of the wrasse studied. The susceptibility of wrasse to the most significant pathogens of S. salar under farm conditions was also subjected to investigation. In addition to sea-lice infection, the industry lists Infectious Pancreatic Necrosis (IPN) and Pancreas Disease (PD) as of primary importance for further research. Both of these diseases cause substantial losses in the industry. The susceptibility of wrasse to both of these disease conditions was investigated by means of experimental infections. In the case of IPN wrasse were infected by bathing with two different infective doses, a low dose which would be expected to induce the disease in S. salar parr and a second dose substantially higher than the first. The C. rupestris used were found to be susceptible to IPN. The wrasse developed some of the pathological characteristics typical of the disease in S. salar, however, other pathological signs were peculiar to wrasse. The recovery rate from the disease seen in wrasse was far more rapid than that recorded from S. salar. Shedding of the virus in the faeces of infected C. rupestris was also demonstrated. This study has illustrated for the first time the susceptibility of wrasse to IPN and that they can shed the virus in their faeces. This suggests that infected wrasse could be a source of continual reinfection in an affected sea site. Experimental infections of C. rupestris with PD followed a standard protocol for the reproduction of the disease in S. salar. Infection was by means of intraperitoneal injection with putatively infective material obtained from S. salar affected with PD. Two infection doses were used, the lowest dose used had been proven to be effective in inducing the disease in S. salar parr while the second dose, ten times higher than the first, had been shown to be effective in reproducing PD in S. salar smolts. The C. rupestris infected did not develop any of the typical signs of the disease seen in S. salar. It was, therefore, concluded that wrasse were not susceptible to PD.

Os estudos ecológicos, com vistas para a conservação do meio ambiente, vêm sendo intensificados desde meados do século XX. Devido à integração com várias outras ciências durante o processo de formação do conhecimento ecológico, esses estudos têm se tornado essenciais para o desenvolvimento de tecnologias e de políticas adequadas ao gerenciamento dos recursos naturais, em especial dos recursos hídricos. Estudos que contemplem a comparação entre sistemas naturais e artificiais são importantes na medida em que permitem investigar como esses sistemas reagem a perturbações antropogênicas de curto ou longo prazo. Há um consenso geral de que a camada de sedimento dos corpos d\'água desempenha um papel fundamental na dinâmica de transporte, acumulação e disponibilização de contaminantes nesses sistemas. A tríade de qualidade de sedimento é considerada uma das melhores abordagens para o estudo de sistemas aquáticos impactados por efluentes oriundos de atividades antrópicas. Habitats dulcícolas são particularmente suscetíveis à introdução de espécies exóticas de invertebrados. Uma possível rota de introdução dessas espécies é o cultivo em laboratório para testes de toxicidade. Substituí-las por espécies nativas com sensibilidade similar pode prevenir a introdução acidental de espécies exóticas, além de facilitar a obtenção de inóculos para as renovações da cultura, e de serem mais significativos na extrapolação dos resultados laboratoriais para situações em campo. Duas espécies nativas de organismos bentônicos foram estudadas com relação à aspectos de suas biologia e a adequação como organismos-teste em ensaios ecotoxicológicos: Chironomus xanthus (Díptera) e Branchiura sowerbyi (Oligochaeta). Os resultados dos testes de toxicidade ao pentaclorofenol para C. xanthus permitiram calcular uma CL50 (96h) de 0,111 mg/L com uma faixa de sensibilidade entre 0,082 e 0,141 mg/L. Os testes de sensibilidade de B. sowerbyi ao cloreto de potássio resultaram em uma CL50 (96h) de 0,364 g/L com uma faixa de sensibilidade entre 0,177 e 0,551 g/L. Realizou-se também um balanço energético geracional cumulativo para C. xanthus, obtendo-se os seguintes valores para as eficiências metabólicas calculadas: coeficiente instantâneo de assimilação de 98,14%, coeficiente de produção bruta de 14,76% e coeficiente de produção líquida de 15,03%. Além dos ensaios toxicológicos com os dois organismos, realizou-se um estudo comparativo entre o sistema de reservatórios em cascata do rio Tietê com o sistema de lagos naturais do Vale do Rio Doce, aplicando-se os princípios da tríade de qualidade de sedimentos. Os resultados dessa análise permitiram classificar os reservatórios estudados de acordo com o nível de qualidade ambiental sendo que o reservatório de Barra Bonita (SP) é considerado como o de pior qualidade, enquanto que os lagos do Vale do Rio Doce (MG) encontram-se ainda relativamente preservados. / The ecological studies, with views for the conservation of the environment, have been intensified from middles of the century XX. Due to the integration with several other sciences during the process of ecological knowledge formation, those studies have become essential to the development of technologies and appropriate politics for the administration of the natural resource. Studies that contemplate the comparison among natural and artificial systems are important in the way it is allowed to investigate as those systems react to antropogenic disturbances of short or long periods. There is a general consensus that the sediment of the water bodies plays a fundamental part in the transport dynamics, accumulation and disposal of pollutants in these systems. The triad of sediment quality is considered one of the best approaches for the study the influence of pollutants originated from of human activities in aquatic ecossystems. Freshwater habitats are particularly susceptible to the introduction of exotic species of invertebrates. A possible route of introduction of those species is the cultivation in laboratory for toxicity tests. To substitute them for native species with similar sensibility can prevent the accidental introduction of exotic species, besides facilitating the inocula obtaining for the renewals of the culture, and may be more significant in the extrapolation of the laboratories results for field situations. Two native species of benthic organisms were studied regarding to aspects of their biology and the adaptation as organism-test in ecotoxicological assays: Chironomus xanthus (Díptera) and Branchiura sowerbyi (Oligochaeta). The results of the toxicity tests to the pcp for C. xanthus allowed to calculate a LC50 (96h) of 0,111 mg/L with a sensitivity range of 0,082 - 0,141 mg/L. The sensitivity testes for B. sowerbyi to the KCl resulted in a LC50 (96h) of 0,364 g/L with a sensitivity range of 0,177 - 0,551 g/L. An energy budget of C. xanthus was performed, being obtained the following values for the calculated metabolic efficiencies: instantaneous coefficient of assimilation of 98,14%, coefficient of production of 14,76% and coefficient of liquid production of 15,03%. A comparative study among the system of reservoirs in cascade of the Tietê river with the system of natural lakes of Rio Doce valley was applied following the principles of the triad of quality of sediments. The results of that analyze allowed to classify the reservoirs studied in agreement with the level of environmental quality and the reservoir of Barra Bonita (SP) is considered as the one of worse quality, while the lakes of Rio Doce Valley (MG) still meet relatively preserved.

Os estudos ecológicos, com vistas para a conservação do meio ambiente, vêm sendo intensificados desde meados do século XX. Devido à integração com várias outras ciências durante o processo de formação do conhecimento ecológico, esses estudos têm se tornado essenciais para o desenvolvimento de tecnologias e de políticas adequadas ao gerenciamento dos recursos naturais, em especial dos recursos hídricos. Estudos que contemplem a comparação entre sistemas naturais e artificiais são importantes na medida em que permitem investigar como esses sistemas reagem a perturbações antropogênicas de curto ou longo prazo. Há um consenso geral de que a camada de sedimento dos corpos d\'água desempenha um papel fundamental na dinâmica de transporte, acumulação e disponibilização de contaminantes nesses sistemas. A tríade de qualidade de sedimento é considerada uma das melhores abordagens para o estudo de sistemas aquáticos impactados por efluentes oriundos de atividades antrópicas. Habitats dulcícolas são particularmente suscetíveis à introdução de espécies exóticas de invertebrados. Uma possível rota de introdução dessas espécies é o cultivo em laboratório para testes de toxicidade. Substituí-las por espécies nativas com sensibilidade similar pode prevenir a introdução acidental de espécies exóticas, além de facilitar a obtenção de inóculos para as renovações da cultura, e de serem mais significativos na extrapolação dos resultados laboratoriais para situações em campo. Duas espécies nativas de organismos bentônicos foram estudadas com relação à aspectos de suas biologia e a adequação como organismos-teste em ensaios ecotoxicológicos: Chironomus xanthus (Díptera) e Branchiura sowerbyi (Oligochaeta). Os resultados dos testes de toxicidade ao pentaclorofenol para C. xanthus permitiram calcular uma CL50 (96h) de 0,111 mg/L com uma faixa de sensibilidade entre 0,082 e 0,141 mg/L. Os testes de sensibilidade de B. sowerbyi ao cloreto de potássio resultaram em uma CL50 (96h) de 0,364 g/L com uma faixa de sensibilidade entre 0,177 e 0,551 g/L. Realizou-se também um balanço energético geracional cumulativo para C. xanthus, obtendo-se os seguintes valores para as eficiências metabólicas calculadas: coeficiente instantâneo de assimilação de 98,14%, coeficiente de produção bruta de 14,76% e coeficiente de produção líquida de 15,03%. Além dos ensaios toxicológicos com os dois organismos, realizou-se um estudo comparativo entre o sistema de reservatórios em cascata do rio Tietê com o sistema de lagos naturais do Vale do Rio Doce, aplicando-se os princípios da tríade de qualidade de sedimentos. Os resultados dessa análise permitiram classificar os reservatórios estudados de acordo com o nível de qualidade ambiental sendo que o reservatório de Barra Bonita (SP) é considerado como o de pior qualidade, enquanto que os lagos do Vale do Rio Doce (MG) encontram-se ainda relativamente preservados. / The ecological studies, with views for the conservation of the environment, have been intensified from middles of the century XX. Due to the integration with several other sciences during the process of ecological knowledge formation, those studies have become essential to the development of technologies and appropriate politics for the administration of the natural resource. Studies that contemplate the comparison among natural and artificial systems are important in the way it is allowed to investigate as those systems react to antropogenic disturbances of short or long periods. There is a general consensus that the sediment of the water bodies plays a fundamental part in the transport dynamics, accumulation and disposal of pollutants in these systems. The triad of sediment quality is considered one of the best approaches for the study the influence of pollutants originated from of human activities in aquatic ecossystems. Freshwater habitats are particularly susceptible to the introduction of exotic species of invertebrates. A possible route of introduction of those species is the cultivation in laboratory for toxicity tests. To substitute them for native species with similar sensibility can prevent the accidental introduction of exotic species, besides facilitating the inocula obtaining for the renewals of the culture, and may be more significant in the extrapolation of the laboratories results for field situations. Two native species of benthic organisms were studied regarding to aspects of their biology and the adaptation as organism-test in ecotoxicological assays: Chironomus xanthus (Díptera) and Branchiura sowerbyi (Oligochaeta). The results of the toxicity tests to the pcp for C. xanthus allowed to calculate a LC50 (96h) of 0,111 mg/L with a sensitivity range of 0,082 - 0,141 mg/L. The sensitivity testes for B. sowerbyi to the KCl resulted in a LC50 (96h) of 0,364 g/L with a sensitivity range of 0,177 - 0,551 g/L. An energy budget of C. xanthus was performed, being obtained the following values for the calculated metabolic efficiencies: instantaneous coefficient of assimilation of 98,14%, coefficient of production of 14,76% and coefficient of liquid production of 15,03%. A comparative study among the system of reservoirs in cascade of the Tietê river with the system of natural lakes of Rio Doce valley was applied following the principles of the triad of quality of sediments. The results of that analyze allowed to classify the reservoirs studied in agreement with the level of environmental quality and the reservoir of Barra Bonita (SP) is considered as the one of worse quality, while the lakes of Rio Doce Valley (MG) still meet relatively preserved.

The issue of sea lice (Lepeoptheirus salmonis and Caligus clemensii) transfer from salmon farms to wild salmon is a controversial topic in British Columbia (BC). A series of sea lice epizootics (four in five years) on juvenile chum (Oncorhynchus keta) and pink (0. gorbuscha) salmon in the Broughton Archipelago (BA), an area with the highest density of salmon farms on the west coast, have caused significant concern among conservationists, local First Nations, and the general public over the possible impacts of salmon farms on wild salmon. Key to the debate has been a lack of data on ambient sea lice infection rates on juvenile salmon in the absence of the influence of salmon farms. This work represents one of the first attempts to empirically examine ambient sea lice infection rates on juvenile salmonids. Objectives were to test hypotheses including: geographic variability is a significant factor in sea lice population dynamics, ambient sea lice infection rates on juvenile salmon are low, juvenile salmon susceptibility to sea lice infection, and the influence of salmon farms on ambient sea lice infection rates. Over a three year period, samples of juvenile chum and pink salmon (n=13.874) were collected using a beach seine net in the central coast of British Columbia (Klemtu/Bella iv Bella), a vast area with limited salmon farming activity. and with geography that allowed for simultaneous assessment in the same region of the natural interaction between sea lice and juvenile salmon and the influence of salmon farms on the interaction. Sampling was also conducted in other areas without salmon farms (Southern Gulf Islands: n=3847) and with salmon farms (Broughton Archipelago; n=3911). The results of the field experiments were also used in conjunction with laboratory experiments to examine the susceptibility of juvenile chum vs. pink salmon to infection by sea lice. The ambient lice infection rates for juvenile chum and pink salmon were up to 32% prevalence, less than one louse per fish and less than two lice per gram (prevalence: 2.0 (1.0) - 32.0 (19.0), mean lice per fish: 0.02 (0.01) - 0.67 (0.22), mean lice per gram: 0.56 (0.08) - 1.93 (0.13)). This result was found to be consistent across geographic areas with no salmon farming activity suggesting that geographic variability was not a significant factor in the natural interaction between sea lice and juvenile salmon. Salmon farms were found to strongly influence the relationship between sea lice and juvenile chum and pink salmon. Sea lice infection rates of juvenile salmon collected near salmon farms were significantly higher than non-salmon farming regions ranging from 3 - 150 times higher in the BA and from 2 - 14 times higher in the Klemtu region. Infection levels near salmon farms were variable in intensity from year to year. The extent to which the sea lice-salmon relationship was affected by salmon farms was dependent on farmed species, farm location, within year variability in fish size, and the scale of salmon farming activities within the region. The results from the laboratory and field studies demonstrate that juvenile chum salmon were more susceptible to infection by sea lice than juvenile pink salmon. However, the exact mechanism for the observed differences was not identified. Possible reasons for the observed differences could be related to genetically determined susceptibility, fish mucous differences, lethal lice infection tolerances. or other factors not examined. The results of this study suggest that the elevated sea lice infection rates observed in the BA and other areas present a significant risk to the health of wild salmon and that salmon farms are the most likely cause based on the biology and ecology of sea lice. In order to better understand the potential for salmon farms to affect wild salmon populations, it is suggested that investigations into farm level sea lice contributions be conducted in the BA and other areas where salmon farms operate. In addition, investigation into the lethal lice infection rates for juvenile salmon at early marine life size should also be conducted.