The focus of my thesis research is on the interplay between individual behavior, population dynamics and community-level processes within zooplankton communities in coastal Maine. The target organisms of my thesis work are marine copepods. Copepods are small (1-10 mm) crustaceans that perform the essential ecosystem function of consuming and assimilating primary production (phytoplankton) making it available to higher trophic levels such as commercially important fishes. Therefore, copepod population growth is of critical importance to marine food webs. Fertilization limitation has been suggested as a constraint on copepod population growth but field surveys describing the prevalence of fertilization limitation are lacking. During my doctoral research, I explored the in situ fertilization success of two marine copepod species, Temora longicornis and Eurytemora herdmani in coastal Maine. I collected monthly zooplankton samples and analyzed clutches from field-caught females using an egg-staining technique. My results indicate that both species exhibit fertilization limitation in nature and the factors correlated with their fertilization span population, community and ecosystem level factors. To determine a causal relationship between predator density and copepod mating success, I conducted laboratory experiments to assess the effects of a common mysid shrimp predator, Neomysis americana on Eurytemora herdmani mating success. I subjected males and females to predators or predator cues. I found that the presence of a mysid predator, or only a predator cue, reduced copulation frequency and spermatophore transfer leading to a 38-61% decrease in E. herdmani nauplii production. These results suggest that mysid predators can constrain copepod population growth through non-consumptive processes. To determine the effects that resources can impose on copepod behavior, I explored the behavioral and fitness consequences of Temora longicornis ingesting Alexandrium fundyense, a phytoplankton species that forms harmful algal blooms in coastal Maine. My results suggest that ingesting A. fundyense causes copepods to swim faster and with more directional persistence compared to control algae. Temora longicornis increased their average swimming velocity by 24%, which leads to a 24-54% increase in their theoretical encounter rate with predators. Therefore, these findings suggest behaviorally mediated copepod-algal interactions may have significant impacts on harmful algal bloom dynamics and the fate of toxins in marine food webs.

Thesis (M. Phil.)--University of Hong Kong, 1991.

Orientador: Marcelo Antonio Amaro Pinheiro / Resumo: O presente estudo analisa a taxonomia, morfologia externa e interna do sistema reprodutivo e crescimento relativo do camarão-fantasma Callichirus major da costa do Brasil. Para isto, espécimes de C. major foram coletados ao longo de todo o litoral brasileiro e, de forma particular, mensalmente, durante um ano, na Praia do Gonzaga, região Sudeste do Brasil. Um total de 840 indivíduos (316 machos, 524 fêmeas) foram avaliados. Ocorrendo desde o estado do Pará até Santa Catarina, C. major apresentou um rostro com duas projeções anterolaterais triangulares, pedúnculos oculares com pontas obtusas, dáctilo do quelípodo maior dos machos com uma ponta bífida e margem interna lisa, projeção proximal do carpo com margem reta, mero com porção proximal da margem dorsal dentada, quelípodo menor com borda cortante dentada e um dente grande curvado para frente entre as projeções laterais do telso. Estes animais apresentaram diferenças morfológicas marcantes em comparação aos espécimes de C. major procedentes da Florida (EUA), justificando a separação da grande população do Atlântico Ocidental de C. major e determinando uma nova espécie no gênero, Callichirus brasiliensis sp. nov. Nos capítulos desta dissertação que não trataram de taxonomia, optamos por manter o nome da espécie até o momento aceito, C. major. A morfologia reprodutiva externa destes camarões-fantasma se mostrou distinta entre machos, com gonóporos circulares, localizados no quinto par de pereiópodos, e fêmeas, com gonóporos o... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The present study analyses the taxonomy, external and internal morphology of the reproductive apparatus and relative growth of the ghost shrimp Callichirus major from the coast of Brazil. For this, specimens of C. major were collected along the entire Brazilian coast and, in particular, monthly, for one year, in Gonzaga’s Beach, Southeastern region of Brazil. A total of 840 individuals (316 males, 524 females) were evaluated. Occurring from the state of Pará to Santa Catarina, C. major presented a rostrum with two triangular anterolateral projections, ocular peduncles with obtuse tips, dactyl of the greater chelipod of males with a bifid tip and smooth internal margin, proximal projection of the carpal with straight margin, merus with proximal portion with dentate dorsal margin, smaller chelipod with toothed cutting edge and a large tooth curved forward between the lateral projections of the telson. These animals presented marked morphological differences when compared to specimens of C. major from Florida (USA), justifying the separation of the large Western Atlantic population from C. major and determining a new species in this genus – Callichirus brasiliensis n. sp. In the chapters of this thesis that don’t deal with taxonomy, we chose to keep the name of the species so far accepted, C. major. The external reproductive anatomy of these ghost shrimps was shown to be distinct between males, with circular gonopores located in the fifth pair of pereiopods, and females with ova... (Complete abstract click electronic access below) / Mestre

A análise de uma população em longo prazo permite a identificação da ausência ou presença de variações nos padrões de ciclo de vida, de distribuição espaço-temporal e dinâmica populacional. O ciclo de vida do camarão sete-barbas Xiphopenaeus kroyeri foi investigado na Enseada de Ubatuba, litoral norte do Estado de São Paulo (23º25\' - 23º27\'S / 45º00\' - 45º03\' W) ao longo de um intervalo de treze anos. Amostras de material biológico, de água de fundo e de sedimento foram coletadas em quatro pontos de amostragem em três períodos de 12 meses cada: janeiro a dezembro de 1998, julho de 2006 a junho de 2007 e setembro de 2010 a agosto de 2011. Dados obtidos em 1999 foram incluídos para as análises de crescimento individual, de longevidade e de idade de maturação. Altas abundâncias de fêmeas maduras e de jovens foram respectivamente associadas a valores de temperatura da água de fundo acima e abaixo da média da região. Indivíduos adultos predominaram em pontos com variação temporal da composição granulométrica do sedimento enquanto que os jovens se estabeleceram naqueles em que o sedimento permaneceu fino entre os períodos. Em 1998, a abundância de jovens, o peso individual de machos e fêmeas de todas as categorias demográficas, a idade de maturação morfológica e fisiológica e a longevidade foram maiores do que nos outros períodos. Os parâmetros da função de crescimento de machos e fêmeas variaram entre os períodos, sem apresentarem uma tendência temporal clara. Os padrões anuais de reprodução e recrutamento foram bastante semelhantes entre os períodos. As alterações nos fatores ambientais provocadas por variações na dinâmica de massas de água, pela ocorrência de El Niño e alterações na intensidade de pesca foram consideradas como possíveis agentes relacionadas às variações nos padrões do ciclo de vida da espécie na região / Long-term studies on a population provide detection of the presence or absence of interannual variation in patterns of its life cycle, spatio-temporal distribution, and dynamics. This study investigate the population of the seabob shrimp Xiphopenaeus kroyeri within a period of 13 years in Ubatuba Bay, northern coast of São Paulo state, Brazil (23º25\' - 23º27\'S / 45º00\' - 45º03\' W). Shrimp, bottom water and sediment samples were collected from four sampling sites during three 12-month periods: January-December 1998, July 2006-June 2007, and September 2010-August 2011. Monthly data collected in 1999 were included in growth, longevity and maturation age analyses. High abundance of mature females and juveniles were associated to the occurrence of temperature values below and above the region average, respectively. Adults predominated in sites that showed temporal variation of sediment texture while juveniles occurred in sites where sediment remained fine between the study periods. In the 1998 period values of juveniles were more abundant, individual weight of all demographic categories was higher, both morphological and physiological maturity was attained later and lifespan was longer than on the following periods. Growth function parameters of males and females varied between periods with no clear temporal trend. Monthly patterns of reproduction and recruitment were similar between the study periods. Changes in the environmental conditions caused by variations in the dynamics of the local water masses, occurrence of El Niño and fishery intensity were considered as possible factors related to the interannual variations in the life cycle pattern of X. kroyeri in the study region

Os crustáceos de água doce, confrontados com um gradiente elevado de NaCl entre a hemolinfa e o meio externo tendem a perder sal e ganhar água através das superfícies corporais. Os seus órgãos osmorreguladores, tais como as brânquias e a glândulas antenais, são responsáveis por manterem a homeostase de sal e água contra esse elevado gradiente. Para isso capturam e reabsorvem NaCl compensando as perdas difusivas de sal. Essa habilidade foi fundamental para a invasão da água doce pelos camarões palemonídeos. O objetivo deste trabalho foi investigar a biologia comparada do transporte iônico transepitelial nas brânquias camarões e caranguejos. No camarão diádromo de água doce Macrobrachium rosenbergii, as brânquias posteriores foram perfundidas com diversas salinas para experimentação eletrofisiológica. As manipulações com substituição de íons e adição de alguns inibidores do transporte iônico nas salinas perfundidas, simétricas no lado externo e interno do epitélio, demonstraram que o epitélio produz uma voltagem que pode englobar a absorção ativa (sensível ao inibidor metabólico NaCN) de Na+, que ocorre provavelmente por intermédio de um canal de Na+ ou um trocador Na+/H+ apicais sensíveis à amiloride, e é dependente da atividade de uma Na+/K+-ATPase. Uma pequena voltagem decorrente da captura de Cl- foi também medida, e se mostrou sensível à acetazolamida, um inibidor da anidrase carbônica. Esta voltagem também era sensível ao inibidor de uma V(H+)-ATPase, concanamicina, mostrando que esta bomba de prótons também desempenha um papel no transporte iônico transepitelial. Os resultados corroboram um modelo semelhante de captura de Na+ dependente de canais apicais de sódio em série com uma Na+/K+-ATPase proposto anteriormente por este laboratório. O gradiente eletroquímico produzido pela atividade desta ATPase permite a captura de Na+ na água doce. O acoplamento elétrico entre as células pilares e as células do septo branquial permite a passagem do Na+ ao longo da rota de captura até a hemolinfa. Análises das brânquias posteriores e anteriores do caranguejo de água doce Dilocarcinus pagei também foram feitas no intuito de se revelar a ultraestrutura do epitélio branquial e marcar a atividade p-NPPásica de uma Na+/K+-ATPase. Os experimentos envolvendo ultraestrutura das brânquias do caranguejo de água doce Dilocarcinus pagei mostraram, ao nível ultraestutural, uma diferenciação entre os dois lados da lamela branquial nas brânquias posteriores, aonde um lado distal apresenta características de um epitélio ionotransportador, menos desenvolvido do que no lado proximal, apesar dos dois lados mostrarem uma marcação ultracitoquímica para a Na+/K+-ATPase, indicando a ubiqüidade desta enzima. Os resultados indicam que existem dois processos fundamentais de transporte, um de Cl- e outro de Na+, demonstrados de modo eletrofisiológico e estrutural e que tal separação de processos possibilitou aos dois crustáceos estudados a invasão do ambiente dulcícola. / The freshwater crustaceans confronted with a high gradient of NaCl between the blood and the external media tend to lose salt and to gain water through the corporal surfaces. Its osmorregulatory organs, such as the gills and the antennal glands, are responsible for they maintain salt and water homeostasis against that elevated gradient. For that they capture and reabsorb NaCl compensating the difusive losses of salt. That ability was fundamental for the invasion of the freshwater by the palemoníds shrimps. The aim of this work was to investigate the compartive biology of the transepithelial ionic transport in the gills and antennal glands of shrimps and crabs. In the diadramous freshwater shrimp Macrobrachium rosenbergii, the posterior gills were perfused with several salines for electrophysiologic experimentation. The manipulations with ions replacement and addition of some ionic transport inhibitors in the perfused salines, symmetrical on the external and internal sides of the epithelium, demonstrated that the epithelium produces a voltage that can include the active absorption (sensitive to the metabolic inhibitor NaCN) of Na+, that probably occurs through a apical channel of Na+ or a Na+/H+ exchanger sensitive to the amiloride, and it is dependent of the activity of a Na+/K+-ATPase. A small voltage due to the capture of Cl- was also measured, and it was shown sensitive to the acetazolamide, an inihibitor of the carbonic anhidrase. This voltage was also sensitive to the inhibitor of a V(H+)-ATPase, concanamicine, showing that this protons pump also plays a role in the transepithelial ionic transport. The results corroborate a model similar of capture of dependent Na+ of apical channels of sodium in series with a Na+/K+-ATPase proposed previously by this laboratory. The electrochemical gradient produced by the activity of that ATPase allows the capture of Na+ in the freshwater. The electric coupling between the pillar cells and the gill septal cells allows the passage of Na+ along the capture route to the haemolymph. Analyses of the anterior and posterior gills of the freshwater crab Dilocarcinus pagei were also done in the intend to reveal the ultrastructure of the gill epithelium and to locate the p-NPPasic activity of a Na+/K+-ATPase. The experiments involving ultrastructure of the gills of the freshwater crab Dilocarcinus pagei showed, from an ultrastructural level, a differentiation among the two sides of the gill lamela in the posterior gills, where a side distal presents characteristics of an ionotransporting epithelium, more developed than the proximal side, in spite of the two sides show ultracitochemical location for Na+/K+-ATPase.

A área de ocorrência das formações Tatuí e Irati, na região centro-leste do Estado de São Paulo, entre as cidades de Leme e Rio das Pedras é objeto desta pesquisa. São detalhadas as ocorrências destas duas formações, através de seções estratigráficas, caracterizando e analisando as sucessões de litotipos, conteúdo fossilífero, tafonomia dos fósseis, além de enfocar hipóteses paleoecológicas e paleoambientais. Na FormaçãoTatuí foram identificadas quatro fácies, a inferior de arenitos finos e paleoambiente incerto, duas refletindo contexto não marinho e a de topo com influência marinha. As duas fácies do contexto predominantemente não marinho são respectivamente siltitos arenosos com fósseis de água doce e arenitos grossos ou conglomeráticos, fácies Ibicatu, localmente com lenhos. A fácies de topo é caracterizada por depósitos de arenitos finos, ocasionalmente com grandes estratificações cruzadas, estratificações \"hummockies\", apropriado para um grande corpo d\'água salino. O conteúdo fóssil da Formação Tatuí inclui três tipos de icnofósseis em três fácies diferentes (fácies basal do estudo, Ibicatu, e no topo), grandes caules vegetais (pteridófitas e espermatófitas) na fácies Ibicatu, crustáceos (conchostráceos e fragmentos indeterminados) ocorrem na fácies síltica, escamas, dentes e partes ósseas de peixes ósseos na fácies siltica e topo da Formação Tatuí. O Membro Taquaral é reconhecido por duas fácies e dois paleoambientes de salinidade variável. A fácies basal, composta de arenitos finos a conglomeráticos, granulometria irregular horizontal e verticalmente e com ictiofósseis, é interpretada como depositada em ambiente raso dominado por ondas. A segunda fácies, folhelhos sílticos, é típica de paleoambientes mais calmos, provavelmente com menor salinidade. Os fósseis da base arenosa do Membro Taquaral são peixes, representados por Chondrichthyes sob a forma de dentes cladodontes, espinhos de Euselachii (Amelacanthuse Iratiacanthus), espinhos Ctenacanthiformes (Sphenacanthus sanpauloensis eS. sp.), dentes de Xenacanthiformes, Diplodoselachidae (Taquaralodus albuquerquei) e Xenacanthidae, dentes de Orodontiformes, (Orodus ipeunaensis), Petalodontiformes (Itapyrodus punctatus eI. sp.) e Holocephali indeterminados. A fauna de Osteichthyes é a mais abundante em número de espécimes, sendo composta, predominatemente, de dentes e escamas paleoniscóides, raras escamas de Coelacanthimorpha, partes ósseas e dentes labirintodontes, estes atribuídos a Osteolepiformes e a tetrápodes Temnospondyli. Os fósseis estão normalmente dispersos e desarticulados e os elementos ósseos fragmentados e desgastados. O conteúdo fóssil da fácies folhelho síltico do Membro Taquaral é raro, os mais comuns são crustáceos, principalmente do gênero Clarkecaris, e restos muito fragmentados de Coelacanthimorpha e Palaeonisciformes. / The following Paraná Basin, Late Paleozoic lithoestratigraphic units, the upper part of the Tatuí Formation, located under the lower partof the Irati Formation, Taquaral Member are cropping out at center-eastern State of São Paulo, Brazil, between Rio das Pedras and Leme. The lithologies, fossil contents and taphonomy ofthese units are studied through stratigraphic sections, allowing the formulations of paleoecological and paleoenvironmental hypothesis. Four facies were recognized at the top of the Tatuí Formation stratigraphic sections which were interpreted as following; the basal an uncertain paleoenvironment of deposition, two paleoenvironmental contexts; mostly continental and one under deposits marine influence. The two facies interpreted as mostly continental are respectively, sandy-siltstones facies with freshwater fossils and coarse to conglomeratic sandstone, Ibicatu facies, locally with log plants. The top facies, interpreted as under a marine influence, is characterized by deposits of fine sandstones, occasionally with large cross beds, hummockies, and, locally, tidal deposits, suited for a large body, of saline water. The fossil content of Tatui Formation include three kinds of trace fossils in three different facies (basal, Ibicatu and top respectively), large stem plants (Pterydophyta and Spermatophyta) in the Ibicatu deposit, with indeterminated fragments of crustaceans and conchostraceans, found out in the siltstone facies and scales, teeth and bone pieces, found out in siltstone and of the top facies. Two facies were recognized at the Taquaral Member. The basal are fine to conglomeratic sandstone with irregularly grain size both horizontal and vertically, with ichthyofossils. Itis interpreted as laid down in a salty shallow water dominated by waves. The second are silty shale laid down in low saline water. The fossils of the sandy facies are Chondrichthyes: cladodontes teeth, Euselachii finspines (Amelacanthus and Iratiacanthus santamariaensis), Ctenacanthiformes finspines (Sphenacanthus sanpauloensisand S.sp.), Xenacanthiformes teeth, Diplodoselachidae (Taquarodus albuquerquei) and Xenacanthidae, Orodontiformes: Orodus ipeunaensis, Petalodontiformes (Itapyrodus punctatus andI. sp.) and undetermined Holocephali. The fauna of Osteichthyes, the most abundant in number of specimens are predominantly paleoniscoid teeth and scales, rare Coelacanthimorpha scales, labyrinthodonts bones and teeth, assigned to Osteolepiformes and tetrapods Temnospondyli. The fossils are usually scattered, disorganized, fragmented and worn. The fossil content of the Taquaral silty-shale facies is meager, the most common are crustaceans, mainly of the genus Clarkecaris, and very fragmented remains of Coelacanthimorpha and Palaeonisciformes.

The diversification of current aquaculture practise in South Africa is crucial for the future development of the industry. The rock lobster, Jasus lalandii has been identified as a possible candidate species for shore based culture in systems similar to those used for abalone farming. Reduced Total Allowable Catch (TAC's) and an increased minimum legal size were implemented as management strategies to relieve fishing pressure on natural stocks of J. lalandii, and in turn led to increased market demand and a possible niche for farmed lobsters. High puerulus settlement along the Namibian coast, together with other favourable aquaculture attributes, indicate that the commercial grow out of wild harvested juveniles could be feasible. The aim of study was to investigate the feasibility of growing out rock lobsters in shore based systems in Namibia and South Africa. The experimental objectives of the project were to investigate the nutritional requirements, as well as the effect of stocking density and tank design on growth and survival of J. lalandii. The economic viability of shore based rock lobster farming was then evaluated based on the experimental results and typical capital requirements of an abalone farm in South Africa. Puerulus and early juvenile rock lobsters were collected in Luderitz, Namibia and transported to HIK Abalone Farm in Hermanus, South Africa where they were acclimated in black fibre glass tanks in a flow through system. The pueruli were stocked at 50, 75, 100 and 125/m² and early juveniles at 20, 30, 40 and 50/m² to test the effect of density on growth and survival. A comparative dietary study with both size classes was conducted using a mussel diet (Choromytilus meridionalis and Mytilus galloprovincialis), a commercial shrimp feed diet and a rotational diet comprising both mussels and shrimp feed. Tanks provided with "v-shaped" asbestos hides, PVC hides and no hides were compared to test the effect on growth rate and survival of pueruli. All treatments were conducted in triplicate. Temperatures were recorded twice daily while water quality parameters were tested every second week. The results indicate that density had a significant effect on growth and survival on post-pueruli. An initial stocking density of 75 post-pueruli/m² is regarded as optimal both in terms of the growth rate and biomass production per tank. No differences in growth and survival rates were attained in the early juvenile size class. This indicates that higher densities can be used to rear juvenile J. lalandii. No significant differences were obtained in growth rate when reared under different hide conditions although asbestos hides yielded significantly higher survival rates (93.3 %) compared to the tanks provided with PVC hides (74.04 %) and no hides (77.8 %, p≤0.05). As a result of the high survival rate observed in tanks provided with "V-shaped" asbestos hides, these tanks also yielded higher biomass production per tank (297.8 grams) compared to the tanks provided with PVC hides and no hides (261.09 and 260.5 grams respectively). In the diet trials, growth rates of post pueruli and juvenile lobsters fed the mussel and rotational (mussel and shrimp feed) diets did not differ significantly, however, growth rates of lobsters fed the shrimp feed only diet was significantly lower than both the mussel and rotational diets (p≤0.05). Lobsters fed the mussel diet yielded significantly higher survival rates compared to lobsters fed either the rotational diet or shrimp feed diet only. An imbalance in the fatty acid profile of the shrimp feed could have been a major contributing factor to the poor growth and survival in lobsters fed the shrimp feed only diet as the level of linoleic acid (LOA) was exceptionally high resulting in a high (n -6):(n-3) ratio (1.01) compared to the mussel and rotational diets (0.17 and 0.56 respectively). The low level of arachidonic acid (ARA) in the shrimp feed diet could be a further contributing factor explaning for the poor growth and survival of juvenile rock lobsters. An economic feasibility study was conducted at the end of the experimental phase by modelling a hypothetical shore based rock lobster farm. A projection of production costs and revenues was based on the typical costs of a shore based abalone farm and the current market prices for wild harvested J. lalandii. The economic viability was evaluated using benefit-cost ratios, payback period, internal rate of return and breakeven analysis. Sensitivity analyses revealed that the projected lobster growth and survival rates were the main biological factors influencing the economic feasibility of the hypothetical rock lobster farm. An assumed four year grow out period at a low stocking density yielded more lucrative internal rate of return (IRR), benefit-cost ratio, payback period and net present values (NPV) than a five year grow out period at a high density. The four year grow out scenario proved to be more robust to the fluctuating Rand/US$ exchange rate and could accommodate a lower lobster survival rate. Results presented in this study indicate that rock lobster farming is a marginal commercial prospect based on current production performance and costs. Further research to develop effective puerulus collection techniques as well as to make lobster grow out technology more cost effective is required.

This study is concerned with description of larval stages of Pagurus granosimanus, P. hemphilli and P. hirsutiusculus. All three are found intertidally in Northern California. Descriptions are based on laboratory raised zoea and glaucothoe.

published_or_final_version / Biological Sciences / Master / Master of Philosophy

Título original: Biologia e ecologia de Macrobrachium amazonicum (Heller, 1862) (Decapoda : Palaemonidae) e sua importância em reservatórios neotropicais / Orientador: Fernando José Zara / Banca: Fernando Luis Medina Mantelatto / Banca: Rogerio Caetano da Costa / Banca: João Alberto Feribelli Pantaleão / Banca: Abner Carvalho Batista / Resumo: O camarão amazônico Macrobrachium amazonicum apresenta populações com grande plasticidade fenotípica e alta variabilidade morfológica e reprodutiva. Três fenótipos são registrados para a espécie, por meio da avaliação de sua história de vida, características morfológicas e reprodutivas, sendo eles: (a) animais anfídromos de grande porte, e (b) hololimnéticos de grande e (c) pequeno porte. Tais características permitem que estes animais ocupem diversos ambientes aquáticos no Brasil. Nos últimos anos, registros de M. amazonicum em ambientes dulciaquícolas interiores em diversas regiões brasileiras aumentaram significativamente, principalmente em reservatórios da Bacia do Paraná. Porém, são escassas as informações sobre aspectos bioecológicos e reprodutivos em tais ambientes, assim como faltam estudos abordando a morfo-histologia dos sistemas reprodutores da espécie. Além disso, a plasticidade fenotípica de populações de M. amazonicum ainda não é totalmente compreendida. Na presente tese, os padrões anátomo-histológico dos sistemas reprodutores foram analisados nos três fenótipos da espécie, além biologia e a ecologia das populações com diferentes fenótipos provenientes de reservatórios do sudeste brasileiro. Adicionalmente, descreve-se o primeiro registro da intersexualidade e de infecção por microsporídeos em M. amazonicum. Independentemente da história de vida e estratégia sexual adotada, todas as populações de camarão amazônico analisadas apresentam padrões anatômicos, histo... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The Amazon river shrimp Macrobrachium amazonicum exhibits populations with great phenotypic plasticity and high morphological and reproductive variability. Three phenotypes are recorded for the species, through the evaluation of their life history, morphological and reproductive characteristics, being: (a) large amphidromous, and (b) large and (c) small hololimnetic animals. These characteristics allow these animals to occupy diverse aquatic environments in Brazil. In recent years, M. amazonicum records have increased significantly in continental freshwater environments in Brazil, mainly in reservoirs inserted at the Paraná Basin. However, information on bioecological and reproductive aspects in such environments is scarce. Also, there were no studies evaluating the histomorphology of the reproductive systems in Amazon shrimp. In addition, the phenotypic plasticity of populations of M. amazonicum is not yet fully understood. In the present thesis the histoanatomic patterns of the reproductive systems were analyzed in three phenotypes of the species. As well, the biology and ecology of populations with different phenotypes were investigated in reservoirs of the southeastern Brazil. In addition, the first record of intersexuality and microsporidiosis in the species are presented here. Regardless of the life history and sexual strategy adopted, all populations of M. amazonicum analyzed present similar anatomical, histological, histochemical and ultrastructural patterns in their reproductive systems. However, females and males of the small populations tend to invest more energy in reproductive aspects when compared to large amphidromous and hololimnetic animals. Small females displace more energy to produce larger oocytes/eggs and lipid reserves for larvae, while males of this phenotype invest energy in sperm production and ... (Complete abstract click electronic access below) / Doutor