Um dos principais problemas relacionados aos estudos limnológicos realizados manualmente em laboratório consiste no grande esforço, tempo de análise e trabalho especializado necessário. Esses fatores limitam a quantidade de amostras possíveis de serem analisadas em um determinado estudo, já que recursos sejam eles reagentes, recursos financeiros ou tempo são limitados. No presente trabalho foi utilizado um sistema semi-automatizado de medidas de variáveis físicas e químicas da água. O sistema é composto por uma sonda multi-parâmetro (Horiba U-22) e um sistema de posicionamento global (GPS) acoplados a um micro-computador, que realizam medidas georeferenciadas em curtos intervalos de tempo, permitindo um rastreamento horizontal das características da água. Foi ainda desenvolvido um sistema semi-automático para coleta fracionada da comunidade planctônica por meio de bomba de sucção operada por bateria e filtro coletor com rede de plâncton de diferentes aberturas de malha. O material coletado foi fotografado por meio de sistema de aquisição digital de imagens (microscópio Zeiss equipado com câmera AxionCan). Neste trabalho foi produzido um software (Planktonscan) que a partir da análise das imagens capturadas permite produzir dados com estimativas das medidas e dimensões dos organismos, calcular biovolumes e, utilizando fatores de conversão, estimar os valores de biomassa. O software apresenta uma interface para identificação, calcula a densidade dos organismos e produz relatório gráfico com informações sobre os organismos individuais e sobre a comunidade. Os equipamentos e o software foram testados em análises limnológicas e amostragem de plâncton no reservatório do Monjolinho, São Carlos, SP, em dezembro de 2005. Os resultados obtidos foram comparados com os disponíveis na literatura e demonstraram a aplicabilidade do sistema. / A major problem associated with the study of planktonic communities lies on the difficulties of analyzing the collected material, a long time-consuming procedure. Biomass determination is also a step requiring great effort and is subjected to large errors. In the present work a semi-automated system for measuring physical and chemical variables in the water was developed. The system is made up by a flow-pump, a multi-parameter probe and a global positioning system coupled to a microcomputer that performs measurements at short time intervals, allowing a horizontal tracking of the water quality, in much shorter times than traditional methods. Another semi-automated device was developed for collecting separate plankton size fractions. It uses a battery operating suction-pump coupled to a filter with different mesh nets. The collected materials are then submitted to image computer acquisition (Axion Vision Zeiss System). Additionally, in this study a software was produced (Planktonscan), that taking the measures of individuals dimensions (length, width and height) calculates biovolume and using conversion factors calculate the biomass for each zooplankton organism identified in the sample. Both systems were tested, regarding the measurement of limnological variables and plankton sampling, in the Monjolinho Reservoir, SP. The performance was good, resulting in a larger number of points sampled (60) in a shorter sampling time (1 hour) than those usually required. The biomass results provided by Planktonscan software were compared to data from literature, obtained by the traditional gravimetric method for dry weight determination and also with data generated from the use of mathematical models (length dry-weight regressions) available. The results were expressed as species population densities, biomasses and size spectra, evidencing the applicability of the models here developed.

Submitted by Cássia Santos (cassia.bcufg@gmail.com) on 2015-10-27T13:26:49Z No. of bitstreams: 2 Tese - Vanessa Guimaraes Lopes - 2015.pdf: 9288152 bytes, checksum: 7a98610592071cbe6344b03ad8d07478 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Approved for entry into archive by Luciana Ferreira (lucgeral@gmail.com) on 2015-10-27T14:48:25Z (GMT) No. of bitstreams: 2 Tese - Vanessa Guimaraes Lopes - 2015.pdf: 9288152 bytes, checksum: 7a98610592071cbe6344b03ad8d07478 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) / Made available in DSpace on 2015-10-27T14:48:25Z (GMT). No. of bitstreams: 2 Tese - Vanessa Guimaraes Lopes - 2015.pdf: 9288152 bytes, checksum: 7a98610592071cbe6344b03ad8d07478 (MD5) license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Previous issue date: 2015-03-27 / Several studies have shown that spatial synchrony is a ubiquitous pattern, occurring in different regions, types of ecosystems and in different groups of organisms. Spatial synchrony has important implications for the persistence of populations. Another implication is the possibility of using local "sentinels" sites, assuming regionalized or synchronous dynamics over the whole area of interest. In this context, our work uses a long-term (8 years) data set to quantify the level of synchrony between local zooplankton populations in a tropical reservoir. We expect high synchrony due to high connectivity as well as due to the Moran effect. Population synchrony was negatively correlated with geographic distance. However, population synchrony declined more consistently with environmental distance and environmental synchrony than with geographic distance. Besides, our results suggested that main variables driving synchrony were those correlated with hydrological conditions. Geographic distance was more important for protozoans, while the population synchrony of the other zooplankton groups was strongly driven by environmental synchrony. Furthermore, we found a decrease of environmental synchrony with the increase of geographical distance between points. Our results suggest that the strength of the Moran’s effect may be underestimated when simple environmental distances are used. We suggest that further studies should allow for environmental synchrony instead of allowing only for environmental similarity. Finally, despite significant, population synchrony was not so high to justify a reduction in the number of sampling sites. / Diversos estudos têm demonstrado que a sincronia espacial é um padrão ubíquo, ocorrendo em diferentes regiões, tipos de ecossistemas e para diferentes grupos de organismos. A sincronia espacial apresenta implicações importantes para a persistência das populações. Outra implicação é a possibilidade de utilizar locais “sentinelas”, supondo dinâmicas regionalizadas ou sincrônicas, para toda a área de interesse. Nesse contexto, o presente trabalho utiliza um conjunto de dados de longa duração (8 anos) em um reservatório tropical para quantificar o nível de sincronia entre populações locais zooplanctônicas. Esperamos alta sincronia devido à alta conectividade, bem como devido ao efeito Moran. Contudo, nossos resultados mostraram declínio da sincronia populacional mais consistente com a distância ambiental e sincronia ambiental do que distância geográfica. Além disso, nossos resultados também sugerem que as principais variáveis direcionando a sincronia populacional foram aquelas mais relacionadas às variações hidrológicas. A distância geográfica foi mais importante para os protozoários, enquanto a sincronia populacional dos outros grupos do zooplâncton foi fortemente impulsionada pela sincronia ambiental. Além disso verificou-se o decaimento da sincronia ambiental com o aumento da distância geográfica entre os pontos. Nossos resultados sugerem que a força do efeito de Moran pode ser subestimada quando simples distâncias ambientais são utilizadas. Sugere-se que novos estudos devem incluir a sincronia ambiental em vez de utilizar apenas a similaridade ambiental entre os pontos. Finalmente, apesar de significativa, a sincronia população não foi tão alta para justificar uma redução do número de pontos de amostragem.

Made available in DSpace on 2015-09-25T12:19:07Z (GMT). No. of bitstreams: 1 Ana Maria Alves da Silva.pdf: 1086889 bytes, checksum: a6694c8372c40371c39baa73bf55c15c (MD5) Previous issue date: 2008-12-19 / Sem resumo

Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-05-15T20:39:20Z No. of bitstreams: 1 monalisadeoliveiranascimento.pdf: 941297 bytes, checksum: 0ab9b6d24b97368a8b471da73b2ddc50 (MD5) / Approved for entry into archive by Adriana Oliveira (adriana.oliveira@ufjf.edu.br) on 2017-05-17T16:13:19Z (GMT) No. of bitstreams: 1 monalisadeoliveiranascimento.pdf: 941297 bytes, checksum: 0ab9b6d24b97368a8b471da73b2ddc50 (MD5) / Made available in DSpace on 2017-05-17T16:13:19Z (GMT). No. of bitstreams: 1 monalisadeoliveiranascimento.pdf: 941297 bytes, checksum: 0ab9b6d24b97368a8b471da73b2ddc50 (MD5) Previous issue date: 2012-09-05 / Estudos sobre saturação de espécies buscam conhecer o papel relativo de fatores locais e regionais sobre a estruturação das comunidades. No caso de comunidades zooplanctônicas, os resultados encontrados são bastante divergentes, tornando necessário o preenchimento de certas lacunas. Uma destas está na comparação entre diferentes tipos de ambiente, como perenes e temporários, que apresentam comunidades com características bem distintas. Lagoas temporárias passam periodicamente por eventos de seca e, considerando organismos aquáticos, este é um dos mais fortes distúrbios experimentados, pois impõe severas restrições fisiológicas e comportamentais. Baseado nestes fatos, este estudo tem como hipótese principal que lagoas temporárias apresentam comunidades zooplanctônicas insaturadas, enquanto lagoas perenes apresentam comunidades zooplanctônicas saturadas. Para testá-la, foi realizado um experimento em mesocosmos onde as comunidades zooplanctônicas destes dois tipos de lagoas foram manipuladas, bem como o evento de dispersão. Os resultados indicam que ambas apresentam-se saturadas e que, portanto, fatores locais são predominantemente mais importantes do que a dispersão (fator regional) sobre a estruturação destas comunidades. Dentre estes fatores locais, os fatores abióticos atuam como filtros selecionadores de espécies e parecem ser mais importantes do que as interações bióticas com as comunidades residentes. / Many studies about species saturation try to find out the relative role of the local and regional factors on the communities structure. Regarding to zooplankton communities, the results obtained are very divergent requiring the filling of certain gaps. One of these gaps is on the comparison between different types of environments, like perennial and temporary which have communities with very different features. Temporary ponds are periodically affected by drought events and, considering the aquatic organisms, this is one of the strongest disturbs that they experienced because it imposes physiological and behavioral restrictions. Based on these facts, the principal hypothesis of this study is that temporary ponds have unsaturated zooplankton communities while permanent ponds have saturated zooplankton communities. To test it, an experiment was made in mesocosms where the communities of both ponds were manipulated as well as the dispersion event. The results indicate that both communities are saturated and therefore local factors are predominantly more important than the dispersion (regional factor) on the structuring of these communities. Among these local factors, the abiotic factors act as species selectors filters and seems to be more relevant than the biotic interactions with the resident species.

Au cours de cette étude, le cycle de vie de Paracartia grani, un copépode calanoïde appartenant à la famille des Acartiidae, a été déterminé dans la lagune de Thau. En effet, ce copépode aurait une implication dans le cycle de vie du parasite Marteilia refringens, affectant les productions de bivalves. Un suivi bimensuel de la communauté mésozooplanctonique effectué sur deux ans à une station fixe dans la lagune a permis de déterminer que P. grani est l'espèce d'Acartiidae dominante en été. Son cycle de vie se compose de deux phases : une phase pélagique d'avril à janvier, et une phase benthique de février à début avril durant laquelle l'espèce subsiste dans le sédiment sous la forme d'œufs de diapause. L'analyse de la structure de la population (spectre de taille, contribution des stades de développement et sexe ratio) a permis de déterminer que 9 générations se succédaient pendant l'année. L'étude de l'influence de 3 paramètres environnementaux (température, salinité et concentration en chlorophylle a) sur la dynamique de ponte de l'espèce a révélé que la production d'œufs de P. grani était principalement régie par la température et que l'augmentation rapide de celle-ci au printemps permettait de déclencher l'éclosion des œufs de diapause. Le second objectif de cette étude s'est attaché à décrire la dynamique du parasite M. refringens chez P. grani et les bivalves Mytilus galloprovincialis et Ruditapes decussatus dans la lagune de Thau. Des analyses en histologie et hybridation in situ ont permis de décrire les différentes formes du parasite chez ces 3 espèces. La recherche de M. refringens par PCR chez les copépodites de P. grani a révélé la présence d'ADN de parasite de juin à novembre, période à laquelle de nouvelles moules apparaissent infectées. Les expériences de mesure de l'efficacité de rétention des différents stades de développement de P. grani par la moule ont permis de montrer que tous les stades de développement peuvent être impliqués dans le cycle de vie de M. refringens, en particulier les œufs du copépode qui ont par ailleurs présentés des résultats positifs en PCR. Notre étude a ainsi permis de préciser les interactions entre copépode, parasite et moules mais n'a pas permis d'élucider complètement le cycle de Marteilia refringens. Des questions restent posées concernant notamment les voies de transmission du parasite du copépode vers les moules et concernant l'impact potentiel du parasite sur le copépode lui-même. / In this study, the life cycle of Paracartia grani, a calanoid copepod belonging to the Acartiidae family was determined in Thau lagoon. Indeed, the copepod involvement in the life cycle of the parasite Marteilia refringens affecting the bivalves production is suspected. Mesozooplanktonic community was monitored twice a month over two years at a fixed station in the lagoon. Sampling has identified P. grani as the acartiid dominant species in summer. From April to January, the copepod is found in the water column while from February to early April it remains in the sediment as diapausing eggs. The analysis of the population structure (size spectrum, contribution of developmental stages and sex ratio) has revealed that there are 9 generations per year. The study of the influence of three environmental parameters (temperature, salinity and chlorophyll a concentration) on the dynamic nesting species indicated that P. grani egg production was mainly governed by temperature and its rapid increase in spring could trigger the hatching of diapause eggs.The second objective of this study aimed to describe the dynamics of the parasite M. refringens in P. grani, and in the bivalves Mytilus galloprovincialis and Ruditapes decussatus in the Thau lagoon. Histological and in situ hybridization analysis allowed describing the different forms of the parasite in these three species. Research of M. refringens by PCR in P. grani copepodites revealed that the parasite DNA presence in the copepod from June to November, when new mussels appeared infected. Experiments to measure the retention efficiency of the different stages of development of P. grani by mussels have shown that all developmental stages could be involved in M. refringens life cycle, especially copepod eggs that have also shown positive results by PCR. Our study has allowed clarifying interaction between copepods, parasites and mussels but not elucidate completely M. refringens life cycle. Questions remain especially regarding way of transmission of parasite from copepods to mussels and the potential impact of the parasite on the copepod itself.

Les estuaires sont des systèmes hautement dynamiques où interagissent des processus biogéochimiques complexes qui influent sur le devenir de la matière organique et non organique. La confrontation des eaux fluviales et marines induit des changements rapides des principaux facteurs structurant la distribution des organismes vivants et gouvernant la spéciation de certains éléments traces entre phase particulaire et dissoute, ex : gradient de salinité, teneurs en matières en suspension (MES). Ce travail vise à étudier l’estuaire de la Charente, principal fleuve influançant le bassin de Marennes-Oléron (première zone ostreicole française) afin (i) de caractériser la structure de la communauté zooplanctonique en relation avec les paramètres environnementaux, (ii) le fonctionnement de la base du réseau trophique de l’estuaire (identification des sources de matière organique exploitée par les organismes zooplanctoniques et suprabenthiques) et (iii) d’établir un état de contamination par les métaux des compartiments biotiques. L’estuaire de la Charente se distingue par des concentrations en MES extrêmement élevées, présentant néanmoins une contribution importante de la matière organique (efflorescence phytoplanctonique printanière en zone mésohaline et production microphytobenthique). La zone de turbidité maximale semble correspondre à un écotone qui contrôle les flux de matière organique et la distribution des organismes. Le mélange physique des particules issues des systèmes dulcicoles et marins adjacents à l’estuaire avec cette forte charge de matériel resuspendu conduit à une homogénéisation des signatures isotopiques et métalliques particulaires en été et automne le long du gradient de salinité. Les quatre assemblages zooplanctoniques identifiés sont structurés spatialement par la salinité et la concentration en MES et temporellement par les variations de température et de débit fluvial. Malgré la dominance quantitative du matériel détritique au sein du pool de matière organique particulaire (MOP), il semble que les 5 taxons planctoniques ou suprabenthiques dominants étudiés (Eurytemora affinis, Acartia spp., Daphnia spp., Neomysis integer, Mesopodopsis slabberi) présentent une sélectivité importante vis-à-vis de sources primaires distinctes. Cette succession spatio-temporelle d’espèces sélectives conduit à une multiplication des flux trophiques et semble ainsi optimiser à l’échelle annuelle l’exploitation de la MOP disponible. Les concentrations en Cd, Cu, Hg, Pb, V et Zn ont par ailleurs été mesurées dans près de 40 taxons estuariens (zooplancton, benthos, poissons). Malgré des concentrations en métaux dissous et particulaires plus faibles que dans les grands estuaires européens subissant une pression anthropique importante (Seine, Gironde), les niveaux de contamination mesurés dans les différents compartiments biotiques semblent globalement équivalents. Les évènements brefs (crue hivernale, efflorescence phytoplanctonique printanière) altèrent toutefois fortement ce schéma général en modifiant les sources primaires de matière organique disponibles et les concentrations métalliques particulaires (Cd notamment). / Estuaries are highly dynamic systems where complex biogeochemical greatly affect the fate of organic and non-organic matter. The physical mixing of freshwater and saltwater leads to high variability in the main drivers controlling organisms distribution and trace metals partitioning between the particulate and dissolved phases: eg. salinity gradient, suspended particulate matter concentration (SPM). This work aims thus at studying the Charente estuary, which is the main river discharging into the Marennes-Oléron Bay (first oyster producing area in France) in order to (i) characterize the zooplankton community structure and relate it to the main environmental parameters, (ii) identify the main organic matter sources contributing to the functioning of the planktonic food web and (iii) to characterize contamination of the biological compartment of this estuary. Although being one of the most turbid estuaries in Europe, the Charente estuary displays quite high organic matter contribution, especially through a spring phytoplankton bloom in the mesohaline area and microphytobenthic production. The maximum turbidity zone (MTZ) displays some ecotonal characteristics, controlling both organic matter fluxes and organisms distribution. The physical mixing of terrestrially and marine derived particles within the high load of resuspended estuarine particles leads to quite homogeneous isotopic and metallic signatures in particles all along the salinity gradient during summer and autumn. Salinity and SPM concentration significantly controls the spatial distribution of the four zooplankton assemblages identified while temperature and river discharge controls their temporal variations. Despite the quantitative dominance of terrestrially derived detrital organic matter, the five dominant planktonic and suprabenthic taxa studied (Eurytemora affinis, Acartia spp., Daphnia spp., Neomysis integer, Mesopodopsis slabberi) display strong selectivity toward different organic matter sources. At the annual scale, the exploitation of the available stock of organic matter seems optimized by this spatio-temporal succession of selective species that leads to multiple trophic pathways. In addition, the concentrations of Cd, Cu, Hg, Pb, V and Zn were measured in nearly 40 estuarine taxa (zooplankton, benthos, fishes). Although particulate and dissolved metal concentrations were somewhat low as compared to those measured in highly impacted European estuaries (Seine, Gironde), the contamination levels recorded in these biotic compartments were of the same order of magnitude. Moreover, brief events such as high water levels and phytoplankton blooms greatly affect this overall pattern by modifying the available organic matter sources and particulate trace metals concentrations (especially Cd).

Conselho Nacional de Desenvolvimento Científico e Tecnológico / The objective of this experiment was to determine the lethal concentration (LC50;96h) of azimsulfuron (A) and metsulfuron-methyl (M) herbicides and carbofuran (C) insecticide for common (Cyprinus carpio), grass (Ctenopharyngodon idella )and big head (Aristichthys nobilis) carps fingerlings, and the effect of these pesticides on the cholinergics response in fish; to quantify the survival and growth of common, grass and bighead carps fingerlings in rice fields, that were subjected to pesticides; to estimate the effect of the pesticides in the zooplankton community present in the water of irrigation rice and quantify the rice farming production in rice-fish culture. The experiments were divided in experiment 1 (LC50;96h determination for fish), fulfilled in laboratory and experiment 2 (exposure of carps and zooplankton in rice fields), carried in lowland area of Departament of Fitotecnia (UFSM). In experiment 1 the carps (10 fingerlings/replicate) were exposed to the pesticides for 96 h in a entirely randomized experiment (three replicates), evaluating the survival and swimming behaviors of the fishes. Surviving fishes were frozen and brain and muscle removed for acetilcholinesterase enzyme analysis (AChE). The experiment 2, carried in growing seasons 2003/04 and 2004/05 in a randomized complete block experiment with four replicates (experimental units 48 m2- 8mx6m), started with rice seeding in pre-germinate system, and pesticides application with eight treatments: T1- A+fish; T2- M+ fish; T3- C+ fish; T4- A+M+C+ fish; T5- A+M+C (without fish); T6- A+M+ fish; T7- control 1 (only rice); T8- control 2 (rice+ fish). After eight days of the pesticides application, fish were placed in refuge area, where remained during the whole rice culture until October. In this period, the zooplankton collection was fulfilled 17 days before pesticides application up to 75th days after this application. Results allon to 14 conclude that LC50;96h carbofuran was 1.81 mg/L for common carp, 2.71 mg/L for grass carp and 2.37 mg/L for bighead carp. This study showed that doses of carbofuran near that applied in rice culture (0.75 mg/L) provoked mortality and affected behavior and AChE activity in the studied species (Cyprinus carpio, Ctenopharyngodon idella, and Aristichthys nobilis), indicating that the use of this insecticide is not recommended for rice-fish culture system. For experiment 2, the application of pesticides (carbofuran, azimsulfuron and metsulfuron-methyl) in rice farming did not affect survival of common, grass and bighead carps when fingerlings are put eight days after pesticides application. At this moment, waterborne carbofuran concentrations were 0.025 and 0.144 mg/L (years 1 and 2 respectively), and these levels can be considered of low toxicity for fish. Rice productivity was not influenced by these pesticides when the continuous flooding management was used after pre-germinated rice sow. The rice productivity in year 1 was 4151 kg ha-1, and in year 2, 5643 kg ha-1. Carbofuran application provoked negative effects in zooplankton community of the rice-fish culture, for Cladocers group. Copepods (adults and nauplius), and Rotifers were slighly affected by carbofuran application. Adults Copepods were affected by the presence of fish in the treatments. / Este trabalho tem por objetivos determinar a concentração letal mediana (CL50;96h) dos herbicidas azimsulfuron (A) e metsulfuron-metílico (M) e do inseticida carbofuran (C) para alevinos de carpa húngara (Cyprinus carpio), carpa capim (Ctenopharyngodon idella) e carpa cabeça grande (Aristichthys nobilis), bem como o efeito destes sobre as respostas colinérgicas dos peixes; quantificar a sobrevivência e o crescimento de alevinos de carpas húngara, capim e cabeça grande na lavoura de arroz, expostos aos agroquímicos, avaliar o efeito dos agroquímicos na comunidade zooplanctônica presente em água de irrigação do arroz e quantificar a produção de arroz em rizipiscicultura. Os experimentos foram divididos em experimento 1 (determinação da CL50;96h para peixes), realizado em laboratório, e experimento 2 (exposição das carpas e zooplâncton na lavoura arrozeira), conduzido em área de várzea do Departamento de Fitotecnia da UFSM. No experimento 1, as carpas (10 alevinos/repetição) foram expostas aos agroquímicos por 96 h, em delineamento experimental inteiramente casualizado (três repetições), avaliando-se a sobrevivência e comportamento natatório dos peixes. Os peixes sobreviventes foram congelados e após foram retirados cérebro e músculo para realização de análise da enzima acetilcolinesterase (AChE). O experimento 2, realizado nas safras agrícolas 2003/04 e 2004/05, em delineamento experimental de blocos ao acaso, com quatro repetições (unidades experimentais que possuíam 48 m2 - 8m x 6m), iniciou com a semeadura do arroz no sistema pré-germinado, e posterior aplicação dos agroquímicos, com oito tratamentos: T1- A+peixe; 12 T2- M+peixe; T3- C+peixe; T4- A+M+C+peixe; T5- A+M+C (sem peixe); T6- A+M+peixe; T7- controle 1 (somente arroz); T8- controle 2 (arroz+peixe). Oito dias após a aplicação dos agroquímicos foram colocados os peixes na área do refúgio, onde permaneceram durante toda a cultura do arroz até outubro seguinte. Nesse período, foi realizada a coleta de zooplâncton, 17 dias antes da aplicação dos agroquímicos, seguindo até o 75° dia após aplicação destes. Com os resultados obtidos pode-se concluir que a CL50;96h do carbofuran foi: carpa húngara: 1,81 mg/L, carpa capim: 2,71 mg/L e carpa cabeça grande: 2,37 mg/L. Este estudo demonstrou que doses de carbofuran próximas à aplicada para a cultura do arroz (0,75 mg/L) provocam mortalidade e afetam o comportamento e a atividade da acetilcolinesterase nas espécies de peixes estudadas (Cyprinus carpio, Ctenopharyngodon idella e Aristichthys nobilis), indicando que a utilização deste inseticida não é recomendada para o sistema de rizipiscicultura. Para o experimento 2, a aplicação dos agroquímicos (carbofuran, azimsulfuron e metsulfuron-metílico) na lavoura arrozeira não afetou a sobrevivência de carpas húngara, capim e cabeça grande, quando os alevinos são colocados oito dias após sua aplicação e as concentrações de carbofuran na água eram de 0,025 e 0,144 mg/L, nos anos experimentais 1 e 2, respectivamente, já com níveis que podem ser considerados pouco tóxicos para os peixes. Já, a produtividade do arroz não foi influenciada pelos agroquímicos, quando utiliza-se o manejo adequado de lâmina contínua a partir da semeadura pré-germinada do arroz. A produtividade média do arroz irrigado no ano 1 foi de 4151 kg ha-1 e no ano 2 de 5643 kg ha-1. A aplicação do agroquímico carbofuran provocou efeitos negativos na comunidade zooplanctônica da rizipiscicultura, para o grupo Cladocera. Copepoda (adultos e nauplios) e Rotifera foram pouco afetados pela aplicação do carbofuran. Copepoda adultos foram afetados pela entrada de peixes na área.

The dynamics of zooplankton and phytoplankton growth and interactions play a significant role in water quality (e.g., pH and dissolved oxygen [DO]) and the available food supply for higher order organisms in the San Joaquin River Delta. Algae have been shown to significantly impact DO concentrations in the Deep Water Ship Channel (DWSC) of the San Joaquin River (SJR) estuary. Zooplankton grazing is one of the important mechanisms that influence the fate and spatial distribution of algae, and therefore, may contribute to DO deficits that adversely impact aquatic habitat and salmonid migration in the SJR estuary. Numerical water quality models developed to simulate and predict dissolved oxygen in the SJR rely on mathematical algorithms that link chemical and biological mechanisms. Due to the complexity of natural systems, calibrating these models is challenging and often requires independent investigations to estimate input parameters, such as zooplankton grazing and algal growth rates. This investigation explored the applicability of three methods to quantify the rates that zooplankton graze on algae populations in the SJR. Zooplankton grazing studies were performed in the DWSC of the SJR from June 2012 through July 2013. Light and dark bottle microcosm studies using the dilution method, the food-removal method, and the grazer concentration method were tested. A modified microcosm approach similar to the grazer concentration method was developed that yielded changes in chlorophyll a concentrations that were sufficient to separate zooplankton grazing from algal growth and respiration. Microcosms contained zooplankton concentrations that were up to 30 times higher than natural, background levels. Zooplankton grazing rates were consistent in both magnitude and variability with literature values reported for other waters, ranging from 0.295-3.404-m 3 gC -1 d -1 and 0.006-1.413-m 3 gC -1 d -1 for light and dark bottle microcosms, respectively.

No description available.

Non-native species and climate change pose serious threats to global biodiversity. However, the roles of climate, dispersal, and competition are difficult to disentangle in heterogeneous landscapes. We combine empirical data and theory to examine how these forces influence the spread of non-native species in Lake Baikal. We analyze the potential for Daphnia longispina to establish in Lake Baikal, potentially threatening an endemic, cryophillic copepod Epischurella baikalensis. We collected field samples to establish current community composition and compared them to model predictions informed by flow rates, present-day temperatures, and temperature projections. Our data and model agree that expansion is currently limited by dispersal. However, projected increases in temperature reverse this effect, allowing D. longispina to establish in Lake Baikal’s main basin. A strong negative impact emerges from the interaction between climate change and dispersal, outweighing their independent effects. Climate, dispersal, and competition have complex, interactive effects on expansion with important implications for global biodiversity.