Submitted by Maria Medeiros (maria.dilva1@ufcg.edu.br) on 2018-10-10T12:20:07Z No. of bitstreams: 1 LÁZARO RAMON DOS SANTOS ANDRADE - DISSERTAÇÃO (PPGRN) 2017.pdf: 2310709 bytes, checksum: 80378a5df11fa09ac7d1f0ac8d3f2b71 (MD5) / Made available in DSpace on 2018-10-10T12:20:07Z (GMT). No. of bitstreams: 1 LÁZARO RAMON DOS SANTOS ANDRADE - DISSERTAÇÃO (PPGRN) 2017.pdf: 2310709 bytes, checksum: 80378a5df11fa09ac7d1f0ac8d3f2b71 (MD5) Previous issue date: 2017-02-21 / Capes / A cidade de Campina Grande-PB vem sofrendo com a grande estiagem que assola a região Nordeste, diante disto a população vem desenvolvendo alternativas que para mitigar a crise hídrica. A utilização de águas residuárias na agricultura é uma prática que vem ganhando espaço nos últimos anos, no entanto estudos que comprovem sua qualidade devem ser efetuados, bem como a aplicação de técnicas de tratamento que contribuam para a preservação do meio ambiente e da qualidade de vida da população. A Universidade Federal de Campina Grande (UFCG) utiliza a água de duas lagoas contendo águas residuárias para irrigação das áreas verdes do campus. Diante da falta de tratamento dessas águas, o presente trabalho objetivou avaliar a qualidade dessas águas superficiais do campus sede da UFCG, para fins de reuso na irrigação de áreas verdes. A pesquisa foi realizada no ano de 2016, entre os meses de março a outubro, na qual foi avaliada a qualidade das águas por meio de uma sonda multiparâmetros, análises físico-químicas e microbiológicas. Os resultados foram comparados aos valores estabelecidos pela Resolução no 357 de 2005 do Conselho Nacional do Meio Ambiente (CONAMA), bem como utilizados para calcular o Índice de Estado Trófico (IET) e Índice de Qualidade da Água (IQA). O IQA da lagoa 1 classificou-se entre ruim e péssimo e o IQA da lagoa 2 foi classificado como péssimo em todos os meses de estudo. Com relação ao grau de trofia da lagoa 1, o IET variou entre Mesotrófico e Eutrófico nos seis primeiros meses, passando a Supereutrófico nos dois últimos meses. A lagoa 2 apresentou melhor IET no mês de março, de modo que os demais meses variaram entre Supereutrófico e Hipereutrófico. Constatou-se que a água da lagoa 2 apresentou qualidade inferior em relação a lagoa 1, em detrimento do canal que liga as duas lagoas e que recebe efluentes de pontos adjacentes do campus. Outro fator relevante para esses resultados é a presença de aves que eliminam seus excrementos na água além da entrada de efluentes advindos do bloco CA e do quiosque na margem da lagoa 2. Constatou-se que a utilização dessas águas sem tratamento pode acarretar danos ao solo, às plantas e causar doenças aos funcionários que operam os sistemas de irrigação, assim como as pessoas que utilizam o campo de futebol, bem como as áreas verdes para descanso ou lazer. Sendo assim se faz necessário a implantação de um sistema de tratamento de efluente que possa reduzir a carga poluidora dessas águas. / The city of Campina Grande-PB has been suffering from a prolonged drought common to the Northeast, which has necessitated developing alternative strategies to mitigate the water crisis. The use of wastewater in agriculture is a practice that has been gaining ground in recent years, however studies that prove its quality must be carried out, as well as the application of treatment techniques that contribute to the preservation of the environment and quality of life of the population. The Federal University of Campina Grande (UFCG) at its principal campus uses water from two small lakes contaminated with wastewater to irrigate the green areas of the campus. In view of the lack of treatment of these waters, this study aimed to evaluate the quality of this surface water used on the campus. The research was carried out between March and October 2016, and water quality was determined by means of a multiparameter submersible probe, plus additional physical-chemical and microbiological analyzes. The results obtained were compared to the values established by Resolution No. 357 of 2005 of the National Environment Council (CONAMA), for surface water quality and were used to calculate the Trophic State Index (EIT) and Water Quality Index (IQA). The IQA of Lake 1 ranged from poor to very poor and the IQA for Lake 2 was classified as poor in all months of study. In relation to the trophic level of Lake 1, the EIT varied between mesotrophic and Eutrophic during the first six months, passing to super eutrophic in the last two months of the study. Lake 2 presented a better EIT in the month of March, but for the other months, it varied between super eutrophic and Hypereutrophic. The water of lagoon 2 presented inferior quality in relation to lagoon 1, and this was due to the channel connecting the two lakes receiving additional effluents from adjacent points of the campus. Another additional factor that maybe relevant to these results on water quality was the contamination of the water with excrement from a large bird population and the entrance of effluents from the CA block and a cafe located at the margin of lake 2. From the results of this study it was concluded that the use of these waters without treatment represent a threat to soil quality, may damage existing vegetation and are a risk to public health, principally to the employees operating the irrigation systems, as well as to people who use the soccer field, and the green areas for rest or leisure. Therefore, it is necessary to implement an effluent treatment system that reduces the polluting load of these waters.

Changes in trophic status are often related to increases or decreases in the allocthonous inputs of nutrients from changes in land use and management practices. Lake and reservoir managers are continually faced with the questions of what to monitor, how to monitor it, and how much change is necessary to be considered significant. This study is a compilation of four manuscripts, addressing one of these questions, using data from six reservoirs in Texas.

Through a myriad of practices, anthropogenic land and water use has caused the localized extirpation or complete elimination of many native fishes throughout North America. Specifically, native salmonids have seen substantial declines in population sizes and geographic distributions due to a number of factors, including habitat loss or degradation, overharvest, or the introduction of non-native competitors and predators. Among those affected, the 14 subspecies of cutthroat trout found across western North America have been subject to two extinctions and five listings as Threatened as per the Endangered Species Act. Lahontan cutthroat trout Oncorhynchus clarkii henshawi have experienced marked reductions throughout their native range in the western Great Basin, U.S. In Pyramid Lake, Nevada, where they were once locally extirpated due to overfishing, water loss, and degraded spawning habitat, Lahontan cutthroat trout have been successfully stocked and managed, though they do not routinely reach their pre-extirpation sizes. With little research to determine the factors influencing Lahontan cutthroat trout in Pyramid Lake, I used a suite of modeling tools and empirical data to elucidate the influence of the current surrounding environment on Lahontan cutthroat trout in Pyramid Lake. To identify important food web interactions that may affect the availability of food to Lahontan cutthroat trout, I used diet composition and stable isotope analyses of carbon and nitrogen to understand dietary trends. Large Lahontan cutthroat trout (>400 mm TL), along with non-native Sacramento perch Ambloplites interruptus, relied most heavily on fish prey, yet neither species showed signs of cannibalism or preying on the other species. Diet composition and stable isotope analyses also indicated that Lahontan cutthroat trout rely mostly on tui chub Gila bicolor and other fish for food. I also used results from bioenergetic and hydroacoustic analyses to compare the number of tui chub consumed by trout to the number of tui chub in the lake, during the time of this study. Results from these analyses suggest that trout consume well below the number of tui chub available in the lake, indicating that trout are not limited by the availability of tui chub. Lastly, I used a number of biotic and abiotic predictors to determine which factors influence the distribution, and subsequently abundance, of trout in Pyramid Lake and found that biotic factors were very weak predictors of trout distribution, further indicating that trout are not limited by food resources in Pyramid Lake.

京都大学 / 新制・課程博士 / 博士(理学) / 甲第24454号 / 理博第4953号 / 新制||理||1707(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 中野 伸一, 教授 木庭 啓介, 教授 中務 真人 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

Earth's climate is prone to natural and episodic cycles. The most recent period of climate change, the only one to be caused by humans, is significantly affecting species composition and landscapes. Northern expansion of the Boreal Forest in Canada is one of the expected outcomes, and tree line migration northward is one of the anticipated changes. Previous studies have found that many human activities like agriculture, grazing, and pastoralism can significantly affect tree line movement. Improving our ability to examine past tree line dynamics can be achieved using archival records in lake sediments. In this study, we focused on three sediment biomarkers that may be related to the presence of trees in a lake's catchment: n-alkanes, lignin-derived phenols, and stable isotopes of carbon. We examined the composition of these markers in sediment from 19 lakes in Saskatchewan spanning 4 ecoregions, from Prairie Grassland to Boreal Plain, to determine the biomarker signature for lakes in each ecoregion and relating them to land cover (trees vs herbaceous plants) in the catchments of each lake. The results showed that n-alkane composition was significantly correlated to the proportion of trees to herbaceous plants in a lake's catchment, raising the possibility that these can be used to infer the presence of trees in sediment records. The C/N ratio and δ¹³C were not effective in distinguishing ecoregions or land cover composition, likely due to algal production in the lake and agricultural activities in the surrounding farmland, while lignin-derived phenols appeared to be affected by unknown factors.

Submitted by Erika Demachki (erikademachki@gmail.com) on 2015-01-16T17:09:40Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Susy Ferreira Oliveira Cordeiro - 2013.pdf: 4372840 bytes, checksum: 148e8aba2f91f518e6d702f1ac0ab3c7 (MD5) / Approved for entry into archive by Erika Demachki (erikademachki@gmail.com) on 2015-01-16T17:34:56Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Susy Ferreira Oliveira Cordeiro - 2013.pdf: 4372840 bytes, checksum: 148e8aba2f91f518e6d702f1ac0ab3c7 (MD5) / Made available in DSpace on 2015-01-16T17:34:56Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) Dissertação - Susy Ferreira Oliveira Cordeiro - 2013.pdf: 4372840 bytes, checksum: 148e8aba2f91f518e6d702f1ac0ab3c7 (MD5) Previous issue date: 2013-10-25 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The increasing energy demand made there was a use of part of the water potential energy of Brazil, and in this context the use of the basin of Rio Claro, one of the main tributaries of the Rio Parnaíba basin, located in the southern state of Goiás also framed, and the target of this study is the reservoir of the hydroelectric Barra dos Coqueiros, located in the middle portion of the basin. The enrichment of water with nutrients is called eutrophication and this is measured by calculating the Trophic State Index (TSI). The goal of this research is to evaluate and classify TSI reservoir of the hydroelectric Barra dos Coqueiros by proposed method of Carlson (1977) and modified by Toledo (1984) and Lamparelli (2010) in two distinct periods, dry (July 2012) and rainy (January 2013). The variables analyzed are: phosphorus, chlorophyll a and Secchi depth transparency, which were applied to the equations proposed by each method. The total proposed EIT in Carlson (1977) and Toledo (1983) had little variation was oligotrophic and mesotrophic dominance in eutrophic and mesotrophic dry period during the rainy season. Already in porposta of Lamparelli (2004) all classes were diagnosed in both periods. In all variables and applied to the proposed EIT was higher in the rainy season than in the dry. / A crescente demanda energética fez com que houvesse um aproveitamento de parte do potencial hídrico energético do Brasil, e nesse contexto o aproveitamento da bacia do Rio Claro, um dos principais afluentes da bacia do rio Paranaíba, localizado na região sul do estado de Goiás também se enquadrou, e é alvo deste estudo o reservatório da usina hidrelétrica Barra dos Coqueiros, situado na porção média desta bacia. O enriquecimento da água em nutrientes é denominado eutrofização, e a medida desta são através do calculo do Índice do Estado Trófico (IET).O objetivo da presente pesquisa, é avaliar e classificar IET do reservatório da Usina Hidrelétrica Barra dos Coqueiros através do metódo proposto de Carlson (1977), e modificado por Toledo (1984) e Lamparelli (2010) em dois períodos distintos, seco (julho de 2012) e chuvoso (janeiro de 2013). As variáveis analisadas são: fósforo, clorofila a e profundidade da transparência de Secchi, as quais foram aplicadas nas equações propostas por cada um dos métodos. O IET da variável clorofila a, predominou duas classes em todas as propostas nos dois períodos analisados, que foi oligotrófico e mesotrófico. O IET total na proposta de Carlson (1977) e Toledo (1983) teve pouca variação teve predomínio oligotrófico e mesotrófico no período seco e eutrófico e mesotrófico no período chuvoso. Já na porposta de Lamparelli (2004) todas as classes foram diagnosticadas nos dois períodos. Em todas as variáveis analisadas e aplicadas às propostas o IET foi mais elevado no período chuvoso que no período seco.

Excessive nutrient loading of natural and artificial lakes has led, in some systems, to plethoric algal and aquatic macrophyte growth which can result in aesthetic degradation and undesirable tastes and odors. It would be advantageous to have some indication of the potential trophic status of a reservoir before it is filled. An objective of this study was to assess the water quality and nutrient loading potential of the tributaries entering Ray Roberts Lake, a large reservoir located in north central Texas. Samples from a maximum of thirteen sites were collected on the Elm Fork, Trinity River, Isle duBois Creek, and five additional tributaries. Data were also collected during six storms, from atmospheric deposition collectors, and from soil-water microcosms. The relationship between watershed landuse and mean water nutrient concentrations was evaluated. Significant differences will exist between the two major arms of Ray Roberts Lake: Elm Fork, Trinity River and Isle duBois Creek. While the majority of the annual phosphorus and nitrogen load entering both tributaries is coming from overland flow, the proportion is higher in Isle duBois Creek. Point sources in the Elm Fork contribute a larger percentage of the bioavailable phosphorus, which is significantly greater than in Isle duBois Creek. The water quality of Isle duBois Creek, especially nitrogen, is affected to a greater degree by the landuses in its watershed. Predictive regression models made accurate estimations of stream nutrient concentrations in Isle duBois Creek. The entire reservoir, upon reaching equilibrium conditions, will be classified as a eutrophic lake. The Trinity arm, with a higher phosphorus load, will display a higher trophic status. The Isle duBois arm has a lower phosphorus load which will give it a lower trophic status. The long hydraulic residence time of the two arms of the reservoir will remove nutrients upstream of the main body, thus contributing to overall better water quality in the main body of the reservoir.

En raison de leur importante capacité de réponse aux changements environnementaux, les producteurs primaires sont depuis longtemps utilisés comme indicateurs biologiques de la qualité des milieux aquatiques. La Directive Cadre Européenne sur l’Eau (2000/60/CE) préconise ainsi l’utilisation du phytoplancton, du phytobenthos et des macrophytes afin de mesurer l’état écologique des écosystèmes lacustres. Dans cette étude, ces trois compartiments ont été utilisés pour déterminer l’état écologique de cinq lacs localisés dans la région Aquitaine (Sud-Ouest de la France), lacs ayant la particularité de présenter des niveaux trophiques différents. Les résultats ont montré qu’au niveau intra-lac la composition floristique dépend fortement des variables physiques dans la plupart des systèmes tandis qu’au niveau inter-lac celle-ci dépend du niveau trophique. Le phytoplancton s’est révélé être l’indicateur de qualité le plus performant et le seul utilisable dans les eaux ouvertes, et le plus précis dans les systèmes où les macrophytes submergés étaient absents. Cependant, dans les lacs humiques, les assemblages phytoplanctoniques semblent répondre davantage à la turbidité et aux brassages fréquents de la colonne d’eau qu’aux nutriments. Dans de telles conditions, afin de mieux caractériser la qualité de l’eau, l’utilisation complémentaire du phytobenthos et des macrophytes se révèle plus pertinente. En conclusion, considérant les trois compartiments biologiques, la présente étude permet une approche complémentaire de l’état écologique des systèmes lacustres. Certaines des méthodes appliquées ici représentent un outil potentiel de détermination de la qualité de l’eau selon les exigences de la DCE, mais elles nécessitent d’être affinées pour une meilleure évaluation de l’état écologique des lacs français. Une attention particulière a été portée aux taxa exotiques observés dans ces lacs tempérés, et cet aspect doit être pris en considération lors de l’évaluation écologique. En effet, ces espèces sensiblement avantagées par les conséquences du changement climatique, peuvent altérer la structure et le fonctionnement des écosystèmes aquatiques en place, et aboutir à une perte de diversité. / Due to their important ability to respond to environmental changes, primary producers have been used for a long time as biological indicators of water quality. The Water Framework Directive (2000/60/EC) recommends the use of the phytoplankton, phytobenthos (diatoms) and macrophytes in the ecological status assessment of lakes. In this study, these three compartments have been used to determine the ecological status of five lakes located in the Aquitaine region (southwest of France) with different trophic status. The results showed that within lakes, the floristic composition in most of the systems strongly depends on physical parameters whereas among lakes it depends on the trophic status. The phytoplankton proved to be the most powerful indicator of quality in open-water areas as well as in systems where submerged macrophytes are absent. However, in the humic lakes, the phytoplankton assemblages seem to respond more to turbidity and mixing than to nutrient load. Under such conditions, water quality could be underestimated and the complementary use of phytobenthos and macrophytes appears more appropriated. In conclusion, considering the three biological elements, the present study allows a complementary approach of the ecological status of the lakes. Some of the methods applied here represent a potential tool for the assessment of the ecological status in the context of WFD, but they need to be refined to assess more properly the ecological status of French lakes. A special attention was paid to exotic taxa observed in these temperate lakes, and this aspect must be taken into account in the ecological assessment. Indeed, these species favoured by the consequences of the climate change, can modify the structure and functioning of the aquatic ecosystems, and lead to a loss of diversity.

Two years before impoundment, the trophic status of Lake Ray Roberts was predicted by applying the total phosphorus input into the Organization for Economic Cooperation and Development (OECD) eutrophication model. Predicted mean summer epilimnetic (MSE) chlorophyll a of Elm Fork arm, Isle duBois arm and Main Body were in the eutrophic category of the OECD model. Observed MSE chlorophyll a two years after impoundment of Elm Fork arm, Isle duBois and Main Body had not reached their predicted means and were at the mesotrophic-eutrophic boundary of the OECD model. Six years after impoundment, observed MSE chlorophyll a for Main Body, was closer to its predicted mean and in the eutrophic category of the OECD model. Six years after impoundment, Elm Fork arm was the most productive area of Lake Ray Roberts. Observed means of chlorophyll a, total phosphates, suspended solids and turbidity were often highest in the Elm Fork arm. Wastewater effluent from Gainesville and Valley View, TX, had an impact on productivity in Elm Fork arm.

Η παρούσα διδακτορική διατριβή εστιάστηκε στη μελέτη των σημαντικότερων οικολογικών και βιολογικών παραμέτρων του ζωοπλαγκτού των λιμνών Αμβρακίας, Λυσιμαχείας και Οζερός. Στόχος της μελέτης αυτής είναι η καλύτερη κατανόηση του οικολογικού ρόλου που διαδραματίζουν οι ζωοπλαγκτικές βιοκοινωνίες στα λιμναία οικοσυστήματα στην περιοχή της Δυτικής Ελλάδας, καθώς και η αποτύπωση της σημερινής κατάστασης στην οποία βρίσκονται. Πραγματοποιήθηκαν μηνιαίες δειγματοληψίες κατά την περίοδο Σεπτέμβριος 2006-Αύγουστος 2008 στη λίμνη Αμβρακία και αντίστοιχα κατά την περίοδο Ιούνιος 2009-Μάιος 2010 στις λίμνες Λυσιμαχεία και Οζερός. Σε κάθε λίμνη γινόταν συλλογή δειγμάτων ζωοπλαγκτού, in situ καταγραφή των βασικών φυσικοχημικών παραμέτρων των υδάτων και συλλογή δειγμάτων νερού για τον προσδιορισμό της συγκέντρωσης των κυριότερων θρεπτικών στοιχείων και της χλωροφύλλης-α. Η Αμβρακία είναι μια θειικού τύπου λίμνη με υψηλή αγωγιμότητα. Χαρακτηρίζεται ως θερμή μονομικτική και κατά την περίοδο της θερμοστρωμάτωσης στο υπολίμνιο παρατηρείται ανάπτυξη υποξικών/ανοξικών συνθηκών. Οι λίμνες Λυσιμαχεία και Οζερός δεν εμφάνισαν φαινόμενα θερμοστρωμάτωσης, διατηρούν ικανοποιητικά επίπεδα οξυγόνωσης στην υδάτινη στήλη τους και παρουσιάζουν αρκετά χαμηλές τιμές διαφάνειας. Σύμφωνα με τις τιμές του δείκτη τροφικότητας του Carlson, η λίμνη Αμβρακία χαρακτηρίζεται ως μεσότροφη, η λίμνη Οζερός ως μεσο-εύτροφη και η λίμνη Λυσιμαχεία ως εύτροφη. Στη λίμνη Αμβρακία αναγνωρίστηκαν συνολικά 33 ζωοπλαγκτικά taxa, στη λίμνη Λυσιμαχεία 36 και στη λίμνη Οζερός 25. Λαμβάνοντας υπ’ όψιν τις μέσες τιμές αφθονίας του ζωοπλαγκτού στις τρεις λίμνες, η Αμβρακία (83,6-442,7 ind/l) προσεγγίζει καλύτερα τα χαρακτηριστικά ζωοπλαγκτικών βιοκοινωνιών που συναντώνται σε μεσότροφα οικοσυστήματα, ενώ ο Οζερός (59,4-818 ind/l) και ιδιαίτερα η Λυσιμαχεία (147,9-4449,3 ind/l) σε εύτροφα. Η εποχική διακύμανση της συνολικής αφθονίας του ζωοπλαγκτού των λιμνών, χαρακτηρίζεται από τη χαμηλή αφθονία των ειδών κατά τη χειμερινή περίοδο και τη σταδιακή αύξησή τους κατά την εαρινή. Στη βαθιά λίμνη Αμβρακία, η συντριπτική πλειοψηφία του ζωοπλαγκτού βρέθηκε συγκεντρωμένη στο στρώμα των 0-20 m. Το θερμοκλινές φάνηκε να ασκεί σημαντική επίδραση στον κατακόρυφο διαχωρισμό ειδών και οντογενετικών σταδίων. Η διερεύνηση της επίδρασης των περιβαλλοντικών παραμέτρων στην αφθονία και διακύμανση του ζωοπλαγκτού των τριών λιμνών έδειξε πως ο κύριος παράγοντας που φαίνεται να επηρεάζει τα περισσότερα ζωοπλαγκτικά είδη είναι η θερμοκρασία. / The present PhD thesis focused on the study of the main ecological and biological aspects of the zooplankton community in lakes Amvrakia, Lysimachia and Ozeros. The aim of this study is the better understanding of zooplankton’s ecological role in lake ecosystems of Western Greece. For the investigation of the zooplankton community in lakes, zooplankton samples were collected on a monthly basis in Lake Amvrakia during the period September 2006-August 2008 and in lakes Lysimachia and Ozeros during the period June 2009-May 2010. Additionally, for the assessment of water quality in lakes, water samplings were conducted at the same period in order to estimate the concentration of nutrients and chlorophyll-a, while the water’s basic physicochemical parameters were recorded in situ. Lake Amvrakia, which belongs to the sulphate type, exhibits high conductivity values. The lake is characterized as a warm monomictic lake. The main characteristic in the vertical axis was the depletion of oxygen in the deeper hypolimnion, where anoxic conditions prevail, especially at the end of the stratification period. Lakes Lysimachia and Ozeros maintained satisfactory levels of oxygenation in their water column and no thermal stratification was observed. Both lakes exhibited low transparency values. According to Carlson's Trophic State Index (TSI), Lake Amvrakia is characterized as mesotrophic, Lake Ozeros as meso-eutrophic and Lake Lysimachia as eutrophic. The zooplankton sampling in Lake Amvrakia revealed 33 zooplankton taxa, in Lake Lysimachia 36 and in Lake Ozeros 25. Considering the mean integrated abundance of the total zooplankton in the three lakes, Amvrakia (83.6-442.7 ind/l) exhibited the main characteristics of a mesotrophic ecosystem, while Ozeros (59.4-818 ind/l) and especially Lysimachia (147.9-4449.3 ind/l) of eutrophic lakes. The seasonal variation of the total abundance of zooplankton of lakes characterized by low species abundance in winter and a gradually increase during the spring period. The investigation of the zooplankton vertical distribution in the deep lake Amvrakia showed that the vast majority of species was concentrated in the layer of 0-20 m. The development of the thermocline layer had a significant effect on the vertical separation between species, as well as between ontogenetic stages. The water temperature seemed to have the most important influence on the temporal variation of most of the zooplankton taxa in lakes Amvrakia, Lysimachia and Ozeros.