O Reservatório do Lobo, inserido no APA de Corumbataí, Município de Itirapina, faz parte do sistema Jacaré Guaçú. Este sistema, nas últimas décadas, tem sofrido impactos antrópicos significativos. Apesar deste fato, o trabalho desenvolvido (coletas mensais em nove estações no Reservatório do Lobo), com coleta de dados a respeito das variáveis físicas, químicas e biológicas, entre os meses de junho de 1999 a maio de 2000, demonstrou que este sistema ainda apresenta uma comunidade fitoplanctônica semelhante à observada em trabalhos anteriores. As mudanças nesta comunidade estão ligadas às funções de forças físicas que atuam no sistema, principalmente a temperatura e aos regimes hidrológicos. O reservatório pôde ser caracterizado em dois compartimentos: o inferior (mais profundo, com a coluna d\'água mais homogênea) e o superior (entrada dos principais afluentes, com bancos de macrófitas). A Bacillariophyceae Aulacoseira distans predominou nos três primeiros meses (junho a agosto de 1999), favorecida pela transparência e mistura da coluna d\'água. A espécie Aphanocapsa delicatissima (Cyanophyceae), nos meses posteriores (setembro a dezembro de 1999) substituiu em densidade aquela espécie, devido ao aumento da temperatura na coluna d\'água, às estratificações e à diminuição da concentração de nutrientes (especialmente fósforo). A espécie Cyclotella stelligera (Bacillariophyceae) predominou junto de Aphanocapsa delicatissima, em densidade (janeiro/2000), devido ao fato de ser eficiente competidora. A classe Chlorophyceae predominou em densidade no período chuvoso (fevereiro a março de 2000), representada pelos táxons Coelastrum reticulatum e Chlorela vulgaris. A Cyanophyceae Aphanocapsa delicatissima voltou a predominar em densidade nos dois últimos meses (abril a maio de 2000), em relação à densidade, devido ao aumento da insolação e, conseqüentemente, à ocorrências de períodos de estratificações durante o período de estudo. As espécies Aulacoseira distans, Coelastrum reticulatum e Aulacoseira granulata var. granulata foram os táxons predominantes em relação ao biovolume. Os táxons predominantes no período de estudo apresentaram a seguinte composição, quanto às suas estratégias de sobrevivência: R (Aulacoseira ditans) &#8594 CS (Aphanocapsa delicatissima) &#8594 CR (Cyclotela stellygera e Coelastrum reticulatum) &#8594 CS (Aphanocapsa delicatíssima) /CR (Coelastrum reticulatum). Essas estratégias indicam um ambiente em constante transição entre períodos de estratificação e mistura. Ao se analisar a composição fitoplanctônica por grandes grupos, a seqüência de transição destes mostra um ambiente tipicamente mesotrófico. / The Reservoir of the Lobo inserted in APA (protection environmental of area) of Corumbataí, Municipal district of Itirapina, is part of the system Jacaré Guaçú. This system, in the last decades, it has been suffering impacts significant antropics. In spite of this fact, the developed work (monthly collections in nine stations in the Reservoir of the Wolf), with collection of data regarding the physical variables, chemistries and biological, among the months of june of 1999 to may of 2000, demonstrated that this system introduces a community observed similar phytoplankton her in previous works. The alterations in the community are linked to the functions of physical forces that act in the system, mainly temperature and cycles hidrologics. The horizontal distribution was verified forming two compartments; the inferior (deeper and homogeneous) and the superior (the flowing principal entrance, with macrófitas banks). Aulacoseira distans (Bacillariophyceae) it prevailed in the first three months (June to August of 1999), favored by the transparency and it mixes of the column of water. Aphanocapsa delicatissima (Cyanophyceae), in the subsequent months (September to December of 1999) it substituted in density that species, due to increase of the temperature in the column of water, beddings and the decrease of nutritious (specially match). Cyclotella stelligera prevailed Aphanocapsa delicatissima near in density (January of 2000), should be this species efficient competitor. The class Chlorophyceae prevailed in density in the rainy period (February to March of 2000), represented by the taxon Coelastrum reticulatum and Chlorella vulgaris. Aphanocapsa delicatissima prevailed in density in the last two months again (April to May of 2000) in relation to density, due to the increase of the heatstroke and, consequently, to periods of beddings. During the study period, Aulacoseira distans, Coelastrum reticulatum and (Continuing) Aulacoseira granulata were predominant taxons in relation to the biovolume. The predominant taxons in the study period, presented the following composition, with relationship to your survival strategies: R (Aulacoseira distans) &#8594 CS (Aphanocapsa delicatissima) &#8594 CR (Cyclotela stellygera and Coelastrum reticulatum) &#8594 CS (Apahnocapsa delicatissima) /CR (Coelastrum reticulatum). These strategies indicate atmosphere in constant transition among bedding periods and it mixes and when analyzing the composition phytoplankton for great groups, the sequence of transition of these, display environmental typically mesotrophic.

Thesis (M. Sc. (Zoology)) -- University of the North, 1994 / Refer to the document

Orientador: Lúcia Helena Sipaúba Tavares / Banca: Ely Nahas / Banca: Rose Meire Vidotti / Resumo: O estudo foi realizado em um viveiro de criação semi-intensiva de peixes do Centro de Aqüicultura da UNESP (CAUNESP) Jaboticabal, SP. O trabalho avaliou algumas variáveis limnológicas e fitoplâncton neste viveiro utilizado para irrigação. Foram analisados variáveis físicas e químicas (pH, oxigênio dissolvido, condutividade, temperatura, alcalinidade total, formas de carbono inorgânico, dureza, sólidos totais solúveis, demanda bioquímica de oxigênio, nitrito, nitrato, amônia, fósforo total e ortofosfato), clorofila-a e identificação dos organismos fitoplanctônicos. A temperatura sofreu influência direta das condições ambientais. A utilização deste viveiro para fins de irrigação deve ser reavaliado em função das condições de manejo e da presença de Cyanobacteria. Devido a distribuição em série em que o viveiro estudado esta incluído, provocou o aumento nas variáveis limnológicas, principalmente no período de engorda dos peixes. O manejo inadequado em piscicultura geralmente acelera o processo de eutrofização, deteriorando a qualidade da água, em função do manejo empregado principalmente, pela administração de altas doses de ração e fertilização (orgânica ou inorgânica). O objetivo do trabalho foi avaliar alguns aspectos bióticos e abióticos de um viveiro de piscicultura e sua relação direta na qualidade da água para uso múltiplo. / Abstract: This study was carried out at one semi-intensive breeding fishpond at the UNESP (CAUNESP) Aquaculture Center, in Jaboticabal, SP. The study evaluated some limnological parameters and phytoplankton of a fishpond used to irrigation. The purpose of this work was to determine physical and chemical variables (pH, dissolved oxygen, conductivity, temperature, total alkalinity, forms of inorganic carbon, hardness, total solids soluble, biochemical oxygen demand, nitrite, nitrate, ammonia, total phosphorus, and orthophosphate), chlorophyll-a and phytoplankton organisms consist. The temperature was influenced directly by climatic conditions. The utilization of this fishpond as a source of irrigation must be revaluated in function of management conditions and the presence of Cyanobacteria. In function of set up sequentially, this fishpond study had favored a change in the limnological features, mainly in the grow-out fish period. The used of inappropriate management may eventually produce the eutrophication, and water quality degradation due to the higher rates of ration and fertilizer (organic or inorganic). The present work was conducted to evaluate the biotic and abiotic aspects in the water quality of fish pond with water flow and distributed sequentially and multiple use. / Mestre

The phytoplankton, or plant plankton, live in the open water throughout their life cycle and obtain the necessary nutrients from the water. They are important contributors to the total plant production of lakes and ponds.

Blooms of the red tide dinoflagellate Karenia brevis occur annually on the west Florida shelf. In the late summer/early fall months, background concentrations increase from 103 cells L-1 to excesses of 106 cells L-1. Blooms are most common between Tampa Bay and Charlotte Harbor, and may be maintained for months. The region’s hydrography may play a role in the initiation, maintenance and termination of blooms. The west Florida shelf is depauperate in inorganic nutrients. Inorganic nitrogen and phosphorus rarely exceed the limits of detection, whereas dissolved organic nitrogen is often present at concentrations of 15 to 20 µM. Because K. brevis exhibits the ability to utilize both organic nitrogen and phosphorus, the organic pool may serve as an important nutrient source. The source of nutrients for K. brevis blooms is the focus of much scientific research. Nitrogen is considered to be the limiting nutrient in marine waters and may have several sources. Potential sources of inorganic and organic nitrogen are estuarine outflow, atmospheric deposition, upwelling, dissolved organic nitrogen released from N2 fixing cyanobacteria, diatom blooms, decaying seagrasses, fish or other organic matter. The natural abundance stable isotopic signatures of particulate bloom material (δ15N and δ13C) associated with K. brevis blooms during 1998 to 2001 was analyzed and compared with known isotopic values of potential nutrient sources. Data was analyzed from blooms occurring from 1998 to 2001. Extensive analysis of the 2001 bloom showed that the δ15N of bloom material ranged from 2 0/00 to 5 0/00. δ13C of bloom material ranged from -22 0/00 and -17 0/00. Non-bloom material was considerably more variable in both δ15N and δ13C. δ13C values were higher near shore than offshore during the 2001 bloom, suggesting lower dissolved inorganic carbon levels due to high temperature and/or high biomass. δ15N of bloom material fell within the range of the δ15N values of potential nitrogen sources. It appears that K. brevis utilizes the available nitrogen sources opportunistically, and that isotopically more depleted sources are more important. More enriched sources such as upwelled nitrate or sewage nitrogen can be excluded as significant sources based on the isotopic data.

No description available.

No description available.

Most Australian studies on estuarine plankton have examined distribution and abundance in relation to hydrological changes, primary productivity and associated nutrient dynamics. Relatively few have examined the complex interactions between zooplankton grazers and the type and quality of food available, or the role of zooplankton grazers in structuring phytoplankton communities, or their contribution to the nutrient pool. The ecological role of zooplankton grazers in the Swan River estuary, Perth, Western Australia, was examined as part of a collaborative research project directed by the Western Australian Estuarine Research Foundation, which was established in response to concern about increasing intensity and persistence of algal blooms. The present study focussed on one component of the zooplankton, the Copepoda, as model zooplankton grazers. A regular zooplankton monitoring programme, undertaken over a two year period, provided data on seasonal patterns of abundance and distribution of zooplankton over a broad spectrum of physical conditions. Relationships were identified between habitat variables, such as algal biomass, dissolved oxygen, salinity and suspended solids and zooplankton distribution, relative abundance and species composition. Prior to the inception of this study, it was assumed that copepod species composition, abundance and richness in the Swan River estuary may have changed over time, in response to long-term declines in water quality. Comparison of historical copepod monitoring data with current data did not detect any such change and it was concluded that there was greater variation in copepod species composition, abundance and richness within years than between years and that no significant change had occurred between 1966 and 1997. / However, an absence or reduction in abundance of copepods in areas of very high algal biomass (>80 pg chlorophyll a.L-1) suggests that local loss of water quality may have an impact on copepods over a small spatial scale within the estuary. Different aspects of the interactions between zooplankton grazers and phytoplankton were studied. Zooplankton grazing rates were measured in situ during algal blooms and in the laboratory under controlled conditions to determine the potential for zooplankton grazers to reduce algal biomass. Field and laboratory experiments supported the hypothesis that copepods and other zooplankton can exert 'top-down control' over phytoplankton biomass, but that the type and biomass of phytoplankton present affected their ability to exert this control. The results of the field and laboratory grazing experiments, along with literature data, were used to provide input data for a model of zooplankton and phytoplankton dynamics during a dinoflagellate bloom in the Swan River estuary. The model was tested against biomass measurements of zooplankton and phytoplankton to determine how well it predicted actual changes in the plankton community. The simulated output closely followed the measured Page x field data and fitted regression curves and provided information about diurnal patterns of phytoplankton production, respiration and migration and hydrodynamic transport, which was not available from field data. It was shown that zooplankton grazing, particularly grazing by microzooplankton, was the process contributing most to the observed decline in dinoflagellate biomass. Nutrient availability is one of several factors determining productivity of phytoplankton. Nutrients within copepod faecal pellets are relocated by faecal deposition to sediments, where microbial activity leads to the remineralisation of these nutrients. / Quantification of metabolic excretion of nutrients by copepods and the rate at which pellets are produced by copepod grazers, the concentration of nutrients within faecal pellets and the rate at which these nutrients are released indicated that copepods may play an important role in nutrient regeneration during summer and autumn when allochthonous nutrients are unavailable. At other times of the year, it is unlikely that copepods play an important role in nutrient regeneration. The research has provided a more detailed level of understanding of the interactions between zooplankton, phytoplankton and their environment. The data is ideally suited for use in a computer model to predict the effects of management actions on the Swan River estuary. This would allow pre-emptive management strategies to be developed and lessen the focus on reactive management.

When light intensities become supersaturating for photosynthesis, phytoplankton must be able to protect the photosynthetic machinery from potential damage by excess energy absorption. One of the most important photoprotective mechanisms involves the nonradiative dissipation of excess light energy by the interconversion of the carotenoid pigments of the so-called xanthophyll cycle. Very little is known about how the xanthophyll cycle of natural communities of phytoplankton responds to high light conditions and the relationship of this photoprotective mechanism to the surrounding physical environment. The purpose of this thesis was to examine the functioning, activation and relationship to the physical environment of the xanthophyll cycle in phytoplankton from the Antarctic ecosystem and the Southern Ocean. Experiments in Antarctica were conducted in austral spring under various natural and artificial light regimes including the use of a newly developed light mixing simulator (LMS). Photoprotective carotenoid pigment concentrations were determined using a carotenoid specific protocol for High Performance Liquid Chromatography (HPLC). The photoprotective xanthophyll cycle was not active in Antarctic sea ice algae under the low light conditions under the annual sea ice. When sea ice algae are exposed to high irradiance, there was an initial rapid deepoxidation of the xanthophyll pigment diadinoxanthin (DD) to diatoxanthin (DT). With on-going irradiance exposure, slower deepoxidation of DD continued. The recovery of DD in the dark or under low light was found to be significantly faster than in temperate algal communities, and is likely a particular adaptation to the unique light environment in Antarctica. The temporal accumulation of pigments of the violaxanthin (VX) xanthophyll cycle was observed for the first time in a natural phytoplankton population. It is hypothesized that the VX cycle may function as a pathway to maintain the pool of DD cycle pigments rather than as a separate photoprotective pathway as observed in higher plants. The high irradiances of ultraviolet - B (290 - 320 nm) radiation (UVB) as a result of stratospheric ozone depletion over Antarctica in spring was found to significantly impact on the DD cycle. Exposure to high levels of both ultraviolet-A (320- 400 nm) radiation (UVA) and UVB reduced the photoprotective xanthophyll pigment pool with the greatest reduction occurring after exposure to high levels of UVB. The reduction in the amount of cellular DD after exposure to high levels of UVB was greater than can be explained by deepoxidation activity, which implies that high UVB exposure can lead to a loss of DD from the community. The first-order kinetic rates of the DD cycle were found to be similar to other studies and did not vary with light intensity. Simulations under natural light using the LMS demonstrated that the response of the DD cycle to static in situ incubations and when subject to vertical mixing was not similar, and that static incubations overestimate DD-cycle activity Over the long term, algae in a simulated vertically mixed environment were able to increase the pool of xanthophyll pigments compared to static conditions where the pool remained the same or decreased. Oceanographic observations from the subantarctic waters south-east of New Zealand in austral autumn provided the physical background for new insights into the xanthophyll cycle of Southern Ocean phytoplankton. The circulation flow and water masses between the Bounty Plateau and Bollons Seamount was resolved and shown to differ from numerical models. Relatively little of the warm and salty Subantarctic Mode Water (SAMW) from the Tasman Sea is carried in the flow of the Subantarctic Front (SAF). The spatial distribution of photoprotective xanthophyll pigments showed higher than expected concentrations in the surface mixed layer of the region. The high concentration of photoprotective pigments is considered to be a consequence of the low iron concentrations in southern waters and the highly variable light and vertical mixing environment. The high cellular concentrations of photoprotective pigments constrains photosynthetic activity implying that the photoprotective pigments may play a more significant role in controlling phytoplankton production in the Southern Ocean than previously thought. Analysis of the xanthophyll pigments and physical oceanography with a Self-Organising map (SOM) Artificial Neural Network (ANN) showed that the photophysiological index DT/ (DD+DT) can be used to resolve a change in water type properties. A simple numerical model was developed which can be used to provide a quantitative index of the relative magnitudes of vertical mixing and phytoplankton photoprotection in the water column. This approach may be useful to identify the effects of physical changes in the surface mixed layer of the Southern Ocean as predicted by climate change modelling.

Interest in the effect of fish farming practices on the marine environment has arisen because there is concern that the wastes that fish farms produce may be contributing to eutrophication in coastal areas and the problem of harmful algal blooms. The focus of this thesis is an examination of phytoplankton distribution and abundance in relation to tuna fish farms in Boston Bay and near-shore Spencer Gulf. This is the first study in South Australia to define the short-term biomass fluctuations of chlorophyll and in vivo fluorescence, identify phytoplankton species distribution and abundance, including two potentially toxic dinoflagellates, and describe patch distribution relative to tuna fish farms in Boston Bay and the near-shore waters of Spencer Gulf. An ecological interpretation of phytoplankton distribution and abundance is determined and shows that community composition was different in lower Spencer Gulf compared to Boston Bay and upper Spencer Gulf sites. Pico- and nanophytoplankton were often the most abundant organisms. Diatoms and gymnoids were most common. Season and currents predominantly influenced the distribution of phytoplankton in Boston Bay and Spencer Gulf. Individual species may be influenced by inputs from the fish farms. Chlorophyll levels were different between the Spencer Gulf and Boston Bay sites and no differences were recorded, using mean levels of chlorophyll, between tuna cages and controls. Chlorophyll levels were higher east of Boston Island in autumn of 1999. Chlorophyll levels appeared to show a slight increase between years. This may have been an anomalous natural variation and future research may investigate this in the long term. In addition, Principal Components Analysis (PCA) was used to investigate differences between treatments and the functional grouping model supported an ecological interpretation of the factors from the PCA. A total of 131 taxa of phytoplankton were identified in this study. The 14 dominant taxa were used in the PCA and of these, 9 were diatoms. Phytoplankton abundance was not different between tuna cages and controls. However, when examining individual species, Karenia mikimotoi was more prevalent at tuna cages, close to shore, east and west of Boston Island than at other sites. PCA showed how different species bloomed together and were seasonal. Karenia brevis and K. mikimotoi featured predominantly in the PCA with K. brevis the dominant organism during summer and autumn along with Gyrodinium spp. and smaller gymnoids. K. brevis blooms were most likely influenced by water temperatures and fixation of nitrogen from a Trichodesmium erythaeum bloom. K. mikimotoi bloomed bimodally and may be influenced by ammonia excreted from fish from the tuna farms but , on the other hand, may be limited by the high salinities of South Australian waters. Currents in the region distribute both organisms. The final aspect of this study assessed finer temporal and spatial sampling using directional transects around tuna cages and controls using in-vivo fluorescence and size fractionated chlorophyll. The chlorophyll a sampling showed little spatial variability within a site in the 1000 m2 that the sampling area covers but far greater temporal variability (days). In contrast, fluorescence `mapping' expands the window of variability both spatially (within a site) and temporally (along transects and between days). This has given a spatial definition, which is unavailable from a single point sample, and thereby leaves room for much greater interpretation. Small patches are evident from the fluorescence mapping where this is impossible to detect from the single point samples. Therefore, the fluorescence `mapping' and patch definition show that the trend is widespread (spatially) and quite persistent (temporally) around the fish farm area. Size fractionated chlorophyll samples provided further insight into phytoplankton dynamics in this study where diatoms were favored over dinoflagellates and were responsible for the larger fraction of chlorophyll found at the tuna cage one (TC1) site. We suggest that seasonal fluctuations, high nutrient input from the farm activities and turbulence may be responsible for the different chlorophyll/fluorescent structures found at TC1. Future research may look at the long-term regional impact on phytoplankton size structure, biomass and communities from fish farm activities. As a good part of this journey involved counting phytoplankton using the Utërmohl technique, a short paper, published in the Journal of Plankton Research, on reducing the settling time of this method, is presented in Appendix.