Port Everglades Inlet is one of the busiest ports in the country and is a point source of pollution to surrounding beaches and offshore corals from heavy boat traffic and urban runoff. Understanding fluctuations of bacterioplankton communities in major port inlets is important due to their impacts on surrounding marine environments. To understand annual microbial fluctuations, the 16s rRNA V4 hypervariable region was sequenced using Illumina high-throughput DNA sequencing technology. Surface samples were taken weekly for one year to generate baseline fluctuations in the microbial community. Total reads of 1.4 million were generated with a final count of 16,384 Operational Taxonomic Units. The dominant phyla were Proteobacteria, Cyanobacteria, Bacteroidetes, and Actinobacteria. Pathogenic genera were detected at low abundances during peak shipping and tourist months (November –April). Results indicate significant differences in alpha diversity when comparing microbial communities in August with other times. This was likely caused by low community richness and abundance, and below-average August rainfall levels. Differences in beta diversity were significant when comparing monthly and seasonal changes. Rainfall, temperature, and nutrient trends may have affected microbial composition, specifically during the dry season that was warmer and wetter than historical averages for 2013-2014. Increased nitrogen and phosphorous concentrations were observed in the dry season months of October, December, and January potentially creating optimal bacterial growth conditions. These results can be compared with historical and future data regarding inlet microbial communities to determine underlying baselines of bacterioplankton communities and monitor the health of marine and recreational environments they impact. This study represents the first to characterize at this scale and use Illumina MiSeq technology to analyze water samples from Port Everglades.

In the Boreal region, the length of day and night varies extremely over the year and organisms are exposed to different diel (24 h) fluctuations of light and temperature. Among them are pelagic populations of bacteria that are ubiquitous in freshwater ecosystems. The structure of prokaryotic assemblages in lakes is regulated by both abiotic and biotic parameters known to have diel patterns; yet, knowledge on changes of the active bacterial community composition (aBCC) over diel cycles is limited, especially at short temporal scales. Here, measurements of physicochemical parameters, nutrient levels and chlorophyll a concentrations, characterization of the carbon pool and 16S rRNA sequencing were used to elucidate the aBCC in a peat bog and the oligotrophic lake Klocka in Jämtland county, Sweden. I show that the activity of bacterioplankton communities remained relatively stable at 6-h intervals and did not follow any diel patterns during an uneven light regime period in June. However, the activity of peat bog communities changed in a cyclic pattern over three diel cycles during an even light period in September, whereas diel changes did not substantially differentiate between sampling periods and among depths in Klocka. The results of the thesis provide valuable insights into the importance of diel cycles in bacterial diversity and community dynamics in lentic habitats.

Ziel der Arbeit ist die Analyse des Phyto- und Bakterioplanktons in der Talsperre Saidenbach sowie die Identifizierung von Einflussfaktoren auf deren Zusammensetzung. Dazu wurde die mikrobielle Gemeinschaft im Freiwasser von 2013 bis 2015 monatlich in einer Vorsperre sowie an drei Probenahmestellen im Hauptbecken der Talsperre untersucht. Zur Quantifizierung und Differenzierung des Bakterioplanktons wurden Fluoreszenzmikroskopie, Durchflusszytometrie, CARD-FISH, denaturierende Gradienten-Gelelektrophorese, Klonierung und 16S-Amplikonsequenzierung eingesetzt. Die Auswertung der Daten erfolgte durch Korrelations- und Clusteranalysen sowie NMDS unter Einbeziehung hydrophysikalischer und hydrochemischer Parameter, meteorologischer Daten sowie der Daten zur Phytoplanktongemeinschaft. Darüber hinaus wurden Verfahren zum Monitoring typischer Organismengruppen im Pelagial etabliert bzw. auf ihre Eignung hin untersucht: Die spektrofluorometrische Erfassung von Phytoplanktongruppen mit Hilfe einer Tauchsonde wurde anhand mikroskopischer Analysen des Phytoplanktons validiert. Für die Quantifizierung und Differenzierung des autotrophen Picoplanktons (APP) wurde eine durchflusszytometrische Methodik entwickelt und die Resultate ebenfalls anhand mikroskopischer Zählungen überprüft. Die mit der FluoroProbe Sonde (bbe Moldaenke GmbH) ermittelten Chlorophyll-Konzentrationen für vier Algengruppen zeigten im Vergleich zu den mikroskopischen Analysen gute Übereinstimmung für die spektrale Gruppe der Diatomeen (incl. Haptophyceen, Dinophyceen, Chrysophyceen), während für die spektralen Gruppen der Grünalgen (incl. Desmidiaceen), Cyanobakterien und Cryptophyta z.T. deutliche Abweichungen auftraten. Die relative Zusammensetzung des Phytoplanktons wies ebenfalls deutliche Unterschiede zwischen FluoroProbe-Messungen und Mikroskopie auf, die vor allem in einer Überschätzung des Anteils von Grünalgen und einer generellen Unterschätzung von Cyanobakterien anhand der Sondenmessungen bestanden. Ein wesentlicher Vorteil der Sondenmessungen besteht jedoch in der Möglichkeit zur in-situ Aufnahme von Tiefenprofilen. Die Abschätzung der Zusammensetzung und Abundanz des Phytoplanktons in der Wassersäule vor Ort kann zur gezielten Probenahme genutzt werden und ergänzend Informationen zu nicht mikroskopisch analysierten Horizonten liefern. Die Sondenmessungen eignen sich jedoch nicht als Ersatz für mikroskopische Analysen und sollten nicht unabhängig von diesen betrachtet werden. Für die Quantifizierung des APP wurde eine durchflusszytometrische Methodik entwickelt, die im Vergleich zur Mikroskopie präzise Zellzahlen ergab und auch die Anteile phycocyanin- und phycoerythrinhaltiger Picoplankter zutreffend widerspiegelte. Der geringe Zeitaufwand für die durchflusszytometrischen Messungen ermöglicht es, das APP in einer höheren räumlichen und zeitlichen Auflösung zu untersuchen. Die statistische Auswertung in Hinblick auf die erhobenen Umweltparameter zeigte für die Abundanz der Picoplankter in den oberflächennahen Wasserschichten signifikante Zusammenhänge zur Wassertemperatur und dem pH-Wert. Unter den untersuchten Nährstoffen spielte nur die Nitratkonzentration in der Vorsperre und im Unterwasservorbecken eine Rolle. In der bakteriellen Gemeinschaft der Talsperre Saidenbach und der Vorsperre Forchheim wurden als dominante Taxa anhand von Klonierung und 16S-Amplikonsequenzierung typische Süßwasservertreter der jeweiligen Phyla nachgewiesen, z.B. hgcI-clade (Actinobacteria), Limnohabitans (Betaproteobacteria) und C. Pelagibacter (Alphaproteobacteria). Clusteranalysen für DGGE-Profile und 16S-Amplikonsequenzierungsdaten zeigten häufig Ähnlichkeiten der mikrobiellen Gemeinschaft in Vorsperre und Unterwasservorbecken sowie teilweise mit Proben späterer Zeitpunkte aus den weiter stromabwärtsgelegenen Probenahmestellen (S, E). Dies spiegelt möglicherweise einen Längstransport der Arten in der Talsperre wider und bedeutet für die Bewirtschaftung, dass in Vorsperren nicht nur Nährstoffelimination durch gezieltes Phytoplanktonwachstum und –sedimentation stattfindet, sondern sich auch Bakteriengruppen etablieren, die sich bei geeigneten ökologischen Bedingungen auf stromabwärts gelegene Kompartimente der Talsperre ausbreiten können. Die Zusammensetzung des Bakterioplanktons zeigte für einen Teil der Proben jahresübergreifend wiederkehrende saisonale Muster. Vor allem Proben des Jahres 2013 unterschieden sich jedoch deutlich von den entsprechenden Zeiträumen der anderen Jahre, worin sich meteorologische Besonderheiten (verkürzte Frühjahrszirkulation, sommerliches Starkregenereignis) widerspiegeln. Für die untersuchten Umweltparameter wurden in den aufeinanderfolgenden Jahren jeweils verschiedene Zusammenhänge zur Zusammensetzung des Bakterioplanktons festgestellt. Sowohl anhand der 16S-Amplikonsequenzierungsdaten als auch der DGGE-Profile konnten keine jahresübergreifend wirksamen Umweltfaktoren ermittelt werden, was auch auf den kurzen Untersuchungszeitraum von drei Jahren zurückzuführen ist. Vor allem ist aber davon auszugehen, dass im Gewässerökosystem stets mehrere Faktoren zusammenwirken und mehrstufige, z.T. zeitlich verzögerte Beziehungen zwischen den abiotischen und biotischen Komponenten bestehen. Für die Entwicklung der Ökosystemkomponenten spielen vor allem in den meso- und oligotrophen Standgewässern auch durch die Zirkulations- und Schichtungsverhältnisse eine entscheidende Rolle, die derzeit durch klimatische Veränderungen einem starken Wandel unterworfen sind. Die entsprechenden Veränderungen der mikrobiellen Gemeinschaft sind nicht absehbar und sollten in Anbetracht ihrer Stoffwechselleistungen im Gewässer ein wesentliches Element langfristiger Untersuchungen sein. Effiziente Verfahren zur Untersuchung verschiedener Komponenten des Phyto- und Bakterioplanktons können dazu einen wichtigen Beitrag leisten.

Climate change is expected to increase the precipitation ~30% in higher latitudes during the next century, increasing the land runoff via rivers to aquatic ecosystems. The Baltic Sea will receive higher river discharges, accompanied by larger input of allochthonous dissolved organic matter (DOM) from terrestrial ecosystems. The salinity will decrease due to freshwater dilution. The allochthonous DOM constitute a potential growth substrate for microscopic bacterioplankton and phytoplankton, which together make up the basal trophic level in the sea. The aim of my thesis is to elucidate the bacterial processing of allochthonous DOM and to evaluate possible consequences of increased runoff on the basal level of the food web in the Baltic Sea. I performed field studies, microcosm experiments and a theoretical modeling study. Results from the field studies showed that allochthonous DOM input via river load promotes the heterotrophic bacterial production and influences the bacterial community composition in the northern Baltic Sea. In a northerly estuary ~60% of bacterial production was estimated to be sustained by terrestrial sources, and allochthonous DOM was a strong structuring factor for the bacterial community composition. Network analysis showed that during spring the diversity and the interactions between the bacteria were relatively low, while later during summer other environmental factors regulate the community, allowing a higher diversity and more interactions between different bacterial groups. The influence of the river inflow on the bacterial community allowed “generalists” bacteria to be more abundant than “specialists” bacteria.    Results from a transplantation experiment, where bacteria were transplanted from the northern Baltic Sea to the seawater from the southern Baltic Sea and vice versa, showed that salinity, as well as the DOM composition affect the bacterial community composition and their enzymatic activity. The results showed that α-proteobacteria in general were favoured by high salinity, β-proteobacteria by low salinity and terrestrial DOM compounds and γ-proteobacteria by the enclosure itself. However, effects on the community composition and enzymatic activity were not consistent when the bacterial community was retransplanted, indicating a functional redundancy of the bacterial communities.  Results of ecosystem modeling showed that climate change is likely to have quite different effect on the north and the south of the Baltic Sea. In the south, higher temperature and internal nutrient load will increase the cyanobacterial blooms and expand the anoxic or suboxic areas. In the north, climate induced increase in riverine inputs of allochthonous DOM is likely to promote bacterioplankton production, while phytoplankton primary production will be hampered due to increased light attenuation in the water. This, in turn, can decrease the production at higher trophic levels, since bacteria-based food webs in general are less efficient than food webs based on phytoplankton. However, complex environmental influences on the bacterial community structure and the large redundancy of metabolic functions limit the possibility of predicting how the bacterial community composition will change under climate change disturbances.

For many years, the importance of microorganisms attached to surfaces in littoral zones and wetlands has been disregarded when describing aquatic ecosystem dynamics. Supporting evidence is scarce but convincing that these microbial communities are not only very productive but can often serve as major regulators of nutrient and carbon dynamics in many freshwaters. In order to determine the quantitative importance of epiphytic bacteria for the overall carbon turnover, I compared the relative contribution of epiphytic bacteria on the submerged macrophyte Ranunculus circinatus, sediment and free-living bacteria to the total bacterial production. Sediment bacteria generally dominated total bacterial biomass in the littoral zone. Although the epiphytic biomass on R. circinatus was ten times lower than the biomass of sediment bacteria, it often contributed at least equally to the total bacterial production. Thus, the results presented in this thesis confirm that most bacterial biomass and production in shallow lakes is associated with surfaces, and that in littoral zones with dense macrophyte stands, epiphytic bacteria can contribute significantly to the overall carbon turnover. There is increasing evidence that not all cells in natural bacterial communities are metabolically active. In Lake Erken, there were large differences in the fraction of active bacteria between different habitats, while the within-habitat differences were small. The sediments had the largest bacterial fraction, followed by epiphytic bacteria, while in the water column only a few percent of the bacteria were active. In this thesis the fraction of active bacteria is connected to environmental fluctuations. I hypothesize that smaller fluctuations in chemical, biological or physical factors result in large active bacterial fractions. Thus, small environmental fluctuations within a habitat allow large active bacterial fractions, while the active fraction is constrained when the environmental fluctuations are large.

Bacterioplankton is characterized by high diversity, short generation times and rapid turnover. Despite their small size, these numerous microorganisms are a fundamental piece of aquatic ecosystems by channeling carbon to higher trophic levels through dissolved organic matter utilization. Yet, several gaps remain in our knowledge and understanding of bacterioplankton populations regarding detailed temporal dynamics, and mechanisms determining biogeographical patterns and potential responses to climate change. The aim of this thesis was to examine responses in bacterioplankton community composition and function when challenged by natural and anthropogenically-induced change in environmental conditions. High temporal resolution analysis of bacterioplankton population dynamics in the Baltic Sea indicated detailed seasonal responses. It also showed a similar but wide spectrum of niche differentiation patterns within several major bacterial groups. Analysis of geographic distributions of marine bacterial populations revealed bimodal occupancy-frequency patterns in bacterial communities, indicating that the presence of many locally rare taxa along with a few locally abundant taxa were explained by stochastic variation in colonization and extinction rates. Experimental manipulations with natural marine bacterioplankton assemblages revealed both specialist and generalist strategies in utilizing specific dissolved organic carbon compounds. When subjected to experimentally increased sea surface temperatures, lowered pH and additions of terrigenous carbon, some populations decreased in relative abundance while others were stable; concomitantly, many populations increased in relative abundance. Shifts in bacterial community composition were shown to correlate with changes in community functioning, but detection of such correlations depended largely on the detail of phylogenetic analysis and successional stage of the communities. The results in this thesis suggest that both natural and anthropogenically-induced changes in environmental conditions promote simultaneous adjustment and replacement of bacterial populations tightly linked with metabolic plasticity. These trade-offs play a significant role for understanding the relationship between bacterioplankton population dynamics and potential shifts in carbon cycling properties. We also show the importance of regional effects in shaping bacterial community composition, crucial for interpreting bacterioplankton distribution patterns. In conclusion, this thesis emphasizes the critical importance of connecting analysis of bacterioplankton population dynamics with examination of ecological mechanisms to improve our understanding of factors that regulate the distribution and activity of distinct bacterioplankton populations. / Hälften av all fotosyntes på vår planet utförs av växtplankton. De producerar organiskt material som utgör grunden för näringskedjan i havet. Ungefär hälften av det organiska material som produceras av växtplankton utnyttjas inte direkt, utan omsätts istället av bakterieplankton som lever och växer fritt i vattenmassan eller på olika partiklar. Bakterieplankton spelar därmed en nyckelroll i ekosystemet genom sin konsumtion av organiskt kol som för energi högre upp i näringskedjan. Trots deras nyckelroll i akvatiska miljöer vet vi fortfarande mycket lite om bakteriernas detaljerade säsongsmönster, mekanismer bakom rumsliga mönster och hur olika populationer kan komma att svara på klimatförändringar. Målet med denna avhandling var att undersöka hur specifika populationers dynamik och ekosystemfunktion påverkas av naturliga eller klimatorsakade förändringar i havsmiljön. Våra resultat av högupplöst säsongsbunden dynamik i Östersjöns bakteriesamhälle avslöjar en liknande bred uppdelning av ekologiska strategier inom varje större grupp av bakterier, både i relativ abundans och temporal fördelning. Utbredning i rum och tid av många lokalt ovanliga populationer jämfört med få lokalt vanliga populationer förklarades genom stokastisk variation i kolonisations- och utdöendehastigheter. Vidare tyder experimentella studier med tillsatser av olika kolkällor på att marina bakterier har olika ekologiska strategier, där populationer är specialister eller generalister i utnyttjandet av enskilda kolkällor. Med hjälp av experiment med naturliga bakteriesamhällen bekräftade vi tydliga temperatureffekter på bakteriesamhällets sammansättning, och en mindre effekt av lägre pH - som dock tillsammans med förhöjd temperatur bidrog till en tydlig synergistisk effekt på artsammansättningen. Ökad temperatur tillsammans med tillsats av terrestert kol gav också en stor effekt på bakteriesamhällets struktur och ekosystemfunktion och pekar på en potentiellt viktig påverkan av ökad framtida nederbörd och avrinning från vattendrag till havet. Samtliga tre experiment med fokus på klimatpåverkan bekräftade förekomsten av populationer som försvann eller minskade i relativ abundans vid klimatpåverkan (känslighet), medan andra var stabila (resistens). Samtidigt svarade många populationer positivt på klimatorsakade förändringar i havsmiljön och ökade i relativ abundans (respons) samtidigt som bakteriernas ekosystemfunktion påverkades positivt. Sammanfattningsvis visar denna avhandling att vissa nya bakteriepopulationer kan etablera sig och ersätta andra samtidigt som vissa befintliga populationer anpassar sin livsstrategi och ekologi till förändringar i havsmiljön. Vi visar också vikten av regionala effekter, d.v.s. kolonisation och utdöende, för bakteriesamhällets struktur, viktigt för tolkningen av biogeografiska mönster och den genomiska potentialen hos specifika populationer. Denna avhandling poängterar därmed betydelsen av att koppla studier av ekologiska mekanismer till både rumsliga och temporala spridningsmönster hos bakterier och till populationers kapacitet att svara på och anpassa sig till förändringar i havsmiljön.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第20953号 / 理博第4405号 / 新制||理||1633(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 中川 尚史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DFAM

Made available in DSpace on 2014-12-17T15:54:48Z (GMT). No. of bitstreams: 1 LuizSodreN.pdf: 706113 bytes, checksum: 88c078a470be695106dfecd70878c72e (MD5) Previous issue date: 2008-02-19 / During the dry and rainy periods, in the Piranhas-Assu river hydrographic basin, variations in bacterioplankton and trophic state indexes were studied in the lotic and lentic environments. The means of total bacterial density wavered in the order of 107 organisms. mL-1 and they were higher in the rainy period. Cocci bacteria were numerically predominant in all sampling points, influencing the total abundance of bacterioplankton. Total bacterial biomass varied from 659 to 1997,3 ?gC.L-1 due to the high values of filaments cellular volume. Total phosphorus amounted 108 ?g.L-1 and it had a positive correlation with chlorophyll a (r = 0,94; p < 0,05) during dry period, when these variables presented higher concentrations. There wasn t a high spatial variation. The low transparency of water and the phosphorus and chlorophyll concentrations indicated eutrophic or hipereutrophic levels in studied points of reservoir. These variables, associated with high density and biomass values found, alert to the necessity of a constant monitoring of the semi-arid aquatic ecosystems, where the quality of water is affected by dry occurrence / Varia??es no bacteriopl?ncton e nos ?ndices de estado tr?fico em ambientes l?tico e l?ntico de trechos da bacia hidrogr?fica do rio Piranhas-Assu foram estudadas nos per?odos seco e chuvoso. As m?dias das densidades bacterianas totais oscilaram na ordem de 107 organismos por mL de amostra, sendo mais elevadas no per?odo de chuva. As c?lulas em forma de cocos foram numericamente predominantes em todos os locais, influenciando consideravelmente a abund?ncia total do bacteriopl?ncton. A biomassa bacteriana total variou de 659 a 1997,3 ?gC.L-1 em fun??o dos altos valores de biovolume dos filamentos. O f?sforo total atingiu 108 ?g.L-1 e teve uma correla??o positiva com a clorofila a (r = 0,94; p < 0,05) no per?odo de estiagem, quando estas duas vari?veis apresentaram concentra??es mais elevadas. N?o houve varia??o espacial marcante. A baixa transpar?ncia da ?gua e as concentra??es de f?sforo e clorofila indicaram n?veis eutr?fico ou hipereutr?fico nos pontos estudados no reservat?rio. Estes fatores, associados aos altos valores de densidade e biomassa encontrados, alertam para a necessidade de um freq?ente monitoramento dos ecossistemas aqu?ticos de regi?o semi-?rida onde a qualidade da ?gua ? afetada pela ocorr?ncia de seca

O bacterioplâncton é um dos grupos de organismos responsáveis pela remineralização de nutrientes em ecossistemas aquáticos, bem como produtor de biomassa através da alça microbiana. Compreender a dinâmica dessa comunidade em função da variação térmica, disponibilidade de recursos e pressão de predação pode fornecer elementos que auxiliem no gerenciamento dos recursos hídricos, através da aplicação direta desse conhecimento ou como subsídios na interpretação do resultado de simulações através de modelos ecológicos. Este trabalho teve como objetivo verificar a existência de heterogeneidade espacial e temporal na estrutura da comunidade bacteriana, densidade, biomassa e riqueza de morfotipos, na Lagoa Mangueira, bem como identificar as variáveis limnológicas que direcionam esses padrões. Foi evidenciada presença de heterogeneidade temporal, sazonal, e espacial do bacterioplâncton associada a dinâmica das variáveis limnológicas. A temperatura e a disponibilidade de nutrientes foram as principais variáveis que regularam as comunidades planctônicas, biomassa algal, bacterioplâncton e zooplâncton. Observou-se controle lateral, competição por nutrientes, entre as comunidades produtoras. O controle descendente, predação, mostrou ter importante efeito sobre o bacterioplâncton, mais especificamente sobre o morfotipo coccus, durante o verão e o inverno, sendo essa comunidade controlada de forma ascendente durante o outono e a primavera, principalmente por nitrogênio. Durante o inverno, a comunidade bacteriana apresentou significativa redução de densidade e biomassa, sendo que essa resposta pode estar relacionada às baixas temperaturas da água. A forma coccus foi o principal morfotipo produtor de biomassa e de maior densidade na lagoa. Importante heterogeneidade espacial foi observada na Lagoa Mangueira para as variáveis abióticas, visto que as regiões norte e sul apresentaram a maior diferenciação espacial, influenciada pela dimensão da lagoa. Fósforo total e carbono orgânico total regularam a comunidade bacteriana no norte da lagoa, especialmente os morfotipos coccus, curved e outros. Entre as zonas da lagoa, a margem oeste e leste foram as mais distintas em função da disponibilidade de nutrientes, destacando-se o carbono inorgânico total. A densidade bacteriana foi maior durante o verão, outono e inverno na região pelágica e durante a primavera na margem oeste da lagoa. A comunidade fitoplanctônica apresentou uma distribuição espacial caracterizada por maiores densidades nas regiões norte e centro da lagoa e na zona pelágica. O fósforo foi a principal variável limitante para as comunidades produtoras, fitoplâncton e bacterioplâncton, sendo o controle ascendente o principal regulador dessas comunidades, visto que o controle descendente não foi observado. Quanto à dinâmica dos organismos planctônicos e das variáveis limnológicas associados ao perfil de profundidade, a Lagoa Mangueira não apresentou estratificação das variáveis e consequentemente das comunidades planctônicas, resultado relacionado a uma possível característica de mistura completa da massa d’água, mesmo com ventos de baixa intensidade. As comunidades planctônicas apresentaram maior densidade durante o inverno, direcionadas pela maior disponibilidade de nitrogênio e fósforo. / Bacterioplankton is one of the groups of organisms responsible for the remineralization of nutrients in aquatic ecosystems, as well as a producer of biomass through the microbial loop. Understanding the dynamics of this community due to the thermal variation, resource availability and predation pressure may provide data to assist in the management of water resources through the application of that knowledge or direct subsidies in the interpretation of the results of simulations using ecological models. This work aimed to verify the existence of spatial and temporal heterogeneity in bacterial community structure, density, biomass and richness of morphotypes in Mangueira Lake, as well as identify the limnological variables that drive these patterns. We evidenced the presence of temporal heterogeneity, seasonal and spatial dynamics of bacterioplankton associated with limnological characteristics. The temperature and nutrient availability were the main variables that regulated the planktonic communities, algal biomass, bacterioplankton and zooplankton. There was lateral control, competition for nutrients, between the producing communities. The top down control, predation, was shown to have important effects on the bacterioplankton, more specifically on the coccus morphotype during the summer and winter, and this controlled community in bottom up controled during the fall and spring, mainly nitrogen. During the winter, the community had a significant reduction in bacterial density and biomass, and this response may be related to low water temperatures. Morphotype coccus was the main producing biomass and higher density in the lake. Important spatial heterogeneity was observed at Mangueira Lake for the abiotic variables, whereas the northern and southern regions had the highest spatial differentiation, influenced by the size of the lake. Total phosphorus and total organic carbon regulated bacterial community in the north of the lagoon, especially coccus morphotypes, curved and ‘others’. Among the areas of the lake, the west border and east were the most different depending on the availability of nutrients, especially if the total inorganic carbon. The bacterial density was higher during the summer, autumn and winter in the pelagic region and during the spring on the west border of the lake. The phytoplankton community showed a spatial distribution characterized by higher densities in the north and center of the lake and the pelagic zone. Phosphorus was the main variable limiting communities producing, phytoplankton and bacterioplankton, and bottom up control of these communities, since the top down control was not observed. Considering the dynamics of planktonic organisms and limnological variables associated with the depth profile, the Mangueira Lake did not show stratification of variables and consequently the planktonic communities, the result can be related to a characteristic of complete mixing of water mass, even with low wind intensity. The planktonic communities showed higher densities during the winter, driven by increased availability of nitrogen and phosphorus.

Made available in DSpace on 2014-12-17T14:01:58Z (GMT). No. of bitstreams: 1 MargaridaLMNS.pdf: 1054716 bytes, checksum: bc213979524001331468154edb0d566e (MD5) Previous issue date: 2008-02-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / This work aimed to study the structure and dynamic of Phytoplankton and Bacterioplankton in a complete cycle of shrimp cultivation (Litopenaeus vannamei) and determine the environmental factors responsible for the structural changes of these communities. The study was realized in a saltwater shrimp farm (Maca?ba, RN), between September/2005 and February/2006, and in a freshwater shrimp farm (Cear? Mirim, RN), between May/2007 and September 2007. The samplings were collected weekly in saltwater farm and every fifteen days in freshwater farm. Total phosphorus, chlorophyll a and environmental parameters (pH, dissolved oxygen, salinity, temperature, depth and water transparency) were measured. Qualitative and quantitative analysis of the phytoplankton and bacterioplankton were carried out. The Shannon-Wiener ecologic indexes of diversity and the Pielou equitability indexes were calculated to the phytoplankton. Bacterial density was determined by epifluorescence microscopy. The data were statistically analyzed by Pearson correlation and t-Test. Chlorophycea were predominat in salt water and in the captation/drainage point (24 to 99%). Diatoms had higher wealth. The species Choricystis minor had the highest occurrence (100%) and dominance (90-100%), thus showing its adaptation to the high temperatures, salinity and low water transparency conditions. Filamentous Cyanobacteria like Oscillatoria sp., Pseudoanabaena sp. and Phormidium sp. had constant levels. The negative correlation between chlorophycea and water transparency, and the positive correlation between chlorophyll a and salinity, showed that the phytoplankton was well adapted to the low transparency and to the high salinity. The bacterioplankton was negatively correlated with the total phosphorus and salinity. In freshwater, Cyanobacteria were predominant (>80%), presenting some producers of toxins species like Microcystis sp., Aphanizomenon sp., Cylindrospermopsis raciborskii e Anabaena circinalis. Cyanobacterial density and total phosphorus and chlorophyll a concentrations exceeded the maximum value allowed by legislation. The means of total phosphorus varied from 264 to 627 Wg.L-1 and the means of chlorophyll a oscillated between 22 and 182 Wg.L-1. The phytoplankton species were selected by low availability of the light, high pH, temperature and high availability of total phosphorus. The bacterioplankton showed high densities (5,13 x 107 to 8,50 x107 Bac.mL-1). The studied environments (ponds and rivers) presented a high level of trophic state based on the high concentrations of chlorophyll a and total phosphorus and cyanobacteria dominance. The composition of species in the ponds and rivers was similar, as well as high concentrations of total phosphorus and chlorophyll a, highlighting the pollution caused by the discharges of the farms in natural environment / O presente trabalho teve como objetivo estudar a estrutura e din?mica do fitopl?ncton e bacteriopl?ncton em ciclos completos de cultivos de camar?o (Litopenaeus vannamei), determinar os fatores ambientais respons?veis pelas mudan?as estruturais destas comunidades. O estudo foi realizado em duas fazendas de camar?o: uma de ?gua salgada (Maca?ba, RN) entre setembro de 2005 a fevereiro de 2006 e outra de ?gua doce (Cear? Mirim, RN), durante o per?odo de maio de 2007 a setembro de 2007. As coletas tiveram periodicidade semanal no viveiro de ?gua salgada e quinzenal no viveiro de ?gua doce. Foram determinadas clorofila-a e f?sforo total e par?metros ambientais foram medidos (pH, oxig?nio dissolvido, salinidade, temperatura, transpar?ncia e n?vel da ?gua). An?lises qualiquantitativas do fitopl?ncton e bacteriopl?ncton foram realizadas. Os ?ndices ecol?gicos de diversidade de Shannon-Wiener e equitabilidade de Pielou foram calculados para a comunidade fitoplanct?nica. A densidade bacteriana foi realizada por microscopia de fluoresc?ncia. Os dados foram analisados estatisticamente atrav?s da correla??o de Pearson e teste t. No viveiro de ?gua salgada e no ponto de capta??o-drenagem as clorof?ceas foram dominantes (24 % -99%) e as diatom?ceas tiveram maior riqueza. A esp?cie Choricystis minor foi a esp?cie de maior ocorr?ncia (100%) e domin?ncia (90-100%), mostrando-se bem adaptada a condi??es de altas temperaturas e salinidade e baixa transpar?ncia da ?gua. Cianobact?rias filamentosas como Oscillatoria sp., Pseudoanabaena sp. e Phormidium sp. foram constantes. A correla??o negativa, entre o grupo clorof?cea e a transpar?ncia, e positiva, entre clorofila-a e salinidade, demonstrou que o fitopl?ncton esteve bem adaptado ? baixa transpar?ncia e elevada salinidade. O bacteriopl?ncton correlacionou-se negativamente com a salinidade e f?sforo total. No viveiro de ?gua doce, cianobact?rias foram dominantes (>80%), apresentando algumas esp?cies produtoras de toxinas como Microcystis sp., Aphanizomenon sp., Cylindrospermopsis raciborskii e Anabaena circinalis. A densidade de c?lulas de cianobact?rias, os n?veis de f?sforo e clorofila-a excederam o valor m?ximo permitido pela legisla??o. Os valores m?dios do f?sforo total nos ambientes estudados foram de 264 a 627 Wg.L-1e para clorofila-a foi de 22 a 182 Wg.L-1. As esp?cies do fitopl?ncton foram selecionadas pela baixa disponibilidade de luz, alto pH, temperatura e elevada disponibilidade de f?sforo total. O bacteriopl?ncton apresentou elevada densidade (5,13 x107 a 8,50 x107 Bac.mL-1). Os ambientes estudados (viveiros e rios) configuram elevado estado de trofia, com base nas altas concentra??es de clorofila-a e f?sforo total e domin?ncia de cianobact?rias. A composi??o de esp?cies nos viveiros e nos rios (ponto de capta??o/drenagem) foi semelhante, assim como altos valores de concentra??es de f?sforo e clorofila-a, evidenciando o efeito poluidor das descargas dos viveiros no ambiente natural