Based on a field study and several mesocosm experiments, I evaluated the use of pigments as chemotaxonomical biomarkers for phytoplankton community composition in the Baltic Sea and I examined effects of inorganic nutrients on the dynamics of carotenoids and thiamine (vitamin B1) at the phytoplankton–copepod level in marine pelagic food webs. My results show that HPLC pigment analysis combined with CHEMTAX data processing was an accurate alternative to microscopic analysis of Baltic Sea phytoplankton. Experimental supply of N, P and Si affected copepod growth and biochemical status via changes in biomass and composition of their phytoplankton diet. Net population growth rates were generally higher when phytoflagellates dominated (low Si:N ratio) and lower when diatoms dominated (high Si:N ratio). Copepod body concentrations of astaxanthin decreased with fertilization. Correlations with reduced under-water irradiance were consistent with the photo-protective function of this antioxidant. Thiamine concentrations in phytoplankton also decreased with fertilization. In copepods, low Si:N ratios resulted in higher thiamine concentrations than high Si:N ratios. Thiamine concentration and degree of phosphorylation were useful as indicators of thiamine shortage both in phytoplankton and copepods. The concentrations of thiamine and astaxanthin in the copepod communities were positively correlated. As copepods constitute a major link between pelagic primary producers and higher trophic levels, fertilization effects may be responsible for astaxanthin and thiamine deficiencies in salmon suffering from the M74 syndrome, which appeared concurrently with large-scale eutrophication in the Baltic Sea. As both thiamine and astaxanthin are deficient in M74-affected salmon, there is a need for physiological and molecular investigations of possible interactions between the two compounds in living cells.

Made available in DSpace on 2016-06-02T19:29:19Z (GMT). No. of bitstreams: 1 2644.pdf: 2638689 bytes, checksum: cf5e650350ebbc1f284f3a7128a098e4 (MD5) Previous issue date: 2009-08-28 / Universidade Federal de Sao Carlos / The aim of this work was to study the phytoplankton structure of lentic and lotic systems of Tietê/Jacaré basin located in São Paulo State and the relationship between the composition and dominance of phytoplankton organisms with the water quality and trophic state of the rivers and lakes of this basin. The Tietê/Jacare basin is composed by three main rivers: middle Tietê, Jacaré Guaçu and Jacaré Pepira rivers with their sub basins: Jacaré Guaçu, Jacaré Pepira, middle river Tietê, Bauru and Jau river sub basin. Two lentic systems located in the middle Tietê are Bariri (UHE Alvaro de Souza Lima) and Ibitinga reservoirs, and Broa reservoir (UHE Carlos Botelho) in Jacare Guaçu sub basin. The limnological variables which are responsible by the water quality and its trophic state index were analysed in the two periods of the year dry and wet seasons. They were measured pH, temperature, dissolved oxygen, oxide-reduction potential, total dissolved solids, electric conductivity, alkalinity, hardness, water transparency, total particulate phosphorous, total dissolved phosphate, total inorganic phosphate, silicate, total suspended solids, total nitrogen, ionic components (fluoride, chloride, nitrite, bromide, nitrate, sulfate, ammonium, potassium, magnesium and calcium), dissolved and particulate organic carbon, dissolved inorganic carbon, chlorophyll a. Regarding phytoplankton community, the identification was made at the genus level, and the richness, diversity index equitability and dominance were analyzed to establish the relation between trophic state and the dominance of different phytoplankton classes as well as the richness and diversity of organisms both in lentic and in lotic ecosystems. Also short term variation of physical and chemical variables promoted by the cold fronts was studied in the Bariri reservoir to verify the occurrence of thermal stratification and destraification that affect the composition structure of phytoplankton and its spatial distribution. / Este trabalho teve como objetivo estudar a estrutura fitoplanctônica dos sistemas lênticos e lóticos da bacia do Tietê/Jacaré, localizada no estado de São Paulo, quanto à composição e dominância dos organismos fitoplanctônicos com a qualidade e estado trófico dos rios e lagos desta bacia. A bacia do Tietê/Jacaré é composta por três rios principais: médio Tietê, Jacaré Guaçú e Jacaré Pepira, Essa bacia é composta por cinco sub bacias: Jacaré Guaçú, Jacaré Pepira, Médio Tietê, Bauru e Jaú. Foram estudados três sistemas lênticos, o reservatório do Broa (UHE Carlos Botelho) localizado na sub-bacia Jacaré Guaçú e os reservatórios de Bariri (UHE Álvaro de Souza Lima) e Ibitinga, localizados na sub-bacia do médio Tietê. As variáveis limnológicas responsáveis pela qualidade da água e pelos índices do estado trófico foram analisadas em dois períodos do ano: estação seca e chuvosa. Foram medidas as seguintes variáveis: pH, temperatura, oxigênio dissolvido, potencial de oxido redução, sólidos totais suspensos, condutividade, alcalinidade, dureza, transparência da água, fósforo total particulado, fosfato total dissolvido, fosfato inorgânico dissolvido, silicato, material em suspensão total, nitrogênio total, compostos iônicos (fluoreto, cloreto, nitrito, brometo, nitrato, sulfato, amônio, potássio, magnésio, e cálcio), carbono orgânico dissolvido e particulado, e carbono inorgânico dissolvido, clorofila a. A comunidade fitoplanctônica foi identificada a nível de gêneros e riqueza, diversidade, equitabilidade e dominância, foram analisadas. Relação entre estado trófico dos sistemas e dominância das classes fitoplanctônicas foi analisada tanto nos ecossistemas lênticos como nos lóticos. Além disso, variações de curto prazo nas variáveis físicas e químicas promovidas por frentes frias foram estudadas no reservatório de Bariri para verificar a ocorrência e dispersão de estratificação térmica na coluna d água que pudessem afetar a composição e estrutura do fitoplâncton e sua distribuição espacial.