The effect of environmental conditions upon the growth, production and development of river phytoplankton was investigated for the feeder rivers to the Humber Estuary. The study was part of the Land Ocean Interaction Study LOIS) and focused upon the Rivers Trent and Yorkshire Ouse. The influence of physical, chemical and biological factors upon phytoplankton development were measured through routine fieldwork and laboratory analyses. During fieldwork measurements were collected which complemented measurements collected by LOIS colleagues. Data collected in this study included phytoplankton species composition, density and biomass and is situ rates of growth and production. In situ rates of loss through grazing and respiration were also measured. Laboratory investigations concentrated upon the effects of Ught and temperature upon dominant phytoplankton species and were developed to complement fieldwork. The project focused around four main aims. These were basically to assess the size and composition of phytoplankton maxima in the Trent and Ouse, measure in situ rates of growth and production, estimate losses from grazing and to develop models, using the data collected to assess the effect of environmental conditions upon phytoplankton development and autochthonous carbon in the Humber Estuary. The results showed that phytoplankton dynamics in the Trent and Ouse were controlled primarily by discharge, light and temperature. During spring, when conditions were favourable for growth, rapid phytoplankton growth and maximum rates of production were observed. However, spring floods often interrupted die large phytoplankton populations which developed. Other factors such as grazing and sedimentation were also considered as potentially important in the loss of phytoplankton. The turbid nature of the rivers resulted in a fine balance between photosynflietic gain and respirational loss. This temporal change in environmental conditions resulted in a temporal waxing and waning of the phytoplankton. This in turn had an impact upon the seasonality of the flux of autochthonous carbon to the Humber Estuary. Laboratory investigations and development of a photosynthetic model confirmed the importance of light and temperature upon phytoplankton development in these rivers. In terms of phytoplankton growth and production and the flux of autochthonous carbon, the Trent and Ouse were found to be typical of many other European rivers. The study highlighted the importance of the Trent as a source of autochthonous carbon to the Humber Estuary.

A eficiência fotossintética do fitoplâncton da baía de Santos foi estudada através de amostras de água coletadas bimestralmente, de fevereiro a dezembro de 1976. Foram amostradas três estações consideradas as mais representativas dos diferentes ambientes da região: uma estação na boca do estuário, outra próxima à praia e a última na entrada da baía. A região despertou interesse devido à presença de poluentes das mais diversas naturezas que poderiam afetar o fitoplâncton. A análise dos parâmetros físico-químicos (transparência, temperatura, salinidade, pH, material em suspensão, Oxigênio dissolvido, nutrientes e Mercúrio) foram efetuadas pela CETESB. A determinação da biomassa do fitoplâncton foi feita pela contagem de células e por medidas da concentração de clorofila-a. A produção primária foi determinada pelo método do 14C. As amostras foram incubadas a diferentes intensidades de luz até um máximo de 60 Klux, a fim de se determinar a eficiência da fotossíntese à luz de saturação. A radioatividade das amostras foi medida pelo contador \"G-M\" e por cintilação líquida. Baseando-se na comparação dos resultados entre estes dois aparelhos, sugere-se que dados obtidos anteriormente através do contador \"G-M\" sejam corrigidos e que este equipamento não seja mais utilizado. Os resultados do Número de Assimilação, assim como da biomassa fitoplanctônica apresentaram-se bastante elevados mesmo quando comparados a outras regiões eutróficas, devido à grande quantidade de nutrientes na região. Os valores de produção primária e de número de assimilação provavelmente estão subestimados devido a diversos fatores que são discutidos no presente estudo. Foram observadas células deformadas de Skeletonema e Lepto-cylindrus. Também são discutidos as possíveis causas destas anomalias. / The phytoplankton photosynthetic efficiency of Santos Bay was studied by means of water samples colected bimensaly, from February to December, 1976. Three points were sampled, the most characteristic of the different environments in the region: one station at the estuary mouth, one next to the beach and the last one at the bay entrance. The region is interesting due to the presence of different kinds of polutants, which could afectt the phytoplankton. The analyses of the physical and chemical parameters (trans-parency, temperature, salinity, pH, suspended material,dissol-ved Oxigen, nutrients and Mercury) were carried on by CETESB. The phytoplankton standing-stock determination was made by cells counts and by clorophyll-a concentration measurements. The primary production was determined by 14C method. The samples were incubated at several light intensities up to a maximum of 60 Klux to determine the photosynthesis efficiency at the saturation light. The radioactivity of the samples was measured by \"G-M\"counter and by liquid scintillation. The comparisons of the results between both theequipments suggest that the previous data from \"G-M\" counter must be corrected and that we d\'ont should use this apparatus anymore. The results of the assimilation number, as well as the phytoplankton biomass were high even when comparing then to other eutrofic regions, because of the high leveI of nutrient of the region. The values of primary production and assimilation number probably are subestimated because of several factors that are discussed in the presente paper. Deformed cells of Skeletonema and Leptocylindrus were ob-served. The possible causes of these anomalies are also dis-cussed.

A eficiência fotossintética do fitoplâncton da baía de Santos foi estudada através de amostras de água coletadas bimestralmente, de fevereiro a dezembro de 1976. Foram amostradas três estações consideradas as mais representativas dos diferentes ambientes da região: uma estação na boca do estuário, outra próxima à praia e a última na entrada da baía. A região despertou interesse devido à presença de poluentes das mais diversas naturezas que poderiam afetar o fitoplâncton. A análise dos parâmetros físico-químicos (transparência, temperatura, salinidade, pH, material em suspensão, Oxigênio dissolvido, nutrientes e Mercúrio) foram efetuadas pela CETESB. A determinação da biomassa do fitoplâncton foi feita pela contagem de células e por medidas da concentração de clorofila-a. A produção primária foi determinada pelo método do 14C. As amostras foram incubadas a diferentes intensidades de luz até um máximo de 60 Klux, a fim de se determinar a eficiência da fotossíntese à luz de saturação. A radioatividade das amostras foi medida pelo contador \"G-M\" e por cintilação líquida. Baseando-se na comparação dos resultados entre estes dois aparelhos, sugere-se que dados obtidos anteriormente através do contador \"G-M\" sejam corrigidos e que este equipamento não seja mais utilizado. Os resultados do Número de Assimilação, assim como da biomassa fitoplanctônica apresentaram-se bastante elevados mesmo quando comparados a outras regiões eutróficas, devido à grande quantidade de nutrientes na região. Os valores de produção primária e de número de assimilação provavelmente estão subestimados devido a diversos fatores que são discutidos no presente estudo. Foram observadas células deformadas de Skeletonema e Lepto-cylindrus. Também são discutidos as possíveis causas destas anomalias. / The phytoplankton photosynthetic efficiency of Santos Bay was studied by means of water samples colected bimensaly, from February to December, 1976. Three points were sampled, the most characteristic of the different environments in the region: one station at the estuary mouth, one next to the beach and the last one at the bay entrance. The region is interesting due to the presence of different kinds of polutants, which could afectt the phytoplankton. The analyses of the physical and chemical parameters (trans-parency, temperature, salinity, pH, suspended material,dissol-ved Oxigen, nutrients and Mercury) were carried on by CETESB. The phytoplankton standing-stock determination was made by cells counts and by clorophyll-a concentration measurements. The primary production was determined by 14C method. The samples were incubated at several light intensities up to a maximum of 60 Klux to determine the photosynthesis efficiency at the saturation light. The radioactivity of the samples was measured by \"G-M\"counter and by liquid scintillation. The comparisons of the results between both theequipments suggest that the previous data from \"G-M\" counter must be corrected and that we d\'ont should use this apparatus anymore. The results of the assimilation number, as well as the phytoplankton biomass were high even when comparing then to other eutrofic regions, because of the high leveI of nutrient of the region. The values of primary production and assimilation number probably are subestimated because of several factors that are discussed in the presente paper. Deformed cells of Skeletonema and Leptocylindrus were ob-served. The possible causes of these anomalies are also dis-cussed.