A importância de estudos sobre a produção primária (PP) marinha é consenso devido ao seu papel no ciclo do carbono global. Técnicas rápidas e não invasivas para medição de taxas de PP foram desenvolvidas nas últimas décadas para melhorar a resolução espacial e temporal das aquisições de dados, além de suprir as desvantagens e lacunas deixadas pelos métodos clássicos que envolvem a incubação de amostras. Os objetivos deste trabalho são: (1) comparar duas técnicas mais novas, a Bio-óptica (PPabs) e a Fluorescência Ativa Variável (PPFire), com o método clássico de evolução de oxigênio pelo metabolismo da comunidade planctônica que estima a PP bruta (PPB), (2) e determinar a influência de variáveis oceanográficas e como elas podem predizer a PP no canal de São Sebastião ao longo de diferentes períodos amostrais (verões de 2014, 2016 e 2018, inverno de 2014 e primavera de 2015). A PPB variou entre 47,55 e 341,94 mg C m-3 d-1, a PPabs entre 73,7 &#177; 6,9 e 454,9 &#177; 25,8 mg C m-3 d-1 e a PPFire entre 9,0 e 57,8 mg C m-3 d-1 no verão de 2018. As relações entre os métodos foram significativas (PPB vs PPabs, p = 0,007, PPB vs PPFire, p = 0,01 e PPabs vs PPFire, p = 0,01). A partir de uma regressão linear múltipla, vimos que a PPB (p = 0,003) e PPFire (p < 0,001) foram previstas pela temperatura e pela concentração da clorofila-a, já a PPabs (p = 0,007) pelas duas variáveis adicionadas a salinidade. Esses resultados indicam que apesar dos métodos apresentarem magnitudes diferentes, informações adicionais sobre o ambiente são incorporadas por cada técnica. A PPB acrescenta informações quanto a comunidade planctônica como um todo, a PPabs sobre a composição pigmentar e de tamanhos de espécies e a PPFire sobre a fotofisiologia das células fitoplanctônicas. Quanto às condições oceanográficas, as relações com a temperatura e a salinidade indicam que os métodos são sensíveis a alteração de massas d\'água, como a Água Central do Atlântico Sul (ACAS), bem como a entrada de aporte continental por plumas de rios, que são responsáveis pela disponibilidade de luz e nutrientes que afetam a PP no canal. Concluindo, os métodos são complementares e podem variar de diferentes formas conforme a dinâmica local, no entanto, são significativamente proporcionais uns aos outros, o que indica a robustez entre as medidas das duas técnicas mais novas aqui comparadas. / There is a consensus of the importance of primary production (PP) studies due to its role on the global carbon cycle. Fast and non-invasive techniques to measure rates of PP were developed in the last few decades to improve temporal and spatial data acquisition, and to overcome disadvantages and gaps associated with classical methods using incubation of samples. The aim of this work are: (1) compare two newer techniques, Bio-optical (PPabs) and Active Variable Fluorescence (PPFire), to the classical method involving oxygen evolution by the planktonic community metabolism (PPB), and (2) determine the influence of oceanographic variables and investigate how they could predict PP in the São Sebastião channel. PPB varied between 47.55 and 341.94 mg C m-3 d-1, PPabs between 73.7 &#177; 6.9 and 454.9 &#177; 25.8 mg C m-3 d-1 and PPFire between 9.0 and 57.8 mg C m-3 d-1 in the summer of 2018. The relationships between methods were significant (PPB vs PPabs, p = 0.007, PPB vs PPFire, p = 0.01 and PPabs vs PPFire, p = 0.01). After a multiple linear regression test, we found that PPB (p = 0.003) and PPFire (p < 0.001) were predicted by temperature and chlorophyll-a concentration, however, PPabs (p = 0.007) was also predicted by salinity. These results indicate that despite the methods show different magnitudes, each one includes different information about the environment. The PPB adds overall information about the planktonic community, while the PPabs adds pigment composition and species size and the PPFire adds phytoplankton cell photophysiology. We found correlations with the different PPs and temperature and salinity indicating that the three methods are sensitive to water mass changes, as the South Atlantic Central Water (SACW) and the intrusion of river plumes in the channel, both responsible for light and nutrients availability. In conclusion, the three methods are complementary and could vary in different ways due to local dynamics. However, they are proportional to each other, showing strength to the use of the two newest techniques (PPabs and PPFire).

Ocean optical studies have been conducted extensively in open ocean waters but less so in coastal waters where the influence of human population is increasing dramatically. The waters of the Strait of Georgia, British Columbia, Canada, are very important to the rearing of young salmon and herring, and to the fishing industry of British Columbia overall. The oceanography and plankton communities of the Strait have been researched extensively, however the forces behind the frequent occurrence of phytoplankton blooms in these waters still causes debate among researchers. In order to shed some light onto this topic and increase our knowledge of the characteristics of the waters of the Strait of Georgia, optical and bio-physical data were measured in the euphotic waters of the Strait in late spring and early summer of 2006. Hyperspectral optical data were measured for the first time in these waters using in situ optical profilers to collect inherent optical properties and radiometric quantities that were later used to derive apparent optical properties. The inherent optical properties included absorption coefficient, spectral beam attenuation coefficient, chromophoric dissolved organic matter absorption coefficient, particulate absorption coefficient, and particulate scattering coefficient. In situ irradiances and radiances were used to derive various diffuse attenuation coefficients. Water masses in the euphotic zone of the Strait of Georgia were then classified into three optical water masses according to their inherent optical properties using a clustering algorithm. OM1 waters were characterized by high and spectrally-invariant particulate scattering due to inorganic particles carried by the Fraser River plume. Absorption and scattering showed some spectral dependence in OM2 waters, with particles and chromophoric dissolved organic matter contributing equally to light absorption. The deepest waters, OM3, were the least influenced by the Fraser River, and the contribution of chromophoric dissolved organic matter to absorption was greater than in OM1 and OM2. A radiative transfer model, Hydrolight, was used to model some of the optical properties that were not collected in situ and then used to assess the magnitude of light available to phytoplankton in the Strait. Based on the minimum light requirements for photosynthesis of two of the main phytoplankton species in the Strait, the analysis presented here showed that there was enough light available for photosynthesis in the photosynthetically-available radiation range for the two phytoplankton species in all three optical water masses.