Optical particle measurements are emerging as an important technique for understanding the ocean carbon cycle, including contributions to estimates of their downward flux, which sequesters carbon dioxide (CO 2) in the deep sea. Optical instruments can be used from ships or installed on autonomous platforms, delivering much greater spatial and temporal coverage of particles in the mesopelagic zone of the ocean than traditional techniques, such as sediment traps. Technologies to image particles have advanced greatly over the last two decades, but the quantitative translation of these immense datasets into biogeochemical properties remains a challenge. In particular, advances are needed to enable the optimal translation of imaged objects into carbon content and sinking velocities. In addition, different devices often measure different optical properties, leading to difficulties in comparing results. Here we provide a practical overview of the challenges and potential of using these instruments, as a step toward improvement and expansion of their applications. Keywords: sinking particle fluxes, sinking velocities, carbon content, size, image processing, automated classification, in situ optical particle measurements, biological carbon pump * Different magnifications available. Quoted details are for the magnification that is most suitable for marine snow.

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The objective of this study was to describe the composition of two mesozooplankton and ichthyoplankton estuarine communities in Jandaíra, Bahia (Tabatinga River), impacted by a shrimp farm; and in Conde, Bahia (Itapicuru River), a pristine estuary. Samples were collected through horizontal hauls using a net (200 μm mesh size), coupled to a flowmeter, during the ebbing and flooding tides in April, August and December, 2007. In the Tabatinga and Itapicuru Rivers 76 and 92 taxa were registered. The most abundant groups were Pseudodiaptomus richardii and Disco sp. Acartia lilljeborgi was also dominant at Tabatinga, while Temora sp. and decapod larvae were predominant in Itapicuru River, which also presented higher densities for most planktonic taxa, particularly fish larvae. A descriptive analysis of the main taxa´s spatial distribution and new geographical records of Disco sp., P. richardi, Pontellopsis villosa, Macrosetella gracilis, Microsetella rosea, Gonyiopsillus brasiliensis, Agetus flaccus and Ergasilus caraguatatubensis were presented.

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The inner shelf waters off Southeastern Brazil are periodically enriched by bottom intrusions of the cold and nutrient-rich South Atlantic Central Water (SACW), which is transported offshore by the Brazil Current. This study examined the temporal contrasts in abundance and structure of pelagic copepod assemblages in a neritic station off Ubatuba, in relation to hydrography and phytoplankton biomass, to investigate the effects of SACW bottom intrusions on copepod population dynamics during three consecutive years. The watercolumn characteristics shifted from a well-mixed, more turbid and phytoplankton-poor scenario during subsidence conditions to a stratified, less turbid and high Chl-a concentration scenario during SACW bottom intrusions, leading to increased copepod diversity, abundance, and biomass. The rise in copepod diversity during SACW intrusions was related to the contribution of oceanic species in addition to coastal water species. The copepod community was numerically dominated by small-sized species, such as Oncaea waldemari, Oithona plumifera, and clausocalanid and paracalanid copepodids, regardless of seasonality and SACW intrusions. Some large calanoid species contributed considerably to the total copepod biomass during intrusions. In addition to confirming that SACW seasonal intrusions play a key role in pelagic processes off Southeast Brazil, this study showed that the multiannual variability of SACW seasonal intrusions is important in regulating the structure and dynamics of copepod communities in this subtropical area.

Este estudo teve como objetivo avaliar a qualidade da água das microbacias dos rios Jardim e Mutari, situadas no Extremo Sul da Bahia, através da avaliação de parâmetros físicos, químicos, microbiológicos e do uso e ocupação da terra. Para isso foram realizadas quatro coletas, em abril, maio, julho e outubro de 2019, em 8 pontos amostrais, selecionados de acordo com possíveis fontes pontuais e difusas de poluição. Foram analisados os parâmetros temperatura, potencial hidrogeniônico (pH), salinidade, oxigênio dissolvido (OD), demanda bioquímica de oxigênio (DBO), nitrito, nitrato, amônia, nitrogênio total (NT), fósforo total (PT), sólidos dissolvidos totais, coliformes totais e termotolerantes, que foram comparados com o estabelecido pela CONAMA n° 357/2005. Já as análises de uso e ocupação da terra, foram realizadas utilizando o software QGIS. Com os resultados obtidos observou-se que os parâmetros pH, OD, DBO, PT e NT apresentaram valores em desacordo com o permitido pela legislação, principalmente nos pontos próximos às áreas urbanizadas. A análise estatística multivariada PCA, permitiu identificar diferenças na qualidade da água das microbacias no período seco e chuvoso.Já o teste Kruskal-Wallis indicou diferença significativa entre os ambientes analisados. Nossos resultados indicam que é de suma importância a tomada de ações por parte do poder público que visem minimizar os impactos causados pelo uso e ocupação desordenada da terra e atividades agrícolas na qualidade da água dessas bacias hidrográficas. Cabe destacar também a importância de ações voltadas a educação ambiental principalmente da população ribeirinha.  Water Quality Assessment in Hydrographic Watersheds in the Extreme South of Bahia, BrazilA B S T R A C TThis study aimed to evaluate the water quality of the Jardim and Mutari rivers, located in southern Bahia, by means of evaluating physical, chemical and microbiological parameters and land use and occupation. Four campaigns were carried out in April, May, July, and October, 2019, at 8 stations, selected according to possible punctual and diffusive sources of pollution. The water quality results were compared with that established by CONAMA n.º 357/2005and the Water Quality Index (IQA) was calculated from these. For data analysis, Principal Component Analysis (PCA) was also performed and Kruskal-Wallis tests were applied, using the PAST software.The land use and occupation analyses were performed using the QGIS software. We observed that the pH, OD, DBO, PT and NT were in disagreement with those allowed by the legislation, mainly near urban areas. The multivariate statistical analysis PCA, allowed to identify differences in the water quality of the watersheds in the dry and rainy period. The Kruskal-Wallis test indicated a significant difference between the environments analyzed.The supervised classification confirmed the need to recover areas along the riverbed within the analyzed micro-basins.Our results indicate it is crucial that public authorities act to minimize the impacts caused by the disorderly urban occupation and agricultural activities. It is also worth mentioning the importance of actions aimed at environmental education, mainly of the riverside population.Keywords: water quality, physical, chemical and biological parameters, hydrographic basins, rivers.

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