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Water temperature controls the physiology, growth rate, distribution, and behavior of most plankton populations in the sea and thus affects the energy transfer in marine ecosystems. The present study focuses on the influence of seasonal changes in sea surface temperature on phytoplankton and the size distribution of copepods in the Arraial do Cabo Upwelling System (Brazil), where a wind-driven coastal upwelling can lead to multiple distinct bottom-up cascade effects on the food web. To address the potential effect of the seasonal changes, environmental data were obtained and the abundance of plankton determined from monthly samples collected in triplicate from 2010 to 2014. The samples were analyzed on a Benchtop FlowCAM (FC), and copepods (<1000 µm) were classified according to their Ellipses Equivalent Major Axis using image analysis software ImageJ (IJ). For IJ analysis, a batch-processing macro was built to open all FC raw images and then crop each copepod individually into a single picture. Using these images, prosome and urosome lengths were manually measured with the straight-line tool in IJ. With the combinations of measurements obtained in the IJ adjusted as FC measurements, we established a new, faster, and more effective way to measure copepods. With the copepod size classification, we found that there is a cycle in copepod size combined with the upwelling cycle that is related to temperature rather than to phytoplankton growth. Copepod abundance as a whole peaked during the autumn, winter, and spring seasons. The method performed here proved that FC is an effective tool for classifying copepod sizes and detecting seasonal variation. [ABSTRACT FROM AUTHOR]

The article discusses the results of a study which examined the structure of copepod assemblages in the region of the Campos Basin in southern Brazil for a one-year period. The temperature and salinity of zooplankton samples were determined and the mean densities of the assemblages were compared in four identified water masses including tropical water and North Atlantic deep water. Tropical characteristics were observed in the copepod assemblages of the Campos Basin which were numerically dominated by epipelagic species. The study concluded that variations in the copepod community along the water column of the South Atlantic were closely related to the distinct water masses.

We report on morphological abnormalities observed in Acartia lilljeborgi in Espirito Santo Bay (E.S. - Brazil). Samples were collected atsix stations; five inside the bay and one outside of it, in March 1991-92 (raining season) and September 1991-92 (dry season) during 3 days. Biotic and abiotic variables were also determined. About 30% of the specimens exhibited morphological abnormalities, such as intestinal prolapse and partial rupture of the chitinous carapace accompanied with a mass extrusion of cell material and protoplasm. The proportionof young forms of A. lilljeborgi with abnormalities was greater thanthat of adult forms (59%). A. lilljeborgi can therefore be used as apossible indicator of environmental conditions in the bay. [ABSTRACT FROM AUTHOR]

Bioseston is a heterogeneous assemblage of bacterioplankton, phytoplankton, zooplankton, and planktonic debris. A detailed knowledge of biosestons is essential for understanding the dynamics of trophic flows in marine ecosystems. The distributional features of seston biomass in plankton (micro- and mesoplankton) in the Southwest Atlantic Ocean (Rio de Janeiro State, Brazil) were analyzed using stratified samples gathered to a depth of 2,400 m during night time. The horizontal pattern of biomass distribution was analyzed vis-a-vis station depth during both wet and dry periods, with higher values recorded in the continental shelf than in the slope, confirming the terrestrial contribution of nutrient sources to the marine environment. This horizontal variation reinforces the occurrence of seasonal vortices in Cabo Frio and Cabo de São Tomé on the central coast of Brazil. Environmental variables reflect the hydrological signatures of the water masses along the Brazilian coast. The largest seston biomass was related to high temperatures, salinities, and low inorganic nutrient concentrations in tropical and South Atlantic central waters. The observed distribution patterns suggest that seston biomass in plankton in the region may be structured based on partitioned horizontal and vertical habitats and food resources.