Structuring of bacterioplanktonic populations and factors that determine the structuring of specific niche partitions have been demonstrated only for a limited number of colder water environments. In order to better understand the physical chemical and biological parameters that may influence bacterioplankton diversity and abundance, we examined their productivity, abundance and diversity in the second largest Brazilian tropical bay (Guanabara Bay, GB), as well as seawater physical chemical and biological parameters of GB. The inner bay location with higher nutrient input favored higher microbial (including vibrio) growth. Metagenomic analysis revealed a predominance of Gammaproteobacteria in this location, while GB locations with lower nutrient concentration favored Alphaproteobacteria and Flavobacteria. According to the subsystems (SEED) functional analysis, GB has a distinctive metabolic signature, comprising a higher number of sequences in the metabolism of phosphorus and aromatic compounds and a lower number of sequences in the photosynthesis subsystem. The apparent phosphorus limitation appears to influence the GB metagenomic signature of the three locations. Phosphorus is also one of the main factors determining changes in the abundance of planktonic vibrios, suggesting that nutrient limitation can be observed at community (metagenomic) and population levels (total prokaryote and vibrio counts).

No abstract

No abstract

Kelp forests in southern California are important ecosystems that provide habitat and nutrition to a multitude of species. Macrocystis pyrifera and other brown algae that dominate kelp forests, produce negatively charged polysaccharides on the cell surface, which have the ability to accumulate transition metals such as copper. Kelp forests near areas with high levels of boating and other industrial activities are exposed to increased amounts of these metals, leading to increased concentrations on the algal surface. The increased concentration of transition metals creates a harsh environment for colonizing microbes altering community structure. The impact of altered bacterial populations in the kelp forest have unknown consequences that could be harmful to the health of the ecosystem. In this study we describe the community of microorganisms associated with M. pyrifera, using a culture based approach, and their increasing tolerance to the transition metal, copper, across a gradient of human activity in southern California. The results support the hypothesis that M. pyrifera forms a distinct marine microhabitat and selects for species of bacteria that are rarer in the water column, and that copper-resistant isolates are selected for in locations with elevated exposure to transition metals associated with human activity.

No abstract

Biomonitoring in situ was performed in order to assess Sepetiba Bay's Litopenaeus schmitti efficiency as environmental contamination biomonitor, an area historically contaminated by metals and where this shrimp is the second most abundant species. Trawlings were conducted during rainy and dry seasons close to the main pollution sources to evaluate Cd, Cr, Cu, Mn, Pb, and Zn concentrations in muscle, exoskeleton, and whole body. After specimen classification, biometrics measurements, sex and age determination, samples were dried (50°C) and grinded before acid extraction of metals, followed by ICP OES quantification. Concentrations were higher in whole shrimp samples, followed by exoskeleton and subsequently muscle samples. The descending concentration order was Zn [ Cu [ Mn [ Cr [ Cd [ Pb. Comparing previous studies in the area, Pb and Zn concentrations have decreased and Cu has increased. Males and females showed no significant differences. Adults showed higher concentrations of Cr and Zn than juveniles, but bioconcentration factor did not exceed 10 -2 , except for Cu (10 -1 ). Nevertheless, it did not mean intake absence, once concentrations of Cr and Cu reached values above and close, respectively, to the consumption law.

No abstract

No abstract