Abstract
This study focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach and through the evaluation of the total bacterial count, the electron transport system activity (ETSA), the esterase activity (EST), as well as the protein and the organic matter contents. Seasonal variations of organic matter, protein content and the number of bacteria were particularly notable in the summer. ETSA reached a maximum of 7.48 µl O2 h-1 g-1 in the summer. EST activity presented a different pattern once it reached a maximum of 0.17 µg fluorescein h-1 g-1 in the winter. The temporal variation of ETSA and EST activity indicated that biopolymers predominated in the winter, and oligomers or monomers predominated in the summer. These results suggest that organic carbon turnover is more likely to be controlled by organic matter quality. The heavy metals concentrations, especially for Cu, Zn, Ni and Cr, indicated absence of the inhibition of dehydrogenase activity, and they are not bioavailable in the EC50 values
Highlights
Marine sediments are intensively colonized by microorganisms
This paper focuses on the quality of the organic matter that reaches the sediment from Boa Viagem Beach (Figure 1), and on the bioavailability of heavy metals in sediment samples in the coastal area of Niterói (RJ) through the enzymatic evaluation of the bacterial communities
Particles create a spatial heterogeneity in the distribution of organic matter, in the remineralised nutrients, and in the species composing bacterial populations (Azam et alli, 1993)
Summary
Marine sediments are intensively colonized by microorganisms (bacteria, cyanobacteria, fungi, algae). Immobilized at surfaces and embedded in an extracellular organic matrix, consisting of extracellular polymeric substances (EPS) secreted by the cells. By their organization in biofilms, the organisms create their own microhabitats with pronounced gradients of biological and chemical parameters. Along these gradients they can use substrates and energy effectively (Meyer-Reil, 1994). Their biomass is greater than the biomass of all other benthic organisms. The cell surface of the microbes by far exceeds that of all other organisms. Particulate organic matter can be decomposed in close contact with the substrate by hydrolytic enzymes (MeyerReil & Koster, 2000)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
