DBPapers
DOI: 10.5593/sgem2012/s14.v3005

SEASONAL VARIATION OF BACTERIAL ABUNDANCE, BIOMASS AND MORPHO-STRUCTURAL DIVERSITY IN LITTORAL SANDY SEDIMENTS ON THE ROMANIAN BLACK SEA COAST

D. R. POPOVICIU, I. I. ARDELEAN
Wednesday 1 August 2012 by Libadmin2012

References: 12th International Multidisciplinary Scientific GeoConference, www.sgem.org, SGEM2012 Conference Proceedings/ ISSN 1314-2704, June 17-23, 2012, Vol. 3, 965 - 972 pp

ABSTRACT

Bacterial density, biomass and morpho-structural diversity were studied on a seasonal
basis (April 2011-March 2012) in surficial intertidal sediments from three sandy
beaches in Constanţa (Romanian sea coast). Investigation was done by epifluorescence
microscopy, employing SYBR Green I (for total cell count) and hexidium iodide (for
Gram-positive bacteria). Sediment chlorophyll concentrations were also determined,
monthly, in two of the locations. Cell density ranged between 4.32-12.64 × 107
cells/cm3 sediment, and dry biomass between 1.63-6.99 μg/cm3, with higher values in
warmer months. Most bacteria observed were Gram-negative (70-86%) and rod-shaped
(56-72%). Total chlorophyll concentrations varied significantly with location and month
(0.11-2.64 μg/cm3, with maximum values in autumn). Chlorophylls A and C were
dominant, indicating the leading role of diatoms in intertidal sediment primary
production. Statistical analysis showed that sediment bacterial density and biomass were
positively correlated to water temperature and chlorophyll concentration. The
percentage of Gram-positive bacteria and cocci tends to be higher in unfavourable
conditions: lower temperatures and primary production, larger sediment grains.
Chlorophyll concentrations showed no significant correlation to water temperature.

Keywords: bacteria, abundance, biomass, Gram character, chlorophylls, sandy
sediments.