VOLUM OMAGIAL - Facultatea de Ştiinţe ale Naturii şi Ştiinţe Agricole

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Simona Ghiţă et al. / Ovidius University Annals, Biology-Ecology Series 14: 127-137 (2010) [22] STODEREGGER K.E. & HERNDL G.J., 2002 - Distribution of capsulated bacterioplankton in the North Atlantic and North Sea. Microb. Ecol., 44: 154-163. [23] SHERR B., SHERR E.B., DEL GIORGIO P., 2001- Enumeration of total and highly active bacteria. Methods in Microbiology, 30: 129- 161. [24] KOGURE K., SIMIDU U., TAGA N., 1979- A tentative direct microscopic method for counting living marine bacteria. Can.J.Microbiol, 25:415-420. [25] WEINBAUER M.G., BECKMANN C., HOFLE M.G., 1998 – Utility of green fluorescent nucleic acid dyes and aluminium oxide membrane filters for rapid epifluorescence enumeration of soil and sediment bacteria. Appl. Environ Microbiol, 64: 5000-5003. [26] http://rsbweb.nih.gov/ij/ [27] http://sites.google.com/site/cellcsoftware/ [28] ALMESJÖ L. & ROLFF C., 2007 - Automated measurements of filamentous cyanobacteria by digital image analysis. Limnol.Oceanogr. Methods, 5: 217-224. [29] KEPNER R.L. & PRATT J.R., 1994- Use of fluorochromes for direct enumeration of total bacteria in environmental samples: past and present. Microbiological, 58: 603-615. 137
Ovidius University Annals of Natural Sciences, Biology – Ecology Series Volume 14, 2010 CHANGES IN BACTERIAL ABUNDANCE AND BIOMASS IN SANDY SEDIMENT MICROCOSMS SUPPLEMENTED WITH GASOLINE Dan Răzvan POPOVICIU 1 , Ioan ARDELEAN 1,2 1 Ovidius University of Constanţa,Natural Sciences and Agricultural Sciences Faculty, Mamaia Avenue, no. 124, Constanţa, 900527, Romania, e-mail: dr_popoviciu@yahoo.com 2 Biology Institute of Bucharest, Splaiul Independenţei, no. 296, 060031 Bucureşti, Romania, email:ioan.ardelean57@yahoo.com __________________________________________________________________________________________ Abstract: Bacterial abundance, biomass and morphological diversity were studied in three marine sediment microcosms: control, sediment supplemented with gasoline, and sediment supplemented with gasoline and ammonium nitrate. Microbial density (4.7-6.65 × 10 6 cells/cm 3 sediment in uncontaminated samples) and biomass (1.72-3.13 µg/cm 3 sediment) dropped significantly after gasoline addition. Ammonium nitrate favoured a faster recovery to initial values. Gasoline contamination also modified the proportion of bacterial morphotypes, increasing the percentage of rod-shaped cells. Keywords: Bacteria, microcosms, hydrocarbons, abundance, biomass, morphotypes, sandy sediments. __________________________________________________________________________________________ 1. Introduction Hydrocarbon contamination is one of the most frequent and most dangerous forms of pollution affecting marine environments. Studying its effects on prokaryote communities is important, both theoretically and practically, opening the way to bioremediation. From a microbiological point of view, sediments and not the water column are the richest marine environment. Both sandy and muddy sediments show significant amounts of prokaryotes, playing a key role in the decomposition of organic matter and nutrient recycling.. Abundance, biomass and composition of sediment bacterial communities can be determined by many factors, such as the granulometric characteristics of the sediment, water dynamism, oxygenation, protozoan grazing etc [1, 2, 3]. Even though they cover a large part of the marine littoral enviroment, coastal sands are the less studied [1]. In order to evaluate the response of bacteriobenthos to various environmental changes, microcosms represent extremely valuable tools [4, 5]. The objective of the present study was to determine the effects of hydrocarbon addition on the abundance, biomass and morphological diversity of bacteria in marine sandy sediment microcosms. 2. Material and Methods Microcosms. Sandy sediment was collected from the mediolittoral of a sandy beach in Constanţa, relatively close to the central headquarters of the “Ovidius” University, and wet sieved through a 2 mm sieve (in order to eliminate large particles and macrofauna) [6]. Three 1.4 L transparent plastic recipients were filled each with around 500 cm 3 of sand, covered by a 200 mL sea water column. All the microcosms were covered with transparent caps and stored at constant temperature (18°C) with illumination simulating the day-night cycle. The control microcosm was labeled “A”. Microcosm B was supplemented with 95 gasoline (1% final concentration). Microcosm C was supplemented with the same amount of gasoline, plus ammonium nitrate as a nutrient (0.005% final concentration). Sampling and fixation. Five samples consisting of sediment cores were collected from each microcosm at time intervals of 14 days. The first series of cores was taken just before the addition of gasoline and nutrient. ISSN-1453-1267 © 2010 Ovidius University Press
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VOLUM OMAGIAL - Facultatea de Ştiinţe ale Naturii şi Ştiinţe Agricole

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