| Fish farming has been shown to affect the microbiological composition of thesediment below the farms by introducing nutrients, causing oxygen depletion and,occasionally, exposing the sediment to antibiotics. This has been shown to disruptmicrobial ecosystem functions by decreasing species diversity, and even enrich fishand human pathogens. This study was performed to investigate the effect of pollutionfrom marine fish farms on the bacterial community structure in the underlyingsediments.This paper can be divided into three parts abOTU the temporal and tpatialdistribution of microbial community in response to fish cage farming in nanshabay.The fist aspect is diversity and distribution of bacterial community composition inNansha Bay sediment response to fish farm. The second aspect is differences inbacterial community composition in Nansha Bay sediment response to fish farm duringthe four seasons. The third aspect is diversity and distribution of SRB composition inNansha Bay sediment response to fish farm.The purpose of our study is the followingaspect: to investigate the bacterial response to organic disturbance by documenting thespatial variations of bacterial communities, to study the bacterial community changesin response to environment factors, to explore the typical microbial groups in fishfarming areas in order to provide information useful to the development of ecologicalbiomarkers for monitoring the remediation of polluted sites. Results as follows:1) Sediment samples were collected at four sites on a distance gradient away alongthe fish farm center on the coast of Nansha Bay in eastern sea, China in July2007. Thesediments of non-fish farming site (site4) was used as control. The diversity anddistribution of sediment bacterial ware analyzed through the construction of16S rDNAclone library. Most of these clones sequenced fell into six major lineages of the domainbacteria: γ-Proteobacteria, Bacteroidetes, δ-proteobacteria, β-proteobacteria, Firmicutes and Acidobacteria. Of all environmental parameters investigated, sedimenttotal inorganic nitrogen, ammonia, nitrate, nitrite, orthophosphate and sulfide werefound to impact the composition, structure, and distribution of the bacterial community.Canonical correspondence analysis (CCA) between environmental factors andabundance of16S rDNA suggests that the sulfide is the key regulator of thecomposition of bacterial community in Nansha Bay sediments and the ε-proteobacteriawere only detected from the fish farm sediment. These OTUs expand the currentknowledge of bacterial communities in marine sediment while providing informationuseful for the development of ecological biomarkers for use in monitoring theremediation of polluted sites.2) Sediment samples were collected at four seasons under the fish farm center on thecoast of Nansha Bay. The diversity and distribution of sediment bacterial wareanalyzed through the construction of16S rDNA clone library. Most of these clonessequenced fell into six major lineages of the domain bacteria: γ-proteobacteria,α-proteobacteria, δ-proteobacteria, Bacteroidetes, Firmicutes and Actinobacteria. Ofall environmental parameters investigated, sediment total inorganic nitrogen, ammonia,nitrate, nitrite, orthophosphate and sulfide were found to impact the composition,structure, and distribution of the bacterial community.3) Sulfate reducing bacteria (SRB) are important regulators of a variety of processesin coastal marine sediments regarding organic matter turnover, biodegradation ofpollutants, and sulfur and carbon cycles. Yet the investigate of microbial communitycompositions in fish farm sediments are less.This study described the diversity andspatial variation of SRB communities in surface sediments in Nansha Bay. The spatialvariation of SRB communities was described by dsrAB clone library. The resultsshowed that the most diversity were found at polluted sites. In addition, clusteranalysis indicated that although the SRB communities were different during the fourclone libraries. |
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