Bacterial diversity in organically-enriched fish farm sediments

Abstract

The bacterial diversity and community structure within both organically enriched and adjacent, unimpacted, near-shore marine sediments at two fish farms in southern Tasmania, Australia, was examined using 16S rRNA gene clone library construction and analysis. Sediments at both caged and reference sites at both farms showed a very high level of microbial diversity. Over 900 clones were analysed and grouped into 631 unique phylotypes. Reference sites were dominated by Delta- and Gammaproteobacteria and the Cytophaga-Flavobacteria-Bacteroides group. Cage site sediments were also dominated by these phylotypes, as well as members of the Alpha- and Epsilonproteobacteria. Diversity and coverage indices indicated that the actual diversity of the sediments was much greater than that detected, despite a large sampling effort. All libraries were shown to be statistically different from one another (P < 0.05). Many phylotypes did not group with cultured bacteria, but grouped with other environmental clones from a wide array of marine benthic environments. Diversity and evenness indices suggested that although both parameters changed after farming, diverse communities were present in all sediments. The response of the microbial community to organic load suggested that random, rather than predictable, succession events determine community composition and diversity, and that sediment type may influence bacterial community and sediment response to organic perturbation.

Obligate oil-degrading marine bacteria

“…In contrast to the cosmopolitan OHCBs discussed above, distribution of the psychrophilic OHCB Oleispira antarctica (55 sequences until now) is thus far limited to the colder waters found at high latitudes [38,39]: the least cold sites at which O. antarctica has been found are Cape Cod (MA, USA, GenBank Acc.Nr.AM117931) 42°04′26″N, 70°12′19″W and South Tasmania [40].…”

Flavobacterial response to organic pollution

“…This primer is highly specific to members of the class Flavobacteria (Abell & Bowman 2005b), specifically the family Flavobacteriaceae, the clone Agg58 group and the family Cryomorphaceae. Indeed, a parallel clone library survey of total bacterial diversity in the organically loaded sediments investigated herein observed that the number of clones affiliated with the Bacteroidetes increased with organic loading, and that 558f successfully targeted much of the sediment Bacteroidetes community of these sites (Bissett et al 2006). Although use of this single primer set necessarily underestimates the true Bacteroidetes community, it does allow a reasonable approximation of potentially important members of the marine sediment community in these sediments.…”

Impacts of Mariculture on the Diversity of Bacterial Communities within Intertidal Sediments in the Northeast of China

“…The possible reason was that sediment types significantly influenced the bacterial community. For example, different sediment bacterial communities in two fish farms in southern Tasmania (Australia), which have different types of sediments (muddy vs. sandy), have reported to be mainly resulted from sediment types [26].…”

“…The accumulation of organic compounds has been reported to increase the presence of α-Proteobacteria in the sediment of fish farm, suggesting their importance in organic matter decomposition [24]. The microbial communities in the sediment inside and outside of the mariculture zone were investigated in terms of their dynamic and sensitivity to environmental variation, especially eutrophication [25,26]. However, impacts of mariculture on bacterial communities, including those in sediments, remain largely unknown [27].…”