Spatial structure of the microbial community in sandy carbonate sediment

Abstract

The environmental conditions in permeable carbonate sands are in many ways different from those in fine-grained sediments, but little is known about how this affects the structure and composition of the microbial community. We studied the microbial community structure in relation to the geochemical zonation within a 4 m 2 patch of a sandy carbonate sediment in Kane'ohe Bay, O'ahu, Hawaii. Porewater concentrations of oxygen and sulfide at depths between 15 and 52 cm were measured in situ using voltammetry, and sediment samples from 0 to 5 cm, 25 to 35 cm, and 70 to 80 cm depth were used to evaluate vertical and horizontal variation in the microbial community. Anoxic, suboxic (sulfide as well as oxygen below detection limit), or oxic conditions were measured in porewater from between 15 and 32 cm below the sediment/water interface, with no consistent depth pattern. All measurements below 32 cm indicated anoxic conditions, with sulfide concentrations ranging from <10 to about 200 μM. The microbial community revealed by denaturing gradient gel electrophoresis (DGGE) was homogeneous in the surface sediment, while large variations were observed at 25 to 35 cm depth, and smaller variations occurred at 70 to 80 cm depth. Richness analysis of clone libraries from each of the 3 depths indicated that the phylotype diversity was highest in the library from 25 to 35 cm depth. We suggest that the microbial community structure is correlated to local physico-chemical conditions in the sediment and that spatio-temporally heterogeneous redox conditions result in an increased microbial diversity. A monophyletic group of phylotypes that were highly divergent from any other sequences deposited in the GENBANK database was detected in the sediment. These phylotypes may represent chloroplasts or plastids associated with eukaryotes or a new lineage of Bacteria related to the Cyanobacteria. Using specific primers, members of the group were detected in sands from several coastal sites on the island of O'ahu.

Environmental distribution of coral-associated relatives of apicomplexan parasites

“…ARL-V was once again strictly associated with coral tissue and surface: in three studies that concurrently sampled corals and surrounding water (Reis et al, 2009;Sunagawa et al, 2010;Chen et al, 2011), we found no ARL-V sequences in reef water, but identified multiple in all corals sampled. Similarly, surveys of coral reef sediment that identified sequence from other plastids, including ARL-I (Vitrella), did not contain ARL-V (Sørensen et al, 2007;Garren et al, 2009;Gao et al, 2011). Lastly, in at least one coral species examined (Isopora palifera in Taiwan) we detected ARL-V's sequence on 6 out of 7 occasions during 1 year (February and April to August; not detected in November; Chen et al, 2011), suggesting a prolonged association.…”

Microbial abundance in lacustrine sediments: a case study from Lake Van, Turkey

“…Although it was shown that there is quite considerable heterogeneity in sediments Soltwedel and Vopel 2001;Sørensen et al 2007), the extent and the effects of heterogeneity in deep subsurface sediments have not yet been studied. Such knowledge may have great implications for models of global subsurface biosphere distribution.…”

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

“…Bacteria in surface sediment have massive diversity and rapid growth rate, and their populations are largely influenced by pollutants of water columns [7,8]. Recently, molecular method-based studies have indicated that bacterial diversity in sediment has been linked with impacts of anthropogenic activities, such as increase of eutrophication and chemical pollution [9][10][11][12][13], changes in species of phytoplankton or zooplankton [14][15][16], and operating a dredging, reclamation, or remediation project [17][18][19][20].…”