Abstract
BackgroundMarine microbial communities have been essential contributors to global biomass, nutrient cycling, and biodiversity since the early history of Earth, but so far their community distribution patterns remain unknown in most marine ecosystems.Methodology/Principal FindingsThe synthesis of 9.6 million bacterial V6-rRNA amplicons for 509 samples that span the global ocean's surface to the deep-sea floor shows that pelagic and benthic communities greatly differ, at all taxonomic levels, and share <10% bacterial types defined at 3% sequence similarity level. Surface and deep water, coastal and open ocean, and anoxic and oxic ecosystems host distinct communities that reflect productivity, land influences and other environmental constraints such as oxygen availability. The high variability of bacterial community composition specific to vent and coastal ecosystems reflects the heterogeneity and dynamic nature of these habitats. Both pelagic and benthic bacterial community distributions correlate with surface water productivity, reflecting the coupling between both realms by particle export. Also, differences in physical mixing may play a fundamental role in the distribution patterns of marine bacteria, as benthic communities showed a higher dissimilarity with increasing distance than pelagic communities.Conclusions/SignificanceThis first synthesis of global bacterial distribution across different ecosystems of the World's oceans shows remarkable horizontal and vertical large-scale patterns in bacterial communities. This opens interesting perspectives for the definition of biogeographical biomes for bacteria of ocean waters and the seabed.
Highlights
Microbes are essential to the ocean in terms of biomass, diversity [1,2,3] and ecosystem functioning [4,5]
The International Census of Marine Microbes (ICoMM) projects whose data have been analysed here employed identical PCR primers, amplification, pyrosequencing and data cleaning and annotation protocols for the very same region of ribosomal RNA genes, which allow for a standardized comparison of the bacterial communities at the global scale
Using 509 selected environmental samples (Fig. 1), the sequence trimming and processing resulted in a total of 9,587,850 DNA sequences related to Bacteria, which clustered into 120,436 Operational Taxonomic Units at 3% sequence dissimilarity level (OTU0.03, Table 1)
Summary
Microbes are essential to the ocean in terms of biomass, diversity [1,2,3] and ecosystem functioning [4,5]. The ocean is the largest contiguous environment on Earth, but it displays a basic subdivision into the pelagic (i.e. water column) and the benthic (i.e. sediment) realms. Both realms differ profoundly in terms of physical, chemical, and biological properties, as well as spatial and temporal scales of variability [3,6]. Marine microbial communities have been essential contributors to global biomass, nutrient cycling, and biodiversity since the early history of Earth, but so far their community distribution patterns remain unknown in most marine ecosystems
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have