11 research outputs found
Evidence of niche partitioning among bacteria living on plastics, organic particles and surrounding seawaters
Plastic pollution is widespread in ocean ecosystems worldwide, but it is unknown if plastic offers a unique habitat for bacteria compared to communities in the water column and attached to naturally-occurring organic particles. The large set of samples taken during the Tara-Mediterranean expedition revealed for the first time a clear niche partitioning between free-living (FL), organic particle-attached (PA) and the recently introduced plastic marine debris (PMD). Bacterial counts in PMD presented higher cell enrichment factors than generally observed for PA fraction, when compared to FL bacteria in the surrounding waters. Taxonomic diversity was also higher in the PMD communities, where higher evenness indicated a favorable environment for a very large number of species. Cyanobacteria were particularly overrepresented in PMD, together with essential functions for biofilm formation and maturation. The community distinction between the three habitats was consistent across the large-scale sampling in the Western Mediterranean basin. 'Plastic specific bacteria' recovered only on the PMD represented half of the OTUs, thus forming a distinct habitat that should be further considered for understanding microbial biodiversity in changing marine ecosystems
Biogeochemical cycling and phyto- and bacterioplankton communities in a large and shallow tropical lagoon (Términos Lagoon, Mexico) under 2009–2010 El Niño Modoki drought conditions
The 2009–2010 period was marked by an episode of intense drought known as
the El Niño Modoki event. Sampling of the Términos Lagoon (Mexico) was
carried out in November 2009 in order to understand the influence of these
particular environmental conditions on organic matter fluxes within the
lagoon's pelagic ecosystem and, more specifically, on the relationship between
phyto- and bacterioplankton communities. The measurements presented here
concern biogeochemical parameters (nutrients, dissolved and particulate
organic matter [POM], and dissolved polycyclic aromatic hydrocarbons [PAHs]),
phytoplankton (biomass and photosynthesis), and bacteria (diversity and
abundance, including PAH degradation bacteria and ectoenzymatic activities).
During the studied period, the water column of the Términos Lagoon functioned
globally as a sink and, more precisely, as a nitrogen assimilator. This was due to
the high production of particulate and dissolved organic matter (DOM), even though
exportation of autochthonous matter to the Gulf of Mexico was weak. We found
that bottom-up control accounted for a large portion of the variability of
phytoplankton productivity. Nitrogen and phosphorus stoichiometry mostly
accounted for the heterogeneity in phytoplankton and free-living prokaryote
distribution in the lagoon. In the eastern part, we found a clear decoupling
between areas enriched in dissolved inorganic nitrogen near the
Puerto Real coastal inlet and areas enriched in phosphate (PO4) near
the Candelaria estuary. Such a decoupling limited the
potential for primary production, resulting in an accumulation of dissolved
organic carbon and nitrogen (DOC and DON, respectively) near the river
mouths. In the western part of the lagoon, maximal phytoplankton development
resulted from bacterial activity transforming particulate organic phosphorus (PP) and dissolved organic
phosphorus (DOP) to available PO4 and the coupling between Palizada River inputs of nitrate
(NO3) and PP. The Chumpan River contributed only
marginally to PO4 inputs due to its very low contribution to overall
river inputs. The highest dissolved total PAH concentrations were measured
in the El Carmen Inlet, suggesting that the anthropogenic pollution of the zone is
probably related to the oil-platform exploitation activities in the shallow
waters of the southern of the Gulf of Mexico. We also found that a complex
array of biogeochemical and phytoplanktonic parameters were the driving
force behind the geographical distribution of bacterial community structure
and activities. Finally, we showed that nutrients brought by the Palizada
River supported an abundant bacterial community of PAH degraders, which are
of significance in this important oil-production zone