Influence of PAHs among other coastal environmental variables on total and PAH-degrading bacterial communities
Abstract
We evaluated the relative impact of anthropogenic
polycyclic aromatic hydrocarbons (PAHs) among biogeochemical
variables on total, metabolically active, and PAH
bacterial communities in summer and winter in surface
microlayer (SML) and subsurface seawaters (SSW) across
short transects along the NW Mediterranean coast from three
harbors, one wastewater effluent, and one nearshore observatory
reference site. At both seasons, significant correlations
were found between dissolved total PAH concentrations and
PAH-degrading bacteria that formed a gradient from the shore
to nearshore waters. Accumulation of PAH degraders was
particularly high in the SML, where PAHs accumulated.
Harbors and wastewater outfalls influenced drastically and
in a different way the total and active bacterial community
structure, but they only impacted the communities from the
nearshore zone (<2 km from the shore). By using direct multivariate
statistical analysis, we confirmed the significant effect
of PAH concentrations on the spatial and temporal dynamic
of total and active communities in this area, but this effect was putted in perspective by the importance of other
biogeochemical variables