Benthic Prokaryotic Community Response to Polycyclic Aromatic Hydrocarbon Chronic Exposure: Importance of Emission Sources in Mediterranean Ports

Francesco Vitali,Simona Sergi,Christos Arvanitidis,Raffaela Lussu,Manolis Mandalakis,Giorgio Mastromei,Thanos Dailianis,Enrico Casalone,Elena Tamburini,Eva Chatzinikolaou,Giuliana Senatore

doi:10.3389/fmars.2019.00590

Abstract

The present study aimed to evaluate the impact of polycyclic aromatic hydrocarbons (PAHs) produced by multiple emission sources on prokaryotic communities in sediments chronically affected by anthropogenic pressures. In this context, surface sediments were investigated in three Mediterranean touristic ports over three sampling periods and in different port sectors. The levels of 16 priority PAHs varied over three orders of magnitude (25-49,000 ng g-1) covering the range of concentrations previously reported for Mediterranean harbors. Pyrogenic processes were found to be the dominant emission source of PAHs, with considerable differences among ports. The prokaryotic communities were identified by using the terminal restriction fragment length polymorphism, targeting the 16S rRNA gene for Bacteria and Archaea as well as the dsrAB gene for sulphate-reducing bacteria (SRB). The structure of the three benthic prokaryotic communities varied consistently among the ports. The structure of Bacteria and Archaea exhibited strong spatiotemporal variations that did not allow us to specifically link the observed differences in community structures with PAH sources. On the contrary, our study provided, for the first time, evidence that the PAH emission sources play a role in structuring benthic communities of sulphate-reducing bacteria (SRB). Our findings indicate that the SRB community can be used as a valuable candidate biotic descriptor for bioremediation monitoring in heavily impacted port sediments.

Highlights

Pollution by polycyclic aromatic hydrocarbons (PAHs) remains one of the major threats to marine ecosystems and human health due to their toxic, carcinogenic and mutagenic properties (Ghosal et al, 2016)
The present study aimed to evaluate the impact of polycyclic aromatic hydrocarbons (PAHs) produced by multiple emission sources on prokaryotic communities in sediments chronically affected by anthropogenic pressures
In sediments collected from El Kantaoui, sum of 16-Environmental Protection Agency (EPA) priority PAHs (16PAH) concentrations ranged from 25 ng g−1 at the port entrance (E3) to 367 ng g−1 near the fuel station (E2) and pollution was classified as “low” (0–100 ng g−1) and “moderate” (100–1,000 ng g−1), respectively, according to the categories determined by Baumard et al (1998)

Summary

Introduction

Pollution by polycyclic aromatic hydrocarbons (PAHs) remains one of the major threats to marine ecosystems and human health due to their toxic, carcinogenic and mutagenic properties (Ghosal et al, 2016). The ubiquitous distribution of PAHs in coastal environments has been mainly attributed to anthropogenic activities (Crain et al, 2009) Because of their hydrophobic nature, PAHs are quickly adsorbed onto suspended particulate material and settle on benthos, sediments represent a sink for these pollutants. The chemical class of PAHs comprises numerous compounds with two or more fused aromatic rings, characterized by diverse physical, chemical and biological properties. Their recalcitrance toward biodegradation as well as their genotoxicity rise with the number of aromatic rings, while volatility and acute toxicity tend to increase with decreasing molecular weight (Ghosal et al, 2016). The relative content of PAHs can vary considerably depending on their origin, namely petrogenic and pyrogenic emission sources (Baumard et al, 1998)

Methods

Results

Discussion

Conclusion