Native mussels Mytilus galloprovincialis are used as bioindicator organisms to assess the concentration levels and toxic effects of persistent chemicals, polychlorobiphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and heavy metals using biomarker responses, such as catalase (CAT), glutathione s-transferase (GST), and condition indices, for the Algerian coast. The results show that mussels of Oran Harbour are extremely polluted by PCBs and PAHs, i.e., 97.6 and 2892.1μg/kg d.w., respectively. Other sites present low levels of pollution. Furthermore, high concentrations of zinc, lead and cadmium are found in mussels from fishing, agricultural and estuarine sites, respectively, while low concentrations of copper are found in all of the sites studied. CAT activity is negatively correlated with Cd and Cu, and Zn is positively correlated with GST and CAT. Site classification tools reveal the potential toxicity of coastal areas exposed to anthropogenic pressure and a gradient of toxicity along the Algerian west coast.

Occurrence of algal blooms in coastal waters is predicted to be more prevalent in future. To minimize their occurrence, manipulating the grazing pressure by suspension feeders is a potential management strategy, but its effectiveness may depend on their feeding preference. Therefore, we assessed the clearance rate of a widespread serpulid polychaete Hydroides elegans in larval and adult stages on various coastal phytoplankton. Additionally, the growth and development of H. elegans after consuming these phytoplankton were determined to reflect its sustainability to counter algal blooms. Results showed that H. elegans can consume and utilize different phytoplankton, except diatom Thalassiosira pseudonana, for growth and development in both life stages. Given the fast-colonizing ability which allows easy manipulation of abundance, H. elegans is considered practically and biologically ideal for tackling algal blooms. Other suspension feeders with different feeding niches could be used in combination to maximize the versatility of the top-down control.

The production of melanin is a complex process involving biochemical cascades, such as the pro-phenoloxidase (proPO) system, and enzymes, such as phenoloxidases (POs). Different studies have shown a strong correlation between the decrease in PO activities and the occurrence of diseases in bivalve invertebrates, leading to mortalities in the host. Results of these studies suggest that POs could play a fundamental role in defense mechanisms in bivalves. This article reviews the fundamental knowledge on the proPO system in bivalves and the methods used to assess PO activities. Finally, this is the first report on the major findings of laboratory and field studies that indicate that a type of PO in bivalves, the laccase enzyme, is inducible and involved in the 1) immune 2) antioxidant and 3) detoxification roles in bivalves, and might be an ecological potential biomarker of environmental stress.

Phytoplankton assemblages related to environmental factors and ecological status of the Gemlik Gulf were investigated between June 2010 and May 2011. A total 155 phytoplankton species were detected and 6 taxa (Amphisolenia laticincta, Archaeperidinium minutum, Cochlodinium sp., Gynogonadinium aequatoriale, Heterocapsa rotundata and Metaphalacroma sp.) were new records for the Turkish Seas. The lowest and highest total phytoplankton abundance among the sampling units (depths) was recorded in April 2011 (7.4×103cellsL−1) and July 2010 (251.8×103cellsL−1). Local small patches of visible red tide events were detected especially in the gulf, although a phytoplankton bloom was not observed. The water column was well stratified in the early autumn and well mixed in the early spring according to stratification index values. Surface nutrient concentrations increased especially at stations located inside of the gulf. The limiting effect of silicate was observed in early, mid-summer and early winter periods while the nitrogen was the limiting nutrient in the gulf during the whole sampling period. In the Gulf, low water quality-high mesotrophic and bad water quality-eutrophic status, high quality and low trophic level were generally detected according to Chl a, dissolved oxygen and trophic index. However, indices developed to determine the trophic level and water quality of the Mediterranean Sea can give unexpected results about the current environmental quality status when it is applied to the Marmara Sea which has limited photic zone by the halocline-pycnocline and thermocline.

An in situ particle imaging system for measurement of high concentrations of suspended particles ranging from 30μm to several mm in diameter, is presented. The system obtains quasi-silhouettes of particles suspended within an open-path sample volume of up to 5cm in length. Benchmarking against spherical standards and the LISST-100 show good agreement, providing confidence in measurements from the system when extending beyond the size, concentration and particle classification capabilities of the LISST-100. Particle-specific transmittance is used to classify particle type, independent of size and shape. This is applied to mixtures of oil droplets, gas bubbles and oil-coated gas bubbles, to provide independent measures of oil and gas size distributions, concentrations, and oil-gas ratios during simulated subsea releases. The system is also applied to in situ measurements of high concentrations of large mineral flocs surrounding a submarine mine tailings placement within a Norwegian Fjord.

Persistent organic pollutants (POPs) are dispersed all over the world while polycyclic aromatic hydrocarbons (PAHs) are released into the environment from pyrogenic and petrogenic sources and are not very mobile or persistent. The aim of this study was to identify POPs and PAHs from eggs of Least and Sooty Terns nesting in two protected marine areas with different anthropogenic impacts in the southern Gulf of Mexico. ΣHCHs were higher in Terminos in 2010 and higher in Alacranes in 2011. ΣDienes and ΣDDTs were higher in 2011 in both study sites. ΣEndosulfan was higher in Terminos than in Alacranes in both years. ΣDienes, ΣDDT and ΣHeptachlor were the highest in both species both years. Acenaphtylene and Fluoranthene were higher in Terminos while Pyrene was higher in Alacranes. No differences were present within species between years. In 2011 PAHs in eggs could have reflected the BP oil spill input.

In this study, the 16S rRNA-based Illumina MiSeq sequencing was used to investigate the bacterial community structure and composition of intertidal biofilm taken along the Yangtze Estuary. The results showed that 680,721 valid sequences of seven samples were assigned to 147,239 operational taxonomic units, which belonged to 49 phyla, 246 family and 314 genera. Compared to other studies on water and sediments in the study area, biofilms showed highest index of bacterial diversity and abundances. At different taxonomic levels, both dominant taxa and their abundances varied among the seven samples, with Proteobacteria as the dominant phylum in general. Principal component analysis and cluster analysis revealed that bacterial communities at WSK differed from those at other sampling sites. Salinity, dissolved oxygen, pH and nutrients were the vital environmental factors to influence the bacterial community structure of biofilms. These results may provide a new insight into the microbial ecology in estuarine environments.

This field study is intended to propose a global methodology to assess and monitor the water quality of the gulf of Morbihan, a littoral ecosystem under increasing anthropic pressure. To this end, the Locmariaquer site, where Crassostrea gigas is extensively cultivated, was selected to perform a one-year follow-up of tissular glutathione S-transferase and acetylcholinesterase specific activities in this filter feeder organism. Calculation of an integrated index, corresponding to the ratio of the two enzymes activities, allowed to discriminate from the environmental noise, several clusters which could be representative environmental stress, potentially latent pollution. Moreover, the estrogenic activity was assessed in water samples collected at Locmariaquer and other strategic sites of the gulf. The results evidenced a low estrogenic-disrupting compound contamination of waters. Overall, this methodology produced an accurate outlook of a basal state for the gulf and could be developed in the context of a chronic monitoring of this site.

Constructed mangrove wetland has been used for wastewater treatment but its long-term performance has not been reported. One-year monitoring of a 10-years old horizontal subsurface-flow constructed mangrove wetland consisting of three belts, two with mangrove plants and one without, revealed that the system maintained high and stable removal percentages of organic matter and nutrients, and planted belts performed better than unplanted control. Substrates in belts planted with Aegiceras corniculatum or Kandelia obovata had higher abundance of ammonifiers, nitrifiers and denitrifiers but lower total heterotrophic bacteria than unplanted substrate. Denaturing gradient gel electrophoresis showed that microbial diversity in planted substrate was significantly lower than that in unplanted one. The bacteria in substrates, irrespective to belts, were phylogenetically related to Proteobacteria (most dominant), Acidobacteria, Firmicutes, Nitrospirae, Gemmatimonadetes, Chloroflexi and Cyanobacteria. The steady performance of this 10-year old constructed mangrove wetland was affected by the abundance and diversity of bacterial community in substrate.

Biotic indices for monitoring marine ecosystems are mostly based on the analysis of benthic macroinvertebrate communities. Due to their high sensitivity to pollution and fast response to environmental changes, bacterial assemblages could complement the information provided by benthic metazoan communities as indicators of human-induced impacts, but so far, this biological component has not been well explored for this purpose. Here we performed 16S rRNA gene amplicon sequencing to analyze the bacterial assemblage composition of 51 estuarine and coastal stations characterized by different environmental conditions and human-derived pressures. Using the relative abundance of putative indicator bacterial taxa, we developed a biotic index that is significantly correlated with a sediment quality index calculated on the basis of organic and inorganic compound concentrations. This new index based on bacterial assemblage composition can be a sensitive tool for providing a fast environmental assessment and allow a more comprehensive integrative ecosystem approach for environmental management.