Macrobenthic intertidal assemblages from five Atlantic Iberian estuaries were analyzed to develop an estuarine index. An R-mode analysis revealed a close association between the isopod Cyathura carinata, the polychaete Hediste diversicolor and the bivalve Scrobicularia plana. Although these species are abundant in all the estuaries considered, they tend to be absent from sites at the marine and freshwater ends of the environmental gradient. Three different ways of calculating the estuarine index are proposed. The index is comprised in the interval [0,1] and was constructed using relative abundances rather than absolute abundances. Transformation of the raw data helped improve the performance of the index. A non-parametric statistical test is proposed for application to the estuarine index to find sites with the same values after a significant omnibus test. The index appears to be a good proxy for recognizing estuarine limits by use of indicator species.

Sediment contamination poses a potential risk for both ecosystems and human health. Risk assessment is troublesome as sediments contain complex mixtures of toxicants, and traditional chemical analyses can neither provide information about potential hazards to organisms nor identify and measure all present contaminants. This work combines the use of the PLHC-1 cell line and the recombinant yeast assay (RYA) to assess the environmental quality of estuarine and coastal sediments. The application of multiple endpoints (cytotoxicity, generation of oxidative stress, presence of CYP1A inducing agents, micronucleus formation and estrogenicity) revealed that the organic extracts of those sediments affected by industrial activities or collected near harbours and untreated urban discharges showed significant cytotoxicity, micronuclei and CYP1A induction. The study highlights the usefulness of the applied bioassays to identify those sediments that could pose risk to aquatic organisms and that require further action to improve their environmental quality.

We investigated the spatial scales of variation of macrofauna in intertidal flats subjected to different levels of contamination from urban effluents in two areas sampled in the Paranaguá Estuarine Complex. The scales considered were: Conditions; Tidal flats and Plots. Although the numerically dominant taxa showed the greatest variability at a scale of Tidal flats, the variability at the Condition scale was also significant. Tubificinae sp. 1, Laeonereis culveri and Heteromastus sp. were the most abundant organisms in the Contaminated area, while Heleobia australis was most abundant in the Non-contaminated area. Our results, contrary to those frequently observed in the literature, showed that the variability was significant at the scale of hundreds of metres (Tidal flats). At this scale, the intrinsic characteristics of each tidal flat are more important in determining macrofaunal distribution, while the effects of the urban sewage contamination represent the primary forces acting at a greater spatial scale.

The Arabian Gulf is considered among the highest anthropogenically impacted regions in the world. Heavy metals contamination in coastal and marine environments is becoming an increasingly serious threat to both the naturally stressed marine ecosystems and humans that rely on marine resources for food, industry and recreation. Heavy metals are introduced to coastal and marine environments through a variety of sources and activities including sewage and industrial effluents, brine discharges, coastal modifications and oil pollution. The present paper reviews heavy metal contamination in a variety of marine organisms, and sediments, and suggests measures for environmental management of heavy metal pollution in the Arabian Gulf. Most of the reviewed literature confirmed that heavy metal concentrations in marine organisms were generally within allowable concentrations and pose no threat to public health. Likewise, studies suggested that levels of heavy metals in marine sediments are similar or lower compared to other regions. However, localized hotspots of chronic metal pollution in areas influenced by industrial facilities, desalination plants, and oil refineries have been reported. Holistic spatial and temporal monitoring and comprehensive national and regional strategies are critical to combat and manage heavy metal pollution in the Arabian Gulf.

Pharmaceuticals are common chemical contaminants in estuaries receiving effluent from wastewater and sewage treatment facilities. The purpose of this research was to examine benthic microalgal (BMA) community responses to sublethal exposures to tylosin, a common and environmentally persistent antibiotic. Bioassays, using concentrations of 0.011–218μmoltylosinl−1, were performed on intertidal muddy sediments from North Inlet Estuary, SC. Exposure to tylosin resulted in a reduction in total BMA biomass and primary productivity. Furthermore, exposure seemed to retard diatom growth while having a minimal effect on cyanobacteria biomass. Estuarine systems receiving chronic inputs of trace concentrations of tylosin, as well as other antibiotics, may experience significant reductions in BMA biomass and primary productivity. Given the well-documented role of BMA in the trophodynamics of estuaries, these impacts will likely be manifested in higher trophic levels with possible impairments of the structure and function of these sensitive systems.

This study focused on the spatial distribution of trace metals in the Veracruz Reef System in the Southern Gulf of Mexico, and its variability in the early (July) and late (September) rainy season of 2008, by analyzing the concentration of Cd, Cu and Pb in benthic macroalgae. Mean concentrations are lower (Pb 295±347ngg−1, Cd 17.9±15.0ngg−1), or similar (Cu 3.4±4.5μgg−1) to those reported from other coastal areas. Cd and Pb concentrations are influenced by the discharge of the Jamapa River, evidencing a fluvial control on coastal trace metal levels. Also, Cd and Cu concentrations were lower in the late rainy season, when there is a high load of suspended sediments derived from fluvial discharge, which probably adsorb dissolved metals decreasing their bioavailability. Pb concentrations have been decreasing in the last two decades in the SGM, after the banning of leaded-gasoline in the late 20th century.

The paper detailed a water quality modelling study of a hyper-tidal estuary, undertaken to assess the impact of various bacteria input loads on the receiving waters in a coastal basin in the UK, by using the model developed in previous study of the same authors enterococci, used as the indicators for bathing water quality under the new European Union (EU) Bathing Water Directive, were numerically modelled using a hydro-environmental model. In particular, the numerical model used in this study includes the effects of sediment on bacteria transport processes in surface water. Finally, the importance of sediment bacteria inputs on the bathing water quality was also investigated under different weather and tidal condition. During spring tide, the bacteria input from the bed sediments are dominant for both wet and dry weather conditions. During neap tides and during dry weather conditions the inputs of bacteria from the bed sediment were still dominant, but during wet weather conditions the inputs from river were dominant. Under different tidal flow conditions some parameters had a more significant role than others. During high flow conditions the sediment re-suspensions processes were dominant, therefore the bed bacteria concentrations played a dominant role on the overall bacteria concentration levels in the water column. In contrast, during low flow conditions sediment deposition prevails and bacteria are removed from the water column. The partition coefficient was found to be more important than the bed bacteria concentrations, during low flow conditions.

The Berre lagoon receives freshwater from two natural rivers but the implementation of the hydroelectric power plant led to strong changes in the ecosystem structure and functioning. Sediments are important sites for nitrogen cycling because the O2 sharp gradient allows oxic nitrification as well as anoxic denitrification and anammox to operate in close proximity. Seasonal and short-term variations in the coastal nitrogen processes were quantified at two stations: SA1 located in the northern part of the lagoon directly under the inflows of freshwater and SA3 in the southern part of the lagoon influenced mainly by the marine water inflows. Results revealed that most of the nitrate formed by nitrification was denitrified. Total denitrification was the main N2 removal process. The high primary production based on N–NH4+ might be explained by mineralization rates, while the primary production based on N–NO3- was not fully explained by nitrification.

The increasing risks of potential oil spills in the arctic regions, which are characterized by low temperatures, are a big challenge. The traditional dispersant method has shown limited effectiveness in oil cleanup. This work studied the role of mineral fines in the formation of oil–mineral aggregates (OMAs) at low temperature (0–4°C) environment. The loading amount of minerals and dispersant with different dispersant and oil types were investigated under a full factorial design. The shapes and sizes of OMAs were analyzed. Results showed that the behavior of OMA formation differs when dispersant and mineral fines are used individually or together. Both the experimental and microscopic results also showed the existence of optimal dispersant to oil ratios and mineral to oil ratios. In general, poor oil removal performance was observed for more viscous oil. Corexit 9500 performed better than Corexit 9527 with various oils, in terms of oil dispersion and OMA formation.

The surface sediments from Laizhou Bay (LB) and the coastal sea around Zhangzi Island (ZI) were analyzed for acid-volatile sulfide (AVS) and simultaneously extracted metals (SEMs) to assess the sediment quality. These two areas, especially LB, are important mariculture bases in China and are significantly affected by the Yellow River. The concentrations of AVS ([AVS]) and SEM ([SEM]) varied in the ranges 0.71–11.03 and 0.10–0.74μmolg−1 dry weight, respectively. [AVS] was generally low in the river outlet area and increased in the seaward direction in LB. [AVS] was significantly and positively correlated with TOC. [SEM] was significantly and positively correlated with TOC, the water content of sediment and the fine sediment fraction and it was significantly and negatively correlated with coarse sediment fraction. The obtained results suggest that the surface sediments of LB and ZI were of high quality and not likely to cause negative effects on their ecosystems.