Phytoplankton cells in estuary waters usually experience drastic changes in chemical and physical environments due to mixing of fresh and seawaters. In order to see their photosynthetic performance in such dynamic waters, we measured the photosynthetic carbon fixation by natural phytoplankton assemblages in the Jiulong River estuary of the South China Sea during April 24–26 and July 24–26 of 2008, and investigated its relationship with environmental changes in the presence or the absence of UV radiation. Phytoplankton biomass (Chl a) decreased sharply from the river-mouth to seawards (17.3–2.1μgL⁻¹), with the dominant species changed from chlorophytes to diatoms. The photosynthetic rate based on Chl a at noon time under PAR-alone increased from 1.9μgC (μg Chl a)⁻¹L⁻¹ in low salinity zone (SSS<10) to 12.4μgC (μg Chl a)⁻¹L⁻¹ in turbidity front (SSS within 10–20), and then decreased to 2.1μgC (μg Chl a)⁻¹L⁻¹ in mixohaline zone (SSS>20); accordingly, the carbon fixation per volume of seawater increased from 12.8 to 149μgCL⁻¹h⁻¹, and decreased to 14.3μgCL⁻¹h⁻¹. Solar UVR caused the inhibition of carbon fixation in surface water of all the investigated zones, by 39% in turbidity area and 7–10% in freshwater or mixohaline zones. In the turbidity zone, higher availability of CO₂ could have enhanced the photosynthetic performance; while osmotic stress might be responsible for the higher sensitivity of phytoplankton assemblages to solar UV radiation.

Inverted microscopy is widespread employed for the analysis of phytoplankton composition within water quality monitoring networks. However, the analysis at the lowest taxonomical level is not always required for ecological status assessment. In addition, inverted microscopy can underestimate the small phytoplankton, and not always distinguish photoautotrophic from heterotrophic cells. In this study, as alternative tools, epifluorescence microscopy and High Performance Liquid Chromatography (HPLC) were employed to characterize phytoplankton communities within waters of different trophic condition. Epifluorescence microscopy confirmed its effectiveness to count the small phytoplankton. Furthermore, significant correlations between nutrients of anthropogenic origin and nanoplankton abundances were found. However, this technique resulted very time-consuming. HPLC together with the CHEMTAX program was more appropriate than inverted microscopy, in terms of cost-effectiveness. Also, the main variability patterns observed in the phytoplankton community structure by HPLC coincided with previous findings in the study area. Nevertheless, a rapid screening at the inverted microscope is recommended.

When nutrients impact estuarine water quality, scientists and managers instinctively focus on quantifying and controlling land-based sources. However, in Greenwich Bay, RI, the estuary opens onto a larger and more intensively fertilized coastal water body (Narragansett Bay). Previous inventories of nitrogen (N) inputs to Greenwich Bay found that N inputs from Narragansett Bay exceeded those from the local watershed, suggesting that recent efforts to reduce local watershed N loads may have little effect on estuarine water quality. We used stable isotopes of N to characterize watershed and Narragansett Bay N sources as well as the composition of primary producers and consumers throughout Greenwich Bay. Results were consistent with previous assessments of the importance of N inputs to Greenwich Bay from Narragansett Bay. As multiple N sources contribute to estuarine water quality, effective management requires attention to individual sources commensurate with overall magnitude, regardless of the political complications that may entail.

Concentrations of Zn, Cd and Pb were measured in muscle of pelagic, demersal and benthic fishes, captured in the coastal area adjoining the Tagus estuary (Portugal), in 1998 and 2010. Additionally, Pb and Cd were determined in estuarine waters, showing a pronounced decrease between 1999 and 2010. Accordingly, specimens captured in 2010 presented significantly lower metal concentrations than individuals caught in 1998. Reductions were more evident for Pb (reduction of 59–99%) than for Cd (14–93%) and Zn (17–54%). Values in pelagic and demersal species exhibited higher reductions than in benthic species. Decrease of metal concentrations in fish appears thus to reflect the improvement of estuarine water quality as anthropogenic sources have been reduced or eliminated. Furthermore, it emphasises the usefulness of the descriptor “Contaminants in Fish” to assess the efficiency of measures to achieve a good environmental status, in the scope of the Marine Strategy Framework Directive.

One of the aims of the Water Framework Directive 2000/60/CE is to assess the ecological status of water bodies in Europe in relation to priority contaminants, including some persistent organic pollutants (POPs). Recognizing the benefits of measuring hydrophobic compounds in biota tissues rather than in water, we used the European eel Anguilla anguilla in the present study as a bioindicator species for monitoring POPs in freshwater/brackish environments. We present the results of a contamination analysis of eels carried out in three Italian sites representative of different pollution levels: the last part of Tevere River, which flows through a very urbanized and industrialized area, Caprolace Lake and Lesina Lagoon, inside two different protected national parks. A very high pollution variability was recorded within each group of eels, in particular for those caught at Caprolace Lake. Due to this high variability, inter-population comparisons were carried out only between eels collected in Tevere River and Lesina Lagoon. PCBs values in Lesina Lagoon were two orders of magnitude lower than those measured in Tevere River, while no significant differences were found for levels of DDT compounds. Our results confirm the suitability of the eel as an indicator of persistent bioaccumulative pollutants in brackish environments and rivers where it can be easily caught, but we are sceptical of its use in deep lakes where its capture might be problematic considering standard operation procedures for fish sampling.

Coastal lands around Bay of Bengal in Central Godavari Delta are mainly agriculture fields and two times annually paddy crops putting in the study area. Canals of Godavari River are the main source of water for irrigation. Geophysical and geochemical investigations were carried out in the study area to decipher subsurface geologic formation and assessing seawater intrusion. Electrical resistivity tomographic surveys carried out in the watershed-indicated low resistivity formation in the upstream area due to the presence of thick marine clays up to thickness of 20–25 m from the surface. Secondly, the lowering of resistivity may be due to the encroachment of seawater in to freshwater zones and infiltration during tidal fluctuation through mainly the Pikaleru drain, and to some extent rarely through Kannvaram and Vasalatippa drains in the downstream area. Groundwater quality analyses were made for major ions revealed brackish nature of groundwater water at shallow depth. The in situ salinity of groundwater is around 5,000 mg/l and there is no groundwater withdrawal for irrigation or drinking purpose in this area except Cairn energy pumping wells which is using for inject brackish water into the oil wells for easy exploration of oil. Chemical analyses of groundwater samples have indicated the range of salt concentrations and correlation of geophysical and borehole litholog data in the study area predicting seawater-contaminated zones and influence of in situ salinity in the upstream of study area. The article suggested further studies and research work that can lead to sustainable exploitation/use and management of groundwater resources in coastal areas.