Are there concerns regarding cHAB in coastal bathing waters affected by freshwater-brackish continuum?

Toxic cyanobacterial blooms, their prevalence in freshwaters, and their impact on water quality are well documented. In contrast, the impact on the recreational value of bathing sites of the cyanotoxin-contaminated inland waters, transported to estuarine and coastal marine waters, has been less frequently studied. The aim of this work was to assess water quality at bathing sites located in the southern Baltic Sea and the Curonian Lagoon, using cyanotoxins concentrations as an indicator. Our results showed that higher diversity and concentrations of cyanotoxins in some areas of the coastal zone are related to the transport of waters from the Curonian Lagoon. The studied bathing sites had a relatively low probability of adverse health effects, with a potential higher risk in the southern part of the Curonian Lagoon (Lithuania). Due to the observed changes in the cyanobacteria community, the determination of cyanotoxins concentrations, irrespective of the analysis of cyanobacteria, is recommended.

Fecal contamination in shallow temperate estuarine lagoon: Source of the pollution and environmental factors.

In inner coastal waters such as lagoons, which are very turbid and rich in suspended particles, the survival of fecal pollution microorganisms may find favorable environments. In order to better characterize the sources and dynamics of fecal pollution in a strongly turbid environment, in situ observations were made in the Curonian Lagoon. A combination of traditional monitoring and molecular methods were used. To monitor the water quality, the indicator Escherichia coli (EC) was selected as a proxy for fecal contamination. E. coli concentration correlated with environmental parameters as pH, oxygen and turbidity. The main pollution sources are the sewage outlets in the lagoon area, while the pollution coming via rivers did not play a significant role. Still the human associated E. coli consisted only of 0 up to 20% of analyzed isolates, and did not correlate with the E. coli concentrations in the study sites. The role of birds, especially for potentially virulent E. coli may be underestimated in the lagoon.