Using multiple indicators to assess the environmental status in impacted and non-impacted bathing waters in the Iranian Caspian Sea

Human activities have increased in the Caspian Sea in last decades, impacting the coastal zone ecosystems. One of the increasing activities is recreation, including bathing areas in the south of the Caspian Sea, which have been scarcely studied and assessed. Investigating the interactions between human activities and the resulting environmental status in bathing areas, by using adequate indicators and assessment methods, is necessary to undertake management measures for ecosystem restoration. In this study, for the first time, we use the Nested Environmental status Assessment Tool (NEAT) outside the European waters to assess environmental status in bathing waters, to differentiate areas impacted and non-impacted by bathing activities. We have assessed the status in winter and summer seasons, by combining multiple indicators from different ecosystem components (8 physico-chemical, 4 bacteria, 2 plankton, and 1 benthos indicators). Despite the interactions between season and human affection, NEAT determined that the Caspian Seas is not in good status, differentiating, in summer, between impacted and non-impacted bathing areas, with a significant correlation with the number of beach users. Accordingly, management measures should be taken in the southern Caspian Sea to improve the environmental status in general and that of bathing areas in particular.