engleski

Impact of nautical tourism on copper concentrations in Krka River estuary (Croatia)

Copper (Cu) is a micronutrient required in a number of cellular processes that are key for phytoplankton growth. As phytoplankton is the first level of the food chain, deficiency in copper can lead to numerous unfavourable biological conditions in the sea ecosystem. At physiologically high concentrations, copper is toxic and affects both planktonic abundance and diversity in coastal waters. Range of copper concentrations between these two extremes is relatively narrow [1, 2, 3]. Copper contaminates coastal waters due to anthropogenic input. It is used as an anti- biofouling agent with Cu-based paint covering the hull of boats, releasing considerable quantity in coastal waters. The areas which are potentially endangered are those with high variations of copper concentration and small water exchange rate. One of these areas is the Krka River estuary. Estuary is protected as NATURA 2000 site under name Krka Mouth. Considering the value of Estuary, increased development of nautical tourism poses a threat for this protected area. Preliminary studies carried out in the Krka River estuary in last several years, have showed that during summer season concentrations of copper are up to 20 times higher compared to winter season [4]. Number of vessels (per day/month/year) in Estuary was unknown. To evaluate relation between copper contents in water and the number of vessels during one-year period, a monitoring system has been established, based on the two main activities: (1) setting up of a video surveillance/observing system for vessels counting, (2) monitoring of copper content in surface water. The video observing system provided continuous information about input/output and statistics of the vessels (hour, day, month, year). In surface water samples, which have been collected every 2-3 days in front of Marine station Martinska, concentrations of copper and other trace metals were measured. The established monitoring has confirmed strong relation between the nautical tourism and concentrations of copper in surface layer (Figure 1). Additionally, it was estimated that other factors, such as salinity, the Krka River flow and wind strength and direction have additional influence on temporal copper distribution. The results from this research can be used as support in planning sustainable tourism in this, as well as in other protected areas.

Copper; Krka River estuary; antifouling paints

nije evidentirano