Coastal Anthropogenic Activities

Furthermore, with respect to artificial bait, which is primarily applied in shrimp mariculture and cage culture nowadays, bait feeding is an important factor affecting the marine environment. Approximately 20% of the baits are 

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Abstract. Starting with 70ies, Romanian Black Sea shore is confronting with marine eutrophication, as a result of nutrients input from sources such as the Danube River and coastal anthropogenic activities. Due to economical decline in early 90ies, the effects of eutrophication (phytoplankton blooms, fauna mortalities) have had low occurrence. 

The most intense period of eutrophication at the Romanian Black Sea shore were the 70ies and 80ies. The Danube river and coastal anthropogenic activities were the main sources of nutrients. Once the intensity of economic activities decreased (early 90ies), the marine environment is slowly evolving toward a normal status, some parameters of the marine biota (biomass and diversity) indicating the improving trend. 

Inputs of new N into coastal systems are more diverse than inputs to the open ocean and include compounds considered regenerated N sources in the open ocean. New N can be dehvered by rivers, runoff events, and atmospheric deposition and can include a whole spectrum of N compounds including NH4 , urea, and DON (e.g., Anderson et al., 2002 Glibert et al., 2001, 2005c MuIhoUand et al., 2007). Similarly NH4 derived from natural processes and anthropogenic activities can support new production in estuarine and coastal systems (see Chapter 9 by Seitzinger and Harrison and Chapter 11 by Paerl and Piehler, this volume). 

Methods for correcting for grain-size effects in studies on heavy metal concentrations in estuarine and coastal sediments have been discussed by Ackermann (1980). There is, unfortunately, no one standard method for particle-size normalisation and a wide range of techniques are in use (Table 2.3). The method which often involves the least effort is the correction which uses comparison with rubidium (Rb) as a conservative element (Ackermann, 1980). This technique relies on the fact that Rb has a similar ionic radius to potassium (K) and so substitution of Rb for K will take place in clay minerals. Furthermore, Rb is present in the sand fraction in very much smaller concentrations than in the clay or silt fraction and concentrations of the element in sediments are rarely influenced by anthropogenic activity. Another advantage of the use of Rb is that it is often routinely analysed by X-ray fluorescence along with a suite of pollutant trace metals. 

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