Environmental Impact of the Marine Aquaculture in GÜLLÜk Bay, Turkey

Abstract

The effects of marine aquaculture on the environment were evaluated by studying the water quality of Güllük Bay (Turkey). Marine aquaculture, both extensive and intensive, is one of the most important activities carried out in this area. The intensive culture of fish (Dicentrarchus labrax) is the most important polluting element in Güllük Bay. Records of long term (seasonally) monitoring of the ambient water dissolved oxygen concentration, the inorganic nutrients (ammonia, nitrate, nitrite, and phosphate) and chlorophyll a concentrations were generated to assess sea water quality of Güllük Bay. Surface water (0.5 m) samples were collected from seven fish farm areas in the cage of Güllük Bay (here after reported as the cage stations). Reference surface water was also concurrently sampled at three stations. Modifications in the cage stations water quality were assessed as the difference between the magnitude of a specific parameter recorded at cage station and the concurrently recorded value of the parameter at the reference station, relative to the mean value at the reference station. In this study, results in the specific modifications are discussed at the study period. An aquaculture area had consistently positive modifications in phosphate concentration, but not in nitrogen or chlorophyll a concentrations. Chlorophyll a concentrations showed non positive modifications only in June. In addition to these site specific modifications nitrogen concentrations were positively modified in August and October.

Marine cage culture and the environment: effects on water quality and primary production

“…Overall chlorophyll levels remained low (< 2 µg g −1 ) and, while some variability between farms was evident, there were no de tectable differences between farm and reference sites. Demirak et al (2006) found no difference in chl a level at 7 Turkish fish farm sites compared to reference sites. Similarly, Basaran et al (2010) did not detect a significant difference in chlorophyll concentrations at 8 sea bream and sea bass farms off Turkey compared to a control station.…”

“…The decreased oxygen levels were due to fish respiration and current velocity was sufficient to avoid severe oxygen depletion. A study in Turkey's Güllük Bay (Demirak et al 2006) monitored dissolved oxygen at 7 sea bass cages and 3 control sites. Dissolved oxygen at the cage sites was significantly lower than at control sites, but remained > 4 mg l −1 , a threshold for the onset of stress for many marine fish species.…”

Impacts of the fish farms on the water column nutrient concentrations and accumulation of heavy metals in the sediments in the eastern Aegean Sea (Turkey)

“…However, there is limited number of studies in the eastern Aegean Sea (Demirak et al 2006;Yucel-Gier et al 2007;Kaymakci-Basaran et al 2007). …”

“…However, Demirak et al (2006), who investigated dissolved nutrients in Gulluk Bay (Aegean Sea), observed that major differences in dissolved inorganic nitrogen (DIN) were explained by fish farming activity. They reported that DIN concentrations were significantly higher in summer than in winter due to high production in summer months.…”

Assessment of water quality parameters in the stream Galyan, Trabzon, Turkey

“…The abundance of organic compounds, toxic chemicals, radionuclides, nitrites, and nitrates in potable water may cause adverse effects on the human health (Ikem et al 2002;Tuzen and Soylak 2006;Demirak et al 2006;Marahel et al 2009;Massas et al 2009). Therefore, it is essential to constantly monitor water quality used for drinking purposes (Soylak and Elçi 2000;Virkutyte and Sillanpää 2006;Ghaedi et al 2007Ghaedi et al , 2008Ghorbani et al 2008;Usydus et al 2009;Rauf and Hanan 2009).…”