Chlorophyll-a (Chl-a), as an indicator of phytoplankton biomass, carries out the photosynthesis, by which primary organic matter is introduced into the food chain. Organic matter produced in the euphotic zone, is degraded by bacterial activity, depletes oxygen essential for aquatic life. This indicator is also regarded as an indicator of eutrophication.
Laboratory, Measurement and Monitoring Department of the Ministry of Environment and Urbanization implemented “Integrated Marine Pollution Monitoring Programme” with the coordination of TUBITAK-Marmara Research Center. In the programme, quality and pollution are assessed through various indicators in all of seas of Turkey: Mediterranean Sea, Aegean Sea, Black Sea and Marmara Sea.
Marine pollution and quality are assessed in Coastal Water Bodies (CWB). Coastal Water Bodies or in other words Water Management Unit defines a surface water section, which has been separated according to their typologies that are being determined according to physical, hydromorphological, ecological properties and pressures. They are considered as the smallest management units dealt by WFD.
2014-2017 Chl-a assessments showed that all marine waters of Turkey have sufficient solarination. Peak values of Chl-a concentrations occur due to primary production in winter seasons when land based nutrient loads increase. Besides this, no significant difference is observed among years during 2014-2017 monitoring period.
In Mediterranean Sea, in Graph 43, in general, relatively higher chlorophyll-a values were observed in shallow and less salty coastal areas under the effects of rivers and other terrestrial inputs like urban wastewaters (AKD01: Asi River, AKD04: Ceyhan River, AKD05: Seyhan River) where almost all winter concentrations were higher than the summer values. Chlorophyll-a was observed to decrease to its natural level in open sea surface waters where the effects of land-based inputs diminish and in clean coastal areas (the area between Anamur and Marmaris). The inputs were more effective in the upper 5-10 meters of the water column. The changes in the 2017 summer values with depth revealed a similar distribution to the oxygen profiles. While the coastal areas of Mersin and İskenderun gulfs fed by rivers with less salty waters and low SDD values were observed to have high levels of Chl-a; the surface waters of coastal areas where the effect of land-based inputs diminished and the reference conditions were observed to have the natural open sea levels of Chl-a, displaying typical eastern Mediterranean properties.
In Aegean Sea the evaluation of the 2014-2017 surface layer chlorophyll-concentrations at CWBs revealed no significant variation between the summer and winter periods; while relatively high values were observed in the Inner and Central Gulf of İzmir and in the Gulf of Güllük (Graph 44). The relatively high values in the Northern Aegean Sea in winter months might be the result of the Marmara Sea inputs and winter mixing causing nutrient enrichment of the surface waters.
The 2017 summer period surface distributions of the chlorophyll-a, reveal that the concentration across the Black Sea is <1 μg/L (Graph 45). Relatively higher values (>1-1.5 μg/L) were observed generally at the near-coastal stations in the Eastern Black Sea. All of the stations in the open sea revealed values <1 μg/L. The highest chlorophyll-a value was measured at TRK61 station. The comparison of the 2014-2017 data from the CWBs on surface layer chlorophyll-concentrations indicates that the concentrations in the winter periods were generally higher than those in the summer periods. Summer concentrations in 2017 revealed comparable values with the previous summer periods.
2014-2017 surface layer chlorophyll-a concentrations at the Marmara Sea CWBs are shown in Graph 46. The highest concentrations are observed in Bandırma and İzmit Gulf and in İstanbul Strait. Spring concentrations those were measured in 2017 for the first time within the monitoring programme, turns out to be close to the summer concentration levels. The summer concentrations in 2017 reveal compatibility with the ones in previous periods
GRAPH 43- MEDITERRANEAN SEA CHLOROPHYLL-A AVERAGE CONCENTRATIONS - 2014-2017 COMPARISON
Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2111 (Mediterranean Final Report, 2017), February 2018, Gebze-Kocaeli.
GRAPH 44- AEGEAN SEA CHLOROPHYLL-A AVERAGE CONCENTRATIONS 2014-2017 COMPARISON
Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2113 (Aegean Sea Final Report, 2017), February 2018, Gebze-Kocaeli.
GRAPH 45- BLACK SEA CHLOROPHYLL-A AVERAGE CONCENTRATIONS 2014-2017 COMPARISON
Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2115 (Black Sea Final Report, 2017), February 2018, Gebze-Kocaeli.
GRAPH 46- MARMARA SEA CHOROPHYLL-A AVERAGE CONCENTRATIONS 2014-2017 COMPARISON
Source: ÇŞB-ÇEDİDGM and TÜBİTAK-MAM (2018). Integrated Pollution Monitoring Project (2017-2019). ÇTÜE 5178702, Report No. ÇTÜE.17.2116 (Marmara Sea Final Report, 2017), February 2018, Gebze-Kocaeli.