Mucilage Problem in the Sea of Marmara
Changes in the Discrete Nutrient Salt Loads from the Bosphorus Current During the Marmara Sea Musilage Formation Period 2007-2008
Hüsne Altıok, Ahsen Yüksek, Tülay ÇokacarThe monthly and seasonal monitoring studies between 2007-2008 were evaluated to study the change in physicochemical dynamics of the sea under extreme winds and rain conditions. To achieve this purpose, monthly temperature, salinity, NOx, PO4, ECMWF Era5 wind with a resolution of 0.25°, 3-hour 0.1° MSWEP precipitation data were used in a total of 6 stations, two of which are at the Bosphorus exits. Since the dynamics of the sea are changing abruptly within the days, it is very important to monitor the sea dynamics close to the instance of the extreme situation. Although the monthly and seasonal monitoring studies did not take into consideration any extreme situation, this is the accessible data for the mucilage period and yet provides monthly and yearly variation for the period covering the mucilage event. The meteorological analysis shows that the percentage of occurrence of winds above 10m/s wind speed in 2007 is less than the 1996-2010 long time averages. Extreme southerly winds with a daily average of 10 m/s were observed in late January and early February in 2007. The northerly winds at storm level were observed for a few days at 9-10 m/s levels in March and between September and November 2007. In 2008, northerly winds reaching 12 m/s occurred in late January and mid-February. It was determined that sea surface temperatures in January, February, June, and August 2007 were higher than long-term averages and their margins of variations. While in 2007 sea surface temperatures show a warmer winter period, in 2008 on the contrary, the sea surface temperatures were colder than the long-term averages. At station B2, the effective mixing with high salinity values in the upper water layer was assessed between January and October 2007. The abrupt increase in PO4 concentrations in the upper layer is observed while no significant increase in NOx is observed within the storm period in October 2007. In February and August, it was observed that the NOx and PO4 concentrations at the sub-halocline layer in 2007 are the order of magnitude higher than in 2008. The N/P ratios for February and August 2007 are 13.19 and 9.17. Tugrul et al. (2013, 2015) mention that the N/P ratios at a sub-halocline range between 8 and 12 at the exit of the Bosphorus to the Marmara Sea (1986-2001 period). The 13.19 N/P ratio observed in February is above this range. The high NOx concentrations and N/P ratio seen between late January and mid-February are most likely the result of mixing that arose with extremely strong winds of around 10 m/s.