MUCILAGE FORMATION and ITS EFFECTS on the SEA of MARMARA (part-3)
2.3. Mucilage on Sea of Marmara
The Sea of Marmara is a sea of Turkey with small size basin ~70km x 250 km (surface area: ~11,500 km2, maximum depth 1390 m). This basin is located between the continents of Europe and Asia. Black Sea water with less saline which is present surface layer of The Sea of Marmara between 0 and 25 m depth, whereas the high salinity Mediterranean water that presents downward 25 m deeper layers.
The Sea of Marmara is between the Black Sea and the Aegean Sea, with saline (up to 40‰) lower layer from the Mediterranean Sea overlain by brackish waters (~20‰) from the Black Sea. The system is permanently laminal , with the İstanbul and Çanakkale Straits and the seaside embayment, and shifts from mesotrophic to eutrophic situation depending on location and season [20]. The Marmara ecosystem, which comprises biological components from both seas, is matchless [21]. In Turkey, the Marmara region ranks top in terms of population density and economic activity. The region in the first place in terms of population density and economic activity in Turkey is the Marmara region. As a result, urban wastewater, waste load and pollution are increasing due to rapid population growth [22].
Figure 4: Satellite images of mucilage in the Sea of Marmara
Figure 5: Mucilage image formed in Istanbul/Tuzla Coastal Region
The mucilage phenomenon in the Marmara Sea (Figure 4-5-6.) has started to be seen since the first months of 2021. The rate of increase in mucilage in the Sea of Marmara has started to be clearly seen in the satellite images taken from space by ITU CSCRS, Turkey's first earth satellite station, as of March. It was stated that mucilage reached an area of 25 square kilometers on May 14, 58 square kilometers on May 19, and 85 square kilometers on May 24 in the eastern part of the Sea of Marmara from the Kapıdağ Peninsula to the Gulf of Izmit (ITU,2021).
Figure.6: Seabed images of mucilage in the Sea of Marmara
A causal loop diagram representing the main system components for the dynamic mechanism for the mucilage problem in the Sea of Marmara is given in Figure 7. As summarized in Figure 7., mucilage formation is an event triggered by an increase in light and temperature. If the nitrogen and phosphorus needed as a nutrient source are present in the environment, phytoplanktons will rapidly multiply and release mucilage. Additionally , some minor elements such as iron can contribute to the formation of mucilage by playing a catalyst role in the nitrogen cycle. Overfishing reduces the number of fish that feed on phytoplankton, thus increasing mucilage production. As shown in Figure 7., the amount of dissolved oxygen will be very high in the first stage when phytoplanktons multiply rapidly. After all, because of bacterial decay, there will be a rapid decrease in oxygen in the following phases. This condition will have a negative impact on benthic species, as well as the economy, as fisherman will not be able to hunt. Visual pollution will also have an adverse effect on the tourism industry. Low dissolved oxygen levels, aquatic creature death, and food chain disturbance are all ecological implications of mucilage [23]. In the end, the mucilage problem has critical negative effects for the ecology, human health, and the economy.
Figure 7: Causal loop diagram representing the dynamic mechanism for the mucilage problem in the Sea of Marmara
2.4. Mucilage effects to marine environment
Marine mucilage does have a variety of harmful effects. There have been many studies on the formation of marine mucilage and it creates social and economic concerns and problems in many areas such as coastal areas, maritime transport and fisheries.The effects of mucilage are listed as follows:
1. Extinction of aquatic life
2. Fishery
3. Tourism
4. Maritime transportation and vessels
5. Release of harmful gases into the atmosphere
The correct strategy is to eliminate the elements that cause mucilage formation before it occurs; otherwise, the only option is to collect mucilage from the water using different marine boats and technologies. Observation of mucilage in the Turkish Straits and potential causes determined the marine pollutants that can cause mucilage as follows:
· Pollution from household waste that occurs due to the direct or indirect mixing of wastes such as sink wastes into the sea, with or without treatment in sewage systems.
· Pollution from industrial wastes that arises when industrial wastes (cooling water and chemical wastes including heavy metals and chemicals) from 143 densely located industrial facilities along the Marmara Sea reach the sea after being directly/partially treated/purified.
· Agricultural waste caused by chemical fertilizers and pesticides used in agricultural activities reaching the sea in various ways.
· Pollution from ships and marine vehicles.
· Waste and pollution transported from other seas by surface and
· undercurrents transferring pollutants and microplastics to the Sea of
· Marmara due to the interconnection of seas and rivers.
· Other waste due to air pollution, which is not mentioned in the above articles, direct pollution of the seas by waste, dust, pollen, etc.
Maritime operations on ships are very hazardous and need tremendous caution. The implications of any faults in these operations, which should be carried out with precisely by the whole ship crew, might be catastrophic. There are also uncontrolled external variables that impact marine operations, such as weather, environmental issues, warfare, etc. Mucilage is one of these external variables affecting ship operations, and it has recently caused considerable challenges for ships navigating through the Turkish Straits and the Sea of Marmara. When analysing the effects of mucilage on ship operations, whether directly or indirectly, it is obvious that the effect of mucilage on systems operating with seawater will be higher. These systems are listed below: Seachest Filters: In seachest filters, the mucilage settled in the filter pores can clog the filter in a short time and causes the flow of seawater to decrease. Figure 8. depicts the seachest filter of a ship sailing through the mucilage area.
Seachest Filters: In seachest filters, the mucilage settled in the filter pores can clog the filter in a short time and causes the flow of seawater to decrease.
Figure 8: Seachest Filters after mucilage
All systems that operate with seawater on ships sailing in mucilage area are likely to be adversely affected. In conclusion, the following impacts are very likely to be observed in ship operations;
· Even though mucilage is hard to remove from surfaces, it accumulates a layer on the filters and coolers.
· Mucilage causes heat to build up in ship machinery, decreasing machine efficiency.
· In heat exchangers, mucilage causes insufficient flow.
· Mucilage causes filter blockage.
· Corrosion is caused by mucilage.
· Mucilage clogs the hull and cooling pipes as it settles.
