OUR BLACK SEA: HOW ITS CONDITION HAS CHANGED OVER THE LAST 20-30 YEARS

According to the marine monitoring carried out by the Ukrainian Research Center for Marine Ecology jointly with the EU/UNDP project “Improving Environmental Monitoring in the Black Sea” (EMBLAS), the following trends have been identified:

–Eutrophication (ie supersaturation of nutrients), which causes, for example, seasonal “blooming” of blue-green algae ↓ : according to the TRIX index, which shows the level of eutrophication of surface waters of the shelf, and the BIST index, which shows the level of impact of eutrophication on the entire shelf waters, there has been a positive trend to reduce its levels during the last 20 years.

–Marine litter and plastic pollution ↑ : scientists have started to measure this parameter only recently. Currently, the amount of waste in the Black Sea is 90.5 units per 1 km2, which is twice as much as the figure for the Mediterranean Sea.  The amount of garbage in the Black Sea is growing, because, according to monitoring data, large rivers bring  from  6 to 50 items of garbage into the sea every hour.

–The depth of the hydrogen sulfide layer ↑ : as you know, 90% of the Black Sea is an oxygen-free zone filled with hydrogen sulfide. Over the past 30 years, the hydrogen sulfide layer has risen by 20 m. Imagine, now the depth of the oxygen-saturated layer in the center of the Black Sea is 54 m only.

–Number of dolphins = According to the latest “census” of cetaceans, conducted in 2019, their total number is 253 thousand. The results of the survey show us that the state of Black Sea cetacean populations has not deteriorated over the past 20 years.

–Chemical pollution ↑ ?: in total, 124 Black Sea specific pollutants have been identified. These include persistent organic pollutants, metals, pesticides, biocides, pharmaceuticals, flame retardants, industrial pollutants, and personal health care products. Monitoring of the chemical status of the Black Sea has been ongoing since 2016 with the support of the EMBLAS project. The following results of the assessment of the chemical status of bottom sediments (which actually keep the “memory” of marine pollution) are obtained for the marine water bodies:

1)Danube Delta ↓ (from “satisfactory” as a basic assessment to “poor” in 2021). The same trend is observed for the Danube water body.

2)Dniester Bay =: chemical status class remains “satisfactory”.

3)Dnipro-Bug estuary ↓: (from “good” as a basic assessment to “satisfactory” in 2019).

4)Kinburn Spit ↑: (from “bad” as a basic assessment to “very good” in 2019).

5)From the Dniester Bay to the Odesa Bay and from it to the Tendriv Bay ↑ : the class of the chemical status has improved: from “satisfactory” to “good”, and correspondingly from “bad” to “satisfactory”.

6)The zone of mixing of the waters of the Black Sea north-western shelf with the waters of its central open deep-water part = chemical condition remains “satisfactory”.

-The pressure of invasive species ↑ – not “native” to the Black Sea species that can harm the marine ecosystem is growing. Using a new method of analysis of DNA residues of living organisms dissolved in seawater, new Mediterranean species were found in the Black Sea, namely Monroe surgeon fish, red barracuda, burrowing bull, etc.

All this data will be the basis for the development of the Program of measures to improve the Black Sea status.