From source to sink: A comparative study of streamside and beach litter in the Black Sea.

The increasing amount of marine litter pollution and its impact on the marine environment raises global concern. This study aims to reveal the effect of streams on marine litter density and composition. A total of ten stations on the southeastern Black Sea and six stations on the Manahoz stream were seasonally surveyed. The litter density ranged between 0.838 ± 0.33 and 4.01 ± 0.55 items/m2 in the beach stations, and 0.93 ± 0.27 2.40 ± 2.18 items/m2 in the streamside stations. No significant difference was determined among the seasons for both beach and streamside (Kruskal-Wallis test, p > 0.05). On the other hand, the litter density was also similar in beach and streamside stations in the same season. The litter composition consisted of > 75% plastic. Principal component analysis and PERMANOVA determined no significant difference in litter composition among beach and streamside stations. The litter items mostly consisted of single-use items. Among them, plastic beverage containers were the most abundant litter subcategory during the study (ranging between 18.79% and 34.50%). The subcategory composition exhibited a significant difference among beach and streamside stations (ANOSIM, p < 0.05), which was mainly explained by plastic pieces, beverage containers, and foams according to SIMPER analysis. Personal protection equipment that was not reported before the COVID-19 pandemic emerged. The results of our study can be used for marine litter modeling studies and legislation for restriction or ban of most abundant single-use litter items.

Spatial pattern and characteristics of the benthic marine litter in the southern Black Sea shelf.

The abundance and characteristics of benthic marine litter in the southern Black Sea shelf were demonstrated. During the surveys, 671 litter items weighing 83.93 kg were collected from the stations. The average density by number and weight were 460.70 ± 99.71 n/km2 and 80.68 ± 48.06 kg/km2. The litter density was significantly higher at 10-20 m (646.09 ± 165.63 n/km2) compared to 20-30 m (165.53 ± 81.02 n/km2) and >30 m (413.87 ± 146.59 n/km2) depth classes. Plastic (69.03%) was the most abundant material by number, followed by textile (20.94%) and metal (5.68%). The litter composition differed between the no-trawl zone and trawl ground. Our results indicate that more detailed research is needed to understand the interaction of various factors influencing transportation and accumulation of marine litter in the Black Sea.