Identifying macrofloating debris hotspots in the Mediterranean Sea applying multiplatform methodologies

Area of Science:

• Marine pollution
• Oceanography
• Environmental science

Background:

• The Mediterranean Sea is a major hotspot for marine litter, posing significant environmental challenges.
• Quantifying marine debris is difficult due to diverse survey methodologies.

Purpose of the Study:

• To assess the spatial abundance and distribution of macrofloating debris (> 2.5 cm) in the Mediterranean basin.
• To compare the effectiveness of different survey methods (research vessel, sailing vessel, aerial) and approaches (science, citizen science).

Main Methods:

• Visual surveys were conducted using research vessels, sailing vessels, and aerial methods.
• Both scientific and citizen science approaches were employed to gather data.
• Macrofloating debris was quantified in items per square kilometer.

Main Results:

• Aerial and research vessel surveys indicated litter densities of 1.88 ± 2.3 and 0.89 ± 1.61 items·km⁻² respectively for the entire Mediterranean.
• Hotspots for macrofloating debris were identified in the eastern Algerian, Tyrrhenian, Adriatic, and Alboran Seas.
• Aerial surveys detected higher debris amounts than research vessels, highlighting differences in detection capabilities. Sailing vessels recorded high densities in Spanish waters, including a Marine Protected Area.

Conclusions:

• No significant differences were found between citizen science and scientific methods, suggesting citizen science is a valuable tool for data collection.
• The abundance of macrofloating debris is influenced by factors such as riverine input, population density, and oceanographic currents.
• Understanding debris distribution is crucial for effective marine pollution management in the Mediterranean.