Marine litter is a pressing global issue that adversely affects our oceans. Advanced detection and quantification techniques are crucial for addressing the challenge of floating marine plastics. Remote sensing stands out as an invaluable tool for monitoring expansive marine areas due to its ability to cover large regions frequently and its potential for detailed observation.


As the scientific community pushes forward with refining sensors for marine litter monitoring, there is an urgent need for robust indicators to detect, classify, quantify, and track marine debris. Historical proof-of-concept studies have successfully used hyperspectral imaging for classifying marine plastics both in lab settings and within areas like the Great Pacific Garbage Patch.


Despite these advances, the field lacks a comprehensive reference dataset that captures the spectral behavior of plastics under real-world conditions or supports the calibration and validation of remote sensing algorithms. This gap led to the initiation of the Plastic Litter Projects (PLP).


The PLP aims to:

Assess the viability of using UAVs and the open-access Sentinel-2 mission to detect plastics in aquatic environments.
Obtain accurate spectral measurements in near-real scenarios.
Bridge the resolution gap between coarse satellite imagery and fine UAV data by simulating realistic satellite pixels.


Through these efforts, the PLP endeavors to enhance our understanding and management of marine plastics, fostering more effective conservation strategies for our oceans.


 Here’s how our project has evolved over the years:


PLP2018: Launched as a groundbreaking exploratory study, PLP2018 utilized open-access satellite imagery and unmanned aerial systems to remotely detect marine plastics. We introduced three large 10×10 m artificial targets that were precisely designed to match the Sentinel-2 RGB and NIR bands’ spatial resolution, setting a robust baseline for our methodologies.


PLP2019: Building on our initial insights, we developed ten smaller, more realistic targets to enhance our understanding of the limitations inherent in detecting marine litter using Sentinel-2 imagery. This phase brought us closer to replicating real-world conditions.


PLP2020: Our focus shifted towards establishing a scientifically validated reference target, robust enough for long-term environmental exposure. We innovated with semi-permanent targets to study their endurance in real marine conditions.


PLP2021: This year was dedicated to rigorously testing the durability of our reference target in a controlled environment. We introduced a specialized mooring system in the Gulf of Gera, Lesvos Island, Greece, securing our targets in situ for extended periods.


PLP2022: We concentrated on quantifying the smallest detectable traces of plastic within a 10×10 m Sentinel-2 pixel, experimenting with HDPE targets that mimic 1% and 3% plastic abundance. The year also saw us delve into the effects of biofouling and UV degradation on our synthetic materials, complemented by the introduction of innovative inflatable targets.


PLP2023: Embracing high-resolution satellite capabilities with the Super Dove constellation, we aimed at detecting minuscule concentrations of marine litter. We deployed varied target materials, from plastic to natural, beginning with white HDPE tarps, to discern different types of marine debris effectively.


PLP2024: Our current focus is on enhancing our detection algorithms and evaluating the efficacy of various satellite systems. By advancing our FML/FMD detection techniques and undertaking comparative studies between Planet SuperDove and Sentinel-2, we continue to refine our strategies. Our targets now simulate smaller windrows, commonly found in the Eastern Mediterranean and Aegean, adjusting from 1.2 to 4.8 meters in width and extending up to 100 meters in length.

Dr Konstantinos Topouzelis

Head of Marine Remote Sensing Group

Department of Marine Sciences, University of the Aegean