EGU25-11639, updated on 15 Mar 2025
https://doi.org/10.5194/egusphere-egu25-11639
EGU General Assembly 2025
© Author(s) 2025. This work is distributed under
the Creative Commons Attribution 4.0 License.
Marine litter pollution in the Western Mediterranean: new insights from the OBAMARAN project
Javier Soto-Navarro1, Jorge Ramos-Alcántara1, and Gabriel Jordà2
Javier Soto-Navarro et al.
  • 1Physical Oceanography Group of the University of Málaga (GOFIMA). Málaga, Spain
  • 2Centre Oceanogràfic de les Balears, Spanish Institute of Oceanography (COB-IEO/CSIC). Mallorca, Spain

Marine litter (ML) pollution has become a major concern in the Mediterranean, a semienclosed basin that receives large amounts of pollution from its highly populated coasts. However, there are concerns about how reliable is the picture we have at present about this problem. In particular, the amount of existing ML and the ML sources are key aspects that have not been yet completely clarified. In the context of the OBAMARAM project, which aims to characterize the origin and evolution of marine debris along the southern Spanish coastline, a series of studies have been conducted that offer novel insights into those key aspects. Initially, a series of observing system simulation experiments (OSSE) were conducted to assess the capabilities of different monitoring strategies to estimate the average concentration of marine litter in the Western Mediterranean within an acceptable range of uncertainty. The results demonstrate that conventional sampling strategies are inadequate for reliable estimation of temporal averages and spatial means at the basin or sub-basin scale. However, these strategies can be representative of spatial averages at the synoptic scale in smaller regions.

Subsequently, a comprehensive survey of available marine litter observations in all compartments of the western Mediterranean marine environment was made. For this purpose, 180 scientific publications were analyzed. Moreover, several open access databases were consulted to collect data on the abundance of plastics on the sea surface in the region, gathering information from more than 800 net trawls conducted during the period between 2011 and 2022. The results were then used to produce concentration maps based on observations and a homogenized surface sampling database. The study's primary finding is that the available observations are inadequate in characterizing the concentration of marine debris in the basin, given its dispersion both spatially and temporally. Additionally, there is a lack of coordination and standardization in the measurement techniques, which complicates data homogenization and intercomparison.

After this, the problem of the identification of ML sources has been addressed for the Balearic Islands, where a homogeneous and continuous database is available in time. Here, observations from cleaning campaigns were combined with numerical simulations to generate an inverse model that allows estimating the origin of marine litter collected in different regions of the coast of the archipelago. This approach has allowed to identify the main areas of ML disposal, although the uncertainties are significant and has some limitations that will be discussed in the presentation.

Finally, a very high resolution numerical study has been designed to parameterize the ML import and export between the nearshore and the open sea. The main goal is to identify under what conditions there is an effective transfer of ML from the coast to the open sea. This will help in the identification of ML sources.

How to cite: Soto-Navarro, J., Ramos-Alcántara, J., and Jordà, G.: Marine litter pollution in the Western Mediterranean: new insights from the OBAMARAN project, EGU General Assembly 2025, Vienna, Austria, 27 Apr–2 May 2025, EGU25-11639, https://doi.org/10.5194/egusphere-egu25-11639, 2025.