Monitoring Litter Inputs from the Adour River (Southwest France) to the Marine Environment

Antoine Bruge,Clément Moreno,Hélène Collin,Jérémy Carlot,Cristina Barreau,Philippe Maison

doi:10.3390/jmse6010024

Abstract

Rivers are major pathways for litter to enter the ocean, especially plastic debris. Yet, further research is needed to improve knowledge on rivers contribution, increase data availability, refine litter origins, and develop relevant solutions to limit riverine litter inputs. This study presents the results of three years of aquatic litter monitoring on the Adour river catchment (southwest of France). Litter monitoring consisted of collecting all litter stranded on river banks or stuck in the riparian vegetation in defined areas identified from cartographic and hydromorphological analyses, and with the support of local stakeholders. Litter samples were then sorted and counted according to a list of items containing 130 categories. Since 2014, 278 litter samplings were carried out, and 120,632 litter items were collected, sorted, and counted. 41% of litter could not be identified due to high degradation. Food and beverage packaging, smoking-related items, sewage related debris, fishery and mariculture gear, and common household items represented around 70% of identifiable items. Overall, the present study contributes to our knowledge of litter sources and pathways, with the target of reducing the amounts entering the ocean. The long-term application of this monitoring is a way forward to measure societal changes as well as assess effectiveness of measures.

Highlights

Oceans are priceless resources to humanity, especially for oxygen production and food
We considered that several item categories were missing in the OSPAR list and decided to complete it with items frequently found on river banks
While the method used does not allow the quantification of litter inputs to the ocean, it shows similarities between litter present in rivers and marine litter

Summary

Introduction

Oceans are priceless resources to humanity, especially for oxygen production and food. Many coastal communities rely on traditional fishing activities for survival and are highly dependent on ocean health [1]. The combined impact of climate change [2], overfishing, and pollution leads to marine ecosystem changes [3] and biodiversity loss. Marine debris pollution is known to affect marine wildlife and represents additional pressure on already threatened species. Every compartment of the ocean is of concern: sea surface, seabed, water column, and shorelines [4]. 693 species were reported to have encountered marine debris, of whom 92% were plastic debris [5]. The impact of plastic debris on marine life includes entanglement, ingestion, contamination of the food chain by persistent pollutants, and introduction of exotics species [6]

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