Fiber entanglements as a proxy for anthropogenic pollution uptake : Monitoring deep-water rose shrimp (Parapenaeus longirostris) throughout the year

Anthropogenic pollution is considered one of the most concerning threats to marine wildlife and several studies have highlighted that decapod crustaceans might be amongst the most impacted organisms. However, limited attention has been given to the deep-water rose shrimp (Parapenaeus longirostris), a Mediterranean crustacean with great ecological and commercial value, especially in the westernmost areas of its distribution. This study analyses variations in anthropogenic fibers (AFs) ingestion in P. longirostris throughout the year, as well as potential effects on their health status in the northwestern Mediterranean Sea. Individuals were collected during eight months over the course of a year at depths of 200-500m off the coast of Barcelona. Digestive contents were visually examined to detect the presence of isolated and entangled fibers, which were further characterized using optical microscopy and FTIR spectroscopy. Over 80 % of individuals had ingested AFs with an average abundance of 3.08 fibers per individual. Tangled fibers were also common (∼50 %) and reached mean values around 2 mm in diameter. Differences throughout the year were observed in the polymer composition of fibers and the prevalence of entanglements. Additionally, the relationship between the prevalence and complexity of entanglement and biological traits (reproduction and molting) was discussed. No clear effects of the overall occurrence of AFs on shrimp condition were observed. Nonetheless, the findings point out that these decapods are among the marine faunal groups with the highest AF uptake. Fiber entanglements provide a longer temporal integration window for monitoring plastic pollution compared to other commonly used groups (e.g., fish). Thus, using fiber entanglements as a proxy for anthropogenic pollution, combined with the selection of P. longirostris as a target species, presents a trustworthy and affordable approach for assessing environmental plastic contamination.