Marine litter in the Red Sea: Status and policy implications.

The Red Sea's unique ecosystem is home to >1500 species. However, the presence of anthropogenic litter, whether from land-based or sea-based sources, may pose a potential risk to the Red Sea fauna and flora. This work analyzes marine litter in the Red Sea, utilizing the Drivers-Pressure-State-Impact-Response (DPSIR) framework to group findings in a survey of peer-reviewed studies. The review is further augmented with a survey of the current response, covering regional and national instruments. Although research addressing marine litter in the Red Sea is not as rich as for other seas, studies suggest marine litter is abundant and that the influx of litter is driven by recreational activity, fishing, and shipping. Moreover, the COVID-19 pandemic has exacerbated the influx of marine litter to the Red Sea due to improper disposal of personal protective equipment (PPE). The response has intensified in recent years, with regional and national frameworks established and initiatives driven by Non-Governmental Organizations (NGOs). We discuss whether the regional action plan addresses the specific concerns uncovered in marine litter studies while providing a comparison with plans of other regional seas.

Does microplastic ingestion by zooplankton affect predator-prey interactions? An experimental study on larviphagy.

Litter is omnipresent in the ocean where it can be ingested by marine biota. Although ingestion of microplastics (MPs) is abundantly reported, insights into how MP can influence predator-prey interactions currently limits our understanding of the ecological impact of MPs. Here we demonstrate trophic transfer of MPs from zooplankton to benthic filter feeders, through consumption of contaminated prey (i.e. prey with ingested MP). However, predation rates of contaminated prey were significantly lower as compared to predation rates of prey that had no MPs ingested. As filter feeder clearance rates were not affected by consumption of MPs, the lower predation rates of contaminated prey appear to be primarily explained by disruption in zooplankton swimming behaviour that reduces their filtration risk. This is the first study that shows how MPs can change predator-prey interactions that are involved in the coupling between the pelagic and seabed habitat.

Leave no traces - Beached marine litter shelters both invasive and native species.

Marine litter has been considered a potential transport vector of non-indigenous species. In this study developed in Tjärnö (Sweden), at the entry of the Baltic Sea, the communities inhabiting coastal litter and natural substrates (N = 5448 macroorganisms) were monitored from eight sites of different ecological conditions. The results showed that litter can support high densities of marine organisms and represent a new habitat in the studied coast. The taxonomic profile of the communities supported by marine litter and hard natural substrate were significantly different. Moreover, opposite to the expectations of reduced diversity in artificial structures, more diverse communities were found on litter. Non-indigenous species were attached mainly to non-plastic artificial materials. From these results it can be concluded that marine litter can significantly alter the biotic composition of coastal ecosystem, representing a shelter for invasive species and diverse natives.