Although the problems linked to microplastics pollution are currently being tackled in different fields, an effort to find cost-effective management solutions for the environment is still necessary.
Many studies have revealed the potential ecological effects of plastic pollution: while damage from larger plastic items such as sachets primarily causes entanglement, for tiny particles, they occur by intentional or unintentional ingestion. The complex dynamics at the ecosystem level and the extent of plastic trophic transfer in marine environments are also among the greatest constraints.
Biomonitoring is therefore a crucial step in the assessment of the risks of marine environments linked to these particles. It provides biological responses that can guide political decision-makers and environmental managers in their environmental visions.
What is biomonitoring?
It is a method using a living organism (biochemical, cellular, physiological, etc.) to monitor the evolution, alterations, or stability of the quality of an environment.
This biomonitoring uses specific techniques including, mainly, the selection of species of bioindicators suitable for the ingestion of plastic. The ideal bioindicators for scientific studies are often benthic filtering organisms or large marine vertebrates, such as protected marine mammals, turtles and seabirds.
The bioindicator species must be selected according to key criteria: abundance, ecological relevance, tolerance to disturbances and stressors and a wide distribution comparable to a range of exposures.
The selection of bioindicator species must also take into account the difficulties linked to their behavior and their occurrence, which can strongly affect the sampling effort and the planning of monitoring activities. In addition, the abundance of plastic along the water column is influenced by various environmental factors such as tides, winds, currents and wave fronts which complicate the interpretation of biomonitoring data.
However, monitoring programs involving a wide range of synergistic bioindicators are still lacking. Jellyfish have recently been reported as target organisms for marine litter, capable of swallowing a number of macro / microplastics.
Being a widespread energy source in pelagic food webs and deep waters around the world and occurring at high densities, jellyfish can represent the bioindicator counterpart of invertebrates to monitor plastic pollution in pelagic waters, as well as their common predators.
Although still limited, fishing and consumption of these species worldwide has increased, especially in East Asia for jellyfish, which can contribute to the intake of microplastics and raises concerns for human health.
Given the exceptional attention paid to plastic pollution, it is crucial to select good bioindicators which will make it possible to determine the impacts of plastics as well as to understand the different routes along the marine food webs.