The abundance of microplastics (MP) in the ocean has increased dramatically in recent decades, particularly in the coastal areas with the largest population. Recent studies have proven the aggregation of MPs with trace elements and persistent organic pollutants. Further studies have aimed to clarify toxicity of MPs in sentinel organisms and the possibility of toxicity increase due to the association with chemical contaminants. The link between MPs and naturally occurring toxins during blooms of toxic algae has not been documented to date, to our knowledge. The relevance of this hypothesis results from the fact that currently dissolved toxins are quantified by adsorption to polymers that are placed in seawater.
This proposal has as general objective to identify the species of bivalves, captured and produced in Portugal, more sensitive to MP ingestion. Access to bivalve samples obtained under the National Bivalve Monitoring Program will allow to study influence of environmental, oceanographic and hydrological conditions on key species of estuaries and coastal lagoons (mussels, clams and oysters) and coastal areas (mussel and oyster ). The effect of floods on the quantity and types of MP ingested by bivalves will be assessed, which will contribute to the development of scenarios of climate change and adaptive measures.
The second general objective is to identify naturally occurring toxins during toxic algae blooms in Portugal that have a greater affinity for MPs. Experiments that will be carried out in the laboratory and in the field will allow to test different types, sizes, forms, age and chemical composition of MPs. Biochemical responses of selected species will be studied after exposure to MPs, and aggregates of MP-toxins and toxic phytoplankton. Finally, the proposal aims to clarify whether the intensity of bivalve toxicity or periods of ban on human consumption are affected by the ingestion of MP-marine toxin aggregates. The results will be obtained through field experiments during the occurrence of toxic algal blooms and laboratory experiments. According to the team’s knowledge, the MPs’ impact on the partition and availability of toxins during toxic algal blooms has not been examined so far.