Ingestion of chitosan-starch blends: Effect on the survival of supralittoral amphipods

Sandy beach ecosystems are particularly affected by plastic pollution. Supralittoral amphipods are important components of the food web in sandy beaches and their ability to ingest microplastics and bioplastics has been assessed. Chitosan, a polysaccharide obtained by deacetylation of chitin, the second most abundant polymer in the world, represents an interesting component to produce novel bioplastics in combination with other biopolymers like starch. Here, the possibility of ingesting chitosan-starch blends and the possible effects on the amphipod Talitrus saltator were investigated. Groups of adult individuals were fed with sheets containing mixtures of chitosan and starch in different percentages for 7 and 14 days. The results showed that chitosan ingestion is dependent on the percentage of starch present in the mixture. Moreover, FTIR analyses of both sheets and faecal pellets after consumption show that chitosan is not digested. Furthermore, the survival rate of amphipods fed with a mixture of chitosan and starch decreases after one week compared to the control groups (100 % starch and paper), and drops drastically to 0 % after two weeks the experiment began. In addition, consumption of 100 % chitosan is negligible. Therefore, the results of the experimental observations evidenced that chitosan is avoided as food resource and its consumption significantly affects the survival capacity of T. saltator. It is emphasized that the release of mixtures of chitosan and starch into the marine environment appears to be dangerous for littoral amphipods.