Ingestion of plastic debris affects feeding intensity in the rocky shore crab Pachygrapsus transversus Gibbes 1850 (Brachyura: Grapsidae)

Abstract

The aim of this study was to investigate the plastic consumption by the rocky shore crab Pachygrapsus transversus and its effects in the species feeding activity. Specimens were collected monthly from August 2019 to January 2020 in a coral reef located in the north-eastern Brazilian coast, taken to the research laboratory, where they had their stomach removed, degree of fullness determined for each stomach and presence/absence of plastic debris assessed. Frequencies of occurrence of each degree of fullness were compared between sexes and contaminated/non-contaminated individuals. At total, 209 specimens were sampled and high levels of plastic contamination were detected: 47.4% of the sample had plastic fibres in the foregut. All contamination consisted only of nylon filaments, suggesting that irregularly discarded fishing equipment is the source. The frequencies of contaminated individuals among sexes did not differ. However, differences were detected in the comparison between degrees of fullness, demonstrating that there is significant influence of plastic ingestion in the stomachs volume. It is possible that the discrepant frequencies of occurrence of gut fullness were due to false satiation effects and blockage of the digestive tract provided by the fibres.   Key words: Pollution, decapoda, ecology, brachyura.