Monitoring marine litter impacts on sea turtles. Protocol for the collection of data on ingestion and entanglement in the loggerhead turtle (Caretta caretta Linnaeus, 1758). Version 1.

Abstract

The following protocol is intended to respond to the MSFD requirements for the indicator 10.2.1 “Trends in the amount and composition of litter ingested by marine animals”. The INDICIT program proposed marine turtles as an indicator species to study marine litter ingestion on biota through the development and the implementation of one major indicator “Litter ingested by sea turtles”. Standardized methodologies for extracting litter ingested from dead and live individuals are exposed in this document. Some modifications have been conducted from the original methodology drafted and tested in Italy since 2012 (Matiddi et al., 2011; MSFD TG Litter, 2013), following the first applications (Camedda et al., 2014; Matiddi et al., 2017) and within the European Project INDICIT (GA n°11.0661/2016/748064/SUB/ENV.C2) as well as thanks to the feedbacks of rescue centres and stranding networks. Both “basic” and “optional” parameters are proposed to be collected. The basic parameters (thereafter noted in bold) correspond to the minimum parameters fundamental to determine the indicator criteria. The optional parameters (thereafter noted in bold italic grey) allow acquiring more knowledge on loggerheads’ behaviour and probability to ingest debris and better specify the indicator criteria in development. The optional parameters can also help to better assess the relevance of two new indicators on litter impacts for which pilot studies are in process (“Entanglement with marine debris by biota” and “Micro-plastic debris ingested by sea turtle and fish”). Following the MSFD Technical sub-group on Marine litter (Galgani et al., 2013) and the new Commission Decision (Decision 2017/848 of the 17th March 2017), the minimum size of litter items considered for the indicator “Litter ingested by sea turtles” is 1 mm, thus including both micro (1-5 mm) and macro-plastics (> 5 mm). An observation sheet is provided in Appendix. In order to facilitate banking and statistical analysis, data must be filled in the INDICIT corresponding standardized table, by respecting the units and proposed menu choices, and specifying remarks or other proposals in the last column “Note”. All boxes must be filled, either by the information (data) or by 0 or “NA” (information not available or not evaluated).