Two decades of monitoring in marine debris ingestion in loggerhead sea turtle, Caretta caretta, from the western Mediterranean * F. Dom  enech * , F.J. Aznar, J.A. Raga, J. Tom  as Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, Valencia, Spain article info Article history: Received 10 June 2018 Received in revised form 8 October 2018 Accepted 9 October 2018 Available online 15 October 2018 Keywords: Marine debris ingestion Caretta caretta Good environmental status Plastic Mediterranean sea abstract Anthropogenic marine debris is one of the major worldwide threats to marine ecosystems. The EU Marine Strategy Framework Directive (MSFD) has established a protocol for data collection on marine debris from the gut contents of the loggerhead sea turtle (Caretta caretta), and for determining assess- ment values of plastics for Good Environmental Status (GES). GES values are calculated as percent turtles having more than average plastic weight per turtle. In the present study, we quantify marine debris ingestion in 155 loggerhead sea turtles collected in the period 1995e2016 in waters of western Medi- terranean (North-east Spain). The study aims (1) to update and standardize debris ingestion data available from this area, (2) to analyse this issue over two decades using Zero-altered (hurdle) models and (3) to provide new data to compare the only GES value available (off Italian waters). The composition of marine debris (occurrence and amounts of different categories) was similar to that found in other studies for the western Mediterranean and their amounts seem not to be an important threat to turtle survival in the region. Model results suggest that, in the study area, (a) period of stranding or capture, (b) turtle size and (c) latitude are significant predictors of anthropogenic debris ingestion (occurrence and amount) in turtles. The GES value for late juvenile turtles (CCL>40 cm) has decreased in the last ten years in the study area, and this is very similar to that obtained in Italian waters. We also provide a GES value for early juvenile turtles (CCL40 cm) for the first time. Recommendations arising from this study include ensuring use of (1) the standardized protocol proposed by the MSFD for assessing marine debris ingestion by loggerhead sea turtles and (2) the ecology of the turtles (neritic vs oceanic), rather than their size, to obtain GES values. © 2018 Elsevier Ltd. All rights reserved. 1. Introduction Any waste of natural or human origin found in marine or coastal environments is considered marine debris (Laist, 1997; MSFD et al., 2011). Anthropogenic marine debris is recognized as one of the greatest threats to marine ecosystems that compromise biodiver- sity and marine resources (Moore, 2008; Galgani et al., 2010; Sutherland et al., 2010; UNEP, 2011; CBD, 2012). Several million tons of anthropogenic debris reach the oceans annually, leaving critical amounts of items floating at the surface, deposited on the sea bottom at all depths, and stranded on coasts throughout the world (e.g., Ryan, 2013; Schlining et al., 2013; Suaria and Aliani, 2014). Ingestion of anthropogenic marine debris by marine vertebrates is an increasingly recognized phenomenon (Laist, 1997; Derraik, 2002; Gall and Thompson, 2015; Kühn et al., 2015). Marine tur- tles, in particular, appear to consume anthropogenic debris because they confuse it with food (Campani et al., 2013; Schuyler et al., 2015) and, not surprisingly, all species have been reported to have debris in their stomach contents (Gall and Thompson, 2015; Schuyler et al., 2015). Marine debris ingestion can cause sub-lethal or even lethal effects in these animals. Sub-lethal effects include dietary dilution or assimilation of contaminants derived from ma- rine litter (Bjorndal, 1997; McCauley and Bjorndal, 1999). In severe cases, debris can block or tear their digestive tracts resulting in the death of the turtles (Bjorndal et al., 1994; Tom as et al., 2002; Lazar and Gra can, 2011; V elez-Rubio et al., 2018). The Mediterranean Sea represents a semi-closed basin with high demographic density throughout its entire coastline and is one of the most polluted seas of the planet (Suaria and Aliani, 2014; Pham * This paper has been recommended for acceptance by Maria Cristina Fossi. * Corresponding author. Marine Zoology Unit, Cavanilles Institute of Biodiversity and Evolutionary Biology, University of Valencia, 46980, Paterna, Valencia, Spain. E-mail address: francesc.domenech@uv.es (F. Dom enech). Contents lists available at ScienceDirect Environmental Pollution journal homepage: www.elsevier.com/locate/envpol https://doi.org/10.1016/j.envpol.2018.10.047 0269-7491/© 2018 Elsevier Ltd. All rights reserved. Environmental Pollution 244 (2019) 367e378