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TURTLE fibropapillomatosis

Most sea turtle populations are currently in danger of extinction (http://www.iucnredlist.org/) due to numerous factors such as ingestion of debris, degradation of feeding and breeding areas, collision with boats, entanglement in fishing nets, pollution, predation by wild or domestic animals and climate change (Bjorndal, 1995; Herbst and Klein, 1995a; Lutz, 2002; Van Houtan et al., 2010). Many conservation measures seek to mitigate the effect of some of these factors with varying degrees of success (Chaloupka et al., 2008a). However, the emergence of fibropapillomatosis and associated mortalities makes the conservation of these species more than uncertain. Fibropapillomatosis (FP) is a neoplastic circumtropical disease increasingly present in the populations of several species of marine turtles (the loggerhead turtle (Caretta caretta) (Harshbarger, 1991), the Kemp’s turtle (Lepidochelys kempii) (Barragan and Sarti, 1994), the hawksbill turtle (Eretmochelys imbricata) (D’Amato and Moraes-Neto, 2000), the olive ridley turtle (Lepidochelys olivacea) (Aguirre et al., 1999), the flatback turtle (Natator depressus) (Limpus et al., 1993) and the leatherback turtle (Dermochelys coriacea) (Huerta et al., 2002)), but particularly in green turtles (Chelonia mydas, Williams et al., 1994). This pathology was first observed in Florida in the 1930s (Smith & Coates, 1938) and has been considered an epizootic (epidemic affecting animals) since the 1980s (Aguirre & Lutz, 2004; Farrell et al., 2018; Williams et al., 1994) with prevalence rates which can now reach more than 60% in certain regions (Jones et al., 2016). Surprisingly, these prevalence can show strong variations on a fine spatial scale. 

Fibropapillomatosis is characterized by the appearance of tumor masses from 0.1 to more than 30 cm in diameter which develop mainly in the epidermis of soft tissues, such as the eyes, neck, cloaca or joints of the forelegs or posterior. Visceral nodules can also develop on internal organs, such as in the lungs, heart or kidneys (Balazs & Pooley, 1991; Herbst, 1994; Morrison et al., 2018; Work et al., 2004). FP appears to influence mortality rates in sea turtles because the tumors that develop can pose infection risks, can increase the chances of entrapment in fishing nets, impair locomotion, vision and feeding and even affect the normal functioning of internal organs (dos Santos et al., 2010; Herbst, 1994; Herbst & Klein, 1995; Jones et al., 2016; Work et al., 2004). 

The “chelonid alphaherpesvirus 5” virus (ChHV5) appears to be the main etiological agent of this pathology, since its presence is strongly linked to the development of tumors (dos Santos et al., 2010; Hargrove et al., 2016; Jones et al. , 2016; Lackovich et al., 1999; Lu et al., 2000; Morrison et al., 2018; Page-Karjian et al., 2012; Patrício et al., 2012). However, the transmission of this virus between individuals, the physiological and genetic variables influencing the development of tumors in individuals carrying the virus and the importance of environmental factors in the development of this pathology are currently very poorly understood (Jones et al., 2016). In addition, recent molecular studies show that individuals who do not develop tumors can be carriers of the ChHV5 virus, suggesting that early stages of infection and/or periods of latencies of the virus could be more widespread than initially assumed in natural the environment (Page-Karjian et al., 2012; Alfaro-Núñez et al., 2014). 

Our project is to monitor individuals across several sites and for several years, to monitor the prevalence and growth dynamics of tumors in relation to environmental conditions and the health of the green turtle individuals of Martinique. Measurements of exposure to pollutants (heavy metals and persistent organic pollutants), virology (different variants of ChHV5) and physiological markers of health are carried out in order to better understand their importance in the dynamic and progression of this disease.