Relationship between fibropapillomatosis and environmental quality: a case study with Chelonia mydas off Brazil

Abstract

We documented the presence of fibropapillomatosis (FP), a debilitating tumor-forming disease, in marine turtles in Espírito Santo Bay (Brazil) from March 2007 to April 2008, and assessed the value of a specific environmental index for predicting the prevalence of FP. Turtles were captured monthly with entanglement nets and scored for presence and severity of FP. For the assessment of habitat quality, we used the ecological evaluation index (EEI) based on benthic macrophytes. The FPfree control area was classified as good quality (EEI = 8) and the study area, with high FP prevalence, was classified as bad quality (EEI = 2). Prevalence of FP in the study area was 58.3% with an average of 40 tumors per individual, and prevalence varied positively with curved carapace length (CCL). No FP was seen in the control area. The number of turtles heavily afflicted (tumor score category 3) was 10 times larger than those lightly affected (tumor score category 1). Most tumors were found on or near the front and rear flippers; no oral tumors or internal tumors were found. At recapture, 41% of formerly tumor-free turtles revealed FP, often increasing in severity with time, and very few turtles showed signs of disease regression. From the results of this study we concluded that FP is particularly severe in Espírito Santo Bay. Future studies should focus on evaluating how widespread FP is in Brazil, whether prevalence is increasing or decreasing, and elucidating the pathology and pathogenesis of FP in sea turtles in Brazil. KEY WORDS: Fibropapillomatosis · Environmental quality · Chelonia mydas · Green turtle · Ecological index · BrazilResale or republication not permitted without written consent of the publisher Dis Aquat Org 89: [87][88][89][90][91][92][93][94][95] 2010 Conservation of Nature and Natural Resources (IUCN) (Seminoff 2004). In addition to anthropogenic threats, diseases such as fibropapillomatosis (FP) may pose additional threats to Chelonia mydas (Herbst 1994, Aguirre et al. 1998.FP is a debilitating disease affecting marine turtles that can impair foraging and internal organ function; it is characterized by the development of tumors on the eyes, oral cavity, skin, carapace, plastron or internal organs (Balazs 1991, Jacobson et al. 1991, Herbst 1994, Aguirre et al. 2002, Work et al. 2004, Foley et al. 2005. The disease mainly affects green turtles (Herbst 1994, Aguirre et al. 1998, 2002, but it has also been documented in other species (George 1997). FP is associated with a herpesvirus (Herbst 1994, Quackenbush et al. 1998, but the role of this agent in causing disease has not been clarified, and it appears other, as yet unidentified, factors probably play a role. It is known that turtles afflicted with FP have higher parasite loads (Work et al. 2005), are immunosuppressed (Work et al. 2001) and bacteraemic (Work et al. 2003).Considerable geographical variation in the prevalence of FP exists (0 to 92%), and substantial differences may be found even between relatively close areas (Ehrhart 1991, Herbst...

The green turtle Chelonia mydas as a marine and coastal environmental sentinels: anthropogenic activities and diseases

“…The frequency of juveniles stranded with ingested debris in Uruguay (South America) has been estimated at 73%, but reached 90% in Rio de la Plata -for both margins (Uruguay and Argentina/ GONZÁLEZ-CARMAN et al, 2014;TERYDA, 2015). Similarly, high frequencies of debris ingestion were observed along the Brazilian coast, and varied from ~60% to 100% in Rio Grande do Sul, southern Brazil (BUGONI et al, 2001;TOURINHO et al, 2010), 70% in Paraná state, southern Brazil (GUEBERT- BARTHOLO et al, 2011;GAMA et al, 2016), from 45% to 70% in São Paulo state, southeastern Brazil (BEZERRA, 2014;MENDES et al, 2015), ~60% from Rio de Janeiro to Espírito Santo state, southeastern Brazil (DiBENEDITTO; AWABDI, 2014;SANTOS et al, 2015) and 70% in Sergipe state, northeastern Brazil (SANTOS et al, 2015). It is interesting to note that the large frequencies of debris ingestion observed in Uruguay, Argentina and Brazil are a warning for the conservation of C. mydas, because these areas are considered to be part of an important migratory corridor in the southwestern Atlantic Ocean.…”

“…Fibropapillomatosis is associated with the life cycle of C. mydas, because tumors are observed in postrecruitment juveniles and adults in neritic areas but is absent in oceanic areas (ENE et al, 2005;JONES et al, 2016). Some environmental factors, such as high levels of contamination, water temperature and concentration of viral strains in neritic areas have been associated with FP (HERBST, 1994;SANTOS et al, 2010;RODENBUSCH et al, 2014).…”

“…In some areas cited above, death rates can vary from 0 to 29%. Only 0.5 g of debris is enough to obstruct the intestine and lead to starvation and ultimately, death (BUGONI et al, 2001;TOURINHO et al, 2010;SANTOS et al, 2015). Other negative impacts of marine pollution are obstacles that create difficulties for (i) females to select an ideal site to nest and (ii) hatchlings to travel from the nest towards the sea, with consequently a greater vulnerability to predation and grounding at nesting beaches, and (iii) eggs permeability and/or temperature alteration, which can influence dehydration and sex ratio, since sea turtles are sex temperature-dependent (NELMS et al, 2016).…”

“…gradual shift from an omnivorous to herbivorous diet) and (iii) different impacts caused by human activities and contact with pathogens (FLINT, 2013;SANTOS et al, 2015). Therefore, C. mydas is considered an environmental sentinel that can indicate hazards and which ultimately can be used to support priority actions to address intervention to maintain or improve the environmental quality and animal's health across regional and global scales (AGUIRRE; LUTZ, 2004;REIF, 2011).…”

Health condition of juvenile Chelonia mydas related to fibropapillomatosis in southeast Brazil

“…In Brazil, fibropapillomatosis (FP) is considered the most important disease threatening sea turtles (Matushima et al 2001, Baptistotte 2007, Santos et al 2010. It is a cosmopolitan transmissible neoplasia, probably of herpesviral etiology, that results in external and internal tumors which affect the function and survival of the turtles (Herbst 1994, Matushima et al 2001, Aguirre & Lutz 2004, Rodenbusch et al 2012.…”