The green sea turtle (
The green sea turtle is the most prevalent species on the Brazilian coast (Reis
In Brazil, there are still few studies detailing on the parasite fauna of juvenile stages of sea turtles. Only recently, Werneck and Silva (2015) in the state of São Paulo and south of Rio de Janeiro, and Binoti
From September to December 2020, 28 juvenile green sea turtles were found dead, stranded on the beach during monitoring activities (Werneck
Before necropsy, all sea turtles were weighed and the curved carapace length notch-to-tip (CCL) was measured to the nearest cm. Visual assessment of the body condition for each turtle was measured according to Thomson
At post mortem examination, the esophagus, stomach, small and large intestines were studied for helminth parasites following the methods described by Greiner
Prevalence, mean intensity of infection and mean abundance followed Bush
Species richness, mean abundance and mean intensity of infection were compared among turtle body condition classes and between turtles from different geographical areas using the non-parametric Mann-Whitney U test. The significance level adopted in the statistical tests was 5 %. Statistical analyzes were calculated using SigmaStat 3.1 (Jandel Scientific Corporation, San Jose, California).
Representative samples of the helminths collected during this study were deposited in the Helminthological Collection of the Instituto Oswaldo Cruz (CHIOC – numbers requested) in the state of Rio de Janeiro, Brazil.
Out of 28 green sea turtles, 21 were females, 4 were males and 3 were of undetermined sex. All were juveniles (CCL: 36.9 ± 5.6 ranging from 27.9 to 51.2 cm; weight: 4.5 ± 1.2 ranging from 2.6 to 6.4 kg). All green sea turtles were positive for helminths. A total of 14802 trematodes belonging to 30 species and 5 families, including Microscaphidiidae (9 species), Plagiorchiidae (3 species), Pronocephalidae (15 species), Hapalotrematidae (2 species) and Telorchiidae (1 species), were recovered (Table 1). In addition, an unidentified nematode larva was found in two turtles. The mean intensity was 536 (95% CI = 362 – 853) (range: 1 – 2831), the mean abundance was 536 (95% CI = 364 – 850), and the species richness was 7.86 (95% CI = 6.46 – 9.21) (range: 1 – 17).
Prevalence, mean intensity, and mean abundance of helminths parasites identified in Chelonia mydas (n=28) from the Rio de Janeiro State, Brazil.
Species | Number of parasites | Site of infection | % Prevalence (95% CI) | Mean abundance (95% CI) | Mean intensity (95% CI) |
---|---|---|---|---|---|
Microscaphidiidae | |||||
33 | Si | 3.6 (0.2–17.5) | 1.18 (0–3.54) | 33 | |
63 | Si, Li | 25 (11.9–44.6) | 2.25 (0.5–6.45) | 9 (2.86–19) | |
87 | St, Li | 7.1 (1.3–22.9) | 3.11 (0–11.9) | 43.5 (14–73) | |
22 | Li | 7.1 (1.3–22.9) | 0.786 (0–2.18) | 11 (9–11) | |
2 | Li | 3.6 (0.2–17.5) | 0.0714 (0–0.214) | 2 | |
207 | Si, Li | 39.3 (22.9–59.1) | 7.39 (3.5–13.8) | 18.8 (10.6–29.1) | |
124 | St, Si, Li | 14.3 (5–31.9) | 4.43 (0.179–20.9) | 31 (2–87.5) | |
9 | Si | 3.6 (0.2–17.5) | 0.321 (0–0.964) | 9 | |
335 | St, Si, Li | 28.6 (14.2–48.2) | 12 (3.14–46.4) | 41.9 (14.6–116) | |
Plagiorchiidae | |||||
1 | Si | 3.6 (0.2–17.5) | 0.0357(0–0.107 | 1 | |
3 | Si | 7.1 (1.3–22.9) | 0.107 (0–0.321) | 1.5 (1–1.5) | |
39 | St, Si | 25 (11.9–44.6) | 1.39 (0.357–4.76) | 5.57 (1.86–15) | |
Pronocephalidae | |||||
38 | Es, St, Li | 17.9 (7.3–35.7) | 1.36 (0.214–5.68) | 7.6 (1.8–23.4) | |
2 | St | 3.6 (0.2–17.5) | 0.0714 (0–0.214) | 2 | |
4,275 | Es, St, Si, Li | 89.3 (71.8–97) | 153 (93.9–300) | 171 (105–334) | |
120 | St, Si | 32.1 (17.5–51.8) | 4.29 (1.61–11.6) | 13.3 (6.22–29.4) | |
5 | St | 14.3 (5–31.9) | 0.179 (0.0357–0.357) | 1.25 (1–1.5) | |
1,333 | Es, St, Si, Li | 82.1 (64.3–92.7) | 47.6 (30.3–81.8) | 58 (37.5–95.1) | |
51 | Si | 10.7 (3–28.2) | 1.82 (0.214–7.97) | 17 (3–29.3) | |
533 | Es, St, Si, Li | 35.7 (19.3–55.4) | 19 (6.46–48.4) | 53.3 (18.1–117) | |
22 | Si | 7.1 (1.3–22.9) | 0.786 (0–3.75) | 11 (1–11) | |
72 | Es, St, Si | 25 (11.9–44.6) | 2.57 (0.786–9.58) | 1033 (4–27.5) | |
339 | St, Si, Li | 46.4 (28.2–64.5) | 12.1 (3.89–30.6) | 26.1 (9.46–59.9) | |
974 | Es, St, Si, Li | 82.1 (64.3–92.7) | 34.8 (22.3–63.2) | 42.3 (27.3–72.4) | |
79 | St, Si, Li | 14.3 (5–31.9) | 2.82 (0.643–7.5) | 19.8 (9–31.5) | |
3,472 | Es, St, Si, Li | 53.6 (35.5–71.8) | 124 (19.8–534) | 231 (36.1–945) | |
2,493 | Es, St, Si, Li | 75 (55.4–88.1) | 89 (42.3–183) | 119 (60.9–229) | |
Hapalotrematidae | |||||
1 | Li | 3.6 (0.2–17.5) | 0.0357 (0–0.107) | 1 | |
3 | Li | 3.6 (0.2–17.5) | 0.107 (0–0.321) | 3 | |
Telorchiidae | |||||
9 | Si | 14.3 (5–31.9) | 0.321 (0.0714–0.821) | 2.25 (1–3.25) | |
Nematode larvae | 3 | St, Si | 7.1 (1.3–22.9) | 0.107 (0–0.357) | 1.5 (1–1.5) |
The present study reports the highest prevalence, mean intensity of infection and species richness when compared to other studies on juvenile green sea turtles in Brazil (Werneck & Silva, 2015; Binoti
This finding together to different component community than previous studies (Werneck & Silva, 2015; Binoti
Trematodes were the predominant class of parasites in the juvenile green turtles, as expected. All species identified have been previously reported in the same host. However,
Only 4 species of parasites were found in more than 50 % of the animals analyzed:
Sixteen (57 %) carcasses were in poor body condition; the remaining turtles were in good or fair condition. In this latter group the cause of death was drowning. This data confirms that accidental capture remains one of the main threats for this species in the coast of Rio de Janeiro state, as described in a recent study (Tagliolatto
Out of 16 carcasses in poor condition, five had gross esophageal pathological changes characterized by diffuse ulcers with yellowish necrotic caseous exudate obstructing the esophageal lumen. These lesions were associated with massive infection by
No significant statistical differences were found for species richness, abundance, and mean intensity of infection among carcasses of different body condition classes. The present results also suggest that all green sea turtles here studied belonged to the same population, as there were no differences in composition of parasite fauna or statistical values.