Intestinal helminth fauna of striped dolphins (Stenella coeruleoalba) in the western Mediterranean: No effects of host body length, age and sex

Abstract

The intestine of 52 (28 males and 24 females) striped dolphins (Stenella coeruleoalba) from western Mediterranean waters was examined for helminths. Animals were found stranded along the Spanish coasts during the morbillivirus epizootic in 1990. In accordance with observations from other pelagic tetrapods, including cetaceans from other geographical regions, the intestinal helminth community was depauperate. Four helminth species were found: three tetrabothriid cestodes, Tetrabothrius forsteri (prevalence: 96.2%; mean intensity [95% CI]: 47.4 [34.4-68.2]), Trigonocotyle globicephalae (9.6%; 1.8 [1.0-2.2]), and Strobilocephalus triangularis (23.1%; 5.3 [2.9-10.2]), and immature individuals of the acanthocephalan Bolbosoma vasculosum (51.9%; 2.7 [2.0-3.4]). Schluter's variance test indicated a weak, but statistically significant association of occurrence of helminth species in dolphins, suggesting that some tetrabothriid species might use the same intermediate or paratenic hosts. Neither the abundance of helminth species nor infracommunity descriptors were significantly affected by sex, host body length or age. The absence of predictable effects of body size and age on the recruitment rate of helminths could be related to the fact that the host sample was largely composed of adults. This study provides quantitative evidence about helminth community structure of striped dolphins, based on a large sample size.

Dolphins Stranded along the Tuscan Coastline (Central Italy) of the “Pelagos Sanctuary”: A Parasitological Investigation

“…Overall, all parasite species identified in this study were already reported in previous studies both in dolphins living in the Mediterranean Sea and in other seas [ 12 , 20 , 21 , 22 , 23 ].…”

“…Among cestode species for which dolphins are the definitive hosts ( Table 1 , Figure 3 ), the species Tetrabothrium forsteri (7.69%, 2/26; Figure 3 B1,B2) and Strobilocephalus triangularis (7.69%, 2/26; Figure 3 C) were here identified only in striped dolphins, both with a prevalence of about 13% (2/15). This prevalence is lower than that previously reported [ 20 ]. Both species infect the intestine but, while S. triangularis may be responsible for granulomatous nodular lesions, T. forsteri is considered a low-pathogenic parasite [ 35 ].…”

“…About acanthocephalans, Bolbosoma vasculosum (7.69%, 2/26; Figure 3 E1,E2) was identified in bottlenose dolphins with a prevalence (20.00%, 2/8) lower than that (52.0%) reported by Mateu et al [ 20 ]. These parasites are found in the intestine and are potentially highly pathogenic due to the hooked proboscis, which can cause an intestinal inflammatory reaction with fibrosis [ 33 ].…”

“…After clarification, internal and external structures were visualized under an optical microscope and measured by using a micrometric ocular. Parasite identification was based on morphological identification keys available in the literature [ 11 , 12 , 20 , 23 , 30 , 32 , 35 , 37 , 62 , 63 , 64 , 65 , 66 , 67 ].…”

A Visitor of Tropical Waters: First Record of a Clymene Dolphin (Stenella clymene) Off the Patagonian Coast of Argentina, With Comments on Diet and Metazoan Parasites

“…Interestingly, two main groups of intestinal helminths that could be predicted for cetaceans worldwide, i.e., cestode species of Tetrabothrius and acanthocephalan species of Bolbosoma (see Aznar et al, 2001), are apparently scarce or absent in delphinids of Argentine waters. For example, T. (T.) forsteri which exhibits high specificity mainly for delphinids (Mateu et al, 2014;Fraija-Fernández et al, 2016), has never been reported in the local dolphin populations off the Argentine coast. It seems plausible that this tapeworm species may not be present in this region of the southwestern Atlantic Ocean.…”