Department of Integrative Marine Ecology, Stazione Zoologica Anton Dohrn, Villa Comunale 1, 80121, Naples, Italy.
Department of Agriculture and Forest Sciences, University of Viterbo, Via San Camillo de Lellis Snc, 01100, Viterbo, Italy.
Sci Rep. 2022 Jun 15;12(1):9969. doi: 10.1038/s41598-022-14024-0.
Sharks play a key role in the functioning of marine ecosystems and maintenance of trophic web balance, including life cycles of parasites co-occurring in their habitats. We investigated the structure of parasite communities of three sympatric shark species (Etmopterus spinax, Galeus melastomus, and Scyliorhinus canicula) and explored both the influence of host features in shaping the communities and their role as biological indicators of environment stability in the Gulf of Naples (central Mediterranean Sea), a geographical area characterized by strong anthropic pressure. Parasites found were all trophic transmitted helminths with a complex life cycle, except Lernaeopoda galei, that is a ecto-parasite copepod. Communities were all similarly impoverished with 4-5 component species and low values of species richness and diversity. Higher abundance of cestode larvae of the genus Grillotia was found in G. melastomus, although their dominance in all host species suggests that the three sharks have a similar role as intermediate/paratenic hosts in local food webs. Similarly, high abundance of Grillotia larvae could also suggest the occurrence of high abundance of largest top predators in the area. Host morphological (fork length in S. canicula and G. melastomus and body condition index in G. melastomus) and physiological (sex and gonadosomatic and hepatosomatic indices in S. canicula) variables were differently correlated to parasite community structures depending by host species. Potential reasons for the present impoverished parasite communities are discussed.
鲨鱼在海洋生态系统的功能和营养网平衡的维持中起着关键作用，包括它们栖息地中寄生虫的生命周期。我们调查了三种共生鲨鱼物种（Etmopterus spinax、Galeus melastomus 和 Scyliorhinus canicula）的寄生虫群落结构，并探讨了宿主特征对群落结构的影响及其作为那不勒斯湾（地中海中部）环境稳定性的生物指标的作用，该地区受强烈人为压力的影响。发现的寄生虫都是营养传播的吸虫，具有复杂的生命周期，除了 Lernaeopoda galei，它是一种外寄生虫桡足类。群落都同样贫乏，有 4-5 个组成物种，物种丰富度和多样性低。在 G. melastomus 中发现了更多的 Grillotia 属绦虫幼虫，尽管它们在所有宿主物种中的优势表明这三种鲨鱼在当地食物网中具有相似的中间/副宿主作用。同样，Grillotia 幼虫的高丰度也可能表明该地区最大的顶级捕食者的数量较高。宿主形态学（Scyliorhinus canicula 的叉长和 G. melastomus 的身体状况指数以及 G. melastomus 的性腺和肝体指数）和生理学（Scyliorhinus canicula 的性别和性腺体和肝体指数）变量因宿主物种而异，与寄生虫群落结构相关。讨论了目前寄生虫群落贫瘠的潜在原因。
