A journey to the deeps of the sea: parasite communities of the alepocephalidae and the macrouridae in the balearic sea (nw mediterranean)
- Autores: David Pérez García
- Directores de la Tesis: Maite Carrassón López de Letona (dir. tes.), María Constenla Matalobos (codir. tes.), Anna Soler Membrives (codir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2017
- Idioma: español
- Tribunal Calificador de la Tesis: Mercedes Fernández Martínez (presid.), Joaquim Castellà Espuny (secret.), Salvatore Mele (voc.)
- Programa de doctorado: Programa de Doctorado en Acuicultura por la Universidad Autónoma de Barcelona y la Universidad de Barcelona
- Materias:
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- Resumen
Despite the great number of studies on the Mediterranean, its deep sea remains largely unknown, especially in relation to its parasite fauna. Parasites are important components of ecosystems. Being ubiquitous throughout all food webs, they can provide significant information of their hosts. In addition, it is expected that host respond to the harmful effects of parasites at different levels. Moreover, histo-cytological alterations and/or variations on the levels of certain biochemical markers can be related to the presence of parasites and are means to evaluate fish health. Since most of the important deep Mediterranean fishes are still largely unknown, their parasites can prove to be valuable sources of information. Alepocephalus rostratus and Macrouridae are important components of the fish community along the deep slope of the Balearic Sea. For this reason, the objectives of the present thesis are to characterize for the first time the parasite communities of Alepocephalus rostratus, and the macrourids Coelorinchus caelorhincus, Coelorinchus mediterraneus, Coryphaenoides guentheri and Coryphaenoides mediterraneus, their natural variability and their effects on fish health in the Balearic Sea. In addition, the relationship between the trophic profile of hosts and parasite communities will be discussed. The parasite communities of A. rostratus were constituted by little number of species (seven metazoan species and one coccidian). Low richness together with the high proportion of parasite larval forms are usually characteristic of meso- and bathypelagic fish species. This is probably due to the specialized diet of A. rostratus on planktonic organisms. The larval tetraphyllideans and cucullanid nematodes were the predominant species. A positive relationship was found between acetylcholinesterase activity and Tetraphyllidea fam. gen. sp., Anisakis physeteris and H. aduncum abundance and a negative one with the abundance of Cucullaninae gen. sp. Lactate dehydrogenase showed a positive relationship with the abundance of the parasites Paracyclocotyla cherbonnieri and Tetraphyllidea fam. gen. sp. Coccidians were detected in the pyloric caeca with a prevalence of 90% in Barcelona. A total of 11 parasite taxa were found among the four macrourids studied, being the copepod Hamaticolax resupinus the only parasite shared by all of them. Coelorinchus mediterraneus, C. guentheri and Cor. mediterraneus exhibited rather homogeneous parasite communities, especially in the case of the latter two, probably due to their similar diet composition. Coelorinchus mediterraneus showed the highest richness of parasite taxa (eight species), whereas C. guentheri and Cor. mediterraneus harboured up to five and six, respectively, and C. caelorhincus up to three. Several of the encountered parasites occurred at very low prevalence (<10%), while only three species were exceptionally prevalent and abundant: Cucullanidae fam. gen. sp. larvae in C. caelorhincus; Lepidapedon desclersae in Coe. mediterraneus and Hysterothylacium aduncum in both Coryphaenoides spp. Few parasite effects on fish health were reflected at enzymatic and histological level, probably due to the low parasite burden in their hosts. Hamaticolax resupinus n. sp. is described for the first time from Coe. mediterraneus and Cor. mediterraneus. It is the second Hamaticolax species that parasitizes a macrourid species and it is the deepest bomolochid encountered worldwide. Hamaticolax resupinus is smaller than its closely related species H. maleus, females have wider genital double-somite markedly wider than free abdominal somites and with convex lateral margins. Raphidascaris (R.) macrouri n. sp. is described for the first time from the deep Mediterranean macrourids Nezumia aequalis and Trachyrincus scabrus. This species differentiates from the rest of the subgenus by having high number of caudal papillae and short spicules.
