Parasites of skipjack, Katsuwonus pelamis, from Madeira, Eastern Atlantic

Factors linked to interannual variation in the metazoan parasite communities of black skipjack, Euthynnus lineatus (Pisces: Scombridae)

“…The parasite communities of E. lineatus exhibited similar patterns at the component and infracommunity levels: high species richness and diversity, and dominance by a single species (the didymozoids A. claviforme or P. yaito ; Table ). Species richness at the component level (14–24 species; Table ) was similar to that reported previously in other small tuna species such as Katsuwonus pelamis (24–26 species), Euthynnus affinis (23 species), and Euthynnus alleteratus (22 species) (Alves & Luque, ; Hermida et al, ; Lester, Barnes, & Habib ; Madhavi & Ram, ). The high diversity and species richness recorded in these tunas’ parasite communities can be attributed to their high vagility, varied diet, long life span, and endothermy, all features that render them highly suitable hosts for helminth parasites (Hermida et al, ; Madhavi & Ram, ).…”

“…Species richness at the component level (14–24 species; Table ) was similar to that reported previously in other small tuna species such as Katsuwonus pelamis (24–26 species), Euthynnus affinis (23 species), and Euthynnus alleteratus (22 species) (Alves & Luque, ; Hermida et al, ; Lester, Barnes, & Habib ; Madhavi & Ram, ). The high diversity and species richness recorded in these tunas’ parasite communities can be attributed to their high vagility, varied diet, long life span, and endothermy, all features that render them highly suitable hosts for helminth parasites (Hermida et al, ; Madhavi & Ram, ). Numerical dominance of didymozoids in tunas is considered a common pattern, because of these parasites’ high infection site specificity and high host‐specificity (Hermida et al, ; Madhavi & Ram, ; Nikolaeva, ).…”

“…Crustaceans were the second‐most diverse parasite group (three copepods and three isopods) and represented 18.2% of total species; however, this group's numerical dominance was quite low (0.28% of total individual parasites). Apparently the crustaceans are not abundant and frequent in scombrid fish; only one to four species (including C. bonito , reported here) have been recorded in the parasite communities of these marine fish (Alves & Luque, ; Chero et al, ; Hermida, Cavaleiro, Gouveia, & Saraiva, ; Mele et al, ).…”

“…The tunas’ high vagility and endothermy require high metabolic energy usage which is met through foraging on large quantities of food items (e.g., crustaceans, fish, molluscs, and polychaetes) that can function as intermediate and paratenic hosts for didymozoid and other helminth parasites (Madhavi & Ram, ). Therefore, the physiological and feeding behavior traits of E. lineatus allow many trophically transmitted parasite species to be accumulated in large quantities throughout their long lifespan (Hermida et al, ; Madhavi & Ram, ; Nascimento‐Justo & Kohn, ). However, variation in aggregation levels among individuals of E. lineatus suggests the existence of differences in host–parasite exposure rates, possibly due to the influence of local environmental factors (Poulin, ; Soares et al, ), particularly changes in water temperature, or differences in host diet composition as indicated in the feeding analysis results.…”

“…The high diversity and species richness recorded in these tunas’ parasite communities can be attributed to their high vagility, varied diet, long life span, and endothermy, all features that render them highly suitable hosts for helminth parasites (Hermida et al, ; Madhavi & Ram, ). Numerical dominance of didymozoids in tunas is considered a common pattern, because of these parasites’ high infection site specificity and high host‐specificity (Hermida et al, ; Madhavi & Ram, ; Nikolaeva, ). For example, as many as fourteen didymozoid species have been recorded in E. affinis ; these include A. claviforme and P. yaito (Madhavi & Ram, ), both reported here as numerically dominant species in E. lineatus .…”