Host biological factors and geographic locality influence predictors of parasite communities in sympatric sparid fishes off the southern Italian coast

Abstract

Host biological factors and habitat influence the faunal assemblages and biodiversity worldwide, including parasite communities of vertebrate and invertebrate hosts. The ecological relationship between hosts and parasites can be mediated by interaction of host's biological factors, as their physiological condition, diet and size, with the environmental components, somehow influencing the features of parasite infection in host populations. Here, we used boosted regression tree models to study the parasite communities of two sympatric sparid fishes, the salema Sarpa salpa and the white seabream Diplodus sargus, to investigate the role of specific host's traits in two contiguous coastal areas along the southern-western Tyrrhenian coast of Italy characterized by different degree of deterioration. Results showed that overall and across all parasite groups (ecto-, endo-and ectoplus endo-parasites), sampling localities were the most important predictors of abundance, species richness, and diversity for salema. Moreover, seasonality was the main predictor of endo-parasite abundance, while size-related factors explained most of the variation in species richness and diversity. In the white seabream, size-related factors and reproductive cycle-related factors were the most important predictors for the overall parasite abundance and parasite richness, respectively. Our findings suggest that the parasite community of salema and white seabream responded differently to specific biological factors, highlighting how the environmental conditions under which they live may exert a strong influence on the parasite communities of each host fish.

A molecular and ecological study of Grillotia (Cestoda: Trypanorhyncha) larval infection in small to mid‐sized benthonic sharks in the Gulf of Naples, Mediterranean Sea

“…adenoplusia (Dallares et al., 2017 ), with a prevalence of infection ranging from 7.6% to 28.6% and a maximum mean abundance of 0.48 depending from the sampling localities, whereas no Grillotia specimens were detected in 41 individuals of S. canicula from the same locality (Dallares, Padros et al, 2017 ; Dallares et al., 2017 ). The difference in infection values between the North‐Western Mediterranean studies (Dallares, Padros et al, 2017 ; Dallares et al., 2017 ) and the present one might be related to the different geographical features and high productivity in terms of food webs at the time of the sampling, two variables that may affect the number of intermediate and definitive hosts present in the area (Collins et al., 1984 ; Dallares, Padros et al., 2017 ; Hassan et al., 2002 ; Palm & Overstreet, 2000 ; Santoro et al., 2019 ; Santoro, Iaccarino et al., 2020 ).…”

“…Boosted regression trees (BRTs) were then used to model the relationship between the number of Grillotia specimens found in each host with both morphological (FL, weight, and BCI) and physiological predictors (age, sex, SMS, GSI, and HSI) (Santoro, Iaccarino et al., 2020 ). BRTs are a class of nonparametric machine learning method where regression trees are combined in an ensemble boosting algorithm to improve predictive performance.…”

“…Understanding the factors that determine the occurrence or level of infection in marine fishes has interested scientists for decades and numerous variables about parasite, host, and environment have been identified as important in the dynamics of the host–parasite systems (Dallarés, 2016 ; Palm, 2004 ; Santoro, Iaccarino et al., 2020 ; Timi & Poulin, 2020 ; Tompkins et al., 2011 ). In particular, the probability to become infected with larval forms of trypanorhynchans, as well as their levels of infection, depends on a number of biotic and abiotic factors at different geographical scales (Palm, 2004 ; Palm et al., 2017 ; Palomba, Santoro et al., 2021 ; Santoro et al., 2020 ).…”

“…For parasites with a life cycle embedded within the marine food webs, biotic factors are also important to evaluate the physiological condition of the fish and the way the fish get resources from the environment, and also the probability for a host to acquire parasites. Therefore, the study of relationships between biotic factors and number of parasites within a host might also provide information about the biology and ecology of both hosts and parasites (Dallares, 2016 ; Dallares et al., 2016 , 2017 ; Dallares, Padros et al, 2017 ; Palm, 2004 ; Santoro, Iaccarino et al., 2020 ; Timi & Poulin, 2020 ).…”

Insights into the role of deep-sea squids of the genus Histioteuthis (Histioteuthidae) in the life cycle of ascaridoid parasites in the Central Mediterranean Sea waters

“…Host-species interaction through food webs allows transmission and maintenance of biological cycles of most of the parasites in marine ecosystems 13 , 14 . Parasites constitute an important component of every marine community showing a high diversity in their life-cycles 15 – 17 . Cephalopods, as intermediate or paratenic hosts in the life cycle of heteroxenous parasites, can accumulate them throughout their lifespan, thus increasing the chance of predation by the next host and, consequently, the probability of parasite transmission.…”