Environmental variables and definitive host distribution: a habitat suitability modelling for endohelminth parasites in the marine realm

Abstract

Marine nematodes of the genus Anisakis are common parasites of a wide range of aquatic organisms. Public interest is primarily based on their importance as zoonotic agents of the human Anisakiasis, a severe infection of the gastro-intestinal tract as result of consuming live larvae in insufficiently cooked fish dishes. The diverse nature of external impacts unequally influencing larval and adult stages of marine endohelminth parasites requires the consideration of both abiotic and biotic factors. Whereas abiotic factors are generally more relevant for early life stages and might also be linked to intermediate hosts, definitive hosts are indispensable for a parasite’s reproduction. In order to better understand the uneven occurrence of parasites in fish species, we here use the maximum entropy approach (Maxent) to model the habitat suitability for nine Anisakis species accounting for abiotic parameters as well as biotic data (definitive hosts). The modelled habitat suitability reflects the observed distribution quite well for all Anisakis species, however, in some cases, habitat suitability exceeded the known geographical distribution, suggesting a wider distribution than presently recorded. We suggest that integrative modelling combining abiotic and biotic parameters is a valid approach for habitat suitability assessments of Anisakis, and potentially other marine parasite species.

Increasing intensities of Anisakis simplex third-stage larvae (L3) in Atlantic salmon of coastal waters of Scotland

“…The substantial increase in A. simplex (s.l.) intensity in Atlantic salmon over the last 50 years, and differences between geographical regions, are likely due to several biotic and abiotic factors [10]. As Atlantic salmon are opportunistic feeders [16], changes in the availability and distribution of common dietary inputs are likely to cause a change in the dietary composition of wild Atlantic salmon.…”

“…Anisakis simplex (s.s.) intensity within a host is dependent on a number of biotic and abiotic factors at different geographical scales [10]. More specifically, the distribution of L3 and adult stages is generally shaped through biotic factors involved in transmission pathways, such as trophic interrelations between definitive, intermediate and transport hosts and their respective migrating behaviours [11].…”

The Mediterranean European hake, Merluccius merluccius : Detecting drivers influencing the Anisakis spp. larvae distribution

“…Abiotic and biotic factors, such as mean sea surface temperature, depth, salinity, sea surface temperature range, as well as primary production, were identified as most important abiotic variables impacting the distribution of Anisakis spp. (Højgaard, 1998;Kuhn et al, 2016).…”

Inferring the demographic history of an oligophagous grasshopper: Effects of climatic niche stability and host-plant distribution

“…Although the reliability of the two best-supported ENMs is evidenced by the fact that their resulting climate/habitat suitability stability estimates explained spatial patterns of neutral genetic variation of the focal species, our approach aimed to integrate biotic and abiotic interactions into ENMs may present some uncertainties derived from the usage of host-plant potential distributions that are themselves the product of climate-based ENMs (see also Kuhn et al, 2016). However, this source of error is expected to be minimal as host-plant predicted distributions reflected well their respective contemporary observed distributions.…”

“…This is the case of many specialist organisms whose demography is expected to be determined not only by changes in the spatial distribution of climatically suitable areas but also by range shifts experienced by the hosts on which they depend for feeding or development (e.g. Tsai and Manos, 2010;Cangi et al, 2013;Kuhn et al, 2016). Climate-based distributional shifts of host species can have a considerable impact on specialist taxa, particularly if differences in species-specific environmental tolerances result in the responses to climate change of the latter inferred on the basis of bioclimatic niche models are largely uncoupled from those experienced by their hosts (Tsai and Manos, 2010;Borer et al, 2012).…”