Abstract
Environmental niche modelling is an acclaimed method for estimating species’ present or future distributions. However, in marine environments the assembly of representative data from reliable and unbiased occurrences is challenging. Here, we aimed to model the environmental niche and distribution of marine, parasitic nematodes from the Pseudoterranova decipiens complex using the software Maxent. The distribution of these potentially zoonotic species is of interest, because they infect the muscle tissue of host species targeted by fisheries. To achieve the best possible model, we used two different approaches. The land distance (LD) model was based on abiotic data, whereas the definitive host distance (DHD) model included species-specific biotic data. To assess whether DHD is a suitable descriptor for Pseudoterranova spp., the niches of the parasites and their respective definitive hosts were analysed using ecospat. The performance of LD and DHD was compared based on the variables’ contribution to the model. The DHD-model clearly outperformed the LD-model. While the LD-model gave an estimate of the parasites’ niches, it only showed the potential distribution. The DHD-model produced an estimate of the species’ realised distribution and indicated that biotic variables can help to improve the modelling of data-poor, marine species.
Highlights
Ecological niche modelling (ENM) is a popular tool to examine the ecological and spatial limitations of species[1,2]
The modelled habitat suitability of P. bulbosa was similar to P. decipiens (s.s.) but shifted towards the poles, into colder regions
As a result of data deficiency, the occurrences of this parasite could not be linked to all environmental variables in a meaningful way, the model was exclusively based on land distance, with no other differentiation
Summary
Ecological niche modelling (ENM) is a popular tool to examine the ecological and spatial limitations of species[1,2]. While niche modelling is widely applied and well established for terrestrial species[14,15,16,17], aquatic, especially marine organisms pose additional challenges. For marine species it may be even more difficult to obtain good and meaningful occurrence data than for terrestrial species[18]. Marine endoparasites are harder to observe than other marine organisms, because they are concealed within their host. Their complex life cycles result in a degree of dependency on other organisms. Including parasite occurrence data from intermediate hosts (especially fishes) and definitive host distribution data separately could improve the ENM of marine parasites. Knowledge of the distribution of these parasites is of interest to identify fishing areas at risk for a high parasite load in the respective food fish
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