Spatial extent of biotic interactions affects species distribution and abundance in river networks: the freshwater pearl mussel and its hosts

Abstract

Aim At what spatial extent are biotic interactions discernible influences on the distribution and abundance of species in river networks? We address this question with analyses of data from river networks for Margaritifera margaritifera, a freshwater mussel that passes its larval stage attached to a host fish.Location Twenty river networks in Galicia, north-western Spain.Methods A maximum-entropy approach was implemented to model the species' distribution. Geostatistical mixed models were used to analyse the mussel's abundance in dendritic river networks. Predictor variables included the abundance and biomass of host fish (biotic interactions) and abiotic predictors for climate, geology and land-form.Results Maxent models of species distribution were improved by 4.5% in terms of the area under the receiver-operating characteristic curve (AUC) by the inclusion of biotic interactions. Host-fish predictors contributed 63% of the Maxent model prediction of mussel presence. A geostatistical mixed model explained 52% of the variance in mussel abundance when including all the mussel abundance sites in the study area; abiotic predictors had no significance and salmonid biomass and resident trout population density were the only significant biotic predictors, together explaining 2.4% of the variance. An autocovariate representing biotic interactions between mussels and fish explained 11.7% of the variance. Using only sites where migratory host fish were present (n = 149), a mixed model explained more variance (78%) and the contribution from the autocovariate for parasite-host interactions was about three times larger than for the model including all sites (n = 419). The spatial autocorrelation from mussel-fish interactions had a spatial extent (geostatistical range) greater than 15 km.Main conclusions Interactions between mussels and their larval hosts in river networks are manifested in spatial patterns of species distribution and abundance in this region, encompassing 20 river networks. The directional topology of dendritic river networks strongly supports the upstream dispersal of mussels by parasitized host fish as a component of spatial autocorrelation in mussel abundance.

Joint species models reveal the effects of environment on community assemblage of freshwater mussels and fishes in European rivers

“…Based on the results, we hypothesize that mussel distributions are nested within the host fish distributions and that the presence of fish hosts in given communities is driven by both abiotic and biotic factors, while the presence of mussels is primarily driven by local abiotic conditions. Previous studies with a single‐species SDM partially supported this hypothesis, where the breadth of suitable habitats for fish hosts were larger than that of mussels (Inoue et al ., ) and the abundance of fish hosts as a predictor improved the model fitness of SDMs (Lois et al ., ).…”

High‐resolution ecological niche modelling of threatened freshwater mussels in east Texas, USA

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Microhabitat selection in the common lizard: implications of biotic interactions, age, sex, local processes, and model transferability among populations

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