Modelling and predicting biogeographical patterns in river networks

Sabela Lois

doi:10.21425/f5fbg28878

Abstract

Statistical analysis and interpretation of biogeographical phenomena in rivers is now possible using a spatially explicit modelling framework, which has seen significant developments in the past decade. I used this approach to identify a spatial extent (geostatistical range) in which the abundance of the parasitic freshwater pearl mussel (Margaritifera margaritifera L.) is spatially autocorrelated in river networks. I show that biomass and abundance of host fish are a likely explanation for the autocorrelation in mussel abundance within a 15-km spatial extent. The application of universal kriging with the empirical model enabled precise prediction of mussel abundance within segments of river networks, something that has the potential to inform conservation biogeography. Although I used a variety of modelling approaches in my thesis, I focus here on the details of this relatively new spatial stream network model, thus advancing the study of biogeographical patterns in river networks.

Highlights

I examine the biogeography of the river-dwelling freshwater pearl mussel (Margaritifera margaritifera L.), a species that passes a parasitic larval stage attached to a host fish
Approximately three times more variation in mussel abundance was explained by the downstream-to-upstream perspective in contrast to the upstream-todownstream perspective, which suggests passive downstream processes are more important in determining mussel abundance in river networks
The results indicate an important negative impact of dams excluding migratory host fish from mussel populations

Summary

Introduction

I examine the biogeography of the river-dwelling freshwater pearl mussel (Margaritifera margaritifera L.), a species that passes a parasitic larval stage attached to a host fish. Abundance, anisotropy, dispersal, distribution, geostatistics, host-parasite, river-networks, spatial autocorrelation Previous publications from Lois (2015) include a description of sampling and data collection (Lois et al 2014) and a spatial analysis of mussel abundance (Lois et al 2015) aimed at identifying the relative importance of biotic interactions on the distribution and abundance of the parasitic pearl mussel.

Results

Conclusion