Use of a spatially explicit model to study the distributional dynamics of Unionid mussels

The United States has one of the richest and most diverse communities of freshwater mussels in the world. However, since early in this century, anthropogenic activities have had negative impacts on mussel communities. Destruction of natural habitats and reduction in number of fish hosts are some of the more severe effects of man's actions. This has resulted in many species of mussels presently being on the brink of extinction.

For my research purposes, I developed a computer model to test hypotheses concerning the diversity and spatial distribution of the Unionid mussels. The model is a generalized Leslie matrix model formulated for 35 different species with 15 age classes per species. In the model, each species of mussel is parameterized individually with regard to its characteristics and environmental sensitivities. The computer model uses a parallel computing approach and is designed to run on the MasPar MP-2.

Results from simulation runs of the computer model suggest that mussels propagate into new habitats in the form of a traveling wave front. Furthermore, a correlation was discovered linking the speed of the traveling wave front to mussels' characteristics and habitat.

I examined also the role of fish hosts in the spatial distribution of mussels in light of the core-satellite hypothesis. In addition, the characteristics of different mussel communities were investigated to uncover the mechanisms involved in producing a bimodal core-satellite species distribution of mussels.