R3 PM Application of Spatially Explicit Techniques in Ecological Risk Assessment
Thursday, 17 November 2005: 1:50 PM - 5:30 PM in Ballroom 3

(AKC-1117-638251) Effect of spatial heterogeneity on assessing population-level ecological risks.

Akcakaya, H. R.¹, ¹ Applied Biomathematics, Setauket, NY, USA

ABSTRACT- Assessing ecological risks at the population-level requires estimating endpoints such as risk of population decline, chance of recovery, and the distribution of future population sizes and growth rates. When the spatial distribution of the individuals, or the threats faced by the species are heterogeneous, such endpoints may depend sensitively on how these spatial heterogeneities are incorporated into the models used in the assessments. Spatial heterogeneities in the environment can be incorporated into (or ignored by) models at various levels of detail. In this talk, the relative importance of these levels of complexity and interactions are reviewed with examples, and the types of models that incorporate spatial structure for population-level ecological risk assessment are discussed. At the most basic level, a model can assume a single panmictic population, or a metapopulation with multiple (sub)populations. At a finer level, a metapopulation model might assume that all populations have identical parameters (such as survival, fecundity, carrying capacity, etc.) or it can incorporate population-specific values for these parameters. At the finest level, the metapopulation model can take location of each population into account, incorporating spatial variation in the interactions among populations (e.g., dispersal and spatial autocorrelation), for example by making these functions of the distance and habitat between the populations. In addition, there may be interactions between temporal and spatial heterogeneity in the form of temporal trends or random changes in spatial structure (for example, due to habitat dynamics, or time course of toxicity). Risk assessment examples from ecotoxicology and conservation will be used to illustrate the importance of spatial heterogeneity at these different levels.

Key words: metapopulation, population-level, risk assessment, spatial structure