6.5 - Diversity, productivity, and invasibility relationships in rock pool food webs

Abstract

This chapter examines a number of statistics to assess community-level resistance and response to invasion events. There has been no agreed upon measure for invasion success and consequences, and therefore several statistics to provide a comparison and contrast of measures on the same experimental data have been used. Data from two studies conducted in the same rock pool ecosystem, but under different experimental invasion conditions, have been compared and contrasted to see if measured responses are robust to differences such as the degree of control over community structure and invader identity. The studies demonstrate that for rock pool invertebrate food webs, species richness across various trophic levels inhibits the success of species invasions, and that this effect does not depend on differences in trophic habits of the invasive species. In the rock pools where competition for nutrient resources occurs, nutrient availability may only inhibit invasions for species with specific trophic habits. While trophic traits of the invasive species appear to be unrelated to whether species richness is an important determinant of invasibility, they do affect whether nutrient limitation plays a role. Invasive species traits such as trophic habits in relation to actual resource availability appear to constrain invasibility. Similarly, the scale at which an invader operates in terms of reproduction and mobility relative to the characteristic scale of the native food web also appears to affect the response of the community to invasion.