Resources, toxicants and climatic variation: Effects of environmental variability and anthropogenic disturbance on phytoplankton communities in the Greater Yellowstone Ecosystem

Empirical and experimental evaluation of ecological processes in aquatic systems can yield tremendous insight into the interactions between humans and their environment. Too often, however, insight gained by scientists is lost in the attempt to transfer information to resource managers and the general public. A major problem in this process is that it is difficult to convey how simple interactions discerned through scientific studies have relevance to the complex real world. A novel multidisciplinary approach to this issue that is wide in ecological scope but focused on a single region (the Greater Yellowstone Ecosystem) is employed here to demonstrate a potential solution. This is a four part case study of phytoplankton responses to the environment that addresses critical environmental issues including climate change, multiple environmental stresses, aquatic toxicology, atmospheric contamination and ecological modeling, all focusing on an area which is known for both its natural beauty and its highly charged political issues. Each particular piece of the study is relatively simple and independently coherent. This makes the approaches outlined here Ideal for separate or combined application to other areas and other sets of issues. The first investigation outlined the connections between ENSO, local hydrology and aquatic ecological processes in Yellowstone area lakes. A second investigation of associations among sediment chemistry and fossil diatom composition demonstrated long term increases in N loading and decadal scale regulation of diatom community composition by resource availability. A third study utilizing algal growth inhibition bioassays and non-linear modeling demonstrated that ambient levels of Cu in regional waters are sufficient to inhibit phytoplankton growth. The final experimental study using batch and semi-continuous culture methods with phytoplankton communities demonstrated significant interactions between the combined stresses of resource limitation and metal toxicity in phytoplankton communities of this region and in pelagic systems in general. A combined interpretation of these studies suggests that complex interactions between climate change, atmospheric N loading and toxic metals are affecting ecological processes in relatively pristine environments. Developing adequate qualitative and quantitative models of the mechanistic interactions between humans and their environment may often require exactly such a complex combination of simple scientific approaches.