MENGE, B. A.: Environmental Stress, Bottom-up Effects and Community Dynamics: Molecular-Physiological Approaches Open New Vistas

Environmental stress and nutrient/productivity models predict the responses of community structure along gradients of physical factors and bottom-up effects. Although both models have succeeded in helping to understand variation in ecological communities, most tests have been qualitative. Until recently, two roadblocks to more quantitative tests in marine environments have been a lack of (1) inexpensive, field-deployable technology for quantifying (e.g.) temperature, light, salinity, chlorophyll, and productivity, and (2) methods of quantifying the sub-organismal mechanisms that linked environmental conditions to their ecological expression. The advent of inexpensive remote-sensing technology, adoption of molecular techniques such as quantification of heat-shock proteins, ubiquitin conjugates, and RNA:DNA ratios, and the formation of interdisciplinary alliances between ecologists and physiologists has begun to overcome these roadblocks. An integrated eco-physiological approach focuses on the determinants of: distributional limits along (local-scale) environmental gradients (e.g., zonation), among-site (mesoscale) differences in community pattern, and geographic (macroscale) differences in ecosystem structure. These new approaches offer the promise of insight into the molecular and cellular mechanisms underlying variation in processes such species interactions, disturbance, survival and growth. Examples of the power of the new approach include responses of: predation to wave-force stress, a whelk-mussel interaction to physiological stress and food input, and competing mussels to gradients in stress and food concentration.