Conservation from the bottom up: forecasting effects of global change on dynamics of organic matter and management needs for river networks

Multiple drivers of global environmental change are fundamentally altering essential basal resources, such as detritus. Metabolic processes in most aquatic ecosystems are supported by terrestrial detritus, which contributes to the production of organisms and the energetic stability of ecosystems. We suggest that conservation and management approaches to ecosystems along river networks must incorporate the organic-matter resources that support them. Understanding changes in the dynamics of detrital organic matter is particularly important because the quantity of this resource is decreasing and its qualities are being altered as a result of effects of current global changes. We summarize these effects in lotic ecosystems from reach- to network-scales and suggest future research questions aimed at adding quantitative rigor to our understanding of the interactions between dynamics of organic matter and ecological outcomes. This approach is a necessary next step to address large-scale changes in stream and river ecosystems that derive from fundamental alterations in detrital resources, which propagate through the foodweb base to higher-order consumers and emergent ecosystem properties.