TITLE PAGE - acumen - The University of Alabama

ABSTRACT
Detritus from surface environments supplies the energy that shapes community structure
and fuels productivity in most cave ecosystems. However, only qualitative descriptions of cave
energy dynamics are available, hindering development of quantitative models describing how
energy availability influences cave ecosystem processes. In contrast, the importance of detritus
for surface ecosystem processes has been appreciated for decades. This dissertation begins to
close this knowledge gap by exploring how energy availability shapes cave stream ecosystem
processes at multiple organizational levels (ecosystem-, community-, population-level) and time
scales (evolutionary vs. ecological).
Chapter Two examined potential correlations between litter breakdown rates and detrital
storage, but found no such relationships among four cave streams. However, surface-adapted
species dominated macroinvertebrate biomass, suggesting that surface-adapted taxa can have a
significant influence on cave ecosystem processes. In Chapter Three, a whole-reach litter
amendment was conducted to explore the influence of enhanced detrital inputs on cave
community structure and energy flow. While the litter amendment significantly increased total
consumer biomass via assimilation of amended corn-litter, the response was dictated by
evolutionary history. Biomass of surface-adapted taxa increased significantly following the
amendment, while biomass of obligate cave species remained unchanged. As in Chapter Two,
consumer biomass was dominated by surface-adapted taxa, reinforcing their role in cave
ecosystem processes relative to cave-adapted taxa, the traditional focus of cave studies.
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