TITLE PAGE - acumen - The University of Alabama
TITLE PAGE - acumen - The University of Alabama
TITLE PAGE - acumen - The University of Alabama
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and surface streams (20-35,000 g m -2 ; Jones, 1997), indicating that Bluff River Cave was a cave<br />
stream ecosystem that received minimal allochthonous inputs <strong>of</strong> organic matter. While the litter<br />
amendment significantly increased mean organic matter storage within the manipulation reach<br />
(423 g AFDM m -2 ), the level was not higher than those reported from other cave streams within<br />
close geographic proximity (~30 km) to Bluff River Cave (see Huntsman et al., 2011 a, b;<br />
Venarsky et al., 2012; see Chapter 5). Thus, the litter amendment did not increase energy levels<br />
beyond the range <strong>of</strong> that experienced by communities in nearby cave streams.<br />
Facultative species<br />
<strong>The</strong> significant increase in consumer biomass following the litter amendment was driven<br />
by facultative species, which generally dominated consumer biomass both before and after the<br />
litter amendment. <strong>The</strong> strong response by facultative species was likely driven by a combination<br />
<strong>of</strong> dispersal, reproduction, and growth, depending on taxon. While the dispersal patterns <strong>of</strong><br />
facultative species in cave streams are not generally known, their dispersal abilities in surface<br />
streams have been well documented. Many macroinvertebrate insects and crustaceans (e.g.<br />
amphipods) in surface streams are capable <strong>of</strong> dispersing both upstream and downstream several<br />
meters per day due to both density-dependent and -independent factors (Turner and Williams<br />
2000; Elliott 2003). A study by Weingartner (1977) found that the facultative cave crayfish<br />
Cambarus laevis had a wide range <strong>of</strong> movement patterns in an Indiana cave stream, ranging from<br />
65 m day -1 . Surface species <strong>of</strong> Eurycea also tend to drift downstream after hatching<br />
(see Stoneburner 1978; Bruce 1986) and the number <strong>of</strong> individuals drifting from a stream reach<br />
can be influenced by prey availability (Johnson and Wallace 2005). Thus, the colonization <strong>of</strong> the<br />
manipulation reach by facultative species likely occurred from habitats both upstream and<br />
downstream <strong>of</strong> the study reaches. Additionally, the biomass <strong>of</strong> surface stream macroinvertebrate<br />
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