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(±1 mm; snout-vent length for salamanders and ocular carapace length for crayfish) and released
after sampling was completed.
In the laboratory, invertebrates were removed from the core-samples, identified to the
lowest practical taxonomic level and measured to the nearest 1-mm. Biomass was estimated
using length-mass relationships (Calow, 1975; Culver et al., 1985; Leeper & Taylor, 1998;
Benke et al., 1999; Doroszuk et al., 2007; Lemke & Benke, 2009; Huntsman et al. 2011a and b).
Taxa were categorized into functional feeding groups after Merritt et al. (2008). Taxa were also
assigned to either an obligate-cave or facultative-cave life history categories. Obligate cave
species were identified by their lack of eyes and pigment. Some taxa could not be placed into
either category (e.g. oligochaetes, cyclopoids, harpacticoids, ostracods, nematodes, and
cladocerans), however. Organic matter from each sample was dried at 60˚C to constant mass,
weighed and combusted at 500˚C for 6 h. Combusted material was wetted, re-dried and weighed.
The difference between oven-dried mass and ash mass was used to estimate the ash-free dry
mass (AFDM) of organic matter.
Food web analysis
For stable isotope analyses, samples of particulate detritus and consumer tissues were
collected from both study reaches every 1-2 months following the litter amendment. Samples
were transported to the laboratory on ice. Invertebrates were sorted the following day,
lyophilized, and stored at -20˚C until analysis for stable isotope composition (Marine Biological
Laboratory, Stable Isotope Laboratory, Woods Hole, MA, USA and Analytical Chemistry
Laboratory, University of Georgia, Athens, U.S.A.). Data for each consumer group from the
manipulated reach was analyzed using a standard linear mixing model (two-source, singleisotope)
with the δ 13 C of corn litter and the δ 13 C of the same consumer in the reference reach as
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