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For example, a regression analysis of data reported by Simon & Benfield (2001) revealed no significant relationship between organic matter abundance and litter breakdown rates among the five cave streams they studied (M. P. Venarsky, unpubl. analysis). Similarly, Huntsman, Venarsky & Benstead (2011a) found no correlation between organic matter abundance and carrion breakdown rates in four cave streams, suggesting that factors additional to the abundance of organic matter influence rates of carrion processing in caves. Here, the linkages among organic matter abundance (i.e. a surrogate for resource supply), the structure of litter macroinvertebrate communities and litter breakdown rates during two seasonal periods were examined in four cave streams in northeastern Alabama and southeastern Tennessee, U.S.A. These ecosystems contained different amounts of organic matter, allowing the test of three related hypotheses. First, macroinvertebrate abundance is often higher in groundwater systems receiving high inputs of organic matter compared with those receiving low inputs (Datry et al., 2005). Thus, macroinvertebrate biomass in litter packs was hypothesized to be positively correlated with ambient organic matter abundance because caves with higher quantities of organic matter are likely to support more macroinvertebrates. Second, because positive correlations between litter breakdown rates and consumer biomass have been shown for cave and surface streams (Simon & Benfield, 2001; Hieber & Gessner, 2002), litter breakdown rate was predicted to be positively correlated with consumer biomass. Third, because many environmental characteristics in cave systems vary little temporally (e.g. light, humidity and temperature; Juberthie, 2001; Culver & Pipan, 2009), consumer biomass and the rate of litter breakdown was also predicted to vary temporally. The design of this study allowed the quantification of how organic matter abundance affects cave stream macroinvertebrate 9
communities and how variation in community structure affects rates of organic matter processing, a key ecosystem process in cave and groundwater ecosystems. Methods Study sites Four streams in hydrologically separate cave systems were studied. Tony Sinks, Salt River and Jess Elliot caves are in Jackson County, Alabama, U.S.A. Big Mouth Cave is in Grundy County, Tennessee, U.S.A. Distances between caves ranged from 9 km to 76 km. These caves were chosen for the following four reasons. First, their communities appeared similar in structure upon initial inspection (i.e. they all contained cave salamanders and isopods and cave and surface crayfish). Second, organic matter abundance differed among caves due to differing connectivity to surface systems. Third, visual surveys of surface habitats in the recharge area of each cave suggested human disturbance was minimal (e.g. no clear-cuts, little residential development and few roads within the study catchments). Lastly, physical characteristics of the study reaches within and among cave streams were similar. Stream width ranged between 5 and 10 m, while depth ranged from 20 to 80 cm and the substratum was composed of a mixture of sand and gravel interspersed with exposed areas of bedrock. All study reaches were between 200 and 600 m (horizontally) from the nearest known cave entrance and ranged from 70 to 90 m in length. Cave streams did not have known direct aquatic connections (e.g. upstream cave entrances) to surface habitats during base-flow conditions. Litter colonization and breakdown rates Rates of litter breakdown were measured using bags containing red maple (Acer rubrum L.) and corn (Zea mays L.) litter. Choice of these two species allowed us to examine the effects of litter quality on breakdown rate; both species breakdown relatively rapidly (Webster & 10
Page 1 and 2: THE INFLUENCE OF ENERGY AVAILABILIT
Page 3 and 4: ABSTRACT Detritus from surface envi
Page 5 and 6: LIST OF ABBREVIATIONS AND SYMBOLS m
Page 7 and 8: NC IL ON U.K. VIAT VIE Fig. North C
Page 9 and 10: AIC K-S Akaike information criterio
Page 11 and 12: laboratory work and was an excellen
Page 13 and 14: LIST OF TABLES TABLE 2.1 TABLE 2.2
Page 15 and 16: LIST OF FIGURES FIGURE 2.1 (a) Box
Page 17 and 18: FIGURE 4.3 Growth models for Orcone
Page 19 and 20: chemolithoautotrophy-based systems;
Page 21 and 22: ecology, 51, 31-53. Gibert J. & Cul
Page 23 and 24: CHAPTER 2 EFFECTS OF ORGANIC MATTER
Page 25: community structure in cave “pits
Page 29 and 30: the different source locations was
Page 31 and 32: of natural-log transformed data (%
Page 33 and 34: peak in organic matter in Big Mouth
Page 35 and 36: Figs. 5a, b). The breakdown rate of
Page 37 and 38: per litter bag. Similarly, Huntsman
Page 39 and 40: ags was the greater retention of li
Page 41 and 42: Historically, limited resource inpu
Page 43 and 44: Culver, D.C. & Pipan, T. (2009) The
Page 45 and 46: Merritt, R.W., Cummins, K.W. & Berg
Page 47 and 48: Table 1. Mean (1 S.D.) macroinverte
Page 49 and 50: Table 2. Mean (±1 S.D.) daily temp
Page 51 and 52: Figure 1. (a) Box and whisker plot
Page 53 and 54: Figure 3. Non-metric multidimension
Page 55 and 56: Figure 5. Box and whisker plot of l
Page 57 and 58: streams, while the obligate-cave sp
Page 59 and 60: More recent observational and exper
Page 61 and 62: of netting (mesh size 2.5×1.5-cm)
Page 63 and 64: the two end-members. This conservat
Page 65 and 66: crop organic matter significantly i
Page 67 and 68: macroinvertebrate biomass to levels
Page 69 and 70: and surface streams (20-35,000 g m
Page 71 and 72: these factors, the stable isotope a
Page 73 and 74: surface streams. Thus, it is likely
Page 75 and 76: subsides to ecosystem dynamics have
Page 77 and 78:
populations. Journal of Applied Eco
Page 79 and 80:
Poulson T.L. & Lavoie K.H. (2001) T
Page 81 and 82:
Wood P., Gunn J. & Perkins J. (2002
Page 83 and 84:
Table 2. Mean (±1 standard deviati
Page 85 and 86:
Table 2. Continued Chironomini Para
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Figure 1. Mean (bars are standard e
Page 89 and 90:
Figure 3. Non-metric multidimension
Page 91 and 92:
CHAPTER 4 REXAMINING EXTREME LONGEI
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individuals, he predicted that it w
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A phylogeographic study by Buhay &
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differences in size structure among
Page 99 and 100:
and females in Tony Sinks Cave were
Page 101 and 102:
Estimates of life span for O. austr
Page 103 and 104:
available size-classes were well re
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References Anonymous (1999) Cave Sc
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Huryn A.D. & Wallace J.B. (1987) Pr
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Whitmore N. & Huryn A.D. (1999) Lif
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Table 2. Estimated life span (years
Page 113 and 114:
Figure 1. Annual growth increment (
Page 115 and 116:
Figure 3. Growth models for Orconec
Page 117 and 118:
CHAPTER 5 CONSUMER-RESOURCE DYNAMIC
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following incidental inputs of orga
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Temperature data were not available
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minimum (Venarsky et al., 2012b). A
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100% organic matter (i.e., maximum
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Macroinvertebrate biomass varied si
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Discussion The energy-limitation hy
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crayfish captured in most months we
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systems is likely high, especially
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function of microbial films in grou
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Crustacean Biology, 4, 35-54. Momot
Page 139 and 140:
Whitmore N. & Huryn A. (1999) Life
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Table 2. Assimilation efficiencies
Page 143 and 144:
Table 3. Continued Tanypodinae 0.03
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Table 5. Estimates of mean wood and
Page 147 and 148:
Figure 1. (A) Box and whisker plot
Page 149 and 150:
CHAPTER 6 OVERALL CONCLUSIONS Due t
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characteristics (e.g., higher growt
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characteristics, highly efficient p
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