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Resource supply Mean breakdown rates used to estimate organic matter supply rates were 2.2 yr -1 (1.3-3 yr -1 ; 95% confidence interval) and 0.6 yr -1 (0.4-0.8 yr -1 ; 95% confidence interval; Table 1) for leaf-litter and wood, respectively. Using leaf-litter breakdown rates, mean organic matter supply rates were lowest in Hering (47 g AFDM m -2 yr -1 ) and highest in Tony Sinks (284 g AFDM m -2 yr -1 ; Fig. 2A; Table 5). Using the wood breakdown rates, mean organic matter supply rates were lowest in Hering (13 g AFDM m -2 yr -1 ) and highest in Tony Sinks (80 g AFDM m -2 yr -1 ; Fig. 2A; Table 5). Using a P:B ratio of 5, mean macroinvertebrate production was lowest in Hering (0.13 g AFDM m -2 yr -1 ) and highest in Tony Sinks (1.61 g AFDM m -2 yr -1 ; Fig. 2B; Table 5). The large amount of variability in resource standing stocks translated into wide confidence intervals in the resource supply rates (Fig. 2A, B). Trophic basis of production Mean net production efficiency used to estimate energetic demands for O. australis was 0.46 (0.38-0.54; 95% confidence interval; Table 2). Assuming a diet composed only of organic matter, demand by O. australis was lowest in Limrock (0.47 g AFDM m -2 yr -1 ) and highest in Tony Sinks (7.4 g AFDM m -2 yr -1 ; Fig. 2A; Table 5). Crayfish demand was significantly lower than wood and leaf supply rates in all caves (Fig. 2A,C). Assuming O. australis consumed only macroinvertebrates, mean demand was lowest in Limrock (0.06 g AFDM m -2 yr -1 ) and highest in Tony Sinks (0.9 g AFDM m -2 yr -1 ; Fig. 2B, Table 5). Crayfish demand was similar to prey supply in Hering and Tony Sinks and was significantly lower than prey supply in Limrock (Fig. 2B, D). The inclusion of zero in the 95% confidence intervals for the macroinvertebrate surpluses in Hering and Tony Sinks suggests that the demand by O. australis is not significantly different from supply and does not verify the presence of a resource deficit (Fig. 2D). 111
Discussion The energy-limitation hypothesis The results of this study provided general support for the energy-limitation hypothesis in cave ecosystems. First, the patterns in the biomass and secondary production of O. australis mirrored the gradients in standing crop organic matter and macroinvertebrate biomass among caves (Fig. 1A, B). Second, the comparisons of resource supply rates and crayfish demand indicate that nearly all macroinvertebrate production would need to be consumed to support the populations, which suggests these populations of O. australis are limited by prey availability. Resource availability The range in standing crop organic matter (22-133 g AFDM m -2 ) within the cave streams in this study falls within the lower range of reports from other cave (0-850 g AFDM m -2 ; Simon & Benfield 2001 & 2002; Venarsky et al., 2012a; Huntsman et al., 2011 a, b; see Chapter 3) and surface streams (20-35,000 g m -2 ; Jones, 1997). The large range in organic matter biomass among the cave streams in this study illustrates that, similar to surface streams, resource inputs can vary greatly. One factor likely contributing to the large variability in organic matter biomass among these cave streams is cave structure, such as the depth of cave and size of voids and fractures in the surrounding bedrock. For example, the higher quantities of organic matter in Tony Sinks Cave were probably the result of strong surface connections. This cave contained several entrances, both vertical and horizontal, that intersected intermittent stream channels. Additionally, large ceiling fissures were present in portions of the cave, below which large deposits of organic matter were observed. 112
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THE INFLUENCE OF ENERGY AVAILABILIT
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ABSTRACT Detritus from surface envi
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LIST OF ABBREVIATIONS AND SYMBOLS m
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NC IL ON U.K. VIAT VIE Fig. North C
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AIC K-S Akaike information criterio
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laboratory work and was an excellen
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LIST OF TABLES TABLE 2.1 TABLE 2.2
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LIST OF FIGURES FIGURE 2.1 (a) Box
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FIGURE 4.3 Growth models for Orcone
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chemolithoautotrophy-based systems;
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ecology, 51, 31-53. Gibert J. & Cul
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CHAPTER 2 EFFECTS OF ORGANIC MATTER
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community structure in cave “pits
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communities and how variation in co
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the different source locations was
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of natural-log transformed data (%
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peak in organic matter in Big Mouth
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Figs. 5a, b). The breakdown rate of
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per litter bag. Similarly, Huntsman
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ags was the greater retention of li
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Historically, limited resource inpu
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Culver, D.C. & Pipan, T. (2009) The
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Merritt, R.W., Cummins, K.W. & Berg
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Table 1. Mean (1 S.D.) macroinverte
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Table 2. Mean (±1 S.D.) daily temp
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Figure 1. (a) Box and whisker plot
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Figure 3. Non-metric multidimension
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Figure 5. Box and whisker plot of l
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streams, while the obligate-cave sp
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More recent observational and exper
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of netting (mesh size 2.5×1.5-cm)
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the two end-members. This conservat
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crop organic matter significantly i
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macroinvertebrate biomass to levels
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and surface streams (20-35,000 g m
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these factors, the stable isotope a
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surface streams. Thus, it is likely
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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
Page 87 and 88: 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
Page 93 and 94: individuals, he predicted that it w
Page 95 and 96: A phylogeographic study by Buhay &
Page 97 and 98: 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
Page 105 and 106: References Anonymous (1999) Cave Sc
Page 107 and 108: Huryn A.D. & Wallace J.B. (1987) Pr
Page 109 and 110: Whitmore N. & Huryn A.D. (1999) Lif
Page 111 and 112: 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
Page 119 and 120: following incidental inputs of orga
Page 121 and 122: Temperature data were not available
Page 123 and 124: minimum (Venarsky et al., 2012b). A
Page 125 and 126: 100% organic matter (i.e., maximum
Page 127: Macroinvertebrate biomass varied si
Page 131 and 132: crayfish captured in most months we
Page 133 and 134: systems is likely high, especially
Page 135 and 136: function of microbial films in grou
Page 137 and 138: Crustacean Biology, 4, 35-54. Momot
Page 139 and 140: Whitmore N. & Huryn A. (1999) Life
Page 141 and 142: Table 2. Assimilation efficiencies
Page 143 and 144: Table 3. Continued Tanypodinae 0.03
Page 145 and 146: 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
Page 151 and 152: characteristics (e.g., higher growt
Page 153 and 154: characteristics, highly efficient p
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