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australis are comparable to other estimates for a modest assemblage of both cave and surface species of crayfish for which credible age estimate exist. Regardless, these shorter longevity and time-to-maturity estimates for O. australis are still relatively great compared with surface species in the same genus, indicating that this species has evolved K-selected life history traits and has a high degree of specialization to cave habitats. Support for the energy-limitation hypothesis in cave ecosystems has historically come from either laboratory-based studies focused on individual physiological characteristics (e.g. metabolic rates) of obligate cave species or field-based population- or community-level studies examining for correlations between resource availability and species biomass or productivity. While each approach has its strengths, neither places its results within the context of energy dynamics of actual cave ecosystems (e.g. resource supply rates vs. consumption and growth). In Chapter Five, the mark-recapture data set for O. australis from Chapter Four was combined with both the trophic basis of production approach (sensu Benke & Wallace, 1980) and estimates of resource supply rates (e.g. organic matter and macroinvertebrate prey) to place the energetic demands of O. australis within the context of cave energy dynamics. Similar to the results of Chapter 3, macroinvertebrate biomass increased with organic matter standing stock among the three cave streams. Both the biomass and secondary production of O. australis were positively related to resource standing stocks. The energy budgets showed no indication of resource deficits. The energetic models, however, indicated that nearly all prey production is necessary to support the populations of O. australis, which suggests that inter- and intra-specific competition for resources within these caves is likely high. Thus, the energetic budgets constructed for O. australis in this study provide the first quantitative explanation of why K-selected life history 135
characteristics, highly efficient physiologies, and enhanced sensory systems for food acquisition are an evolutionary advantage to obligate cave species. Collectively, this dissertation represents the most robust examination to date of how energy availability shapes the structure and function of cave communities. On evolutionary time scales the low quantities of energy inputs appear to have influenced the evolution of K-selected life history characteristics (see Chapters 4 and 5). These adaptations likely allow obligate cave species to respond (e.g. increased population size) to long-term (see Chapter 5) rather than shortterm (see Chapter 3) increases in energy availability. Surface-adapted taxa dominated the biomass of cave communities (see Chapters 2 and 3), suggesting that their effects on cave ecosystem processes may be greater than those of cave-adapted taxa, which have been the traditional focus of cave studies. Lastly, this dissertation has demonstrated that some cave and surface (e.g., forested headwater streams) ecosystems are fundamentally similar and appear to be linked to one another along a detrital subsidy spectrum that includes both high (e.g. surface) and low (e.g. cave) rates of detrital inputs (Chapter 3). References Benke A.C. & Wallace J.B. (1980) Trophic basis of production among net-spinning caddisflies in a southern Appalachian stream. Ecology, 61, 108-118. Cooney T.J. & Simon K.S. (2009) Influence of dissolved organic matter and invertebrates on the function of microbial films in groundwater. Microbial ecology, 58, 599-610. Cooper J. (1975) Ecological and behavorial studies in Shelta Cave, Alabama, with emphasis on decapod crustaceans. Ph. D., University of Kentucky. Culver D.C., Kane T.C. & Fong D.W. (1995) Adaptation and natural selection in caves: the evolution of Gammarus minus, Harvard University Press. Graening G.O. & Brown A.V. (2003) Ecosystem dynamics and pollution effects in an Ozark cave stream. Journal of the American Water Resources Association, 39, 1497-1507. Huntsman B.M., Venarsky M.P. & Benstead J.P. (2011a) Relating carrion breakdown rates to 136
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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
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populations. Journal of Applied Eco
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Poulson T.L. & Lavoie K.H. (2001) T
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Wood P., Gunn J. & Perkins J. (2002
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Table 2. Mean (±1 standard deviati
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Table 2. Continued Chironomini Para
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Figure 1. Mean (bars are standard e
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Figure 3. Non-metric multidimension
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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
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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 and 128: Macroinvertebrate biomass varied si
Page 129 and 130: Discussion The energy-limitation hy
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: characteristics (e.g., higher growt
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