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A SURVEY OF THE BRANCHIOPODA AND COMMUNITY ASSOCIATES IN ROCK POOLS WITH RESPECT TO ABIOTIC HABITAT PARAMETERS ACROSS OUTCROPS IN WESTERN AUSTRALIA AND NORTHERN AZ, U.S.A. A Thesis Presented to The Graduate Faculty of The University of Akron In Partial Fulfillment of the Requirements for the Degree Master of Science Alissa Calabrese August, 2009 A SURVEY OF THE BRANCHIOPODA AND COMMUNITY ASSOCIATES IN ROCK POOLS WITH RESPECT TO ABIOTIC HABITAT PARAMETERS ACROSS OUTCROPS IN WESTERN AUSTRALIA AND NORTHERN AZ, U.S.A. Alissa Calabrese Thesis Approved: Accepted: _________________________________ _________________________________ Advisor Dean of the College Dr. Stephen C. Weeks Dr. Chand Midha _________________________________ _________________________________ Committee Member Dean of the Graduate School Dr. Peter Lavrentyev Dr. George R. Newkome _________________________________ _________________________________ Committee Member Date Dr. Randall Mitchell _________________________________ Department Chair Dr. Monte Turner ii TABLE OF CONTENTS Page LIST OF TABLES .............................................................................................................. v LIST OF FIGURES ........................................................................................................... vi CHAPTER I. HABITAT CHARACTERISTICS OF EPHEMERAL ROCK POOLS MAY PREDICT THE DISTRIBUTION OF THE CLAM SHRIMP, LIMNADIA BADIA.......... 1 Introduction ............................................................................................................. 1 Methods................................................................................................................... 4 Results ..................................................................................................................... 7 Discussion ............................................................................................................. 15 II. ALGAL AND BACTERIAL DISTRIBUTION AND ABUNDANCE IN EPHEMERAL POOLS IN RELATION TO CLAM SHRIMP PRESENCE, INCLUDING A COMPARISON OF COMMUNITIES IN WESTERN AUSTRALIA AND ARIZONA, U.S.A. .................................................................................................. 22 Introduction ........................................................................................................... 22 Methods................................................................................................................. 24 Results ................................................................................................................... 26 Discussion ............................................................................................................. 32 Conclusion ............................................................................................................ 38 III. HATCHING CUES IN CLAM SHRIMP: A LABORATORY TEST OF TEMPERATURE AS A MEANS OF SPECIES SEPARATION AND A SUGGESTED ALTERNATIVE MECHANISM FOR THE BET-HEDGING HYPOTHESIS .................................................................................................................. 40 iii Introduction ........................................................................................................... 40 Methods................................................................................................................. 42 Results ......................................................................................................................................... 43 Discussion ............................................................................................................. 46 Conclusion ............................................................................................................ 56 REFERENCES ................................................................................................................. 59 APPENDIX …………………………………………………………………………….. 64 iv LIST OF TABLES Table Page 1.1. Abiotic habitat characteristics of 36 Australian pools with Limnadia present and absent. …………………………………………………………… 10 1.2. Percents of total variation in each parameter explained by outcrop and pool, with remaining variation treated as “residual variation.” …………....…. 12 1.3 Results of individual ANOVAs comparing habitat characteristics in pools with and without Limnadia (Holland and Dingo). ……………………….….. 12 2.1. Abiotic habitat characteristics of seven Australian pools and eight pools from Arizona all containing clam shrimp. …………………………………... 32 3.1 List of successful laboratory hydrations with quantities of Limnadia and Eulimnadia. ………………………………………………………………….. 45 iv LIST OF FIGURES Figure Page 1.1. Illustrations of the diurnal variation in 5 physiochemical parameters of ephemeral pools: (a) Temperature, (b) Conductivity, (c) Dissolved oxygen, (d) pH, and (e) TDS (Total dissolved solids). ….………………….. 8 1.2. Ranges of water temperature, conductivity, dissolved oxygen, pH, and TDS for 36 temporary pools. …………………………………………… 11 1.3. Results of a canonical discriminate analysis on all eight dependent variables using data from Holland and Dingo only. …………………………………… 14 2.1. Densities of major categories of microbial inhabitants of 12 ephemeral pools on 4 granite outcrops in Western Australia. ..……………………….... 27 2.2. Changes in water quality parameters of Australian ephemeral pools over time on four different outcrops. …..…………………………………….. 29 2.3. Bacterial and total microbial density trends over time. …………………...… 30 2.4. Relationship between the density of heterotrophic nanoflagellates (cells/L) and the quantity of clam shrimp ( p=0.0025) and between surface area and the quantity of clam shrimp (p=0.0111). ………………….. 30 3.1. Number of hatching occurrences of Limnadia badia and Eulimnadia dahli incubated at 15°C and 27°C. ………………………………………….. 44 3.2. Theoretical distributions of hatching proportions versus multidimensional environmental profile in (a) populations from a more predictable environment and (b) from a less predictable environment. …......................… 53 v CHAPTER I HABITAT CHARACTERISTICS OF EPHEMERAL ROCK POOLS MAY PREDICT THE DISTRIBUTION OF THE CLAM SHRIMP, LIMNADIA BADIA Introduction The biological and abiotic factors that structure freshwater invertebrate communities and determine the distribution and abundance of their members are variable in time and space and depend on the type of community and the habitat in question. Structuring in communities is generally thought to vary along a continuum from permanent freshwater bodies to temporary freshwater environments (Wellborn et al. 1996, Euliss et al. 2004, Jocqué et al. 2007b). Some work has suggested that predation is the dominant structuring force in the most permanent communities while competition is more powerful in structuring pools that are less permanent, such as temporary ponds that dry at least once per year (Wilbur 1987). However, bodies of water on the most ephemeral edge of the continuum (lasting just days to weeks) seem to host communities that are structured more by environmental conditions than by any biotic interactions (Jocqué et al. 2007a). Increasingly, temporary pools have been used as models to investigate community ecology (Srivastava et al. 2004). Often, several pools can be found in close proximity, with each pool representing a microcosm that operates on a temporal and spatial scale 1 that is small enough to be well suited for field observations. However, if these pool communities are structured mainly on the basis of abiotic characteristics, such as aspects of water chemistry, they may not be suitable for the study of some major concepts in community ecology. Biotic interactions, such as coexistence, competition, and predation, may be observed but they may not be important for the organization of rock pool communities. Multiple varieties of interspecific interactions have been observed in temporary pool branchiopods. Coexistence among large branchiopods is a reasonably common phenomenon (Maeda-Martínez et al. 1997). Anostraca (fairy shrimp), Notostraca (tadpole shrimp), and Spinicaudata (clam shrimp) can regularly be found in the same pools (Dodson 1987, Maeda-Martínez et al. 1997). However, there is also evidence for successional, inter-species presence in Anostraca, in which one species at a time dominates a particular pool (Dumont & Negrea 2002). Whether this temporal separation is a result of competition or some other factor, like pre-existing differences in life cycle, is unknown. Petrov and Cvetković (1997) observed up to four anostracan species coexisting in one pond. Alternatively, pools on and around a granite outcrop in Texas presented a segregation of fairy shrimp species (Belk 1991). These non-overlapping distributions suggest competitive exclusion; however, upon closer inspection the segregating mechanism may have been a life history constraint (Belk 1991). Branchinecta packardi reproduces rapidly enough to inhabit the very shallow pools at the peak of the rock, whereas Streptocephalus texanus reproduces too slowly to be able to maintain viable populations in those pools (Belk 1991). Interspecific interactions among branchiopods manifest in a number of different ways; however, when species are 2 segregated, the reasons seem to be related to life-history factors and habitat constraints, such as those in the above example, rather than direct resource competition. Temporary pool communities are more likely to be structured by abiotic characteristics and dispersal limitation (Jocqué et al. 2007a), especially