Patterns in the Distribution and Abundance of Reef Fishes in South Eastern Australia Madhavi A. Colton Submitted in total fulfilment of the requirements of the degree of Doctor of Philosophy March 2011 Department of Zoology The University of Melbourne Parkville, Victoria 3010 Australia ABSTRACT This research investigated patterns in the distribution and abundance of nearshore fishes of south-eastern Australia. I used two methods to survey fishes, underwater visual census (UVC) and baited remote underwater video (BRUV). A comparison between these methods revealed that BRUV recorded higher relative abundance of mobile predators, while UVC observed higher relative abundance of herbivores, territorial species, and small site-attached species. These results suggest that studies surveying diversity would do best to employ multiple methods. In cases where funds are limited, UVC may provide a more complete estimate of diversity than BRUV as UVC recorded higher diversity, species richness and more individuals. Combining measures of abundance with habitat data, I investigated fish-habitat associations, specifically exploring how altering spatial grain influenced the strength of correlations between fish and habitat. Species of different sizes responded to habitat measured over different scales, with large-bodied species only displaying strong correlations with habitat when it was measured over large scales. These results suggest that research quantifying fish-habitat associations needs to take spatial grain into account. In addition, many species may respond to changes in habitat at scales larger than are typically investigated. Understanding not only how species interact with their environment but also the scale at which these associations occur is essential for management and conservation. I investigated biogeographic patterns in the distribution of fishes in Victoria using abundance measured by BRUV and UVC. The BRUV data displayed a cline in change across the state in which dissimilarities between locations were linearly related to distance. In contrast, data collected using UVC indicated the presence of a large faunal break in the vicinity of Ninety Mile Beach, and a second break between Cape Conran and Cape Howe, suggesting that contemporary habitat discontinuity, flow and/or temperature may be important factors structuring communities in this region. At a still larger scale, I explored relationships at upper and lower bounds between body size, geographic range size and abundance using data collected from Australia and New Zealand. At maxima, the relationship between body size and abundance was i negative but steeper than expected, possibly driven by diver-averse behaviour of large species. At minima, body size and geographic range size were positively related, implying that body size determines the minimum area that a species must occupy. In contrast, at the upper bound this relationship was negative for non-perciform fishes, a K-selected group whose geographic range size could be constrained by their limited dispersal capacity. Distribution-abundance relationships deviated from predictions, with a negative relationship at the upper bound for Perciformes, which could be driven by the high dispersal potential of widespread species that results in diffuse low- density populations. From these results, I concluded, first, that fishes appear to differ from terrestrial taxa, which may be attributed in part to large-bodied fishes’ limited capacity for dispersal. Second, the approach of applying regressions to maxima and minima uncovered relationships that would have been obscured had they been investigated at the mean, highlighting the importance of exploring limits in macroecological relationships. ii DECLARATION This is to certify that i. the thesis comprises only my original work towards the PhD except where indicated in the Preface, ii. due acknowledgement has been made in the text to all other material used, iii. the thesis is less than 100,000 words in length, exclusive of tables, maps, bibliographies and appendices. 7 March, 2011 Madhavi A. Colton Date iii PREFACE Chapter Four is a meta-analysis of data collected by myself, Dr. Sean Connell of the University of Adelaide, and Mr. Alejandro Pérez-Matus of Victoria University in Wellington, New Zealand. I conceived the idea for the chapter, analysed and wrote up the data. Dr. Connell and Mr. Pérez-Matus supplied measures of fish density that were made in the field. iv ACKNOWLEDGEMENTS Thanks are due first and foremost to my supervisor Dr. Stephen Swearer whose advice and support were invaluable. This work would not have been feasible without the field assistance of Mr. Dean Chamberlain, Mr. John Ford, Dr. Christian Jung, Mr. Matthew LeFeuvre and Mr. Malcolm Lindsay. Mr. Michael Sams was immensely helpful in identifying the invertebrates, algae and seagrasses in habitat photos. The Parks Victoria staff at the Mallacoota Office went above and beyond in their support of our research efforts at Gabo Island. Thanks also to the Parks Victoria crew at Wilsons Promontory. This research was funded by Natural Heritage Trust and Parks Victoria, and I was supported by an Australian Postgraduate Award and a Helen McPherson-Smith Scholarship. I was also supported by my husband Zack Kushner who showed incredible patience with me through this process. v TABLE OF CONTENTS General Introduction…………………………………………………………… 1 Literature Cited…………………………………………………………….. 3 Chapter One: A comparison of two survey methods: differences between underwater visual census and baited remote underwater video……………..... 6 Abstract…………………………………………………………….............. 6 Introduction………………………………………………………….……… 7 Materials & Methods……………………………………………………….. 12 Results………………………………………………………………………. 25 Discussion…………………………………………………………............... 30 Conclusion …………………………………………………………………. 40 Literature Cited……………………………………………………………... 40 Chapter Two: Body size and spatial grain influence fish-habitat associations in temperate marine fishes ……………………………………………………… 44 Abstract……………………………………………………………................ 44 Introduction………………………………………………………….……… 44 Materials & Methods………………………………………………………... 48 Results………………………………………………………………………. 54 Discussion…………………………………………………………............... 60 Literature Cited……………………………………………………………... 68 Chapter Three: Locating faunal breaks in the nearshore fish assemblage of Victoria, Australia…...………………………………………………………….. 71 Abstract……………………………………………………………................ 71 Introduction………………………………………………………….……… 71 Materials & Methods……………………………………………………….. 76 Results………………………………………………………………………. 82 Discussion…………………………………………………………............... 87 Literature Cited……………………………………………………………... 96 Chapter Four: Relationships between Geographic Range Size, Body Size and Abundance in Temperate Marine Fishes…………………..…………………. 98 Abstract……………………………………………………………................ 98 Introduction………………………………………………………….……… 99 Materials & Methods……………………………………………………….. 102 Results………………………………………………………………………. 110 Discussion…………………………………………………………............... 112 Conclusion …………………………………………………………………. 124 Literature Cited……………………………………………………………... 125 General Conclusion……………………………………………………………. 129 Literature Cited…………………………………………………………….. 130 vi GENERAL INTRODUCTION Ecology is fundamentally the study of the distribution and abundance of species, and these data are essential to any management or conservation plan. Numerous factors can influence where a species occurs and the densities its populations attain. Results from ecological studies investigating the mechanisms driving abundance and distribution are “inextricably scale-dependent” (Sale 1998). At the scale of 1000s km, for example, the distribution of fishes may be best explained by currents and their associated temperatures (e.g. Figueira & Booth 2010), while at the scale of a single reef, a species’ distribution may be strongly associated with structural complexity (e.g. Leum & Choat 1980, Wiens 1989). To gain a complete understanding of abundance and distribution requires investigating these parameters at multiple scales (Eagle et al. 2001, Meyer & Thuiller 2006, Thogmartin & Knutson 2007, Grober- Dunsmore et al. 2008). In particular, the terrestrial literature indicates that consideration of the scale at which an organism relates to its environment is important (Meyer & Thuiller 2006, Murakami et al. 2008), which is ultimately determined by its body size (Holling 1992). There is considerable evidence in the terrestrial literature, and some in the marine literature, to suggest that body size places an ultimate constraint on density (Mohr 1940, Damuth 1981, Marquet et al. 1990, Cotgreave 1993, McGill 2008) and is positively correlated with geographic range size (Brown 1995). In addition, at least in terrestrial systems, range size and abundance are also frequently related (Brown 1984, Borregaard & Rahbek 2010). More than just body size, however, determines how an organism relates to its environment. Behavioural attributes and life history interact to determine where a species can occur and it population growth. The study of distribution, or range size, is ultimately the study of dispersal and colonization (Myers 1997). Dispersal capacity and colonization success are a function of interactions between species-specific traits, e.g. reproductive mode and body size (e.g. Reaka 1980), and the environment (Marshall et al. 2010). Whether dispersal is a good predictor of range size in the marine environment is a matter of some debate (Jones et al. 2002, Hawkins