Showing papers by "James Cook University published in 2004"

Extinction risk from climate change

Abstract: Climate change over the past approximately 30 years has produced numerous shifts in the distributions and abundances of species and has been implicated in one species-level extinction. Using projections of species' distributions for future climate scenarios, we assess extinction risks for sample regions that cover some 20% of the Earth's terrestrial surface. Exploring three approaches in which the estimated probability of extinction shows a power-law relationship with geographical range size, we predict, on the basis of mid-range climate-warming scenarios for 2050, that 15-37% of species in our sample of regions and taxa will be 'committed to extinction'. When the average of the three methods and two dispersal scenarios is taken, minimal climate-warming scenarios produce lower projections of species committed to extinction ( approximately 18%) than mid-range ( approximately 24%) and maximum-change ( approximately 35%) scenarios. These estimates show the importance of rapid implementation of technologies to decrease greenhouse gas emissions and strategies for carbon sequestration.

Confronting the coral reef crisis

Abstract: The worldwide decline of coral reefs calls for an urgent reassessment of current management practices. Confronting large-scale crises requires a major scaling-up of management efforts based on an improved understanding of the ecological processes that underlie reef resilience. Managing for improved resilience, incorporating the role of human activity in shaping ecosystems, provides a basis for coping with uncertainty, future changes and ecological surprises. Here we review the ecological roles of critical functional groups (for both corals and reef fishes) that are fundamental to understanding resilience and avoiding phase shifts from coral dominance to less desirable, degraded ecosystems. We identify striking biogeographic differences in the species richness and composition of functional groups, which highlight the vulnerability of Caribbean reef ecosystems. These findings have profound implications for restoration of degraded reefs, management of fisheries, and the focus on marine protected areas and biodiversity hotspots as priorities for conservation.

Coral decline threatens fish biodiversity in marine reserves.

Abstract: The worldwide decline in coral cover has serious implications for the health of coral reefs. But what is the future of reef fish assemblages? Marine reserves can protect fish from exploitation, but do they protect fish biodiversity in degrading environments? The answer appears to be no, as indicated by our 8-year study in Papua New Guinea. A devastating decline in coral cover caused a parallel decline in fish biodiversity, both in marine reserves and in areas open to fishing. Over 75% of reef fish species declined in abundance, and 50% declined to less than half of their original numbers. The greater the dependence species have on living coral as juvenile recruitment sites, the greater the observed decline in abundance. Several rare coral-specialists became locally extinct. We suggest that fish biodiversity is threatened wherever permanent reef degradation occurs and warn that marine reserves will not always be sufficient to ensure their survival.

Flexibility in algal endosymbioses shapes growth in reef corals

Abstract: The relation between corals and their algal endosymbionts has been a key to the success of scleractinian (stony) corals as modern reef-builders, but little is known about early stages in the establishment of the symbiosis. Here, we show that initial uptake of zooxanthellae by juvenile corals during natural infection is nonspecific (a potentially adaptive trait); the association is flexible and characterized by a change in (dominant) zooxanthella strains over time; and growth rates of experimentally infected coral holobionts are partly contingent on the zooxanthella strain harbored, with clade C-infected juveniles growing two to three times as fast as those infected with clade D.

Habitat loss, resource specialization, and extinction on coral reefs

Abstract: Coral reefs worldwide are being degraded due to global warming (coral bleaching) and coastal development (sedimentation and eutrophication). Predicting the risk of species extinctions from this type of habitat degradation is one of the most challenging and urgent tasks facing ecologists. Habitat specialists are thought to be more prone to extinction than generalists; however specialists may be more susceptible to extinction because, 1) they are specialists per se, 2) because they are less abundant than generalists, or 3) both. Here I show that declines in coral abundance lead to corresponding declines in the abundance of coral-dwelling fishes, but with proportionally greater losses to specialists than generalists. In addition, specialists have smaller initial population sizes than generalists. Consequently, specialists face a dual risk of extinction because their already small populations decline more rapidly than those of generalists. Corresponding with this increased extinction risk, I describe the local extinction of one specialist species and the near-global extinction of another species. I conclude that habitat specialists will be the first species lost from coral reefs because their small populations suffer the most from human-induced disturbances.

Recognition and selection of settlement substrata determine post-settlement survival in corals

Abstract: Habitat recognition and selective settlement by dispersive propagules greatly increases the post-settlement survival chances of sessile organisms. To better understand the key role some species can play in the structure of highly complex coral reef ecosystems, we compare the role of two independent, but sequential, processes: settlement choice and post-settlement survival. This study describes the chemical and physical recognition and ranking of specific settlement substrata by coral larvae. Several species of crustose coralline algae (CCA) are known to induce coral settlement; however they also employ physical and biological anti-settlement defense strategies that vary greatly in effectiveness. We examine the interactions between settling larvae of two common reef building coral species (Acropora tenuis and A. millepora) and five species of CCA (Neogoniolithon fosliei, Porolithon onkodes, Hydrolithon reinboldii, Titanoderma prototypum, and Lithoporella melobesioides) that co-occur on reef crests and slopes of the Great Barrier Reef, Australia. Distinct settlement patterns were observed when coral larvae were provided with a choice of settlement substrata. Settlement on the most preferred substratum, the CCA species T. prototypum, was 15 times higher than on N. fosliei, the least preferred substratum. The rates of post-settlement survival of the corals also varied between CCA species in response to their anti-settlement strategies (shedding of surface cell layers, overgrowth, and potential chemical deterrents). Rates of larval settlement, post-settlement survival, and the sensitivity of larvae to chemical extracts of CCA were all positively correlated across the five species of CCA. Nonliving settlement substrata on coral reefs is sparse; consequently the fact that only a few CCA species (notably T. prototypum) facilitate coral recruitment, has important implications for structuring the reef ecosystem.

Marine reserve benefits local fisheries

Abstract: The utility of no-take marine reserves as fisheries-management tools is controversial. It is hypothesized that marine reserves will help to sustain fisheries external to them by becoming net exporters of adults (the “spillover effect”) and net exporters of propagules (the “recruitment effect”). Local fishery benefits from spillover will likely generate support from fishing communities for marine reserves. We used underwater visual census to show that biomass of Acanthuridae (surgeonfish) and Carangidae (jacks), two families of reef fish that account for 40–75% of the fishery yield from Apo Island, Philippines, tripled in a well-protected no-take reserve over 18 years (1983–2001). Biomass of these families did not change significantly over the same period at a site open to fishing. The reserve protected 10% of the total reef fishing area at the island. Outside the reserve, biomass of these families increased significantly closer to (200–250 m) than farther away from (250–500 m) the reserve boundary over time. We used published estimates of fishery catch and effort, and fisher interviews (creel surveys) to show that the total catch of Carangidae and Acanthuridae combined at Apo Island was significantly higher after (1985–2001) than before (1981) reserve establishment. Hook-and-line catch per unit effort (CPUE) at the island was 50% higher during 1998–2001 (reserve protected 16–19 years) than during 1981–1986 (pre-reserve and early phases of reserve protection). Total hook-and-line effort declined by 46% between 1986 and 1998–2001. Hook-and-line CPUE of Acanthuridae was significantly higher close to (within 200 m) than far from the reserve. CPUE of Carangidae was significantly higher away from the reserve, possibly reflecting a local oceanographic effect. The benefits of the reserve to local fisheries at the island were higher catch, increased catch rate, and a reduction in fishing effort. The fishery and tourism benefits generated by the reserve have enhanced the living standard of the fishing community.

kingroup: a program for pedigree relationship reconstruction and kin group assignments using genetic markers

Abstract: kingroup is an open source java program implementing a maximum likelihood approach to pedigree relationships reconstruction and kin group assignment. kingroup implements a new method (currently being performance tested) for reconstructing groups of kin that share a common relationship by estimating an overall likelihood for alternative partitions. A number of features found in kinship (Goodnight & Queller 1999) have also been implemented to make them available outside the Classic Macintosh OS platform for the first time.

Effect of season and temperature on mortality in amphibians due to chytridiomycosis

Abstract: Objective To investigate the distribution and incidence of chytridiomycosis in eastern Australian frogs and to examine the effects of temperature on this disease. Design A pathological survey and a transmission experiment were conducted. Procedure Diagnostic pathology examinations were performed on free-living and captive, ill and dead amphibians collected opportunistically from eastern Australia between October 1993 and December 2000. We conducted a transmission experiment in the laboratory to investigate the effects of temperature: eight great barred frogs (Mixophyes fasciolatus) exposed to zoospores of Batrachochytrium dendrobatidis and six unexposed frogs were housed individually in each of three rooms held at 17°C, 23°C and 27°C. Results Chytridiomycosis was the cause of death or morbidity for 133 (55.2%) of 241 free-living amphibians and for 66 (58.4%) of 113 captive amphibians. This disease occurred in 34 amphibian species, was widespread around the eastern seaboard of Australia and affected amphibians in a variety of habitats at high and low altitudes on or between the Great Dividing Range and the coast. The incidence of chytridiomycosis was higher in winter, with 53% of wild frogs from Queensland and New South Wales dying in July and August. Other diseases were much less common and were detected mostly in spring and summer. In experimental infections, lower temperatures enhanced the pathogenicity of B dendrobatidis in M fasciolatus. All 16 frogs exposed to B dendrobatidis at 17°C and 23°C died, whereas 4 of 8 frogs exposed at 27°C survived. However, the time until death for the frogs that died at 27°C was shorter than at the lower temperatures. Infections in survivors were eliminated by 98 days. Conclusion Chytridiomycosis is a major cause of mortality in free-living and captive amphibians in Australia and mortality rate increases at lower temperatures.

Does inbreeding and loss of genetic diversity decrease disease resistance

Abstract: Inbreeding and loss of genetic diversity are predicted to decrease the resistance of species to disease. However, this issue is controversial and there is limited rigorous scientific evidence available. To test whether inbreeding and loss of genetic diversity affect a host''s resistance to disease, Drosophila melanogasterpopulations with different levels of inbreeding and genetic diversity were exposed separately to (a) thuringiensin, an insecticidal toxin produced by some strains of Bacillus thuringiensis, and (b) live Serratia marcescensbacteria. Inbreeding and loss of genetic diversity significantly reduced resistance of D. melanogasterto both the thuringiensin toxin and live Serratia marcescens. For both, the best fitting relationships between resistance and inbreeding were curvilinear. As expected, there was wide variation among replicate inbred populations in disease resistance. Lowered resistances to both the toxin and the pathogen in inbred populations were due to specific resistance alleles, rather than generalized inbreeding effects, as correlations between resistance and population fitness were low or negative. Wildlife managers should strive to minimise inbreeding and loss of genetic diversity within threatened populations and to minimise exposure of inbred populations to disease.

Endemic Infection of the Amphibian Chytrid Fungus in a Frog Community Post-Decline

Abstract: The chytrid fungus Batrachochytrium dendrobatidis has been implicated in the decline and extinction of numerous frog species worldwide. In Queensland, Australia, it has been proposed as the cause of the decline or apparent extinction of at least 14 high-elevation rainforest frog species. One of these, Taudactylus eungellensis, disappeared from rainforest streams in Eungella National Park in 1985–1986, but a few remnant populations were subsequently discovered. Here, we report the analysis of B. dendrobatidis infections in toe tips of T. eungellensis and sympatric species collected in a mark-recapture study between 1994 and 1998. This longitudinal study of the fungus in individually marked frogs sheds new light on the effect of this threatening infectious process in field, as distinct from laboratory, conditions. We found a seasonal peak of infection in the cooler months, with no evidence of interannual variation. The overall prevalence of infection was 18% in T. eungellensis and 28% in Litoria wilcoxii/jungguy, a sympatric frog that appeared not to decline in 1985–1986. No infection was found in any of the other sympatric species. Most importantly, we found no consistent evidence of lower survival in T. eungellensis that were infected at the time of first capture, compared with uninfected individuals. These results refute the hypothesis that remnant populations of T. eungellensis recovered after a B. dendrobatidis epidemic because the pathogen had disappeared. They show that populations of T. eungellensis now persist with stable, endemic infections of B. dendrobatidis.

A record of Late Pleistocene and Holocene carbon accumulation and climate change from an equatorial peat bog (Kalimantan, Indonesia): implications for past, present and future carbon dynamics

Abstract: A 9.5 m core from an inland peatland in Kalimantan, Indonesia, reveals organic matter accumulation started around 26 000 cal. yr BP, providing the oldest reported initiation date for lowland ombrotrophic peat formation in SE Asia. The core shows clear evidence for differential rates of peat formation and carbon storage. A short period of initial accumulation is followed by a slow rate during the LGM, with fastest accumulation during the Holocene. Between ∼13 000 and 8000 cal. yr BP, > 450 cm of peat were deposited, with highest rates of peat (> 2 mm yr−1) and carbon (> 90 g C m−2 yr−1) accumulation between 9530 and 8590 cal. yr BP. These data suggest that Kalimantan peatlands acted as a large sink of atmospheric CO2 at this time. Slower rates of peat (0.15–0.38 mm yr−1) and carbon (7.4–24.0 g C m−2 yr−1) accumulation between ∼8000 and 500 cal. yr BP coincide with rapid peat formation in coastal locations elsewhere in SE Asia. The average LORCA (long-term apparent carbon accumulation rate) for the 9.5 m core is 56 g C m−2 yr−1. These data suggest that studies of global carbon sources, sinks and their dynamics need to include information on the past and present sizeable peat deposits of the tropics. Copyright © 2004 John Wiley & Sons, Ltd.

Marine reserves: long-term protection is required for full recovery of predatory fish populations

Abstract: No-take marine reserves are advocated widely as a potential solution to the loss of marine biodiversity and ecosystem structure, and to over-fishing. We assess the duration of protection required for unfished populations of large predatory reef fish to attain natural states. We have monitored two marine reserves at Sumilon and Apo Islands, Philippines, regularly for 17 years (1983–2000). The biomass of large predatory fish was still increasing exponentially after 9 and 18 years of protection at Sumilon and Apo reserves, respectively. There was little evidence that the rate of accumulation of biomass inside the reserves was slowing down even after so many years of protection. This suggests that the length of time to full recovery will be considerable. We made two assumptions in order to estimate this period. Firstly, that biomass growth will follow the logistic model. Secondly, the conservative assumption that biomass had already attained 90% of the local carrying capacity of the environments in the reserves. We conclude that the time required for full recovery will be 15 and 40 years at Sumilon and Apo reserves, respectively. Such durations of recovery appear consistent with known life history characteristics of these fish, and with empirical data on recovery rates of heavily exploited fish stocks. By the time the full fisheries or ecosystem benefits from such reserves are apparent, human populations and impacts will have doubled in much of the developing world. Thus, networks of such reserves need to be implemented immediately. Furthermore, the management mechanisms for the reserves need to be successful over timescales of human generations.

Differential effects of habitat complexity, predators and competitors on abundance of juvenile and adult coral reef fishes

Abstract: Greater structural complexity is often associated with greater abundance and diversity, perhaps because high complexity habitats reduce predation and competition. Using 16 spatially isolated live-coral reefs in the Bahamas, I examined how abundance of juvenile (recruit) and adult (non-recruit) fishes was affected by two factors: (1) structural habitat complexity and (2) the presence of predators and interference competitors. Manipulating the abundance of low and high complexity corals created two levels of habitat complexity, which was cross-factored with the presence or absence of resident predators (sea basses and moray eels) plus interference competitors (territorial damselfishes). Over 60 days, predators and competitors greatly reduced recruit abundance regardless of habitat complexity, but did not affect adult abundance. In contrast, increased habitat complexity had a strong positive effect on adult abundance and a weak positive effect on recruit abundance. Differential responses of recruits and adults may be related to the differential effects of habitat complexity on their primary predators. Sedentary recruits are likely most preyed upon by small resident predators that ambush prey, while larger adult fishes that forage widely and use reefs primarily for shelter are likely most preyed upon by large transient predators that chase prey. Increased habitat complexity may have inhibited foraging by transient predators but not resident predators. Results demonstrate the importance of habitat complexity to community dynamics, which is of concern given the accelerated degradation of habitats worldwide.

Does increased habitat complexity reduce predation and competition in coral reef fish assemblages

Abstract: Greater habitat complexity is often associated with a greater abundance and diversity of organisms. High complexity habitats may reduce predation and competition, thereby allowing more individuals to occupy a given area. Using 16 spatially isolated reefs in the Bahamas, I tested whether increased habitat complexity reduced the negative effects of resident predators and competitors on recruitment and survival of a common damselfish. Two levels of habitat complexity were cross-factored with the presence or absence of two guilds of resident fishes: predators (sea basses and moray eels) and interference competitors (large territorial damselfishes). I monitored subsequent recruitment and recruit mortality for 60 days. Residents had strong negative effects on recruitment regardless of habitat complexity. In the presence of residents, recruits suffered high mortality immediately after settlement that was similar on low and high complexity reefs, although high complexity reduced mortality of recruits that survived this early postsettlement period. Comparisons between shelter hole diameters and the sizes of residents suggest that territorial damselfishes and small resident predators could access most shelter holes, whereas large resident predators were excluded from many shelter holes. This study demonstrates that whether habitat complexity reduces predation and competition may depend on several key factors, such as the availability of appropriate shelter, behavioral attributes of interactors, and developmental stage of prey/inferior competitors.

A Functional morphospace for the skull of labrid fishes: patterns of diversity in a complex biomechanical system

Abstract: The Labridae (including wrasses, the Odacidae and the Scaridae) is a species-rich group of perciform fishes whose members are prominent inhabitants of warm-temperate and tropical reefs worldwide. We analyse functionally relevant morphometrics for the feeding apparatus of 130 labrid species found on the Great Barrier Reef and use these data to explore the morphological and mechanical basis of trophic diversity found in this assemblage. Morphological measurements were made that characterize the functional and mechanical properties of the oral jaws that are used in prey capture and handling, the hyoid apparatus that is used in expanding the buccal cavity during suction feeding, and the pharyngeal jaw apparatus that is used in breaking through the defences of shelled prey, winnowing edible matter from sand and other debris, and pulverizing the algae, detritus and rock mixture eaten by scarids (parrotfishes). A Principal Components Analysis on the correlation matrix of a reduced set of ten variables revealed complete separation of scarids from wrasses on the basis of the former having a small mouth with limited jaw protrusion, high mechanical advantage in jaw closing, and a small sternohyoideus muscle and high kinematic transmission in the hyoid four-bar linkage. Some scarids also exhibit a novel four-bar linkage conformation in the oral jaw apparatus. Within wrasses a striking lack of strong associations was found among the mechanical elements of the feeding apparatus. These weak associations resulted in a highly diverse system in which functional properties occur in many different combinations and reflect variation in feeding ecology. Among putatively monophyletic groups of labrids, the cheilines showed the highest functional diversity and scarids were moderately diverse, in spite of their reputation for being trophically monomorphic and specialized. We hypothesize that the functional and ecological diversity of labrids is due in part to a history of decoupled evolution of major components of the feeding system (i.e. oral jaws, hyoid and pharyngeal jaw apparatus) as well as among the muscular and skeletal elements of each component.

Temporal stability of the Eating Disorder Examination Questionnaire.

Abstract: Objectives The current study examined the stability and internal consistency of the Eating Disorder Examination Questionnaire (EDE-Q) in a general population sample. Methods The EDE-Q was administered to a community sample of women aged 18-45 on two occasions, with a median test-retest interval of 315.0 days. Results Pearson correlations between items of the EDE-Q assessing attitudinal features of eating disorder psychopathology ranged from 0.57 for the Restraint subscale to 0.77 for the Eating Concern subscale. The stability of items addressing eating disorder behaviors was much lower, with phi coefficients for the occurrence of objective bulimic episodes, subjective bulimic episodes, and use of exercise as a compensatory behavior of 0.44, 0.24, and 0.31, respectively, and Kendall's tau b correlations of 0.44, 0.28, and 0.31, respectively, for the frequency of these behaviors, across occasions. The internal consistency of the EDE-Q was high, with a Cronbach alpha coefficient for the global scale of 0.93, compared with a value of 0.90 for the Eating Disorder Examination interview. Discussion Items of the EDE-Q assessing attitudinal features of eating disorder psychopathology demonstrate a high degree of temporal stability, whereas the stability of items addressing eating disorder behaviors is much lower. In the case of compensatory eating disorder behaviors, low stability is likely to reflect actual trait variation, whereas the low stability of binge eating behaviors, in particular subjective bulimic episodes, is likely to reflect both trait variation and measurement error. The high internal consistency of EDE-Q items supports its use as a screening instrument in two-phase epidemiologic studies.

A method for calculating effective bulk composition modification due to crystal fractionation in garnet‐bearing schist: implications for isopleth thermobarometry

Abstract: Quantitative P–T path determination in metamorphic rocks is commonly based on the variation in composition of growth-zoned garnet However, some component of growth zoning in garnet is necessarily the result of an effective bulk composition change within the rock that has been generated by crystal fractionation of components into the core of garnet Therefore, any quantitative calculation of the P–T regime of garnet growth should be completed using an accurate assessment of the composition of the chemical system from which garnet is growing Consequently, a method for calculating the extent of crystal fractionation that provides a means of estimating the composition of the unfractionated rock at any stage during garnet growth is developed The method presented here applies a Rayleigh fractionation model based on measured Mn content of garnet to generate composition v modal proportion curves for garnet, and uses those curves to estimate the vectors of crystal fractionation The technique is tested by calculating the precision of the equilibrium between three garnet compositional variables within the chemical system determined to be appropriate for each of a series of microprobe analyses from garnet Application of the fractionation calculations in conjunction with the P–T estimates based on intersecting compositional isopleths provides a means of calculating P–T conditions of garnet growth that is based on individual point-analyses on a garnet grain Such spatially precise and easily obtainable P–T data allow for detailed parallel studies of the microstructural, the P–T, and the chemical evolution of metamorphosed pelites This method provides a means of studying the dynamics of orogenic systems at a resolution that was previously unattainable

Tree domestication in tropical agroforestry

Abstract: We execute tree ‘domestication’ as a farmer-driven and market-led process, which matches the intraspecific diversity of locally important trees to the needs of subsistence farmers, product markets, and agricultural environments. We propose that the products of such domesticated trees are called Agroforestry Tree Products (AFTPs) to distinguish them from the extractive tree resources commonly referred to as non-timber forest products (NTFPs). The steps of such a domestication process are: selection of priority species based on their expected products or services; definition of an appropriate domestication strategy considering the farmer-, market-, and landscape needs; sourcing, documentation and deployment of germplasm (seed, seedlings or clonal material); and tree improvement research (tree breeding or cultivar selection pathways). The research phase may involve research institutions on their own or in participatory mode with the stakeholders such as farmers or communities. Working directly with the end-users is advantageous towards economic, social and environmental goals, especially in developing countries. Two case studies (Prunus africana and Dacryodes edulis) are presented to highlight the approaches used for medicinal and fruit-producing species. Issues for future development include the expansion of the program to a wider range of species and their products and the strengthening of the links between product commercialization and domestication. It is important to involve the food industry in this process, while protecting the intellectual property rights of farmers to their germplasm.

Osteoprotegerin and Osteopontin Are Expressed at High Concentrations Within Symptomatic Carotid Atherosclerosis

Abstract: Background and Purpose— The aim of this study was to compare the concentration of osteoprotegerin (OPG), receptor activator of nuclear factor κB ligand (RANKL), and osteopontin (OPN) in stable (asymptomatic) and unstable (symptomatic) carotid atherosclerosis. In addition, we were interested in the effect of angiotensin II blockade on the secretion of these proteins by unstable atherosclerosis. Methods— Endarterectomy samples removed from patients with recent (within 6 weeks) or no previous focal neurological symptoms were assessed by immunohistochemistry, Western analysis, and explant culture. Concentrations of OPG, RANKL, and OPN were measured by mean optical density (MOD), densitometry of protein bands, and enzyme-linked immunosorbent assay of supernatants from explant culture, and compared between symptomatic and asymptomatic patients. Results— The concentration of OPG and OPN within the proximal internal carotid (PIC) part of the endarterectomy specimen removed from symptomatic patients was elevated 2...

The generic skills debate in research higher degrees

Abstract: Generic or transferable skills as outcomes of research higher degrees have been the subject of considerable development and debate in universities in recent times. The development of generic skills has been motivated by the belief that there are skills which all graduates should possess, and which would be applicable to a wide range of tasks and contexts beyond the university setting. This paper reviews these developments and debates drawing on a literature from the USA, the UK, with particular reference to Australia. It cites examples of generic skills programs and considers evidence of students' responses to them. Reviewing criticisms which have been levelled at the idea of generic skills in research higher degrees, the discussion identifies a number of questions which need to be addressed if this development is to succeed.

Modeling the Role of Sodic Alteration in the Genesis of Iron Oxide-Copper-Gold Deposits, Eastern Mount Isa Block, Australia

Abstract: Liberation of iron and potassium by widespread postmetamorphic albitization of country rocks was one of the likely contributing processes in the formation of both barren and mineralized magnetite ± chalcopyrite + biotite + gold + hematite + clinopyroxene + actinolite + apatite ironstones in the Cloncurry district of the Proterozoic Mount Isa block. Whole-rock geochemical data indicate nearly immobile Al, Ga, ±Ti, Zr during transformation of a variety of least altered rocks toward albitite. The data indicate that the addition of Na from a brine to the rock accompanied the loss of Fe, K, Ba, Rb ± Ca, Sr, Co, V, Mn, Pb, and Zn from those altered rocks and enrichment in the brine, but that Cu was not systematically stripped from a variety of wall rocks during albitization. Conversely, the formation of metasomatic ironstones, the immediate hosts to some Cu-Au ores, involves addition of most of the same elements that were lost during albitization. The correlation between intensity of alteration, its distribution and timing (e.g., in breccias cored by ca. 1530–1500 Ma granitoids), and convergence of all rock types toward magmatic stable isotope values provides strong evidence for a substantial component of igneous-derived fluid. Simulations of the albitization process were carried out isothermally at 550°C and 350 MPa and polythermally from these conditions down to 400°C and 200 MPa, using the Gibbs minimization method with HCh software and the UNITHERM database. Both simple fluid-rock mixing models and more complicated reactor-style algorithms used a range of input fluids (from fluids equilibrated fluid with two-feldspar granite through to Na/K ratios consistent with fluid inclusion results) and geochemical data for initially unaltered wall rocks. The apparent paradox of widespread albitization resulting from fluid released by two-feldspar granites can be explained by relatively small shifts away from the K-feldspar-albite equilibrium curve, and even isothermal model fluids derived from two-feldspar granites produce albitites in calc-silicate rocks outboard of granite-proximal K-feldspar-clinopyroxene skarns, matching field patterns. Those models with fluid Na/K ratios similar to those of fluid inclusions produced the most realistic alteration assemblages, dominated by albite, for both isothermal conditions and decreasing temperature, which approximate those observed in the field. PIXE and microthermometric data on fluid inclusions from quartz in two-feldspar quartz monzonite and pegmatite at the top of the Mount Angelay pluton indicate bulk Na/K molar ratios in the fluid of between 10 and 20, considerably higher than our thermodynamically calculated values for fluid in equilibrium with two-feldspar granite of around 3 (at 550°C, 350 MPa). Such shifts may have been attained by admixture of magmatic-hydrothermal fluid with small amounts of NaCl brines trapped along grain boundaries in scapolite-bearing calc-silicate wall rocks, by fluid immiscibility due to high initial CO2 contents in the felsic intrusions, by contributions from mafic magmas, or from dissolution of salt-rich layers into the intrusions prior to crystallization and fluid release. With increasing amounts of fluid-rock interaction in the models, the fluids were enriched in K, Fe, and Ca, approaching compositions observed in fluid inclusions in the ore deposits. These fluids, reacted with pelitic rocks (which are common ore hosts), would produce magnetite-clinopyroxene ± biotite-actinolite alteration at high temperature, similar to the proximal alteration around ore deposits. We infer that precipitation of sulfides in the Cu-Au deposits was the result of mixing of Cu-bearing brine, of ultimately magmatic origin, but modified extensively via albitization, with sulfur-bearing fluids or reaction of the brine with sulfur-bearing rocks. When Cu was absent from the initial magmatic fluid, barren ironstones may have been the result.