Options
Goatley, Christopher
Loading...
Given Name
Christopher
Christopher
Surname
Goatley
UNE Researcher ID
une-id:cgoatley
Email
cgoatley@une.edu.au
Preferred Given Name
Christopher
School/Department
School of Environmental and Rural Science
34 results
Now showing 1 - 10 of 34
- PublicationBiologically mediated sediment fluxes on coral reefs: sediment removal and off-reef transportation by the surgeonfish 'Ctenochaetus striatus'Off-reef sediment transport by the surgeonfish 'Ctenochaetus striatus' (Acanthuridae) was quantified on the reef crest at Lizard Island, Great Barrier Reef. Three independent methods were implemented to estimate sediment ingestion rates. These considered (1) the bite rate and bite volume, (2) the defecation rate and faecal pellet size, and (3) the average gut contents and throughput rate. The 3 methods provided a broad range of estimates of sediment ingestion from 8.8 ± 2.4, to 66.1 ± 14.4 g fish-1 d-1 (mean ± SE). Nevertheless, these estimates were comparable to rates of sediment ingestion by parrotfishes (Labridae), the other major sediment-moving group on reefs. Overall, 36.5% of all sediment ingested was transported from the upper reef crest into deeper water, equating to a removal rate of 28.6 ± 6.2 kg 100 m-2 yr-1 at the study site. By brushing the reef, 'C. striatus' reduces the sediment loading in the epilithic algal matrix (EAM) while causing little damage to the algal turf. Reducing sediments in EAMs provides favourable settlement surfaces for benthic organisms and increases the palatability of the EAM to herbivorous reef fishes, thus supporting reef resilience. The ecological importance of 'C. striatus', which is abundant on reefs throughout the IndoPacific, appears to have been underestimated, particularly when considering reef sediment dynamics.
- PublicationThe role of fishes as food: A functional perspective on predator-prey interactions(Wiley-Blackwell Publishing Ltd, 2021-05)
; Bellwood, David R1. Every animal dies. In nature, mortality usually occurs due to predation by other animals. One of the fundamental consequences of mortality is the transfer of energy and nutrients from one organism (prey) to another (predator). On coral reefs, these key interactions and processes, that are essential for ecosystem functioning, are primarily mediated by fishes; up to 53% of fishes on coral reefs can be regarded as piscivorous.
2. To date, piscivory on coral reefs has been primarily studied with regard to the species piscivores feed on, and how piscivores control populations. Consequently, understanding prey selectivity by piscivorous fishes has been a major goal. However, prey functional traits may also be important in understanding these ‘energy transactions’, especially in complex ecosystems such as coral reefs.
3. Our goal, therefore, was to quantify-at a community level-functional traits of prey that have been shown to influence predator-prey interactions. We found that, on average, deep‐bodied, social fishes occupy higher positions in the water column, whereas solitary species are usually elongate and more closely associated with the benthos. On closer examination, we found that solitary species have a size‐dependent relationship, with substratum associations shifting to water column associations, at approximately 50 mm body length.
4. Our results reveal three distinct prey functional groups: cryptobenthic substratum dwellers, solitary epibenthics and social fishes. These groups display significant differences in their morphologies and behaviours. Furthermore, based on a meta‐analysis of published mortality rates of small‐bodied (<100 mm TL) reef fishes, we show that the three groups display different mortality rates, possibly due to differential exposure to, and potential to be captured by, different predator types.
5. Although fishes are widely available on coral reefs, they may not be equally available as prey to all piscivore types. Prey are not simply victims; they are capable of influencing potential predation through functional traits.
- PublicationFishes on coral reefs: changing roles over the past 240 million yearsKey morphological traits reveal changes in functional morphospace occupation of reef fish assemblages over time. We used measurements of key functional attributes (i.e., lower jaw length and orbit diameter) of 208 fossil fish species from five geological periods to create bivariate plots of functional morphological traits through time. These plots were used to examine possible function and ecological characteristics of fossil reef fish assemblages throughout the Mesozoic and Cenozoic. A previously unknown trend of increasing orbit diameter over time became apparent. The Teleostei are the principal drivers of this change. The Eocene appears to mark a dramatic increase in two previously rare feeding modes in fishes: nocturnal feeding and high-precision benthic feeding. Interestingly, members of the Pycnodontiformes had relatively large eyes since the Triassic and appear to be the ecological precursors of their later teleost counterparts and may have been among the earliest nocturnal feeding fishes. Our results highlight potential changes in the roles of fishes on coral reefs through time.
- PublicationThe Rise of Jaw Protrusion in Spiny-Rayed Fishes Closes the Gap on Elusive Prey(Cell Press, 2015)
; - PublicationLow-quality sediments deter grazing by the parrotfish 'Scarus rivulatus' on inner-shelf reefsElevated sediment loads in the epilithic algal matrix (EAM) deter grazing by herbivorous fishes and may compromise their critical roles on coral reefs. However, the properties of sediments that drive herbivore deterrence are unknown. Binary choice trials in aquaria were used to examine the effects of three sediment attributes-sediment source, grain size and organic load-on grazing by the abundant inner-shelf parrotfish, Scarus rivulatus. Fish were presented with a choice between EAM-covered rocks treated with (a) terrigenous or reefal sediments, (b) fine or coarse sediments or (c) sediments with high or low organic loads. Scarus rivulatus did not show a preference for sediments from different sources (terrigenous vs. reefal); however, a clear preference was evident for fine-grained sediments over coarse (109 % more bites) and sediments with high organic loads over low (147 % more bites). The avoidance of coarse sediments is likely to be a key factor driving the inhibition of grazing on mid-shelf reefs, which are dominated by coarse sediments. In contrast, on innershelf reefs, grazing by parrotfishes may be deterred primarily by high sediment loads, which reduce the proportional organic content in EAM sediments. Our study highlights the potential impact of sediments on critical ecological processes and the threats posed by changing sediment loads on inner-shelf reefs.
- PublicationReef-scale partitioning of cryptobenthic fish assemblages across the Great Barrier Reef, AustraliaOnshore to offshore gradients in marine assemblages have been well documented on coral reefs, with most studies showing a distinct separation between onshore and offshore locations. Here we use enclosed anaesthetic sampling of small, cryptobenthic reef fishes to assess changes in assemblage composition across the Great Barrier Reef continental shelf. The cryptobenthic fishes exhibited fine-scale partitioning across the shelf. Three dominant species of goby accounted for over 55% of all fishes collected, with 1 species characterising each of the 3 key shelf positions: inner-, mid- and outer-shelf. Multivariate analyses of assemblage composition revealed further separation of reefs within the inner- and mid-shelf positions, highlighting the exceptional sensitivity of cryptobenthic reef fish assemblages to shelf position, with a progressive separation of individual reef assemblages with distance from the shore. These among-reef patterns contrast markedly with other reef fish taxa which invariably show 2 broad assemblages across the continental shelf (inner- vs. a composite mid- and outer-shelf community). As a result of this exceptional sensitivity to environmental conditions, cryptobenthic reef fish communities may represent good subjects for high-resolution monitoring of disturbances on coral reefs.
- PublicationClarifying functional roles: algal removal by the surgeonfishes Ctenochaetus striatus and Acanthurus nigrofuscusThe lined bristletooth, Ctenochaetus striatus, and the brown surgeonfish, Acanthurus nigrofuscus, are among the most abundant surgeonfishes on Indo-Pacific coral reefs. Yet, the functional role of these species has been the focus of an ongoing debate lasting at least six decades. Specifically, to what extent are C. striatus herbivorous like the visually similar A. nigrofuscus? To address this question, we used natural feeding surfaces, covered with late successional stage reef-grown algal turfs, to examine turf algal removal by the two species. Surfaces exposed to C. striatus in laboratory experiments exhibited no significant reductions in turf length or area covered by turfing algae. In marked contrast, A. nigrofuscus reduced turf length by 51% and area covered by turfing algae by 15% in 1 h. The gut contents of specimens from the reef revealed that A. nigrofuscus predominantly ingests algae (the dominant item in 79.6–94.7% of gut content quadrats), while C. striatus ingests detritus and sediments (dominant in 99.6–100% of quadrats). Therefore, C. striatus ingests detritus and sediment, leaving mature algal turfs relatively intact, while A. nigrofuscus directly removes and ingests turf algae. The function of C. striatus differs from cropping herbivorous surgeonfishes such as A. nigrofuscus. On coral reefs, C. striatus brush detrital aggregates from algal turfs, removing microorganisms, organic detritus and inorganic sediment. Confusion over the functional role of C. striatus may stem from an inability to fit it into a single functional category.
- PublicationEvolution of long-toothed fishes and the changing nature of fish-benthos interactions on coral reefs(Nature Publishing Group, 2014)
- PublicationA functional evaluation of feeding in the surgeonfish Ctenochaetus striatus: the role of soft tissues(The Royal Society Publishing, 2018-01-31)
; - PublicationSite fidelity and homing in juvenile rabbitfishes (Siganidae)The behaviour of juvenile fishes is critical in establishing the link between recruitment and subsequent adult populations. If juvenile fishes move, they can respond to variation in local conditions before adult home ranges are established. Alternatively, if juveniles establish fixed home ranges at settlement, their decisions may determine future population densities at small spatial scales. Field observations and translocations revealed that juvenile rabbitfishes ('Siganus corallinus' and 'S. doliatus') have small home ranges and strong homing abilities (covering 6 m in 1 h or 36 m within 24 h). Only four of 22 individuals failed to return; all were transferred up-current, suggesting that olfaction is important in homing. Small home ranges and strong homing tendencies in juvenile herbivores suggest that decisions made by recruits will impact the spatial extent of both adult fishes and the functional roles they play within ecosystems.