Showing papers by "James Cook University published in 1990"

Identity authentication based on keystroke latencies

Abstract: The variables that help make a handwritten signature a unique human identifier also provide a unique digital signature in the form of a stream of latency periods between keystrokes. This article describes a method of verifying the identity of a user based on such a digital signature, and reports results from trial usage of the system.

A functional analysis of grazing in parrotfishes (family Scaridae): the ecological implications

Abstract: The assumption that parrotfishes represent a single group of grazing herbivores is addressed by morphological, functional and ecological analyses This assumption is rejected The 24 scarine parrotfishes from the Great Barrier Reef, Australia, are divided into two functional groups: excavators and scrapers The osteology and myology of the jaws of all 24 species were examined, and a detailed description of a representative species from each group is provided The relative weights of the major jaw structures of five representative species were quantified Morphological differences between species were interpreted in a functional context and were assessed based on observations of feeding in the field Species in the two functional groups show major group-related differences in their bite speeds, microhabitat utilization patterns, and form and extent of substratum excavation during grazing Group-related differences are also apparent in feeding rates, foray sizes and bite rates The division of the species into two functional groups is supported by both morphological and behavioural observations The ecological significance of two functional groups within the family is discussed in relation to the role of parrotfishes on reefs, particularly in terms of bioerosion

A highly specific and sensitive monoclonal antibody-based ELISA for the detection of circulating antigen in bancroftian filariasis

Abstract: A monoclonal antibody, Og4C3, directed against antigens of Onchocerca gibsoni (but not phosphorylcholine) has been used in a sandwich ELISA to detect a circulating antigen of Wuchereria bancrofti in human serum. The interfering effect of host antibody was reduced by first boiling one part of serum for 5 min in the presence of three parts of 0.1 M Na2EDTA, pH 4.0. A total of 119 sera from individuals and 8 pooled sera from clinically and/or parasitologically defined cases of filariasis, plus 8 individual and 1 pooled endemic control sera, all from the filariasis serum bank of the World Health Organisation, as well as 20 non-endemic control sera, were screened with the assay. Circulating antigen was detected in serum from people infected with W. bancrofti but not Brugia malayi. B. timori, O. volvulus or Loa loa, and not in endemic or non-endemic controls. Of the 68 sera from W. bancrofti-infected subjects, 55/55 parasitologically confirmed and 12/13 clinically confirmed but amicrofilaraemic cases reacted in the assay. A weak but significant correlation (r2 = 0.4016) was found between numbers of microfilariae in blood and detectable levels of circulating antigen from patients with bancroftian filariasis.

Effect of noncompetitive blockade of N-methyl-D-aspartate receptors on the neurochemical sequelae of experimental brain injury.

Abstract: Pharmacological inhibition of excitatory neurotransmission attenuates cell death in models of global and focal ischemia and hypoglycemia, and improves neurological outcome after experimental spinal cord injury. The present study examined the effects of the noncompetitive N-methyl-d-aspartate receptor blocker MK-801 on neurochemical sequelae following experimental fluid-percussion brain injury in the rat. Fifteen minutes after fluid-percussion brain injury (2.8 atmospheres), animals received either MK-801 (1 mg/ kg, i.v.) or saline. MK-801 treatment significantly attenuated the development of focal brain edema at the site of injury 48 h after brain injury, significantly reduced the increase in tissue sodium, and prevented the localized decline in total tissue magnesium that was observed in injured tissue of saline-treated animals. Using phosphorus nuclear magnetic resonance spectroscopy, we also observed that MK-801 treatment improved brain metabolic status and promoted a significant recovery of intracellular free magnesium concentrations that fell precipitously after brain injury. These results suggest that excitatory amino acid neurotransmitters may be involved in the pathophysiological sequelae of traumatic brain injury and that noncompetitive N-methyl-d-aspartate receptor antagonists may effectively attenuate some of the potentially deleterious neurochemical sequelae of brain injury.

Differential predation on mangrove propagules in open and closed canopy forest habitats

Abstract: Amounts of seed predation by grapsid crabs (Brachyura: Grapsidae) on two species of mangroves (Aegiceras corniculatum and Avicennia marina) were compared among different habitats in an Australian mangrove forest. For Avicennia, comparisons were between canopy gaps and the adjacent forest understory for six, mid intertidal, gaps of different sizes. For Aegiceras the comparisons were among canopy gaps in the high intertidal; open, accreting mud/sand banks where mangroves were colonizing in the low intertidal; and in the forest understory in both the high and low intertidal zones. These were repeated in the high salinity (35%0) downstream portion and the low salinity (0-5%0) upstream portion of a tidal river. Predation on A vicennia was significantly higher in the understory than in adjacent canopy gaps. Within a canopy opening, predation was greatest in the smallest gaps and lowest in the largest gaps. Predation on Aegiceras was greater in the high intertidal compared to the low intertidal, but no differences were found between river mouth and upstream locations. In the high intertidal zone of the forest, there were no differences in predation between canopy gap or forest understory sites for Aegiceras. In the low intertidal zone, however, significant differences in amount of predation were found between habitats. More Aegiceras propagules were consumed in the understory than on adjacent accreting sandbanks. Frequency of tidal inundation, which in turn affects the amount of time available to forage, is hypothesized to account for differences in predation between low and high intertidal forests and between small and large canopy gaps. Our results also suggest that 'shade intolerance' in these two species may actually reflect an escape from predators, successful when the seeds are dispersed into open areas such as canopy gaps or mud banks.

Direct tracking of coral larvae: Implications for dispersal studies of planktonic larvae in topographically complex environments

Abstract: The larvae of broadcast spawning corals form visible surface aggregations following the annual spring mass spawning on the Great Barrier Reef. Aerial surveys revealed that these aggregations had patchy distributions which were related to local hydrodynamic features. Aggregations were observed along fronts associated with buoyancy differences between water masses, with boundary mixing at reef surfaces, and with island wakes. Secondary currents associated with these fronts accumulated the buoyant larvae into linear slicks. Fronts may be found in proximity to islands, reefs and coastal headlands. Hence, local topography may determine where larval aggregations occur as well as the fine-scale structure of these patches. Once aggregated into coral spawn slicks, larvae were advected away from reefs in complex, inter-reefal currents. Wind patterns determined the general direction of larval transport and overall degree of larval patchiness. These findings have important implications for modelling studies ...

Shelf-wide erosion, deposition, and suspended sediment tranport during Cyclone Winifred, central Great Barrier Reef, Australia

Abstract: Observation of shelf sediments collected immediately before and after Cyclone Winifred crossed the central Great Barrier Reef shelf (1 February 1986) confirmed that the storm produced a normally graded, mixed terrigenous-carbonate storm layer extending 30 km offshore in water up to 43 m deep. Distinct post-Winifred changes in the cross-shelf distribution of organic carbon and carbonate in the mud-fraction of the sediment suggest that suspended sediment transport was extensive and that the storm layer had multiple sediment sources. On a shelf-wide scale, the storm layer is composed almost entirely of reworked shelf sediment. Erosion depths were greater on the mid-shelf (20-40 m water depth) than on the inner shelf( 6.9 cm and 5.1 cm, respectively. Particles finer than medium sand were eroded and transported out of the mid-shelf. The inner-shelf portion of the storm layer formed by the combination of three sediment sources, including 1) seaward transport of terrigenous sediment in buoyant freshwater flood plumes, 2) resuspension and settling of inner-shelf sediment, and 3) resuspension and shoreward transport of mid-shelf sediment. Mass-balance calculations predict that at least 10-30% of the inner-shelf storm layer is composed of mid-shelf mud. Combined wave and wind-forced currents probably resuspended mid-shelf material and drove the suspended fraction alongshelf and shoreward a minimum distance of 15 km. The results suggest that tropical cyclones are capable of sporadic but efficient cross-shelf transport of suspended sediment. On shallow cyclone-prone shelves, suspended sediment may easily be exchanged between adjacent sedimentary facies. In ancient shelf sequences, the transport history of the mud will be complex, and stratigraphically equivalent facies may have similar mud types but completely different sands.

Epitope Analysis of the Envelope and Non-structural Glycoproteins of Murray Valley Encephalitis Virus

Abstract: Previous studies have shown that antibodies produced against strategic flavivirus epitopes play an important role in recovery and immunity. Definition of the conformation and location of these epitopes and the degree of their conservation among flaviviruses is important to understanding the humoral response to flavivirus infection. In this study we have examined epitopes recognized by 14 monoclonal antibodies (MAbs) produced to the envelope (E) and non-structural (NS1) proteins of Murray Valley encephalitis virus (MVE). These antibodies were analysed for specificity, neutralization, haemagglutination inhibition (HI) and competitive binding. We have identified six distinct epitopes on the E protein which are located in four non-overlapping domains. MAbs to epitopes in one domain neutralized virus, were specific for MVE and Japanese encephalitis virus, and reacted with epitopes resistant to reduction. Two other E domains, one specific to MVE and the other shared by all flaviviruses, also contained neutralization sites and were stabilized by disulphide bonds. The fourth domain on E was conserved among the flaviviruses, sensitive to SDS denaturation and did not induce neutralizing antibody. Studies with MVE NS1 MAbs revealed that they were mostly type-specific, unreactive with conserved epitopes, and unreactive in HI and neutralization tests. The six epitopes identified on NS1 did not overlap and represent antigenic domains either resistant or sensitive to reduction. Immunoblotting of viral proteins in MVE-infected C6/36 cells revealed two distinct forms of NS1 and high Mr proteins of 97K and 108K that represented disulphide-linked heterodimers of E and NS1.

Seed predation by insects in tropical mangrove forests: extent and effects on seed viability and the growth of seedlings

Abstract: Although insects are known to be important seed predators in most terrestrial forests, their role in marine tidal (mangrove) forests has not been examined. Surveys at 12 sites in tropical Australia showed that between 3.1 and 92.7 percent of the seeds or propagules of 12 mangrove tree species had been attacked by insects. Seeds/propagules of six species (Avicennia marina, Bruguiera gymnorrhiza, B. parviflora, Heritiera littoralis, Xylocarpus australasicus and X. granatum) showed consistently high (>40%) levels of insect damage. Greater than 99% of H. littoralis seeds were attacked by insect predators. The survival and subsequent growth in height and biomass of insect-damaged and non-damaged control seeds/propagules of eight mangrove species were compared in shadehouse experiments. Mangrove species fell into 4 groups with regard to the effect of insect predators on their seeds and seedlings. Xylocarpus australasicus and X. granatum had significantly decreased survival (X 48 and 70%) and growth in height (X 61 and 96%) and biomass (X 66 and 85%). Bruguiera parviflora showed decreased survival (X 59%), but there was no effect of insects on the growth of surviving propagules. In contrast, there was no effect of insect damage on the survival of seedlings of Avicennia marina and Bruguiera exaristata, but decreased growth in height (X 22 and 25%) and biomass (X 22 and 26%). Survival and growth of seedlings of Rhizophora stylosa and Bruguiera gymnorrhiza were not affected. The influence of insect seed predators on the survival and growth of seeds of mangrove species in forests will depend on the relative abundance of seed-eating crabs and intertidal position in mangrove forests.

Prevalence and abundance of equine strongyles (Nematoda: Strongyloidea) in tropical Australia.

Abstract: A postmortem survey of 57 horses in tropical northern Queensland revealed 41 (89%) infected with intestinal strongyles. Thirty-five strongyle species (8 large strongyles and 27 small strongyles [Cyathostominae]) were recorded of which 9 species are reported from Australia for the first time. The 14 most prevalent small strongyles were Cyathostomum catinatum (in 76% of horses), Cyathostomum coronatum (65%), Cyathostomum pateratum (33%), Cyathostomum labiatum (30%), Cylicostephanus calicatus (70%), Cylicostephanus longibursatus (67%), Cylicostephanus goldi (43%), Cylicostephanus minutus (26%), Cylicocylus nassatus (67%), Cylicocyclus leptostomus (41%), Cylicocylus insigne (41%), Cylicocyclus radiatus (33%), Cylicocyclus brevicapsulates (22%), and Poteriostomum imperidentum (24%). The remaining cyathostomes were each found in less than 15% of horses. The 4 most common large strongyles were Triodontophorus serratus (30%), Strongylus vulgaris (28%), Strongylus equinus, and Strongylus edentatus (both 22%). The number of species of small strongyles per horse showed a marked variation (mean 10.3, range 2-21) but bore no relationship to either the total number of strongyles per horse, age, sex, and breed of horse, or season. Total number of strongyles per horse (mean 15,890, range 20-165,000) was less than in recent surveys in Europe and the U.S.A. Most horses had low worm burdens, whereas a very small number were heavily infected. Ninety-seven per cent of the total strongyle counts were small strongyles. Strongylus species contributed just over 1%. Small numbers of large strongyles per horse were usual with T. serratus (mean 570), S. vulgaris (mean 330), and S. equinus (mean 330) the most numerous.(ABSTRACT TRUNCATED AT 250 WORDS)

History and dynamics of the crown-of-thorns starfish Acanthaster planci (L.) in the Suva area, Fiji

Abstract: Annual recruitment of Acanthaster planci over a 13 year period in a known juvenile refuge substratum on Suva Reef was very patchy in time and space. Macroscale recruitment events resulted in outbreaks over many thousands of hectares over 100 km of coastline whereas localised but intensive mesoscale events resulted in concenrated aggregations over areas of several tens of hectares. A very low level of recruitment occurred in most years but three intensive, macroscale recruitment events occurred in 1977, 1984 and 1987, and two localised but intensive recruitment events occurred in 1982 and 1983. Annual recruitment of A. planci between 1975–89 had no overt relationship with rainfall events, as proposed in the terrestrial run-off hypothesis on the cause of primary out-breaks. Growth rates within monitored cohorts were highly variable, but mean growth rates of two cohorts 1984 and 1987 were relatively similar. Mortality rates of three monitored cohorts were variable. Longevity of the 1977 cohort was 7–8 years, while that of the 1984 cohort was 2–3 years. Mortality of the 1987 cohort has been low to date (i.e. 4 years of age). Disease, attributed to an undescribed sporozoan pathogen, was responsible for two mass mortalities in the 1984 cohort, in 1984 and in 1986, and eventually resulted in the extinction of this cohort. Anecdotal reports indicate that outbreaks of A. planci are increasing in frequency and severity. According to Fijian reef fishermen, the starfish were low to moderate in abundance in the Suva area from the 1920s to the 1960s. A progressive build up occurred on some reefs in 1963–67 leading to a major outbreak episode from 1967–1971. The outbreaks were in a chronic phase between 1977–1989. Our findings demonstrate that there is no invariable pattern or process involved in the population dynamics of A. planci and that a single explanation of the A. planci phenomenon is therefore unlikely.

Mitochondrial metabolism following traumatic brain injury in rats.

Abstract: Although a number of studies of traumatic brain injury have implicated mitochondrial dysfunction as a cause of altered posttraumatic energy metabolism, no studies to date have isolated mitochondria and measured their respiratory capacity following trauma. The present study sought to determine whether mitochondrial capacity for oxidative phosphorylation is adversely affected by fluid-percussion-induced traumatic brain injury in rats. Prior to brain injury, the mitochondrial respiratory control ratio was 4.3 ± 0.2 and the ratio of nmoles of ADP phosphorylated per natom oxygen consumed (ADP/O ratio) was 2.66 ± 0.09. After injury (2.8 atm; t= 4 h), there were slight but not significant alterations in ADP/O ratio (2.41 ± 0.07) and state 3 respiratory rate (ADP stimulated); however, there were no changes in the respiratory control ratio. These data suggest that traumatic brain injury, unlike ischemia, does not cause uncoupling of ATP synthesis from respiration, and that brain mitochondria are quite res...

Lack of porphyroblast rotation in the Otago schists, New Zealand: implications for crenulation cleavage development, folding and deformation partitioning

Abstract: Porphyroblasts of garnet and plagioclase in the Otago schists have not rotated relative to geographic coordinates during non-coaxial deformation that post-dates their growth. Inclusion trails in most of the porphyroblasts are oriented near-vertical and near-horizontal, and the strike of near-vertical inclusion trails is consistent over 3000 km2. Microstructural relationships indicate that the porphyroblasts grew in zones of progressive shortening strain, and that the sense of shear affecting the geometry of porphyroblast inclusion trails on the long limbs of folds is the same as the bulk sense of displacement of fold closures. This is contrary to the sense of shear inferred when porphyroblasts are interpreted as having rotated during folding. Several crenulation cleavage/fold models have previously been developed to accommodate the apparent sense of rotation of porphyroblasts that grew during folding. In the light of accumulating evidence that porphyroblasts do not generally rotate, the applicability of these models to deformed rocks is questionable. Whether or not porphyroblasts rotate depends on how deformation is partitioned. Lack of rotation requires that progressive shearing strain (rotational deformation) be partitioned around rigid heterogeneities, such as porphyroblasts, which occupy zones of progressive shortening or no strain (non-rotational deformation). Therefore, processes operating at the porphyroblast/matrix boundary are important considerations. Five qualitative models are presented that accommodate stress and strain energy at the boundary without rotating the porphyroblast: (a) a thin layer of fluid at the porphyroblast boundary; (2) grain-boundary sliding; (3) a locked porphyroblast/matrix boundary; (4) dissolution at the porphyroblast/matrix boundary, and (5) an ellipsoidal porphyroblast/shadow unit.

Heavy metal concentrations in the banana prawn, Penaeus merguiensis, and leader prawn, P. monodon, in the Townsville region of Australia.

Abstract: Trace amounts of heavy metals are normal in marine organisms and some, such as copper, iron, zinc and manganese, are essential for normal growth and development. Other metals such as cadmium and mercury have no known use in physiological processes. In the following study a baseline survey was undertaken to establish the range of metal levels in field populations of juvenile banana prawns Penaeus merguiensis and farmed stocked of juvenile leader prawns, P. monodon. Concentrations of ten trace elements (viz. Cu, Zn, Fe, Mn, Cd, Ag, Mg, Pb, Ni, Co and Hg) were determined in wild and farmed prawn stocks and a preliminary assessment of inter-element relationships within tissues was also made.

Modelling the larval dispersal of Acanthaster planci

Abstract: Numerical models capable of simulating the hydrodynamics associated with large assemblages of reefs are applied to the larval dispersal of Acanthaster planci. Larval distributions which result from passive transportation have been simulated and the resulting patterns of dispersal are compared with the distribution of adults and the observed pattern of Acanthaster population spread. Three forms of asymmetry in reef connectivity are identified within the southern portion of the Cairns Section of the Great Barrier Reef Marine Park. They confirm that larval dispersal within the region cannot be considered as an istropic random process and the recruitment of reefs is not from a homogeneous larval pool. The three forms of asymmetry in the transport of larvae, together with the the longshore currents within the main lagoon, provide a mechanism which results in the passive concentration of larvae adjacent to reefs that border the main lagoon. The three forms of asymmetry are able to account for: (1) the apparent southward spread of Acanthaster populations; (2) the high incidence of “outbreaks” on mid-shelf reefs; and (3) the susceptibility of particular reefs to repeated recruitment. The high incidence of outbreaks on the inner matrix reefs bordering the main lagoon can be explained as a purely physical phenomenon.

The identification of runoff‐production mechanisms using environmental isotopes in a tussock grassland catchment, eastern otago, New Zealand

Abstract: A previous hydrometric study of runoff production in tussock grassland drainage basins in Otago (45°50′S, 169°45′E), New Zealand, revealed a marked change of slope in storm hydrograph recessions. An environmental isotope study was initiated to investigate the runoff mechanisms operating and to test specific hypotheses to explain this break in the hydrograph recession. The results indicated that for quickflow volumes in excess of 10mm, the first part of the storm hydrograph can be attributed to two separate sources, namely, ‘old’ water from a shallow, unconfined groundwater reservoir and ‘new’ water from saturation overland flow on the lower wetlands of concave slopes. Despite the extensive area of wetlands, ‘old’ water runoff from the unconfined groundwater reservoir is delivered more rapidly to the stream than ‘new’ water from saturation overland flow. Substantial surface storage in the wetlands has first to be exceeded before rain becomes a significant part of stream discharge. For quickflow volumes less than 10mm, only ‘old’ water from groundwater contributes to the first part of the hydrograph recession. This means that only the largest 7 per cent of storms (in terms of quickflow volume) generate quickflow containing significant amounts of ‘new water’. The second part of the recession of the storm hydrograph consists of ‘old’ water derived from a remarkably well-mixed shallow unconfined groundwater body.

Opiate antagonist nalmefene improves intracellular free Mg2+, bioenergetic state, and neurologic outcome following traumatic brain injury in rats

Abstract: Treatment of CNS trauma with the opiate antagonist naloxone improves outcome, though the mechanisms of action remain speculative. Nalmefene is another opiate-receptor antagonist, but it has substantially greater potency and duration of action than naloxone. It also has increased activity at kappa opiate receptors and has recently been shown to limit histological changes and neurological dysfunction after traumatic spinal cord injury. The present study examined the effects of treatment with nalmefene on outcome after fluid-percussion-induced traumatic brain injury in rats, using magnetic resonance spectroscopy to monitor acute metabolic changes and behavioral tests to determine chronic neurological recovery. Single-dose treatment with nalmefene (100 micrograms/kg, i.v.) at 30 min after trauma significantly improved (p less than 0.05) neurological outcome (up to 4 weeks) as compared to saline-treated controls. Early changes in intracellular free-magnesium concentration, adenosine diphosphate concentration, and cytosolic phosphorylation potential were all significantly improved by nalmefene treatment, reflecting improved bioenergetic state. We suggest that the ability of nalmefene to improve cellular bioenergetics after trauma may in part account for the neuroprotective effects of this and related compounds.

Ambidentate coordination of the tripyridyl ligands 2,2′:6',2"-terpyridyl, tris(2-pyridyl)-amine, tris(2-pyridyl)methane and tris(2-pyridyl)phosphine to carbonylrhenium centres: structural and spectroscopic studies

Abstract: The reactions of [Re(CO)₅Cl] with the ligands tpy (2,2':6',2"-terpyridine), py₃N {tris(2-pyridyl)-amine}, py₃CH {tris(2-pyridyl)methane}, and py₃P {tris(2-pyridyl)phosphine} in toluene solution realize compounds with the general formulation [Re(ligand)(CO)₃Cl] in which the tripyridyl ligands are bidentate. X-ray structural determinations of fac-[Re(typ)(CO)₃Cl].H₂O and fac-[Re(py₃N)(CO)₃Cl] confirm these assignments. [Re(tpy)(CO)₃Cl].H₂O (C₁₈H₁₃ClN₃O₄Re) is monoclinic, space group P21/n, with cell dimensions a = 7.432(2) A, b = 17.016(4) A, c = 14.466(2) A, β = 93.51(2)°, and Z = 4; full-matrix least-squares refinement on 2435 reflections with I ⩾ 2.5σ(I) converged to a final R = 0.028 and Rw = 0.029. [Re(py₃N)(CO)₃Cl] (C₁₈H₁₂ClN₄O₃Re) is triclinic, space group P1 with cell dimensions a = 13.761(2) A, b = 14.636(6)A, c = 11.110(2) A, α = 110.70(2)°, β = 102.45(2)°, γ = 107.48(2)°, and Z = 4; full-matrix least-squares refinement on 3459 reflections with I ⩾ 2.5σ(I) converged to a final R = 0.038 and Rw = 0.039. If the synthetic procedure is undertaken under irradiation by visible light, for the ligand py₃N a species [Re(py₃N)(CO)₂Cl] (characterized by infrared spectroscopy and conductance measurements) is also formed, in which the ligand py₃N is tridentate. No analogous tridentate species is formed with the ligands tpy or py₃P, although there is evidence that it also forms for py₃CH.

Test of a Model of Regulation of Crown-of-Thorns Starfish by Fish Predators

Abstract: Both a population dynamic model and simplified calculations of the numbers of fish predators that would be required to control heavy recruitment of the coral-eating crown-of-thorns starfish (Acanthaster planci L.) predict threshold densities of fish predators below which starfish population outbreaks may occur. This prediction has been tested through comparable surveys of putative fish predators in the Red Sea, where no major outbreaks of A. planci were found or are known to have occurred, and on the Great Barrier Reef, where two major series of outbreaks have occurred during the last 25 years. In the Red Sea densities of presumed fish predators were found to be well above the predicted threshold. By contrast on the Great Barrier Reef mean densities both of proposed fish predators of juvenile and subadult A. planci, and of know fish predators of adult A. planci, were below the predicted threshold. Moreover the densities of fish predators on four mid-shelf reefs that are believed to have escaped major outbreaks of A. planci were found to be significantly higher than those on otherwise similar but impacted reefs. These data are compatible with the hypothesis that current and recent outbreaks of the crown-of-thorns starfish on the Great Barrier Reef have been facilitated by the presence of only relatively low numbers of fish predators, the numbers of which may have been decreased as a result of the intensification of fishing pressure that has occurred from the 1960s onwards.

Comparison of larval duration and pre- and post-settlement growth in two species of damselfish, Chromis atripectoralis and Pomacentrus coelestis (Pisces : Pomacentridae), from the Great Barrier Reef

Abstract: Light traps were used to capture larval fishes, immediately before settlement, at two localities 500 km apart on the Great Barrier Reef (GBR) in December, 1987. Samples from Lizard Island, in the northern GBR, and Davies Reef, in the central GBR, were dominated by two species of damselfish:Chromis atripectralis andPomacentrus coelestis. Analysis of otoliths revealed significant differences in both size and age at settlement between the two localities forP. coelestis, but not forC. atripectoralis. Growth rates determined for pre- and post-settlementP. coelestis suggested a sigmoidal growth trajectory through the larval life, with growth slowing as fishes approached the time of settlement. Post-settlement growth rates were faster than growth prior to settlement in both species. Growth in both species was, however, similar between localities. The relationship between fish size and otolith size was complex, varying both between pre- and post-settlement fishes, and among localities. This emphasizes the need to validate the relationship between fish size and otolith size before otoliths may be used to back-calculate individual growth trajectories.