Transport mechanisms and the potential movement of planktonic larvae in the central region of the Great Barrier Reef

It is suggested that considerable inter-reef dispersal of reef fishes and many benthic invertebrates is likely in the central region of the Great Barrier Reef. Larvae are most abundant in spring-summer when currents on the outer shelf, where most of the coral reefs occur, are almost entirely unidirectional and southeastward (longshore). Net drift on the outer shelf at this time is likely to be greater, but the dispersion smaller, than that nearshore at the same time due to more extensive periodic reversals of water movement in the latter area than the former. Net drift on the outer shelf in winter will be significantly more restricted, but the dispersion greater, than in summer due to extensive periodic reversals of currents in this area during the trade wind (winter) season. These conclusions suggest that reefs within the Central Great Barrier Reef are biologically interconnected and interdependent; a result of considerable significance for management of reefs within the Great Barrier Reef marine park.Australian Institute of Marine Science Contribution No. 250     

Currents and flusing of Britomart reef lagoon,Great Barrier Reef

Currents, sea levels and weather were measured for a 60 d period at a number of sites in and near Britomart reef, Great Barrier Reef. The tidal currents were primarily semi-diurnal in character. The lowfrequency currents were due to a simple balance, in the longshore direction, between the wind stress and the bottom frictional stress, and, in the cross-shelf direction, between the bottom frictional stress and the pressure gradient generated by the passage of wind-driven continental shelf waves. The bottom friction coefficient, for the nonlinear drag law, is estimated to be of the order of 0.02. By contrast, the currents over the surrounding continental shelf are primarily controlled by continental shelf wave dynamics and are not dominated by friction. It thus appears that the water bodies in, respectively, the reef matrix and the Lagoon of the Great Barrier Reef are relatively uncoupled. Tidal and low-frequency currents contributed roughly equally to the flushing of Britomart reef lagoon with an estimated flushing time of the order of 4 d.     

Restricted terrestrial carbon input to the continental shelf during Cyclone Winifred: implications for terrestrial runoff to the Great Barrier Reef Province

Tropical Cyclone Winifred (1 February 1986) provided an ideal opportunity to examine the fate of high river discharge in the Central Great Barrier Reef by producing near-record floods between Townsville and Cairns. Comparison of the carbon isotope ratio of organic matter in shelf sediment collected immediately before and after the cyclone showed that the bulk of terrestrial plant detritus from the Johnstone River was deposited within 2 km of the rivermouth and none moved more than 15 km offshore. By comparing the magnitude of the Johnstone River flow to the maximum recorded flows on other rivers in the Great Barrier Reef Province, we conclude that terrestrial runoff has not reached the Reef in historical times except, perhaps, during rare Burdekin River floods. Terrestrial detritus initially deposited near chore, however, is resuspended during tropical cyclones and may eventually be transported to the Reef.     

Dactylogyrids (Monogenoidea) parasitizing the gills of spinefoots (Teleostei: Siganidae): proposal of Glyphidohaptor n. gen., with two new species from the Great Barrier Reef, Australia, and G. plectocirra n. comb. from Ras Mohammed National Park, Egypt

Nine species of Siganus (Perciformes: Siganidae) were examined for dactylogyrids (Monogenoidea) from the Red Sea, Egypt; the Great Barrier Reef, Australia; and the South China Sea, China. Species of Tetrancistrum were found on siganids from all 3 localities; Pseudohaliotrema spp. were restricted to siganids from the Great Barrier Reef; and species representing Glyphidohaptor n. gen. were found on siganids from the Red Sea and Great Barrier Reef. Siganus argenteus from the Red Sea and Siganus vulpinus from the Great Barrier Reef were negative for dactylogyrid parasites. Glyphidohaptor n. gen. is proposed for 3 species (2 species new to science) and the new species are described: Glyphidohaptor phractophallus n. sp. from Siganus fuscescens from the Great Barrier Reef; Glyphidohaptor sigani n. sp. from Siganus doliatus (type host), Siganus punctatus, Siganus corallinus, and Siganus lineatus from the Great Barrier Reef; and Glyphidohaptor plectocirra (Paperna, 1972) n. comb. (= Pseudohaliotrema plectocirra Paperna, 1972) from Siganus luridus and Siganus rivulatus from the Red Sea.     

Significance of <Emphasis Type="Italic">Halimeda</Emphasis> bioherms to the global carbonate budget based on a geological sediment budget for the Northern Great Barrier Reef,Australia

Since the correlation between carbon dioxide (CO₂) levels and global temperatures was established in the ice core records, quantifying the components of the global carbon cycle has become a priority with a view to constraining models of the climate system. The marine carbonate budget is still not adequately constrained and the quantitative significance of the calcareous green alga Halimeda still remains particularly poorly understood. Previously, it has been suggested that Halimeda bioherms on the shelf of the Great Barrier Reef may contain a volume of carbonate equal to or greater than that contained within the shelf edge coral reefs. This study uses published datasets to test this hypothesis in the Northern Great Barrier Reef (NGBR) province. It is estimated that Halimeda bioherms on the outer shelf of the NGBR contain at least as much (and up to four times more) CaCO₃ sediment as the adjacent ribbon reef facies. Globally, if these findings are even only partially applicable, the contribution of shallow water carbonate sediments to the global carbon budget based on coral reefs alone is currently substantially underestimated.     

Long-term observations of currents on the central Great Barrier Reef continental shelf

Time-series are presented of wind, sea levels, currents and temperature in the central region of the Great Barrier Reef continental shelf over the period 1980 to 1982 (inclusive). Except for occasional periods of calm weather or during the passage of tropical cyclones, the wind was alternately southwestward or northwestward, with periods of several days to several weeks. The fluctuations of the low-frequency sea level, longshore current and wind components, but not temperature, were highly coherent over distances >400 km longshore and over the shelf width. The temperature and the atmospheric pressure controlled much of the seasonal changes in the sea level. A simple model for wind-driven circulation using a non-linear bottom friction law is able to account for most of the variance of the currents with perios <20 days. An additional poleward base flow was present at all sites, probably driven by the circulation in the Coral Sea. There were also large interannual variations, possibly associated with the El Niño Southern Oscillation phenomena. These observations imply that the advection and dispersion over the Great Barrier Reef of fish eggs and larvae, coral planulae etc., and hence reef recruitment, experience considerable variability at time scales of days of years.     

Measurement and modelling of tropical cyclone waves in the Great Barrier Reef

Recorded wave data from four wave measuring instruments located at various points within a section of the Great Barrier Reef during the passage of a tropical cyclone are presented. A spectral wave prediction model is used as an aid to the interpretation of the data. The tropical cyclone generated significant wave heights of approximately 10 m seaward of the reef complex. The many scattered reefs, however, act to reduce this value to approximately 6 m landward of the reef complex. Individual reefs appear to act as complete barriers to waves at typical oceanic periods, even at high tide. In a scattered reef complex such as the Great Barrier Reff, wave energy can penetrate the inter-reef gaps. Although such inter-reef gaps may appear large in comparison to the sizes of individual reefs, wave attenuation is still significant.     

Assessment of the eutrophication status of the Great Barrier Reef lagoon (Australia)

Current scientific consensus is that inshore regions of the central and southern Great Barrier Reef, Australia, are at risk of impacts from increased nutrient (as well as sediment and pesticide) loads delivered to Reef waters. Increases in the discharge of water quality contaminants to the Reef are largely a consequence of the expansion of agricultural practices in northern Queensland catchments following European settlement in the 1850s. In particular, the presence of elevated chlorophyll a and nutrient concentrations in many parts of the inshore Great Barrier Reef together with intense and extensive phytoplankton blooms following the discharge of nutrient-rich river flood waters suggest that the central and southern inshore area of the Great Barrier Reef is likely to be significantly impacted by elevated nutrient loads. The biological consequences of this are not fully quantified, but are likely to include changes in reef condition including hard and soft coral biodiversity, macroalgal abundance, hard coral cover and coral recruitment, as well as change in seagrass distribution and tissue nutrient status. Contemporary government policy is centered around promotion and funding of better catchment management practices to minimize the loss of catchment nutrients (both applied and natural) and the maintenance of a Reef wide water quality and ecosystem monitoring program. The monitoring program is designed to assess trends in uptake of management practice improvements and their associated impacts on water quality and ecosystem status over the next 10 years. A draft set of quantitative criteria to assess the eutrophication status of Great Barrier Reef waters is outlined for further discussion and refinement.     

Latitudinal variation in coral communities in eastern Australia: a qualitative biophysical model of factors regulating coral reefs

The processes underlying the distributional limits of both corals and coral reefs can be elucidated by examining coral communities at high latitudes. Coral-dominated communities in eastern Australia cover a latitudinal range of >2,500 km, from the northern Great Barrier Reef (11°S) to South West Rocks (31.5°S). Patterns of coral species richness from 11 locations showed a clear separation between the Great Barrier Reef and subtropical sites, with a further abrupt change at around 31°S. Differences in community structure between the Great Barrier Reef and more southern sites were mainly attributable to higher cover of massive corals, branching Acropora, dead coral and coralline algae on the Great Barrier Reef, and higher cover of macroalgae and bare rock at more southern sites. The absence of some major reef-building taxa (i.e., staghorn Acropora and massive Porites) from most subtropical sites coincided with the loss of reef accretion capacity. Despite high cover of hard corals in communities at up to 31°S, only Lord Howe Island contained areas of reef accretion south of the Great Barrier Reef. Factors that have been hypothesized to account for latitudinal changes in coral community structure include water temperature, aragonite saturation, light availability, currents and larval dispersal, competition between corals and other biota including macroalgae, reduced coral growth rates, and failure of coral reproduction or recruitment. These factors do not operate independently of each other, and they interact in complex ways.     

Taxonomy, host specificity and dietary implications of Hurleytrematoides (Digenea: Monorchiidae) from chaetodontid fishes on the Great Barrier Reef

Five new and five previously described species of Hurleytrematoides are reported from 19 of 34 chaetodontid species examined from the Great Barrier Reef; new species are H. faliexae n. sp., H. galzini n. sp., H. loi n. sp., H. morandi n. sp., and H. sasali n. sp. Previously described species are H. coronatum, H. fijiensis, H. prevoti, H. bartolii, and H. zebrasomae. The genus is rediagnosed in the light of morphological variation of the new species; the degree of spination and shape of the terminal genitalia distinguish individual species. Species of Hurleytrematoides infect almost every clade of the family Chaetodontidae found on the Great Barrier Reef, but obligate corallivores are not infected. All ten species were found at Heron Island on the southern Great Barrier Reef, but only six at Lizard Island on the northern Great Barrier Reef. For three of the four species not present at Lizard Island, the absence appears to be statistically significant. Although all species are apparently restricted to chaetodontids on the GBR, specificity within the family varies from oioxenous to euryxenous; a core/satellite host paradigm explains the distribution of several species.     

Predicting the Location and Spatial Extent of Submerged Coral Reef Habitat in the Great Barrier Reef World Heritage Area,Australia

Aim

Coral reef communities occurring in deeper waters have received little research effort compared to their shallow-water counterparts, and even such basic information as their location and extent are currently unknown throughout most of the world. Using the Great Barrier Reef as a case study, habitat suitability modelling is used to predict the distribution of deep-water coral reef communities on the Great Barrier Reef, Australia. We test the effectiveness of a range of geophysical and environmental variables for predicting the location of deep-water coral reef communities on the Great Barrier Reef.

Location

Great Barrier Reef, Australia.

Methods

Maximum entropy modelling is used to identify the spatial extent of two broad communities of habitat-forming megabenthos phototrophs and heterotrophs. Models were generated using combinations of geophysical substrate properties derived from multibeam bathymetry and environmental data derived from Bio-ORACLE, combined with georeferenced occurrence records of mesophotic coral communities from autonomous underwater vehicle, remotely operated vehicle and SCUBA surveys. Model results are used to estimate the total amount of mesophotic coral reef habitat on the GBR.

Results

Our models predict extensive but previously undocumented coral communities occurring both along the continental shelf-edge of the Great Barrier Reef and also on submerged reefs inside the lagoon. Habitat suitability for phototrophs is highest on submerged reefs along the outer-shelf and the deeper flanks of emergent reefs inside the GBR lagoon, while suitability for heterotrophs is highest in the deep waters along the shelf-edge. Models using only geophysical variables consistently outperformed models incorporating environmental data for both phototrophs and heterotrophs.

Main Conclusion

Extensive submerged coral reef communities that are currently undocumented are likely to occur throughout the Great Barrier Reef. High-quality bathymetry data can be used to identify these reefs, which may play an important role in resilience of the GBR ecosystem to climate change.     

Faustulid trematodes (Digenea) from marine fishes of Australia

Twelve species of faustulid trematode are described or redescribed from Australian marine fishes. Bacciger lesteri Bray, 1982 and B. sprenti Bray, 1982 are redescribed from Selenotoca multifasciata from Moreton Bay. It is suggested that the original host record for these species, Mugil sp., was incorrect. The genera Discogastroides, Odontocotyle and Pseudodiscogasteroides are synonymised with Paradiscogaster. The new combinations Paradiscogaster arabi (Hafeezullah & Siddiqi, 1970), P. hainanensis (Shen, 1970), P. indicus (Srivastava, 1939), P. macrostomus (Shimazu & Kamegai, 1990), P. ostracii (Yamaguti, 1934) and P. pritchardae (Gupta & Ahmad, 1978) are proposed. Discogasteroides hawaiensis Hanson, 1955 is synonymised with P. ostracii. P. macrostomus and P. ostracii are redescribed from Ostracion meleagris and O. cubicus from the Great Barrier Reef. P. farooqii Hafeezullah & Siddiqi, 1970 is redescribed from Monodactylus argenteus from Moreton Bay. The following new species are described: P. machidai n. sp. from Pomacanthus semicirculatus and P. sexstriatus from the Great Barrier Reef, P. dweorg n. sp. from Meuschenia galii, P. lobomyzon n. sp. from Tilodon sexfasciatus and P. habilis n. sp. from Pelates octolineatus, all from Western Australia. Antorchis pomacanthi (Hafeezullah & Siddiqi, 1970) Machida, 1975 is redescribed from Pomacanthus semicirculatus and P. sexstriatus from the Great Barrier Reef. The new combination Antorchis intermedius (Madhavi, 1975) is proposed for Parantorchis intermedius. Parayamagutia ostracionis is redescribed from O. cubicus from the Great Barrier Reef. Trigonocryptus conus is redescribed from Arothron hispidus from South-east Queensland and from A. nigropunctatus from the Great Barrier Reef. The new combination Trigonocryptus australiensis (Kurochkin, 1970) is proposed for Pseudodiscogasteroides australiensis. The Echinobrevicecinae is reduced to synonymy with the Faustulidae.     

Patterns in the use of space by benthic communities on two coral reefs of the Great Barrier Reef

A rapid benthic line-transect survey method for use by non-specialist observers is described. At both Davies Reef (mid-continental shelf) and Myrmidon Reef (outer-continental shelf) in the central Great Barrier Reef a set of 6 sites of varying depths on the reef flat, crest and slope were sampled using this method. At least 10 contiguous 10 m transects were made at each site. Benthic organisms were recorded as life forms with categories based on both high level taxa and morphologies, and including scleractinian corals, alcyonarians, sponges, algae and others. Percentage cover data for 19 benthic categories are presented for all sites. Coral cover on both reefs is high on the crest and slope but low on the reef flat. At all sites the cover of soft corals and sponges is much less than cover of hard corals and algae. Abundances of soft corals and sponges increase with depth. Analysis of gaps between hard corals show that many colonies grow close to each other (<1 cm)even when total coral cover is low.     

Aspects of the ecology of the coral-eating starfish Acanthaster planci

In the central region of the Great Barrier Reef, Acanthaster planci eats its own disk area of coral each day. At the southern end of the reef lagoon populations of A. planci eat substantially less than this amount of coral per day. Branching and plate corals are preferred food species and massive and encrusting forms are rejected while the preferred food species are available. Only when branching and plate forms on a reef have been consumed will A. planci attack massive and encrusting species. On Australian reefs preferred food species form between 70–99% of the coral cover.
On the Great Barrier Reef A. planci spawns in January and juveniles settle in the top 3 m of water on the windward edge of reefs or on isolated patch reefs behind the main reef. Intolerance of wave attack forces the growing starfish to migrate into deeper water. Lateral movements, probably induced by shortage of living coral in deep water, bring the starfish around the ends of the reef to the leeward side. Here they destroy most of the living coral.
It is suggested that the visual impact of A. planci on reefs of the Indo-Pacific region is related to the composition of the coral fauna. Reefs with a high proportion of preferred food species will be severely damaged while those with faunas composed mainly of massive and encrusting forms will not be altered greatly by starfish predation.
Work on larval development of A. planci carried out by Henderson & Lucas, 1971 showed that metamorphosis took place only at water temperatures of 28^o -29^o C. This suggests that the A. planci plague on the Great Barrier Reef will not spread south of latitude 20^o S (29^o C isotherm in January).     

Some nemerteans (Nemertea) from Queensland and the Great Barrier Reef, Australia

Three species of marine nemerteans described and illustrated from Queensland and the Great Barrier Reef, Australia, include one new genus and two new species: these are the monostiliferous hoplonemerteans Thallasionemertes leucocephala gen. et sp. nov. and Correanemertes polyophthalma sp. nov. A new colour variety of the heteronemertean Micrura callima is also reported, this species previously only being known from Rottnest Island, Western Australia. A key for the field identification of the marine nemerteans recorded from coastal Queensland and the Great Barrier Reef is provided.     

Recruitment patterns of scleractinian corals in an isolated sub-tropical reef system

The density of recruits of scleractinian corals on settlement plates at Lord Howe Island, a small isolated sub-tropical island 630 km off the Australian coastline, was within the range of values reported for comparable studies on the Great Barrier Reef. However, there was a difference in the relative abundance of taxonomic groups, with recruitment at Lord Howe Island during the summer of 1990/91 dominated by corals from the Family Pocilloporidae, Family Poritidae, and sub-genus Acropora (Isopora) (in order of abundance). By contrast, on the Great Barrier Reef, recruits are generally predominantly species from the Family Acroporidae (other than the Acropora (Isopora) group). Both the recruits and the established coral communities at Lord Howe Island are dominanted by corals which release brooded planulae, as opposed to the pattern of mass-spawning with external fertilisation more typical of Great Barrier Reef corals. I hypothesise that the release of brooded planulae would be advantageous in an isolated reef community because (a) brooded larvae can travel large distances and survive the journey to the isolated reef and/or (b) brooded larvae have a shorter period before they are competent to settle and are therefore more likely to be retained on the parental reef once a population has been established.     

Form and seismic stratigraphy of Halimeda banks in part of the northern Great Barrier Reef Province

Twenty-six percent of the total shelf area in the Northern Region of the Great Barrier Reef Province between latitudes 14°27 and 15°02S is occupied by algal (Halimeda) lithofacies. Sea-bed relief over this bankforming algal lithofacies, which dominates the outer shelf, is generally complex and variable over relatively short distances, but lateral continuity of morphological features near Petricola and Stewart shoals has been demonstrated by parallel profiling. The most prominent subbttom reflector is a pre-Holocene erosion surface, regarded as the Holocene/Pleistocene unconformity. In this area, the maximum thickness of Holocene Halimeda banks above the main subbottom reflector is 19 m. Seismic response suggests three main sequences in the Halimeda bank depostis, which probably relate to changes in environmental conditions, and the recognition of similar seismic characteristics in the deposits beneath the Holocene/Pleistocene unconformity indicates that Halimeda banks may have been a feature of the outer shelf of the Great Barrier Reef in Plesitocene times.     

Two new species ofCerioxynus (Copepoda: Poecilostomatoida) parasitic in corals (Scleractinia: Faviidae) in the South Pacific

Summary The copepodsCerioxynus oulophylliae n. sp., parasitizing the hard coralOulophyllia crispa (Lamarck) on the Great Barrier Reef, Australia, and at Banda in the Moluccas, andCerioxynus montastreae n. sp., living inMontastrea curta (Dana) on the Great Barrier Reef, are described and illustrated. Both new species are distinguished from their four congeners by having wing-like epimera on the segments bearing leg 2 and leg 3. ac]19850419     

Ostracoda (Crustacea) from Lizard Island,northern Great Barrier Reef,Australia. II. The family Paradoxostomatidae Brady & Norman, 1889

The present paper deals with the taxonomy of the ostracod family Paradoxostomatidae Brady & Norman, 1889 from the coral reefs around Lizard Island, northern Great Barrier Reef, Australia. 18 species were found, all of them belonging to the genusParadoxostoma Fischer, 1855. 2 species had been previously described from Heron Island, southern Great Barrier Reef. 1 species had been described from the Red Sea. 2 species are left in open nomenclature.