Oxygen detoxification in algal-invertebrate symbioses from the Great Barrier Reef

Summary Examination of 34 species of symbiotic invertebrates in four phyla has confirmed the generality of a direct relationship between chlorophyll concentration and the activities of superoxide dismutase and catalase, two enzymes involved in the detoxification of active oxygen. On a finer scale, activities of these enzymes also depend on the localization of the algal symbions (intracellular or extracellular) and hence on the extent to which photosynthetic O₂ actually contacts animal cytoplasm, and on the solar irradiance experienced by the symbionts. Differences in SOD activity among organs of Tridacna crocea are not fully explained by local O₂ levels but are further related to organ-specific retes of O₂ consumption. This result is discussed in terms of known mechanisms of superoxide radical production in mitochondria and differences in O₂ utilization concentrations among various organs in bivalve molluscs.     

Halimeda bioherms of the northern Great Barrier Reef

The reefless tract directly behind the ribbon reefs on the outer shelf off Cooktown supports a luxuriant growth of Halimeda that, during the Holocene, has developed into bioherms. These mounded biodies of unconsolidated sediment have formed banks that vary in height between 2 and 20 m. Combined shallow, high-resolution seismic reflection profiles and side-scan sonar have diferentiated three areas of biohermal complexes behind the ribbon reefs of Cooktown. Observations by SCUBA and submersible plus the sedimentology of the bioherms indicate that they are in situ accumulations. Evidence from dating of cores suggests that the Halimeda bioherms began to grow about 10 000 years B.P. and their growth has continued to the present time, even though their tops are presently restricted to a depth of -20 m. It is suggested that the origin and morphology of the bioherms are related to a specific hydrodynamic phenomenon, involving jets of nutrient-rich, upwelled oceanic water intruding onto the outer shelf via the narrow passes between the ribbon reefs, and forming eddies behind the ribbons.     

Endosymbiotic Umagillids (Turbellaria) from Holothurians of the Great Barrier Reef

Seven new species of umagillid turbellarians from the intestine of aspidochirote holothurians of the Great Barrier Reef are described: Cleistogamia heronensis sp.n., C. longicirrus sp.n., C. pulchra sp.n., C. pallii sp.n., C. pyriformis sp.n. and Wahlia stichopi sp.n. as well as Paranotothrix queenslandensis gen.n. sp.n. The new genus is recognized as distinct from Notothrix Hickman, 1955 because the female system lacks a bursal valve, a significant characteristic within the Umagillidae. Examination of this and other characteristics of the family reveal that the division of the family by Stunkard & Corliss in 1950 into the sub-families Collastominae Wahl, 1910, Bicladinae Stunkard & Corliss, 1950 and Umagillinae Wahl, 1910 is supported; further, within the Umagillinae, four subgroups may be recognized: within holothurians are ( i ) the Cleistogamia group with a secondary uterus, within this group Ozametra elegans and O. striata are placed in Seritia gen.n. differing from Ozametra by the presence of both a bursal valve and a cuticular stylet, ( ii ) the Anoplodium group with a single ovary and a muscular (not cuticular) male intromittent organ and ( iii ) the Umagilla group in which Monticellina longitubu becomes a junior synonym of U. forskalensis; within echinoids ( iv ) the Syndesmis group in which Syndisyrinx is recognized a valid genus for those worms with a bursal valve and Syndesmis for those lacking this structure. Marcusella is suppressed. A visual key based upon presumed primitive and derived states is given as is a full host check list of the Umagillidae.     

Towards protecting the Great Barrier Reef from land‐based pollution

The Great Barrier Reef (GBR) is an iconic coral reef system extending over 2000 km along the north‐east coast of Australia. Global recognition of its Outstanding Universal Value resulted in the listing of the 348 000 km² GBR World Heritage Area (WHA) by UNESCO in 1981. Despite various levels of national and international protection, the condition of GBR ecosystems has deteriorated over the past decades, with land‐based pollution from the adjacent catchments being a major and ongoing cause for this decline. To reduce land‐based pollution, the Australian and Queensland Governments have implemented a range of policy initiatives since 2003. Here, we evaluate the effectiveness of existing initiatives to reduce discharge of land‐based pollutants into the waters of the GBR. We conclude that recent efforts in the GBR catchments to reduce land‐based pollution are unlikely to be sufficient to protect the GBR ecosystems from declining water quality within the aspired time frames. To support management decisions for desired ecological outcomes for the GBR WHA, we identify potential improvements to current policies and incentives, as well as potential changes to current agricultural land use, based on overseas experiences and Australia's unique potential. The experience in the GBR may provide useful guidance for the management of other marine ecosystems, as reducing land‐based pollution by better managing agricultural sources is a challenge for coastal communities around the world.     

Reproductive biology of a new hesionid polychaete from the Great Barrier Reef

We describe Lizardia hirschi, a new hesionid genus and species, from shallow water on the Great Barrier Reef. It is characterized by small size (maximally around 2 mm long) and by males with paired penes on the last segment or the pygidium. The sperm are elongated, with a conical acrosome; extended, cylindrical nucleus; and three mitochondria. The females have three to four pairs of eggs in segments 10-13, up to 150 microm in diameter. The female reproductive system consists of spermathecae, situated in the notopodia of segments 10-12, and oviducts opening ventrally on segment 11. Fertilization may be internal. The female (but not the male) reproductive system appears to be homologous to that in another small hesionid, capricornia. The phylogenetic position of L. hirschi within Hesionidae is currently uncertain due to the retention of many apparently larval features in the adults.     

Observations of wind-driven surface gravity waves offshore from the Great Barrier Reef

A 3 month long record of pressure from a nearsurface-resident instrument deployed at 18° S at the Queensland shelf break, offshore from the Great Barrier Reef, has been analysed. No discrete wind-sea and swell spectra can be identified, nor is there evidence for frequency-dependent wave dispersion. The wave spectral width and significant wave height are strongly related to local meteorological events, and the response appears to be both fetch limited and wind duration dependent. A near-gale sea state on the Beaufort scale is experienced during strong trade winds. It is suggested that waves make an important contribution to the physical oceanography, the geomorphology and the ecology of coral reefs near the shelf break of the Great Barrier Reef.     

Actinosporeans (Myxozoa) from marine oligochaetes of the Great Barrier Reef

Four species of actinosporeans are described from marine oligochaetes (all Tubificidae) from the Great Barrier Reef, Queensland, Australia. They developed in the coelom of the oligochaete and produced spores in groups of eight in the pansporocysts. The new genus Endocapsa is proposed within the family Sphaeractinomyxidae Janiszewska, 1957 on the basis that mature spores have small valve cell processes and non-protruding polar capsules. The type-species, Endocapsa rosulata n. sp., has three valve cell processes, which resemble a rosette, and submerged polar capsules. It infected Heterodrilus cf. keenani from Heron Island and morphologically similar parasites occurred in Thalassodrilides cf. gurwitschi and Heronidrilus sp. from Lizard Island. E. stepheni n. sp. has asymmetrical valve cell processes and submerged polar capsules. It was found in H. cf. keenani and H. queenslandicus from Heron Island. Sphaeractinomyxon leptocapsula n. sp. has thin widely spaced polar capsules and is described from Heronidrilus sp. from Lizard Island. S. ersei Hallett, O'Donoghue & Lester, 1998 infected Tubificidae gen. sp. from Heron Island and S. cf. ersei occurred in Bathydrilus sp., Thalassodrilides cf. gurwitschi and Limnodriloides lateroporus from Lizard Island.     

Impacts and Recovery from Severe Tropical Cyclone Yasi on the Great Barrier Reef

Full recovery of coral reefs from tropical cyclone (TC) damage can take decades, making cyclones a major driver of habitat condition where they occur regularly. Since 1985, 44 TCs generated gale force winds (≥17 metres/second) within the Great Barrier Reef Marine Park (GBRMP). Of the hurricane strength TCs (≥H1—Saffir Simpson scale; ≥ category 3 Australian scale), TC Yasi (February, 2011) was the largest. In the weeks after TC Yasi crossed the GBRMP, participating researchers, managers and rangers assessed the extent and severity of reef damage via 841 Reef Health and Impact Surveys at 70 reefs. Records were scaled into five damage levels representing increasingly widespread colony-level damage (1, 2, 3) and reef structural damage (4, 5). Average damage severity was significantly affected by direction (north vs south of the cyclone track), reef shelf position (mid-shelf vs outer-shelf) and habitat type. More outer-shelf reefs suffered structural damage than mid-shelf reefs within 150 km of the track. Structural damage spanned a greater latitudinal range for mid-shelf reefs than outer-shelf reefs (400 vs 300 km). Structural damage was patchily distributed at all distances, but more so as distance from the track increased. Damage extended much further from the track than during other recent intense cyclones that had smaller circulation sizes. Just over 15% (3,834 km²) of the total reef area of the GBRMP is estimated to have sustained some level of coral damage, with ~4% (949 km²) sustaining a degree of structural damage. TC Yasi likely caused the greatest loss of coral cover on the GBR in a 24-hour period since 1985. Severely impacted reefs have started to recover; coral cover increased an average of 4% between 2011 and 2013 at re-surveyed reefs. The in situ assessment of impacts described here is the largest in scale ever conducted on the Great Barrier Reef following a reef health disturbance.     

Large-scale bleaching of corals on the Great Barrier Reef

 The Great Barrier Reef (GBR) experienced its most intensive and extensive coral bleaching event on record in early 1998. Mild bleaching commenced in late January and intensified by late February/early March 1998. Broad-scale aerial surveys conducted of 654 reefs (∼23% of reefs on the GBR) in March and April 1998, showed that 87% of inshore reefs were bleached at least to some extent (>1% of coral cover) compared to 28% of offshore (mid- and outer-shelf) reefs. Of inshore reefs 67% had high levels of bleaching (>10% of coral) and 25% of inshore reefs had extreme levels of bleaching (>60% of coral). Fewer offshore reefs (14%) showed high levels of bleaching while none showed extreme levels of bleaching. Ground-truth surveys of 23 reefs, which experienced bleaching in intensities ranging from none to extreme, showed that the aerial survey data are likely to be underestimates of the true extent and intensity of bleaching on the GBR. The primary cause of this bleaching event is likely to be elevated sea temperature and solar radiation, exacerbated by lowered salinity on inshore and some offshore reefs in the central GBR. Accepted: 30 July 1998     

New and noteworthy plants from Great Barrier Reef sand cays,Australia

Observations are presented on new and critical plants from the northern sand cays on the Great Barrier Reef, Queensland, Australia, based mainly on recent collections made by David R. Stoddart and Ralf Buckley. New species and varieties are described:Lepturus stoddartii (Poaceae),Boerhavia fistulosa var.fistulosa and var.puberuliflora (Nyctaginaceae),Boerhavia albiflora var.heronensis, Spermacoce everistiana (Rubiaceae), andSpermacoce buckleyi; a new combination is made:Diospyros ferrea var.compacta (R. Br.) (Ebenaceae); and additional taxonomic notes are given onBoerhavia, Euphorbia (Euphorbiaceae), andAbutilon (Malvaceae).     

Dynamics of phytoplankton in the Great Barrier Reef Lagoon

The characteristics of the phytoplankton crop in the centralregion of the Great Barrier Reef were analyzed through two annualcycles together with basic oceanographic parameters. Chlorophylla standing crop and primary production were size fractionatedinto nanoplankton and microplankton components. Community compositionwas determined using the Utermöhl settling technique andcommunity diversities estimated by the Shannon-Weaver equation.The data and analysis are the most comprehensive in existencefor the region, and the first detailed study since the 1928–29Great Barrier Reef expedition. A marked seasonal cycle was identified,contrary to most assumptions, closely associated with precipitationpatterns and nutrients introduced by land drainage. The regionwould rank as mesotrophic with some eutrophic areas in the innerreaches of the Lagoon. Oscillatoria spp. accounted for a largefraction of the majority of phytoplankton maxima and were inverselyrelated to diatom crop densities even under conditions favoringdiatom growth. Microplankton crop species diversities usuallydecreased during extended Oscillatoria blooms. The reduced diversitypersisted after the bloom suggesting that Oscillatoria spp.were the source of extracellular metabolites and/or decompositionproducts adversely influencing diatom microplankton.     

Picoplankton dynamics in Davies Reef lagoon, the Great Barrier Reef, Australia

The diel variations in abundance and frequency of dividing cells(FDC) of coccoid cyanobacteria in a coral reef lagoon were investigatedin June, September and December 1989, and April 1990. Cyanobacteriaand picoplanktonic eukaryotes (<3 µm) were sampledmonthly from January to December 1990. The average abundancesof cyanobacteria and eukaryotes ranged between 1.17–10.0610⁴cells ml^–1 and 0.16–2.4110⁴ cells ml^–1, respectively,with abundances of both being higher in summer (November-April)than in winter (May-October). The ratio of cyanobacteria toeukaryotes fluctuated from 1.93 to 8.67, independent of theseasonal variation in their abundances. The instantaneous growthrate of cyanobacteria, which was estimated from the daytimeabundance increment, ranged between 0.430 and 3.144 day^–1The estimated daily specific growth rate of cyanobacteria bythe FDC method ranged between 0.231 and 0.966 day^–1. InApril, despite the high specific growth rate and low flushingconditions. cyanobacterial abundance showed a cyclic diel pattern,suggesting a strong grazing impact on their population.     

Suppressing the next crown-of-thorns outbreak on the Great Barrier Reef

Coral Reefs - Crown-of-thorns starfish (COTS) outbreaks are a globally significant driver of coral mortality in the Indo-Pacific and work synergistically with other disturbances. We argue that our...     

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.