Clive Wilkinson

Global Coral Reef Monitoring Network · Coral Reefs

coral reefs

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The keynote paper by Garrett Hardin 44 years ago introduced the term 'tragedy of the commons' into our language (Hardin, 1968); this term is now used widely, but it is neither universally accepted nor fully understood. Irrespective, the 'tragedy of the commons' is an increasing reality for more than 500 million people that rely on the biodiversity...

Tropical cyclones occur relatively frequently throughout the South Pacific with resultant changes to coral reefs and low lying coral islands. Cyclones can result in both accumulation of coral rock, rubble and sand to parts of coral reefs, whereas there can be severe damage and erosion to other parts of reefs and islands. Many coral reef islands owe...

This report presents the results obtained within the framework of the crisp programme in terms of progressing knowledge on the structure and functioning of coral reefs for the years 2006 and 2007. It gathers newly achieved understanding of coral reefs on a general level and at the scale of the Pacific. It is not a report on crisp activities per se...

Southeast Asia, an economically ‘emerging’ region, contains the world's most outstanding and diverse tropical marine resources. The conservation of this biodiversity is essential both for global ecological health and the economic future of the members of the Association of Southeast Asian Nations. However, these resources are now severely threatene...

The marine alga Ceratodictyon spongiosum Zanardini, known only in nature in symbiotic association with a haplosclerid sponge, was isolated into unialgal culture for the first time. Protracted vegetative development took place in simple inorganic medium in the absence of the sponge. Cultured specimens transplanted into the field have not survived.

The Sulu-Sulawesi Sea, with neighboring Indonesian Seas and South China Sea, lies at the center of the world's tropical marine biodiversity. Encircled by 3 populous, developing nations, the Philippines, Indonesia and Malaysia, the Sea and its adjacent coastal and terrestrial ecosystems, supports ca. 33 million people, most with subsistence liveliho...

Colonization abilities of the bioeroding sponge Cliona orientalis were studied in a field experiment conducted at Orpheus Island, on the central Great Barrier Reef. Live grafts of sponge tissue were fixed onto nine coral species. The sponge was able to invade seven of these nine coral species: Porites australiensis, Porites cylindrica, Porites rus,...

From mid-1997 to late 1998, hard and soft corals in widely separate parts of the world were affected by significant bleaching. Much of this bleaching coincided with a large El Nino event, immediately switching over to a strong La Nina. Scientists and other observers responding to calls for reports from the Global Coral Reef Monitoring Network, and...

The year 1998, was the warmest year since the start of temperature recordings some 150 years ago. Similarly, the 1990s have been the warmest decade recorded. In addition, 1998 saw the strongest El Nino ever recorded. As a consequence of this, very high water temperatures were observed in many parts of the oceans, particularly in the tropical Indian...

Factors causing global degradation of coral reefs are examined briefly as a basis for predicting the likely consequences of increases in these factors. The earlier consensus was that widespread but localized damage from natural factors such as storms, and direct anthropogenic effects such as increased sedimentation, pollution and exploitation, pose...

The phototrophic sponge Phyllospongia lamellosa is found to depths of 30 m on Davies Reef. Studies of the photophysiology show that this corresponds to the depth at which the sponge–symbiont system can meet 80% of its daily respiratory carbon needs photosynthetically. Net 24-h production was constant to a depth of 20 m (20 µmol O2 g-1 fresh weight...

Little is presently known about the role of sponges in bioerosion on the Australian Great Barrier Reef. Porites colonies from three reefs on the Great Barrier Reef (inner-shelf Pandora, mid-shelf Rib and outer-shelf Myrmidon Reef) were examined for evidence of bioerosion with emphasis on sponges. Patterns were found despite relatively low replicati...

Coral reefs have reconstituted themselves after previous large sea‐level variations, and climate changes. For the past 6000 years of unusually stable sea‐level, reefs have grown without serious interruptions. During recent decades, however, new stresses threaten localized devastation of many reefs. A new period of global climate change is occurring...

Coral reefs of SE Asia are both at the center of reef biodiversity, especially the archipelagos of Indonesia and the Philippines, and the focus of rapid economic and population growth. Major stresses are anthropogenic: organic and inorganic pollution, sedimentation and over-exploitation. Many countries have enacted strong legislation to protect cor...

The distribution and photophysiology of two forms of Cymbastela were investigated. One form, which fitted the description of C. notiana, was found in the gulf waters of South Australia. A second form was found on the protected sides of islands along the oceanic coast of Victor Harbor in South Australia. Both forms are rare but when present occur at...

This is a statement of the problem, along with a summary of the method adopted for solving the problem, the major results and conclusions, and an explanation regarding the importance of the research. The Abstract should not include phrases such as “the results will be discussed...”.

Sponge populations on Australia's Great Barrier Reef (GBR) may contain a mix of both phototrophic and heterotrophic species. The distribution of many of these sponges on reefs is assumed to be determined by light. A model was developed to investigate how the distribution of phototrophic sponges over depth is restricted by the availability of photos...

Aerobic heterotrophic bacteria containing bacteriochlorophyll were isolated from specimens from a wide variety of marine environments on the west (Shark Bay, Lake Clifton, Lake Heyward, and Perth) and east (near Townsville and Brisbane) coasts of Australia. The bacteria were found in a high proportion (10 to 30%) of the total heterotrophic bacteria...

Sponge biomass on Belize reefs in the Caribbean is greater than on comparable reefs of the C Great Barrier Reef (GBR), whereas individual abundance and species richness are similar in the 2 regions. Inner-shelf sponge populations are comparable in trophic structure with twice as much biomass and rate of carbon consumption on Belize reefs. With c6 t...

Coral reef sponge populations were surveyed at two spatial scales: different depths and different reef locations across the continental shelf of the central Great Barrier Reef. The surveys were conducted on the forereef slopes of 12 reefs from land-influenced, inner-shelf reefs to those in the oligotrophic waters of the Coral Sea. Few sponges occur...

Sponge populations were surveyed at different depths in three zones of Davies Reef, a large platform reef of the central Great Barrier Reef. Depth is the major discriminatory factor as few sponges are found within the first 10 m depth and maximal populations occur between 15 m and 30 m on fore-reef, lagoon and back-reef slopes. Reef location is ano...

Analyses of fatty acids with carbon numbers between C12 and C22 are reported for five Great Barrier Reef sponges. These analyses indicate that phototrophic cyanobacterial symbionts (blue-green algae) present in three of the sponges are chemically distinct, whereas the other two sponges do not contain cyanobacterial symbionts. All the sponges contai...

Populations of foliose dictyoccratid sponges were surveyed on the forc-rccf (windward) slopes of reefs across the central and northern sections of the Great Barrier Reef. Foliose sponges constitute more than 50 % of invidual abundance on clean water reefs and more than 80 % on some of these reefs. These sponges arc generally small and occur in grea...

Seven species belonging to three genera of foliose Dictyoceratida are described placing emphasis on field recognition characteristics. These sponges are dominant elements of the Great Barrier Reef fauna. One new genus, Strepsichordaia, and two new species, Strepsichordaia lendenfeldi and Carterio-spongia contorta, are described and full redescripti...

Growth rate estimates for five coral reef sponges on the Discovery Bay fore-reef are presented. These were determined from the size of individual sponges growing on the coral rubble that was deposited when Hurricane Allen struck the north coast of Jamaica in August 1980. Sponges collected in February 1986 were weighed and their growth rates determi...

Two coral reef sponges were examined in situ off Puerto Rico for fluxes of dissolved inorganic nitrogen. Chondrilla nucula, a ubiquitous Caribbean sponge with cyanobacterial symbionts, releases large amounts of nitrate (600 nmol N g I (dry wt) h-l; 4,000 Mmol N me2 h-l). Since C. nucula covers a mean of 12% of the substratum, it potentially contrib...

Sponges consume an order of magnitude more organic matter on Caribbean coral reefs than on the Great Barrier Reef. This rate of consumption is attributed to Caribbean sponge biomass being five to six times greater than that on the Great Barrier Reef, on average, and to the absence in the Caribbean of phototrophic sponges, which are a feature of cle...

Large populations of flattened sponges with cyanobacterial symbionts were observed on the shallow reef-flats of the Flinders Reefs, Coral Sea. Estimates of these populations indicated as many as 60 individuals with a total wet biomass of 1.2 kg per m2 in some areas. Along a metre wide transect across 1.3 km of reef flat the population was estimated...

Study of Davies Reef, Great Barrier Reef demonstrated that bacteria are an important link in coral reef food webs. Bacteria reprocess a considerable proportion of reef-produced detritus so that there is c10 times more microbial biomass and productivity in sediments than in the entire water column above the reef. A large and complex fauna occurs on...

Experimental evidence of the transfer of 3H-labelled metabolites from the sponge Ianthella basta Pallas to the epibiont holothuroid Synaptula lamperti Semper demonstrates that the holothuroid gains nutritional advantage from the association by ingesting and assimilating exudates of the sponge. This represents a qualitatively new method of feeding b...

This study was undertaken in 1981 to determine whether there were major variations in potential rates of nitrogen fixation on apparently bare coralline substrate from reefs across the continental shelf of the central Great Barrier Reef. Nitrogen fixation, measured as rates of ethylene production (nmol cm-2h-1), was significantly lower on substrata...

Many marine sponge species contain bacterial symbionts within the intercellular matrix. However, direct evidence on when in the course of evolution these symbioses might have begun is not available. Sponge-specific bacterial strains (296) were isolated from 36 sponge species from the three major sponge classes collected from seven widely separate g...

This study considered whether marine sponges are selective particle feeders, and whether they are capable of distinguishing between sponge bacterial symbionts and other bacteria. Four species of marine sponges (Aplysina aerophoba, A. cavernicola, Pericharax heteroraphis and Spongia sp.) were fed in situ with tritium-labelled bacteria, either symbio...

Nine of the ten most common sponge species on the fore-reef slope of Davies Reef(Great Barrier Reef) contain symbiotic cyanobacteria. Six of the ten are net primary producers, with three times more oxygen produced by photosynthesis than is consumed during respiration. Light interception is enhanced by morphological flattening, thereby increasing th...

In green hydra strains that are bleached by glycerol, photosynthesis is arrested in both intact hydra and freshly extracted algae whereas photosynthesis is not affected by glycerol in resistant hydra strains and their algae. Glycerol sensitivity is an inherent property of the algae and sensitivity can be transferred to resistant aposymbiotic hydra...

Bacteria were isolated from marine sponges from the Mediterranean and the Great Barrier Reef and characterized using numerical taxonomy techniques. A similar sponge-specific bacterial symbiont was found in 9 of 10 sponges examined from both geographic regions. This symbiont occurred in sponges of two classes and seven orders, and it probably has be...

The uptake of tritium labelled proline from the ambiant water by the marine sponge Chondrosia reniformis was studied by electron microscope radioautography. The dissolved amino acid was very fastly incorporated into symbiotic bacteria in the sponge, and more slowly into sponge cells. The ability to use dissolved organic carbon may be important to s...

The marine sponge Neofibularia irata contains four different categories of siliceous spicules. These spicules are evident in the tissues as distinct bundles that act to increase the structural rigidity of the sponge. All spicules have a normal structural morphology with silica deposition around a hexagonal axial canal containing a crystalline axial...

The symbiosis between the freshwater sponge Ephydatia fluviatilis and a chlorella-like green alga is not obligate and only occurs when the sponge grows in the light. The algae accumulate intracellular pools of sucrose and glucose and translocate between 9 and 17% of the total photosynthate to the host. The principal product translocated is glucose...

A bdellovibrio-like bacterium was observed infecting unicellular symbiotic cyanobacteria in two coral reef sponges, Neofibularia irata and Jaspis stellifera. The infecting bacterium, which was located between the cell wall and the cytoplasmic membrane of the cyanobacteria, was similar in size and appearance to previously described bdellovibrios. Th...

NITROGEN FIXATION by endosymbiotic cyanobacteria (blue-green algae) results in an important input of nitrogen into terrestrial ecosystems1; however, there is as yet little information on its significance in the marine environment2,3. Symbiosis of cyanobacteria with marine animals, although rare, is known to occur in an echiuroid worm4 and in sponge...

Transplantation was employed to determine how marine sponges grow in different in situ conditions of light and current. The growth of Verongia aerophoba (Schmidt), which contained symbiotic cyanobacteria. was enhanced in light, particularly when sediment was excluded by a clear shield. V. cavernicola Vacelet and Chondrosia reniformis Nardo. which d...

Scanning electron microscopy was used to examine the form and arrangement of skeletal components in intact specimens of four Great Barrier Reef sponges. The four sponges contain markedly different skeletal components and compositions, typical of the wide genetic diversity in the Porifera. The nature of the sponge skeleton has an influence on the ha...

Three taxonomically distant sponges Pericharax heteroraphis, Jaspis stellifera and Neofibularia irata contain phenotypically similar bacterial symbionts which differ from bacteria in the ambient water. These symbionts are predominant in the sponges and were detected after computer analysis of 526 heterotrophic bacterial strains tested for 76 charac...

Symbiotic cyanobacteria are associated with marine sponges in three ways: the majority are free-living in the mesohyl; large aggregates occur in cyanocytes (specialized, vacuolated archeocytes); and few are present in digestive vacuoles. The cyanobacteria in Jaspis stellifera and Neofibularia irata are morphologically similar to those described in...

Illumination, current strength and physical turbulence influence the distribution of 4 tropical sponges. Three sponges with cyanobacteria in exposed tissues grow only in poen shallow habitats: Pericharax heteroraphis in moderate-current, lowturbulence regions on the reef slope; Jaspis stellifera in low-current, moderate-turbulence regions of the ou...

Coral reefs are complex, biologically diverse, and highly valued ecosystems that are declining worldwide due to climate change and ocean acidification, overfishing, land-based sources of pollution, and other anthropogenic threats. To assist policymakers and resource managers at international, national, and local levels in effectively implementing e...