Coral Reef Waters Research Articles

The important role of organic matter cycling for the biological fixation of CO 2 in coral reefs

The role of organic matter cycling in increasing biological fixation of CO 2 in coral reef has been studied at Miyako Island in Japan (RITE project of coral reef study). The carbon and nitrogen contents of dissolved and particulate forms of organic matter in coral reef water and in various living organisms were measured. It was found that the concentrations of dissolved and particulate organic matter in the reef are lower than those of open ocean, despite of higher gross productivity area in the world ocean. Calculation from the temporal changes of organic carbon and inorganic carbon in the water column revealed that there is an imbalance between production and consumption. This suggets that carbon accumulates as organic matter in living organisms and the benthic floor of coral reef.

Sphaeromatidae From the Watamu Area, Kenya Description of a New Genus and Four New Species (Isopoda, Flabellifera)

AbstractThe present contribution on sphaeromatid isopods from shallow water coral reef locations in Kenya reports on four new species in the genera Afrocerceis n.gen., Paracilicea Stebbing, 1910 and Paradella Harrison & Holdich, 1982. They are described in detail, with remarks on their inter-specific affinities, habitat preference and biogeography. A description is further provided for Dynamenella scaptocephala Messana, 1990. Paracassidinopsis perlata (Roman, 1974) is first recorded from the African continent.

Cirolanidae (Isopoda) From French Polynesian Coral Reefs: Description of Three New Species

AbstractThis first contribution on cirolanid isopods from shallow water coral reef locations in French Polynesia (Bora Bora, Moorea) reports on three new species of the genera Cirolana and Metacirolana. They are described in detail, with remarks on their intergeneric affinities, habitat preference and biogeography.

Comparison of DNA and protein synthesis rates of bacterial assemblages between coral reef waters and pelagic waters in tropical ocean

Comparison of DNA and protein synthesis rates of bacterial assemblages between coral reef waters and pelagic waters in tropical ocean

Status of eutrophication in the Great Barrier Reef lagoon

Historical data on the levels of nutrients and phytoplankton in the GBR lagoon are reviewed. The results indicate that background levels of P-PO 4 and phytoplankton have increased significantly over the past 50–60 years and that the levels appear be at or above the eutrophication threshold level for coral reef waters. Other data indicate that river discharge probably has a major impact on the nutrient status of the GBR lagoon, but other factors such the nitrogen-fixing blue-green alga, Trichodesmium, could also be important. Trichodesmium has the ability to introduce large amounts of new nitrogen and it appears that the increased phosphorus levels could be driving its growth. To-date little effort has been made to assess the impact of eutrophication on the coral reef communities. Because the background nutrient levels are relatively high both run-off and sewage discharges could have serious impacts on nearby coral reef communities. Tertiary treatment (i.e. nutrient removal) of sewage should be required for all discharges in the vicinity of coral reefs and special precautions need to be exercised when designing run-off drainage systems.

Phosphorus metabolism in Coral Reef Communities: Dynamics in the Water Column

Phosphorus dynamics were studied in the coral reef waters of Heron and Wistari Reefs in the Capricornia group, Great Barrier Reef, Australia, using radioisotopic techniques. All studies were made during August-October 1986. Labelled phosphate (PO4 -33P) was used to measure total uptake as well as uptake by bacterioplankton alone. Rates of total PO4-P uptake by microplankton varied between 20 and 120 ng P L-1 h-1 at water temperatures of 20-24� C. The daily (24 h) uptake rate of PO4-P was 0.5-3.0 �g L-1. The ambient PO4-P content of water over the reefs was low (0.03- 0.3 �mol L-1, or 1-10 �g P L-1). Turnover time of PO4-P in the water column of these reef areas is therefore very short, being in the range of 2-8 days, even when its possible net consumption by bottom biota is ignored. Bacterioplankton, not phytoplankton, was found to be the major consumer of inorganic phosphorus in these waters. The percentage of total PO4-P uptake by bacteria varied from 50 to 90%. The results of these estimations are discussed in terms of the importance of active phosphorus dynamics in the water column to the nutrient budget of the coral reef ecosystem.

Biomass and photosynthetic activity of phototrophic picoplankton in coral reef waters (Moorea Island, French Polynesia)

In April 1984, chlorophyll a and photosynthetic activity of phytoplankton were measured above a coral reef and in the deep chlorophyll maximum (100m) of adjacent oligotrophic oceanic waters. Samples were frachonated into 3 sizes: 0.2-2. 2-5 and 2 5 km. Total chlorophyll a concentrahons were about 0.1 mg m-3, and phytoplankton > 5 pm never exceeded 104 cells I-'; picoplankton were not enumerated. Reef samples differed from oceanic waters by containing higher proportions of diatoms and lower proportions of coccolithophorids Chlorophyll biomass was dominated by the 20 mg C mg chl-' h-') occurred in the < 2 m subsequent grazing of small cells by corals and other constituents of the food web ('picoplankton loop'), may contribute to nutrient cycling within the reef ecosystem.

Mise au point sur les Scléractiniaires comme indicateurs de profondeur (Cnidaria : Anthozoa)

Review of the Scleractians as depth indicators (Cnidaria : Anthozoa). Before considering the use of fossil scleractinians as depth indicators, their living counterparts are presented in their morphological and ecological diversity. Jointly, the main environmental factors conditioning their geographical and depth distribution are pointed out. Intraspecific variation depending on environmental factors makes taxonomy of the group more complicate. Taxonomy is yet far from being satisfactory for many taxa, particularly in some areas. The terms hermatypic-ahermatypic as currently used by biologists and geologists, are not without ambiguities due to the original definition (WELLS, 1933) ; they are discussed together with complementary terms, which had been introduced in order to remedy to that ambiguity. In case of precise taxonomy and well recorded ecology, reference to living scleractinians permits extrapolation of paleoenviron-ments corresponding to fossil assemblages. It is important to distinguish between shallow water coral reefs of the tropical type and scleractinian constructions in deep water ; characters useful for this distinction are indicated. But the present contribution more specifically aims at demonstrating the usefulness of non-reefal scleractinians as indicators of depth (and temperature). According to WELLS (1967), the depth (and temperature) interval in common to the taxa present in a fossil assemblage can be estimated by reference to identical or related living forms. This provides an approximation for the paleoenvironment under analysis. It is essential to detect an eventual mixture of faunas issued from significantly different depth levels in order to avoid the pitfall of averaging incomparable data. At least for assemblages of a rather young geological past, extrapolations can be remarkably precise (examples of Pleistocene faunas from the Mediterranean). Howewer, the more remote in age the assemblages are, the less precise will be the results because more and more taxons in common with the Recent drop out. Analysis of morphofunctional adaptations, detached from any taxonomie basis, will provide, at best, only general information on the type of the'environment (deep or shallow) and of the substrate (soft or hard, stable or unstable).

In situ culturing of larvae of the crown-of-thorns starfish Acanthaster planci

In situ culturing of larvae of the crown-of-thorns starfish Acanthaster planci

Analysis of Hull Remains, Ballast, and Artifact Distribution of a 16th-Century Shipwreck, Molasses Reef, British West Indies

AbstractIt has often been said that ships wrecked on coral reefs in shallow tropical water seldom preserve their archaeological integrity: that the wood of the hull is not sufficiently well-preserved to warrant study, that smaller iron artifacts invariably are in poor condition, that ballast of such wrecks has no archaeological significance, and that surviving components of these sites are frequently re-sorted and further degraded with each passing storm to the extent that artifact distributions are rendered senseless. This “conventional wisdom” that all shipwrecks are in “marine peril” and must be salvaged as soon as possible has supplied a pretext under which untold numbers of Caribbean shipwreck sites have been obliterated.Results from three seasons of excavation on a 16th-century shipwreck on Molasses Reef in the Turks and Caicos Islands, British West Indies, indicate that this loss of integrity is not always the case. Field methods for recording distributions of components within the site are describ...

The pontoniine shrimp fauna of Australia

The caridean family Palaemonidae Samouelle consists of two major subfamilies. The Palaemoninae are conspicuous in tropical freshwater and temperate marine habitats and are almost entirely free-living. The Pontoniinae are almost exclusively tropical and subtropical marine commensals and are rarely found in temperate or fresh waters. They occur most abundantly in the warm shallow waters of tropical coral reefs and the species probably present in deeper waters here have so far been little studied. The use of scuba-diving as a collecting method in recent years has greatly increased the efficiency of sampling coral reefs and other shallow water marine animals. Precise information can now be obtained for many species with regard to their habitats or associations. Many of the more cryptic species could not be reliably collected by any earlier method and so remained 'rare' and little known. Coral reefs are famous for the diversity of the fauna that they support, and the Great Barrier Reef and the caridean shrimps are no exception to this generalisation. Among the marine shrimps in Australian seas only the snapping shrimps of the family Alpheidae exceed the number of species of the subfamily Pontoniinae. ...

Particulate Organic Carbon of Bottom Boundary and Submarine Cavern Waters of Tropical Coral Reefs

Particulate Organic Carbon of Bottom Boundary and Submarine Cavern Waters of Tropical Coral Reefs

Deep-sea ahermatypic scleractinian corals: isotopic composition of the skeleton

13C/ 12C and 18O/ 16O ratios of the skeletal aragonite deposited by ahermatypic scleractinian corals were measured for 220 separate specimens taken from marine environments ranging from deep-sea and/or cold water habitats to the warm waters of tropical coral reefs. Each sample is depleted in 13C and 18O relative to calcium carbonate in isotopic equilibrium with the ambient sea water system. Despite apparent isotopic disequilibrium, systematic relationships between isotopic composition and environmental parameters are clearly apparent, permitting the use of stable isotope ratio data for non-reef-building corals in paleoecological and paleoenvironmental interpretations if certain precautions are taken. Skeletal δ 18O and water temperature are closely related for the ahermatypes over the entire temperature range of present-day oceans (∼ 0–30°C). The temperature versus δ 18O curve is parallel to that for CaCO 3 in oxygen isotopic equilibrium with sea water, but it is displaced 2·4 per mil towards lower δ 18O. These findings have implications concerning the mechanism of calcification in the scleractinian corals. Oxygen isotope ratios recorded in the skeletons of deep-sea ahermatypes may be utilized as geochemical indicators of temperature and/or depth.

PRODUCTION OF PARTICULATE ORGANIC MATTER BY THE REEF ON KAVARATTI ATOLL (LACCADIVES)

The concentration of particulate organic carbon in the vicinity of Kavaratti Atoll is much greater than that of the surrounding sea. The particulate organic matter, which is largely produced by the coral reef, amounts to about 20% of the total gross production of the reef community. It is suggested that, in the absence of an adequate standing crop of phytoplankton, the particulate matter may form an important source of energy to zooplankton in coral reef waters.

Terrigenous sedimentation in a shallow water coral reef environment

ABSTRACT Van Veen grab samples were examined to study the environment and history of deposition associated with the coral reefs at Anton Lizardo, Mexico. These are Recent reefs growing on a shallow marine shelf which was emergent until 9,000 to 10,000 years ago. There are eight larger reef structures which rise from depths of less than 25 fathoms. The reefs are elongate and parallel to the shoreline. Although there is some carbonate material in the inter-reef sediments, most of the sediment cover is terrigeneous sand and gravel. Most of these sediments appear to be pre-Wisconsin in age. They were probably deposited while the area was exposed to subaerial processes. The post-Wisconsin coral reefs contribute only a small part of the sedimentary cover, and present deposition from the Rio Jamapa appears to be minor.