Neoplasia,regeneration and growth in the reef-building coral Acropora palmata

Abnormal processes of calcification, such as regenerating lesions and neoplasia, situated near the tips(<25 cm) of colonies of Acropora palmata (Lamarck) suppressed normal linear growth. Branches having neoplasia at a larger distance from the tip do not grow significantly differently from controls. This indicates a functional minimal area in terms of energy supply. Neoplasia are pure aragonite and have the same coenosteal structure as regenerative skeletal material. Regeneration of tissue as well as tissue+skeleton lesions involves the simultaneous formation of tissue and regenerative skeleton, trapping foreign material under the regenerated surface. Recovery of a damaged surface slows down with time and this may, in other coral species, result in permanent lesions. A. palmata recovered from all lesions (n=32) within 80 d and appears to be a superior regenerator among Caribbean corals. This is consistent with other life-history characteristics of this highly specialized coral species.     

Studies on reef corals. II. Fine structure of planktonic planula larva of Pocillopora damicornis,with emphasis on the aboral epidermis

Tissue and cellular organization of the planula larva of the reef-coral Pocillopora damicornis are detailed ultrastructurally. Emphasis is placed on fine structure of the aboral (=presumptive calicoblast) epidermis. The pre-settling exploratory behavior of the coral larva is discussed. The aboral epidermis consists of a tall columnar epithelium, made up of a heterogeneous cell population-nematocytes, secretory and mucus cells, and flagellated cells. Basally, the columnar epithelium is modified into complexly interdigitating cellular processes, appearing as a discrete histological layer. A-type granules (Jha and Mackie, 1967) indicate neurosecretory activity. The flagellated cell contains a peculiarly comlex flagellar apparatus, including a new intracellular structure, an electron-opaque fibrous cup. It extends across the entire width of the flagellated cell apically, enveloping the flagellar basal bodies and paired transverse accessory rootlets. The flagellum main basal rootlet passes freely through an opening in the base of the rootlet cup. The flagellated cell is here viewed as a sensory cell, as suggested by the corona of microvilli encircling the flagellum, the bundles of microvilli, and extensive areas of tight junctions with adjacent cells. There is no evidence in the gastrodermis or epidermis of the planktonic larva for pre-settling accumulation of calcareous skeletal material. Vesicles containing a highly oriented fibrous material may represent sites of skeletal organic-matrix precusor buildup.Contribution no. 451. Hawaii Institute of Marine Biology, Kaneohe, Hawaii.     

An electron microscope study on the mineralization of the skeleton of the staghorn coral Acropora hebes

The skeleton formation in the reef-building coral Acropora hebes (Dana) was ultrastructurally investigated by observing the skeletogenic tissue and the skeleton in the apical portion of the branches. The skeletogenic tissue was made of a layer of tall calicoblastic cells which displayed high exocytotic activities. A number of hollow spherules and tiny vesicles were found in the sub-epithelial space between the calicoblastic cell layer and the skeletal plate. These organic materials appeared to occur in the perinuclear Golgi vesicles in the cells. The energy-dispersive X-ray analysis revealed a calcium element in the osmiophilic granules of the calicoblastic cells, but not in any other cell organelles. As the granules showed no diffraction pattern, it was suggested that they could be a Ca-reservoir in the cells. Crystalline particles were found to deposit on the periphery of the sub-epithelial spherules. The spherules developed to spherular crystals by depositing granulated crystalline particles. Two of the spherules appeared to fuse with each other to form a spindle-shaped crystal. The spherular and spindle-shaped crystals accumulated on the thecal ridge and the lateral side surface of the thecal plate, and seemed to contribute to the elongation and thickening of the thecal plate. The thecal plate exhibited a porous structure which probably originated from an aggregation of the central cores of these crystals. On the surface of the thecal plate more than about 5 m thick, scale-like structures composed of spherular crystal substructures were observed. These observations suggest that mineralization in A. hebes occurs in the extracellular space by elabolating the spherular and spindle-shaped precursor structures and that growth of the corallite is brought about by an aggregation and coalescence of these crystals.     

Habitat selection in the tropical polychaeteSpirobranchus giganteus

Total body weight, tube length, abdomen weight and branchial crown weight of individualSpirobranchus giganteus (Pallas) living on four different coral species on the bank reef on the west coast of Barbados were investigated in 1986. Worms onDiploria strigosa were larger in all size parameters than those onMontastrea annularis, which were larger than those onMontastrea cavernosa, which were larger than those onPorites porites. The differences between worms onM. annularis andM. cavernosa were not significant. Variation in worm size on the different corals could result from variation in mortality and/or variation in growth. Whichever the case, larger worms may have higher lifetime reproductive success. Abdomen weight is an index of gamete production inS. giganteus, and increases with increasing body weight for worms on all corals. Moreover, larger worms do not have lower abdomen weight at a given body size than smaller worms. This may imply that faster growth does not reduce gamete production at body size. The coral species on which worms are largest are those most preferred by worm larvae in the laboratory and most heavily colonised by adult worms in the field. The results suggest adaptive habitat selection by planktonic larvae ofS. giganteus.     

Estimation of coral growth-rates from laboratory 45Ca-incorporation rates

Laboratory ⁴⁵Ca-incorporation rates in hermatypic coral skeletons have previously been used successfully as an index of physiological function. This laboratory method would become more meanigful if it also provided an absolute measure of coral growth rates. In two coral species, Porites compressa and Pocillopora damicornis, ⁴⁵Ca incorporation rates were obtained from short (0.5 h) laboratory incubations using apical (determined as fast growing) portions of freshly collected coral branches. ⁴⁵Ca exchange across the coenosarc was not significant and not corrected for, whereas diurnal fluctuation in ⁴⁵Ca in Pocillopora damicornis was significant and a necessary correction. A calculated surface area is used to express calcification rate. Typical growth rates calculated from the ⁴⁵Ca-incorporation rates were 20 and 6 mm/year for Porites compressa and Pocillopora damicornis, respectively. These rates are considerably higher than those previously obtained in the laboratory, and compare favorably with field growth rates — 24 and 14 mm/year, respectively.     

The common mussel Mytilus edulis as an indicator of trace metals in Scandinavian waters. II. lead,iron and manganese

An investigation of the mechanisms of detoxication of copper and zinc by the oyster Ostrea edulis (L) has been carried out using naturally occurring green-sick (contaminated by copper) and unpolluted oysters. Electron microprobe X-ray analysis of tissues in the electron microscope gives direct evidence for the structural compartmentation of copper and zinc in separate, specific, granular amoebocytes. The metals are immobilized in membrane-limited vesicles as different chemical compounds, copper being associated with sulphur and zinc with phosphorus. Chemical analyses of serum and tissues of normal and green-sick oysters indicate that (a) Cu and Zn are accumulated independently, (b) the Cu and Zn in the serum, while higher than in the surrounding sea water, are maintained at a 10-fold smaller level than the tissues, (c) toxicity is reduced by active uptake from the serum into granular amoebocytes, where it is further reduced by compartmentation in membrane-limited vesicles. It is calculated that the individual cell types may contain as much as 13,000 ppm Cu and 25,000 ppm Zn.     

Spatial and temporal patterns of recuruitment of juvenile coral reef fishes to coral habitats within “One Tree Lagoon”, great barrier reef

Recruitment of juvenile fishes to coral grids, each comprising 4 colonies of 3 species of coral (Acropora formosa, Seriatopora hystrix and Pocillopora damicornis), was examined at 4 widely separated sites within the lagoon of One Tree Reef over two successive summers and intervening months (November 1976–January 1978). Recruitment was highly seasonal, with most recruitment occurring during summer. For many species, numbers settling differed greatly from year to year with total numbers (over all sites) differing as much as an order of magnitude between summers. Many fish species demonstrated marked preference among the three coral species as settling sites. The distribution of each of the 20 commonest species across the 4 lagoon sites differed significantly from a random pattern. Differences of an order of magnitude were common in the numbers of a given species recruited to different sites. Each site was preferred by at least one species. In each of 5 cases examined, the pattern of settlement of the species across the 4 sites changed significantly from one summer to the next. The distribution of recruits of a number of species corresponded to the distribution of adults, but for other species there was no correspondence. It is concluded that, at the spatial scale examined, patterns of recruitment of some taxa are consistently more variable than those of other taxa. The implications of spatial variability of recruitment for the distribution of adult fish is discussed and the importance of being able to discriminate such natural variability from other kinds of change is stressed.     

The biology of colonial hydroids. II. The morphology and ultrastructure of the medusa of Eirene viridula (Thecata-Leptomedusa: Campanulinidae)

The free-swimming medusae of Eirene viridula are typical marine hydroids, with distinct subdivisions into body regions, which were studied by comparison of light and electron microscopy. Particular attention is given to the epithelio-muscular and digestive muscle cells. The epidermis — apart from a few nerve cells and cnidocytes-consists of epitheliomuscular cells. At their bases these cells form a musculature and at the apex many secretory vesicles. In the velum, large expansions of the intercellular space are found. The gastrodermis — apart from the mucous and zymogen cells in the manubrium — consists of digestive muscle cells, the structure of which corresponds in principle to that of the epitheliomuscular cells. In its apex, this type of cells contains both normal coated vesicles and discoidal coated vesicles. In the solid tentacles, the digestive muscle cells form a turgescent vesicular tissue. The central nervous system consists of the exumbrellar, subumbrellar, and gastrodermal nerve rings. They are composed of ganglion cells, their processes, and intraepithelial flagella. The static organs are purely ectodermal statocysts which have only one lithocyte and only one sensory cell.     

Reducing the environmental impact of coal-washing practice in Australia

All Australian coal for export is washed — that is, the low-grade high-ash material is separated out and disposed of at the washery site. The coarse rejects are generally placed in embankments and the tailings are pumped into settling ponds. These methods of waste disposal can create environmental problems. In addition, they represent a significant energy loss, because about one-third of the waste material is combustible and is thus a potentially valuable source of energy. Laboratory studies at the CSIRO Division of Fossil Fuels at North Ryde, New South Wales, have shown that energy can be successfully recovered from washery wastes by the process of fluidized-bed combustion. A pilot fluidized-bed combustor, with a capacity of 2 tonnes/hour, is undergoing prolonged trial at the Clutha washery near Camden, New South Wales, in a joint project between the Joint Coal Board and CSIRO. The results from the pilot plant tests have provided the basis for a conceptual design and feasibility study for a full-scale tailings treatment plant. This study has indicated that fluidized-bed combustion:

1. offers an environmentally attractive and economically competitive alternative to the disposal of tailings in settling ponds, and
2. can be used to generate large quantities of energy from the wastes, reducing the energy lost in coal washing from around 16% to 6% of the coal mined.

     

Detrital pathways in a coral reef lagoon

Coral reef lagoons are generally regarded as zones of net heterotrophy reliant on organic detritus generated in more productive parts of the reef system, such as the seaward reef flat. The abundance and biomass of sediment infauna were measured seasonally for one year (1986) within the lagoon of Davies Reef, central Great Barrier Reef, to test the hypothesis that macrofaunal biomass and production of coral reef lagoons would decrease with distance from the reef flat and would change seasonally. In general, there were no simple relationships between infaunal standing stock or production and distance from the reef flat or season. Bioturbation by callianassid shrimps negatively affected the abundance of smaller infauna, suggesting a community limited by biogenic disturbance rather than by supply of organic material. Polychaetes and crustaceans were dominant amongst the smaller infauna (0.5 to 2mm) while larger animals (> 2 mm) were mostly polychaetes and molluscs. Mean biomass of infauna at both sites and all seasons was 3 181 mg C m^?2. The smaller animals (0.5 to 2 mm) contributed about 40% of total macrofaunal respiration and production although they represented only 15% of the total macrofaunal biomass. The biomass of macrofauna was about equal to that of the bacteria and meiofauna, while respiration represented 10 to 20% of total community respiration. Consumption by macrofauna accounts for only 3 to 11% of total organic inputs to sediment, with a further 14 to 17% being lost by macrofaunal respiration.     

The role of metabolic nitrogen in coral calcification

When pieces of the staghorn coral Acropora acuminata are incubated with ¹⁴C-urea, the label is incorporated into skeletal carbonate. Incorporation of this label differs from that of H¹⁴CO ₃ ^- , suggesting urea is not immediately hydrolysed to provide a further source of HCO ₃ ^- . The effects of certain organic substrates upon calcification suggest the ornithine cycle is involved. Citrulline, an ornithine cycle intermediate, is found in high concentrations in the tissues of hermatypic corals. Urea, allantoins, NH₃ and arginine are also present. These compounds are barely detectable in zooxanthellae or an ahermatypic coral. The allantoins may be present as calcium salts. It is suggested that allantoins are the medium by which Ca²⁺ and CO₂ are transported to sites of calcification. Hydrolysis of urea, formed by breakdown of allantoins, yields CO₂ and NH₃. The NH₃ may neutralise protons formed during precipitation of CaCO₃ and bring about their removal from sites of calcification. As well as providing urea, the ornithine cycle may also be involved in the removal of NH₃ from sites of calcification.     

Pit structure and trophic relationship of the coral pit crab Cryptochirus coralliodytes

Individuals of the pit crabs Cryptochirus coralliodytes Heller inhabit massive corals of the family Faviidae. Their pit walls were observed to be covered by blue-green algae and fungi. We suggest that the crabs enhance the growth of these algae and fungi with their metabolic excretions, which contain ammonium. The endolithic algae and the fungi may facilitate the abrasion of the coral skeleton by the crabs, by perforating it and thus weakening the skeletal structure. Computerized tomography analysis revealed dense skeletal material around the pits. Transverse sections showed that the calcification around the pit was similar to other parts of the colony, whereas the macro-architecture was different. Such a difference is the result of the crabs' influence on the corals' living tissue, possibly on the calicoblast which deposits the coenosteum. Crabs, which were exposed to carbon-labeled corals for 1, 7 and 18 d, accumulated labeled carbon, indicating transfer of carbon from the coral tissue to the crabs. Histochemical examination of the stomach and gut of crabs revealed the presence of mucopolysaccharids in the gut, supporting the hypothesis that the crabs eat coral products. The findings of this study provide additional evidence that C. coralliodytes are parasites and support the general hypothesis that a nutritional relationship may have served as a basis for selection. Received: 20 October 1998 / Accepted: 29 April 1999     

Exceptionally high concentrations of the insect repellent N,N-diethyl-m-toluamide (DEET) in surface waters from Jakarta,Indonesia

Jakarta is a booming coastal megacity in Indonesia with over 10 million inhabitants. The rivers flowing through the city district receive enormous amounts of untreated wastewaters from households and industries and discharge high pollutant loads into Jakarta Bay. Applying a screening approach for the identification of characteristic site-specific and harmful organic contaminants, we frequently found the insect repellent N,N-diethyl-m-toluamide (DEET) in river water and seawater samples from Jakarta. The compound was previously reported as persistent aquatic contaminant in industrial countries, and we present here the first data set from a tropical megacity. Concentrations in river water and seawater from Jakarta were exceptionally high, up to 24,000 ng L^?1, and exceeded by far all published concentrations in surface waters worldwide. We explained this with massive usage of the compound, lack of wastewater treatment and low average river flow as compared to rivers in other tropical megacities. The usage and properties of DEET indicate its suitability as molecular marker of municipal wastewaters. Such markers are useful to trace emissions from specific pollution sources in aquatic systems as a basis for the investigation of related impacts. We show here that DEET is in particular useful to trace the long-range distribution of municipal wastewaters in tropical freshwater and coastal systems. This application is of great value for tracing such inputs in tropical coastal habitats which are sensitive to changing water quality like coral reefs. This assists to uncover whether specific conditions in these systems could be related to pollutant inputs from land.     

Studies on reef corals. I. Skeleton formation by newly settled planula larva of Pocillopora damicornis

Initiation of coral-skeleton formation was studied in the reef-coral Pocillopora damicornis Lamarck. Observations were made on sequential skeletal growth stages of newly settled planula larvae during the first 22 days following settling onto glass microscope slides. Techniques used include phase light microscopy, scanning and transmission electron microscopy, and powder X-ray and selected area electron micro-diffraction. Formation of the skeleton is initiated immediately on settling of the larva. The primary calcareous elements are of two types — flattened spherulitic platelets, and smaller rod-like granules. Rudimentary primary septa are clearly defined within 6 h after settling. Fusion of the primary calcareous elements results in the formation of the larval basal disc within 48 to 72 h. With transmission electron microscopy, this basal disc is found to differ from subsequent adult calcification in (1) considerably lesser degree of mineralization, (2) smaller crystal size, (3) more random orientation of the crystals, and (4) the presence of trace amounts of calcite in addition to aragonite. The basal disc with its septal rudiments constitutes a true larval skeleton, differing in morphology, micro-architecture, and crystal type from the fibrous growth characterizing the adult skeleton.Contribution 419, Hawaii Institute of Marine Biology, University of Hawaii.     

Enhanced organic phosphorus detection in sediments by foam separation and 31P-NMR

Phosphorus (P) is both a nutrient and a pollutant. For instance, excess P induces water eutrophication followed by death of fishes and other water life. Determination of organic P content in sediments is therefore important to study P cycling and environmental pollution. The most widely used method to determine organic P in sediments is NaOH–EDTA extraction followed by ³¹P-NMR detection. However, some organic P compounds are difficult to extract using NaOH–EDTA due to the low solubility, thus can not be detected by ³¹P NMR. Here, we used foam separation to determine organic P in sediment of North Canal of Tianjin City, China. Organic P was first enriched using foam separation coupled with NaOH extraction. The enriched organic P was then analyzed with ³¹P NMR. The results showed that, compared with the traditional extraction method, foam separation coupled with NaOH extraction enriched more P compound because ³¹P NMR detected an extra signal of teichoic acid at chemical shift 1.14. This teichoic acid signal was not detected in the extract prepared using only NaOH–EDTA. Our finding demonstrates that determination using foam separation followed by ³¹P NMR is feasible.     

Growth and form in the reef-building coral Montastrea annularis

The in-situ growth rate of the reef coral Montastrea annularis on a reef at Jamaica, W. Indies was determined for a 1-year period using Alizarin Red-S staining techniques. Growth rate is correlated with water depth and growth form. The flattened growth form of M. annularis allows for continued rapid increase in colony surface area at low light intensities. The geomorphology of Jamaican reefs may in part be controlled by the population ecology of M. annularis.     

Effects of gamma-aminobutyric acid on the settlement of larvae of the black chiton Katharina tunicata

Laboratory-cultured larvae of the black chiton Katharina tunicata (Wood), collected from central California in May and June of 1979 and 1980, settled preferentially on the encrusting coralline alga Lithothamnium sp. Metamorphosis, which involves the loss of the prototrochal ciliary band, occurred within a period of 2.5 h after larvae began crawling upon the alga. In response to gamma-aminobutyric acid (GABA) at a concentration of 10^-6 M, the lecithotrophic trochophore larvae ceased swimming and settled rapidly. Developmental metamorphosis did not follow settlement in the absence of encrusting coralline alga. However, when both GABA and Lithothamnium sp. were present, larval metamorphosis occurred within 2 h of settlement. Significantly different rates of settlement exist for sibling larvae of different ages; 12 d-old larvae responded more rapily and in greater numbers to treatment with GABA than 10 d-old larvae. Differences in settling rates are attributed to the onset of metamorphic competence.     

Assimilation,inter-organ transfer and excretion of americium in two teleost fish

Radiotracer experiments were performed (February–April, 1982) to study the assimilation and metabolism of the transuranium nuclide americium-241 in the marine teleosts Serranus scriba (Linnaeus, 1758) and Scorpaena notata Rafinesque, 1810, caught off the Monaco coast. Fish fed with ²⁴¹Am-labelled food showed that assimilation of this radionuclide takes place through the gastrointestinal walls and that the small fraction accumulated is incorporated mainly in the skin, muscle and skeleton. Gut-transfer coefficients were similar in both species and averaged 0.7% (range 0.1 to 1.7%) of the ingested activity. The calculated biological half-lives for loss of the absorbed fraction ranged between 49 and 61 d for Serranus scriba and 12 and 117 d for Scorpaena notata. Results from an intramuscular injection experiment indicated that ²⁴¹Am was retained mainly in the liver, skin and skeleton; the fraction accumulated by muscle was very low. Liver displayed a relatively short biological half-time for ²⁴¹Am loss of roughly 24 d. Routes of ²⁴¹Am excretion from the teleosts appear to be through the kidneys, gills and feces with bile serving as a possible excretion route from the liver. From the limited amount of published information available for comparison, experimental evidence is presented which suggests that ²⁴¹Am taken up via the food chain is more biologically available to marine fish than is plutonium.     

Fungi in corals: black bands and density-banding of Porites lutea and P. lobata skeleton

 Dark coloration of coral skeleton forming black bands is commonly observed in fractured, massive-coral colonies (Porites lutea and P. lobata) collected from May- otte Island in the Mozambique Channel and Moorea Island in French Polynesia. Black-banding was similar in corals from the two areas and was associated with an assemblage of microbial endoliths: Ostreobium queketti, a common siphonal chlorophyte, and a type of Aspergillus-like fungus. Fungi of coral skeletons are capable of euendolithic growth entirely within the skeleton, and of cryptoendolithic growth whereby they spread from the skeleton into the skeletal pores. The morphology and size of fungal hyphae differs significantly between euendolithic, cryptoendolithic and reproductive phases. Reproductive phases involve formation of conidiophores. Insoluble residues in black bands involve a dark pigment and a dark membranous veil. When attacked by fungi, the algae are usually destroyed. They darken and are threaded by dense, dark-brown, fibrous excrescences. The fungi excrete a dark pigment that stains the surrounding skeletal carbonate black. The pigment is organic, and its presence correlates with higher concentrations of polysaccharides. Black bands match high-density bands of the coral skeleton. Both black bands and high-density bands form at the end of the rainy season in Mayotte. Thus, black-banding in the corals studied is caused by a series of events, beginning with an increase in the abundance of endolithic algae followed by an increase in skeletal density. The algae are then attacked by fungi, which produce more cryptoendolithic hyphae and conidia that are associated with production of the dark pigment. Received: 29 January 1999 / Accepted: 29 September 1999