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1.
Three methods of evaluating stony coral communities were used on selected reefs in the Exuma Cays Land and Sea Park (24°22N, 77°30W) in the central Bahamas. Shallow reefs (< 4 meters depth) were selected from aerial surveys based on size, location, and physical setting, and grouped into three community types: (1) channel patch reefs, (2) soft-coral-sponge patch reefs and (3) fringing reefs. Three survey techniques used to evaluate the stony coral communities were a) species presence and absence lists, b) linear percentage and c) line transects using 1 mx1 m grids. Data collected from these survey methods was used to calculate coral colony density, species area coverage, and species diversity based on colony number and based on linear (cm) coral cover. The linear percentage sampling was considered too convervative in determining distribution patterns of a reef community; this technique takes into account the massive reef framework species such asM. annularis. The line transect technique can account for both colony number and area coverage, thus is a better method for characterizing reef communities. Sample size considerations are discussed for future applications of survey techniques for ground-truthing digital images of small, shallow reef communities.  相似文献   

2.
The degradation rate of the D1 polypeptide was measured in threeSynechocystis PCC 6803 mutantsin vivo. Mutations were introduced into a putative cleavage area of the D1 polypeptide (QEEET motif) and into the PEST-like area. PEST sequences are often found in proteins with a high turnover rate. The QEEET-motif mutants are CA1 [(E242-E244);Q241H] and E243K, and the third mutation, E229D, was directed to the PEST-like area. During high-light illumination (1500 mol photons m-2s-1) that induced photoinhibition of photosystem II (PSII), the half-life time of the D1 polypeptide in mutant E229D (t 1/2=35 min) was about twice as long as in AR (control strain) cells (t 1/2=19 min). In growth light (40 mol photons m-2s-1), the degradation rate of the D1 polypeptide in E229D and AR strains was the same (t 1/25 h). In growth light the D1 polypeptide was degraded faster in both QEEET-motif mutants than in the AR strain, but in photoinhibitory light the degradation rates were similar. According to these results, the highly conservative QEEET motif as such is not required for the proteolytic cut of the D1 polypeptide, but it does affect the rate of degradation. No simple correlation existed between the degradation rate of the D1 polypeptide and the susceptibility of PSII to photoinhibition in mutant and AR cells under our experimental conditions.  相似文献   

3.
Three species of the reef coral genus Madracis display skeletal isotopic characteristics that relate to depth, colony topography, and consequently to coral physiology. The joint interpretation of skeletal 13C and 18O provides information on the ecological plasticity and adaptation to depth of a coral species. Isotopic results are most easily understood in terms of kinetic effects, which reduce both 18O and 13C below isotopic equilibrium values, and metabolic effects, which only influence the skeletal 13C. Madracis mirabilis is adapted to depths shallower than 20 m, and shows the greatest range in kinetic effects and the strongest metabolic 13C enrichments caused by symbiont photosynthesis. Madracis formosa lives deeper than 40 m, and shows a reduced range of kinetic effects and relatively weak metabolic 13C enrichments. Madracis pharensis inhabits depths from 5 to >60 m, and does not attain the strength of kinetic effects of either of the other two species, apparently because it is not quite as well adapted to rapid growth at either extreme.  相似文献   

4.
It has been reported, recently that an aqueous extract from hollyhock flowers (Althaea rosea Cav. varietas nigra) induces weak metabolic changes in rat testes. In the present study, the in vivoinfluence of a methanolic extract was investigated on the metabolism and morphology of the rat testis. To this end, histochemical, morphometric and radioimmunological methods were used. The rats drank the extract at a dose of 100mg/day for 7weeks. The histochemical activities of glucose-6-phosphate dehydrogenase (G6PDH) and 5-hydroxysteroid dehydrogenase (5HSD) increased significantly statistically in the Leydig cells of the experimental rats in comparison with controls. There were no significant changes in either the diameter of seminiferous tubules or the height of seminiferous epithelium after hollyhock administration. Further, only a small amount of hyperplasia of the interstitial tissue was observed. The morphological and histoenzymatic changes in the Leydig cells indicate that the methanolic hollyhock extract has a direct but small influence on rat testes. The insignificant changes in testicular testosterone and estradiol content suggest that the extract does not disturb steroidogenesis.  相似文献   

5.
X-radiography and carbon and oxygen stable isotope analysis have been used to examine the effects of prolonged bleaching on the growth rate and chemical composition of the skeleton of the massive reef coral, Montastrea annularis. The post-bleaching linear growth of one colony that remained bleached for 10 to 12 months following the 1987 Caribbean-wide bleaching event was only 37% of mean annual growth from pre-bleaching years, and was manifest as a loss of the following year's low density band. Two colonies that did not bleach (normal) and two that bleached and regained their coloration (recovered) had linear growth rates over the same period that were 81 to 98% of mean pre-bleaching annual growth. Linear growth by a third recovered coral was 66% of pre-bleaching growth. No sub-annual stress bands were associated with the bleaching. The skeleton of the bleached colony had carbon and oxygen isotopic compositions that were reduced in range and enriched (increased) in both 13C and 18O in the post-bleaching year. The skeletons of two of the nine colonies, one bleached and one recovered, had depleted (reduced) 18O values (-5.3 and -4.8%., respectively) during the bleaching episode that agree with the suggestion that positive temperature anomalies occurred during, and may have caused, the bleaching event. The range and values for all other normal and recovered corals, however, were not different between the post-bleaching year and previous years. Our data suggest that stress bands and isotopic analysis of coral skeletons may not always be reliable tools for examining the occurrence, cause or effects of certain discrete stress events that may interrupt skeletal growth.  相似文献   

6.
Summary One system of monomeric adenylate kinase isozymes, designated ADK, was observed in Triticum aestivum and in five diploid Triticeae species. The gene loci Adk-a, Adk-b and Adk-d were located on 7AL, 7BL and 7DL Triticum aestivum cv Chinese Spring chromosomal arms, respectively. Adk gene loci were also located on the 7RL chromosomal arm of Secale cereale cv Ailés, the 7H chromosome of Hordeum vulgare cv Betzes, 7X of Agropyron intermedium, 7E of Elytrigia elongata and CSU-E of Aegilops umbellulata. The results suport the notion of the conservation of gene synteny groups within Triticeae species.  相似文献   

7.
Unlike most marine teleosts, the coral reef-dwelling spiny damsel, Acanthochromis polyacanthus, lacks a pelagic larva dispersal phase and represents one of few examples of self recruitment onto a natal reef by a marine teleost immediately after hatching. Benthic eggs are protected by the parents, and upon hatching the young remain under parental care for several months. Visual morphogenesis of spiny damsel embryos and juveniles was examined to evaluate the potential visual capabilities of the young after emergence onto the reef. The optic primordia were visible in the embryo as hollow spheres of undifferentiated neuroblasts 2 days after fertilization (daf). Visual morphogenesis proceeded rapidly thereafter in the embryo such that at hatching (between 10 and 12daf) gross visual morphology was consistent with that reported in the majority of juvenile marine teleosts, reflecting direct development of the retina of the spiny damsel within the egg. At hatching, the outer nuclear layer comprised 2 classes of photoreceptors; cones and rods. Tangential sections of the retina revealed a square cone mosaic in which 4 double cones surrounded a single cone. This arrangement remained unchanged in all later life history intervals examined. Absolute eye size was large compared to larvae of marine pelagic spawners. Eye and lens diameters increased from 0.69 and 0.23mm, respectively, on the day of hatching (12daf), to 3.77 and 1.52mm, respectively, in a fish 131daf. Angular density of cones increased from 0.25 cones 10 visual arc–1 in an embryo 8daf, to 1.14 cones 10 visual arc–1 in a fish 131daf, demonstrating the potential for significant increase in spatial resolution with increasing eye size. Convergence ratios of cones to ganglion cells remained relatively constant from the time of hatching, suggesting that the determinate ganglion cell photopic receptive field was established early in development. The increase in the convergence ratios of rods: ganglion cells from 1.4 in the late stages of embryogenesis (10daf; 2 days prior to hatching) to 4.9 in a fish 103daf, demonstrated increasing scotopic ganglion cell receptive field size, with increasing age. This was a result of rod cell addition with growth. An increase in the angular density of rods from 0.18 rods 10 visual arc–1 in an embryo 8daf, to 4.07 rods 10 visual arc–1 in a fish 131daf, and the increase in mean scotopic light path-length from 13.3±1.1m in an embryo 8dpf, to 55±5.2m a fish 22dpf, collectively indicate the potential for increasing scotopic sensitivity during growth. On the basis of visual morphology it is predicted that newly hatched spiny damsel juveniles have substantially greater visual capabilities than first feeding larvae with a pelagic dispersal phase. In addition, we propose that the developmental trajectory of the spiny damsel is different from that of pelagic dispersing larvae and does not simply reflect displacement along a common developmental continuum by an extended embryonic duration.  相似文献   

8.
Line transects were used to sample the structure and diversity of the hermatypic coral community (Scleractinia) on four shallow shelf-edge reefs in South Florida (25° 22N to 25° 29N). Low diversities, cover and abundance indicated that this area was a suboptimum habitat for reef-building corals. The lack of acroporids on the shallow fore-reef, the increase in total coral cover with depth and the greater abundance of Montastrea annularis in the deepest zones suggests that cooling of surface water during severe winter cold fronts is a major environmental control on the distribution of hermatypic corals with depth. Such disturbances, occurring more frequently than hurricanes, may preclude the hard-coral community from attaining higher levels of cover and abundance. The shallow zones on the reefs nearest to tidal passes, through which cooled by water enters the reef tract, had the least developed community. In the deeper reef-zones, species richness and abundance increased from north to south over a distance of 13 km.  相似文献   

9.
The dynamics of benthic microbial communities were examined within different functional zones (reef crest, reef flat, lagoon) of Davies Reef, central Great Barrier Reef, in winter. Bacterial numbers did not change significantly across the reef with a mean abundance of 1.3 (±0.6) x 109 cells g-1 DW of sediment. Bacterial production, measured as thymidine incorporation into DNA, ranged from 1.2 (±0.2) to 11.6 (±1.5) mg C m-2h-1 across the reef and was significantly lower in a reef crest basin than in the other zones. Bacterial growth rates () across the reef (0.05 to 0.33 g-1) correlated only with sediment organic carbon and nitrogen. Protozoan and meiofaunal densities varied by an order of magnitude across the reef and correlated with one or more sediment variables but not with bacterial numbers or growth rates. Nutrient flux rates were similar to those found at other reefs in the central and southern Great Barrier Reef and are significantly lower than rates measured in temperate sand communities. In the front lagoon, bioturbation and feeding acitivity by thalassinid shrimps (Callianassa spp.) negatively influenced microbial and meiofaunal communities with a net import of organic matter necessary to support the estimated rates of bacterial productivity. In lagoonal areas not colonized by shrimps, primary productivity (400–1100 mg C m-2d-1) from algal mats was sufficient to support bacterial growth. It is suggested that deposit-feeding macrobenthos such as thalassinid crustaceans play a major role in the tructuring and functioning of lower trophic groups (bacteria, microalgae, protozoa, meiofauna) in coral reef sedments, particularly in laggons.  相似文献   

10.
Storm floods on the night of December 31, 1987 reduced salinity to 15 in the surface waters of Kaneohe Bay, resulting in massive mortality of coral reef organisms in shallow water. A spectacular phytoplankton bloom occurred in the following weeks. Phytoplankton growth was stimulated by high concentrations of plant nutrients derived partially from dissolved material transported into the bay by flood runoff and partially by decomposition of marine organisms killed by the flood. Within two weeks of the storm, chlorophyll a concentrations reached 40 mg m-3, one of the highest values ever reported. The extremely rapid growth rate of phytoplankton depleted dissolved plant nutrients, leading to a dramatic decline or crash of the phytoplankton population. Water quality parameters returned to values approaching the long-term average within 2 to 3 months. Corals, echinoderms, crustaceans and other creatures suffered extremely high rates of mortality in shallow water. Virtually all coral was killed to depths of 1–2m in the western and southern portions of the bay. Elimination of coral species intolerant to lowered salinity during these rare flood events leads to dominance by the coral Porites compressa. After a reef kill, this species can eventually regenerate new colonies from undifferentiated tissues within the dead perforate skeleton. Catastrophic flood disturbances in Kaneohe Bay are infrequent, probably occurring once every 20 to 50 years, but play an important role in determination of coral community structure. The last major fresh water reef kill occurred in 1965 when sewage was being discharged into Kaneohe Bay. Coral communities did not recover until after sewage abatement in 1979. Comparison between recovery rate after the two flood events suggests that coral reefs can recover quickly from natural disturbances, but not under polluted conditions.  相似文献   

11.
In this study, we present exact measures of the number, area, and basic morphometric statistics for every single reef of the Maldivian archipelago, as derived from the interpretation of remotely sensed data collected by the Landsat-7 ETM+ earth-observing satellite sensor. We classified and mapped seven morphological attributes of reefs (six marine habitats and reef-top islands) to 30-m depth at 30×30 m spatial resolution (pixel size) for the entire archipelago. The total archipelagic area (all coral reef and lagoon habitats) of the 16 atolls, five oceanic faros, and four oceanic platform reefs which comprise the Maldives is 21,372.72±1,068.64 km2 (approx. 20% of the Maldives Territorial Sea). A total of 2,041±10 distinct coral reef structures larger than 0.01 km2 occur in the Maldives, covering an area of 4,493.85 km2 (including enclosed reef lagoons and islands) to 30-m depth. Smaller areas of coral reef substratum cover another 19.29 km2, bringing the total area of Maldivian coral reefs to 4,513.14±225.65 km2. Shallow coral platforms thus occupy 21.1% of the total area of the archipelago (0.0052% of the EEZ area of the Maldives). Of these reefs, 538 are rim and oceanic reefs, covering 3,701.93 km2 (82.5% of the total reef area), and 1,503 are patch reefs within the atoll lagoons, covering 791.92 km2 (17.5% of the total reef area). Islands occupy only 5.1% of the total reef area. Mapping the Maldives coral reefs at high spatial resolution is only possible with remote sensing and spatial analysis technologies. These greatly reduce the large uncertainty around current estimates of reef area. Our accurate measure of total reef area is only 50.6% of the current best estimate, a result having significant implications for predictions of the Maldives reef productivity and response to global climate change. Here we present current best practice and compare the methods and measures with previous approaches.  相似文献   

12.
Alterations in intracellular Zn2+ concentrations are believed to play a crucial role in modulating apoptosis. The observation that Zn2+ deficiency can induce cell death both in vivo and in vitro has been attributed to the fact that exchange of Zn2+ for Ca2+ and Mg2+ within the nuclei may directly activate endogenous endonucleases therefore inducing DNA fragmentation independent of cytoplasmic factors. Here we show that the membrane-permeable zinc chelator, N,N,N-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN) induces translocation of cytochrome c from the mitochondrial intramembranous space into the cytosol in human peripheral blood T lymphocytes (PBL) with subsequent activation of caspases-3, -8, and -9. Pretreatment of T lymphocytes with caspase inhibitors Z-VAD.fmk or DEVD.fmk prevented DNA fragmentation in response to TPEN indicating that apoptosis triggered by zinc deficiency is entirely dependent on activation of caspase family members. The release of cytochrome c and activation of downstream caspases precedes changes in the mitochondrial transmembrane potential ( m). Therefore, cytoplasmic and mitochondrial events are critical to this process.  相似文献   

13.
Unusual disease lesions were observed in Montipora corals on the fringing reef of Magnetic Island (Great Barrier Reef, Australia) following a period of high water temperature in early January 2002. Tissue death in Montipora spp. appeared as a black layer that spread rapidly across the colony surface, though this appeared as the final phase of disease progression (with three previous disease phases now identified, S. Anthony, unpublished). Culture and molecular-based microbial analysis of this layer did not identify a likely microbial pathogen. Despite this, DNA sequencing of microbial 16S rDNA indicated a shift in the bacterial population associated with affected coral tissue. A clone library of the healthy coral sample predominantly contained sequences within the -Proteobacteria. A disease coral sample representing the margin of the black lesion and healthy coral tissue was dominated by sequences, which demonstrated low sequence identity to a range of -Proteobacteria, -Proteobacteria and cyanobacteria. The microbes identified in the diseased Montipora spp. samples are likely to be opportunistic rather than the causative agent of the observed lesion. Studies are in progress to further characterise the ecology of this disease and describe the potential microbial pathogen(s).  相似文献   

14.
Summary Cytoplasmic-genic male-sterility systems are used to economically produce hybrid onion seed. Previous studies have indicated that the source of cytoplasmic male sterility discovered in 1925 by Jones (S-cytoplasm) may be an alien cytoplasm. Restriction enzyme analysis of the chloroplast DNA (cpDNA) revealed five polymorphisms between S and normal (N) fertile cytoplasms. S-cytoplasm was different from the Allium species closely related to the bulb onion, and cladistic estimates of phylogenies supported introduction from an unknown species. S-cytoplasm was identical for all polymorphisms in the cpDNA to Pran, a triploid viviparous onion. Pran shares morphological characteristics with Italian Red 13–53, the single plant source of S-cytoplasm. Densiometric scans of autoradiograms revealed that 12 of 31 open-pollinated populations of onion possessed S-cytoplasm and that introgression may have occurred since the discovery of S-cytoplasm.  相似文献   

15.
Long-term observations on coral units and their coral fishes, as well as observations on the growth of colonies of marked corals in the Gulf of Aqaba (Red Sea), have revealed the relationship between coral dimension and complexity and the ecomorphology and sociobiology of the inhabiting fishes. In this study, coral fishes are identified as species that, following the planktonic interval, settle and remain in a selected coral or its immediate vicinity. Parallel with growth of the refuge, the number of fishes in such a coral–fish association (=ecological cell) increases to a certain asymptote, forming a stable symbiotic entity of fish species, specific in composition and biomass. The initial cell begins with 4–5-year-old branching corals that harbors 3–4 cryptic species of gobies (Paragobiodon and Gobiodon species). This is followed by several stages of coral growth and increase in fish species and biomass, especially of pomacentrids, anthiases, pseudochromids and blennies. The water column or functional space from which the fishes harvest plankton, their main food source, starts at around a 0.2m3 column in the young colonies, and ends with a water column of around 500m3 in the mature ecological cells of large coral knolls. At the mature stage, large cells harbor up to 100 diurnal and nocturnal species of fish, permanently using this refuge and forming an integrated collective. The territorial limits of the piscivorous groupers (Cephalopholis species) generally establish the dimensions of these ecological cells. Preliminary data on standard energy metabolism of the fishes for mature ecological cells reveal that 800kg food is required each year to maintain this biomass. The biological composition and stability of fish populations of such ecological cells will depend on the biological and physical stability of the host coral population.  相似文献   

16.
Multivariate statistical tests are performed on three coral species to determine if a relationship exists between colony shape and corallite morphology. Hemispherical to branched colony shapes are emphasized. The material consists of specimens of Montastraea annularis and M. cavernosa from modern reef habitats in Jamaica. Colonies of the more branched M. limbata from the Neogene of the Dominican Republic are analyzed for comparison. The characters studied consist largely of linear measurements of colony dimensions and corallite structures in transverse thin-sections. The results show that different complexes of corallite characters vary within each species. With the possible exception of a complex describing theca thickness in M. annularis, none of these corallite complexes is related to variation in colony shape within species. Colony shape variation within species is related to upward colony growth rate. These results indicate that corallite morphology and colony shape can be represented by two different vectors of variation within species. Comparisons of intraspecific with interspecific patterns suggest that a strong genetic component explains colony shape variation in corals.  相似文献   

17.
Patterns of hard coral and sea urchin assemblage structure (species richness, diversity, and abundance) were studied in Kenyan coral reef lagoons which experienced different types of human resource use. Two protected reefs (Malindi and Watamu Marine National Parks) were protected from fishing and coral collection, but exposed to heavy tourist use. One reef (Mombasa MNP) received protection from fishermen for one year and was exploited for fish and corals prior to protection and was defined as a transitional reef. Three reefs (Vipingo, Kanamai, and Diani) were unprotected and experienced heavy fishing and some coral collection. Protected and unprotected reefs were distinct in terms of their assemblage structure with the transitional reef grouping with unprotected reefs based on relative and absolute abundance of coral genera. Protected reefs had slightly higher (p<0.01) coral cover (23.6 ± 8.3 % ± S.D.) than unprotected reefs (16.7 ± 8.5), but the transitional reef had the highest coral cover (30.8 ± 6.4) which increased by 250% since measured in 1987: largely attributable to a large increase inPorites nigrescens cover. Protected reefs had higher coral species richness and diversity and a greater relative abundance ofAcropora, Montipora andGalaxea than unprotected reefs. The transitional reef had high species richness, but lower diversity due to the high dominance ofPorites. Sea urchins showed the opposite pattern with highest diversity in most unprotected reefs. Coral cover, species richness, and diversity were negatively associated with sea urchin abundance, but the relative abundance ofPorites increased with sea urchin abundance to the point wherePorites composed >90% of the coral cover at sites with the highest sea urchin abundance. Effects of coral overcollection was only likely for the genusAcropora (staghorn corals). A combination of direct and indirect effects of human resource use may reduce diversity, species richness, and abundance of corals while increasing the absolute abundance of sea urchins and the relative cover ofPorites.  相似文献   

18.
This paper explores the social and cultural organization of Iranian emotional discourse and its transformation in post-revolutionary Iran. First, the Moharram dramas we participated in during field research are described, indicating how these performances organized a prototypical view of the social order, the self, and the passions. Using Kapferer's distinction between transcendental and transformative rituals, we argue that these dramas were traditionally organized as transcendental rites. Second, data on grieving rituals and depressive illness among Iranians is introduced, focusing on the transformative qualities of mourning rites and suggesting an interpretation of depression as a failure of the work of culture. Third, the appropriation of these symbolic forms of society, self, and the emotions by the current Iranian Islamic state and the role of the state in defming the meaning and legitimacy of emotions and their expression is analyzed.  相似文献   

19.
In vitro raised shoots of Mentha arvensis L. were screened for menthol tolerance level by growing them in media containing 0–100 g ml–1 menthol. A total of 2850 regenerated shoots were step wise screened for menthol tolerance at the concentrations of 50 g ml–1 followed by 60 and 70 g ml–1. In this screening, only 30 individual regenerated shoots were able to survive. The clones from the primary screen were inoculated into rooting medium and, after rooting, transferred to pots in the greenhouse. Ultimately, these 30 menthol tolerant clones were multiplied and grown in the field in replicated plots of 2.5×2.5 m sizes. Twigs of 30 clones from the replicated trials were rechecked for tolerant phenotypes at a concentration of 70 g ml–1 menthol wherein, these survived even after 7 days (secondary screening). These clones were checked for oil and menthol content and were found to be better than the control plants. Out of these 30 plants, five tolerated 80 g ml–1 menthol (tertiary level screening) and were found to contain the highest amount of menthol per g leaf biomass. Molecular analysis through RAPD showed distinct variation in the profiles of these five plants, in comparison to the control. Using this method the relationship between the primer OPT 04, menthol tolerance and high menthol content character of the genotype was established. Further, a cultivar `Saksham' was released from the selections by CIMAP for superior performance.  相似文献   

20.
Fifty-seven species of hermatypic corals have been maintained and grown in high-nutrient seawater at the Waikiki Aquarium, Honolulu, Hawaii. In this study we document the chemical conditions of aquarium water in terms of dissolved nutrients and carbon. Aquarium water is characterized by concentrations of inorganic nutrients that are high relative to most natural reef ecosystems: SiO3 200 M; PO4 0.6 M; NO3 5 M; NH4 2 M. In contrast, concentrations of organic nutrients are lower than most tropical surface ocean waters: DOP 0.1 M and DON 4 M. The incoming well-water servicing the facility has low pH, crating over-saturation of carbon dioxide. The coral communities in aquaria took up inorganic nutrients and released organic nutrients. Rates of nutrient uptake into aquaria coral communities were similar to nutrient uptake by natural reef communities. Coral growth rates were near the upper rates reported from the field, demonstrating corals can and do flourish in relatively high-nutrient water. The growth of corals does not appear to be inhibited at concentrations of nitrogen up to 5 M. Statements implying that corals can only grow in low nutrient oligotrophic seawater are therefore oversimplifications of processes that govern growth of these organisms. Some basic guidelines are given for maintenance of coral communities in aquaria.  相似文献   

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