Coral Reef Samples Research Articles

Utilization of INAA Technique for Studying the Negative Impact of Human Activities on Coral Reefs in the Quseir harbour area

Coral reef samples collected from the Egyptian Red Sea coast’s Quseir harbour were analysed using the INAA technique for qualitative and quantitative analysis. The concentration of heavy metals, rare earth elements, and elemental contents were measured in coral reefs. The samples were assembled with their standards and irradiated in Egypt’s Second Research Reactor at the same time (ETRR-2). The gamma-ray spectra of an HPGe detector with a 100 percent relative efficiency were studied. The elements determined are: Al, Ti, Na, K, Mg, V, Cl, Ca, Mn, Cr, As, Co, Zn, Fe, Br, Tb, Zr, Hf, Sb, Ba, Sc, Nd, La, Sm, Ce, Eu, Yb, Ta, U, and Th. The present work is worried about the use of INAA to attain an accurate knowledge about the elemental content in coral reef samples in the Quseir harbour area and revealing potential environmental indicators for heavy metals contamination as well as pollution hot spot throughout this area to assess the public health for workers, tourists, and the surrounding population.

Ecological Impacts of Coral Reefs, Egyptian Red Sea Coast: Elemental Characterization and Spatial Distribution with INAA

ABSTRACT Instrumental neutron activation analysis (INAA) is a well-accepted technique that has the ability to simultaneously determining 30–40 elements. INAA is also capable of determining major, minor, and trace elements as well as rare earth elements. It was utilised to determine the concentration of heavy elements and elemental contents of coral reef samples collected from three locations on the Red Sea coast of Egypt. The coral reef samples were prepared with their standard materials and together irradiated in Egypt Second Research Reactor (ETRR-2). For short and long irradiations, samples were separately irradiated at a convenient thermal neutron flux 4 × 1011cm−2s−1 for 2 min in a pneumatic rabbit system and samples were irradiated at a thermal neutron flux 1.5x1014cm−2s−1 for 32 mins, respectively. All samples were counted two times in a HPGe detector with a relative efficiency of 100% for short and long irradiations. The following elements have been determined Al, Ti, Na, K, Mg, V, Cl, Ca, Mn, Cr, As, Co, Zn, Ni, Fe, Br, Tb, Zr, Hf, Sb, Ba, Sc, Nd, La, Sm, Ce, Eu, Yb, Ta, U, and Th. In the Quseir harbour, the maximum concentration of Al, Fe, Mn Zn, U, and Th were 3487 ± 74, 2007 ± 22, 33 ± 0.5, 119 ± 0.5, 4 ± 0.3, and 0.52 ± 0.04 mg/kg, respectively. These concentrations were higher for these elements compared to other areas. The present work is concerned to achieve precise information about the elemental content in coral reef samples along the Red Sea coast in specific locations and the effect of detected concentrations on the surrounding environment.

NITROGEN CONCENTRATION IN CORAL REEF: THE CONTRIBUTION OF CORAL FORMS AND NITROGEN FIXING BACTERIA IN KARIMUNJAWA ISLANDS

Coral is an ecosystem in the coastal area which plays an important role in controlling nutrient cycle in the sea. This research aimed to study the the nitrogen concentration in coral and to analyze the influence of nitrogen fixing bacteria on the concentration of nitrogen in coral. The research was carried out by field observation, by taking coral reef samples and analyzed in the laboratory for its nitrogen concentration and number of nitrogen fixing bacteria. Data analysis was carried out by ANOVA and regression. The analysis resulted that there was a significant difference of nitrogen concentration in massive and branching corals. However, there is no significant correlation between the sampling location and types of coral on the density of nitrogen fixing bacteria, both Nitrosomonas sp. and Nitrobacter sp. Regression analysis showed that the concentration of nitrogen in coral tissue was not significantly related to the density of nitrogen fixing bacteria. The result of this research implies that the concentration of nitrogen in the coral tissue may be affected by many other factors.

Predominance of Harveyi clade luminous bacteria in coastal waters of South Andaman, India

The diversity, distribution, and mechanisms of bacterial speciation of Vibrio species belonging to Harveyi clade are an important global research interests due to their pathogenic activity in coastal environments. Luminous bacteria are also known to act as environmental indicators in coastal waters. This study demonstrates that luminous bacteria belonging to harveyi clade are predominant in seawater, sediment, surfaces of marine animals and plants, and light organs of leiognathid fishes. Molecular phylogenies for eighteen morphologically distinct and potentially luminous strains chosen out of 57 isolated luminous bacteria. Sequence analysis of luxA gene as a molecular marker identified luminous bacteria belonging to Harveyi clade, Photobacterium clade, and Anguillarum clade distinctly. Rich biodiversity and distribution of luminous bacterial species (30% to 40%) was found in association with coral reef samples of south Andaman. This study confirms and reveals the evidence on predominant association of Harveyi clade luminous vibrio's in coastal waters of south Andaman.

ANALISIS KADAR KALSIUM OKSIDA (CaO) PADA BATU KARANG DI DAERAH PESISIR BAYANG DAMPELAS DONGGALA

Coral reefs are classified as coral or coral limestone. These corals contain of a high level of calcium purity with more than 90%. These clacium are in the from calcite (CaCO3). Calcite can be used in the industrial sector wich can be processed into a catalyst and use as a mixture 0f portland cement.its economic value increases by converting CaCO3 to CaO trough the calcination process at high temperatures. The coral sampels were taken from the coastal area of Bayang, Dampelas Donggala wich consisted of 2 samples. i.e coastal and montain coral reefs. The CaO levevls contained in coral reefs wer determined by qualitative and quantitative analysis method using XRF (X-Ray Fluorescence). XRF result showed that were CaO compounds in each coral reef sample. The CaO level in the coastal reef was 92,08% before calcination and 92,11% after calcination. Whereas the CaO level in te mountain coastal reef was 94,51% before calcination and 96,77% after calcination.

Mineralogical determination of reef and periplatform carbonates: Calibration and implications for paleoceanography and radiochronology

Detection and precise quantification of the different carbonate minerals is crucial in selecting coral reef samples prior to geochemical and radiochronological measurements, thus helping to interpret changes in the mineralogical composition of geological formations made of reef material and associated sediments such as periplatform oozes. While powder X-ray diffraction (XRD) is a widely used method for mineralogical analysis, precise and accurate quantification of mineral abundance requires a thorough calibration of the instrument and method by means of gravimetric standards. In this study, we optimize a calibration method for the quantitative determination of four widespread Ca and Mg carbonates: calcite, aragonite, magnesian calcite (Mg-calcite) and dolomite. To detect and quantify very low calcite contents, which provide a crucial screening criterion for coral radiochronology, we perform a detailed survey of analytical precision and limits using two different XRD facilities. Detection and quantification limits (≈ 0.18% and ≈ 0.9% calcite in a calcite–aragonite mixture, respectively) are shown to be similar between the two instruments. The reproducibility of measurements clearly demonstrates that it is preferable to use peak area rather than peak height alone to obtain a precise quantification of the abundances of various carbonate minerals.

ESR dosimetric properties of modern coral reef

Modern coral reef samples from Egypt were irradiated with 60Coγ-rays to study radicals for dosimetric materials with electron spin resonance (ESR). The ESR spectrum for the radical species in unirradiated coral is characterized by four signals with spectroscopic splitting factors of g=2.0056, 2.0030, 2.0006 and 1.997. The signal at g=2.0006±0.0005 is ascribed to free rotation CO 2 − radicals and used as a dosimetric one. The response to γ-ray doses ranging from 5 to 10 3 Gy and the thermal stability has been studied. The number of free radicals per 100 eV (G-value) was found to be 0.45 ± 0.1 and 0.9 ± 0.18 for coral and alanine, respectively. The lifetime of radicals and the activation energy were estimated from Arrhenius plots to be approximately 8 × 10 5 ± 1.6 × 10 5 years, and 1.12 eV, respectively.

DNA hybridization to compare species compositions of natural bacterioplankton assemblages

Little is known about the species composition and variability of natural bacterial communities, mostly because conventional identification requires pure cultures, but less than 1% of active natural bacteria are cultivable. This problem was circumvented by comparing species compositions via hybridization of total DNA of natural bacterioplankton communities for the estimation of the fraction of DNA in common between two samples (similarity). DNA probes that were labeled with 35S by nick translation were hybridized to filter-bound DNA in a reciprocal fashion; similarities (in percent) were calculated by normalizing the values to self-hybridizations. In tests with DNA mixtures of pure cultures, the experimentally observed similarities agreed with expectations. However, reciprocal similarities (probe and target reversed) were often asymmetric, unlike those of DNA from single strains. This was due to the relative complexity and G + C content of DNA, which provided a means to interpret the asymmetry that was occasionally observed in natural samples. Natural bacteria were collected by filtration from Long Island Sound (LIS), N.Y., the Caribbean and Sargasso seas, and a coral reef lagoon near Bermuda. The samples showed similarities of less than 10 to 95%. The LIS and Sargasso and Caribbean sea samples were 20 to 50% similar to each other. The coral reef sample was less than 10% similar to the others, indicating its unique composition. Seasonality was also observed; an LIS sample obtained in the autumn was 40% similar to two LIS samples obtained in the summer; these latter two samples were 95% similar. We concluded that total DNA hybridization is a rapid, simple, and unbiased method for investigating the variation of bacterioplankton species composition over time and space, avoiding the need of culturing.