The global decline of coral reefs heightens the need to understand how corals respond to changing environmental conditions. Corals are metaorganisms, so-called holobionts, and restructuring of the associated bacterial community has been suggested as a means of holobiont adaptation. However, the potential for restructuring of bacterial communities across coral species in different environments has not been systematically investigated. Here we show that bacterial community structure responds in a coral host-specific manner upon cross-transplantation between reef sites with differing levels of anthropogenic impact. The coral Acropora hemprichii harbors a highly flexible microbiome that differs between each level of anthropogenic impact to which the corals had been transplanted. In contrast, the microbiome of the coral Pocillopora verrucosa remains remarkably stable. Interestingly, upon cross-transplantation to unaffected sites, we find that microbiomes become indistinguishable from back-transplanted controls, suggesting the ability of microbiomes to recover. It remains unclear whether differences to associate with bacteria flexibly reflects different holobiont adaptation mechanisms to respond to environmental change.

No abstract

No abstract

A four-step sequential extraction technique was used to determine the chemical association of heavy metals (Cd, Cu, Pb, Zn) with major sedimentary phases (exchangeable and carbonates, manganese and iron oxides, sulphides and organic matter and residual minerals) in samples from Al Shabab Lagoon, Jeddah, S.A. The total metal content was also determined. The results of the present study indicate that the bottom sediments of the lagoon contain high concentrations of heavy metals such as Cd, Cu, Pb and Zn. The partitioning characteristics of the lagoon sediments also show that the percentages of metals associated with the non-residual fractions are notably greater than the residual fraction, for all studied metals, indicating the polluted nature of the sediments. The Risk Assessment Code reveals that about 30-45% of Cd at most of the sites exist in exchangeable and carbonate bound fraction and therefore comes under the high risk category and can easily enter the food chain. A sizable portion of Pb and Zn (4.6-15.4 and 2.5-14.5% of Pb and Zn, respectively) is found in exchangeable and carbonate bound fraction thus posing low to medium risk for the aquatic environment. Fractionation pattern of Cu shows no to low risk to aquatic environment.

No abstract

No abstract

No abstract

Abststract. Environmental pollution that renders shore waters unsatisfactory for public use has become a global health problem. This study was carried out to examine certain pollution-indicating water quality parameters in sampling stations located at Al-Nawrus lagoon (North of Jeddah) during June 2005-January 2006. These parameters included: aerobic heterotrophic bacteria, total coliform (TC), fecal coliform (FC), dissolved oxygen (DO), and nutrients (NO 2-N, NO 3-N, NH 4-N and PO 4-P). DO and nutrient concentrations varied greatly in the water at different sampling stations compared with their respected values in the open sea. A comparison of the mean values of nutrients in Al-Nawrus lagoon with those of other locations in the Red Sea suggests that the mean levels of NO 3 were similar to those of polluted areas, whereas mean concentrations of NO 2 , NH 4 and PO 4 were generally similar to those of unpolluted or slightly polluted areas. Counts of aerobic heterotrophic bacteria, TC and FC did not show any seasonal pattern. Highest counts of aerobic heterotrophic bacteria were obtained at stations towards the north and the lowest were recorded at stations toward the south. Similarly, TC and FC counts were higher at the north sampling stations than the south ones, and with little variations between their numbers. FC was not recovered at stations to the south. The study shows that aerobic heterotrophic bacteria, except at certain sampling stations similar to the levels reported for normal unpolluted sea water.