Tariq Al-Najjar

Seasonal dynamics of phytoplankton in the Gulf of Aqaba, Red Sea

Seawater samples were collected biweekly from the northern Gulf of Aqaba, Red Sea, for Phytoplankton analysis during the period May 1998 to October 1999. Microscopic counts and HPLC methods were employed. Procaryotic and eucaryotic ultraplankton dominated throughout most of the year, with larger nano- and microplankton making up only 5% of the photosynthetic biomass. Moderate seasonal variations in the 0–125 m integrated Chl a contrasted with a pronounced seasonal succession of the major taxonomic groups, reflecting the changes in the density stratification of the water column: Prochlorococcus dominated during the stratified summer period and were almost absent in winter. Chlorophyceae and Cryptophyceae were dominant during winter mixing but scarce or absent during summer. Diatoms and Synechococcus showed sharp and moderate biomass peaks in late winter and spring respectively, but remained at only low Chl a levels for the rest of the year. Chrysophyceae, Prymnesiophyceae and the scarce Dinophyceae showed no clear seasonal distribution pattern. The implications of alternating procaryotic and eucaryote dominated algal communities for the Red Sea pelagic food web are discussed.

Marine litter in coral reef areas along the Jordan Gulf of Aqaba, Red Sea.

Composition and abundance of submerged marine litter at six selected sites within a coral reef area along the Jordanian coast of the Gulf of Aqaba have been estimated. The litter was collected in clean up voluntary campaigns that took place in the period between 25 August 2003 and 29 February 2004. A total of 10,506 items weighing 1159 kg were collected during the survey. Mean litter density in the individual sampling sites varied between 1 and 6 items/m(2) with an overall mean density of 2.8 items/m(2). The mean weight of the collected items per sampling site varied between 0.06 and 1.06 kg/m(2) with an overall mean of 0.31 kg/m(2). Plastic accounted for 42% of the collected items, fishing gear was the second most abundant (31%) while metal was the third most abundant item (17%). By comparison, cardboard constituted 1%, and rubber and other items accounted for less than 1% of the total items collected during the campaigns. Approximately 61% of the plastics consisted of bags followed by bottles (24%), plastic containers and sheets accounted for 13 and 2%, respectively. Statistical analysis indicates no significant differences between the sites in terms of litter count and weight. Potential sources are pointed out and recommendations and actions to address the problem are suggested.

Plastic pellets on the beaches of the northern Gulf of Aqaba, Red Sea

The occurrence of plastic pellets on the Jordanian beaches along the northeastern side of the Gulf of Aqaba (Red Sea) is being reported for the first time. Five beaches of about 4,650 m in length and 134,000 m 2 in area were surveyed for the presence of these spherules during two successive years. Pellets with a variety of colors, shapes and sizes were found. The presence of these pellets is most likely due to accidental spillages: cargo loss during sea transport and sweeping of raw plastic materials, such as those imported as feedstock for local plastic factories in Jordan, into shore by wave action. When compared with other beaches of other parts of the world, the Jordanian beaches on the Gulf of Aqaba are considered heavily polluted with these pellets. This report discusses type, degree of degradation, sources and possible effects on the marine environment and suggests actions to reduce the input of plastic pellets to the marine environment at the source.

ASSESSMENT OF GAMMA-EMITTING RADIONUCLIDES IN SEDIMENT CORES FROM THE GULF OF AQABA, RED SEA

The Gulf of Aqaba is the only seaport in Jordan which currently has intense activities such as industrial development, phosphate ore exportation, oil importation, shipping, commercial and sport fishing. Most of these activities, especially the phosphate ore exportation, could cause serious radiological effects to the marine environment. Thus, it is essential to investigate the level of the radioactivity concentrations to establish a baseline database, which is not available yet in the Gulf of Aqaba. Radioactivity concentrations of gamma-emitting radionuclides in core and beach sediments of the Gulf of Aqaba were investigated. Core sediments were collected from five representative locations for three different water column depths (5, 15 and 35 m). The results showed that the activity concentrations of 238U, 235U and 226Ra for both seafloor and beach sediments from the phosphate loading berth (PLB) location to be higher than those from other investigated locations and more than twice as high as the worldwide average; the 238U activity concentration was found to vary from 57 to 677 Bq kg(-1). The results also showed that there is little variation of radioactivity concentrations within the core length of 15 cm. The calculated mean values of the radium equivalent activity Ra(eq), the external hazard index, H(ex), the absorbed dose rate and the annual effective dose for the beach sediment in PLB location were 626 Bq kg(-1), 1.69, 263 nGy h(-1) and 614 µSv y(-1), respectively. These values are much higher than the recommended limits that impose potential health risks to the workers in this location. As for other studied locations, the corresponding values were far below the maximum recommended limit and lies within the worldwide range.

Seasonal changes of water properties and current in the northernmost gulf of aqaba, red sea

Seasonal changes of tide signal(s), temperature, salinity and current were studied during the years 2004-2005 in the northernmost Gulf of Aqaba, which is under developmental activities, to obtain scientific bases for best management and sustainability. Spectrum analysis revealed permanent signals of tide measurements during all seasons, which represented semidiurnal and diurnal barotropic tides. The other signal periods of 8.13, 6.10-6.32, 4.16 and 1.02-1.05 h were not detected in all seasons, which were related to shallow water compound and overtides of principle solar and lunar constituent and to seiches generated in the Red Sea and the Gulf of Aqaba. Spatial and temporal distribution of temperature, salinity and density showed significant differences between months in the coastal and offshore region and no significant differences among the coastal sites, between the surface and bottom waters and between coastal and offshore waters. Therefore, the temporal and spatial variation of water properties in the northernmost Gulf of Aqaba behave similarly compared to other parts. The coastal current below 12 m depth was weak (3-6 cms-1) and fluctuated from east-northeastward to west-southwestward (parallel to the shoreline), which may be related to the effect of bottom topography and/or current density due to differential cooling between eastern and western parts in the study area, and windinduced upwelling and downwelling in the eastern and western side, respectively. The prevailing northerly winds and stratification conditions during summer were the main causes of the southward current at 6 and 12 m depths with average speed of 28 and 12 cms-1, respectively.

Potential environmental impact of dissolution of raw phosphate in sea water of the Gulf of Aqaba

Dissolution of raw phosphate (apatite) in sea water of the Gulf of Aqaba was investigated through lab incubation experiments. Three types from three different sources (Al-Hasa, Al-Abyad and Esh-Shydiya) have been used for these experiments. Impact of quantity, grain size, and source (type) of raw phosphate on dissolution rate were studied. Statistical analysis shows significant differences between the results obtained from comparing each two weights; as weight of apatite increased, dissolved inorganic phosphate-phosphorus (DIP) and fluoride in sea water solution increased. The differences between the dissolution rates of raw phosphate from the three sites were not significant while the differences between the different grain size fractions were significant. Dissolution rates were inversely related to particle size. Using a worst-case scenario, a conservative estimate of the maximum increase in DIP in seawater of the Gulf of Aqaba due to the apatite particles lost to the sea during ship loading resulted in DIP concentrations of 0.03 μM per year. As the residence time of the water in the Gulf of Aqaba is about one year, the DIP concentration will not increase by more than 0.03 μM under the estimated annual quantity of exported phosphate. Fluoride will not increase by more than 0.03 mg/l under the same conditions.

Biochemical and histopathological effects of the stonefish (Synanceia verrucosa) venom in rats

&NA; The Reef Stonefish (Synanceia verrucosa) is one of the most dangerous venomous fish known, and has caused occasional human fatalities. The present study was designed to examine some of the pathological effects of the venom from this fish in Sprague Dawley rats. Crude venom was extracted from venom glands of the dorsal spines of stonefish specimens collected from coral reefs in the Gulf of Aqaba (in the northeastern branch of the Red Sea). The rats were given intramuscular injections of the venom and acute toxicity and effect on selected serum marker enzymes as well as normal architecture of vital organs were evaluated. The rat 24 h LD50 was 38 &mgr;g/kg body weight. The serum biochemical markers; alanine transaminase (ALT), lactate dehydrogenase (LDH) and creatine kinase (CK) increased after 6 h of administration of a sub lethal dose of the venom and remained significantly raised at 24 h. Amylase levels also significantly increased after venom injection. The venom caused histological damage manifested as an interstitial hemorrhage, inflammatory cell infiltration, and necrosis. The demonstrated rises in the levels of different critical biochemical parameters in the serum may have led to the observed abnormal morphological changes in these organs. These results may account for some of the clinical manifestations observed in victims of stonefish envenomation. Thus, the presented data provide further in vivo evidence of the stonefish toxic effects that may threaten human life and call for the need for special measures to be considered. Graphical abstract Figure. No caption available. HighlightsStonefish worlds most venomous fish ever encountered by man.Venom highly toxic; rat LD50 38 &mgr;g/kg.Serum enzymes significantly increased.Sever histological damages may occur in human victims.Potential risk and precautious measures should be taken.