Assessing Metal Content in Halophila stipulacea Seagrass as an Indicator of Metal Pollution in the Northern Gulf of Aqaba, Red Sea

Tariq Al-Najjar,Mohammad Wahsha,Mwaffaq Al-Khushman,Maroof Khalaf,Kyle Hardage,Wissam Hayek,Khalid Abu Khadra,Adina Paytan 한국해양과학기술원 2021 Ocean science journal Vol.56 No.4

To assess the utility of the seagrass (Halophila stipulacea) for biomonitoring of metal pollution, seagrass samples were collected from four sites along the Jordanian coast of the Gulf of Aqaba between April and July 2017. Concentrations of trace metals (Cr, Mn, Fe, Ni, Zn, and Pb) in leaves, rhizomes, and roots were compared to published data on sediment trace metal and organic carbon content at the same sites to assess the degree of their fidelity in recording local trace metal pollution. The results of this study indicated that the roots of the seagrass H. stipulacea accumulated higher metal concentrations of Cd, Pb, Cr, Ni, Zn, Mn, and Fe than rhizomes and leaves. Concentrations in H. stipulacea varied significantly between sites for Mn, Fe, Zn, Cd, and Pb but not for Cr and Ni. Higher levels of seagrass trace metals in the Hotels Area and Old Phosphate Port sampling sites compared to other sampled sites are likely related to the sites' proximity to tourist and boating activity and city infrastructure which may contribute to metals accumulating in the tissues of this seagrass. In contrast to other studies, when all the data are considered, no clear trend between sediment metal concentration and seagrass metals is observed, suggesting physiological control on metal uptake by H. stipulacea and thus limiting the utility of H. stipulacea for biomonitoring of pollution.

Neighboring Cage Fish Farming Affecting Water and Seabed Quality of the Jordanian Northern Gulf of Aqaba, Red Sea

Al-Zibdah Mohammad,Oqaily Firas,Al-Najjar Tariq,Manasrah Riyad1 한국해양과학기술원 2008 Ocean science journal Vol.43 No.1

Environmental qualities of coastal water and bottom sediment were assessed at Jordan’s northernmost tip of Gulf of Aqaba to evaluate possible impacts of the bordering fish pen cages in Eilat. Results showed significant differences between surface and bottom water in the chemical and physical variables in the different months of the year (2004-2005). Chlorophyll a was also significantly higher in bottom water when compared to that of the offshore water. Nitrate and ammonia were significantly higher in bottom water than the surface water at each individual station. The upper 2 cm of sediment sample recorded higher values of total phosphorus and organic matter. Seasonality affected the content of total phosphorus, organic matter, redox potential and color especially at the sediment layer below 3 cm of the sediment core. The present investigation showed slight modification of water and sediment qualities but no clear sign of eutrophication was observed. However, to maintain sustainability of healthy environmental conditions at the northern tip of Gulf of Aqaba potentials of any possible environmental risks arising from the fish farms or any other coastal investment should be carefully considered.

Neighboring Cage Fish Farming Affecting Water and Seabed Quality of the Jordanian Northern Gulf of Aqaba, Red Sea

Mohammad, Al-Zibdah,Firas, Oqaily,Tariq, Al-Najjar,Riyad, Manasrah The Korean Society of Oceanography 2008 Ocean science journal Vol.43 No.1

Environmental qualities of coastal water and bottom sediment were assessed at Jordan's northernmost tip of Gulf of Aqaba to evaluate possible impacts of the bordering fish pen cages in Eilat. Results showed significant differences between surface and bottom water in the chemical and physical variables in the different months of the year (2004-2005). Chlorophyll a was also significantly higher in bottom water when compared to that of the offshore water. Nitrate and ammonia were significantly higher in bottom water than the surface water at each individual station. The upper 2 cm of sediment sample recorded higher values of total phosphorus and organic matter. Seasonality affected the content of total phosphorus, organic matter, redox potential and color especially at the sediment layer below 3 cm of the sediment core. The present investigation showed slight modification of water and sediment qualities but no clear sign of eutrophication was observed. However, to maintain sustainability of healthy environmental conditions at the northern tip of Gulf of Aqaba potentials of any possible environmental risks arising from the fish farms or any other coastal investment should be carefully considered.

Seasonal Changes of Water Properties and Current in the Northernmost Gulf of Aqaba, Red Sea

Manasrah, Riyad,Zibdah, Mohammad,Al-Ougaily, Firas,Yusuf, Najim,Al-Najjar, Tariq The Korean Society of Oceanography 2007 Ocean science journal Vol.42 No.2

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 wind-induced 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 $12cms^{-1}$ respectively.

Seasonal Changes of Water Properties and Current in the Nothernmost Gulf of Aqaba, Red Sea

Riyad Manasrah,Mohammad Zibdah,Firas Al-Ougaily,Najim Yusuf,Tariq Al-Najjar 한국해양과학기술원 2007 Ocean science journal Vol.42 No.2

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 wind-induced 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.