This research was aimed at studying the general environmental status of the marina at Royal Yacht Club (RYC), which is located in the Jordanian Gulf of Aqaba. The physical properties (temperature, salinity and density) were measured at surface and bottom water at 19 sites (T1 - T19). Total hydrocarbon was measured at surface at 12 sites (HC1-HC12). The water exchange and residence time were calculated using data of current speed and direction at 16 sites (C1 - C16). The mean values of temperature, salinity and density at surface and bottom waters in the RYC’s marina were 27.13°C ± 0.03°C, 40.51 ± 0.02 psu and 26.83 ± 0.02 kg·m-3, respectively. The results of physical parameters revealed no significant differences among sites, which are all comparable with open waters. The measurements range of total hydrocarbon in the marina was 1.404 mg/l (at site HC11) to 98.56 mg/l (at HC9). In general, all the high values of total hydrocarbon were found at the corners of the marina and at areas with relatively intense boats’ movements. There was no correlation between distribution of total hydrocarbon and temperature (R2 = 0.048; p = 0.49) in the marina. Therefore, the major factors that influence the distribution of total hydrocarbon within the marina are the current system and boats’ movements as well as the location reference to the gate. The residence time of waters inside the marina was 1.32 days. This flushing time is acceptable to secure good environmental conditions inside the marine to avoid stagnant seawater. The mean value of current speed at the RYC’s marina gate with open water was 5.33 ± 2.63 cm/s, which is relatively comparable with current speed in vicinity of study area. In conclusions, the environmental condition of the RYC’s marina is acceptable in term of the residence time and exchange system with open water. Slightly high values of total hydrocarbon were detected, which can be solved by regular cleaning.
The Gulf of Aqaba is the north-eastern extension of the Red Sea. The water of the Gulf of Aqaba is the warmest among the world’s seas due to the climate of the region. The Gulf of Aqaba is located in the sub-tropical arid zone between 28˚-29˚30N and 34˚30-35˚E. It is a semi-enclosed basin that extends over a length of 180 km with a width between 5 and 25 km with an average of 16 km [1-3] (
The deepest point in the Gulf reaches 1825 m with an average depth of 800 m. The bathymetry of the Gulf is arranged in three deep elongated basins separated from each other by relatively low sills. The Gulf is connected to the Red Sea by the Strait of Tiran, which has a sill depth of about 265 m [1-3].
The Gulf exhibits a seasonal cycle of stratification in spring, maintenance of a shallow thermocline in summer, and subsequent deepening of the thermocline to produce deep mixed layers in winter. Much of the seasonal stratification variability is determined by exchanges with the rest of the Red Sea. Nonetheless, inter-annual variability in wintertime temperatures appears to set the depth of maximum mixing. Because of being generally warm (T > 21˚C), and subject to dry winds much of the year, the Gulf is a site of high evaporation rates, estimated at 0.5-1.0 cm/day [1,2,4,5].
Since the Gulf is a semi-enclosed concentration basin, the combined effects of exchange flow through the strait and evaporation produce a characteristic salinity profile with a noticeable subsurface salinity minimum in summer. The high salinity levels are very close to the physiological limits of many species, which highlights the potential sensitivity of its biota to any localized anthropogenic increases [1,4].
Surface water temperature may approach 28˚C during summer months and fall to just above 20˚C in winter. Temperatures within the water mass reflect a degree of stratification versus vertical and lateral mixing by water currents. Vertically, temperature falls with depth in summer although there appears to be an inversion at certain depths in winter months because the deep water mass has a temperature reportedly above 20˚C [1,4,6].
The annual meteorological measurements demonstrate that the wind speed fluctuates within a range of 0-12 m∙s−1. Occasionally, wind speed reaches more than 15 m∙s−1 but just for few hours. Moreover, a harmonic change of wind speed appears during summer causing a diurnal cycle that is represented by strong winds during daytime and relatively weaker winds during night-time. Meanwhile, northerly winds (NNW-NNE) dominate in the Gulf and represent about 85%of total measurements [
A typical daily cycle of air temperature variations occurs during the whole year. Mean air temperature values range between 32.2˚C ± 3.16˚C in summer and 17.6˚C ± 3.46˚C in winter. In general, winds and air temperature have obvious effect on humidity; therefore, relative humidity shows periodic variation following the daily cycle of air temperature and wind speed. Minimum humidity recorded in summer is 13% compared to a maximum of 83% in winter [
Hydrocarbon is an organic compound consisting entirely of hydrogen and carbon and thus is group 14 hydride [
Oil pollution cause difficult changes of structure (causes complex changes in the structure) and function of natural ecosystems, as well as violation of metabolic processes, production and destruction of organic matter, and consequently leads to a decrease in species diversity. Studies show that planktonic animals are quite sensitive to oil pollution of seawater, which accelerates their death in the concentration of 0.01 mg∙dm−3 [
The coastal current pattern in the northern Gulf of Aqaba below 12 m depth is in general weak (3-6 cm∙s−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. [
Marina is a dock or basin with moorings and supplies for yachts and small boats. A marina differs from a port in that a marina does not handle large passenger ships or cargo from freighters. Marinas may be located along the banks of rivers connecting to lakes or seas and may be inland. They are also located on coastal harbors (natural or man-made) or coastal lagoons, either as standalone facilities or within a port complex [
The marina at Royal Yacht Club (RYC) is the oldest marina at the Jordanian Gulf of Aqaba and it includes different anthropogenic activities that may influence the quality of seawater inside and outside the marina. In this research, this marina was selected in order to study the environmental status through investigating physical properties (temperature, salinity and density), total hydrocarbon as well as water exchange system and residence time in order to assess the environmental condition of the marina and any possible impacts in open sea.
The RYC’s marina is located in northern part of Jordanian coast of the Gulf of Aqaba (
Physical properties (temperature, salinity and density) of seawater were measured using Conductivity, Temperature and Depth meter (CTD 19 plus V2) at all sites (T1-T19). The initial accuracy and resolution for the CTD sensors are ±0.0005, 0.00007 for conductivity; ±0.005, 0.0001 for temperature; ±0.1%, 0.002% for pressure, respectively.
The setup of the CTD device was prepared in the lab and then the CTD was casted in situ for measuring the seawater temperature, salinity, density at all sites (
Twelve samples were collected inside the RYC’s marina (
Water current measurements were recorded using a moored Acoustic Doppler Current Profiler (ADCP) Workhorse 300 kHz (RD Instrument) sites (
Data analysis was performed using SPSS (SPSS v.20) for statistical tests and comparisons. The Surfer software was used for drawing contours figures of all variables. Besides, Excel software was used for sorting and filtering data and drawings.
The minimum flushing time (Tflushing) of seawater inside the RYC’s marina was calculated based on the equation (
T flushing = V o l V i (1)
where:
Vol is the total water volume (m3) of seawater of RYC’s marina.
Vi is the inflow water (m3/s) through the gate at the marina, where Vi can be calculated using the following relations:
V i = A × v ¯ (2)
where
A is area of the vertical section at the gate = w ´ h,
w is the width of the vertical cross section at the gate,
h is the mean depth of the vertical section at the gate, and
v ¯ is the average of current speed that perpendicular through the cross section of the gate.
Temperature measurements in the RYC’s marina revealed weak variation among sites (
The results of temperature values in the marina are comparable with other studies in the Gulf of Aqaba. The temperature in the upper 300 m in the northern Gulf was high in summer (~26˚C) and low in winter (~21˚C) at the surface [
Salinity measurements in RYC’s marina revealed a weak variation among sites (
In general, salinity values in the marina in this study are comparable with values in the Gulf of Aqaba. Reference [
Another study [
The relationship between density (kgm−3) and temperature at all measurement locations (1-19) was inverse relationship (
In general, density values in the RYC’s marina in this study are comparable with values in the Gulf of Aqaba. A previous study [
The analysis of total hydrocarbon samples revealed that the lowest value was 1.404 mg/l at site HC11, and the maximum was 98.56 mg/l at HC9 (
concentrations may be due to the increasing numbers of boats or the site itself that is taking a sample of sea water is in a corner or near the corners. The highest concentrations were found at three locations (HC4 = 65.47 mg/l; HC5 = 66.39 mg/l; HC9 = 96.56 mg/l). In general, the highest concentrations of total hydrocarbon were measured at locations either near corners (HC9) of the RYC’s marina or at the place of cleaning and active anchoring of small ferry vessels (HC4 and HC5).
A justification of the high values at these sites that most of the total Hydrocarbon was gathering in the corners of the RYC. Increasing concentrations of oils usually is due to the intense movement of boats.
There is no published work on total hydrocarbon in the Gulf of Aqaba. A study in Sharm El-Maya bay investigated the Total Petroleum Hydrocarbons in seawater. In the surface water of the bay, TPH
concentrations ranged between 185.6-591.8 ppb with mean value of 351.3 ppb compared to 43.1 ppb at the control site [
The current speed vectors in and outside the RYC’s marina at surface (1 m) revealed that seawater moved outward from the marina into the open sea. Besides, seawater at the bottom (4 m) moved inward the marine from open sea. The difference in the direction of movement at the surface and bottom created exchange system between the marina and open sea. On the other hand, the water movement inside the marina revealed a slight difference between surface and bottom, with weak and non-clear trend. The boundary of the marina controlled the direction of the current inside, which played a good role for enhancing the water exchange with open sea (
The minimum flushing time of seawater inside the RYC’s marina was 1.32 days. This flushing time is acceptable in term of securing a good environmental conditions and avoiding stagnation of seawater in the marina.
The average of residence time in the Ayla lagoons in the northern Gulf of Aqaba during the period June 2012-May 2013 as 2.58 ± 0.66 days [
site | SURFACE | BOTTOM | |||||||
---|---|---|---|---|---|---|---|---|---|
Speed (cm/s) | Direction (˚) | Speed (cm/s) | Direction (˚) | ||||||
Average | STD* | Average | STD | Average | STD | Average | STD | ||
c1 | 1.76 | 0.83 | 215.72 | 49.24 | 1.79 | 0.66 | 203.09 | 57.51 | |
c2 | 1.56 | 0.85 | 53.27 | 42.00 | 1.45 | 0.77 | 41.89 | 42.31 | |
c3 | 1.37 | 0.66 | 282.49 | 51.47 | 1.53 | 0.84 | 345.69 | 46.04 | |
c4 | 0.64 | 0.85 | 59.40 | 53.01 | 2.06 | 0.78 | 21.56 | 56.89 | |
c5 | 2.48 | 1.59 | 183.59 | 34.19 | 1.94 | 0.99 | 138.06 | 43.10 | |
c6 | 4.62 | 2.34 | 48.55 | 61.07 | 4.79 | 2.67 | 12.78 | 63.60 | |
c7 | 2.94 | 1.27 | 147.63 | 52.42 | 1.91 | 1.22 | 176.70 | 45.29 | |
c8 | 2.92 | 2.19 | 112.75 | 25.18 | 2.63 | 2.05 | 158.90 | 18.89 | |
c9 | 1.55 | 0.55 | 137.54 | 41.18 | 1.19 | 0.50 | 134.12 | 45.60 | |
c10 | 2.50 | 1.63 | 306.14 | 52.62 | 2.38 | 1.48 | 270.49 | 58.44 | |
c11 | 3.95 | 2.99 | 28.32 | 51.08 | 4.56 | 1.69 | 26.05 | 51.29 | |
c12 | 6.26 | 3.10 | 100.40 | 47.26 | 6.69 | 3.12 | 253.11 | 46.58 | |
c13 | 3.56 | 1.40 | 145.68 | 52.60 | 2.19 | 1.51 | 232.38 | 46.70 | |
c14 | 8.92 | 3.90 | 330.70 | 44.83 | 7.47 | 2.68 | 329.69 | 47.69 | |
c15 | 6.71 | 2.27 | 140.17 | 59.40 | 5.61 | 2.30 | 138.06 | 58.63 | |
c16 | 6.13 | 2.53 | 247.84 | 56.79 | 5.70 | 2.93 | 113.81 | 61.48 | |
*STD: Standard deviation.
In general, a study [
A non-parametric test (Kruskal Wallis, p < 0.05) was performed for comparison of temperature, salinity and density among sites. The non-parametric test was used since the raw data was non-normal distribution as well as also the comparison was between more than two groups. The comparison test of temperature, salinity and density (
A correlation test among physical properties (temperature, salinity and density) and total hydrocarbon concentration was done in order to estimate the relationship between each parameter with another. The correlation test results manifested a very weak regression coefficient among all parameters, except for temperature vs. density (R2 = 0.78; p = 0.001) and salinity vs. density (R2 = 0.28; p = 0.002).This indicates that there was no correlation between total hydrocarbon and the physical parameters (
The mean values of temperature, salinity and density inside the RYC’s marina were 27.13˚C ± 0.03˚C, 40.51 ± 0.02 psu and 26.83 ± 0.02 kg∙m−3, respectively, which are comparable with open water. Besides, the statistical analysis revealed no significant difference of physical parameter among sites.
There was slightly high concentration of total hydrocarbon at some sites inside the marina, which may affect some aquatic lives. Therefore, it is important to give attention to regular cleaning and maintenance.
The distribution of total hydrocarbon inside the marina might be related to current system and boats’ movements as well as the location reference to the gate.
The residence time of seawater in the marina in this period was 1.32 days. This time is very good for the exchange of water, which helps to mitigate any possible contamination.
The Authors would like to express their thankful for staff of the Marine Science Station/Aqaba and Mote Marine Laboratory/Sarasota-Florida for their help and support to accomplish this work. This work was written and analyzed while a Sabbatical Fellow from The University of Jordan/Aqaba Branch to Riyad Manasrah to be spent at the Mote Marine Laboratory in Florida USA. Fulbright scholarship was also awarded to Riyad Manasrah during this period.
Site | Temperature (˚C) | Salinity (psu) | Density (kg∙m−3) | ||||||
---|---|---|---|---|---|---|---|---|---|
Mean | STD | Mean | STD | Mean | STD | ||||
T1 | 27.003 | 0.018 | 40.444 | 0.011 | 26.824 | 0.014 | |||
T2 | 27.071 | 0.007 | 40.455 | 0.004 | 26.810 | 0.003 | |||
T3 | 27.199 | 0.002 | 40.486 | 0.003 | 26.792 | 0.002 | |||
T4 | 27.109 | 0.009 | 40.440 | 0.003 | 26.786 | 0.004 | |||
T5 | 26.992 | 0.003 | 40.482 | 0.003 | 26.856 | 0.003 | |||
T6 | 26.994 | 0.021 | 40.516 | 0.004 | 26.881 | 0.010 | |||
T7 | 27.120 | 0.014 | 40.491 | 0.003 | 26.821 | 0.006 | |||
T 8 | 27.140 | 0.017 | 40.512 | 0.007 | 26.830 | 0.011 | |||
T 9 | 27.354 | 0.012 | 40.514 | 0.006 | 26.762 | 0.007 | |||
T 10 | 27.109 | 0.003 | 40.508 | 0.003 | 26.837 | 0.003 | |||
T 11 | 27.185 | 0.058 | 40.500 | 0.011 | 26.807 | 0.025 | |||
T 12 | 27.062 | 0.019 | 40.503 | 0.004 | 26.849 | 0.008 | |||
T 13 | 27.361 | 0.015 | 40.346 | 0.017 | 26.633 | 0.018 | |||
T 14 | 27.268 | 0.038 | 40.438 | 0.021 | 26.733 | 0.028 | |||
T 15 | 27.395 | 0.017 | 40.460 | 0.010 | 26.707 | 0.012 | |||
T 16 | 26.894 | 0.257 | 40.567 | 0.058 | 26.952 | 0.084 | |||
T 17 | 27.780 | 0.237 | 40.544 | 0.041 | 26.644 | 0.101 | |||
T 18 | 27.229 | 0.057 | 40.497 | 0.018 | 26.790 | 0.032 | |||
T 19 | 27.264 | 0.046 | 40.513 | 0.017 | 26.791 | 0.023 | |||
Kruskal Wallis Test (Among sites at Surface) | |||||||||
Temperature (˚C) | Salinity (psu) | Density (kg/m3) | |||||||
Chi-Square | 18.000 | 18.000 | 18.000 | ||||||
Degrees of freedom | 18 | 18 | 18 | ||||||
p-value | 0.456 | 0.456 | 0.456 | ||||||
Site | Temperature (˚C) | Salinity (psu) | Density (kg∙m−3) | ||||||
---|---|---|---|---|---|---|---|---|---|
Mean | STD | Mean | STD | Mean | STD | ||||
T1 | 26.931 | 0.021 | 40.486 | 0.009 | 26.879 | 0.013 | |||
T2 | 27.048 | 0.007 | 40.443 | 0.001 | 26.809 | 0.002 | |||
T3 | 27.225 | 0.008 | 40.485 | 0.005 | 26.783 | 0.006 | |||
T4 | 27.036 | 0.016 | 40.469 | 0.013 | 26.833 | 0.015 | |||
T5 | 26.975 | 0.001 | 40.500 | 0002 | 26.875 | 0.001 | |||
T6 | 26.961 | 0.005 | 40.518 | 0.001 | 26.893 | 0.002 | |||
T7 | 27.060 | 0.002 | 40.499 | 0.002 | 26.847 | 0.002 | |||
T 8 | 27.125 | 0.004 | 40.504 | 0.003 | 26.830 | 0.004 | |||
T 9 | 27.090 | 0.003 | 40.503 | 0.002 | 26.840 | 0.002 | |||
T 10 | 27.073 | 0.028 | 40.508 | 0.003 | 26.850 | 0.009 | |||
T 11 | 26.544 | 0.003 | 40.522 | 0.001 | 27.032 | 0.001 | |||
T 12 | 26.947 | 0.143 | 41.002 | 0.284 | 27.264 | 0.225 | |||
T 13 | 27.293 | 0.022 | 40.416 | 0.021 | 26.708 | 0.023 | |||
T 14 | 27.162 | 0.008 | 40.490 | 0.004 | 26.807 | 0.004 | |||
T 15 | 27.390 | 0.009 | 40.503 | 0.017 | 26.742 | 0.015 | |||
T 16 | 26.883 | 0.036 | 40.642 | 0.099 | 27.013 | 0.070 | |||
T 17 | 27.220 | 0.003 | 40.527 | 0.020 | 26.816 | 0.017 | |||
T 18 | 27.111 | 0.012 | 40.572 | 0.030 | 26.885 | 0.019 | |||
T 19 | 27.169 | 0.011 | 40.511 | 0.006 | 26.820 | 0.008 | |||
Kruskal Wallis Test (Among sites at Bottom) | |||||||||
Temperature (˚C) | Salinity (psu) | Density (kg/m3) | |||||||
Chi-Square | 18 | 18 | 18 | ||||||
Degrees of freedom | 18 | 18 | 18 | ||||||
p-value | 0.456 | 0.456 | 0.456 | ||||||
Mann-Whitney test (Surface vs. Bottom) | |||
---|---|---|---|
Temperature (˚C) | Salinity (psu) | Density (kg∙m−3) | |
p-Value | 0.085 | 0.234 | 0.032 |
The authors declare no conflicts of interest regarding the publication of this paper.