3. SURVEY OF THE GULF OF AQABA IN JORDAN

3.1 RECONNAISANCE SURVEY

An initial reconnaisance survey of the entire coastal region was made which showed that in general, the mountainous terrain is very near the coast line and that the area intervening the same and the sea is very narrow and formed of either rocks or sand. The coast extends from latitude 29°33' N and longitude 35°E, in the north to 29° 17' N and 34° 56°E in the south. The new double lane road runs very near the water line, leaving practically little land between the same and the sea in most places.

A real continental shelf, as is usual in other seas, is not present in the Gulf, the shallow region on the fringe being narrow and leading suddenly to sharp and ravinous depths. The intertidal zone is narrow and is of varying nature at different places, being formed of rooks, coral reefs, gravel or sand. During low tide regimes the coral reefs appear above the water at some regions. The rocks just below the low tide limits are mostly covered with seaweeds. The intertidal fauna appear to be limited in species combination.

The water of the Gulf of Aqaba ia generally calm and clear. However, when the winds set in, the surface becomes rough, the waves being intense in open areas. Different species of corals occur at various depths and are of special attraction to tourists. Many species of coral fishes are encountered among the corals. Juveniles of perches are generally seen to frequent the shallow areas in the northern region of the Gulf.

The mean summer and winter temperatures in Aqaba are 33° and 18° C respectively, the maximum recorded being 47 and the minimum, 1° C. The prevailing winds are north westerly, coming across the rocky mountains and thus keeping the weather dry. The average rainfall is only 38 mm per year. The soil is sandy with saline patches. Natural vegetation is meagre, but many trees and shrubs have been planted, especially in the Aqaba City sector. There are no rivers or canals flowing into the sea.

The northern part of the Gulf experiences considerable human interference due to activities in the port and sport and recreational facilities.

On the basis of information gathered by the reconnaisance survey, further detailed investigations were carried out.

3.2 TYPE OF THE AREA PHYSICAL FEATURES AND NATURE OF INTERTIDAL BIOTA

Jordan has a sea coast of about 24 km in the Gulf of Aqaba, extending up to the new border with Saudi Arabia, at Durrah. The mountains are very near the sea and the most significant feature of the coast line is that it is either rooky or sandy, with gravel and coral reefs predominating at some sectors. The deep waters are very close to the coast, the shallow belt being restricted, sometimes barely 10 m wide. Next to this belt the sea bottom descends to great depths abruptly.

The Gulf of Aqaba is a continuation of the Red Sea towards the north east and has a total length of about 150 km, with an average width of 16 km. The Red Sea has been considered to have originated between the eocene and oligocaene periods, and the south western part of a depression formed between its north end and the Dead Sea is believed to remain as the Gulf of Aqaba (Botros, 1971). The depths on the Jordanian side of the Gulf exceed 1 800 m, the maximum recorded being 1 829 m. The gulf in this region is in the form of a narrow and deep trough.

The entire coastal region in Jordan is more or less arid, with occasional patches of desert vegetation and planted trees and shrubs. The naturally occuring plants belong to the genera Noaea, Artemisea, Achillea, Peganum, Salsola and Haloxylon.

Beginning from the north western boundary, the coastal region has been arbitrarily divided into the undermentioned 8 sectors for the purpose of the present survey (Fig. 1 & 2).

3.2.1 Aqaba City sector - Sector 1

The coastal zone extending from the north western boundary up to the Port has regular habitation and tourist activities. The coast line is more or less sandy, with patches of rocky areas south east of Aqaba hotel and in between the Palm Beach Hotel and the old hospital. Throughout the day considerable amount of traffic and sport activities take place in the sea at this sector.

The important intertidal fauna observed in this sector are: oysters, Patella sp., Chiton sp., small gastropods and seaweeds. Below the water level a large variety of corals with associated fauna comprising of fishes, sea urchins, sea anemones, ascidians, sponges etc. are met with. Many dead corals are encountered in this sector, which indicates adverse effect of human interference on the environment. Juveniles of perches and some small fishes frequent the shallow coastal waters.

3.2.2 The Port area - Sector 2

The coastal region in this sector is completely occupied by the harbour installations and hence is of no direct interest in the present context.

3.2.3 Area south of the Port up to the old boat repair yard at Shryeh - Sector 3

In this sector which is about three km long on the coast, the road runs practically above the water line and on the other side, just at the edge of the mountainous terrain. In view of such conditions, utilization of the coastal land for aquaculture is completely ruled out in this locality. The shallow shelf of the sea is very narrow, extending to about 10 m or even less in many places. Beyond this belt, the sea bottom descends abruptly to great depths.

In the intertidal zone rocks are present at intervals, on which two species of barnacles (Balanus spp.) occur in large numbers. Oysters are scanty, while corals and seaweeds occur in moderate numbers.

3.2.4 Shryeh - Sector 4

In this sector also the road is near the water line, except for about 500 m before the Police Club. However, some stretches of land areas are available between the road and the sea, both at Shryeh and Yamaniyah. The shallow water region is narrow to begin with, but gradually widens and for about 1 km up to the Club a wide area of coral reefs almost reach to the low water level.

Corals are present throughout, with appreciable growth of seaweeds. Barnacles predominate in the intertidal region, with moderate numbers of oysters and other bivalves. Starfishes, sea urchins and gastropods are also common in the shallow areas. Small fishes, juveniles of perches and amphipods are encountered in the sandy areas. In the comparatively deeper waters near the shore, large numbers of brilliantly coloured coral fishes are frequently observed.

3.2.5 Yamaniyah to Abu Gallum - Sector 5

The shore towards the south (beginning from the police club) is sandy for about 500 m, after which rocks, gravel and sand occur at intervals. From about 2 km down the club, the shallow shelf is comparatively wider and harbours many corals, molluscs, echinoderms, sea anemones and weeds.

The intertidal region in this sector shows moderate numbers of barnacles, oysters, mussels, other bivalves, sea anemones and seaweeds. Chiton sp., Patella sp. and amphipods are predominant on the rooks.

3.2.6 Abu Gallum to Hagen Rimt - Sector 6

In the northern portion of this sector, the coastal shelf is narrow, but is wider towards the south. The southern region has large areas of corals which get exposed during low tide periods.

Barnacles predominate on the intertidal rocks, with few Brussels and oysters occuring at intervals. Seaweeds are abundant on the submerged rocks. Chiton sp. and Patella sp. are encountered in intertidal rock pools.

3.2.7 Hagen Hint to Sayeedah - Sector 7

The northern part of this sector has also a narrow shelf of shallow waters, tut towards the south it widens and has an abundance of corals and rocks covered with seaweeds. Many corals get exposed during low water periods. The intertidal region is rocky, sandy and gravelly at intervals.

The intertidal fauna in the northern part is comparatively sparse, with bivalves predominating. However, in the southern portion barnacles are abundant with few oysters and bivalves. Seaweeds are moderately abundant.

3.2.8 Sayeedah, to Durrah - Sector 8

In this sector also the shallow shelf is wider in the southern portion. The intertidal region has long stretches of sand, particularly in the south. Most of the rooks are covered with weeds. The southernmost portion of the sea in this sector is like a bay with comparatively fewer rocks. The intertidal gone here is devoid of appreciable fauna, but seaweeds are present in large quantities in comparatively deeper waters. The last portion of the coast line, about 0.5 k m in length, is rooky and full of corals.

3.3 RAINFALL AND WEATHER CONDITIONS

Aqaba does not experience significant rains. Rainfall and temperature data for the period January 1971 to April 1973 are presented in Table 3.

3.4 TIDAL FLUCTUATIONS

The tide tables for Aqaba give the timings of high waters only. As per Admiralty chart for Gulf of Aqaba, the mean Springs and mean neaps at Aqaba are 106.68 and 99.06 cm respectively above the datum of soundings, which is stated to be approximately mean low water springs during summer season. Earlier reports indicate that the tidal range varies between 60 and 100 cm. The consultant made regular tidal observations at a fixed point near the Palm Beach Hotel and the average daily tidal ranges for the period 29 March to 4 April 1973 are shown. The daily tidal levels at Aqaba are very much influenced by weather conditions. However, the results obtained give a fair idea of the tidal regimes and it would be desirable to make such observations for one complete year. The maximum tidal range during the present study was 94 cm and the minimum, 36 cm. The tidal pattern is more or less of the general type as will be seen from the delineation of typical spring and neap tides in Fig. 4.

Table 3

RAINFALL AND TEMPERATURE RANGES US AQABA

3.5 WATER CHARACTERISTICS

3.5.1 Temperature

The surface temperature in the Red Sea is reported to vary between 18° to more than 30° C (Botros, 1971). The consultant made temperature measurements of the surface water and air at one point and the average weekly maximum and minimum values recorded during day time are given in Table 4. Data on day and night temperatures for the corresponding period of 1971, obtained from the Statistical Year Book, 1971, are also given for the purpose of comparison.

Table 4

WEEKLY AVERAGE TEMPERATURES (°C) DURING APRIL AND MAY

The temperature conditions are satisfactory and favourable for aquaculture purposes. In fact they are comparatively better than those of the inland waters in the country where lower temperatures prevail during three winter months of the year.

3.5.2 Turbidity

The waters of the Gulf of Aqaba are generally crystal clear with visibility extending to several metres. However, on windy days a certain amount of turbidity develops in the shallow coastal areas as a result of the churning action of the waves. Turbidity readings were taken by the consultant on a few such days and the ranges observed are given below:

3.5.3 Hydrogen-ion concentration

Accurate pH measurements could not be made due to the non-availability of a pH meter or Lovibond comparator. Determinations with indicator paper showed that the value varies approximately between 7.2 and 7.5. Such conditions are suitable for aquaculture.

3.5.4 Dissolved oxygen

Dissolved oxygen content of the sea water was determined adopting modified Winkler's method. Samples from the different sectors were analysed and it was observed that the value ranges between 3.8 and 4.4 ppm. Ho appreciable difference was apparent in the dissolved oxygen content of water samples collected from the sane sector early in the morning and at noon.

The dissolved oxygen content, though not very attractive, is sufficient for fish life, provided other environmental conditions are favourable. Under ordinary conditions of temperature and pressure, sea water at saturation point will contain about 7 to 8 ppm of dissolved oxygen. Natural waters often contain much more oxygen during day time due to photosynthetic activity. The abundance of zooplankton in the Gulf (discussed later in this report) may be one of the major factors contributing to the low dissolved oxygen content.

3.5.5 Salinity

Chlorinity of the water was estimated by titration with silver nitrate solution using potassium chromate as indicator and from the readings obtained, salinity values were calculated. The salinity varied between 38 and 41 ppt in the different sectors, Such high salinity values are not favourable to quick growth of fish under controlled conditions.

3.5.6 Total solids

The total solids in a sample of sea water was estimated as 45 557 ppm after drying for 2 hours and 46 970 ppm after 24 hours.

3.5.7 Total hardness

The total hardness of the sea water as CaCO₃ was estimated as 7 370 ppm. (The value for Aqaba city drinking water is about 366 ppm).

More detailed water analyses could not be made due to absence of necessary facilities at Aqaba. Four samples of sea water were sent to Amman, but the determinations could not be made there due to certain technical difficulties.

3.6 PRIMARY PRODUCTIVITY

Four primary productivity determinations were made by the consultant during Nay 1973, adopting the dark and light bottle method'. The values obtained were:

Although more precise determinations are necessary to arrive at definite conclusions, the above results indicate good primary production rates, particularly because of the general deficiency in phytoplankton (described later in this report). The clear water in the sea (vide para 4.52) is not attractive for aquaculture, but since the primary productivity is appreciable, the same need not be a serious handicap.

3.7 SOIL CHARACTERISTICS

As indicated earlier in this report, the soil in the coastal region is generally sandy. A rough trial with a soil sample indicated the presence of about 85 percent sand. The coastal soil has appreciable sodium chloride content* In many areas shrubs and trees have been planted with satisfactory results, which indicates that by repeated flushings the salinity of the soil can be reduced considerably.

The sea bottom in the coastal shallow water areas is formed of corals, rocks, gravel or sand. Organic detritus is found deposited in some areas, particularly in the Aqaba City sector. The soil of rock, gravel and sand is not generally favourable for the bottom culture of oysters.

Detailed soil analyses were outside the scope of the present survey and also were not possible at Aqaba due to lack of facilities.

The sandy nature of the land in the coastal region does not provide favourable conditions for the construction of earthern ponds for fish culture.

3.8 PLANKTON

Plankton collections were made by operating a 0.5 m diameter tow net made of porous muslin cloth. (Bolting cloth was not available locally). The duration of each haul was 15 min under constant slow speed of the boat. All collections were made during the morning hours. Separate observations were made in the four northern sectors for spring and neap tide phases and the results obtained are given in Table 5. The boat could not be taken to the southern sectors and hence the plankton pattern observed in sectors 3 and 4 may be taken to represent the general condition in the area south of the Port.

The plankton data indicate good production rates of zooplankters, especially during the spring tide phases. The phytoplankton production is comparatively low. It is likely that grazing action of the zooplankters is responsible for the low phytoplankton content. The predominant organisms in the plankton are copepods and chaetognaths. Fish eggs and larvae were encountered in few numbers. Among the larvae, eyed larvae of oysters could be distinguished in some collections. Post larvae of shrimps appeared in few numbers only, but their

Table 5

ANALYSIS OF PLANKTON SAMPLES