Five Intertidal Areas of the Persian Gulf

30
Intertidal Areas of the Persian Gulf
Sandflat at the western
end of Queshm island with
coral-like calcereous
accretions (ca. 1 m high)
dominated by mussels such
as Melleus regula
(Photo: T. Höpner)
Thomas Höpner, University
Oldenburg, FRG, Hossein
Ebrahimipour, Beheshti
University, Teheran, Iran & S.
M. Kazem Maraschi,
University of Ahwaz, Iran
Wadden Sea Newsletter 2000 - 2
Five Intertidal Areas of the Persian Gulf
Introduction
The Persian Gulf is a tidal sea of the arid-tropical
climate, from the north over the west to the south
surrounded by “wadden” areas. Five of them are
selected to be compared with our temperate “Wadden
Sea” and for an intercomparison within the
Gulf: (1) The coasts of Qeshm island (Strait of Hormuz,
Iran) in the southeast, (2) Kowr-e Mussa in
the north (Iran). (3) Kuwait Bay in the northwest,
(4) Dawhat ad-Dafi in the west (Saudi-Arabia), and
(5) the intertidal flats of the barrier island system
around Abu Dhabi (UAE) in the south (Fig. 1).
The Persian Gulf was a relatively unknown sea
until the second Gulf War of 1990/91. After the terrible
oil spill of 1990/91, it became suddenly a worldwide
disputed sea area, and a rush of examination
and research was triggered, of which the best general
idea is given in a special volume of the Marine
Pollution Bulletin which appeared in 1993 (Price &
Robinson 1993). Information about the Gulf coast
is very different. There are still long stretches such
as the Iranian coast which, as some people say, belongs
to the most unknown coasts of the world,
probably not because of a lack of studies but resulting
from a lack of international publication.
The Gulf´s tidal regime is very complicated. M , 2
S and K constituents with two (M , S ) and one
2 1 2 2
(K ) amphidromal points interfere, producing tidal
2
amplitudes extremely varying in locality and time.
Khowr-e Mussa seems to exhibit the highest amplitudes,
attaining 5 m and more. A general impact
on biological features origins from the interfer-
ence of diurnal and semi-diurnal tides with the
result that the upper intertidal areas are occasionally
dry over several days, exposed to insolation,
heat, evaporation and high salinity and salt
crystallization. While the highest high water line
(HWL) is almost everywhere clearly marked by a
trash line, a mean HWL is hard to be defined. The
same holds for a mean low water line (LWL), while
the lowest LWL is a sharp biological boundary
between the lowest intertidal (occasionally exposed
to the harsh climatic conditions) and the
highest subtidal biocoenoses (permanently protected
by the overlying seawater). This does not
mean that high-lying areas are generally poor in
organisms. There are enough well adapted algae
and animals. It is typical that cyanobacterial mats,
characteristic for extreme conditions, are frequent
in the upper eulittoral and the lower supratidal
zone.
The Five Case Studies
Qeshm. The Iranian island Qeshm is the largest
one of the Gulf, situated in the western part of
the Strait of Hormuz. It is 120 km long and up to
30 km wide. The tidal amplitude is in the range of
2.5 m. Intertidal flats extent mainly along the
northern coastline. The most obvious feature is
the “Hara”, the by far largest mangrove area of
the Gulf, covering approximately 20 km x 20 km,
dissected by a net of tidal channels, and continued
on the opposite mainland.

Qeshm has many different intertidal zones,
sandy, mixed, and muddy, and in the south also
rocky. Many sandy flats are found along the southern
shoreline, which is relatively exposed. Intertidal
flats attain a width of two kilometers and more in
the west and north and exhibit incredible numbers
of macrobenthic individuals on the surface, mainly
mudskippers and large crabs. The lower supratidal
zone around Hara is covered by cyanobacterial mats.
Queshm seems to be a gathering area for migrating
birds before they go back to the North. “Hara
Protected Area”, now a Biosphere Reserve (860 km2 )
of the IUCN Management Category IV and IX, has
this status since 1980 after other protection categories
since 1970. Use is restricted to fishery (mainly
shrimps), occasional boat trips and some mangrove
cutting (for feeding the cattle).
Khowr-e Mussa. The area has been preliminarily
described in this journal by Höpner & Maraschi
(1999). It consists of a basin approximately
the size of the Jadebusen or the Dollard, surrounded
by a corona of numerous tidal creeks of varying
length and width, and the link to the Gulf by a
50 km long estuary-like channel.
Bay of Kuwait. The bay is about 30 km wide
and about 45 km long. The mean tidal amplitude
is in the range of 2 m and about two thirds of the
bay are dry during low water. Intertidal flats of a
width of up to several km stretch mainly along
the northern coast. The muddy character is extreme,
and there are mudflats in the inner part,
which are virtually inaccessible for a walker. The
bay seems to serve as a trap for finest sediments
from the Shatt al Arab.
Mussallamiyah-Dafi Area . Approximately in
1998, the area was selected by the Saudi Arabian
National Commission for Wildlife Conservation
and Development (NCWCD) with the support of
European Scientists and the European Union to
start an international joint ecological research
project with the objective to establish a Marine
Wildlife Sanctuary (Krupp & Jones 1993). The research
results, which were published in one final
(Krupp et al. 1996) and three intermediate reports
and at least 127 original publications make the
area the best described coastal ecosystem of the
whole Gulf. The outstanding property is the unique
concentration of nearly all habitat types of the
western Gulf within a delimited area. On land,
habitats of size and importance are sea-influenced
sabkhas, dunes, salt marshes and limestone cliffs.
In the intertidal zone, cyanobacterial mats, crab
colonies, beachrock flats, mud and sand flats and
some mangrove spots are represented, and these
Kuwait
100 km
48°
Musallamiyah
Dafi
Busheer
Manifah Manifa
Bay
50°
Khowr-e Mussa
Salwah
Bay
Tarut
in many variations. In the subtidal zone, macroalgal
beds, seagrass meadows, coral reefs and mobile
sand bottoms are typical.
Abu Dhabi Barrier Island System. This is clearly
the intertidal area of the highest similarity to the
central Wadden Sea of the southern North Sea.
There are seven barrier islands lined one after the
other in west-east direction. The “Wadden Sea”
behind them has approximately the same size as
ours, but it is dissected by broad tails of the islands
(so-called tomboli). The tidal amplitude is
between one and two meters, and at low water
most of the “Wadden Sea” is exposed. The intertidal
system can be understood by regarding four
aspects, two of which are morphological/geological
and two are ecological/biological: the barrier
islands and the transition of coastal sabkhas to
the intertidal zone is the first pair, and the cyanobacterial
mats and the mangrove areas is the second.
Discussion
The sequence chosen here for the treatment of
the five intertidal areas follows the anticlockwise
main ring-shaped current within the Gulf by which
Queshm is served with fresh oceanic water while
Abu Dhabi receives water after a mean residence
time of about two years in the Gulf. There are so
far no conclusions about a connection between
age or quality of the seawater on the one hand
and the ecological quality of the sites on the other
hand. As the comparative examinations between
the Banc d´Arguin and North Sea flats have
shown, there is no fundamental difference in biomass
density between climatically different intertidal
sediments (Ens et al. 1990).
Intertidal Areas of the Persian Gulf 31
P e r s i a n G u l f
Persian Gulf
Qeshm
Strait of
Hormuz
Strait of
Hormuz
52° 54° 56°
Abu Dhabi
30°
28°
26°
24°
Figure 1: Location of the
five intertidal areas in the
Persian Gulf.
Wadden Sea Newsletter 2000 - 2

32
Intertidal Areas of the Persian Gulf
Seaward mangrove
(Avicennia marina) edge west
of Abu Dhabi. In the
foreground piles of echiuran
Phrashadus pirotansis
(Photo: T. Höpner).
Wadden Sea Newsletter 2000 - 2
Intertidal areas of the Gulf are generally or at
least potentially hypersaline. In the Mussallamiyah-Dafi
area, for instance, all salinities between
45 and saturation could be observed. As a
contrast, in the intertidal zone of Qeshm, salinities
are only around 39 to 42 with single top values
of 45 psu, independently of tide and season
(Ebrahimipour, unpublished). Hence, intertidal research
in the Gulf means hypersaline research, but
a reference of oceanic salinity is available.
The ecological functions which the intertidal
zone has in temperate cases are also found along
the coastline of the Gulf: high primary and secondary
productivity, shelter for reproduction and
development of juveniles, food source for fishes and
birds, diversity of the biotopes as a precondition for
the diversity of the biota. To inhabit intertidal flats
of the harsh climate of the Gulf means still more
adaptation to changing conditions: The temperature
of the sediment surface may increase under
insolation to 60 0C and more even if the sediment
is moist, and salinities may increase until salt crystallizes.
In the temperate climate, moving from the land
over the intertidal zone into the subtidal area does
not mean finding spectacular jumps in productivity.
This is different in the arid zone. The jumps are
still moderate in the cases Khowr-e Mussa and
Qeshm, in the other three cases, deserts with extremely
low productivity border the intertidal zone
very suddenly, and transition zones, such as salt
marsh and cyanobacterial flats, are not always
present. In Khowr-e Mussa, the adjacent terrestrial
zone is generally a humid area, however, of a
considerable salt content. On the shoreline of
Queshm, in many cases a girdle of plants dominated
by Acacia is observed. Kuwait has scarcely
overgrown supratidal areas as well as desert-like
ones. For the other two cases, Mussallamiyah-Dafi
and Abu Dhabi, it is typical that the desert reaches
the highest high water line and that the supratidal
zone by no means has any oasis character.
Only if low-lying supratidal flats are present,
a salt marsh develops. The transition from the
desert to the supratidal area is much more conspicuous
if magroves are present, within the Gulf
area restricted to the single species Avicennia
marina. In both cases, salt marsh and mangrove,
a cyanobacterial mat zone, may smoothen the
transition from the unproductive desert to the
productive supratidal area.
Is such an oasis-like girdle absent, another feature
may mark the transition land-sea and may
cause a jump in the availability of biomass: the trash
line. This accumulation of seaweed, algae, shells and
dead animals is the base of a modest animal community,
mainly insects. Compared with the species
numbers and abundance of the desert, the trash
line (or the several trash lines which originate from
different high water lines) is a special kind of oasis
and a not neglectible component of the intertidal
zone under the arid climate.
The study of the five intertidal areas has the general
result that marked differences are present even
if the areas are situated within the same semi-enclosed
sea. To focus the intercomparison on the
really basic ecological properties and functions, a
principle proposed by Höpner (1998) is applied

which tries to identify “key properties” (Kerneigenschaften).
Qeshm: the key property is the occurrence
of many different intertidal flats in the inflow
of the ocean water into the Gulf. Among them,
the by far largest mangrove forest of the Gulf merits
special attention. Khowr-e Mussa: We assume
that the key property is the corona of innumerable
tidal creeks which create a unique land-sea-transition
zone, and the key function is to provide the
corresponding life conditions. Bay of Kuwait: The
key property is the huge area of exclusively finestgrained
sediments. Mussallamiyah-Dafi : The key
property is the fantastic biotope diversity, covering
special biotopes such as beachrock flats, cyanobacterial
mats and mangrove. Abu Dhabi barrier island
system: the key property is the broad transition
from the sabkha to the intertidal zone, which
means a very flat gradient from absent to rich productivity.
A second question is what functions the selected
intertidal areas have for the Gulf marine ecosystem.
The large unspoiled intertidal flats of Qeshm
may serve the long Iranian coastline with eggs, larvae,
organisms and vegetative material of ocean
quality, a counter-function to Khowr-e Mussa
where the resource may be especially large because
of the tidal creek net. Kuwait Bay may have a distinct,
important function in maintaining the unique
property of the Gulf, which is to be an all-photic
sea. Since this is only possible if the turbidity is low,
the trap for finest sediments may be decisive. To
define corresponding key functions for the last two
intertidal areas is not so easy at hand. The terrible
oil spill of 1991, where most of the oil accumulated
in the Mussallamiyah-Dafi area, points to a possible
trap function for floating matter.
Nature conservation varies from a biosphere reserve
(Qeshm) which protects the Qeshm mangrove
area, over an actually established Marine
Wildlife Sanctuary (Musallamiyah-Dafi) of which,
however, large parts serve as a military training
ground, to mere discussions and good will (the
others).
Challenges: Intertidal research in the Persian/
Arabian Gulf covers the coastline very ununiformly
with focal points at Kuwait, Mussallamiyah/Dafi,
and Abu Dhabi. Research is highly desired for instance
to document natural states before anthropogenic
changes. Despite of catastrophic oil spills,
space consuming industrial development, overgrazing
and overfishing and other impacts, long coastal
stretches are still in a natural condition. The true
ecological functions of the intertidal zone for the
neighboring and remote marine and terrestrial areas
is virtually unknown. The same holds true for
the role of a bird migrating, resting and wintering
region. Aims, methods, and localization of nature
conservation measures are mostly open. There is
still much to do.
References.
Ens, J. B., Piersma, T., Wolff, W. J. & Zwarz, L. (eds.), 1990. Homeward
bound: problems waders face when migrating from the
Banc d´Arguin, Mauretania, to their northern breeding grounds
in spring. ARDEA 78 (1/2).
Höpner, Th., 1998. Tidenküsten. Projektzentrum Ökosystemforschung
an der Univ. Kiel (Hrgb.), Handbuch der Umweltwissenschaften
VI-2.1.10. 1. Erg. Lfg. 5/98. Ecomed Verlag Landsberg.
11 Seiten.
Höpner, Th. & Maraschi, S. M. K., 1999. Intertidal Treasure Khowre
Mussa – unraised. Wadden Sea Newsletter, No. 1, 1999, 3-6.
Krupp, F. & Jones, D. A., 1993. The Creation of a Marine Wildlife
Sanctuary after the 1991 Gulf War Oil Spill. Marine Pollution
Bulletin 27, 315-323.
Krupp, F., Abuzinada, A. H. & Nader, I. A. (eds.), 1996. A Marine
Wildlife Sanctuary for the Gulf Region. European Commission,
Brussels. NCWCD, Riyadh. Forschunginstitut Senckenberg,
Frankfurt. 514 pp.
Price, A. R. G. & Robinson, J. H. (eds.), 1993. The 1991 Gulf War:
Coastal and Marine Environmental Consequences. Marine Pollution
Bulletin 27.
Thomas Höpner
University of Oldenburg
Postfach 2503
D-26111 Oldenburg
hoepner@biologie.uni-oldenburg.de
Hossein Ebrahimipour,
Fac. of Biology, Beheshti-University, Tehran
I.R. Iran
S. M. Kazem Maraschi
Bustan 3rd, Golestan 6th, No. 34
IR – 19847 Tehran - Velenjak
I.R. Iran
Intertidal Areas of the Persian Gulf
33
Wadden Sea Newsletter 2000 - 2