Persian gulf is a semi-enclosed marginal sea surrounded by landmasses. It is
located in the subtropical northwest of the Indian Ocean. Corals live in a harsh
condition because of high salinity, fluctuations and long temperature extremes
as well as low tide exposures. Persian Gulf is a shallow sea with an average
depth of about 35 m (Fatemi and Shokri, 2001). The thermal
regime of this shallow Gulf is influenced to a great degree by solar radiation
and wind. Sea temperature normally ranges between 14 to 34°C (Coles
and Fadlallah, 1991).
Kish Island is the first Iranian duty free zone. It occupies 91 km2 and is situated 18 km from the southern most tip of Irans mainland in the Persian Gulf. Kish Island lies between 26°30'N and the 26°35'N and 53°54'E and 54°03'E.
Coral reefs are specialized assemblages that develop in clear, well-lit tropical
and subtropical waters, characterized by great number of organisms (Wood,
1999). They grow on flat substrates (Riegl, 1999),
in a mean sea temperature of 20°C (Coles and Fadlallah,
1991) with a salinity range normally between 32 to 42 ppt (Maghsoudlou,
2008). These ecosystems are sensitive to climate induced changes in their
physical environment (Baker et al., 2008).
Corals bleach under broad range of external stimuli, when these exceed normal
level and become stressful. Stimuli that elicit bleaching include high and low
temperatures, high and low light level, low salinity, sedimentation and general
stress. Under stressful conditions, mechanisms of bleaching include reduction
in the pigment content of zooxantellae and in the density of zooxantellae in
coral tissues (Obura, 2008). Coral bleaching and mortality
have been associated with elevated seawater temperature (Glynn,
In Persian gulf, coral reefs experience long periods of extreme sea temperature
(above 30°C) in summer and low (below 16°C) temperature in winter (Shokri
et al., 2000). However, for the southern parts of Persian Gulf the
cause of coral reef mortality has been reported to be low water temperature
(below 13°C) lasting for a period of days or weeks (Coles
and Fadlallah, 1991). While from our experience and observation, it is clear
that the mortality of corals occurred in northern part of the Persian gulf is
due to long summer with too warm waters observed in Kish Island in 1998 and
In August 2007, coral bleaching occurred in the Northern Persian gulf, while
there were no reports from the south. The extent of bleaching along the Iranian
coastline is unknown, but it affected the Islands of Kish, Farur and Hendorabi,
when mean SSts reached 36.2 and 34.2°C at 10 m depth and remained like this
for about one month (Maghsoudlou et al., 2008).
Figure 1 shows the distribution of the coral reef in Persian
Gulf. They are mostly developed as fringing reefs around Islands (Shokri
et al., 2000) and along a few coastal districts. The healthiest reefs
on the Iranian side are found around Khark and Kharku Islands in the far north
and around the southern Islands, from Lavan to Hormuz (Shokri
et al., 2000).
During two years of effort (Diving and photography), Rezaei
(1996) studied the corals around different Islands of Persian gulf and identified
35 species of hard corals. In this study 12 selected sites were studied and
the presence of soft coral (Sacrophyton), crown-of-thorns star fish (COTs)
in the northern part of Persian Gulf (Tunb-e-Kuchak Island) and of hard coral
(Seriatopora) around Larak Island were all reported for the first time
(Rezaei, 1996). Surveys by Sadeghi
(1997) on the hard corals of Kish Island, identified 19 species. Shokri
investigated coral reefs around Kish Island and reported that approximately
15% of hard corals were bleached (Shokri et al.,
2000). Fatemi and Shokri (2001) studied the coral
reefs around Kish and Farur Islands and Nay Band Bay. They reported 27 species
of hard corals, for Kish Island 21 species of hard corals.
Yellow Band Disease (YBD) in coral reefs around Kish Island is also investigated
(Rezai et al., 2004). Maghsoudlou
et al. (2008) studied bleaching in Larak and Kish Islands and Nay
Band Bay. They reported 15% to 35% coral cover (hard and soft) in these areas.
The family Acroporidea was the most popular, while Favidae and Poritidae occurred
most frequently and Agareciidae and Dendrophyllidae occurred most rarely (Shokri
et al., 2000).
The present study aimed at investigating coral bleaching and evaluating the health condition of the corals.
MATERIALS AND METHODS
This survey carried out in 2 times of the year (May and October 2009) in 2
depths of 3-5 m and 6-10 m. Two Divers swam in constant speed for a set amount
of time in three dive sites, called Persian Gulf seaport station(26°32'
3.6"E, 54°01' 78.6" N) in northeast part of island whereas usage for diving
and boating, Big Coral station (26°30' 3.6" E, 54°02' 64.8" N) east
of island and Jurassic Park station (26°30' 1.3"E, 54°02' 50.5 N) in
front of dolphin park, in southeast of Kish Island whereas to estimate impact
of bleaching in coral reef. Each site distance was 200-250 m from the shore.
For each of the two depths in each site, divers equipped with SCUBA diving equipment
moved slowly every 25 m2 (a total of 200 m2 for each site),
equivalent to a slow walk, for 2 min. After each timed swim the percentage cover
of live and dead coral, substrate and rock were estimated.
|| Map of Kish Island and position of sites from Google earth
|| Categories for estimation of dead coral
|In the present paper the distribution of coral reefs around
Kish Island was determined by the Timed Swim (TS) technique described in
Hill and Wilkinson (2004)
To determine the existence of dead hard corals in different depths, after 8
dive carried out in each site, dead hard corals were estimated according to
indices of categories shown in Table 1.
The air and seawater temperatures were recorded by a mercury thermometer. Figure 2 shows the position of research stations. Statistical analysis was carried out using a one way analysis of variance (One way ANOVA) with SPSS statistical software (Vers.16).
The timed swim survey around the Kish Island showed that most live hard corals
were found on the northeast, the site called Persian Gulf seaport (Fig.
3 and Table 3, 4). Table
2 shows the description of related figures. The greatest percentage of dead
corals was found on Jurassic Park station (Fig. 4 and Table
5, 6). Dead corals in Big Coral site was between Persian
Gulf seaport station and Jurassic Park station (Fig. 5 and
Table 7, 8).
|| Estimate of Persian Gulf seaport, October
|| Estimate of Persian Gulf seaport, May
|| Estimate of Jurassic park site, May
||Percent cover of different substrates in Persian Gulf seaport
site (HC: Hard coral, DC: Dead hard coral, OT: Other, RC: Rock and SD: Sand)
Timed swims on the eastern side of the island showed that normally coral grow
at 4 m deep and more, areas less than 4 m depth were covered by sand. Timed
swim survey at two depth contours 3-5 m and 6-10 at the reef slope at the Persian
Gulf seaport station in May and October, showed alive colonies of Porites
sp., species P. lutea, P. compressa and Cyphastrea microphthalma
had normal growth and were abundant.
|| Estimate of Jurassic park, October
|| Estimate of Big coral site, May
|| Estimate of Big coral site, October
||Percent cover of Different substrates in Jurassic park site.Dead
coral percent was major in this site
||Percent cover of Different substrates in Big coral site
Jurassic Park station, showed abundant dead corals of Acropora sp.,
live corals in reef slope were species like Plathygyra daedalea, Favia
sp. and Porites lutea, Pavona decussate.
||Percent of dead coral in may in big coral site
In Big Coral station great amount of dead coral cover was observed, but it
was less than that of the JurassicPark station. Species seen were Plathygyra
daedalea and Favia sp., Porites lutea, Goniastrea australiensis,
Psammocora contigua, Acanthastrea maxima and P. compressa.
The most diverse coral assemblages were found in Big Coral station, but
healthiest corals were found in Persian Gulf seaport station.
Branching corals (Acropora sp.) were found dead among 3 stations and no sign of recovery was noticed. Alive Acropora sp. was not found in eastern Kish Island. In 2007 bleaching, most Acropora sp. species bleached and since then no live or juvenile Acropora sp. colonies were found around Kish Island. Dead branching coral skeletons were covered by seaweed and filamentous algae, this state observed on Jurassic Park and Big Coral stations too. In October 2009 serious bleaching was not observed and typically coral colonies were healthy.
Red tide of Cochlodinium polykrikoides had occurred in Persian Gulf during the study and it was existed in both studied months with a distant of 1 km from the Coast of Kish Island but was not observed in shallow waters of investigated zones. Despite the presence of red tide, no effect on the corals could be detected, however the consequence of this long lasting red tide and its effected on corals is yet to be investigated.
Figure 3 show average of percent covers of different substrates in Persian Gulf seaport site. Hard coral percent was in high quantity (between 3 stations).
Figure 5 show average of percent covers of different substrates in Big coral site. Rock percent was in high between 3 stations.
Figure 6 show dead coral percent in each dive, dead coral percent was between 20 and 31%.
Figure 7 show dead coral percent in each dive, dead coral percent was between 23 and 52%.
Figure 8 show dead coral percent in each dive, dead coral percent was between 8 and 20%.
||Percent of Dead coral in May in Jurassic park site
||Percent of dead coral in may in persian gulf seaport site
||Percent of dead coral, in October in persian gulf seaport
||Percent of dead coral, in October in jurassic park site
Figure 9 show dead coral percent in each dive, dead coral percent was under 15%.
Figure 10 show dead coral percent in each dive, dead coral percent was between 20 and 40%.
Figure 11 show dead coral percent in each dive, dead coral percent was between 10 and 52%.
||Percent of dead coral, in October in big coral site
In the present study, we looked at survival condition of corals of Kish Island
in east part of the island. According to observations and obtained results,
the diversity of species in Big coral region was more than twice of the other
regions. This is due to high extent of concerned coral zone which provides the
corals with the possibility of a high diversity. There was a high diversity
and low percentage of live corals in Big coral region. According to the observation
was found great colonies of Acropora sp. In this area, after bleaching 2007
and coral mortality branching type of corals constituted high percent of dead
corals. On the other hand because this station has suitable substrate, accumulation
of organisms including Echinometra mathaie (sea urchin) due to presence
of great amount of algae on dead corals and rocks was observed. This species
separates a part of live tissue of coral and causes destruction of corals by
grazing abundant algae on the dead coral (Goldberg and Wilkinson,
2004; Fadlallah et al., 1995) where the live
coral is also present because this bed is more suitable for the aforesaid species
in Big coral station and there is more abundance and destruction is in the greatest
level, but there are reverse conditions in Persian Gulf seaport station. The
percentage of live corals in Jurassic park station was very low (destruction
the sea substrate) and sea bed in this station constituted of gravel and rubble.
This part of the Island is the place where diving boats pass and anchor, therefore
they cause breakage and crushing of corals (specially branching type of corals).
Moreover, the influence of human on Jurassic park station including anchoring
and coastal development and pollution not only impose high stress on corals,
but also has changed organism of the ecosystem.
Considering Fig. 3, the percentage of dead corals in Persian
Gulf seaport station was much less than that of other stations and the higher
cover of live hard corals on the Persian Gulf seaport station is likely due
to the existence of massive (Favia sp.) and sub massive (Porites sp.)
in this area, which are more tolerant to the destructive effects of storms and
human activities(Shokri et al. 2000). Distraction
of corals, especially of branching type, due to the bleaching in 2007 was followed
by alternate weakeing of corals as a result of human-induced and natural pressures
on these ecosystems. Other damages such as bleaching may be the result of either
natural or human induced impacts. Iranian scientists monitored Kish island reef
before and after the bleaching of mid-August 2007 which affected reefs on the
eastern side and probably other parts and finally killed all of the branching
type of corals (Maghsoudlou etal., 2008). Especially
where the sea bed has a shallow slope which made branching corals vulnerable
to high water temperature during low tides. Other corals such as Favia
sp., Plathygyra sp. and favia sp. appear to be more resistant
to temperature stress (Maghsoudlou et al., 2008).
In Persian Gulf seaport station massive and sub massive corals recovery was
noticed and had normally grown but there were no live colony of branching corals
(Acropora sp.) around Kish Island.
Based on the observation, it seems that the causes of reef destruction in Kish
Island fall into two categories, natural impacts and human impacts. The most
severe natural factors threatening the reef corals in this Island are seemingly
storms, bleaching events and extreme environmental conditions, especially the
sudden rise in sea surface temperatures during the mid summer probably due to
global climate change. Human-induced damage includes that resulting from construction
activities along the coast of the island, which is presently under heavy development.
Increasing anchoring, destructive fishing activities i.e. trap fishing, industrial
pollution (Price, 1993), land based pollution from municipal
sewage and probably dolphinarium are other factors threatening the coral reefs.
Corals are in competition with seaweeds for space (Shokri
et al., 2000), the dead corals such as great colonies of Acropora
sp. in Big coral and Jurassic Park stations were completely covered by seaweed.
A light growth of filamentous brown algae covered the dead portion of the corals
(Fadlallah et al., 1995) and their growth could
be enhanced by the increasing input of nutrients in to the sea. Persian Gulf
seaport station showed this state but in low intensity. At Jurassic Park station
water input of dolphin pools increase this state and all of dead branching corals
were covered by seaweed. In Big coral station, nutrients enter into seawater
due to runoff.
The relative importance of factors causing damage to reefs on this Island needs to be studied in more detail and an immediately reduction on diver and boat anchor damage is highly recommended. Mooring bouys should be installed at major reef sites to prevent further anchor damage to coral.
On the other hand, after bleaching in 1996 recovery through coral growth had
already started in Kish island mainly for Acropora species which were damaged
and destroyed during bleaching.
|| Analyze one way ANPVA for 3 stations in May (X<0.05)
|| Analyze one way ANOVA for 3 stations in October (X<0.05)
These corals fast growth (at least 10 cm per year) were observed in 2001 by
Fatemi and Shokri. They suggested that Acropora population would be established
in a few years. But after bleaching in 2007 Acropora species couldnt recover.
The reason for the Acropora disaster of Kish Island is to be investigated in
detail. There is still hope that if certain conservation measure deployed recovery
of the highly valued branching Acropora would occur.
Statically analyze one way (ANOVA) between each station for two different months
(May, October) showed significant difference (x<0.05) (Table
We wish to thank Dr Mohamad Reza Shokri and Dr. Abdullvahab Maghsoudlou, Dr. Rezvan Mossavi for help us with multiple technical tasks.