Documents Artificial Reefs Coral Reefs Eco half yearly report of Kuwait Environment (Arabic) Eco monthly report of additive June 99 UVABC (Arabic) Electricity in Kuwait Hazardous Waste Disposal Kestrels of Kuwait PET Red Tide (English) Red Tide (Arabic) 1-Eco-Conditions-Information-Copyrights-Trademarks-V2-2002 2-Eco-How to use this CD-V2-2002 3-Eco-Kuwait Environmental Strategy-V2-2002 EIA Booklet Coral Reefs In this report, ECO is shedding the light on corals and coral reefs of Kuwait. Wherever they could be find, coral reefs play an important role in the marine environment. Kuwait's coral reefs are under environmental stress. This stress is due to the lack of proper environmental laws to protect them, unsustainable fishing practices around the Islands, unfriendly diving practices, unsound implementation of projects on the Islands and oil pollution. ECO would like to thank Mr. Shaker Al-Hazeem for his contribution in writing this report. Background to coral bleaching Reef corals generally have a narrow thermal tolerance and live near the upper limit of that tolerance, being adapted to local mean maximum summer temperatures (Jokiel and Coles, 1990). Corals normally contain millions of microscopic single-celled marine plants called zooxanthellae, which use the sun's energy to produce organic carbon energy (glycerol, sugars and amino acids), through the process of photosynthesis (Brown, 1997a). The zooxanthellae have a mutually beneficial relationship with living corals, and provide some of the excess sugars (energy) to the coral polyps, and in return receive some essential inorganic nutrients (ammonium and phosphate ions) from the coral tissue (Fang et al., 1997; Jones, 1997). When reef corals are stressed by unusual natural events or pollutants, the zooxanthellae are lost from the coral tissue in a process known as bleaching, and the coral tissue appears white or fluorescent yellow, pink and blue (the colour of the remaining animal tissue). Bleaching is usually considered to be the initial response to a stress that may eventually kill a coral (Glynn, 1993; Hoegh-Guldberg and Salvat, 1995). Therefore, under severe stress regimes, coral bleaching can be very widespread, and may result in significant death of corals. Consequently, bleaching provides a gauge for grading the responses of corals to natural and un-natural stress. Excessive rains, and unseasonably warm weather resulting from El Nino weather patterns may be responsible for reduced salinity, increased water temperature, and increased ultraviolet light energy (Anonymous, 1996; Davies et al., 1997). These factors can stress reef corals, and cause bleaching events. Bleaching events appear to have been more frequent in the past 20 years compared with previous decades (Brown, 1997a; Brown, 1997b). Glynn (1993) found evidence which suggests that global scale bleaching events are due to elevated sea temperatures and high solar irradiance. There is evidence of increased UV radiation causing a relatively greater loss of zooxanthallae from the more exposed coral tissue layers when compared with the deeper-seated tissues of corals (Brown, 1997a). Ultraviolet (UV) radiation of higher than average intensities penetrates the water column and can trigger coral bleaching (Harriott, 1985; Tudhope, 1992; Davies et al., 1997; Jones, 1997; Jones et al., 1997; Brown, 1997a). After the expulsion of zooxanthellae, coral metabolic activity is weakened, and some corals begin to starve because of their greatly reduced energy supply. This leads to a decline in coral calcification, and may stop growth, impair reproduction, and cause tissue necrosis (Rinkevich and Loya, 1985; Rinkevich, 1989; Muscatine, 1990; Szmant and Gassman, 1990; Kushmaro et al., 1996; Brown, 1997a). A decrease in growth rate could reduce the capacity of corals to compete favourably for space with algal turf, coralline algae, macrophytic algae, sponges and tunicates. Therefore, after temperature stress, coral has less ability to compete with unfavourable microphytic algae that will soon colonise the coral (Lassig et al., 1988; Bell, 1991). The microphytic algae may recruit onto, and colonise, the upper areas of the coral and may grow directly on the live coral tissue, which eventually will die (Meesters and Bak, 1993). During 1982-83, widespread mass coral bleaching occurred in many regions around the world, with more than 70 percent coral mortality in some regions. Mass bleaching was recorded in Australia (GBR) (Fisk and Done, 1985; Oliver, 1985), many reefs in Polynesia, the Thousand Islands in Indonesia, in the Galapagos Islands, Ecuador, in the tropical eastern Pacific Gulf of Panama and Gulf of Chiriqui (Glynn and Croz, 1990; Warwick et al., 1990; Anonymous, 1996; Brown et al., 1996), and in other places around the world including some which have not been documented scientifically (Tudhope, 1992; Grottoli-Everett and Kuffner, 1995; Davies et al., 1997; Jones, 1997; Jones et al., 1997; Brown, 1997a). During the major coral bleaching event recorded in the summer of 1981-1982 on the Great Barrier Reef, Australia, research showed that many coral colonies bleached rapidly, and there was a very patchy and variable rate of coral recovery or death (Fisk and Done, 1985; Harriott, 1985; Oliver, 1985). In some cases, the coral colonies survived, and zooxanthellae gradually returned to the polyp tissues. In many cases, part of the colony died, while other parts survived, while in some reef areas there was widespread death of corals (Tudhope, 1992). At Magnetic Island near Townsville, in the Central Great Barrier Reef region, some areas of the reef slope suffered widespread coral mortality during 1982, and the coral communities have still not recovered after 16 years (P. Harrison, pers. comm.). However, in some other areas new corals have colonised the dead coral skeletons and the reef communities have fully recovered (Jones et al., 1997). Other coral bleaching events were recorded in Jamaica and other Caribbean reefs in 1987-88, where the extent of coral bleaching was studied at two month intervals (Gates, 1990; Goreau and Macfarlane, 1990). In Bermuda, some coral species were studied for their sensitivity to high temperatures (Cook et al., 1990). Different coral species have different sensitivities during bleaching events, and the hydrocoral Millepora alcicornis was the most affected on the transect surveys and the first that significantly recovered. In relation to depth, bleaching was higher on outer reef than on inner reef areas (Cook et al., 1990). During February 1987, there was widespread coral bleaching and death on the Heron Island reef flat. This was reported to be a consequence of dredging (Catterall et al., 1992), however, coral bleaching was also recorded in other regions during this period. Coral bleaching events have also occurred on the fringing reefs of Magnetic Island during the summers of 1979/80, 1986/87, 1991/92 and 1993/94 (Jones et al., 1997). Each of the bleaching events has occurred during periods of unusually high air temperatures, indicating that 'heat waves' cause a warming of the inshore waters and are a contributory factor in bleaching of corals. Significant warming trends have also been observed in the nearby state of Queensland and in eastern Australia over the same periods (Jones et al., 1997). The 1994 coral bleaching event was first recorded on the reefs of Magnetic Island on 16 January 1994, and around four months later (early May 1994) the bleached colonies had regained their normal colouration (Jones, 1997). During February and March 1998, a very severe mass bleaching event occurred on the Great Barrier Reef. At Heron Island, in the Southern Great Barrier Reef region, video transect surveys done at the end of November 1997 showed no evidence of coral bleaching, and normal healthy coral communities were present at all sites (see Chapter 3). Subsequently, widespread bleaching of corals occurred in February 1998, and many inshore reefs in the Central Great Barrier Reef region were heavily bleached (Berkelmans and Oliver, in press). Dr Selina Ward examined areas of the Heron Island reef during March 1998, and found that up to 80% of corals had been bleached, and is monitoring their rates of recovery or mortality. The maximum water temperature recorded on the reef flat by the GBRMPA temperature data loggers was 35.4? C in February 1998. Aims The aim of this study was to quantify the extent of bleaching and recent mortality in coral communities on the north-western area of Heron Island reef during 1998, using quantitative video transects and qualitative visual assessment of coral community attributes in areas adjacent to the transects. The study also sought to analyse any significant temporal changes in these coral reef communities by comparing data from repeated surveys in April 1998 (after the bleaching) with previous 1997 survey data (before the bleaching). Results The results of the April 1998 surveys to assess the extent of bleaching and recent mortality at the study sites showed widespread bleaching of corals on the reef slope, near reef crest, and outer reef flat areas at Heron Island. The results for the video transect surveys for the 8 sites re-surveyed during April 1998 are presented in data on mean percentage cover of benthic categories including bleached benthos are summarised in Table 4.1. During April 1998, bleaching was observed in a wide range of hard corals, some soft corals and in some zoanthids. Three categories of colouration were observed in corals at the survey sites and around the reef area. These were: completely white colonies, partially bleached colonies that displayed a reduced pigmentation, and colonies with normal colouration. The highest mean cover of bleached corals at the study sites was 42.1% recorded north of the harbour at site N2 (Fig. 4.1). The lowest mean cover of bleached coral was 1.1% recorded south of the harbour at site A1, while no bleached corals were recorded in transects at site B1 (Fig 4.1). During April 1998, many of the branching corals such as Acropora pulchra, A. aspera, A. formosa, A. digitifera, and corymbose Acropora were bleached. Some massive corals including Favites sp., Goniastrea, Porites sp. and Goniopora were also bleached. At the survey sites, bleached colonies of plate Montipora, Pocillopora damicornis, and Porites were recorded only at one site. Some colonies of less common species Seriatopora and Fungia were also bleached at the study sites, but were not recorded in the transect analyses. Many of the bleached corals appeared to be starting to recover from bleaching by April 1998, and zooxanthellae were reappearing in their tissues. However, at some sites up to 5-20% of live coral recorded in 1997 seemed to have died very recently, probably as a result of the bleaching. Discussion: Bleaching event physiology studies have shown that coral bleaching can be related to the concentration of, or the loss of, zooxanthella pigment (Gattuso et al., 1991; Jones, 1997). Brown et al. (1995) reported that corals could lose significant quantities of zooxanthallae without discolouring. Colonies of Acropora formosa begin to discolour when they have lost >50% of their zooxanthellae (Brown et al., 1995). Thus coral bleaching is associated with the loss of zooxanthella pigment, either by decreasing the cellular concentration of chlorophyll per zooxanthella or by the expulsion of zooxanthellae. As a result, the coral tissue loses its colour, and colonies turn white because the white skeleton reflects through the tissue. Ecological and physiological research on bleaching of reef corals has stressed the crucial role of elevated temperatures on bleaching (Hoegh-Guldberg and Smith, 1989; Gates, 1990; Glynn, 1993; Brown et al., 1995; Hoegh-Guldberg and Salvat, 1995; Brown et al., 1996; Fang et al., 1997; Jones, 1997; Brown, 1997a). Thus coral bleaching events occur in response to increased sea temperatures and possibly ultraviolet light. Increased levels of ultraviolet radiation have also been suggested as a factor involved in causing mass coral bleaching (Harriott, 1985; Oliver, 1985). Ultraviolet light may act synergistically with temperature to increase the susceptibility of corals to bleaching, and induce the expulsion of the symbiotic zooxanthellae. It has been demonstrated in laboratory experiments that bleaching of corals in shallow waters was induced as a combination of both elevated temperature and high irradiance (Brown, 1997a). Degrees of bleaching, within and among coral colonies and across reef communities, are highly variable and difficult to quantify (Glynn, 1993). Some species are more susceptible to temperature stress and bleaching than others. For example, bleached colonies of Acropora formosa were observed near unbleached Montipora digitata colonies at Heron Island reef in April 1998. Similar patterns were reported by Gleason (1993), who found that there were significant differences in the effect of the bleaching among common coral genera. In February 1998, extensive coral was reported at inshore reefs in the Great Barrier Reef complex (Berkelmans, 1998; Fabricius, 1998; Berkelmans and Oliver, in press), including Heron Island. Similar mass coral bleaching events were reported from various places around the world during 1998, including Lord Howe Island, Western Samoa, Christmas Island, Maldives, Galapagos, Reunion Island, Netherland Antilles, Florida Keys, Yucatan Coast, Cayman Islands, Brazil, Seychelles, Comoro Archipilago, Borneo, California and Panama (Berkelmans, 1998). At Heron Island, water temperatures on the reef flat reached a maximum level of 35.4? C during February 1998 (GBRMPA data; Fig 4.3). Prior to that extreme temperature, other peaks of extreme temperature occurred on December 10, 1997 (33.7? C), December 25, 1997 (34.5? C), January 26, 1998 (34.3? C), February 9, 1998 (33.9? C), and February 23, 1998 (35.4? C) (Fig 4.3). Although extreme temperatures were recorded since early December 1997, coral bleaching was not observed until after the temperature reached 35.4? C on February 23, 1998. The data indicate that water temperature close to 35? C is the critical upper limit of coral resistance for many corals on the reef flat at Heron Island reef. The idea of a critical upper limit of coral resistance is supported by the findings of Fang et al. (1997). They found that coral samples did not start bleaching until a six day exposure to 33? C temperatures (Fang et al., 1997). The water temperature data recorded by the GBRMPA in previous years on the Heron Island reef flat supports the above argument. High water temperatures are always recorded during summer (Fig 4.4). In 1995 and 1996, high temperatures above 30? C frequently occurred during the summer periods from early December until mid-February each year. The ranges of maximum water temperatures recorded during those periods were 31.6-34? C (19/12/95-30/1/96), and 31.9-33.1? C (7/12/96-17/2/97). From January 28 until February 3 1996, maximum water temperatures on the reef flat ranged from 32.1-34? C. However, during the 1995 and 1996 summer periods, no coral bleaching had been recorded at these sites. So far, temperature has been considered as the main factor causing coral bleaching (Hoegh-Guldberg and Salvat, 1995; Davies et al., 1997; Jones et al., 1997; Brown, 1997b; Greenpeace, 1998). A sea surface temperature rise of only 1-2? C above the normal warm season maximum can result in widespread coral bleaching and coral mortality, if the temperature anomaly is sustained for long periods (Tudhope, 1992; McAllister et al., 1994). However, if a temperature rise were sufficiently slow, it may allow corals to adapt to the changing temperature regime (Coles, 1997). Jokiel and Coles (1990) studied the ability of individual corals to adapt to a new elevated temperature regime over a period of a few years. Coral survival at lethal temperatures can be increased somewhat by pre-exposure to temperatures in the upper sub-lethal range. So corals can increase their tolerance to elevated sea temperature and irradiance and become acclimatised in their natural environment (Brown, 1997a). Davies et al. (1997) reported that coral bleaching in Papua New Guinea occurred at the time of the annual maximum monthly sea temperature when long-term sea temperature data sets recorded an anomaly of + 1.29? C. A similar case was reported from French Polynesia, where maximum water temperatures associated with coral bleaching in 1994 were approximately 1.0? C higher than the highest temperatures recorded in 1992 and 1993; years in which bleaching on a massive scale did not occur (Hoegh-Guldberg and Salvat, 1995). Besides temperature, light and/or the combination of light and high water temperature are also suspected as other factors that might cause bleaching (Oliver, 1985; Hoegh-Guldberg and Smith, 1989; Jones, 1997). Hoegh-Guldberg (1989) reported that sudden exposure to full sunlight induced the bleaching of S. pistillata and S. hystrix in laboratory experiments. It is hypothesised that a synergistic effect between high temperature and high light may cause this stress. In this study, the repeated April 1998 field survey was done one to two months after the mass coral bleaching occurred during February and March 1998 at Heron Island reef. As a result, the extent of coral bleaching was lower than observed during February and March 1998, as some of the corals had started to recover, or had died. By April 1998, water temperatures had already decreased, and at the time of sampling the maximum water temperature recorded was 30? C. On the inner reef flat, live coral cover at sites A1 and B1 did not change much before and after bleaching. This indicated that bleaching stress did not severely affect the coral colonies at these sites. The low cover of bleached corals at these sites might be related to the fact that water movements are quite high. Currents flow from the lagoon towards the harbour (see chapter 3 for further explanation), and increase the turnover of water masses at sites A1 and B1. As a result, temperature stress may have been reduced or water temperature at sites A1 and B1 might not have exceeded the critical upper limit of temperature of coral resistance. Dead coral cover increased and other substrata cover decreased in the April 1998 survey compared with 1997. The increase in dead coral may also result from dead coral (caused by bleaching from other sites) being broken off and carried by currents towards the harbour, and ending up at sites A1 and B1. Consequently, the dead coral transferred to these sites would cover the other substrata, and increased the percentage of dead coral cover recorded. Other benthos cover was reduced which contributed to the increased area recorded as substratum. However, the changes in the other benthos such as algal cover could be seasonal changes (Coles, 1988). At site N1 the live coral cover was slightly reduced (approximately 7%) after the bleaching, compared with 1997. This reduction in live coral cover may have resulted from coral mortality due to the bleaching, as water movement at this site is not as strong as in sites A1 and B1 (Fig 4.2). On the outer reef flat, live coral cover decreased at sites A2 and B2 by 17% and 12%, respectively. These changes suggest that bleaching stress and some mortality had occurred at these sites; this hypothesis is supported by the increased proportion of dead coral recorded in April 1998. Data at sites A2, B2, and N2 showed that about 46 to 61% of the live coral was still bleached at the time of the April 1998 survey. The high incidence of bleaching at sites A2 B2 and N2 may have been caused by less extensive water movement compared to the sites in the inner reef flat. At the same time, dead coral cover at sites A2 and B2 increased by 25% and 15%, respectively, and substrata cover decreased by 6% and 3% in both sides. Since water movement at low tide on the outer reef flat is reduced compared with the inner reef flat areas, then the increase in dead coral cover recorded in the transects probably represented local corals that had died. Interestingly, different trends were recorded at site N2 which showed an increase in live coral cover and a decrease in dead coral compared with the 1997 survey (Fig 4.2). During the 1997 surveys, site N2 had the highest live coral cover and was dominated by high density of branching Acropora at the upper limit of growth, limited at low tide by exposure. As the surveys coincided with very low tides, a lot of the Acropora tips appeared to be dead and covered with algae. Thus, the coral tips appeared in the video survey to be dead coral and were recorded as such. Recent research has suggested that coral tissue may survive deep down in the polyps (Meesters and Bak, 1993), and it is possible that some of the coral tips recovered and were able to regrow after the 1997 surveys. Therefore, higher coral cover and less dead coral was recorded in April 1998 compared with the 1997 surveys. Another possibility is that bleaching conditions may have killed the algae covering the tips and the coral appeared to be bleached, not dead. On the reef slope, severe coral bleaching had occurred at site H4 as indicated by the high reduction of live coral (21.9% reduction), whereas in site H1 the reduction was only 2%. The severe bleaching in H4 was also indicated by the higher percentage of bleached coral (46.4%), while in H1 the percentage of bleached coral was only 28.5%. The lower incidence of bleaching in H1 might be related to water movements from the harbour which carry much sediment. The sediment could reduce light penetration, which may have decreased the stress from light at site H1. Overall, the coral communities on the inner reef flat seemed to show less bleaching than those on the outer reef flat and reef slope. The intensity of bleaching on the outer reef flat seemed to be similar to the reef slope, as indicated by the data described above. A possible reason is the increased turbidity at the inner reef flat sites might have reduced the interaction between irradiance and temperature. An alternative is that prior thermal history is involved, such that populations are "adapted" to local conditions; corals developing in an environment with a wider temperature range, such as on inner reef flat, might be less sensitive to temperature variations than those on outer reefs with more exposure to oceanic water (Cook et al., 1990). The effect of the 1998 coral bleaching, as indicated by changes of live coral, bleached coral, and dead coral cover, on Heron Island reef, is comparable to the impacts of a cyclone. Connell et al. (1997) recorded that the 5 cyclones that impacted Heron Island reef during 1967-1992 had caused a maximum reduction of almost 50% of coral cover on the inner and outer reef flat. Similarly in Hawaii, the reduction of coral cover caused by the "Kona" storm was reported to be around 46-10% and most extensive on the reef slope (Dollar and Tribble, 1993). The results of this study have shown that a large reduction in coral cover caused by bleaching occurred mostly in the outer reef flat, while in the inner reef flat no obvious reduction was found. The timing of the April 1998 repeated surveys allowed the extent of bleaching and recent mortality to be quantified at some of the Heron Island reef monitoring sites. However, the full extent of coral mortality from the 1998 bleaching event could not be determined, as many corals remained in a bleached condition during April. Therefore, a continuous monitoring program of the coral communities at Heron Island reef is very important for increasing our understanding of the ecology of the reef in general, and particularly for determining the longer-term significance of the 1998 mass bleaching event on Heron Island reef. Conclusion Both natural stress and human disturbances have affected the coral reef communities at Heron Island. Although the coral communities at the study sites generally showed increased coral cover in 1997 compared with previous surveys, the coral bleaching event in 1998 has inhibited this recovery phase. This natural impact resulted in decreased coral cover and increased dead coral cover in most of the survey sites. The decrease in live coral was most apparent at site A2 where 46% coral mortality occurred between surveys in November 1997 and April 1998. Branching Acropora coral were most severely affected by the bleaching, and showed the highest rates of bleaching and mortality at the study sites. The extent of disturbance to the coral communities at Heron Island caused by the 1998 coral bleaching event, was similar to the disturbance and mortality recorded after cyclones. Regular monitoring of the coral reef for assessing the condition is important to help decision-makers in the management of the reef as a Marine National Park. These case study and it's advancement in having studded history of reef and protected Marine National Park is required to do in the three reef island that Kuwait has as it's marine treasure.