(N.B. as part of my class in Marine Conservation Ecology, I am asking students to write blogs on their experiences in marine conservation)
By Rebecca Snyder
A group from Columbia’s School of International and Public Affairs participated in a ten day “Environmental Leadership Delegation” to Israel and the West Bank, during which I and my fellow students had the opportunity to hear from a variety of speakers, visit wildlife reserves and learn about local sustainability projects and initiatives. One of our most memorable stops was the Coral Beach Nature Reserve of Eilat, which the Israel Nature and Parks Authority established in 1966. Following a lecture by Dr. Assaf Zvuloni, a local marine ecologist with the Nature and Parks Authority, we had the chance to snorkel along the reef and observe the beautiful array of corals and fish.
Located in the Gulf of Aqaba, Eilat is one of the Northernmost coral reefs in the world. Due to extreme environmental conditions, the reef faces a unique set of natural and anthropogenic challenges as explained by Dr. Zvuloni. The region is characterized by an arid climate, which creates high evaporation rates and, subsequently, very saline waters. 270 species of corals and an additional 2,500 species of marine flora and fauna are present in the reef (Israel Ministry of Tourism). Because the reef straddles the borders of three countries, the politics of conservation efforts can be quite complex.
Eilat’s reefs experienced significant decline in the latter half of the 20th century. This can be attributed to the discharge of raw sewage into the bay combined with the widespread farming of fish in cages, both of which produced an extraordinary excess of nutrients and, subsequently, widespread eutrophication. This decimated both corals and seagrass beds, resulting in the near complete collapse of the reef. Tourism created an additional stressor. Visitors often walked upon the reef and broke pieces of corals off to bring home as souvenirs. Recently, more concerted efforts have been made to eliminate such disturbances to conserve the ecosystem. Fish farming was discontinued in 2008 and sewage discharge was drastically reduced in the mid 90s with the construction of a new sewage treatment plant. A bridge was built out over the inshore reef, to transport divers and snorkelers to the diving area without the need to step directly on the reef. Monitoring of visitor activity has also been stepped up with warnings given over loudspeaker when visitors venture outside of designated swimming/diving areas. The reserve management team is also promoting seagrass beds as potential dive sites to take pressure from tourism off of the reef and educate divers about the importance of seagrass. Despite continuing issues and a wider decline in the world’s coral reef coverage, the prognosis in Eilat is somewhat positive. Diversity, for example, has increased. Seagrass beds have also recovered significantly.
The Red Sea may actually provide a refuge for corals from the threat of coral bleaching. Although maximum sea surface temperatures were exceeded by 2.0 °C in 2010 and 2012, no bleaching was observed in the reserve. As hypothesized by Fine, Gildor and Genin 2013, corals in Eilat may have a higher tolerance for extreme heat events that would normally cause bleaching in other locations due to their migratory history through the very warm southern straits of the Red Sea and settlement in the cooler Gulf of Aqaba, where the reef sits today. Thus corals with genotypes that can withstand such extreme conditions were likely selected for.
However, this does not necessary protect the corals from other heat-related threats. An increase of 0.5°C, for example, can double the prevalence of diseases such as the White Plague Disease (Zvuloni et al., 2015). Conversely, extreme low temperatures can also be problematic in Eilat. Due to ocean circulation, the water temperatures at Eilat don’t fall below 21° C. Nutrients that have been deposited on the seafloor can be disturbed when cold winter temperatures create a temperature inversion and thereby cause a mixing of the water column. This phenomenon led to an extreme eutrophication event in 1992, during which coral 25% of corals died off (Loya, 2004).
Southern storms, which may be exacerbated by climate change, also have the ability to damage the delicate reefs by causing rough seas. Extreme low tides are also a significant issue. Tidal activity is often predictable in much of the world, because the tides are mostly determined by the position of the moon. However, in Eilat the tides are also influenced by the monsoon in Africa, which is much more difficult to predict. To help the corals survive a particularly low tide, reserve staff drove boats along the length of the coral reefs in order to create wakes that would wash water over the exposed corals. However, it occurred to staff that this may cause the coral height to continue to grow and prevent the development of more resilient corals. Also, the species of coral that suffered the most due to low tide was also the most prevalent. Allowing some of these corals to die may allow other species to move in and boost diversity. Luckily, invasive species do not pose a significant threat since the reef is somewhat protected and the temperature and salinity make it difficult for exotic species to thrive. There have been issues with Red Sea species making it through the Suez canal and becoming established in the Mediterranean, however the opposite does not generally occur or is not problematic.
Intensive urbanization of the city of Eilat in Israel, and neighboring city of Aqaba in Jordan, present emerging challenges including light pollution, which can disrupt reproduction. As a key port for oil imports, the threat of a major spill is ever present. Other future issues include the proposed plan to build a canal from the bay of Aqaba up into the Arava valley, from which a new railway system will be constructed to connect the Southern port to the Mediterranean. Such a project would no doubt increase ship traffic and increase sedimentation of the bay.
The Eilat coral reef is unique in more ways than one. Thus, implementing effective conservation initiatives requires a firm understanding of the contextual challenges of the region. Although improvements have recently been observed, continuing disturbances and new plans for further development call into question the future status of the reef.
Fine, M., Gildor, H., & Genin, A. (2013). A coral reef refuge in the Red Sea. Global change biology, 19(12), 3640-3647.
Israel Ministry of Tourism (2016). The Coral Reef in Eilat, Israel. www.goisrael.com.
Retrieved 4 April 2016, from http://www.goisrael.com/Tourism_Eng/Articles/Attractions/Pages/The%20Coral%20Reef%20in%20Eilat.aspx
Loya, Y. (2004). The coral reefs of Eilat—past, present and future: three decades of coral community structure studies. In Coral Health and disease (pp. 1-34). Springer Berlin Heidelberg.
Zvuloni, A., Artzy-Randrup, Y., Katriel, G., Loya, Y., & Stone, L. (2015). Modeling the impact of white-plague coral disease in climate change scenarios. PLoS Comput Biol, 11(6), e1004151.