The Scleractinian Fauna of Yemen: Diversity and Species Distribution Patterns
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Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012 15A Biodiversity and systematics The scleractinian fauna of Yemen: diversity and species distribution patterns Francesca Benzoni1, Michel Pichon2, Eric Dutrieux3, Claude-Henri Chaîneau4, Malek Abdulaziz5 and Ibrahim Al-Thary6 1Department of Biotechnology and Biosciences, University of Milano-Bicocca, Piazza della Scienza 2, I-20126 Milan, Italy 2Museum of Tropical Queensland, Flinders street, Townsville MC, QLD, 4810 Australia & James Cook University Australia, Townsville 3CREOCEAN, Le Belvédère Bât. B, 128 avenue de Fès, 34080 Montpellier, France 4TOTAL DGEP HSE 2 place Jean La Défense 6 - Cedex 45 F-92078 Paris La Défense, France 5Environment Protection Authority, Ministry of Water & Environment Sana’a, Republic of Yemen 6Yemen LNG Company Ltd. P.O. Box 15347, Sana'a, Republic of Yemen Corresponding author: [email protected] Abstract. Hard coral diversity and species distribution in Yemen are thought to be principally controlled by hydrology and hydrodynamic factors acting in the Arabian region. In particular, a strong seasonal upwelling linked to the SW summer monsoon is typically described as a major forcing function prevailing in the Gulf of Aden and Socotra. The diversity of the hitherto little known scleractinian coral fauna of Yemen was investigated through surveys extending from the Kamaran Island area, in the southern Red Sea, to Socotra in the Arabian Sea, and including Aden, Balhaf, Bir Ali, Burum, and Al Mukallah in the Gulf of Aden. Results showed that the scleractinian fauna of the Gulf of Aden is notably different from that of the Yemen Red Sea and from the Socotra Archipelago. More unexpectedly, striking patterns of species and genera distribution and relative frequency were observed along a relatively short stretch of coastline. It is hypothesized that, at the local scale, the synergistic effects of the seasonal upwelling, of fresh water input from major wadi estuaries, and of westward moving eddies in the Gulf of Aden could play a role as for the observed striking coral species distribution patterns. Key words: Yemen, scleractinian corals, distribution patterns, Gulf of Aden, Red Sea, Arabian Sea, Socotra. Introduction These differences have been mainly explained as the Yemen borders three different bodies of water. A result of geologic, climatic, and oceanographic factors shorter section of the country’s coasts faces the Red of the Arabian region (Sheppard et al. 1992). Sea (ca 760 km long) extending from the Saudi The marine climate in Yemen is influenced by the Arabian border in the north to the entrance to the Red Indian Ocean monsoon system (Sheppard et al. 1992). Sea at Bab al-Mandeb in the south (Turak et al. 2007). In the Yemen Red Sea, in the winter winds blow from A longer one (ca 1200 km long) faces the Gulf of the east along the coast of Arabia into the Gulf of Aden extending from the Bab al-Mandeb in the south Aden and are funneled into the Red Sea. During the west to the border with Oman in the north east summer, winds from the northern Red Sea blow to the (Spalding et al. 2001) (Fig. 1). Finally, approximately south along the coast. There, the water temperatures 400 km south of the Yemen mainland, the Socotra range between 30°C offshore to 38°C inshore during archipelago is found in the Arabian Sea. summer with temperatures 5°C cooler in winter Reef corals and coral reefs are known to occur (Turak et al. 2007). The marine climate in the Gulf of along most of the long coastline of Yemen (Spalding Aden and in the Arabian Sea is also dominated by the et al. 2001). The presence of reefs (Sheppard and monsoons affecting the seasonal variations in winds Sheppard 1991), the types of coral communities, and regime. There, the monsoons influence the prevailing the diversity of scleractinian corals (Benzoni et al. currents flowing from south west to north east during 2003; DeVantier et al. 2004; Turak et al. 2007; the summer and reversing during the winter monsoon Pichon et al. 2010) are known to differ in the Yemen (Currie et al. 1973) due to the migration of the Inter- Red Sea, Gulf of Aden, and Arabian Sea coasts. Tropical Convergence Zone (ITCZ) (Sheppard et al. Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012 15A Biodiversity and systematics 1992; Glynn 1993). During the summer monsoon, the Aden coast from Aden (AD, 5 sites), Balhaf (BA, 10 westerly winds blow with strength (over 15 m/sec) sites), Bir Ali (BI, 17 sites) Burum (BU, 10 sites), and along the coast, remove the warm superficial layers of Al Mukallah (MU, 8 sites) (Fig. 1C). water, and cause the upwelling of deeper waters At each site, all scleractinian coral species observed which are cooler and rich in nutrients (Sheppard et al. during a 60 minutes SCUBA dives between 1 and 20 1992). The summer upwelling can lower the water m depth were photographed underwater and their temperature to 16-19°C (Glynn 1993). Moreover, the presence recorded. Digital images were then analyzed increase of nutrients provides more favourable to verify underwater preliminary records and species conditions for the growth of seaweeds and presence records were used to produce a species per phytoplankton rather than reef corals. While some site list. When the species could not be readily species of scleractinian corals, usually flourishing in identified underwater a fragment of the colony was tropical and oligotrophic waters, can live in these collected. Identification to species of the collected extreme pseudo-temperate conditions, the accretion of specimens took place on the basis of skeleton coral reefs is severely reduced (Sheppard et al 1993; morphology using reference literature and, whenever Benzoni et al 2003). possible, original species descriptions and type The Yemen Red Sea coast, and more than 100 material illustrations. islands along it, support different coral communities characterized by a moderately high regional diversity of hermatypic corals including 221 species (Turak et al. 2007). Along the Yemeni coast of the Gulf of Aden, although high cover coral communities (including monospecific coral carpets) have been found (Kemp and Benzoni 1999; Kemp and Benzoni 2000; Benzoni et al. 2003; Richard et al. 2011), the development of coral reefs is limited, and the overall scleractinian coral diversity is of 77 species (Pichon et al. 2012; Stefani et al. 2011). The Socotra Archipelago supports a mix of benthic habitats including coral communities, and the known scleractinian coral diversity is of 253 species (DeVantier et al. 2004). Only recently has the diversity of corals been addressed by detailed studies in different parts of Yemen. However, a comprehensive study of the country’s diversity of scleractinians and of the species distribution patterns has never been undertaken. In Figure 1: A) map of the Indian Ocean showing the position of the this study the published taxonomic inventories and study area in inset B; B) map of Yemen showing the Red Sea and Gulf of Aden coasts of the country, and the position of the Socotra the species distribution data from 81 sites in the archipelago; C) the coastline from Balhaf to Al Mukallah. Lilac Yemen Red Sea, Gulf of Aden, and Socotra rectangles indicate the position of a sampling area. The code for Archipelago are examined together. Moreover, the each sampling area is in bold capital letters close to each lilac distribution of the taxa in the three different bodies of rectangle. KA = Kamaran islands and coast area; AD = Aden; SO = Northern Socotra Island; BA = Balhaf headland; BI = Bir Ali coast water bordered by the country is examined for the and islands; BU = Burum headland; MU = Al Mukallah. first time. Analyses Material and Methods The species presence data set was explored by means of multivariate statistic techniques using PRIMER Sampling statistical package. Hierarchical cluster analysis using Sampling took place at different localities in Yemen Bray-Curtis distance and complete linkage during six different missions between 2007 and 2010 agglomeration algorithm, as well as Principal within the frame of the Total E&P - Creocean - Component Analysis (PCA), were used to explore the University of Milano-Bicocca “Yemen Scleractinia multivariate database and identify groups of sites or Biodiversity Project”. In total, 81 sites were sampled: areas characterized by a similar coral fauna. 16 in an area in the Yemen Red Sea including the Kamaran islands and the coast in front of them (KA, Results Fig. 1B), 15 on the northern coast of Socotra Island (SO, Fig. 1B), and 50 along the north-western Gulf of Proceedings of the 12th International Coral Reef Symposium, Cairns, Australia, 9-13 July 2012 15A Biodiversity and systematics The diversity of scleractinian corals in Yemen Species distribution along the Gulf of Aden coast The species Psammocora albopicta and P. stellata Along the Yemen Gulf of Aden coast, the results of were recorded in the Yemen Red Sea for the first time. the multivariate analyses indicate that the coral These two taxa were also new records in Socotra species presence and relative frequency are different Island together with Caulastrea tumida, Stylophora in Aden, in the Balhaf and Bir Ali sector, and in the madagascarensis, and Coscinaraea wellsi. Overall, Burum and Al Mukallah sector (PCA, Fig. 3). This is taking into account the results of this study and of the the result of rather striking patterns of scleractinian published taxonomic accounts (DeVantier et al. 2004; corals species distribution occurring sharply along a Turak et al. 2007; Pichon et al 2010) 316 species are relatively short stretch of coast (Fig. 1C). Given the recorded from Yemen . small sample size in Aden we concentrated our analyses and discussion mainly on the coast from Coral species distribution in Yemen Balhaf to Al Mukallah (Table 1).