Symbiodinium spp. associated with scleractinian corals from Dongsha Atoll (Pratas), Taiwan, in the South China Sea.

Dongsha Atoll (also known as Pratas) in Taiwan is the northernmost atoll in the South China Sea and a designated marine national park since 2007. The marine park's scope of protection covers the bio-resources of its waters in addition to uplands, so it is important to have data logging information and analyses of marine flora and fauna, including their physiology, ecology, and genetics. As part of this effort, we investigated Symbiodinium associations in scleractinian corals from Dongsha Atoll through surveys carried out at two depth ranges (shallow, 1-5 m; and deep, 10-15 m) in 2009 and during a bleaching event in 2010. Symbiodinium composition was assessed using restriction fragment length polymorphism (RFLP) of 28S nuclear large subunit ribosomal DNA (nlsrDNA). Our results showed that the 796 coral samples from seven families and 20 genera collected in 2009 and 132 coral samples from seven families and 12 genera collected in 2010 were associated with Symbiodinium C, D and C+D. Occurrence of clade D in shallow water (24.5%) was higher compared to deep (14.9%). Due to a bleaching event in 2010, up to 80% of coral species associated with Symbiodinium C underwent moderate to severe bleaching. Using the fine resolution technique of denaturing gradient gel electrophoresis (DGGE) of internal transcribed spacer 2 (ITS2) in 175 randomly selected coral samples, from 2009 and 2010, eight Symbiodinium C types and two Symbiodinium D types were detected. This study is the first baseline survey on Symbiodinium associations in the corals of Dongsha Atoll in the South China Sea, and it shows the dominance of Symbiodinium clade C in the population.

Can resistant coral-Symbiodinium associations enable coral communities to survive climate change? A study of a site exposed to long-term hot water input.

Climate change has led to a decline in the health of corals and coral reefs around the world. Studies have shown that, while some corals can cope with natural and anthropogenic stressors either through resistance mechanisms of coral hosts or through sustainable relationships with Symbiodinium clades or types, many coral species cannot. Here, we show that the corals present in a reef in southern Taiwan, and exposed to long-term elevated seawater temperatures due to the presence of a nuclear power plant outlet (NPP OL), are unique in terms of species and associated Symbiodinium types. At shallow depths (<3 m), eleven coral genera elsewhere in Kenting predominantly found with Symbiodinium types C1 and C3 (stress sensitive) were instead hosting Symbiodinium type D1a (stress tolerant) or a mixture of Symbiodinium type C1/C3/C21a/C15 and Symbiodinium type D1a. Of the 16 coral genera that dominate the local reefs, two that are apparently unable to associate with Symbiodinium type D1a are not present at NPP OL at depths of <3 m. Two other genera present at NPP OL and other locations host a specific type of Symbiodinium type C15. These data imply that coral assemblages may have the capacity to maintain their presence at the generic level against long-term disturbances such as elevated seawater temperatures by acclimatization through successful association with a stress-tolerant Symbiodinium over time. However, at the community level it comes at the cost of some coral genera being lost, suggesting that species unable to associate with a stress-tolerant Symbiodinium are likely to become extinct locally and unfavorable shifts in coral communities are likely to occur under the impact of climate change.

Isolation and characteristics of 10 microsatellite markers from the endangered coconut crab (Birgus latro).

The coconut crab (Birgus latro), an endangered marine-dispersed crustacean, is facing severe and probably accelerating population extinction worldwide, but biological information on its conservation remains deficient. In order to reveal the genetic structure of B. latro, 10 microsatellite loci were developed. A high degree of polymorphism was observed with a mean number of alleles per locus of 16.9. The mean expected heterozygosities were also high, ranging from 0.742 to 0.965. The observed heterozygosities ranged from 0.210 to 0.925. Departures from Hardy-Weinberg equilibrium were observed at five loci after the Bonferroni correction. These hypervariable markers will be utilized to study the genetic diversity and conservation of B. latro throughout its distribution range in the Pacific and Indian Oceans.