Diversity of symbiotic algae in the genus Symbiodinium in Scleractinian corals of Tanzania

Abstract

With the current increase in frequencies of coral bleaching events, knowledge on genetic diversity of symbiotic algae in the genus Symbiodinium harbored by reef building corals is important in understanding how coral reefs will respond to global climate change. This study was conducted since very little is known about genetic diversity of Symbiodinium harbored by reef building corals from Tanzania. The present study reports the genetic diversity of Symbiodinium sp. in 66 scleractinian coral species from 19 common genera sampled in the Tanzanian coast. Internal transcribed spacer two (ITS-2) region of nuclear ribosomal DNA (rDNA) was used to identify the symbionts types associating with the 66 sampled reef building corals following polymerase chain reaction-denaturing gradient gel electrophresis (PCR-DGGE)-Sequencing approach. ITS-2 Symbiodinium types from clades A, C and D, previously reported in corals from other regions, were detected in this study. Unlike Symbiodinium clade C, sequences of ITS-2 Symbiodinium clade D and A didn’t vary significantly. Most reef building corals were found to have a poor capacity for making symbiosis with multiple symbiotic algae, indicating low adaptability to environmental changes. This study which comes 10 years after the 1998 coral bleaching event gives basic information needed for studies on temporal changes in zooxanthellae diversity in Tanzanian corals, especially in relation to future large-scale bleaching episodes.