Spatial Patterns and Environmental Settings of Non-reefal Coral Communities Across the Tropic of Cancer in the Penghu Archipelago (Pescadores), Taiwan.

Hernyi Justin Hsieh, Colin Kou-Chang Wen, Yuan-Chao Huang, Kao-Sung Chen, Chang-Feng Dai, and Chaolun Allen Chen (2016) Non-reefal coral communities occurring at the edges of scleractinian coral distribution ranges normally show a sharp gradient in the composition of coral species. Environmental and biological factors such as sea surface temperature (SST), competition with other benthos, and human disturbances might play roles in shaping the structure of coral communities. The Penghu Archipelago is located on the east side of Taiwan Strait straddling the Tropic of Cancer and hosts non-reefal coral communities. In this study, benthic surveys throughout the Penghu Archipelago were conducted and potential environmental and biological factors that shape coral species distributions were inferred by multivariate analyses. A total of 103 species representing 28 genera of scleractinian corals were recorded. Three major ecological sectors (northeast, south, and inner) were defined based on a canonical analysis of the principal coordinates of scleractinian species composition. Correlation analyses showed that scleractinians in the south and northeast sectors were strongly influenced by SST-related variables. In contrast, the coral communities in inner sector were mainly affect by turbidity or nutrition, which supposed come from human activities. Distance-based redundancy analysis showed that benthos, except soft corals, hardly interacted with scleractinian coral distributions. Our study demonstrated a distinct coral species assemblage among different islands across the Tropic of Cancer in the Penghu Archipelago. Natural and human-derived environmental factors both showed a strong correlation with coral species distribution. It's clear that either natural and human-derived factors influenced coral composition in Penghu archipelago.