Structure of Benthic Communities along the Taiwan Latitudinal Gradient

Abstract

The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed.

Fig 1. Study area.

The four regions surveyed around Taiwan and locations of study sites.

Fig 2. Sea Surface Temperature (SST) around Taiwan.

Monthly average sea surface temperatures, annual means (red dashed line), and monthly maxima and minima (red shaded area). (a)Northern Coast (1998–2013). (b). Penghu (2007–2013). (c) Eastern coast (2002–2013). (d) Kenting (2007–2013). Data: Central Weather Bureau, Taiwan (http://www.cwb.gov.tw/).

Fig 3. Multivariate pattern.

nMDS ordination showing regional partitioning. Centroids (crosses) were overlaid on the multivariate pattern to represent the relationship between sites and regional dispersion, respectively. OTUs contributing up to 70% of the regional differentiations were added.

Fig 4. Boxplots summarizing, for each region, the distance of transects to regional centroids.

Boxplots display median, first, and third quartiles (hinges); 95% confidence interval of median (notches) and outliers.