Macroalgal assemblage structure on a coral reef in Nanwan Bay in southern Taiwan

Abstract

Four-season surveys of macroalgal assemblage structure on a coral reef in southern Taiwan were performed by transect investigation from October 1999 through August 2000. Species richness increased over time, and percentage cover and biomass peaked in April. Non-metric multidimensional scaling ordination analysis of species similarities between stations showed three distinct clusters corresponding to the upper reef flat, the lower reef flat and the reef slope. The macroalgal assemblage on the lower reef flat was further grouped into two clusters corresponding to the warmer months (October 1999 and August 2000) and the cooler months (January and April 2000), suggesting the macroalgal assemblage is structured primarily by zone and secondarily by season. Species richness, percentage cover, biomass, species diversity (H') and evenness (J') were highest on the lower reef flat, reflecting greater complexity in the macroalgal assemblage in this zone. However, species diversity and evenness on the lower reef flat and the reef slope did not show seasonal variations. Species diversity in the upper reef flat decreased in the warmer months due to the dominance of an unknown red alga in October 1999 and Enteromorpha linza in August 2000. The results of ANO-SIM tests showed that species structure was different not only between zones but also between seasons, and the SIMPER analyses showed that, in the warmer months, Gracilaria coronopifolia, Enteromorpha linza, Laurencia spp. and Hypnea charoides were the species that separated the lower reef flat assemblage from other assemblages. In the same way, the unknown red alga (for Present address: Kaohsiung Municipal Ming-spp., Mastrophora rosea and Portieria hornemannii were the species responsible for differences in structure between the upper reef flat and the reef slope.In the cooler months, the species responsible for differences in structures between the upper reef flat and the other two zones were Sargassum spp., Gracilaria coronopifolia, Enteromorpha linza and Padina australis, and those responsible for differences between the upper reef flat and the reef slope were Hypnea charoides, Halimeda spp., Mastophora rosea, Enteromorpha linza and Portieria hornemannii. The present investigation suggests that macroalgal abundance and structure on a coral reef in Nanwan Bay in southern Taiwan have marked spatial zonation and seasonal variations, and Sargassum on the lower reef flat has become the most abundant alga, as compared to 12 years ago.

Regional and Seasonal Differences in Species Composition and Trophic Groups for Tidepool Fishes of a Western Pacific Island – Taiwan

“…and Enteromorpha spp.) are also more abundant in subtropical Taiwan lending support to this explanation (Tsai et al, 2004). In contrast to our findings, herbivores on coral reefs have been shown to be more abundant as well as account for higher biomass in tropical regions compared to subtropical and temperate regions, despite there being less macroalgae in the tropics (Meekan and Choat, 1997).…”

“…Besides regional differences, only herbivores of tidepool fishes also showed seasonal variations in abundance, biomass and species number (Table 6. ), which might relate to seasonal patterns in the availability of their algal food sources (Tsai et al, 2004). In addition, differences according to site (nested within region) were common for herbivores, planktivores, benthic invertebrate feeders and general carnivores for most, if not all, of the measured dependant variables (abundance, biomass and species number).…”

“…Castellanos-Galindo et al, 2005;Murase, 2013). Indeed, benthic macroalgae and other invertebrates which are food sources for fishes show significant seasonal variation in subtropical and tropical Taiwan (Tsai et al 2004;Shieh and Chi 2010). A closer examination of the diets of intertidal fishes across time may reflect these seasonal patterns.…”

“…Japan and the Philippines, Liu et al, 2008;Chen and Shashank, 2009). The subtidal fish, coral and algal assemblages in Taiwan exhibit seasonal/temporal patterns due to the climatic and oceanic conditions they experience (Kuo et al, 2001;Tsai et al, 2004;Kuo et al, 2012). Whether the species composition and trophic groups of intertidal fish assemblages in northern and southern Taiwan show the same spatial and seasonal patterns as subtidal fish assemblages is yet to be determined.…”

Interannual and Seasonal Changes in the Benthic Algae Flora of Coral Reef in Xiaodong Hai (Hainan Island, China)

“…Investigations of factors influencing seasonal changes in algal species composition in other tropical and subtropical regions do not contradict our results and conclusions. In Nanwan Bay in southern Taiwan (the nearest to Hainan Island), species diversity on the lower reef flat and the reef slope (the low intertidal and upper subtidal zones) showed insignificant seasonal variations [24]. However, essential changes were observed in the intertidal zone of other subtropical and tropical regions.…”