Nutrients, temperature, and salinity as primary factors influencing the temporal dynamics of macroalgal abundance and assemblage structure on a reef of Du-Lang Bay in Taitung in southeastern Taiwan

作者：Chung, I Chi; Hwang, Ray Lien; Lin, Sin Haw; Wu, Tzure Meng; Wu, Jing Ying; Su, Shih Wei; Chen, Chung Sin; Lee, Tse Min^*

来源：Botanical Studies, 2007, 48(4): 419-433.

• assemblage
• macroalgae
• nutrient
• salinity
• temperature
• temporal variation

Temporal dynamics (2001-2003) of macroalgal abundance and assemblage structure in relation to environmental variables were studied on a reef in Du-Lang Bay in southeastern Taiwan. Sixty-six species were identified, with rhodophytes as the abundant species. Both the areal wet weight and areal dry weight biomass of total macroalgae increased as time advanced and reached the maximum in the winter of 2003 mainly due to the blooms of Gracilaria coronopifolia and Ceratodictyon/Haliclona, a red alga-sponge symbiose. Macroalgal cover varied temporally, % cover in 2001 and 2002 was low in spring but high in summer while that in 2003 was high in winter, spring, and summer and low in autumn. Species richness (species number), diversity (H') and evenness (J') increased, peaked in the winter in 2001, stabilized in 2002, and then decreased in 2003. The data of hierarchical cluster analysis and non-metric multidimensional scaling ordination of species similarities between different sampling times and the results of an analysis of similarity (ANOSIM) showed that the macroalgal assemblage is structured primarily by year and secondarily by season. Although H' and J' showed fewer changes, the k-dominance curve and a decrease in species number as time advanced suggest a switch of species structure from a highly diversified community to a less diversified one. The similarity percentage breakdown procedure (SIMPER) analysis shows that G. coronopifolia and Ceratodictyon/Haliclona are the species contributing to year-over-year and seasonal differences in species structure. The comparison of macroalgal compositions with environmental variables indicates that decreasing soluble-reactive phosphorus (SRP) concentrations and increasing salinity are the best combination of environment variables to explain the yearly changes in algal compositions. Seasonal variations in species structure were associated with temporal variations in temperature, precipitation, salinity, and NH4+. In conclusion, the nearshore macroalgal assemblage in Du-Lang Bay in Taitung in southeastern Taiwan during 2001-2003 became less diversified over time; the structure is modified yearly by increased nitrogen/phosphorus levels, and salinity and is also affected seasonally by fluctuating temperature and precipitation.

• 出版日期2007-10
• 单位中山大学