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

營養鹽、溫度及鹽度是影響東南台灣之台東都蘭灣大型海藻豐度及群聚時間變化的重要因子

鍾愛琪(I-Chi Chung) ； 黃瑞蓮(Ray-Lien Hwang) ； 林欣樺(Sin-Haw Lin) ； 吳宗孟(Tzure-Meng Wu) ； 吳靖穎(Jing-Ying Wu) ； 蘇室維(Shih-Wei Su) ； 陳忠信(Chung-Sin Chen) ； 李澤民(Tse-Min Lee)

《Botanical Studies》 48卷4期 (2007/10) Pp. 419-433

摘要

本研究進行位於東南台灣之台東都蘭灣大型海藻豐度及群聚時間(2001-2003)化與環境因子關係的調查重要因子。共紀錄66種海藻，紅藻為優勢種類。藻類單位面積濕重及乾重隨時間增加而增加，於2003年冬季達最高值，主要是因為傘房龍須菜(Gracilaria coronpifolia)及紅藻與海綿共生之角網藻(Ceratodictyon/Haliclona)大量生長所致。藻類單位面積覆蓋率隨時間而明顯變異，2001及2002年在春季低而夏季高，2003年則在秋季低而在冬、春及夏季高。種類數豐度、歧異度(H')及均勻度(J')隨時間增加而增加，於2001年底的冬季達最高值後於2002年保持不變，2003年下降。不同取樣時間種類相似度之群集分析及無母數多變量向量分析與 ANOSIM(analysis of similarity)分析指出都蘭灣大型海藻群聚主要因年而分群，次為受季節影響而分群，所以海藻群聚在2001至2003年間有極大之變動。雖然H'及J'無明顯隨時間增加而增加或減少的趨勢，k-Dominance curve 結果及隨時間增加而降低之種類數則指出台東都蘭灣大型海藻種類結構由2001年較高歧異度逐漸轉為2003年較低歧異度之群聚。Similarity percentage breakdown procedure (SIMPER)分析證明傘房龍須菜及角網藻是造成群聚年與季節變動的主要海藻種類。群聚與環境因子的比較分析指出可溶性無機磷(soluble-reactive phosphorus; SRP)濃度降低及鹽度升高群聚年變動的主因而影響群聚季節變動的主因則為溫度、降雨、鹽度、及氨態氮。本研究結果指出東南台灣之台東都蘭灣大型海藻群聚之時間(2001-2003)變化不但受隨時間增加而增加之N/P營養鹽比率及增高之鹽度而有年度變動，也受到季節性溫度及降雨變動而有季節性變動，其群聚結構由2001年較高歧異度逐漸轉為2003年較低歧異度狀態。

關鍵字

群聚 ； 大型海藻 ； 營養鹽 ； 鹽度 ； 溫度 ； 時間變異

並列摘要

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 NH(superscript +)4. 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.

並列關鍵字

Assemblage ； Macroalgae ； Nutrient ； Salinity ； Temperature ； Temporal variation