硇洲岛大型海藻群落的季节演替

2011年4月至2012年1月对硇洲岛潮间带大型海藻进行了周年的季节调查,结果表明,调查海域大型海藻共有64种。其中褐藻门15种,占总种类数的23.44%;红藻门28种,占总种类数的43.75%;绿藻门20种,占总种类数的31.25%;蓝藻门1种,占总种类数的1.56%。其种类数春季最多,共43种;夏季24种;秋季29种;冬季31种。有9个物种为4个季节共有种,有14个物种为3个季节共有种。各季节间共有种类数为12~26种,季节间种类更替率为0.42~0.78,春夏季种类更替率最高,秋冬季种类更替率最低。优势种共有13种,仅拟鸡毛菜Pterocladiella capillacea为全年优势种,而半叶马尾藻Sargassum hemiphyllum和小珊瑚藻Corallina pilulifera为3个季节共有优势种。调查海域大型海藻生物量季节变化明显,平均生物量春季最高,冬季次之,夏季最低。不同物种其垂直分带明显,从高潮区往低潮区种类数不断增多;生物量也是从高潮区往低潮区逐渐增大。物种多样性指数变化范围为0.03~2.33,年均值为1.10;均匀度变化范围为0.01~0.70,年均值为0.36;种类丰富度指数变化范围为0.15~1.65,年均值为0.72;辛普森优势度指数变化范围为0.01~0.78,年均值为0.39。各大型海藻含水率变化范围在51.92%~97.52%,平均值为85.21%;总有机碳含量变化范围在4.34%~42.06%,平均为27.99%。相关性分析发现,调查海域大型海藻生物量与无机氮(DIN)呈显著负相关,相关系数为0.49(P<0.05),与其他环境因子的相关性不明显。在大型海藻生长旺盛的冬春季,海水中的无机氮(DIN)含量最低,与其他自然海域冬季营养盐积累规律显著不同。

Seasonal succession of macroalgae community in Naozhou Island

Seasonal investigation of intertidal zones of Naozhou Island was conducted from April 2011 to January 2012. The results show that there were 64 species of macroalgae in this Sargasso field, including 15 species of Phaeophyta, 28 species of Rhodophyta, 20 species of Chlorophyta and one species of Cyanophyta, accounting for 23.44%, 43.75%, 31.25% and 1.56% of the total species, respectively. Among the 64 species, 43 species were thriving in spring, 24 species were emerging in summer, 29 species were active in autumn and 31 in winter. Only nine species were thriving throughout the whole year, including six species of Rhodophyta, two species of Chlorophyta and one species Phaeophyta, while there were 14 species living through three seasons. There were about 12-26 common species that can be found between two seasons and the species turnover rate was from 0.42 to 0.78, associated with higher turnover rates in spring and summer and lower rates in autumn and winter. Moreover, there were 13 dominant species but only Pterocladiella capillacea was the all-year dominant species, while Sargassum hemiphyllum and Corallina pilulifera were the dominant species over three seasons. Average biomass vary greatly with season, with the order of spring (848.14 g·m^-2)＞ winter (378.57 g·m^-2)＞ autumn (297.99 g·m^-2)＞ summer (294.15 g·m^-2). There is clearly vertical variation in the species distribution as the species number increases significantly from high tidal zone to low tidal zone, while the biomass show similar changing trend, indicating both species and biomass increase with water depth in the tidal zone. The Shannon-Weinner index was from 0.03 to 2.33, with an annual average of 1.10, while the Pielou's index was from 0.01 to 0.70, with an annual average of 036; the Margalef index varied from 0.15 to 1.65, with an annual average of 0.72; and the Simpson’s dominance index varied from 0.01 to 0.78, with an annual average of 0.39. The total water content of seaweeds changes ranged from 51.42% to 97.52%, with an average moisture of 85.21%. The total organic carbon content of seaweeds varied from 4.34% to 42.06%, with an average of 27.99%, indicating a strong carbon storage capacity. We find a clear negative correlation between the biomass of large seaweeds and dissolved inorganic nitrogen (DIN), with a coefficient of 0.49 (P＜0.05). The lower DIN of seawater during spring and winter is coincided with microalgae thriving seasons.