台湾海峡离岛工业区海域浮游生物丰度之长期变化

Time series variation of plankton in a remote industrial island,Taiwan Strait,southwestern Taiwan

本研究利用1993–2010年在云林县台西乡沿岸的8个站位所进行的一年四季近岸10 m及离岸20 m水深的浮游生物调查资料及同步的水质资料,分析了发电厂建成后对浮游生物的影响。本海域18年内浮游生物各类群丰度/密度的各季节平均值,皆以第四季(10–12月)为最低,而各个类群的最高平均值出现的季别并不一致。其中浮游动物出现于第一和第二季(1–6月),浮游植物和虾、蟹幼体在第二季(4–6月),而鱼卵和仔鱼则是在第一至第三季(1–9月)。自2000年第三季起,测线5的测站经常有pH值低于7.8的情形。当该海域水体测得pH值低于7.8时,浮游动物(75±69 ind./m^3)﹑浮游植物((1.60±2.28)×103 cell/L)﹑虾幼体(2.4±5.8 ind./m^3)﹑蟹幼体(1.9±5.0 ind./m^3)及鱼卵(0.88±1.10 ind./m^3)和仔鱼(0.16±0.32 ind./m^3)的丰度/密度值皆偏低,仅为历年总平均值的1/2。据此建议将发电厂排入海洋之水体pH值控制在7.8以上,以降低对浮游生物多样性及丰度的冲击。

Eighteen years of monitoring data at four sections along the coastline of Taisi Township,Yunlin County,between 1993 and 2010 were used to study the effects of power plant on plankton.Sampling was conducted at depths of 10 m and 20 m in each section.Among the four seasons,the fourth quarter（October to December） had the lowest average abundance of plankton over the years.However,the peak abundance of different types of plankton occurred in different seasons.Zooplankton had the highest abundance during the first and second seasons（January to June） while phytoplankton,shrimp larvae and crab larvae had the greatest abundance in the 2nd quarter（April to June） and the peak in fish egg and fish larvae occurred from the 1st to the 3rd quarter（January to September）.Cumulative data from 18 years shows that the pH of SEC5 often dipped below 7.8 since the 3rd quarter of 2000.pH value lower than 7.8 were frequently measured in the stations of section 5.Each time the pH value is under 7.8,the quantities of zooplankton（75±69 ind./m^3）,phytoplankton（（1.60±2.28）×10~3 cell/L）,shrimp larvae（2.4±5.8 ind./m^3）,crab larvae（1.9±5.0 ind./m^3）,fish egg（0.88±1.10 ind./m^3）,and fish larvae（0.16±0.32 ind./m^3） showed significant low values（only the half of the total average）.Accordingly,we strongly suggest that the warm water effluents discharging from a power plant should maintain the pH above 7.8 in the coastal waters to reduce the negative impact on the marine zooplankton biodiversity and abundance.