胶州湾叶绿素a及初级生产力的长期变化

LONG-TERM CHANGES OF CHLOROPHYLL-a CONCENTRATION AND PRIMARY PRODUCTIVITY IN THE JIAOZHOU BAY

采用野外观测与历史数据相结合的方法,系统分析了1984—2008年胶州湾叶绿素a及初级生产力分布格局、季节特征的变化以及长期变化规律。结果表明,近20年来胶州湾叶绿素a的空间分布格局没有发生大的变化,但季节规律发生了很大变化。冬季和夏季叶绿素a浓度升高,春季和秋季叶绿素a浓度下降,使得其双周期型的季节变化特点更为显著。胶州湾叶绿素a浓度的长期变化呈现波动状态,波动范围为1—4.76mg/m3。2月份和8月份叶绿素a的浓度呈现较弱的升高的趋势,而5月份和11月份则表现为下降的趋势。从空间格局上看,湾外区域叶绿素a浓度呈现显著下降的趋势。胶州湾的初级生产力存在一定的年际波动,1980’s、1990’s和2000’s三个时期的季度月平均初级生产力分别为334.41、354.39、347.73mgC/(m2·d),并没有出现下降趋势。

Long-term changes of chlorophyll a（Chl.a） concentration and primary productivity in Jiaozhou Bay during 1984—2008 were studied in this work.The results indicated that there was no significant change on the spatial distribution of Chl.a concentration in the last 20 years.Chl.a concentration showed a decreasing trend from the northeastern and northwestern parts of the Bay to the Bay mouth.Change in the seasonal characteristics of Chl.a concentration was evident,e.g.,it increased in winter and summer,and decreased in spring and autumn,showing a dual-peak feature,especially in the coastal area of the north and the northeast regions of the Jiaozhou Bay.For the longer-term timeframe,Chl.a concentration fluctuated from 1 to 4.76mg/m3 and its concentration showed a weak increasing trend from February and August,and a decreasing trend in May and November.Similar to Chl.a concentration,primary productivity also fluctuated,although no decreasing trend was observed for the long term.Average seasonal primary productivities in the three periods of 1980＇s,1990＇s,and 2000＇s were 334.41,354.39,347.73mgC/（m2·d）,respectively.Long-term changes in Chl.a concentration and primary productivity were affected by both the increased nutrient concentrations and the feeding pressure of maricultured shellfish in the Jiaozhou Bay.