三疣梭子蟹不同养殖模式池塘叶绿素a的变化特征及粒级结构

2010年6～11月在三疣梭子蟹(Portunus trituberculatus)3种不同养殖模式的池塘中观测了叶绿素a浓度的变化及其粒级结构。结果表明:池塘中叶绿素a浓度变化范围为(5.29±0.13)～(48.00±15.03)mg.m-3,最低值出现在养殖初期6月份,最高值出现在夏季8月份。养殖期间,池塘叶绿素a浓度显著高于港湾和近海。比较3种不同养殖模式的叶绿素a浓度,以"高位池"最高,"底充氧"其次,"增氧机"最低,但叶绿素a浓度的变化规律基本一致,呈现出养殖初期低,然后迅速上升,至8月份达最高值,再缓慢下降。分析认为,在海水养殖生态系统中,叶绿素a浓度主要受环境因子尤其是营养盐浓度分布的影响。三疣梭子蟹养殖池塘中叶绿素a浓度粒级结构表明,Nano-粒级为主要贡献者,平均贡献率达66.9%;Pico-粒级次之,平均贡献率为22.8%;Net-粒级贡献率最小,仅为10.3%。在三疣梭子蟹养殖池塘中,Nano-粒级浮游植物是初级生产力的主要来源,而Pico-粒级光合微生物对初级生产力的作用不容小视。

On the variation and size-fractionated chlorophyll a in ponds with Portunus trituberculatus cultured in different models

The concentration and size-fractionated chlorophyll a in ponds with Portunus trituberculatus cultured in three models were observed from June to November,2010.The results showed that the chlorophyll a concentration range was(5.29±0.13)-(48.00±15.03)mg·m-3;the minimum appeared in June,while the maximum in August.During the culture period,the chlorophyll a concentration in ponds was significantly higher than that of the estuaries and offshore.Among three culture models,the chlorophyll a concentration in "high-intensive pond" was the highest,the next was the "submerged aeration" culture model,and the minimum appeared in the "aeration" culture model.However,the variation of the chlorophyll a concentration was basically the same: in the early period the concentration was low,then rose quickly to the peak in August,and finally slowly declined.After analyzing the marine aquaculture ecosystem,the author found that chlorophyll a concentration was affected mainly by environmental factors,especially nutrient distribution.The size-fractionated chlorophyll a in Portunus trituberculatus ponds showed that the Nanoplankton was the main contributor,the next were Picoplankton and Netplankton,and the average contribution rate was 66.9%,22.8% and 10.3%,respectively.In the Portunus trituberculatus culture pond,the Nanoplankton phytoplankton was the main source of the primary productivity,and the Picoplankton photosynthetic microorganism also played an important role in the primary productivity.