鸭绿江口潮间带春季底栖微藻种类和初级生产力研究

Species Composition and Primary Productivity of Microphytobenthos in Intertidal Zone of Yalu River Estuary in Spring

为探明鸭绿江口潮间带底栖微藻对滩涂潜在的贝类生产力的贡献,应用显微镜镜检和叶绿素荧光技术,于2023年3月7—9日对鸭绿江口潮间带底栖微藻种类、丰度、生物量(以叶绿素a含量表征)、脱镁叶绿素a含量、初级生产力水平进行了调查研究。结果表明:该潮间带底栖微藻共鉴定出硅藻和金藻2门29属64种,硅藻占绝对优势,优势种为长菱形藻、舟形藻,底栖微藻的平均丰度为4.01×103个/cm2;沉积物中的叶绿素a和脱镁叶绿素a含量随沉积深度增加而呈递减趋势,但B1、B3、C2和C3站位的叶绿素a垂直分布出现了明显的跃层现象,可能是由生物扰动引起,表层(0~1 cm)沉积物中叶绿素a和脱镁叶绿素a平均含量分别为0.59μg/g和0.93μg/g;从水平分布来看,底栖微藻的种类、丰度和表层生物量分布趋势均为离岸0.5 km>0.1 km>1.0 km,这可能与离岸距离不同的潮区所受的光照时间和底质类型有密切关联;鸭绿江口潮间带底栖微藻初级生产力平均值为16.7 g/(m2·h),由此估算出鸭绿江口潮间带贝类年生产力为9.8万t。由底栖微藻的种类鉴定和初级生产力估算结果可知,春季鸭绿江口潮间带提供的天然饵料种类和数量都适宜开展贝类的增养殖活动。

In order to explore the contribution of benthic microalgae in the intertidal zone of the Yalu River Estuary to the potential shellfish productivity in the tidal mudflat,species composition,abundance,biomass(as characterized by chlorophyll a content),demagnesium chlorophyll a content,and primary productivity were surveyed in the intertidal zone of the Yalu River Estuary on March 7—9,2023 by microscopic technique and chlorophyll fluorescence technique.The results showed that two phyla(Bacillariophyceae and Chrysophyta)were identified including 29 genera and 64 species,with main group of Bacillariophyceae,and the dominant species of Nitzschia longssima and Navicula sp..There was the average microphytobenthos number of 4.01×103 cells/cm 2,with gradual decrease in both chlorophyll a and phaeophytin a with the increase in mudflat sediments,and several observed leaps in the vertical distribution of chlorophyll a in B1,B3,C2 and C3 stations,which might reflect the effects of bioturbation.There was mean concentrations of 0.59μg/g for chlorophyll a and 0.93μg/g for phaeophytin a in the top centimeter of sediment(0—1 cm).The descending order of species composition,abundance,and surface biomass distribution trends of microphytobenthos were expressed as 0.5 km>0.1 km>1.0 km offshore in horizontal distribution,which might be closely associated with photoperiod and sediment types of tidal areas in different offshore distances.The average primary productivity of microphytobenthos was estimated to be 16.7 g/(m 2·h),and the annual productivity of shellfish to be 9.8×104 tons in the intertidal zone of the Yalu River Estuary,indicating that the natural food types and quantities provided by the intertidal zone of the Yalu River Estuary were suitable for the cultivation of shellfish in spring.