太湖梅梁湾春季浮游植物初级生产力

Phytoplankton Primary Production in Spring Meiliang Bay,Lake Taihu

用黑白瓶测氧法对梅梁湾春季浮游植物初级生产力的变化特征进行研究,探讨了初级生产力的日变化、垂直变化、区域分布、浮游植物现存量与初级生产力的关系以及不同曝光时间对P-I曲线的影响.结果表明,梅梁湾浮游植物初级生产力存在明显的日变化,最大值出现在10:00-14:00;初级生产力在梅梁湾分布呈现为从湾内向湾口逐渐递减的趋势;除表层水受光抑制影响使其生产力相对较低外,初级生产力随水深的增加而降低;初级生产力与叶绿素a存在显著的正相关,用水柱层平均叶绿素a浓度来估算初级生产力比用表层叶绿素a浓度来估算要更为精确;短的曝光时间往往带来高的初级生产力和同化系数.

The variation features of phytoplankton primary production in spring in Meiliang Bay of Lake Taihu is studied by means of dark and light bottle method ( Winkler method). The aim is to study the daily change, vertical profile, region distribution of primary production, the relationship between chlorophyll-a and primary production, and the influence of incubation periods on photo-synthesis-irradiance curves. The results show that primary production of phytoplankton in Meiliang Bay presents a significant daily variation with a maximum during 10:00 - 14:00, accounting for 60% of daily primary production. The value of primary production during a 24h incubation period is largely lower than the sum of a 4h incubation period. It is suitable to calculation the daily total primary production using the value during 10:00 - 14:00. Primary production decreases from inner Meiliang Bay to outer Meiliang Bay due to the difference of chlorophyll-a and concentration of nutrients. Primary production basically decreases with the increase of water depth with an exception at surface layer water due to photoinhibition. A significant positive linear relationship is found between primary production and concentration of chlorophyll-a of surface layer water, concentration of chlorophyll-a in a water column. It is obvious that primary production can be precisely estimated with concentration of chlorophyll-a in a water column. Shorter light incubation time always causes high primary production and assimilation number.