铁限制对浮游植物生长和群落组成的影响研究综述

A review of iron limitation on the growth and competition of phytoplankton

Fe是浮游植物生长必需的微量元素,其供应对水体中浮游植物的生物量、生长速率以及种群组成均具有重要的影响。从Fe在浮游植物新陈代谢中的作用出发,重点对近年来国内外有关Fe对浮游植物光合作用、营养盐吸收利用以及浮游植物群落组成的影响等方面的研究进展作了较详细的介绍,认为:(1)Fe通常是HNLC海域中初级生产力的主要限制因子之一,Fe限制会导致浮游植物细胞色素密度以及相应的光合叶绿素减少,从而降低其光合作用速率,导致生长缓慢;(2)Fe限制还能改变浮游植物吸收营养盐(N、P、Si等)的速率和比例,影响浮游植物的种间竞争,进而影响其群落结构;(3)Fe加富能够改变水体中浮游植物的优势种群,在海洋中表现为硅藻占优势,而在淡水湖泊中则表现为绿藻和细菌占优势;(4)在淡水湖泊中总Fe含量普遍较高,但浮游植物可利用Fe的含量受水体中有机配体的种类和数量的影响,在一定条件下Fe也可能成为浮游植物生长的限制因子,这对进一步认识湖泊水华暴发的机制具有一定的意义;(5)有学者提出将施加Fe作为一种生态手段,来提高HNLC海域的初级生产力,从而缓解由于大气中CO2浓度增加而导致的全球变暖的趋势;相反地,将降低浮游植物可利用Fe含量作为一种生态手段,来控制富营养化湖泊中藻类的生物量及群落结构,从而缓解日益严重的水华问题,值得进一步研究和探讨。

Iron is a trace element necessary for the growth of phytoplankton,and its supply has been suggested to influence phytoplankton biomass,growth rate and species composition.This paper,starting from the roles of iron in phytoplankton metabolism,gives a review of research progresses at home and abroad on the roles of iron in phytoplankton photosynthesis,nutrient uptake and community composition in recent years,and it is suggested that：（1） Iron is usually one of the main limiting factors for the primary production of HNLC areas in the sea,and iron limitation may decrease the content of cytochrome and related photosynthetic chlorophyll in phytoplankton cells,which could reduce its photosynthetic rate and lead to a slow growth rate.（2） Iron limitation may also change both the uptake rate and ratio of nutrients （such as N,P,and Si）,which could affect interspecific competition and the community structure of phytoplankton.（3） Iron enrichment could change the dominant species,which would lead to diatom dominance in the sea,and green algal and bacterial dominances in freshwater lakes.（4） The concentration of total iron in freshwater lakes is usually high,but its availability to phytoplankton is affected by the types and content of organic ligands in the water.Under certain conditions,iron may also be a limiting factor in phytoplankton growth,which may be meaningful for a further understanding of the mechanism of water-bloom outbreak in lakes.（5） Some researchers suggested that iron enrichment may be an ecological approach to increase the primary production of HNLN areas in the sea,which could reduce the trend of global warming caused by increasing CO2 concentration in the atmosphere.On the contrary,one thing may worth further studying and discussing is that it is possible to take the reduction of available iron concentration as an ecological approach to control the biomass and community structure of algae in eutrophic lakes to solve the problems of increasing algal blooms