A Comparative Study of the Sensitivity of Fv/Fm to Phosphorus Limitation on Four Marine Algae

Westudiedtheeffectsofnitrogen(N)andphosphorus(P)supplyonFv/Fm(maximalquantumyieldofphotosystemII)inthealgaeChaetocerosdebilis,Dicrateriainornata,PlatymonassubcordiformisandHeterosigmaakashiwotodeterminethesensitivityofFv/FmtoP-limitationofthefourspecies.ObviousdecreaseofFv/FmvaluewasmonitoredinperiodsofP-depletion,thedecreaseshowingdifferentmagnitudesamongalgalspecies.AmorecleardecreaseofFv/FminPlatymonassubcordiformisandHet-erosigmaakashiwowasobserved,comparedwiththatinChaetocerosdebilisandDicrateriainornata.AftertheresupplyofP,theindexFv/Fmofthefourspeciesallrecoveredquicklyin24h.CellpisionwasmaintainedandchlorophyllcontentcontinuedtoincreaseuntiltheendoftheexperimentinPlatymonassubcordiformisandHeterosigmaakashiwo,whileinChaetocerosdebilisandDicrateriainornata,thepisionstoppedinthelaterperiodwhenthegrowthoforganismscameintothestationaryphase.ThemostobviousrespondofchlorophyllcontenttoP-additionswasobservedinHet-erosigmaakashiwoculturein24h.ThesensitivityofFv/Fmtonutrientlimitationsisdifferentamongalgalspecies,andmuchshouldbedonetoimprovetheapplicationofthisindex.