The structure and function of microphytobenthic biofilms

Marine parks and reserves;Deep-sea biology

Consalvey, Mireille ; Paterson, D. M. (David M.) ; Paterson, D. M. (David M.)

University:University of St Andrews

Department:Biology (School of)

关键词: Marine parks and reserves;    Deep-sea biology;   

Others  :  https://research-repository.st-andrews.ac.uk/bitstream/handle/10023/2682/MireilleConsalveyPhDThesis.pdf?sequence=3&isAllowed=y

来源: DR-NTU

【 摘 要 】

Microphytobenthosare the dominantprimary producers on estuarinemudflats playing akeyrolein the functioningof the ecosystem.Studies intomicrophytobenthic ecologyhavepreviouslybeen limited byscalebut the adventoffinescale analysistechniques (gm)as well as non-destructive samplinghasenabled the system to beexamined at alevelnot previously possible.Thisstudyexamined the formation,structure andfunctionof microphytobenthicbiofilmsusing non-destructive(remotesensingby PAM fluorescence; fibreoptic lightmicroprofiling) anddestructive (cryo-freezingandLow temperature scanningelectron microscopy) sampling.Manymicrophytobenthic organisms are motile andhaveevolved complexmigratory strategies.Microphytobenthicmigratory patterns are widelydescribedbutmuch remains to beelucidated about the controllingfactors. The fluorescenceparameterF015 (minimum fluorescenceyield after15minutesdarkadaptation)was used to monitor short-term changes inbiomassat the sediment surface.Light, tidal state, endogeny and combinations thereof were all shown to controlmigration,demonstrating that predictable migratory rhythms cannotbeassumed.Microscalesectioningshowed that chlorophyll a was alwaysconcentratedin the top 400gm(thephotosynthetically activebiomass). Clearmigratory patterns were notdetectedusing microscale sectioning thereforeindicating that migration occurs over a scale < 400gm.Despiteno changes in thechlorophyll a contentin the surfacelayers, LTSEManalysisdemonstrateddiurnal taxonomic shifts providing circumstantial evidence thatmicrophytobenthic cells sub-cycle at the sediment surface to optimisefitness.The lightextinction co-efficient(k)of microphytobenthicbiofilmssignificantly vaned with site, assemblage and also over time. 90%of the surfacePPFD hadalwaysbeenattenuated by 400, and in many cases before 200.Traditionalmicrophytobenthic primary productivity modelsdonot accountforchangesin the spatial and temporal distributionofbiomassorlightattenuation andtherefore their applicability to the real situation maybe limited.