photosynthetic pigmentation and diversity of ... - SOEST Hawaii

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MASTER OF SCIENCE. IN. OCEANOGRAPHY. DECEMBER 2OO4. By. Amy M. Apprill. Thesis Committee: Robert R. Bidigare, Chairperson. Ruth D. Gates.
PHOTOSYNTHETIC PIGMENTATIONAND DIVERSITYOF SYMBIOTIC DINOFLAGELLATES IN LOBATEPORITESSP.CORALS

A THESISSUBMITTEDTO THE GRADUATEDIVISIONOF'THEUNIVERSITY OF HAWAI'I IN PARTIALFULFILLMENTOF THE REQUIREMENTS FORTHE DEGREEOF MASTER OF SCIENCE IN OCEANOGRAPHY DECEMBER 2OO4

By Amy M. Apprill ThesisCommittee: RobertR. Bidigare,Chairperson Ruth D. Gates Eric J. Hochberg

ABSTRACT

Coral bleachingrefersto an observablecolor changein a normally pigmentedcoral causedby a loss of symbiotic algal (: zooxanthellae)pigmentationand/ora loss of the zooxanthellae.Measurementof coral pigmentationis undoubtedlyimportantto monitoring and understandingthesechanges,yet pigment rangesof normally colored coralsare largely unknown. This study developedrobustmethodsto determine photosyntheticpigment concentrationsand examinedquantitativeresponsesto sourcesof variability including depth,coral species,zooxanthellaestrain,and laboratorytreatments of high light, shade,and high temperaturefor the commoncoralsPorite.slobata and, Porites evermannifrom KaneoheBay. Methodsof samplingand extractionwere designedto rapidly preservethe sampleand preventsampleloss prior to analysisby HPLC.

The photosyntheticpigment concentrationsmeasuredusing theserefined methodswere 2-4 fold greaterthan previousreports. The mean (SD) concentrationsfor p. lobata and. P' evermannicombined(n: 80) in decreasing abundance (pg cell-r)were:chlorophylla, 8 . 6 5+ 3 . 3 4 ,p e r i d i n i n , 4 . 4+0r . 7 9 , D D + D T , 2 . 0 2 + 0 . 7 6 4 , d i a d i n o x a n t h( D i nD ) , 1 . 6 3+ 0.660,diatoxanthin (DT), 0.391+ 0.262,chlorophyllc2,0.7g9+ 0.306, 0.346 B_carotene. + 0.155,and dinoxanthtn,0.2Sl+ 0.106. In somecasesthe laboratory treatments extendedminima and maxima of the concentrationranses.

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The greatestsourceof varianceseenherewas due to depth.The trend of depthvariation dependedon the methodof normalizationwith pigment concentrationsincreasingwith depthper zooxanthellerand decreasingwith depthper coral surfacearea. The shallow congenericsP. lobata and P. evermannidisplay variability in their modesof photoacclimationas evidencedby chlorophyll a concentrations,Symbiodiniumspp. subpopulations,and cycling betweenthe xanthophyllsDD and DT. Thesedifferences were not confirmedto originatefrom geneticallydifferent zooxanthellerpopulationsand may be a result of the host light environment.

Cloningthe nr5.8sITS2 regionof the zooxanthellae revealeddiversitywithin singlep. lobata and P. evermannicoloniesthat was not previouslyreportedfor Hawaiian colonies. The zooxanthellaefrom both P. lobata and P. evermannicoloniesappearto representa new groupingof subcladetaxathat is most similarto the C 15 grouping. The cloning approachrevealedan arrayof DNA including multiple zooxanthellaeITS2 types and in somecasescoral iTS2 types within eachsample. There are essentialpathsof future researchregardingthe utility of commonly useddiversity assessment methodsthat need to be addressedbeforerelationshipsbetweenzooxanthellaestrainand pigmentscan be assessed.