{"refrec":{"BRefID":25908,"RR":"<b>Durako, M.J.; Kunzelman, J.I.</b> (2002). Photosynthetic characteristics of <i>Thalassia testudinum</i> measured in situ by pulse-amplitude modulated (PAM) fluorometry: methodological and scale-based considerations. <i>Aquat. Bot. 73(2)</i>: 173-185. <a href=\"https://dx.doi.org/10.1016/S0304-3770(02)00020-7\" target=\"_blank\">https://dx.doi.org/10.1016/S0304-3770(02)00020-7</a>","BEntID":25908,"PublicFlag":1,"CheckedFlag":0,"wosflag":1,"vabbflag":null,"RefStringPartII":". <i>Aquat. Bot. 73(2)</i>: 173-185. <a href=\"https://dx.doi.org/10.1016/S0304-3770(02)00020-7\" target=\"_blank\">https://dx.doi.org/10.1016/S0304-3770(02)00020-7</a>","DocTypID":8,"DocType":"Journal article","MarineFlag":0,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Durako, M.J.; Kunzelman, J.I.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Durako, M.J.; Kunzelman, J.I.","Englishabstract":"Shoot-to-landscape scale sources of variation in photosynthetic characteristics of <i>Thalassia testudinum</i>, as measured in situ using a submersible pulse-amplitude modulated fluorometer (diving-PAM), were investigated. Shoot-scale variation was assessed to develop a standard-methods protocol for this species. Significant within-shoot and among-shoot scale variation was observed for several PAM-fluorescence parameters. The fraction of incident photosynthetically active radiation (PAR) absorbed by rank 1 (youngest) leaves, 0.67 ± 0.03, was significantly lower than the PAR absorbed by rank 2 and 3 leaves (0.78 ± 0.04 and 0.77 ± 0.04, respectively). Quantum yields (Y) and photosynthetic efficiency (F<sub>v</sub>/F<sub>m</sub>) exhibited greater variability and generally decreased with increasing leaf age (Y =0.78 ± 0.02, 0.78 ± 0.03, and 0.76 ± 0.06 and F<sub>v</sub>/F<sub>m</sub> = 0.79 ± 0.02, 0.77 ± 0.5, and 0.75 ± 0.06 for rank 1, 2, and 3 leaves, respectively). Maximum fluorescence of light-acclimated leaves (F´<sub>m</sub>) significantly decreased from the base to the tip of leaves (1032 ± 203, 1059 ± 139, and 793 ± 107 for the base, middle and tip of the leaf) and Y was significantly reduced from 0.68-0.76 to 0.27-0.62 when measured where leaf lesions were present. However, paired comparisons (with versus without lesions at the tip of the leaf) for the base, middle, and tip areas of rank 2 leaves indicated that lesions effects on photosynthesis were localized only to the area of the lesion (tip). The Y exhibited relatively high variability for short-shoots within seagrass die-off patches and were significantly reduced for short-shoots exhibiting die-off symptoms (rotten leaf base grayish-green leaf color, but no lesions). Negative response slopes for Y and F<sub>v</sub>/F<sub>m</sub>, measured as part of a landscape-scale sampling program, revealed the presence of significant diurnal (time-of-day) and photosynthetic photon flux density (PPFD) related variation, with a more negative slope for Y. These results indicate that the selection of leaf tissue, short-shoot location, and time of measurement need to be considered when determining photosynthetic rates for seagrasses in situ.","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Photosynthetic characteristics of <i>Thalassia testudinum</i> measured in situ by pulse-amplitude modulated (PAM) fluorometry: methodological and scale-based considerations","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2026-06-14 01:31:03.280739","timezone_type":1,"timezone":"+02:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":null,"OtherDescriptors":"PAM fluorometry; Photosynthesis; Seagrasses; Die-off","Notes":null,"AnaPub":2002,"MonPub":null,"DateUpdate":"2002-07-22","DateCreate":"2002-07-22","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":"WOS:000176578000008","VABBcode":null,"OpenAcc":0,"DOI":"10.1016/S0304-3770(02)00020-7"},"refs":null,"anarec":{"AnaID":25908,"PubliDate":2002,"Pagination":"173-185","XtraPublOfAnaID":null,"ISBN":null,"Volume":"73","Issue":"2","BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":42195,"SerRR":"Aquatic Botany. Elsevier Science: Tokyo; Oxford; New York; London; Amsterdam.  ISSN 0304-3770; e-ISSN 1879-1522","StandardTitleSer":"Aquatic Botany","ISSN":"0304-3770","AbbrevSer":"Aquat. Bot.","StandardTitleMon":null,"StartPage":173,"Pages":13,"ToPubliDate":null,"BRefBibLvlCode":"S","SerNotes":null},"monrec":null,"serrec":null,"relations":null,"relationsRev":null,"addrec":null,"othpubs":null,"ownerships":null,"authors":[{"AutName":"Durako","Firstname":"Michael","Initials":"M.J.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":25908,"AutID":7779,"OrderNr":1,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null},{"AutName":"Kunzelman","Firstname":"Jennifer","Initials":"J.I.","Affiliation":null,"Discriminator":null,"CorporateFlag":0,"BEntID":25908,"AutID":28332,"OrderNr":2,"DegrID":null,"EditorFlag":0,"CorrespFlag":0,"IllustratorFlag":0,"ReviserFlag":0,"TranslatorFlag":0,"InsAcronym":null,"InsFSN":null,"ORCID":null,"PersID":null,"InsID":null}],"mapdetails":null,"datasets":null,"monographs":null,"monparts":null,"serparts":null,"BEntOpen":null,"BEntPrivate":null,"availability":null,"litstyles":null,"thespers":null,"arch2discl":null,"SERpubls":[{"PublName":"Elsevier Science","City":"Tokyo; Oxford; New York; London; Amsterdam"}],"MONpubls":null,"pictures":[],"thestermsPath":[{"ThesaurusTerm":"Photosynthesis","ThestID":6173,"Acronym":"ASFA","ThesTermPath":"Chemical reactions > Photochemical reactions > Photosynthesis"},{"ThesaurusTerm":"Sea grass","ThestID":7260,"Acronym":"ASFA","ThesTermPath":"Flora > Weeds > Marine organisms > Seaweeds > Sea grass"},{"ThesaurusTerm":"Fluorimeters","ThestID":3363,"Acronym":"ASFA","ThesTermPath":"Fluorimeters"},{"ThesaurusTerm":"Dielectric constant","ThestID":2308,"Acronym":"ASFA","ThesTermPath":"Properties > Physical properties > Electrical properties > Dielectric constant"}],"thestermsASFA":[{"ThesaurusTerm":"Dielectric constant"},{"ThesaurusTerm":"Fluorimeters"},{"ThesaurusTerm":"Photosynthesis"},{"ThesaurusTerm":"Sea grass"}],"taxtermsASFA":[{"TaxTerm":"Thalassia testudinum"}],"geotermsASFA":null,"collections":null,"conf":null,"proj":null,"Physdatasets":null,"spcols":null,"doi":null,"publs":null,"serparttypes":null,"monauthors":null,"MParts":null,"SParts":null,"hLibs":null,"langs":[{"BEntID":25908,"AbstractFlag":0,"LangID":15,"LangCode":"en","Lang":"English","DutchTerm":"Engels","LangCodeExtended":"eng"}],"urls":[{"URL":"https://dx.doi.org/10.1016/S0304-3770(02)00020-7","externalID":"10.1016/S0304-3770(02)00020-7","URLTypeCode":"DOI","URLID":110641,"URLTypID":13,"URLType":"DOI","URLPrefix":"http://dx.doi.org/"}],"thesterms":[{"ThesaurusTerm":"Dielectric constant","ThestID":2308,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Fluorimeters","ThestID":3363,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Photosynthesis","ThestID":6173,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Sea grass","ThestID":7260,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"}],"taxterms":[{"TaxTerm":"Thalassia testudinum","AphiaID":374720,"TaxtID":22796}],"geoterms":null,"othterms":[{"OtherTerm":"Die-off","OthtID":9594},{"OtherTerm":"PAM fluorometry","OthtID":3941},{"OtherTerm":"Seagrasses","OthtID":4298}],"asfacodes":null,"asfa2codes":null,"thestermsFRIS":[{"ThesaurusTerm":"Dielectric constant","DutchTerm":null,"ThestID":2308,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Fluorimeters","DutchTerm":null,"ThestID":3363,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Photosynthesis","DutchTerm":"Fotosynthese","ThestID":6173,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"},{"ThesaurusTerm":"Sea grass","DutchTerm":"Zeegrassen","ThestID":7260,"Acronym":"ASFA","ThesTypID":1,"ThesType":"ASFA Thesaurus List"}],"taxtermsFRIS":[{"TaxTerm":"Thalassia testudinum","DutchTerm":null,"AphiaID":374720,"TaxtID":22796}],"geotermsFRIS":null,"othtermsFRIS":[{"OtherTerm":"Die-off","DutchTerm":null,"OthtID":9594},{"OtherTerm":"PAM fluorometry","DutchTerm":null,"OthtID":3941},{"OtherTerm":"Seagrasses","DutchTerm":null,"OthtID":4298}],"resmessage":"","complete":1,"sessions":{"newSesName":"Chisala, Chilekwa, C.","newSesDate":{"date":"2002-07-22 12:05:05.193000","timezone_type":3,"timezone":"Europe/Brussels"},"updSesName":"Chisala, Chilekwa, C.","updSesDate":{"date":"2002-07-22 12:05:05.193000","timezone_type":3,"timezone":"Europe/Brussels"}}}