{"refrec":{"BRefID":38536,"RR":"<b>Gras, A.F.; Koch, M.S.; Madden, C.J.</b> (2003). Phosphorus uptake kinetics of a dominant tropical seagrass <i>Thalassia testudinum</i>. <i>Aquat. Bot. 76(4)</i>: 299-315. <a href=\"http://dx.doi.org/10.1016/s0304-3770(03)00069-x\" target=\"_blank\">http://dx.doi.org/10.1016/s0304-3770(03)00069-x</a>","BEntID":38536,"PublicFlag":1,"CheckedFlag":1,"wosflag":1,"vabbflag":null,"RefStringPartII":". <i>Aquat. Bot. 76(4)</i>: 299-315. <a href=\"https://dx.doi.org/10.1016/s0304-3770(03)00069-x\" target=\"_blank\">https://dx.doi.org/10.1016/s0304-3770(03)00069-x</a>","DocTypID":8,"DocType":"Journal article","MarineFlag":1,"FreshFlag":0,"BrackishFlag":0,"TerrestrialFlag":0,"Authorstring":"Gras, A.F.; Koch, M.S.; Madden, C.J.","OrigTitleTranslFlag":0,"Authorstringtrunc":"Gras, A.F. <i>et al.</i>","Englishabstract":"Although nitrogen is primarily the dominant nutrient limiting seagrass production in temperate estuaries, phosphorus (P) limitation can be important in tropical carbonate-dominated seagrass systems. While nitrogen uptake kinetics of seagrasses are moderately well established, very limited data exist on the dynamics of P-uptake. In this study, we determined the kinetics of dissolved inorganic phosphorus (P<sub>i</sub> uptake for a dominant tropical seagrass <i>Thalassia testudinum</i> across a range of P<sub>i</sub> levels (0.5-25 μM). Under this broad range, leaf P<sub>i</sub>-uptake (μmol g<sup>-1</sup> dw h<sup>-1</sup>) rates were similar under light (V<sub>max</sub> = 1.90) and dark (V<sub>max</sub> = 2.10) conditions, while root P<sub>i</sub>-uptake rates declined 30% in the dark, and were significantly lower than leaves under both light (V<sub>max</sub> = 0.57) and dark (V<sub>max</sub> = 0.38) conditions. At lower P<sub>i </sub> concentrations (0.5-5.0 μM), leaf V<sub>max</sub> was 2-3-fold lower (0.50-0.77), while root V<sub>max</sub> was the same at high and low P<sub>i</sub> ranges. Based on linear and non-linear models of P<sub>i</sub>-uptake kinetics for <i>T. testudinum</i>, leaves can contribute a majority of the P sequestered by the plant when surface and porewater P<sub>i</sub> levels are equally low (0.05-0.5 μM). Based on the calculated P-demand of <i>T. testudinum</i> in South Florida, solely root or leaf uptake can account for the P requirements of <i>T. testudinum</i> when porewater or surface water P<sub>i</sub> levels are 0.5 μM. However, when surface and porewater P<sub>i</sub> levels are extremely low (<0.10 μM), such as in Florida Bay and other carbonate seagrass systems where P<sub>i</sub> sequestration by the sediment is highly efficient, even root + leaf P<sub>i</sub>-uptake rates do not meet the P requirements for growth and P-limitation may occur.","AbstractOtherLang":null,"BibLvlCode":"AS","StandardTitle":"Phosphorus uptake kinetics of a dominant tropical seagrass <i>Thalassia testudinum</i>","OrigTitleLangCode":"en","OrigTitleLangCodeExtended":"eng","OrigTitleLangID":15,"DateLastModified":{"date":"2025-07-02 08:33:14.980000","timezone_type":1,"timezone":"+00:00"},"UserAccessRight":null,"UserAccID":null,"AuthorKeywords":"phosphorus; nutrient uptake; seagrass; nutrient cycling; kinetics","OtherDescriptors":null,"Notes":null,"AnaPub":2003,"MonPub":null,"DateUpdate":"2018-05-17","DateCreate":"2003-08-21","SecASFANote":null,"ConfID":null,"PeerRev":1,"VlizCoreFlag":1,"WoScode":"WOS:000184895600004","VABBcode":null,"OpenAcc":1,"DOI":"10.1016/s0304-3770(03)00069-x"},"refs":null,"anarec":{"AnaID":38536,"PubliDate":2003,"Pagination":"299-315","XtraPublOfAnaID":null,"ISBN":null,"Volume":"76","Issue":"4","BRefMon":null,"BRefMonRR":null,"BRefXtra":null,"BRefXtraRR":null,"SerBRefID":42195,"SerRR":"Aquatic Botany. 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