MEPS 226:287-300 (2002)  -  doi:10.3354/meps226287

Carbon and nitrogen translocation between seagrass ramets

Núria Marbà1,*, Marten A. Hemminga1, Miguel A. Mateo1, Carlos M. Duarte2, Yvonne E. M. Mass1, Jorge Terrados3, Esperança Gacia3

1Netherlands Institute for Ecology, Centre for Estuarine and Coastal Ecology, Korringaweg 7, 4401 NT Yerseke, The Netherlands
2Grup d¹ Oceanografia Interdisciplinar, IMEDEA (CSIC-UIB) Institut Mediterrani d¹Estudis Avançats, C/ Miquel Marquès 21, 07190 Esporles (Illes Balears), Spain
3Centre d¹Estudis Avançats de Blanes, CSIC, Camí de Santa Bàrbara s/n, 17300 Blanes (Girona), Spain
*Present address: Grupo de Oceanografía Interdisciplinar, IMEDEA (CSIC-UIB) Institut Mediterrani d¹Estudis Avançats, C/ Miquel Marquès 21, 07190 Esporles (Illes Balears), Spain. E-mail:

ABSTRACT: The spatial scale and the magnitude of carbon and nitrogen translocation was examined in 5 tropical (Cymodocea serrulata, Halophila stipulacea, Halodule uninervis, Thalassodendron ciliatum, Thalassia hemprichii) and 3 temperate (Cymodocea nodosa, Posidonia oceanica, Zostera noltii) seagrass species using 13Carbon (13C) and 15Nitrogen (15N) as tracers in experiments conducted in situ. Seagrass leaf and rhizome production during the study period varied from <0.001 to 0.015 gDW shoot-1 d-1 and 0.002 to 0.017 gDW rhizomeapex-1 d-1, respectively. Based on measured leaf and rhizome growth rates, the demand of resources for leaf production varied from 0.19 to 4.99 mgC shoot-1 d-1, and from 0.01 to 0.24 mgN shoot-1 d-1, while the demand for rhizome production varied from 0.62 to 5.57 mgC rhizome apex-1 d-1 and from 0.02 to 0.12 mgN rhizomeapex-1 d-1. Seagrass leaves incorporated the isotopes at rates ranging from 0.04 to 0.63 µg13C gDW-1 h-1, and <0.01 to 0.35 µg15N g DW-1 h-1. After 4 d, all incubated shoots had shared part of the incorporated 13C and 15N with ramets placed at maximum distances ranging from 2.7 (H. stipulacea) to 81 cm (C. nodosa), indicating that seagrass clonal integration may be maintained between 1.6 d (H. stipulacea) and 5.4 yr (P. oceanica). Resource translocation within seagrass clones was stimulated towards horizontal rhizome apices. Seagrass ramets, in 4 d, shared with their neighbours between 0.37 and 390 µg13C and between 0.02 and 178 µg15N. During the study period, resource translocation would supply <5% and up to 40% of the leaf carbon and nitrogen required by a neighbouring developing ramet, respectively, and <5% and up to 36% of the carbon and nitrogen required for rhizome growth; provided that the incorporated resources over 1 d were mobilised at similar rates over 4 d. These results conclusively demonstrate physiological integration between seagrass ramets, and that resource translocation may be an important mechanism for young seagrass ramets to acquire resources and for seagrass clones to expand and persist.

KEY WORDS: Carbon · Nitrogen · Translocation · Seagrass

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