[en] A one-year in situ experiment using N-15 as a tracer was designed to assess the N recycling in the leaves of the seagrass Posidonia oceanica (L.) Delile. R oceanica was shown to partly recycle the internal nitrogen pool of its leaves in order to contribute to new leaf growth. The leaves sampled in June 1999 contained 20% of the quantity of N-15 found in June 1998. N recycling caused a difference between N and biomass turnover rate (0.8 vs 1.3 y(-1)) of Posidonia leaves. This 40% difference should correspond to the contribution of recycled N to the annual N requirement of Posidonia leaves. The N recycling appears to be insufficient to significantly reduce the quantitative impact of N loss due to autumnal leaf fall. However, new leaf growth between June and October is mainly sustained by this recycling because the tracer concentration in new leaves was the same as in the other leaves. By contrast, tracer concentration decreased drastically between October 1998 and June 1999, showing the more important contribution of N uptake during winter and spring. Nevertheless, recycling occurs throughout the year as demonstrated by the presence of tracer in the youngest leaves of shoots sampled one year after the tracer addition. (C) 2002 Elsevier Science B.V. All rights reserved.
Research center :
MARE - Centre Interfacultaire de Recherches en Océanologie - ULiège
Alcoverro, T., Duarte, C.M., Romero, J., 1995. Annual growth dynamics of Posidonia oceanica: Contribution of large scale versus local factors to seasonality. Mar. Ecol. Prog. Ser. 120, 203-210.
Alcoverro, T., Manzanera, M., Romero, J., 2000. Nutrient mass balance of the seagrass Posidonia oceanica: The importance of nutrient retranslocation. Mar. Ecol. Prog. Ser. 194, 13-21.
Bay, D., 1984. A field study of the growth dynamics and productivity of Posidonia oceanica (L.) Delile in the Calvi bay, Corsica. Aquat. Bot. 20, 43-64.
Borum, J., Murray, L., Kemp, W.M., 1989. Aspect of nitrogen acquisition and conservation in eelgrass plants. Aquat. Bot. 35, 289-300.
Dalla Via, J., Sturmbauer, C., Schönweger, G., Sötz, E., Mathekowitsh, S., Stiffer, M., Rieger, R., 1998. Light gradients and meadow structure in Posidonia oceanica: Ecomorphological and functional correlates. Mar. Ecol. Prog. Ser. 163, 267-278.
Dauby, P., Poulicek, M., 1995. Methods for removing epiphytes from seagrasses: SEM observations on treated leaves. Aquat. Bot. 52, 217-228.
Frankignoulle, M., Bouquegneau, J.-M., 1990. Daily and yearly variations of total inorganic carbon on a productive coastal area. Est. Coast. Shelf Sci. 30, 79-89.
Gobert, S., Belkhiria, S., Dauby, P., Havelange, S., Soullard, M., Bouquegneau, J.-M, 1995. Variations temporelles de la phénologie et de la composition biochimique de la phanérogame marine Posidonia oceanica en baie de Calvi. Bull. Soc. Roy. Sci. Liège 64, 263-284.
Gobert, S., Defawe, O., Lepoint, G., Demoulin, V., Bouquegneau, J.-M., 2001. Anthesis effects on Posidonia oceanica (L.) Delile phenology in the Bay of Calvi (Corsica, Mediterranean Sea). Hydrobiologia 455, 121-125.
Havelange, S., Lepoint, G., Dauby, P., Bouquegneau, J.-M., 1997. Feeding of the sparid fish Sarpa salpa in a seagrass ecosystem: Diet and carbon flux. P.S.Z.N.I. Mar. Ecol. 18, 289-297.
Hemminga, M.A., Harrison, P.G., Van Lent, F., 1991. The balance of nutrient losses and gains in seagrass meadows. Mar. Ecol. Prog. Ser. 71, 85-96.
Hemminga, M.A., Marbà, N., Stapel, J., 1999. Leaf nutrient resorption, leaf lifespan and the retention of nutrients in seagrass systems. Aquat. Bot. 65, 141-158.
Klap, V.A., Hemminga, M.A., Boon, J.J., 2000. Retention of lignin in seagrasses: Angiosperm that return to the sea. Mar. Ecol. Prog. Ser. 194, 1-11.
Kraemer, G.P., Mazzella, L., 1999. Nitrogen acquisition, storage and use by the co-occurring Mediterranean seagrasses Cymodocea nodosa and Zostera noltii. Mar. Ecol. Prog. Ser. 183, 95-103.
Lepoint, G., Nyssen, F., Gobert, S., Dauby, P., Bouquegneau, J.-M., 2000. Relative impact of a Posidonia seagrass bed and its adjacent epilithic algal community in consumers diet. Mar. Biol. 136, 513-518.
Lepoint, G., Millet, S., Dauby, P., Gobert, S., Bouquegneau, J.-M.An annual nitrogen budget of the seagrass Posidonia oceanica as determined by in situ uptake experiments. Mar. Ecol. Prog. Ser. 237, 87-96.
Marba, N., Cebrian, J., Enriquez, S., Duarte, C.M., 1996. Growth patterns of western Mediterranean seagrasses: Species-specific responses to seasonal forcing. Mar. Ecol. Prog. Ser. 133, 203-215.
Patriquin, D.G., 1972. The origin of nitrogen and phosphorus for growth of the marine angiosperm Thalassia testudinum. Mar. Biol. 15, 35-46.
Pedersen, M.F., Borum, J., 1992. Nitrogen dynamics of eelgrass Zostera marina during a late summer period of high growth and low nutrient availability. Mar. Ecol. Prog. Ser. 80, 65-73.
Pedersen, M.F., Paling, E.I., Walker, D.I., 1997. Nitrogen uptake and allocation in the seagrass Amphibolis antarctica. Aquat. Bot. 56, 105-117.
Pergent-Martini, C., Rico-Raimondo, V., Pergent, G., 1994. Primary production of Posidonia oceanica in the Mediterranean basin. Mar. Biol. 120, 9-15.
Romero, J., 1989. Primary production of Posidonia oceanica beds in the Medes Islands (Girona, NE Spain). In: Boudouresque, C.-F., Meinesz, A., Fresi, E., Gravez, V. (Eds.), International Workshop on Posidonia Beds 2. GIS Posidonies, Marseilles, pp. 63-67.
Shaver, G.R., Melillo, J.M., 1984. Nutrient budgets of marsh plants: Efficiency concepts and relation to availability. Ecology 65, 1491-1510.
Stapel, J., Hemminga, M.A., 1997. Nutrient resorption from seagrass leaves. Mar. Biol. 128, 197-206.
Stapel, J., Hemminga, M.A., Bogert, C.G., Maas, Y.E.M., 2001. Nitrogen (15N) retention in small Thalassia hemprichii seagrass plots in an offshore meadow in South Sulawesi, Indonesia. Limnol. Oceanogr. 46, 24-37.
Zieman, J.C., 1974. Methods for the study of the growth and production of turtle grass, Thalassia testudinum König. Aquaculture 4, 139-143.
