A mathematical model for the vertical distribution of chlorophyllA in estuarine intertidal sediments
Tóm tắt
Coastal and estuarine intertidal sediments are commonly colonized by dense populations of microphytobenthos. Due to wind and tides, important fractions of microphytobenthic populations may be buried. A mathematical model describing the depth variation of chlorophyll a in intertidal sediments was developed and experimentally tested. The model assumed first-order chlorophylla degradation and a constant mean burial velocity which resulted in a negative exponential variationC
Z
=C
O
exp{-k/vz} (C
Z
andC
O
=chlorophylla concentration at depth zand at the surface;k=specific degradation rate of chlorophyll a to pheopigments;V=mean burial velocity). Chlorophylla concentration depth profiles in different sediment types measured at the Tagus estuary and Ria Formosa (Portugal) were used to validate the model. The model was adjusted to field data. The chlorophyll a degradation rate was measured in a microcosm experiment under total darkness and no tidal action, and sampled during three months. This rate was shown to be independent of time and depth for the upper 0–15 mm depth interval. This result allowed the estimation ofV for each sampling site. Comparison of predicted and observed temporal data further confirmed the validity of the model andk andV values. Despite its simplicity, the proposed model adequately described the depth distribution of chlorophylla in different types of intertidal sediments. The model allowed the quantitative characterization of the buried microphytobenthic biomass (depth-integrated biomass) and the assessment of its importance as potentially productive stock of cells.
Tài liệu tham khảo
ABELE-OESCHGER, D. 1991. Potential of some carotenoids in two recent sediments of Kiel Bight as biogenic indicators of phytodetritus. Mar. Ecol. Prog. Ser., 70: 83–92.
ADMIRAAL, W., 1984. The ecology of estuarine sediment-inhabiting diatoms. Prog. Phycol. Res., 3: 269–323.
ADMIRAAL, W., VAN ARKEL, M. A., BARETTA, J. W., COLIJN, F., EBENHÖH, W., DE JONGE, V. N., KOP, A. RUARDIJ, P. and SCHRÖDER, H. G. J., 1988. The construction of the benthic submodel. In: J. Baretta and P. Ruardij, Eds;, Tidal flat estuaries. Simulation and analysis of the Ems estuary. Springer-Verlag, Berlin: 105–152.
ANDERSEN, F. O. and E. KRISTENSEN, 1992. The importance of benthic macrofauna in decomposition of microalgae in a coastal marine sediment. Limnol. Oceanogr., 37: 1392–1403.
BIANCHI, T. S. and S. FINDLAY, 1991. Decomposition of Hudson Estuary Macrophytes: Photosynthetic Pigment Transformations and decay constants. Estuaries, 14(1): 65–73.
BLANCHARD, G. F. and P. MONTAGNA, 1992. Photosynthetic response of natural assemblages of marine benthic microalgae to short- and long-term variations of incident irradiance in Baffin Bay, Texas. J. Phycol., 28: 7–14.
BROTAS, V., A. AMORIM-FERREIRA, C. VALE and F. CATARINO, 1990. Oxygen profiles in intertidal sediments of Ria Formosa (S. Portugal). Hydrobiologia, 207: 123–129.
BROTAS, V., T. CABRITA, A. PORTUGAL, J. SERÔDIO and F. CATARINO, 1995. Spatio-temporal distribution of microphytobenthic biomass in tidal flats of the Tagus estuary (Portugal). Hydrobiologia, 300/301: 93–104.
CADÉE, G. C. and J. HEGEMAN, 1974. Primary production of the benthic microflora living on tidal flats in the Dutch Wadden Sea. Neth. J. Sea Res., 8: 260–291.
COLIJN, F. and V. N. DE JONGE, 1984. Primary production of the microphytobenthos in the Ems-Dollard estuary. Mar. Ecol. Prog. Ser., 14: 185–196.
DAEHNICK, A. E., M. J. SULLIVAN and C. A. MONCREIFF, 1992. Primary production of the sand microflora in seagrass beds of Mississippi Sound. Bot. Mar., 35: 131–139.
DAVIS, M. W. and C. D. McINTIRE, 1983. Effects of physical gradients on the dynamics of sediment-associated algae. Mar. Ecol. Prog. Ser., 13: 103–114.
DE JONGE, V. N. and J. E. E. VAN BEUSEKOM, 1992. Contribution of resuspended microphytobenthos to total phytoplankton in the Ems estuary and its possible role for grazers. Neth. J. Sea. Res., 30: 91–105.
DE JONGE, V. N. and F. COLIJN, 1994. Dynamics of microphytobenthos biomass in the Ems estuary. Mar. Ecol. Prog Ser., 104: 185–196.
DELGADO, M., V. N. DE JONGE and H. PELETIER, 1991. Experiments on resuspension of natural microphytobenthos populations. Mar. Biol., 108: 321–328.
FIELDING, P. J., K. St. J. DAMSTRA and G. M. BRANCH, 1988. Benthic diatom biomass, production and sediment chlorophyll in Langebaan Lagoon, South Africa. Estuar. Coast. Shelf Sci., 27: 413–426.
LEAVITT, P. R. and S. R. CARPENTER, 1990. Aphotic pigment degradation in the hypolimnion: Implications for sedimentation studies and paleolimnology. Limnol. Oceanogr., 35: 520–534.
LORENZEN, C. J., 1967. Determination of chlorophyll and pheo-pigments: spectrophotometric equations. Limnol. Oceanogr., 12: 343–346.
MAHAUT, M. L. and G. GRAF, 1987. A luminophore tracer technique for bioturbation studies. Oceanol. Acta, 10: 323–328.
NIENHUIS, P. H. and B. H. H. DE BREE, 1984. Carbon fixation and chorophyll in bottom sediments of brackish Lake Grevelingen, The Netherlands. Neth. J. Sea Res., 18: 337–359.
OFFICER, C. B. and D. R. LYNCH, 1989. Bioturbation, sedimentation and sediment-water exchanges. Estuar. Coast. Shelf Sci., 28: 1–12.
PLANTE-CUNY, M. R., 1977. Répartition à la surface et au sein du sédiment de la chlorophylle a et des phéopigments de quelques substrats meubles tropicaux immergés. J. Rech. Oceanogr. 2: 1–11.
RIAUX, C., 1982. La chlorophyllea dans un sédiment estuarien de Bretagne Nord. Ann. Inst, océanogr. Paris, 58: 185–203.
SANFORD, L. P., 1992. New sedimentation, resuspension, and burial. Limnol. Oceanogr., 37: 1164–1178.
SOKAL, R. R. and F. J. ROHLF, 1981. Biometry, 2nd ed. W. H. Freeman and Company, New York.
STOCKNER, J. G. and J. W. G. LUND, 1970. Live algae in postglacial lake deposits. Limnol. Oceanogr., 15: 41–58.
VARELA, M. and E. PENAS, 1985. Primary production of benthic microalgae in an intertidal sand flat of the Ria de Arosa, NW Spain. Mar. Ecol. Prog. Ser., 25: 111–119.
WHEATCROFT, R. A., 1992. Experimental tests for particle size-dependent bioturbation in the deep ocean. Limnol. Oceanogr., 37: 90–104.