Seasonal changes in diatom biomass, sediment stability and biogenic stabilization in the Severn Estuary

Epipelic diatoms represented the dominant microphy tobenthos on the intertidal mudflats of the Severn Estuary, south-western Britain. Algal biomass (measured as chlorophyll a concentration) varied over a seasonal cycle and was strongly correlated with sediment shear strength and critical shear stress and therefore with position on the shore. High levels of diatom biomass were positively correlated with the concentration of colloidal carbohydrate within the surface sediments. The critical shear strength for incipient erosion was significantly correlated with position on the shore (moisture content) and with both chlorophyll a and colloidal carbohydrate, the latter being the best biochemical predictor for the incipient erosion threshold. The range of stress required to cause incipient erosion varied from 1.0 to 8.0 N m -2 , with the sediment increasing in resistance landwards. Two-way analysis of variance using both moisture content and colloidal carbohydrate as variables explained the stability of the sediment better than individual pair-wise comparisons.

[1]  J. Pinckney,et al.  Effects of Tidal Stage and Sun Angles on Intertidal Benthic Microalgal Productivity , 1991 .

[2]  G. Cadée,et al.  Primary production of the benthic microflora living on tidal flats in the Dutch Wadden Sea , 1974 .

[3]  R. Aller,et al.  Meiofauna and solute transport in marine muds , 1992 .

[4]  P. Montagna,et al.  The relationship between abundances of meiofauna and their suspected microbial food (diatoms and bacteria) , 1983 .

[5]  C. Amos,et al.  Sea Carousel--A Benthic, Annular Flume , 1992 .

[6]  Gerardo M. E. Perillo,et al.  An ecological cascade effect: Migratory birds affect stability of intertidal sediments , 1993 .

[7]  David M. Paterson,et al.  Short‐term changes in the erodibility of intertidal cohesive sediments related to the migratory behavior of epipelic diatoms , 1989 .

[8]  I. N. McCave,et al.  Seasonal shifts of sediment within an estuary mediated by algal growth , 1979 .

[9]  C. Amos,et al.  The Influence of Subaerial Exposure on the Bulk Properties of Fine-grained Intertidal Sediment from Minas Basin, Bay of Fundy , 1988 .

[10]  P. Montagna.  In situ measurement of meiobenthic grazing rates on sediment bacteria and edaphic diatoms , 1984 .

[11]  C. Little,et al.  Subaerial exposure and changes in the stability of intertidal estuarine sediments , 1990 .

[12]  J. Grant,et al.  The interaction between benthic diatom films and sediment transport , 1986 .

[13]  R. Warwick,et al.  Static and dynamic environmental factors determining the community structure of estuarine macrobenthos in SW Britain: why is the Severn estuary different? , 1991 .

[14]  A. Decho,et al.  Microbial exopolymer secretions in ocean environments: their role(s) in food webs and marine processes , 1990 .

[15]  M. Deflaun,et al.  Relationships between bacteria and grain surfaces in intertidal sediments1 , 1983 .

[16]  K. Sundbäck,et al.  The influence of benthic microalgae on the stability of a subtidal sediment , 1993 .

[17]  Giselher Gust,et al.  Prediction of coastal sediment stability from photopigment content of mats of purple sulphur bacteria , 1987, Nature.

[18]  L. Cammen.  Annual bacterial production in relation to benthic microalgal production and sediment oxygen uptake in an intertidal sandflat and an intertidal mudflat , 1991 .

[19]  F. Colijn,et al.  Species Composition of Benthic Diatoms and Distribution of Chlorophyll a on an Intertidal Flat in the Dutch Wadden Sea , 1981 .

[20]  P. D. Boer,et al.  Mechanical effects of micro-organisms on intertidal bedform migration * , 1981 .

[21]  W. Reichardt,et al.  Impact of Arenicola marina on bacteria in intertidal sediments , 1991 .

[22]  V. N. Jonge,et al.  Primary production of microphytobenthos in the Ems-Dollard Estuary , 1984 .

[23]  L. Cammen,et al.  The relationship between bacteria and micro-algae in the sediment of a Bay of Fundy mudflat , 1986 .

[24]  D. Morrisey.  Differences in effects of grazing by deposit-feeders Hydrobia ulvae (Pennant) (Gastropoda : Prosobranchia) and Corophium arenarium Crawford (Amphipoda) on sediment microalgal populations. I. Qualitative differences , 1988 .

[25]  A. R. Nowell,et al.  Effects of bacterial exopolymer adhesion on the entrainment of sand , 1990 .

[26]  W. Admiraal,et al.  Observations and experiments on the population dynamics of epipelic diatoms from an estuarine mudflat , 1982 .

[27]  B. Jørgensen,et al.  Microalgal photosynthesis and spectral scalar irradiance in coastal marine sediments of Limfjorden, Denmark , 1992 .

[28]  M. Pace,et al.  Weak coupling of bacterial and algal production in a heterotrophic ecosystem: The Hudson River estuary , 1991 .

[29]  P. Wong,et al.  Determination of carbohydrate in lake sediment by a modified phenol-sulfuric acid method , 1973 .

[30]  M. Pace,et al.  Bacterial production in fresh and saltwater ecosystems: a cross-system overview , 1988 .

[31]  G. Underwood,et al.  Recovery of intertidal benthic diatoms after biocide treatment and associated sediment dynamics , 1993, Journal of the Marine Biological Association of the United Kingdom.

[32]  J. Hobbie,et al.  Use of nuclepore filters for counting bacteria by fluorescence microscopy , 1977, Applied and environmental microbiology.

[33]  E. A. Delo,et al.  Estuarine Muds manual , 1988 .

[34]  P. S. Meadows,et al.  Modification of sediment permeability and shear strength by two burrowing invertebrates , 1989 .

[35]  V. N. Jonge,et al.  Fluctuations in the Organic Carbon to Chlorophyll a Ratios for Estuarine Benthic Diatom Populations , 1980 .

[36]  Karsten Reise,et al.  Tidal Flat Ecology , 1985, Ecological Studies.

[37]  F. Smith,et al.  COLORIMETRIC METHOD FOR DETER-MINATION OF SUGAR AND RELATED SUBSTANCE , 1956 .

[38]  K. Reise.  Tidal Flat Ecology: An Experimental Approach to Species Interactions , 1985 .