Microphytobenthos in Contrasting Coastal Ecosystems: Biology and Dynamics
121
5.8 Conclusions
Hydrodynamic forces regulate the distribution of sediments within coastal
depositional ecosystems and hence the structure and function of microphytobenthic assemblages. At the extremes, non-cohesive sediments are typically
associated with high-energy environments, and microphytobenthos is sparse
and dominated by microbes that attach directly to individual grains. In
contrast, motile microbes dominate the cohesive sediments of low-disturbance environments. However, microphytobenthos are not passive inhabitants
and can directly affect sediment stability through the production and
secretion of organic polymers, known as extracellular polymeric substances
(EPS), and network formation (cE. cyanobacteria). The biostabilisation of
sediments thus serves as a feedback mechanism regulating sediment erosion
and sediment characteristics. The degree of biostabilisation also differs dramatically between non-cohesive and cohesive sediments. In this chapter we
have outlined some of the physical and biological differences between noncohesive and cohesive sediments. The physical differences include the hydrodynamic processes that control sediment distribution and erosion. The biological differences include adaptation by the microphytobenthos, diversity,
and the complex factors that regulate sediment biostabilisation and assemblage structure.
Acknowledgements. This review was supported by contributions from the EU through
the BIOPTIS (MAS3-CT97-0158) and CLIMEROD (MAS3-CT98-0166) programmes
and from work and discussions with Dr. T. Tolhurst, Heather Austin (University of
st. Andrews), Emma Defew, Catherine Biles (NERC GR3112370) and Mireille Consalvey
(NERC GR3111782). ED, CB and MC also supplied negatives for Fig. 5.1. Irvine Davidson
completed the SEM studies. This help is gratefully acknowledged.
References
Admiraal W (1984) The ecology of estuarine sediment-inhabiting diatoms. In: Round
FE, Chapman DJ (eds) Progress in phycological research, vol 3. Biopress, Bristol, UK
pp 269-322
Allen JRL (1984) Sedimentary structures: their character and physical basis. Elsevier,
Oxford
Amos CL, Feeney T, Sutherland TF, Luternauer JL (1997) The stability and erodibility of
fine-grained sediments from the Fraser River delta foreshore and upper foreslope. Est
Coastal Shelf Sci 45:507-524
Bergey E (1999) Crevices as refugia for stream diatoms: effect of crevice size on abraded
substrates. Limnol Oceanogr 44:1522-1529
121
5.8 Conclusions
Hydrodynamic forces regulate the distribution of sediments within coastal
depositional ecosystems and hence the structure and function of microphytobenthic assemblages. At the extremes, non-cohesive sediments are typically
associated with high-energy environments, and microphytobenthos is sparse
and dominated by microbes that attach directly to individual grains. In
contrast, motile microbes dominate the cohesive sediments of low-disturbance environments. However, microphytobenthos are not passive inhabitants
and can directly affect sediment stability through the production and
secretion of organic polymers, known as extracellular polymeric substances
(EPS), and network formation (cE. cyanobacteria). The biostabilisation of
sediments thus serves as a feedback mechanism regulating sediment erosion
and sediment characteristics. The degree of biostabilisation also differs dramatically between non-cohesive and cohesive sediments. In this chapter we
have outlined some of the physical and biological differences between noncohesive and cohesive sediments. The physical differences include the hydrodynamic processes that control sediment distribution and erosion. The biological differences include adaptation by the microphytobenthos, diversity,
and the complex factors that regulate sediment biostabilisation and assemblage structure.
Acknowledgements. This review was supported by contributions from the EU through
the BIOPTIS (MAS3-CT97-0158) and CLIMEROD (MAS3-CT98-0166) programmes
and from work and discussions with Dr. T. Tolhurst, Heather Austin (University of
st. Andrews), Emma Defew, Catherine Biles (NERC GR3112370) and Mireille Consalvey
(NERC GR3111782). ED, CB and MC also supplied negatives for Fig. 5.1. Irvine Davidson
completed the SEM studies. This help is gratefully acknowledged.
References
Admiraal W (1984) The ecology of estuarine sediment-inhabiting diatoms. In: Round
FE, Chapman DJ (eds) Progress in phycological research, vol 3. Biopress, Bristol, UK
pp 269-322
Allen JRL (1984) Sedimentary structures: their character and physical basis. Elsevier,
Oxford
Amos CL, Feeney T, Sutherland TF, Luternauer JL (1997) The stability and erodibility of
fine-grained sediments from the Fraser River delta foreshore and upper foreslope. Est
Coastal Shelf Sci 45:507-524
Bergey E (1999) Crevices as refugia for stream diatoms: effect of crevice size on abraded
substrates. Limnol Oceanogr 44:1522-1529