179 



creeks can be defined as the ratio of length of edge of tidal creeks to 

 surface area of marsh. Knowledge of the influence of creek density on 

 habitat utilization and material exchange may be essential to understanding 

 the relative value of marshes that develop in response to sea level rise. 

 Comparative studies of the effects of creek density have never been 

 reported, however. 



Finally, valuable predictions of coastal changes may be obtained from 

 empirical models, if sufficient data can be collected. Four areas of study 

 will contribute. First, paleoecological analysis of cores from various 

 coastal ecosystems can assess responses to past sea level rise (Kurz and 

 Wagner, 1957). Second, analysis of ecological zonation along gradients of 

 salinity and elevation should reflect the kinds of ecosystems to be 

 expected as salinity encroaches and water becomes deeper. Third, analysis 

 of the effects of "experiments of opportunity", in which human or natural 

 events have altered local sea level or caused salinity intrusions, may 

 simulate future effects of sea level rise." Lastly, greater knowledge of 

 the environmental variation under which each major type of system can now 

 exist is needed. Detailed physiometric studies of coastal ecosystems are 

 limited to a few areas, usually near marine research laboratories. Results 

 are often extrapolated to other sites. A given set of predicted 

 environmental conditions, however, may not match those of these few study 

 sites. Each type of coastal system may exist in a much broader range of 

 environments than is now documented, and gradual changes probably occur 

 between system types. Greater regional knowledge of the variety of 

 ecosystem types, and of the variety of environments that support the same 

 ecosystem, will enhance the resolution of empirical ecological predictions. 



^T.J. Smith and W.M. Kitchens, comments on Chapter 11, see appendix. 



