|Effects of sea-level anomalies on estuarine processes|
Morris, J.T. (2000). Effects of sea-level anomalies on estuarine processes, in: Hobbie, J.E. (Ed.) Estuarine science: a synthetic approach to research and practice. pp. 107-127
In: Hobbie, J.E. (Ed.) (2000). Estuarine science: a synthetic approach to research and practice. Island Press: Washington D.C. ISBN 1-55963-700-5. XI, 539 pp., more
Several of the effects of sea-level anomalies on estuarine processes including primary production and nutrient cycling are illustrated using data collected at North Inlet, South Carolina. Interannual and seasonal variations in sea level affect material exchanges between the intertidal zone and waters. Mean annual sea level varies from year to year along the southeast coast by an average of ±2.9 cm, which is nearly an order of magnitude greater than the annual change in long-term sea-level rise. Mean monthly sea level varies periodically over the solar annual cycle with an average of 24 cm, though both the range and months of maximum water level vary year to year. These anomalous tidal components change the frequency of flooding of intertidal salt marshes, the area of marsh flooded at high and hydraulic gradients. One effect of these anomalies is a change in the salt balance of intertidal sediments. When sea level is anomalously low, salt-marsh primary production decreases because of an increase in pore-water salinity. The net aboveground production of the salt-marsh grass Spartina alterniflora varies yearly by a factor of 2 and is negatively correlated with summer pore-water salinity. Sea-level anomalies may also modify exchanges of nutrients and sediments between the vegetated intertidal zone and open water. The vegetated intertidal areas of North Inlet appear to be net resources of nutrients to the tidal creeks and can account for a large fraction of the net export of nutrients from North Inlet to adjacent coastal waters. Changes in hydraulic gradients and extent of area flooded brought on by variation in mean sea level should be ecologically significant and affect the nutrient budgets of estuaries.