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Analysis of Plant Samples from 'Dead Marsh' Sites - A Pilot Study
PI: Chandra Franklin (Savannah State University, Savannah, GA, USA)
Support: Sea Grant College Program
Timeframe: 2003 - 2004
Progress and Findings:
root mass. A key observation from the morphological analyses
was that underground plant parts from dead marsh sites (where aboveground vegetation
is destroyed) were dead as well. It is entirely possible that in some affected
regions, there may be living underground material, and re-growth may occur in
Herbivory. The frequency of damage to aerial parts of plants caused by insect larvae was noticeably high. Of the 60 samples examined with intact aerial parts (i.e., those from healthy and transition zones), 29 showed a similar type of insect damage. Damage to vegetation caused by insect larvae is not uncommon in a natural setting (i.e. without the application of insecticide or other preventive measures), and under normal circumstances it may not lead to the destruction of an entire salt marsh. However, the frequency of insect damage observed in samples analyzed thus far appears to be unusually high indicating that insects may contribute to the loss of vegetation in salt marshes. This can only be confirmed by examining a large number of samples.
Damage at the cellular level. Analysis of plant samples at the cellular level revealed an unusual difference between samples from living and dead marshes. Xylem vessels in the rhizomes of samples from dead marshes (and in some cases transition zones as well) were clogged with a yellowish-brown colored substance. A xylem vessel is a type of cell in the vascular system of higher plants and is responsible for the transportation of water throughout the plant. In some plants, the clogging of xylem vessels may result from pathogen attack or from the presence of toxic substances. Whether the clogging of xylem vessels of S. alterniflora from dead or dying marshes is associated with a pathogen attack, or toxic substances (e.g. herbicides) is yet to be determined.
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|This page was updated October 13, 2006|