I grew up along the banks of the Rappahannock River, one of the many tributaries of the Chesapeake Bay here in Virginia. I was aware very early on that the livelihoods and lifestyles of the people in this rural area were closely tied to the health of the river and bay and the harvest of blue crabs and oysters they yielded. The problems in the Chesapeake Bay and its tributaries run the gamut from waterfront development, increases in run-off sediment, disease in the oyster population, the decline of the blue crab population, and "dead spots" where the oxygen level of the water is too low to support marine life. Steps to correct the situation resulted in the passage of the Chesapeake Bay Preservation Act (Bay Act) by Virginia in 1988. So far, the results have not been good.
I would track the oyster population over time as the key way to illustrate the decline of the Bay's health; history has shown that these two factors have continued to coincide. Hard elements within the Bay ecosystem include the amount of marsh that acts as a filter for run off, the oyster population that acts as a filter feeder, and the oxygen stats of various bodies of water throughout the watershed. The soft elements in the Bay system include the deeply proud "waterman's culture" that promotes continued fishing even when it is not economically viable, the poaching of various marine life, and local farmer's resistance to abide by the terms of the Bay Act.
Nice post, Ken. This is indeed a good example of a problem that could benefit from a system dynamics analysis. I also like your choice of "hard variables" (oyster pop). This doesn't tell the whole story, but it serves as a good surrogate for the overall health of the bay.
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