Thursday, March 29, 2012

Bay Grasses Nose Dived in 2011

The results of the annual survey of submerged aquatic vegetation in Chesapeake is out, and the results weren't good
Fewer acres of bay grasses grew in the shallows of the Chesapeake Bay and its tidal rivers in 2011, according to scientists with the Chesapeake Bay Program. Bay grass acreage fell to an estimated 63,074 acres in 2011, down from 79,664 acres in 2010. This is the lowest Bay-wide acreage measured since 2006.
So much for the facts.  Now comes the finger pointing...
  • Summer 2010 was unusually hot, causing severe eelgrass die offs in the lower Bay. These beds had already been measured for the 2010 acreage survey, so these eelgrass losses were not officially recorded until 2011.
  • In spring 2011, heavy rains and resulting runoff created very muddy conditions in the upper Bay and its rivers during the bay grass growing season.
  • Last September, Hurricane Irene and Tropical Storm Lee brought even more rain and mud to the Bay’s waters.
It's no shock to me that the spring floods and September storms played havoc with the grasses in the upper bay.  I would have been surprised if they hadn't, I wonder if the effects due to Irene and Lee have been accounted for, though, as they occurred after the peak growth of the grasses, and presumably after the survey was conducted.  However, it turns out they may also have had a positive effect:
"2011 was the year that bucked two trends we’ve seen over the last decade,” said Lee Karrh, chair of the Bay Program’s Submerged Aquatic Vegetation (SAV) Workgroup. “The Upper Bay had major decreases after years of increasing or sustained high acreages. On the other hand, the brackish parts of the Middle Bay witnessed dramatic increases in 2011, after prolonged decreases since the turn of the century.”
According to the Washington Post, the increase in the Middle Bay was due to lower than normal salinity stimulating the germination of dormant seeds of species more common in the Upper Bay.  Part of the Bay's mysterious restorative processes.  Even the bad things sow the seeds of the good things...

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