Tuesday, January 25, 2011

Lucky Weather Gave the Bay a Break in 2010

Most summer conditions better than average:

  • Below average fish kills
  • Less abundant sea nettles
  • Smaller volume of low dissolved oxygen
  • Above average winter flow, below average late spring and summer flow into the Bay
  • Above average air temperatures
  • Average to above average frequency of westerly winds in early summer and southeasterly winds in late summer
Summer conditions for 2010 were influenced by above average winter flow and below average late spring and summer flow into the Bay. The timing of flow was important this year, in comparison to 2009, when the spatial pattern of flow into the Bay was important. Additionally, summer air temperatures in 2010 were above average, and combined with flow, can affect phytoplankton and fish in the Bay.

Overall, the Chesapeake Bay experienced relatively minor (total number of dead fish was small) fish kills in 2010. Seven fish kills were associated with low dissolved oxygen alone, three kills were associated with low dissolved oxygen due to algal blooms, and one kill was associated with a harmful algal bloom (HAB) that produced fish-killing toxins. The largest fish kill occurred in the Severn River and was approximately 30,000 fish. The algal blooms species were Karlodinium veneificum (HAB), Gyrodinium uncatenum, and Prorocentrum minimum.

In spring 2010 scientists forecasted below average anoxia (dissolved oxygen <0.2 mg l-1) and hypoxia (DO <2.0 mg l-1) would occur in the mainstem during the summer. For a comparison of summer conditions to the forecasts made this past spring visit the Forecast Accuracy page.
 They say it's better to be lucky, than to be good, but in this case I would prefer good...

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