Friday, September 07, 2007

Water Quality in Long Island Sound is Better than Average this Summer

The low-oxygen conditions that hit the western half of Long Island Sound every summer are not as bad in 2007 as they have been in recent years. The Connecticut DEP’s water quality survey results came out yesterday and the area with dissolved oxygen concentrations below 3.5 milligrams per liter (that is, the point at which things start getting bad) is relatively small – just 67.9 square kilometers (26.2 square miles):

The areal extent is well below the long term average and the lowest since 2002.

Most of the DEP’s 2007 hypoxia maps are now online, here.

Coincidentally, I
wrote yesterday about a question from Sally Harold of The Nature Conservancy, who asked me what I knew about an apparent paucity of jellyfish in the Sound this summer. I had no clue, but the Connecticut DEP noticed the same thing that Sally did. In her water quality report, Katie O’Brien-Clayton wrote:

We have also not encountered many ctenophores in the plankton tows this summer.

Ctenophores are comb jellies.

So I guess it's true. For whatever reason, there are fewer ctenophores around this summer. I'd still like to hear some ideas about why that is so.



Blogger Sam said...

Not sure, Tom. The folks saw the same effect down in the Chesapeake and hypothesized that is could be a salinity issue - as in the lack of salinity. I do seem to recall massive blooms of comb jellies some years, and then seeing few or none in other years. Apparently, they can live in very deep waters as well.

2:49 PM  

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