Aerial and Field SAV Observations

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September SAV update with numbers for lower bay

September 30th, 2009 by Robert Orth · No Comments

September’s weather was a bit more favorable for us to fly but still far from perfect. The winds were better that what we had for several weeks, but the tides were still higher than predicted due to local winds.

We took advantage of the few good days with the right tide, wind and sun angle to fly good portion of the lower and middle bay.  We flew the tidal freshwater regions of the Piankatank, James and Mattaponi rivers on Sept. 6; the Chester River, and main bay shoreline from Eastern Neck Island to the Sassafras River on Sept. 14; the upper Potomac River from Washington to just above Quantico on Sept. 15, and the Honga River/ Tar Bay area, Little Choptank and lower Choptank, and lower Potomac rivers on Sept. 20.  For the Potomac, we have to have an armed police officer to fly with our contractor when they fly over DC.

Here is a brief summary of what we have seen in this photography:

Piankatank River - many of the dense beds we had noted in previous years in the upper reaches are gone.  We had reports that sparse beds of coontail were present in early summer but they appear absent now.

Mattaponi River - the upper reaches around the Whitehall region is loaded in many of the same locations as in previous years.  One field survey this summer found hydrilla dominating those beds as in past years.

James River - we once again saw no SAVs in the mainstem James.  However, almost all the creeks up to Hopewell (e.g. Grays Creek, Upper Chippokes Creek, Wards Creek but especially Powells and Herring creeks) had a fair amount of SAV present.  The Chickahominy, one of the larger rivers entering the mid-James, had abundant SAV.  One field survey in the Chickahominy found N. minor in the lower reaches.  Hydrilla has been dominating the upper reaches.

Chester River area - the Chester is essentially devoid of SAV except what is present in Robins Pond.  Around Eastern Neck Island there are small pockets of SAV but only in Hail Creek and Tubby and Half Pasture coves.  Terry Willis has provided a good deal of ground data for this region which is posted on our blog (http://thumper-web.vims.edu/bio/sav/wordpress/).  Along the mainstem, the only significant beds appeared to be around the Rock Hall Harbor area.

Upper Potomac River - the mainstem regions from just above Quantico to the WW Bridge look very robust.  SAV in many of the creeks look great.  SAV around the bridge (the ‘big’ bed) is sparse.  There is little SAV above the bridge with most found along the Roosevelt Island area.  We are going to refly some of this area as SAV in a few areas that appeared really thick last year don’t appear as dense or widely distributed this year (e.g. Piscataway Creek) and the sparse beds may have been compromised by some unusual turbidity in only these creeks.

Lower Potomac River - the only SAV beds we saw were in the St. Mary’s River and even here they were noticeably reduced from 2008.  Widgeongrass in the St. Georges Creek area are gone and the only beds we saw were the SAV beds that were composed of eelgrass that the MD-DNR people planted.  The big widgeongrass beds in Breton and St. Clements bays and down along that mainstem side from those bays are absent this year.  There were no SAV beds along the Virginia side.

Honga River and Tar Bay - the SAV beds look great!  Widgeongrass dominated this region and it appears the beds here are doing quite well this year. Little Choptank River almost no SAV was observed here.  However, in the Brannock and Trippe bays, just above the Little Choptank, there were some sizeable beds but appear to be reduced from 2008.

Lower Choptank River - along the South Shore some smaller beds were noted in the area of Cooks Point Cove and Chapel Creek but nothing like in previous years.  Along the north shore some sizeable beds (dominated by widgeongrass) were present in Irish Creek and in a number of different locations in the small creeks and coves off Broad Creek.  Total SAV coverage for the river will probably be down for 2008.

On another note, we have now completed the initial SAV interpretation for the lower western shore areas up to the mouth of the Potomac River and the eastern shore up to Bloodsworth Island.  Our earlier comments regarding increased coverage of SAV fueled by the continuing recovery of eelgrass from the 2005 dieback and expansion of widgeongrass in some areas are now borne out by the numbers.  Initial, unchecked numbers for the western shore beds show they have increased about 912 ha to 5,903 ha from 5,025 ha in 2008, while the eastern shore SAV beds have increased 1,630 ha to 9,535 ha from 8,041 ha in 2008.  The overall coverage represents about 50% of the total SAV in the bay.

Please check our web site (http://www.vims.edu/bio/sav) if you are interested in SAV in particular areas for 2009 or want to read some of the SAV observations reported by our colleagues (http://thumper-web.vims.edu/bio/sav/wordpress) or look at the 2008 SAV distribution on our GOOGLE interactive map (http://web.vims.edu/bio/sav/maps.html?svr=www).

Tags: Aerial Updates · SAV Observations

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