Aerial and Field SAV Observations

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August update on SAV observations

September 1st, 2009 by Robert Orth · No Comments

The SAV aerial survey has had a bad bout of the summer doldrums due to some really lousy weather as well as uncooperative tide conditions.  Once the tides started getting back to normal in mid-July, the weather became especially troublesome with a lot of hot and hazy atmospheric conditions.  And to top this off August down here in the lower bay was the third wettest month on record!   In addition, we had some really challenging low tides that were more astronomical this time versus the meteorological driven ones back in June.  For parts of August we had unequal low tides, with the morning lows almost a foot higher than both mean low and the afternoon low tide. Since we usually fly in the morning when it is less cloudy, we had to abort several planned missions in the mid-bay as an extra foot of water would mean we would not see the deep edges. However, we did manage to fly the Patuxent, Susquehanna, and Elk rivers and the Flats.  Below are our observations for those areas.  Also, I have included a brief synopsis of what we have heard from other colleagues looking at SAVs this summer.

In general, SAV in the Patuxent is similar to previous years.  It appears widgeongrass has re-appeared in the lower River along the north shore up from Drum Point at the mouth.  That bed is like many widgeongrass beds here one day, gone the next. There are some beds along the upriver side of Broomes Island which have always been dominated by widgeongrass.  It’s not until we get up to Cocktown and Black Swamp creeks near Kings Landing Park that we see freshwater SAV. Tom Harten, who monitors SAV in Cocktown Creek with his high school students, noted an unusual increase in Vallisneria this year in addition to the usual abundance of hydrilla. From this point all the smaller creeks entering the river appear to contain very narrow strips of SAV in the photos. This is similar to what we noted before even when SAV did not occupy the mainstem.  Along the mainstem SAV appears on the many shoals from Fridays Creek in abundances similar to last year.  So SAV in this section of the Patuxent appears to be having another good year.

We were only able to fly 4 of the 7 lines over the Flats but they show the massive bed on the Flats once again this year.  It appears in MODIS when it is not obscured by clouds which was quite frequent this summer
(http://rapidfire.sci.gsfc.nasa.gov/subsets/index.php?subset=AERONET_Wallops). It now pretty much covers the entire region except for the channels.  The flanks of the Flats from Havre de Grace along the eastern margin and south from the Northeast River along the western margin are also thick with SAV.  The Elk River also appears loaded with SAV.  I am not sure there is room for any more!  It is indeed another impressive year in this region of the bay!

While the aerial flights have been limited we have received observations on our blog from people who have visited regions of the Bay, suggesting SAV may be struggling in some areas but doing well in others.  Peter Bergstom reported low abundances of SAV in the Magothy and Severn rivers, as well as Marshy Creek in the Eastern Bay area compared to past years including the lack of flowering in widgeongrass, something we have noted at quite a few locations in the lower bay.  SAV in the Chester, including around Eastern Neck Island, appears dismal according to Terry Willis.  VA DEQ staff report some places in the upper Potomac River are unexpectedly loaded with SAV.  SAV in several of the VA tribs (Mattaponi, Chickahominy) appear to be robust.  Chris Tanner reports that widgeongrass in the St Mary’s may be down this year.  Lee Karrh commented that they have had reports (actually, complaints) of a lot of milfoil in the Baltimore area.  Widgeongrass showed up around Poplar Islands this year according to Chris Guy who shared with us some pretty neat pictures of SAV in this area under some amazing water clarity.

We have not gotten much info for the MD coastal bays except that water clarity has been pretty lousy this year.  A lot of ground observations have been made, but I am still awaiting that information.  Eelgrass in our restoration areas in the VA coastal bays appeared very robust a few weeks ago when we were there
conducting our first bay scallop deployment.

If any of you have anything to add to these observations please add them to our blog or just send them to me and my staff will add them.

September awoke to some really nice, cool weather!  At last!  And let’s hope hurricanes do what Bill and Danny did - stay away!

Tags: Aerial Updates · SAV Observations · Water Quality

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