Aerial and Field SAV Observations

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2009-09-16 Shallow Creek, Patapsco River

September 18th, 2009 by Peter Bergstrom · 1 Comment

I made my annual visit to Shallow Creek on Wed. 9/16 to check the survival of the small scale SAV planting that I supervised there in 1999, 2000, and 2001, with an additional planting supervised by DNR staff in 2003.  Shallow Creek is near North Point on the northern edge of the Patapsco River, technically just outside the river mouth in mainstem segment CB3MH, on quad 19 in the VIMS survey (see 2008 SAV map).  We planted wild celery (Va), redhead grass (Ppf), and sago pondweed (Ppc), but only the first two species survived.  We found no redhead grass in the creek before we started planting it there.  For reports from visits in past years, see: my report from 8-26-08, which has links to all of the earlier reports in the 2nd paragraph.

I went with with Jennifer Greiner, US FWS, who helped with the planting in 2000, and Steve Giordano, another fishery biologist at the NOAA Chesapeake Bay Office.  We found more SAV than I have ever seen there.  The whole upper creek and the upper ends of several coves appeared to be solid milfoil, most of it in flower (see photo), and often from shore to channel (see photo).  However, in the lower creek there were extensive mixtures of milfoil with the 2 species we planted that survived (wild celery and redhead, with more redhead visible than in recent years) plus quite a bit of Elodea (Ec), more than I’ve ever seen there before (see photo).  We did not find any sago pondweed on this visit, however.  See overview map of our whole route showing species found; the points where we turned around were usually where the SAV became too dense to paddle easily.  We were hunting just before low tide, starting about 2 hours before and finishing at low tide.

The main planted area next to the main channel, which I called “Area 1″ in my report last year, seemed at least as large and dense as last year, with much more redhead visible (see photo of bed and close-up).  As we saw in past years in Area 1, there was more redhead in the shallows and more wild celery and some milfoil in deeper water, with the bed in Area 1 extending almost to the channel as it did last year.  The shallower plants were much cleaner, presumably because the deeper ones, closer the the channel, were trapping the sediments before they reached the shallows.   See close-up map of Area 1.

There was some wild celery already present on the north side of the “outer cove” in 1999 when we started planting, and the grasses in that area on 9/16 were short enough, and the water clear enough, that I could shoot some underwater video there, online in YouTube here (32 sec).  The wild celery in this area was genetically distinct from that growing in Area 1, so presumably these plants are descended from the ones we found before we did any planting.  The small area we planted  with Va, Ppf and Ppc in the outer cove, Area 2 on the south side of the cove, still had redhead grass (Ppf) mixed with the other species, and redhead is spreading throughout that cove as well as up the creek.  The cove across from the outer cove, labeled Area 3 on the map (where we did no planting), seemed to have a lot more redhead grass than it did last year.  Last year, those 3 areas (1-3) were the only ones in the creek with dense SAV, but this year there were dense beds in several other coves, and a large milfoil bed that appeared to extend from where we turned around to return to the launch point (waypoint 673 on the overview map) to the upper end of the creek.

Two mute swans and a large flock of Canada geese were chowing down on the grasses.  Salinity was fairly high (9-10 ppt, vs. 8 ppt last year).  Secchi depths were better than last year (0.6-0.8 m, vs. 0.3 m last year).  See graph of Secchi depth and salinity by year (usually one visit per year)–this was the best Secchi depth I’d seen there since 2000, but nowhere near the extreme salinity, which was 15 ppt in Sept. 2002 after 2 years of drought, and 2 ppt the next year after a wet year.  It’s amazing that all of the SAV species in this creek have survived salinity swings from 2 to 15 ppt, and such low Secchi depths.   I hope to collect more water quality data here next year, to try to understand better what’s going on.  The CBIBS buoy outside the Patapsco has been back online since 9/14/09 after being shot and then hit by a ship (see the CBIBS web site and click on its icon for data).  Assuming it stays online, we’ll have some more continuous water quality data from outside Shallow Creek.

Tags: SAV Observations

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