Aerial and Field SAV Observations

Aerial and Field SAV Observations header image 2

Shallow Creek, Patapsco River, 8-26-08

August 29th, 2008 by Peter Bergstrom · No Comments

Peter Bergstrom, NOAA Chesapeake Bay Office  (Quad 19)

I visited Shallow Creek by kayak with Mike Lloyd, a student of Maile Neel’s at UMD.  I timed our visit to arrive just before low tide but the SAV in 3 parts of the creek was so dense and long (most Va shoots were lying on the surface) that it would be better to visit at mid or high tide–it was quite hard to paddle through these beds at low tide.  The Secchi depth in the channel was poor, 0.3 m, and the salinity was higher than it has been here in many past years, 8 ppt, with a few sea nettles seen.  We saw fewer mute swans than we saw here a few years ago but we did see one pair of adults with several cygnets, feeding on SAV.  We also saw a number of herons (great blue and green) and a few terns (Forsters and least).

This map with our results shows these 3 very dense areas, all near the mouth of the creek, but scattered clumps of SAV were found almost everywhere we looked in the shallows.  This was more and denser SAV than I have seen in this creek since I started visiting it in 1996.  I have visited Shallow Creek for SAV surveys every year since 1996, except for 1997.  For my reports from Shallow Creek in previous years see: 1998 (1st), 1998 (2nd, found Va), 1999, 2000, 2001, 2004, 2005, 2006, and 2007.  There was a report by others in 1999 of Rm (widgeongrass) there which I have never found; it may have been Ppc (sago pondweed) which I have found in the same area (#2) several times, including in 1999, never with flowers or seeds.

For some photos of what we saw, see Va flowers & pollen, Va at the surface in Area 1 (with Mike and without), me with Va & Ppf in the planted bed (area 1), and a rare (for Shallow Creek) underwater shot of Va (the water was flowing out of Area 2 which was packed with SAV so it was pretty clear).

The shift in SAV species we found there over the years is an interesting story, involving responses to salinity changes, SAV planting (in 1999-2001 and 2003), and natural spread.  In that first year of surveys (1996) we found mostly milfoil (Ms) with some  elodea (Ec).  On our 1998 visit we also found Chara (C) and horned pondweed (Zp).  We did not have time to visit the “Outer Cove” (Area 2 on the attached map) in 1996 but when I started visiting it in 1998, we discovered some small beds of wild celery (Va) in that cove.  Thus, when the Corps asked me to organize a small scale SAV planting in Shallow Creek in 1999, I decided to use one species that grew in the creek (Va) along with two that we had not found there (redhead grass, Ppf and sago pondweed, Ppc).  The 1999 planting was very small and unfenced and did not survive well (we saw over a dozen mute swans in 2000), so we returned in 2000 to plant more of the same species with fencing, concentrating them (three rectangles of plants) in Area 1 (marked on the map) which had never had any SAV except a few shoots of Ms, with a single rectangle in Area 2, across the cove from the natural Va beds.  In 2000, Ppf had the best survival, followed by Va, with little if any survival of Ppc.  Thus in fall 2001 we planted only Ppf in Area 1 when we returned for one more planting, but after the salinity fell in 2003-2004, Va seemed to be doing better than Ppf.  DNR returned in 2003 to do a small Va & Ppf planting in Area 1 next to our 2000 plants.  In Area 1 in 2004 & 2005 the surviving beds of Va & Ppf were still clumped in the rectangles where we planted them, but by 2006 the separate beds had merged, and they remained that way through this year as they became denser and spread in both directions, both towards shore (almost reaching the marsh grass this year!) and almost to the channel on the deep end.  I’m not sure if what we planted in Area 2 in 2000 contributed to the dense beds of Va & Ppf that are there now; the Ppc we found there was not from what we planted.

This spread of Ppf & Va in Area 1 is very satisfying, since I’m pretty sure the plants there came from what we planted in 2000-2003.  However, I keep wondering why this planting was so much more successful than any other small scale planting I’ve supervised, especially given the low Secchi depths and swans we often see there.  The other planting sites I’ve supervised (also Ppf and Va)  have had a maxium survival of 3 years for Ppf at 2 sites with little or no spread beyond the planted area, while the 0.01 ha we planted in Shallow Creek at Area 1 has expanded to about 0.8 ha in 2006 and about 1.5 ha in 2007, and probably more in 2008.

If you are intersted in seeing the beds in Shallow Creek this year, please email me at peter.bergstrom@noaa.gov.  The owner of the ramp on North Point Rd stopped by when we were there and he said it was OK to return any time.

Tags: SAV Observations · SAV Restoration

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