Aerial and Field SAV Observations

Peter Bergstrom, NOAA Chesapeake Bay Office

Bob Orth asked me and Diana Muller, the new South Riverkeeper, to check out some dark patches he saw near the MD 450 bridge (see 2008 photo) in the upper limits of the tidal South River, part of Maryland’s Lower Western Shore, south of Annapolis.  Diana and I and two others went there today and brought a kayak to get into the shallows.  As I approached the area of the dark patches in the kayak, I noticed small arrow arum (Peltandra virginica) plants (photos 1, 2) with leaves only 1-2″ long that were just below or slightly above the surface, and realzed these looked like SAV in the aerial photo.  Usually these have larger leaves that are fully emergent, so I’m not sure why these plants had leaves that were smaller and lower in the water than usual.  The same area had cattails and carp jumping–I did not check the salinity but it must be fairly low.

On 7/28/08 DEQ observed a large SAV bed at the mouth of the embayment.

On 7/28/08 DEQ observed prominent SAV beds at the mouth and along the shores of the embayment.  Visible algae was present in the water column.

On 7/28/08 DEQ observed prominent SAV beds above the Rail Road Bridge in the embayment.

On 8/25/08 DEQ observed large SAV beds in Chopawamsic Creek and Quantico Creek embayments.  No visible algae was present.

On 10/06/08 DEQ observed large SAV beds present in the Dogue Creek embayment.  They were located on the right and left sides of the embayment.

On 10/6/08 DEQ observed a large SAV bed near the entance into the Pohick Bay/Gunston Cove embayment.  SAVs had been observed here in the past, but this year the bed is much larger than previous years.

Peter Bergstrom, NOAA Chesapeake Bay Office, 10/1/08 (Quads 30 & 31)

I visited College Creek on 9-29-08 to do water monitoring and check the redhead grass and dark false mussels that were both locally dense on my last visit on 7-24-08.  I found that the redhead grass was much less dense than it was 2 months ago, and that all of the branches that had dark false mussels in July were now covered with a dense carpet of bryozoans.

In July, redhead grass had some dense clumps at 2 sites near the middle of the creek: off the restored St. Johns College shoreline, where it had been planted by DNR Grasses in Classes students, and across the creek between two coves, just below the Rowe Boulevard bridge, where it was not planted.  Redhead grass was still growing in both places on 9-29 (see map) but it was much shorter, sparser, and muddier than it was in July.  I also found a fairly dense patch of Elodea (common waterweed or Ec-see photo) in Peters Cove, the first record for this creek, and the farthest south it has been reported on Maryland’s lower Western shore to my knowledge.  The presence of Ec here is puzzling for two reasons.  First, several people in kayaks looked in exactly the same spot more than once earlier this year and they did not find it, and second, the salinity has been climbing all summer, from 5.6 ppt on the surface nearby in April to 13.5 ppt on 9-29.  Even if this is E. nuttallii, as it probably is at that salinity, elsewhere it tends to expand when salinity is low and contract when it is high.

The mussels were particulary abundant in July in Peters Cove, just above the Rowe bridge, mainly on the undersides of rocks and branches.  On 9-29 all the branches I checked there were covered with dense bryozoans, both on small and large branches.  The only mussels I saw were dead shells on the bottom.  It may be that the recent unusually high salinity promoted the growth of the bryozoans.  This made me realize that mussels have to contend not only with grazers (mainly ducks, I think), but also competitors for hard surfaces (bryozoans, barnacles, etc.).

Peter Bergstrom, NOAA Chesapeake Bay Office (Quads 3, 9, and 10)

I had not been on the Flats since 2005 and my report from that visit was brief.  Secchi depths that day (9/23/05) ranged from 0.7 m at the edge of the “big bed” (435 on the map, now near the middle of a larger bed) to 1.8 m near Fishing Battery (440 on the map).  We were disappointed with this clarity because a week earlier in 2005, DNR staff had been able to see divers in 12 feet of water in the channel.  On a brief visit to Havre de Grace harbor in 2006, I found more species visible there than I’d seen in 2005 (see report).  See also Mike Naylor’s Flats report from Aug. 2006 and two late season reports he made (milfoil was still present) from Dec. 2007.

In 2008 there seems to be much more SAV in the Flats than in 2005, with slightly different species.  We found southern naiad (Ngu), curly pondweed (Pcr), and slender pondweed (Ppu) in 2005 but not in 2008, although we snorkeled in 2005 and not in 2008.  We found redhead grass (Ppf) in 2008 but not in 2005 (see Elk paragraph below).  This year in the Flats there appeared to be more coontail (Cd), wild celery (Va), and water star grass (Hd), and less milfoil (Ms) than in 2005.

First we visited some dense beds north of Fishing Battery, where we found lots of Hd, Va, and Ms, then the beds at Fishing Battery (photo), where we also found Hd, Va, and Ms plus hydrilla (Hv) and spiny naiad, Najas minor (Nm) –see photo and map.  Fishing Battery was one of the most successful Va planting sites that Stan Kollar used in the late 1980’s.

Then we moved to the lower Elk River, to coves on the north side.  We found Ppf in 2008 only in the lower Elk (photos 1, 2), which we did not visit in 2005.  Mike Naylor found Ppf there in 2005 (see report although the Ppf locations in the Elk were not on the map that year).  Va was planted in the lower Elk in the same spot where we found Va and Ppf  (to the left of the pier, 365 on map) by Stan Kollar in the late 1980’s, and in 1995 with Stan, we saw isolated patches of Va (but no Ppf ) in the coves where he planted them (along with some Ms and Ppc; see 1995 map).  Detailed surveys by Stan in 1986-87 & 1989-93 (paper reports only), 1994, 1996, 1997, 1998, 1999 and 2000 also showed Va in this area.  Redhead grass (Ppf) was not reported in the Elk until 2004 (all of the SAV beds shrank in 2002-2003), so where it came from is unclear.  Stan Kollar only planted Ppf (cuttings and rootstocks) in 1984, using plants from Wisconsin which died 2 weeks after planting, plus some plugs transplanted from near Annapolis in 1985 or 1986 that also died quickly.  Stan thinks the Ppf found in the Elk in 2004 may have come via bird or boat from the Gunpowder River/Dundee Creek, where Ppf was first found in 1996 (Quad 14) and became more common in subsequent years.

After the Elk we visited the beds both outside & inside (photo) the breakwater at North Bay.  On Mike Naylor’s visit there in 2005 the SAV was only inside the breakwaters, but now it has spread quite a ways outside–see lower right corner of 2008 aerial photo.  The plants looked much cleaner outside (photo from near outer edge of bed); they were covered with foamy green algae inside (photo) which looks white in the aerial photo.  Species present were the same as in the rest of the Flats (see map); SAV was growing as deep as 1.3 m along the channel through the breakwater, and we found Va up to 1.8 m deep on the outer edge of the bed.  SAV grew right up to the outer edge of the breakwater, suggesting that wave reflection there was not limiting SAV growth.

The size and density of the central Flats bed was amazing.  I first crossed it on 9/15/95 with Stan Kollar, when it was only very sparse milfoil (Ms), and in 2005 it had definite gaps in it.  In this “big bed” this year we crossed from south to north over about 4 miles of near-continuous SAV in 90 min, about as fast as we could motor with prop almost out of water (2-3 knots). The water over most of the bed was quite clear, too clear to get a Secchi depth (water depths were 0.6-0.8 m over most of the bed with the bottom clearly visible).  The SAV was mostly Va, Ms, and Hd in varying proportions, but most plants looked clean (photo of Va) and the gaps were small (photo), and many of the gaps had fish in them.  All the Va seeds were still green (photo).  There seemed to be more Va and cleaner plants at the southern portion, with more Ms (photo), more filamentous algae, and murkier water with some scum as we moved north (photo).  We found some weird looking spheres (photo) near the north end; they may be freshwater bryozoan colonies.  In Aug. 2006, Mike Naylor reported that most of the Flats SAV had a lot of filamentous algae on it, but we only saw this in a few places.

We visited the diverse beds off Stump Pt/Perryville Park, near 12:00 on the clock of the Flats, but did not get in the water so we only found 6 species (we found 12 there in 2005), adding Potamogeton nodosus, Long-leaved pondweed, to the Cd, Va, Hd, Ms, and Ec that were common elsewhere.  We finished at Garrett Island where the bed off the southern tip was all Hydrilla (Hv), visible in the lower left of this 2008 photo, with Cd, Ms, and Va being added as we moved north along the western shore of the island.  North of the island on the eastern shore of the river, just south of I-95 bridge, we found Hv, Ms, Cd, and Nm, with the deep edge of the bed at about 1.9 m.  Back in the Havre de Grace Harbor, a large bed across from the boat ramp (visible in the mid-bottom of the 2008 photo) had Hd, Hv, and Nm.