Aerial and Field SAV Observations

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.  This was the first place we found a bit of Elodea (Ec)–distinguished from the more common Hydrilla (Hv) by 3 leaves per whorl that were neither recurved nor visibly toothed (Hydrilla usually has 5 leaves per whorl that are distinctly recurved and toothed).  We also found a bit of Ec in the central Flats bed and at Stump Pt.

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 we also found elsewhere.  We finished at Garrett Island (crossed by the railroad bridge) 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.