Aerial and Field SAV Observations

I surveyed about 2.5 miles of tidal Mattawoman Creek by kayak on 9-17-11, starting at the kayak launch at the end of Mattingly Road and paddling upstream, not quite reaching the bridge across the creek. The trip included high tide so it was only near the end of the trip that SAV was visible at the surface, but I found some almost everywhere I raked in the shallows.

Almost all of the SAV I found was hydrilla (Hv), with milfoil (Ms) and coontail (Cd) mixed with it in a few locations, and spiny naiad (Nm) mixed with it once. In the shallows, almost all of the SAV was mixed with either emergent or floating aquatic vegetation (EAV and FAV), although at the few places where I checked, Hv extended deeper than the EAV/FAV. See the map of the survey with species found labeled.

An interesting thing about the hydrilla beds on this creek is that they have a light signature in aerial photos, as opposed to the more usual dark signature that I’ve seen in photos of other areas. I found some of the densest beds next to a string of dredge islands, from waypoints 432 to 433 on my survey map. Dave Wilcox sent me the section of the 2011 SAV survey photo that shows those islands with the approximate bed outline drawn, which agrees well with what I saw. I saw additional Hv at waypoints 416 & 417 on the other side of the islands, but where SAV is mixed with a lot of EAV/FAV it is hard to identify it in aerial photos, so the aerial survey underestimates the amount of SAV where it is mixed with EAV/FAV.

The SAV I found here was almost exactly the same species that I found on the tidal fresh Patuxent on 6-25-11; see my report here. The main difference was that the SAV was much more abundant and widely distributed on Mattawoman Creek than on the Patuxent. Also, the Hv on Mattawoman Creek (see photo) had smaller leaves and more closely spaced whorls than what I saw on the Patuxent in June.

Another difference was that we saw a lot more birds on Mattawoman Creek than on the Patuxent, probably because it had more fish. On Mattawoman we had one or more great egrets and/or great blue herons in view most of the time, and saw many gulls, terns, and kingfishers, as well as four bald eagles being mobbed by crows and several osprey, all piscivorous birds. The greater number of people fishing that we saw on Mattawoman Creek was also a clue to the fish populations. Most were catching catfish but you can also catch snakeheads there (see link to USDA page about them).

How far can the high flow from a hurricane move SAV wrack? Wrack are the plants that get broken off but float until they end up on a shoreline. It appears they can move pretty far, based on two recent observations.

I walked down to the end of First St in Eastport, Annapolis on 9/15/11, where a small beach faces the mouth of the Severn River. Not surprisingly, there was quite a bit of SAV wrack on the beach, but most of the species I found can’t grow in the Severn because it’s mesohaline and many of them are tidal fresh. Carl Treff sent me photos of most of the same species in SAV wrack from the Magothy River (also mesohaline), taken on 9/17/11 at the Eagle Cove School near the Gibson Island Causeway. The two collection sites are shown on this map that also shows the 2009 SAV mapped in both rivers.  Note that the Magothy site is much farther from the mouth of the river than the Severn site, since Eagle Cove School is on the river side of the narrow peninsula that connects Gibson Island to the mainland.

The first Severn photo shows (left to right) milfoil, wild celery, coontail, hydrilla, and elodea. The second Severn photo shows wild celery and water stargrass. The first Magothy photo shows coontail and milfoil (top) and hydrilla, water stargrass, and wild celery (bottom). The second Magothy photo shows wild celery and milfoil, both very long and surprisingly unbroken if they floated a long way. The card is 12×18″. Thus, of the species I found on the Severn, only elodea was missing in the Magothy wrack.

While milfoil and elodea have been found in the Severn, both are uncommon, and the others are either very rare (wild celery, last recorded in 1979) or unknown here (water stargrass, coontail and hydrilla). Wild celery, milfoil, and elodea are fairly common on the Magothy, the next river north, but the closest location where I’ve found coontail north of the Severn was in Longs Creek at the mouth of Back River; we did not see it in Shallow Creek this year. To find records of hydrilla to the north, you have to go to the upper Gunpowder and the Bird River which is upstream of that, mapped in 2009 on Quad 7, left edge and Quad 6, lower right. Water stargrass, on the other hand, probably came from Susquehanna Flats, where it was reported near the southern tip of the large bed in the 2008 map from Quad 9. It has not been reported (that I could find) in the Gunpowder or Bush rivers or in Romney Creek at Aberdeen on Quad 8 (surveyed in 2000). Thus, In both rivers the wrack probably came from somewhere near Susquehanna Flats with all the flow from Tropical Storm Lee, probably after the Conowingo gates were opened on 9/9.

Piscataway Park is on the tidal fresh Potomac River, just downriver from Piscataway Creek and across from Mount Vernon (see map).  Two stretches of eroding shoreline at the park were slated for living shoreline restoration projects, so vegetation transect surveys (sampling SAV in water, and wetland and other plants on land) were designed and started in 2006 to see if the nearby vegetation changed after the project was done. The two restored stretches are called North Coast, about 1,900 feet long, and South Coast, about 1,000 feet long, with an unrestored section of shoreline between them, protected by rock-filled gabions, that was not sampled. Together the two sections of living shoreline restored 2.2 acres of tidal marsh and protected 30 acres of freshwater marsh. You can read about plans for the project here, and see a gallery of photos from construction here. This is a preliminary report on the results of the SAV surveys only; we’ll prepare a more detailed report later.

I organized SAV surveys there on 6/2/11 as part of “NOAA Restoration Day,” which enables NOAA’s office workers to get out in the field once a year and do hands-on work for the resources that are the focus of most of our work. We repeated the same surveys on 7/25/11 because they were done in mid-July in past years (2006, 2009, and 2010). The surveys were designed in 2006 by my colleague Rich Takacs, who works for NOAA’s Restoration Center in Annapolis, and Karen Jensen Miles, who works in the park as the Program Director for the Alice Ferguson Foundation, which manages the Living Shoreline at Piscataway Park with the National Park Service.

The SAV surveys use transects spaced 100 feet apart along both stretches of restored shoreline, perpendicular to shore, sampled once a year in July. The locations of the sample points on the two stretches of shoreline are shown on this Google map I made. (The transects also extend onto land but we did not survey that part or analyze those data.) Surveys are done by wading (because all of the areas are shallow) with a tape measure and clipboard, and were done visually until 2011 because the grasses were so dense that raking was not needed or useful. However, the grasses were so short on 6/2/11 that bamboo shrub rakes were used for all sampling, and the rakes were also used on 7/25/11 when the grasses were not growing to the surface. This change may have increased the species diversity and/or % occurrence values in 2011. Each transect was walked from shore by 1-3 people with a tape measure; when SAV were first encountered the distance, species and estimated overall % cover were recorded. The walking continued up to about 100 feet (or a bit more) offshore and each time the species composition or density changed, that change and the distance was noted. Usually the survey stopped when the grasses reached 100% cover and further walking was difficult, which was often less than 100 feet from shore. Thus, we did not survey all of the SAV that was present, just the less dense band near shore. The VIMS ground survey SAV species abbreviations were used. Nancy Rybicki (USGS), Kendra Scheminant (Bayland Consultants), and Lauren Land (NOAA) helped me and Karen lead the teams that did the June surveys.

The living shoreline was built in early 2010, from January through June (see newspaper story from Nov. 2010), so the 2006 and 2009 surveys were done before, and the 2010 and 2011 surveys were done after it was built. We did not sample a control site, so any differences between the pre- and post-restoration surveys could be due to changes in the species composition and abundance of SAV in that whole stretch of the river, not due to any effects of the project on the SAV. Also, the two sections of shoreline studied are quite close to two sources of SAV propagules: (1) the North Coast is close to the very large and dense SAV bed that filled most of Piscataway Creek in recent years (see the VIMS SAV map of this area from 2007, the most recent map with ground truth data), so changes in the species composition and abundance in that creek probably affected the beds sampled in this survey at the north coast. (2) the South Coast includes two tidal creeks, Accokeek Creek and a smaller unnamed creek, which drain onto the beach. The upper nontidal reaches of those creeks probably provide a reservoir for lower-salinity SAV species, and these upstream beds would wash SAV propagules down the beach.

There are some changes in the graph of total species diversity by site (North and South) by year; some of these are probably the result of changes in the SAV area nearby (see composite image of the 5 VIMS SAV maps from 2006-2010). North Coast had a sharp drop from 8 to 1 species, but that drop occurred before the project was built (2006 to 2009).  The living shoreline was built in 2010 and finished before the flight for the SAV map was made on 9/1/10. The number of species at the North Coast remained low (2) in 2010, but rose to 6 in July 2011 (not counting the 3 additional species we found only in June). The huge drop in SAV area in Piscataway Creek from 2008 (see map) to 2009 (see map) may have contributed to the drop in diversity at North Coast in 2009, since (as noted above) the huge beds in that creek probably contributed SAV propagules to the area we surveyed on the mainstem along the North Coast. There was some increase in SAV area in that creek in 2010, but also a sharp decline in the SAV area mapped off the living shoreline that year (see map). SAV diversity was more consistent over time at the South Coast, varying from 6-8 species.

Bar graphs of species composition by site for each year reflect these changes in diversity. The 2006 and 2009 graphs mainly differ in the reduced number of red bars (North Coast) in the 2009 graph compared to 2006; the blue bars (South Coast) changed much less, except some of the % occurrence values were higher in 2009, and the Naiads were lumped as “N” in 2006 but mostly split by species in 2009 (Ngu and Nm). The 6 species on the right side of these graphs all occur in this part of the Potomac but are rare at this site, or (in the case of Zp) tend to die back before the surveys are done. Where SAV beds are very dense, as they usually are on this shore, it can be very hard to find the rarer species, especially when rakes are not used. In the 2010 graph (upper figure), the % occurrence values at the South Coast dropped back to near 2006 levels for most species, except the abundance of Cd and Va was up there, and Va continued to dominate at the North Coast, with a bit of Hd found at one point. We found more species in 2011, partly because we used rakes for the first time, we sampled twice (early June and late July), and we had more people sampling. In the July 2011 graph (lower figure), the South Coast data had two minor changes from 2010, with Nm replacing Ngu in the naiad family, and the occurrence of Hv went up in 2011. North Coast had many more species in 2011 (6 vs. 2 in 2010), with Hv the most common of the species added (much more common than it was in 2006), but we still found Va at almost every spot sampled.

The data from our June 2, 2011 surveys were not included in our interannual comparisons above because they were collected over a month earlier than the other data, but they provide some interesting comparisons, as shown in the bar graph of species composition by site for 6-2-11. The most notable difference between this and the July 2011 graph (lower figure) is that in June we found three species not found in July: C, Pcr, and Ec (En). Ec (En) or Elodea in the tidal Chesapeake was once thought to be all E. canadensis, but now has been shown to be the similar-looking E. nuttallii in the Potomac, based on genetic research in press done by Nancy Rybicki. We found all three of these species at South Coast and all but Pcr at North Coast. Either these species were hidden under other plants by late July (which is likely), or they had died back by then. At South Coast, Cd was much more common in the June survey, while Hd was absent in June and present in July, probably because it had not come up yet in June.

The mean distance from shore to the first SAV was usually fairly constant at about 10-30 feet, as expected if this were set by physical factors like exposure at low tide and breakage of plants from greater wave action near shore. However, the graph shows that this distance was about 3 times higher in 2009, for reasons that are not clear.  It’s possible that filamentous algae (see below) smothered the shallower plants in 2009, and there was a huge SAV dieback in nearby Piscataway Creek that year (see composite of 2006-2010 VIMS maps), but there was no note about algae in the field notes from 2009, and Rich did not recall abundant algae that year. The distance to the first SAV was always slightly higher at the North Coast than the South, probably because the North Coast is more exposed, with its northern part having a longer fetch running along the river (to the north) rather than across the river.

One of the issues with sampling SAV at Piscataway (and in other tidal fresh regions) is the presence of dense mats of filamentous algae, Plectonema (formerly Lyngbya) wollei, mainly in the shallows (see this photo from NC). Sometimes what appears to be plants growing through it turn out to be plant fragments trapped in it with no live, rooted SAV underneath. This makes it hard to determine where the live SAV starts as you walk out from shore, and it also complicates the interpretation of the aerial photos for the VIMS SAV survey.

Greetings SAV friends and colleagues! It looks like another summer is about to end and as in past years, there seems to be both good news and not so good news with SAV in the bay. We have made good progress in acquiring photography. We completed the entire lower bay by the end of June, and coastal bays by early July. We were also making good progress for many of the lower salinity regions of the bay and tributaries, but Irene has put an abrupt halt to further efforts until the water clears.

Our staff is processing the imagery and will be adding it to the interactive map (http://www.vims.edu/bio/sav/maps) as it becomes available. Our SAV blog (http://thumper-web.vims.edu/bio/sav/wordpress/) is up and running and we already have a number of interesting observations. Please let us know what you are seeing out there! Various Riverkeepers have really been a big help in recent weeks.

Here are some observations from the areas that we have photographed so far:

SAV abundance, both eelgrass and widgeongrass, in the lower bay is down quite a bit, most likely a result of the effects of the hot summer in 2010. It looks like we may be down as much as 40% from 2010 when we acquired the photography just prior to the onset of that heat spell. The dense beds in many of the lower bay locations were still present, e.g. Poquoson Flats, Mobjack Bay, Tangier and Smith Islands, but there were big changes throughout the region. Interesting, at the same time, widgeongrass had some robust and very dense flowering shoots in many areas of the lower bay.

SAV in the MD coastal bays looks good except in Isle of Wight and Assawoman bays. Here, widgeongrass appears to absent in many places. In the Virginia coastal bays at our restoration sites eelgrass beds are once again doing really well.

James River (flown Aug 1 and 16) – while we have noted that SAV has colonized many of the smaller tributaries (e.g. Powell’s and Herring Creek near Hopewell, and the Chickahominy River has an abundance of SAV), for the first time since we started the survey back in 1978, SAV is present in the mainstem James. The bed is located above the mouth of the Chickahominy River along the James north shore off Tyler Creek just up from Sturgeon Pt. We were lucky to have the James Riverkeeper check it out and he noted this large bed, about ¾ mile long and probably 100 yards wide, was dominated by Naiads. And Queens Creek, up from this bed which had little last year, was loaded with SAV (both hydrilla and naiad) right at the mouth of the creek. We also noted a small bed on the mainstem off a marsh adjacent to Presque Isle.

Pamunkey and Mattaponi rivers (flown Aug. 1 and 16) are again loaded with SAV in the usual places. All prior years’ ground observations have shown it is mostly hydrilla.

Choptank River (flown Aug. 23) – there is definitely more SAV in many of the tribs (Harris and Broad creeks) than we have seen in previous years. We have heard from a number of sources, especially the riverkeeper Drew Koslow, that widgeongrass has re-appeared in places it has not been in years.

Mainstem from the mouth of the Choptank to Eastern Bay – there is lots of SAV from Harbor Cove to Claiborne. We did not detect any SAV off Poplar Island.

Eastern Bay and tribs (Miles and Wye rivers) (flown Aug 23) – there is much more SAV than in previous years in many areas – probably all widgeongrass.

Eastern Neck and Chester River – WOW!! The large shoal along the western side of the area is full of SAV – I haven’t seen this much since 2005, and many of the small coves in and around Eastern Neck (see photo) have SAV’s. Chester River proper has very little except at Robins Pond and a few other locations.

Potomac River - lower sections from 301 bridge to mouth (flown July 28) – there is very little SAV but we have not gotten imagery for the St Mary’s where most of the SAV was in the last few years. SAV has returned to Nanjemoy (flown Aug. 24) but only the upper part. Potomac Creek is loaded with SAV but appears to be down in Aquia Creek. The mainstem Potomac from Maryland Pt to Mattawoman and Aquia Creek to Neabsco Creek looks okay although SAV in some places appears to be less than in 2010.

Western shore tribs (flown Aug. 24) – the only river that appears to have any significant SAV is in the Severn although its abundance is down. SAV in Shallow Creek (see photo) looks good except it is down from last year although Peter Bergstrom reports greater species diversity this year.

We would love to hear from more of you if you have been out in the shallows!

Cheers

JJ

Lee Karrh and I checked out the Susquehanna Flats today to see how the SAV faired after Hurricane Irene.  The sun was shining and the winds were light, a stark contrast from this weekend.  We launched out of Turner’s Creek on the Sassafras and made the run to the south side of the Flats proper.  The waters around the boat ramp on Turner’s Creek and near Ordinary Point were quite “minty” with a blue-green algal bloom (samples were collected and delivered to DNR’s algal experts).  Water clarity on the south side of the Flats wasn’t great. Secchi depths were between 1 and 1.3m in areas we can typically see bottom in 3+ meters of water, but the SAV appeared healthy.  We continued to the center of the monster bed near the continuous monitoring station and then towards Havre de Grace where Secchi depths were a bit worse (0.65 - 0.7m).  Va, Ms and Hd were present and all were in different stages of flower. The beds were quite dense (Class 4 75 - 100% cover) and there were no obvious signs of scour or burial. There was also a fair amount of pollen on the surface of the water, but we couldn’t determine if it was from aquatic or terrestial plants.  The filamentous algae Plectonema (Lyngbya) wollei which was present earlier in the year was absent.

The day after the earthquake was a good day to survey SAV in Shallow Creek with near-perfect weather and fairly low tides. The water could have been clearer (Secchi was 0.45 m) but it’s usually murky here, and the salinity was 8 ppt.  This graph compares those values to what we measured here in past years; clarity this year was slightly below the long-term mean (0.52 m) while salinity was slightly above it (7.6 ppt). I paddled with Howard Weinberg, a GIS specialist who works for UMCES at the Chesapeake Bay Program, who helped with the planting here in 2000 and had not been back since.

I supervised small-scale SAV planting events here in 1999, 2000, and 2001, and helped with a MD DNR-led planting event in the same area in 2003. I try to check the beds every year since they have done so well. (For example, see my report from 2009 here, the year with the most extensive SAV cover.) We planted about half wild celery (Va) and the rest was redhead grass (Ppf) and sago pondweed (Ppc), but none of the Ppc seemed to survive, although the creek has some now. We found one small naturally occurring bed of Va in the outer cove before we planted in 1999, but genetic testing by Mike Lloyd and others showed that its genetics differed from the Va in the area we planted, showing that much of the Va in the creek is from what we planted rather than what was already there. We found no Ppf in the creek before we planted it there, so we assume that the Ppf there now is from what we planted, although its seeds can of course be moved by waterfowl.

The survey map from our visit has numbered areas (1-8) that I’ll refer to below. All the marked waypoints had some SAV. The same map and almost 70 photos of the SAV we found are in this web album (with captions) from the trip. The album includes the VIMS SAV maps of the creek (made for me by Dave Wilcox, thanks) from 2008-2010, which show that 2009 had the peak SAV area. Dave also calculated the mapped SAV area adjacent to where we planted in area 1, out to the channel and from the RR causeway up the creek to the launch point, and this graph of SAV area by year in that area showed that it peaked at almost 9 ha in 2009, after starting from the roughly 0.02 ha that we planted, but of course some of that 2009 area was milfoil (Ms) that we did not plant.

1. This shore was the main planting area in 1999 & 2000 and the only planting area in 2001 & 2003. We found similar SAV to what we found here last year: clumps of Ppf in the shallows (see photo, almost up to the edge of the marsh plants) changing to solid beds of Va (see photo) almost out the the channel, with some areas with mixed species. We also found slender pondweed (Ppu, see photo) at one spot in the shallows with Ppf, and also some Ppc (see photo showing its characteristic clumping of leaves) in a few other spots in the shallows.

2. The outer cove had beds of Va & Ppc in its mouth, and species diversity and density increased as we moved up the cove. First we checked the area where we planted SAV in 2000, at waypoints 353 & 354, on the south side of the cove. We found The Va and Ppf that we planted plus Ppc and quite a bit of curly pondweed (Pcr, see photo), a low-salinity species that is usually rare in this creek, probably more common this year due to the big spring freshet. As we moved up the cove the species diversity increased as common elodea (Ec) appeared, and at one spot (355) we found 6 of the 7 species that we found all day in one spot, all but Ppf: Va, Ms, Pcr, Ppc, quite a bit of Ppu, and a fairly deep carpet of Ec (see photo; Ec rarely grows to the surface in my experience but it can be quite dense). We did not have time to explore to the upper end but it appeared to have SAV all the way up. We left via the north shore of the cove, where there had been some Va before we started planting it (so we did not plant any there), and there is still a dense bed of Va with a bit of Ms at that same spot (see photo; waypoint 362).

3. SAV has spread in the shallows just outside the mouth of the creek into this area (349-351); extent seemed to similar to what was mapped recently. Va, Ppc, and Ppf were present but mostly Va. The Va here had more filamentous algae than most of the beds in the creek (see photo).

4. There is an old railroad bed that used to bring trains across the creek to the beach at what is now North Point State Park, that forms the southern edge of this cove (the outer cove is outside the RR bed).  This area had less SAV today than it had in recent years when it was completely full of SAV; this year there was a line near the mouth of the creek where the dense SAV ended, which we roughly followed as we paddled (see photo). The cove contained Va and Ms with less Ppf and Ppc.

5. The next cove up the creek had only Va and Ms, and also had a line across its mouth where the SAV appeared to end, also showing less SAV than last year.

6. The SAV started even a bit farther up this cove, and was also limited to Ms and Va, mostly Ms after we crossed the outer edge, with some Ppc. See a photo of one of the Ms beds here.

6a. The last cove on the right had Va with some Ms and Pcr, but the beds were patchy, much less extensive than last year.

7. After crossing to the western shore of the upper creek we found a bit more wild celery (Va), mixed with Ms, as the wind picked up (see photo of one of the beds). Both were generally shallow, and SAV was less extensive than in 2009-2010 (but more than what was mapped in 2008). A flock of Canada geese had been feeding in this area before we paddled over to it. I last saw a mute swan in this creek in 2009, and I used to see flocks of 6 or more here in the past (usually in area 4), which is good news for the SAV here.

8. This peninsula is where several watermen live on this creek, and the dredging of the channel on its north side  by USACE in about 1998 was what led to the funding for SAV planting here, as compensation for disturbing some milfoil (Ms) that was in the channel. Today there was a very shallow patch of Ms next to that channel at 396, and clumps of Va & Ms with Ppu at one spot along the point at the end of the peninsula (we also found Ppu in areas 1 & 2).

Launch–I checked for SAV along the bulkhead next to the ramp as we returned here and found much less SAV than was here in 2008-2010, especially than in 2009 when this whole area had SAV.  This year the SAV was limited here to a few sparse clumps of Ms and Va; this photo of Howard returning to the launch site shows no flat water, while in 2009, most of this area had dense SAV, as was visible in this photo from 2009 of roughly the same area (looking across rather than up that cove).

Mark Lewandowski plan to go soon to survey the other area where wild celery & redhead grass survived and spread after planting, in Longs Cove at Rocky Point Park at the mouth of the Back River. See my report from that creek from 2010.

I repeated the annual Magothy SAV transects that I started in 2007 on 8-9-11, with help from some of the folks associated with the Magothy River Association who helped before (Carl Treff, in his boat, and Tim Decker) and a new helper, Sally Hornor.  Here is my report on the surveys we did of the same transects in 2010.

We visited the same 4 fixed transects at around low tide (see map). We used the modified oyster tongs provided by MD DNR to take 3 replicate grabs at each of 6 points along each transect, spaced 10 m apart starting about 10 m off the shore (and thus ending about 60 m off shore).

We found slightly less total SAV volume than last year (727 ml this year vs. 860 ml last year, see graph which includes Severn data). This volume was down from over 2500 ml in 2008, but much higher than the low point of 282 ml in 2009.  On the bright side, two of the transects that had little or no SAV last year, Gibson Island and Stonington, had the majority of the SAV volume this year (551 of 727 ml). However, it was all one species, sago pondweed (Ppc, see below), a species that tends to come and go in the Magothy, and thus is less persistent over time than the usual common species, widgeongrass (Rm) and  redhead grass (Ppf),

Species diversity in 2011 was limited to 2 species, as it was last year, but they were Sago pondweed and redhead grass this year, compared to widgeongrass and redhead grass last year. The abundance of redhead grass appears to be way down this year; we only found it at one transect, South Ferry Pt (same as last year), but we only found it in 2 of the 18 grab samples there, with 27 ml in one and 1 ml in the other. In 2010 we found a total of 803 ml of redhead grass in 12 of 18 grabs there (all of the shallower ones).

This year I calculated the percent of grabs that had any SAV to estimate its patchiness. When we collect samples we don’t aim for clumps of grass (if any are visible) so this should be an unbiased estimate of patchiness.  The graph of the percent of grabs that had any SAV (for both rivers over all years, 2007-2011) shows a sharp increase in the Magothy this year to near 60%, which is good news. However, this figure is down in both rivers since the peak in the first year (2007) near 80%, showing that the beds sampled are becoming patchier over time.

One puzzling result, comparing these Magothy results to the Severn 2011 results from about 2 weeks earlier, is that the Magothy was dominated by sago pondweed, while the Severn was dominated by widgeongrass. The two species can look very similar, but some of the plants in both rivers had seeds developing, which look quite different (see the sago seeds on the Magothy plants), and the Magothy plants all had the “clumping” of leaves out of water characteristic of sago pondweed, and had clear bayonets on the plants checked. The widgeongrass on the Severn was not clumped (see photo). The two species have occurred together in these rivers in the past, so it is puzzling that each river had only one of them. Also, since widgeongrass is usually more common than sago pondweed in both rivers, it seems that whatever conditions favored an increase in sago pondweed in the Magothy (the pulse of low spring salinity in 2011?) should do the same in the adjacent Severn. It’s possible that both rivers have the “missing” species this year in spots we did not sample.

Mill Creek on Magothy River had a 3 million gallon sewage spill in its lower nontidal reaches in December 2005, that added a large amount of sediment to its upper tidal reaches. Its uppermost tidal reaches were dredged last winter (2010-2011) to remove some of that sediment and restore the previous boat access. There were “SAV shelves” dredged to -0.5 ft MLLW next to the channel that were designed for SAV planting, with even shallower shelves next to those for wetland planting. The wetland planting was done by contractors, and I worked with Mark Lewandowski and Brooke Landry , MD DNR, local girl scouts, and the Magothy River Association (MRA) to organize the volunteers who grew and planted wild celery in the shelves. Photos from the 2nd planting in late June are in this Picasa web album.

We had tried wild celery planting in the Magothy before without success, but those attempts were on the mainstem; we had never tried it this far up a creek. Project costs were covered by the MRA and MD DNR (which already had SAV growing gear) and the Anne Arundel County Dept. of Public Works. Steve Ailstock, Mike Norman, and other staff from Anne Arundel Community College’s Environmental Center provided field support and will do additional planting later.

We set up 4 exclosures on SAV shelves on the sunny side of the creek, next to a pier where we had permission for overland access (see map; letters were assigned in the order we planted them, A-D). This allowed us to plant there and check the plants by boat or by land. The other shore also had SAV shelves but they are in the shade of overhanging trees most of the day.

Mark and Brooke brought the plants grown in schools through Bay Grasses in Classes on June 8 and they, AACC staff, and Alex Page planted them. The students who grew them were not allowed to plant them since we could not work out overland access for them. The plants grown by Girl Scouts and MRA volunteers were planted on 6/24-25 by community volunteers, supervised by a Girl Scout, Alexanna Page, as her Gold project, with assistance from me, Brooke & Mark. The mucky sediments made planting challenging; in some areas the planters had to kneel to keep from sinking in too far, and then it was hard to move once they finished planting a row. Three of the exclosures got about 80 cat litter pans of wild celery each, while the fourth and last one (D) only got 27 since that was all we had left that day (6/25).

Mark and I checked the plants yesterday (on 8/22), about 2 months after the second planting, and found the lowest tide we had ever seen, so it was easy to check survival of the SAV. All 4 exclosures (A-D, in the order we planted them) had some wild celery left, with between 5-20% cover. The Secchi depths (measured weekly at the same pier we used for access) have all been low since we planted (maximum 0.45 m, several weeks had only 0.2 m, plants need about 1 m to survive) so I expected to find a lot less growth than we did in July, and was pleasantly surprised to find some increases. The water was very murky and the tide was higher during our July visit, making it harder to see the plants then, even with a view scope.

All of the exclosures had 60% cover when planted except D, the last one planted on 6/25, had only 40% since we did not have enough plants to fill it up.  This graph shows the percent cover over time for each of the 4 areas. Mark & I plant to visit once more this year, probably in Sept.

The photos of the plants I took on 8/22 are online at this link. Note that one of the exclosures (B, the farthest upstream) had sediment deposition after we planted there so that only the deep edge remained deep enough to support SAV. This is one of the risks of using very shallow shelves for SAV planting, especially where they are close to the freshwater inflow. The photos also show the adjacent wetland plants, about half of which appeared to be gone, presumably from grazing: the remaining ones appear to be grazed, and the bare areas had grazed plants when we visited in mid-July.

I surveyed the shoreline around Frying Pan and from Church Creek to the bridge on 8/20/2011.  SAV has returned there also, the most I have seen there in over 5 years.  From the bridge, as you go around the point from the narrows and enter Frying Pan there are patches of elodea and wigeon grass all along the shore, all the way to Boxes Point.  In some places they are quite dense.  From the shore they extend out about 25 feet, except in a couple of small inlets/coves that are more covered.  I saw no redhead grass in this section, and one or two millfoil plants.  Secchi depths were about .5 meter.

On the return I went across the mouth of Church Creek and along the shoreline between Church Creek and the bridge.  Across the mouth of Church Creek there were patches of elodea and ruppia.  These patches coalesed into a canopy covered bed as I proceeded west,

extending from the mouth of the creek almost to the bridge, at least 150 feet from the shore.  I estimate at least 5 acres of 70-80% coverage.  This bed also included some small patches of millfoil, and one small patch of redhead grass.

Earlier today, South Riverkeeper, Diana Muller, and two other Federation staffers found wild celery (Vallisneria americana) and what was likely parrotfeather (Myriophyllum brasiliene) in Selby Bay off the South River.  Generally this area is brackish, but as of right now the salinity hovers around 5.  Parrotfeather exists in abundance in some of the fresh, non-tidal tribs to the river, but is not often seen in tidewater.  It has been many years since the last report of wild celery in the South.