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Submerged Aquatic Vegetation (SAV) update. Peter Bergstrom, NOAA Chesapeake Bay Office MASC Workshop, 10/18/07. SAV survey status & results. 2007 areas will not be ready at least until February Flight lines completed only recently—see map, next slide

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Submerged aquatic vegetation sav update

Submerged Aquatic Vegetation (SAV) update

Peter Bergstrom, NOAA Chesapeake Bay Office

MASC Workshop, 10/18/07

10/18/2007


Sav survey status results
SAV survey status & results

  • 2007 areas will not be ready at least until February

    • Flight lines completed only recently—see map, next slide

  • SAV transects in several rivers; better ground survey data

    • Done for years by Nancy Rybicki’s group in the Potomac; can show patterns by species (see examples below)

    • 2007 transects started in MD by riverkeepers and volunteers in Bush, Patuxent, Chester, West/Rhode, Severn, South and Magothy rivers

    • VA transects done by VIMS in 2006-07 in York (6 sites) and Mobjack Bay (3 sites); also about 100 sites on both VA shores surveyed 2006-07 for eelgrass abundance

  • 2006 report incorporates new interactive map

    • This now contains the ground truth data; these are no longer shown on the quad maps

  • 2006 results show declines from 2004 & 2005 in all zones, including MD & VA coastal bays—why?

10/18/2007


2007

Flight

Lines (all

are done

now)

10/18/2007


Collecting sav transect data
Collecting SAV transect data

Tools: oyster tongs, graduated

cylinders, GPS, buoys

10/18/2007


Sav patterns by species from potomac transect data
SAV patterns by species from Potomac transect data

Peak in Hydrilla moved downriver

Source: Nancy Rybicki, USGS

More TN means less species diversity

10/18/2007


Sample transect data abundance by species by distance from shore
Sample transect data: abundance by species by distance from shore

10/18/2007



Recent sav patterns
Recent SAV patterns

  • Baywide area and some zones increased during 2001-2002 drought

    • Increased in higher salinity zones only (mid and lower Bay)

  • SAV area declined baywide and in all zones, including coastal bays, in 2006

    • In lower Bay, this was delayed response to 2005 hot summer (photos taken in spring)

    • May be some increases in 2007

10/18/2007


Baywide area peaked in 2002 declined in 2006
Baywide area peaked in 2002, declined in 2006

Drought

Not including Coastal bays

10/18/2007


Sav area declined in all zones in 2006
SAV area declined in all zones in 2006

Coastal bays not surveyed in 2005; similar declines 05-06 in other zones

10/18/2007


Sav area by zone through 2006 upper bay
SAV Area by zone through 2006 (upper Bay)

May be up in 2007

(Flats, Bush, Gun-

powder very healthy)

Drought

Probably down in 2007

(very little in Chester,

Eastern Bay, Choptank,

or lower Potomac)

10/18/2007


Area by zone through 2006 lower coastal bays
Area by zone through 2006 (lower & coastal bays)

Drought

Up slightly in 2007 (2006

drop caused by 2005

summer heat)

May be down in

2007 (only healthy

beds near inlets)

10/18/2007


Why is sav declining baywide
Why is SAV declining baywide?

  • Declining water clarity

  • Are water temperatures increasing?

    • either on average, or the summer peaks are getting higher & longer?

    • Extra-high peak preceded 2005 eelgrass dieback, lower Bay (see next slide)

10/18/2007


Warmer water in 2005 preceded eelgrass dieback
Warmer water in 2005 preceded eelgrass dieback

Source: Bob Orth, VIMS

10/18/2007


The future of sav in the bay
The future of SAV in the Bay

  • If summer water temperatures keep climbing, eelgrass (Zostera marina) will continue to have trouble

  • If water clarity keeps declining, all species will have trouble

  • So, what can we do to increase SAV area?

    • SAV planting -139 acres planted to date in Bay, but success is low. Some of planted beds are present & expanding, though (6-7 sites)

    • Improve water clarity - how??

    • Introduce other SAV species that can tolerate higher temperatures and/or lower water clarity?

      • Shoal grass, Halodule wrightii, grows from NC south at present, BUT its minimum salinity is 18 ppt vs. 10 ppt for eelgrass, so it could not really replace eelgrass

      • Japanese eelgrass, Zostera japonica, is naturalized in Pacific NW, tolerates salinity lower than Z. marina, and may hold promise for the Chesapeake (need to know its ecology better)

10/18/2007


Zostera japonica images
Zostera japonica images

Zostera at Padilla Bay, WA

Intertidal Z. japonica

Z. marina

Z. japonica

Intertidal Z. japonica in Japan

Z. japonica

10/18/2007


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