Oysters, reef restoration and water quality:
A Chesapeake Bay perspective

M. Lisa Kellogg
Virginia Institute of Marine Sc...
Increasing Interest in Oysters and WQ
Why?
• Population decline

- < 1% historic levels

• Failure to meet WQ goals
• EPA-...
The Promise of Oyster Reef Restoration

Source: Tom Toles (2013) The Washington Post.
Oysters and Nitrogen Cycling
Oysters don’t filter nitrogen, they consume phytoplankton
Three primary
pathways oysters can
...
Oysters and N Cycling: What We Know…
NCBO – Sponsored Workshop
Jan. 10 – 11, 2013
Wachapreague, VA

Purpose: To gather exp...
Oysters and N Cycling: What We Know…
Long-term burial
• No published rates
- Ongoing analyses of data from
reefs in North ...
Oysters and N Cycling: What We Know…
Assimilation
• Tissue N = 8.22 ± 0.89% of dry wt. for mid- and NE-Atlantic
- 4 studie...
Oysters and N Cycling: What We Know…
Assimilation
• Reefs vs. aquaculture
- Aquaculture harvest removes N from aquatic env...
- Net annual
enhancement of
2.7-55.6 g m-2 y-1
(24-496 lbs. acre-1 y-1)
- Rates within a single
site can vary by ≥2
orders...
Oysters and N Cycling: What We Know…
Denitrification
- No evidence yet for net
annual enhancement
- All data from floating...
Impacts on WQ: Choptank River, MD Example
Measured denitrification rates for a
successfully restored oyster reef
• Subtida...
Impacts on WQ: Choptank River, MD Example
Location vs. goals

Harris Creek restoration:
~$31 million over 5 years
Impacts on WQ: Lynnhaven River, VA Example
TN reduction needed to meet TMDLs:
1,409,078 lbs. y-1
Maximum enhancement of de...
Impacts on WQ: Lynnhaven River, VA Example
TN reduction needed to meet TMDLs:
1,409,078 lbs. y-1
Removal via aquaculture h...
Impacts on WQ: Lynnhaven River, VA Example
A few words of caution and a request:

Source:
http://www.vbgov.com/government/...
Oysters and Water Quality
A few summary points:
1) Oyster reef restoration and/or oyster aquaculture can be
part of the so...
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Lisa Kellogg, "Oysters, reef restoration and water quality: A Chesapeake Bay perspective," Baird Symposium

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Lisa Kellogg, Research Scientist, Virginia Institute of Marine Science

Topic: Shellfish and Water Quality

Published in: Technology, Business
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Transcript of "Lisa Kellogg, "Oysters, reef restoration and water quality: A Chesapeake Bay perspective," Baird Symposium"

  1. 1. Oysters, reef restoration and water quality: A Chesapeake Bay perspective M. Lisa Kellogg Virginia Institute of Marine Science
  2. 2. Increasing Interest in Oysters and WQ Why? • Population decline - < 1% historic levels • Failure to meet WQ goals • EPA-mandated WQ improvements (TMDLs) increasingly expensive - MD and VA - Local governments will pay bulk of costs • Enhancing oyster populations may cost less than other options - Additional benefits Source: US EPA 2003. Economic analysis of nutrient and sediment reduction actions to restore Chesapeake Bay. Annapolis, MD
  3. 3. The Promise of Oyster Reef Restoration Source: Tom Toles (2013) The Washington Post.
  4. 4. Oysters and Nitrogen Cycling Oysters don’t filter nitrogen, they consume phytoplankton Three primary pathways oysters can lower N levels in the water column: 1) Assimilation* - Tissue and shell contain N and P 2) Burial* - Also bury P and sediments 3) Denitrification - For purposes of this talk, “denitrification” = net flux of di-nitrogen gas to atmosphere * Timescale of removal varies widely
  5. 5. Oysters and N Cycling: What We Know… NCBO – Sponsored Workshop Jan. 10 – 11, 2013 Wachapreague, VA Purpose: To gather experts to determine: (1) the best available values for nitrogen removal by oysters; (2) the uncertainty associated with these estimates; and, (3) the data gaps necessary to reduce the uncertainty Moderated by Kevin Sellner (CRC) Participants: Steve Allen (ORP) Iris Anderson (VIMS) Suzy Avvasian (EPA) Peter Bergstrom (NCBO) Bonnie Brown (VCU) Steve Brown (TNC) Mark Brush (VIMS) Ruth Carmichael (USA) Susan Connor (ACOE) Jeff Cornwell (UMCES) Wally Fulweiller (U. Mass) Boze Hancock (TNC) Troy Hartley (VA Sea Grant) Lisa Kellogg (VIMS) Doug Lipton (MD Sea Grant) Mark Luckenbach (VIMS) Fredrika Moser (MD Sea Grant) Annie Murphy (VIMS) Mike Owens (UMCES) Ken Paynter (UMD) Mike Piehler (UNC) B.K. Song (VIMS) Angie Sowers (ACOE) Howard Townsend (NCBO) Bruce Vogt (NCBO) Eric Weissberger (MD DNR) Jim Wesson (VMRC) Stephanie Westby (NCBO) Line zu Ermgassen (Cambridge)
  6. 6. Oysters and N Cycling: What We Know… Long-term burial • No published rates - Ongoing analyses of data from reefs in North Carolina by Mike Piehler, Joel Fodrie, John Grabowski and colleagues
  7. 7. Oysters and N Cycling: What We Know… Assimilation • Tissue N = 8.22 ± 0.89% of dry wt. for mid- and NE-Atlantic - 4 studies; 14 tributaries or subestuaries; MD, VA, MA and NH - But Mobile Bay, AL Tissue N = 11.8% N • Shell N = 0.19-0.21% of dry wt. - 2 studies from Chesapeake Bay • Reefs vs. aquaculture - 2 studies from Chesapeake Bay - Enhancement of standing-stock assimilation on reefs can be high • • • 95 g N m-2 (848 lbs. acre-1) Non-oyster macrofauna can enhance assimilation by ~50% 47% of total N found in shells of oysters and mussels • Likely results in sequestration for decades, centuries or more Source: Kellogg et al. (2013) Quantifying Nitrogen Removal by Oysters: Workshop Report, NOAA Chesapeake Bay Program Office.
  8. 8. Oysters and N Cycling: What We Know… Assimilation • Reefs vs. aquaculture - Aquaculture harvest removes N from aquatic environment • • Greater proportion of total N in tissue N in shell may be fully or partially removed depending on shell fate Source: Kellogg et al. (2013) Quantifying Nitrogen Removal by Oysters: Workshop Report, NOAA Chesapeake Bay Program Office. Photo credit: Tom Pelton
  9. 9. - Net annual enhancement of 2.7-55.6 g m-2 y-1 (24-496 lbs. acre-1 y-1) - Rates within a single site can vary by ≥2 orders of magnitude - Intertidal rates generally lower than subtidal - Increases non-linearly with oyster biomass - Ongoing studies in RI by Jo Carey and colleagues from EPA, TNC and BU Aerobic Sediments • Many factors interact to influence rates • Reefs (NC, VA & MD) Anaerobic Sediments Denitrification Water Atmosphere Enhancement of N2Column -N Flux (µmol m-2 h-1) Oysters and N Cycling: What We Know… 1800Nitrogen Cycling 1. 2. 3. 4. 5. Uptake Filtration Biodeposition Burial Mineralization 1600 Atmospheric/ Upstream Nitrogen Inputs Legend Nitrogen Piehler and Assimilation Removal A. Smyth (2011) B. Deep burial Sisson et al. (2011) to atmosphere C. Return of N O D. Return of N to atmosphere Smyth et al. (2013) Oxygen Production Kellogg et al. (2013) Phytoplankton/ Kellogg et al. (In prep) Particulate Kellogg et al. (Ongoing)Matter Organic 6. Nitrification 7. Denitrification 8. Anammox 9. DNRA 10. Diffusion 1400 1200 2 2 1 C* 1000 O2 2 Dissolved Organic Nitrogen 400 200 3 Organic Nitrogen B 0 Buried Nitrogen Microphytobenthos 1 5 Ammonium (NH4+) 6 Nitrite (NO2-) 5 100 Ammonium (NH4+) 200 6 1 Nitrate (NO3-) O2 10 10 9 Nitrate (NO3-) 300 7 Nitrite (NO2-) 400 Oyster Biomass (g DW m-2) * Nitrogen cycling pathways resulting in removal assumed to be similar to those shown for sediments Source: Kellogg et al. (2013) Quantifying Nitrogen Removal by Oysters: Workshop Report, NOAA Chesapeake Bay Program Office. O2 Live Oysters Oyster Shell 4 Organic Nitrogen -400 D C 1 10 A 3 0 Biodeposits/ 10 10 A 10 10 -200 10 2 D* Dissolved Inorganic Nitrogen 1 800 600 Nitrogen Gas (N2) Nitrous Oxide (N2O) 7 Nitrous Oxide (N2O) 500 8 7 Nitrogen Gas (N2) 600
  10. 10. Oysters and N Cycling: What We Know… Denitrification - No evidence yet for net annual enhancement - All data from floating aquaculture - Ongoing studies in RI by Jo Carey, Suzy Ayvazian and colleagues at EPA, TNC and BU Enhancement of N2-N Flux (µmol m-2 h-1) • Aquaculture (MD and VA) 1800 1600 Holyoke (2008) Higgins et al. (2013) 1400 1200 1000 800 600 400 200 0 -200 -400 May Jun Jul Aug Month Source: Kellogg et al. (2013) Quantifying Nitrogen Removal by Oysters: Workshop Report, NOAA Chesapeake Bay Program Office. Sep Oct
  11. 11. Impacts on WQ: Choptank River, MD Example Measured denitrification rates for a successfully restored oyster reef • Subtidal reef • Oysters 3-7 years old • High oyster biomass m-2 Estimated annual enhancement: • 55.6 g N2-N m-2 y-1 (496 lbs. N acre-1 y-1) Restoring all suitable bottom: • “Suitable bottom” based on sonar surveys and fine-scale sampling of substratum • 48% of total external N removed Restoration needed to meet TMDL requirements: • 23% of suitable bottom
  12. 12. Impacts on WQ: Choptank River, MD Example Location vs. goals Harris Creek restoration: ~$31 million over 5 years
  13. 13. Impacts on WQ: Lynnhaven River, VA Example TN reduction needed to meet TMDLs: 1,409,078 lbs. y-1 Maximum enhancement of denitrification via reef restoration: ~465 acres of oyster reef in 1894 x 496 lbs. N acre-1 y-1 (Choptank rate) 230,789 lbs. y-1 = 16% of total Actual potential reduction likely 1-2 orders of magnitude lower - Measured nitrogen flux rates in the Lynnhaven River in October suggest rates are ~1/5 of those observed in the Choptank - Actual amount of substratum suitable and available for restoration likely to be significantly lower
  14. 14. Impacts on WQ: Lynnhaven River, VA Example TN reduction needed to meet TMDLs: 1,409,078 lbs. y-1 Removal via aquaculture harvest: ~132 kg N per 1 million harvest-sized oystersa =291 lbs N Scale of aquaculture needed to meet 100% of required reduction: 4.8 billion oysters harvested y-1 X 2 years to reach harvestable size > 9.6 billion oysters in aquaculture 28 million oysters harvested from aquaculture in VA in 2012b Much of Lynnhaven River closed to shellfish harvest Sources: a Higgins et al. (2011) Journal of Environmental Quality 40:271-277 b Murray and Hudson (2013) Virginia Shellfish Aquaculture Situation and Outlook Report
  15. 15. Impacts on WQ: Lynnhaven River, VA Example A few words of caution and a request: Source: http://www.vbgov.com/government/offices/eso/Docu ments/tmdl-local-strategy.pdf, Accessed 11/14/2013
  16. 16. Oysters and Water Quality A few summary points: 1) Oyster reef restoration and/or oyster aquaculture can be part of the solution to water quality problems 2) Need to consider nitrogen removal in terms of enhancement above existing conditions 3) Location of reefs/aquaculture relative to goals is important 4) Need to take into account the scale of the problem to assess feasibility of the proposed solution 5) Need to consider options in context of other costs and benefits 6) We are happy to help you translate our numbers, just ask lkellogg@vims.edu
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