CHESAPEAKE BAY RESTORATION: History, Lessons Learned, Successes and Major Challenges STAC P ST Pre rese sentatio ion Annapoli lis, MD MD Jun une 201 201 7 • 17 Million people • Mixed land uses • Shallow but seasonally stratified • Estuary “flushes” slowly (4-6 mo) • Many rivers connect land to Bay Large Drainage Basin 14:1 Walt Boynton and Many Colleagues Chesapeake Biological Lab, Center for Environmental Science, Univ MD
A Famous Chesapeake Bay Painting • Clearly, fish were important • Emphasis on shallow waters…and there are lots of these everywhere • CLEAR WATER and SAV…a clear water benthic dominated painting and likely a benthic dominated ecosystem From T. De Bry in Hariot 1588
A John Smith Diet • Traded with natives for corn, venison, fish, oysters, nuts, beans, pumpkins…traded swords for turkeys (a 1 for 1 deal…probably not a good deal for the English) • Tobacco…” it purges the superfluous phlegm and other gross humours and openeth all the pores and passages of the body” from Harriot who died of a nasal tumor in 1621…the 400 year tobacco wars are still with us. • Jamestowners preferred a seaman’s diet of pork, beefe, fish, wheat and barley (even with the ever present worms)…not too adaptive even when hungry • Sturgeon (dried and pounded) • The Starving Time (winter 1609-1610)…cats, dogs, horses and people…this was a very tough life indeed! Hoobler 2006
Patuxe uxent nt Riv iver E r Est stua uary ry Circ irca 1 832 832 “So transparent are its waters that far out from shore you may see, in the openings of the sea- weed forest, on its bottom the flashing sides of the finny tribe as they glide over the pearly sands .” The Old Plantation by Hungerford (1859) Water Quality and Habitat Conditions can be much improved…not to the 1832 condition and that may not be the optimal status
Major Events in Chesapeake Bay History: Science, Management and Politics 1950-60s: Pollution not possible in estuaries because of tidal flushing. The Bay is just fine and productive. Almost no “Estuarine Science” literature available 1960s: There is nothing …and we mean nothing…wrong with Chesapeake Bay. Reports of pollution are false and unpatriotic. You can be fired for this sort of loose talk 1960-70s: The more nutrients we can pour into the Bay the better…farmers know that fertilization is good so lets get on with fertilizing the Bay. About 90% of SAV are gone and the causes are unclear 1970-80s: So, OK estuaries can be polluted…big deal. The only thing needed for restoration is control of PHOSPHORUS and that’s easy. Restoration efforts need to focus on POINT SOURCES 1980-90s: Both NITROGEN and PHOSPHORUS from MANY SOURCES are killing Bay habitats …the bay is nutrient obese and needs a nutrient diet…big time 2000-17: Restoration is hard and expensive. Fears that all aspects of the Bay have long memories proven false…Bay is responsive. However, pathways to restored conditions are not simple….expect some surprises
Nutrient Input Data More Available NOW • Range in N and P loads ~ 2.5 Nutrient Loads to orders of magnitude Estuarine Systems • Inter-annual variability ~2X TN Load (gN m -2 yr -1 ) W. Scheldt • Many USA estuaries show a 34 Boston Harbor 100 33 32 Back River 31 ~2-3X increase during the 29 30 28 1960s-1980s 25 26 27 24 N. San Francisco Bay 23 22 21 19 20 Mobile Bay 18 16 10 Himmerfjarden 14 15 12 11 13 Guadaloupe Bay (dry yr) 10 9 Gulf Riga 7 8 Narragansett (prehistoric) Susquehanna River N Loads 6 5 Typical Terrestrial N Loads 4 3 2 140 1 Buzzards Bay 1 Susquehanna Nutrient Inputs 120 Nitrogen Inputs, Kg N day -1 x 10 3 0.1 1 10 100 100 TP Load (gP m -2 yr -1 ) 80 60 Not all estuaries respond in the same 40 way to nutrient loads (e.g., Chesapeake 20 Bay versus San Francisco Bay) 0 1900 1920 1940 1960 1980 2000 Time, decade periods
N versus P limitation in Chesapeake Bay and other estuaries largely resolved : duel nutrient reduction strategy is often needed Jan Li ght Winter Feb N & P Mar Ni trogen A pr Phosphorus Spring May h t n Jun o M Summer Jul Ni tro gen A ug Sep Fall Oc t N & P N ov Phosphorus Winter Dec Li ght Li ght 0 50 100 150 200 Distance from Ocean (km) F rom F is her et al. (1992)
Solomons Island SAV - 1933
Solomons Island SAV - 1963
Multiple Hypotheses Often Associated with Environmental Issues • Typically the case for water quality, habitat and fishery problems • Lots of “finger pointing” goes on and the basic issue is…It’s not me who done it! • Job of science is to sort out these various ideas
Seagrass Decline in Chesapeake Bay a) Submersed Plants in Upper Bay 100 and Other Coastal Systems 80 % Cover 60 • Sharp decli cline in upper Bay and some tributary Rivers in 40 early 1960’s 20 • Mode dest st re recovery ry since mid- 1980’s 0 • Nut utrie rients a s and d 1900 1920 1940 1960 1980 2000 se sedim diment increase Year turbidity and enhance algal growth on SAV leaves… main cause of decline • A huge ha habita tat t change Adapted from Kemp et al 2005
Shallow Estuarine Systems Respond to Nutrient Loads: Algal Biomass Accumulation • Currently many examples supporting this relationship 160 Shallow Ches Bay tributaries Best Fit Regression 95% Confidence Interval 140 Mattawoman Ck (2005-2010) May-Aug Chlorophyll-a, µg l -1 • Generally stronger Mattawoman Ck (1985-1988) relationships for N 120 than P loading 100 80 • Responses tend to be rapid…several 60 years rather than 40 decades (see red and 20 purple dots for restoration site 0 0.0 0.1 0.2 0.3 0.4 0.5 response) Jan - Mar TN Load, g N m -2 day -1 Boynton et al. 2013
Multiple Factors Involved in Determining Annual- Scale Hypoxia and Other Bay Processes N-Load plus winter N-Load only and summer winds Y. Lee et al
Lets look at Wetlands for a Moment
Nitrogen Burial (g N m -2 yr -1 ) 18 MARSH BURIAL of Landscape 16 Scale PARTICULATE 14 Equal to 107 pounds N NITROGEN 12 per acre per year…for 10 free! 8 • Strong GRADIENT in 6 4 burial across the land 2 – sea interface 0 Tidal Estuaries River Deeper • Rates are LARGE Marshes Deltas Coastal • Strong gradient in 50 Nitrogen Burial (g N m -2 yr -1 ) Patuxent marshes with Small Spatial 40 highest burial close to Scale marsh edge 30 300 pounds N acre -1 year -1 20 10 0 Low High Mid Marsh Greene 2005
A Synthesis based on multiple Syntheses Nitrogen Export: For these estuaries, the percent of TN input exported was inversely related to water residence time • “Give the bugs enough time and they will use and get rid Total N Exported, as % of inputs of it” Scott Nixon • In these budgets internal N losses were via Potomac denitrification and long-term N burial…fish extraction losses were small Nixon et al., 1996
Synthesis Revised? Nitrogen Export: Results from the Patuxent strongly diverged from other sites not characterized by extensive wetlands (wet) Narragansett Bay Potomac (dry) Patuxent Nixon et al., 1996 Boynton et al. 2008
Synthesis Revised Nitrogen Export: And then aother Chesapeake system diverged, also having extensive wetlands at the land-sea margin (wet) Narragansett Bay Potomac (dry) Patuxent Choptank Nixon et al., 1996 Boynton et al. 2008 Fisher and Cornwell, pers comm
Synthesis Revised Nitrogen Export: And then more systems diverged, all with extensive wetlands (wet) Narragansett Bay Fourleague Bay, LA Potomac (dry) Patuxent Choptank Nixon et al., 1996 Boynton et al. 2008 Fisher and Cornwell, pers comm Justic and Day, pers comm Perez et al (2001); Lane et al (2004)
Synthesis Revised,,, might be something here Nitrogen Export: And then more systems diverged, all with extensive wetlands at the land-sea margin (wet) Narragansett Bay Fourleague Bay, LA Breton Sound, LA Potomac Davis Pd, (dry) LA Patuxent Choptank Nixon et al., 1996 Boynton et al. 2008 Fisher and Cornwell, pers comm Justic and Day, pers comm Perez et al (2001); Lane et al (2004)
Ecosystem Responses to Nutrient Degradation and Remediation Increased algae, hypoxia, turbidity
A “Simple” Response to Nutrient Load Reduction • Waste water treatment plants reduced P-loads P-Loading by >90% in 30 years • Algal blooms and bottom O 2 responded rapidly • Underwater grasses also responded in a favorable fashion Algal Blooms Upper Potomac River and Washington, DC Bottom Oxygen Photo of upper potomac Year (Kemp et al. 2005)
Complex Response to P-Load Reduction P-Load Index ( µ g/l) Potomac River tributary • • Time-series of P-loading index Phosphorus-Load Time-Series includes periods of brief increase and gradual decline Year Phytoplankton Response to P- • Phytoplankton chl-a shows Load Reduction response to P-load reduction Algal Chl-a ( µ g/l) after decade delay, probably due to slow purging of sediment DIP pools (hysteretic Hysteresis? response pattern?) P-Load Index ( µ g/l) • Reductions in phytoplankton chl-a improved water clarity SAV Cover (ha) until a light threshold was reached allowing growth and Threshold? survival of submersed plants SAV Response to Phytoplankton Chris Jones, GMU Chl-a ( µ g/l)
Model of O 2 Interactions with P-Cycle X X X X
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