Chesapeake Quarterly Volume 3 Number 1 · Tall,athletic and highly verbal,Boicourt has some salt in...

CHESAPEAKEQUARTERLYCHESAPEAKEQUARTERLY

Oceanographers on the Bay

MARYLAND SEA GRANT COLLEGE • VOLUME 3, NUMBER 1

E stuaries are perhaps the mostcomplex of coastal systems.The

mixing of streams of fresh and salt-water driven by the flow of riversand tides is then confounded bywind, the passage of storms, and asubmarine topography of deepchannels, sills and the abundantshallows that are so critical to life inthe Chesapeake Bay. Superimposedonto this Bay in motion are thelonger cycles of drought and floodthat in the past few years have hadsuch a profound impact. Our heav-ily populated watershed — ahuman dominated ecosystem —

faces growing urban and suburban development and an evolving agricultural landscapethat continues to contribute nutrients and sediments.These stressors have meant anincrease in the extent and duration of oxygen depletion (anoxia) in Bay waters during2003 — as we go to press, the outlook for the coming summer appears to be similar ifnot worse. To understand what this means, it is important to understand how this Bayworks, or in other words, to understand the context — both physically and biologically— within which human impacts and ecological responses play out.

In this issue of Chesapeake Quarterly, Michael Fincham tells the story of two scientistswhose careers are linked by an academic lineage and a deep commitment to under-standing the physical structure of this estuary. Beginning his work in the Bay in the1940s, Donald Pritchard defined the very fundamentals of how estuarine circulationworks — an accomplishment of great importance both here in Chesapeake Bay and toall estuaries worldwide. His student,William Boicourt, has advanced from this founda-tion to develop a much more detailed picture of the subtle mechanisms and controlpoints that regulate flow and impact biological function. Over the course of two scien-tific generations, these researchers have helped us to understand how the Bay functionson time scales from days, to seasons to years. Equally as important, both have been will-ing and active participants in the process to inform policymakers, managers and thepublic at large — engagement in the best sense of the word.

Jonathan KramerDirectorMaryland Sea Grant

contents3 Betting on Big Science

Oceanographers on the Bay

8 The Hydraulics of a Hot SpotPhysics Affects Bay’s Productivity

10 Underwater WeatherBuoys Serve as Weather Stations

13 Brush Receives MedalPioneering Scientist Recognized

New Science WriterGoldman Joins Maryland Sea Grant

14 Leffler Takes His LeaveTranslator of Science Moves On

Snakeheads Beyond the PondExotic Fish Appears in Potomac

15 Bad Year for Bay GrassesOne-Third Fewer Than Last Year

16 Et CeteraNew Rip Current WebsiteOcean Commission Report

A Bay in Motion

Cover photo: Bill Boicourt, in front of the R.V.Cape Henlopen, before a research cruise.Opposite page: Boicourt and research assis-tant Tom Wazniak lower a ScanFish into thewater where it will undulate through the Bay,measuring temperature, salinity, dissolved oxygen,chlorophyll and plankton. PHOTOGRAPHS BY

MICHAEL W. FINCHAM.

CHESAPEAKE QUARTERLYVolume 3, Number 1 May 2004Chesapeake Quarterly is published four times a yearby the Maryland Sea Grant College for and about themarine research, education and outreach communityaround the state.

This magazine is produced and funded by theMaryland Sea Grant College Program, which receivessupport from the National Oceanic and AtmosphericAdministration and the state of Maryland. ManagingEditor and Art Director, Sandy Rodgers; Contribu-ting Editors, Jack Greer and Michael Fincham. Senditems for the magazine to:

Chesapeake QuarterlyMaryland Sea Grant College4321 Hartwick Road, Suite 300University System of MarylandCollege Park, Maryland 20740301.403.4220, fax 301.403.4255e-mail: [email protected]

For more information about Maryland Sea Grant,visit our web site: www.mdsg.umd.edu

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Volume 3, Number 1 • 3

Betting on Big Science

It will be nearly midnightwhen they finally throw theScanFish off the boat.Standing on the stern of a

research vessel as it pulls slowlyout to sea, Bill Boicourt can see astring of lights receding behindhim.They mark the bridges thatstretch like bright ropes laid acrossthe southern gateway into the Chesapeake Bay. The oceanogra-pher is back out on the ocean again, at least for a little while.

Tall, athletic and highly verbal, Boicourt has some salt in hishair and thirty years of research trips on his resume. He’s out onthe back deck, the working end of the R.V. Cape Henlopen, get-ting ready to launch his favorite research tool — a sleek yellowwing, chopped bluntly at the outer tips and called, logicallyenough, a ScanFish. It’s a high-tech metal and fiberglass fish,crammed with sensing gear, but this fish can’t swim on its own.Boicourt’s plan is to drop the ScanFish out here in the ocean,then tow it back into the estuary and haul it northwards fornearly 200 miles, all the way up through the heart of theChesapeake.

But for now the Henlopen is in a holding pattern, waiting foran incoming ship to clear through one of two deep-water chan-nels, the main runways that big ships use on their approach into

the Chesapeake. Operated by theUniversity of Delaware, theHenlopen is 120 feet long, a goodsize for a coastal research vessel,but a small fish in these waters.

Up on the darkened bridgeCaptain Jimmy Warrington isusing radar and binoculars totrack everything that’s moving

out on this coastal crossroads. Off to the south, he can see ahuge warship riding at anchor, its black mass blotting out theshoreline beyond. Out to the east where the blackness stretchestowards Europe, all he can see of the incoming ship is a dimrunning light. It could be a tanker, bulk carrier or containership, but at this distance, its light is barely visible and barelymoving. Since it’s early April,Warrington also has to watch outfor North Atlantic right whales, big fish that sometimes cruisethese waters.

Out here along the Continental Shelf is where Boicourt didhis thesis work as a graduate student, but he’s spent much of hiscareer working the inside waters of the Chesapeake Bay. He’s aphysical oceanographer, a species of oceanographer that focuseson water masses and their motions.

It’s a branch of science that’s closer to physics than to marinebiology or ecology, but its closest cousin is meteorology.“We are

There is a weather under the Bay, it seems,

and it features some of the same events we

watch on the evening newscast, including

storms, cyclones, high-pressure systems, low-

pressure systems and fronts of all kinds.

BY MICHAEL W. FINCHAM

4 • Chesapeake Quarterly

sort of the meteorologists of the ocean,”says Boicourt, now a professor at theHorn Point Laboratory of the Universityof the Maryland Center for Environmen-tal Science (UMCES). “We are trained alot of times in the same institutions bythe same professors as meteorologists.We’re both dealing with fluids on largescales, what we call geophysical scales.”

Meteorologists deal with the fluids ofair, oceanographers with the fluids ofwater.“There are differences: water isheavier than air,” he says,“but the basicmath and the ways we go about lookingat things are remarkably similar.”

There is a weather under the oceanand the Bay, it seems, and it features someof the same events we watch on theevening newscast, including storms,cyclones, high-pressure systems, low pres-sure systems, and fronts of all kinds, someof them stationary, some mobile, somequite ephemeral. In the Bay there arealso two slow-moving jet streams: riverwater heading south and seawater movingnorth. Just like weather fronts in the sky,these masses of water create structuresand forces in the Bay. They’re not as easyto see as clouds or rain or wind, but theyaffect nearly every life form found in theestuary.

As the incoming ship clears through,Boicourt and the deck crew go to work.A crew member operates the port-sideA-frame, hoisting the ScanFish off thedeck. Grabbing the lift rope, Boicourtstrains backward to keep the device fromswinging too fast out over the side.At300 pounds, the ScanFish is an easy liftfor the A-frame, but if it swings out toofast, it can pendulum back, smashing anoceanographer.

The ScanFish plunks lightly on thewater, then floats quietly — too quietly.“We need to speed it up a little bit,”Boicourt calls out.“It’s caught at the sur-face.” The ship’s technician keeps work-ing the winch controls, paying out cable.As the boat picks up speed, the ScanFishburbles along, then starts a slow dive intodark water.

The ScanFish will be dragged throughthe Bay for the next 30 hours, zigzagging

up and down, its sensors hauling in anocean of data, over 90,000 data points anhour on salinity, dissolved oxygen, chlor-ophyll and plankton. It’s just one of thesophisticated — and expensive — instru-ments that Boicourt and his researchteam have introduced into estuarineoceanography.

In 1989 they created the ChesapeakeBay Observing System (CBOS), a net-work of two to seven buoys that canconstantly measure and instantly commu-nicate data about a suite of water andweather conditions. For those who studythe physics of water masses, the sensors inthe ScanFish and in the moored buoys inthe Observing System have created aquantum leap in high-resolution datagathering.

But it’s an expensive leap.A ScanFish,fully outfitted, costs about $200,000. Aresearch vessel to tow it goes for $7,000a day.A single CBOS buoy, with all itssensors and electronics, can carry a pricetag of $100,000. In terms of dollars perdata point, these devices are a bargain,and they add up to small change com-pared to the costs of deep-ocean technol-ogy. But in the tidal waters of estuarineresearch, this is big dollar science.

Will there be a payoff from thesehuge streams of data that oceanographersare now hauling in? This is the bet ridingon that high-cost technology thatBoicourt just offloaded into the midnightwaters of the Continental Shelf.

Up on the ship’s bridge, the crew hasalready changed shifts.The captain hasbeen relieved by Mike Popovich, theyoung first mate who gets “the dogwatch” from 11:30 until 5:30 a.m. whenthe galley opens for breakfast. Down inthe science lab, Boicourt checks the com-puters monitoring the ScanFish, thenclambers back to his bunk down on thethird level.When he wakes up for hisown 4 a.m. watch, the oceanographerwill be back in the Chesapeake Bay.

The first professional oceanographer towork the Chesapeake arrived here over50 years ago, shortly after World War II,and within a decade made the decisivediscovery that changed the history of sci-ence on the Bay.

First trained as a meteorological cadet,Don Pritchard had been one of a selectgroup of Army soldiers sent to theScripps Oceanographic Institution tolearn new techniques for forecasting seaconditions for amphibious landings.Shortly after D-Day, he landed onOmaha Beach to head the sea swell fore-casting team for the Normandy invasion.

For six months he and his partner,Robert Reid, worked up daily forecastsfor weather, wave conditions and tides,enabling the Allies to keep offloadingtroops, tanks and artillery across thebeaches. Unloading on the beachesworked, enabling the Allies to headinland in force while the Germans kept

ScanFish

One of a new generation of data-gathering tools, ScanFish enables scientists to collect largeamounts of information in a fraction of the time. Before this new technology a typical Bay transectwould take one hour and provide about 30 measurements. The ScanFish, in an undulating tran-sect, can provide measurements of multiple factors every two feet, up to 90,000 an hour.

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thousands of troops tied up waiting todefend the port cities of NorthernFrance. Don Pritchard found himself atthe hinge of history. He was 22 years old.

After the war he returned to Scripps,recruited by Harald Sverdrup, the famousNorwegian oceanographer who was cre-ating the first full-scale graduate programin oceanography in America. Sverdrup’sstudents, some called them “apostles,”would find a hot job market when theyfinished, and they would form the core ofthe first great generation of Americanoceanographers. Even before he com-pleted his Ph.D., Don Pritchard was hiredby Johns Hopkins University to head upa newly created Chesapeake BayInstitute. He was now 27 years old.

His hiring was the result of anunusual agreement among two marinelabs and the United States Navy.WhenReginald Truitt, head of Maryland’sChesapeake Biological Lab, wanted torecruit a scientist to study the Bay’shydrology, he went to the Office of NavalResearch, and he brought with himNelson Marshall, the head of the VirginiaInstitute of Fisheries.They found theNavy eager to maintain America’s newedge in ocean science and willing to putup funds for a new Chesapeake BayInstitute.

The funds came with two conditions:The two state-run labs would have tohelp fund the new facility, but the newInstitute would operate independently ofthem. Truitt and Marshall agreed to anteup $30,000 each, a sizeable sum fromeach lab’s budget, and the Navy matchedthem with another $30,000.That was alot of money in 1949. With $90,000Pritchard would have enough to set up alab, buy some boats, hire scientists andtechnicians, and launch the most ambi-tious research yet attempted on the Bay.

Truitt and Marshall, in turn, had theirown conditions.The new Institute wouldfocus mainly on the physics of the Bay,with some chemistry and geology thrownin. It would not compete with theMaryland and Virginia labs in biology andfisheries science.After all, both directorsran their labs largely with funds directed

at research on the Bay’s highly profitableand heavily harvested commercial fish-eries for oysters, blue crabs and stripedbass.As Pritchard later explained the deal,“The original conception was: youneeded someone working on the wholeBay, not just on the two halves, someonewho would look at how the Bay func-tions, not necessarily the living resourcesin it.”

By putting that much money on thetable,Truitt and Marshall were rolling thedice, making an early big-time bet onoceanography.And on a young war vet-eran who was now expected to producemajor discoveries, plus a payoff for allthose biologists studying oysters and bluecrabs.

Bill Boicourt begins his day on the R.V.Henlopen with a bet of his own, a smallbet about oxygen levels in the Bay.

By the time he scrambles out of hisbunk for his 4:00 a.m. watch, the Hen-lopen has re-entered the Bay, taken a rightturn and headed north, towing the Scan-Fish through the dredged-out deeps ofthe York Spit channel, then through thenatural deeps of the Virginian Sea Trench.

Entering the science lab, he sits downin front of three computer screens, sipson his coffee and checks on the datastreaming up from the ScanFish. “Weought to make a bet, a best guess aboutwhat the oxygen depletion is just belowthe Bay Bridge,” he says to XinshengZhang, the scientist who is going offwatch.“Let’s see who’s right.”

The Bay Bridge, near Annapolis, isstill more than 100 miles north, andnearly 20 hours away, but Boicourt,awake and wired with coffee, is pushingfor predictions.“I want your best guess,Xinsheng.” Down here along the

Virginia Sea Trench, waters at depth arefairly well oxygenated with dissolvedoxygen running around 5 milligrams perliter.That’s a touch low for this time ofyear, Boicourt notes, but still healthy forfish life.Waters falling below 4 mil-ligrams, on the other hand, are labeledhypoxic (for low oxygen). Below 2 mil-ligrams, they are labeled anoxic (for nooxygen) and unable to support life,except for anaerobic bacteria.

Don Pritchard observed levels ofanoxia back in 1949, the first year hetook samples on the Bay. Over the next20 years he compiled a long-term recordthat suggested anoxia and hypoxia wereoccasional but recurring events, especiallyduring late spring and summer. Whenspring rains and runoff bring high inputsof sewage, fertilizer and animal waste, allthese nutrients overfertilize the Bay’swaters, producing blooms of algae andphytoplankton.When those plankton die,they sink to the sediments where theycause another kind of bloom: a popula-tion explosion among bottom-dwellingbacteria.As they feed on and decomposedead plankton, these bacteria suck oxy-gen out of the water.

Pritchard’s oceanographers alsoworked out the physics that helped createthese events.They identified a boundarycalled the pycnocline that can block thenormal mixing of bottom waters withoxygen-rich surface waters.When astrong pycnocline develops, the result isextreme stratification with little or nomixing. Anoxic waters remain capped ina “dead zone” along the bottom. Fish killsand crab kills usually follow.

Boicourt and Zhang aren’t the onlycontemporary scientists watching dis-solved oxygen.Anoxic episodes are nowpublic events, stirring up debates amongscientists and launching news releasesfrom environmentalists. State agencies inMaryland and Virginia track oxygenclosely, considering it one of the keyindicators of general ecosystem health.The Environmental Protection Agency’s(EPA) Chesapeake Bay Program has set aBay-wide average of 5 milligrams perliter as the goal for the restoration effort.

Pritchard compiled a long-term

record that suggested anoxia

and hypoxia were occasional

but recurring events, especially

during late spring and summer.


A numerical modeler working onplankton populations, Zhang finally set-tles on a guess of 4.0 for oxygen at theBay Bridge before heading off for hisbunk. Boicourt’s bet is more precise andless optimistic: He picks 3.43. He’s pre-dicting the waters at the Bay Bridge —even this early in April — will already behypoxic.

The key discoveries came early for DonPritchard. In 1950 and 1951, the youngoceanographer and his new staff motoreddown to the southern Bay in theirresearch vessel, a converted yacht calledthe Joanbar, and mounted a series of now-famous research expeditions along theJames River in Virginia.They broughtwith them a collection of new tools,some adapted from deep-water oceanog-raphy, some created de novo back in theirworkshop.

At station after station, they took cur-rent, temperature and salinity measure-ments at multiple depths.The surfacewater, they found, was river water mov-ing seaward.And down below the freshwater they found seawater sliding in theopposite direction. Colder, saltier, denser,the seawater was flowing up river.

After the measurements came themathematics. From all his data points, sopainstakingly acquired, Pritchard workedout the basic equations of motion thatdescribed the circulation of the JamesRiver, then scaled his equations toexplain the estuarine circulation for theentire Chesapeake Bay. He quickly pub-lished a seminal monograph on “Estua-rine Hydrography” that revolutionizedthinking about the Chesapeake andestuaries around the world.

It was a fundamental paradigm, aturning point for Bay science, accordingto M. Gordon “Reds”Wolman of JohnsHopkins University. “In terms of under-standing how the Bay works,” he said,“Don Pritchard’s physical model wasabsolutely essential.” It changed thinkingabout the Bay more than any other singlepiece of research, according to GeneCronin, the man who followed Reginald

Truitt as a long-time director of theChesapeake Biological Laboratory.

What Pritchard had described accu-rately for the first time was the basic two-layer flow that dominates water move-ment throughout the tidal Chesapeakeand its tributaries. It’s a steady-statemodel, the idealized underlying patternfor a system that never stays stable long.Complicating the interplay between freshwater and salty water are forces likewinds, tides, river discharges, the topogra-phy of the Bay and the rotation of theearth.

Figuring out the physics of all theseforces would keep Pritchard busy fordecades and leave plenty of work for theoceanographers who followed him. Out

of that early model they would derive anassemblage of estuarine features rangingfrom turbidity maxima to plume fronts,upwelling fronts, lee waves, eddies, verti-cal mixing, stratification and anoxiczones.

Betting on Pritchard had paid off, notjust for the state labs that put up themoney, but for all those fishery biologistsstudying the Bay.They could start towork now on figuring out how that two-layer flow was responsible for movingaround and mixing nutrients and plank-ton and early-stage larvae for blue crabsand oysters and finfish.

As first in the field, the youngoceanographer had nailed the essentialphysical feature of nearly all estuaries.

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The pipe smokingDon Pritchard gothis introduction tooceanography workingout sea swell forecastsfor the NormandyInvasion of WorldWar II. The firstoceanographer tostudy the physics ofthe Chesapeake Bay,he discoverd the two-layer flow pattern thatunderles water circu-lation throughout theBay.


And set the paradigm that would keepoceanographers busy in the Chesapeakefor the rest of the century.

As the Henlopen motors north throughthe night, Boicourt stands his watch sit-ting on a stool and eyeballing three sepa-rate computer screens that track theScanFish’s progress up the Bay. Out in theblack water behind the stern, the flyingwing alternately climbs towards the sur-face, then noses over into a steep dive.Water is forced through tubes that caninstantly measure temperature, salinity,oxygen and fluorescence, an indicator foralgae and their oxygen-creating chloro-phyll.The student is getting to play withinstruments his mentor never had.

Boicourt first heard of Don Pritchardwhen he was a senior at Amherst weigh-ing his options.The physics major got acall from the oceanographer asking him ifhe was coming to Johns HopkinsUniversity for graduate school.“I had noidea who he was,” says Boicourt, but heknew Hopkins had great lacrosse teamsand he knew he didn’t want to be a labo-ratory physicist.“I had this image of aphysicist in a white lab coat and glassesand a pocket protector,” he says.“And Ididn’t want to be in a lab.” No place for alacrosse player, better the back deck of aresearch vessel out on the ContinentalShelf at midnight. Oceanographysounded like something that would keephim out of the office.With Pritchard onthe phone, he chose a career.“Okay,” saidBoicourt.“I’ll come.”

Trained in Pritchard’s model of estu-arine dynamics, he soon began exploitingnew field techniques and collecting datathat challenged some of its key concepts.Lucky enough to start graduate workduring an era of steady funding from theNavy, Boicourt worked with a scientificand technical team that was designingand testing new devices for measuringocean flow, including current meters thatcould be moored in place to collectlong-term data. While still a graduatestudent, Boicourt headed up the firstHopkins expedition to try anchoringcurrent meters out on the Continental

Shelf. That experiment deployed meters20 miles out from the mouth of the Bay.Later missions — after a lot of trial anderror and advice — would put buoys 100miles out.

It was Boicourt’s long-term data fromthese off-shore and in-bay current metersthat threatened to disrupt Pritchard’s clas-sic model of estuarine circulation. Insteadof a slow-moving, two-layer flow,Boicourt reported tremendous variabilityin water flows — the result of windpower on water movement. In the coun-try’s largest estuary, there’s plenty of spacefor the wind to crank up, building wavesand shoving water up or down the Bay.Wind motions and tidal surges can nearly

bury any signal of an underlying pattern.“Here I come with long-term currentmeasurements,” says Boicourt,“And sureenough I can’t see the steady two-layerflow very easily because of all this wildwind motion.”

The wind effect was clear to anyonewho saw Hurricane Isabel push Baywaters far up the streets of Annapolis andBaltimore last year. It was clear toPritchard also. From his surf forecastingwork on the beaches of the NormandyInvasion, he knew that wind could movewater quickly, but the mentor never hadthe tools or the long-term measurementsthat his students later had.

Out of Boicourt’s pioneering work,

The Chesapeake is knownas a shallow estuary(average depth 18 feet), butthere are valleys and ridgesand plateaus running alongits bottom. The bathymetryof the Bay plays a big role,not only in ship navigation,but in circulation patternsthat affect food chains, fishmigrations and levels of dis-solved oxygen.

The Deep Trench (90 to160 feet) stretches from theBay Bridge south throughthe mainstem. It followsthe paleochannel for theSusquehanna River that ranthrough here during the lastIce Age. The Trench ends inan abrupt rise at theRappahannock Shoals (38 to44 feet), creating aHydraulic Control Pointwhere south-flowing surfacewater has to squeeze pastsalty, north-flowing bottomwater.

Below the Shoals, the bot-tom drops again, but not asdeeply, into the VirginianSea, a wide swath of waterthat includes a trench nearly70 feet deep and a holenearly 150 feet deep. MAP SOURCE: EPA REGION III.

The Geography Below the Bay

Virginian Sea

MainstemDeepTrench

RappahannockShoals

Hydraulic Control Point


both offshore and in the Bay, came awhole line of research on the way windcan alter the estuarine circulation pattern.It’s a classic example of how science oftenprogresses: from mentor to student, fromsimple to complex.A paradigm is estab-lished, then challenged. New data fromnew tools gradually expand and compli-cate and occasionally replace the oldmodel.

At the Chesapeake Bay Institute onegroup of oceanographers was constantlychallenging Pritchard, sometimes to hisannoyance, pointing to their new data onwinds and currents and the forcing func-tions of distant water.“It is just natural ofyoung people to say: ‘Oh, this is wrong, Iwant to throw over the paradigm,’ ” saysBoicourt.

For the “Young Turks,” as Boicourtcalls them, it was a case, perhaps, of para-digm envy. Pritchard had been first in thefield — he had “the open slate,” asBoicourt puts it — and no amount ofnew data could overturn or erase hisbasic discovery.“Has there been as funda-mental a change in our understanding ofestuaries since Pritchard’s two-layerflow?” asks Boicourt before answering hisown question:“No.That is a fundamentalprocess.And we still have trouble work-ing out all the physics about it.”

The end result was paradigm enrich-ment.A second generation of oceanogra-phers began building models to accountfor wind forces and other sources of vari-ability in Pritchard’s basic two-layer flow.“It is not totally fair to describe what wedo as a mop-up operation,” says Boi-court.“But in some sense it has been —scientifically.”

Pritchard, late in his life, often admit-ted that his discoveries came from beingfirst in the Bay, but he also said he wouldlike to start over with the tools that wereavailable now.The mentor, it seems, wascapable of instrument envy.

And with good reason: devices likethe ScanFish and the Chesapeake BayObserving System would lead to discov-eries barely dreamt of in his paradigm.

One of those discoveries lies justnorth of the Rappahannock River where

The Hydraulics of a Hot Spot

The Hydraulic ControlPoint is a kind of sluice

gate in the middle of theBay that regulates the flowof incoming ocean water.Its discovery came as asurprise, especially for BillBoicourt, and illustratesthe interplay between twokinds of oceanographers:ocean (or Bay) observersand mathematicalmodelers.

As a physical oceanog-rapher, Boicourt is primarily an observational-ist, specializing in testing and developing data-gathering equipment and working out tech-niques for deploying them out on the water.He knew there were structural features likeHydraulic Control Points in the fjords of Nor-way where glacial moraines form high sills,separating seawater from fresh water. He alsoknew nobody had ever found one in the mid-dle of a par tially mixed estuary like theChesapeake.

This new discovery began with the work ofShenn-Yu Chao, a numerical oceanographerwho tests and develops mathematical models,working with the kind of data that Boicour tand other field workers have collected overthe years.While developing a general modelof hydraulic controls in estuar ies, Chao lookedat old data left over from Tropical StormAgnes, a major flood event that hit the Bay in1972. In the old data he saw a rapid decline insaltwater coming up the Bay during and afterthe runoff flooding. He suggested a HydraulicControl was active in the Chesapeake.

The location, according to his analysis,should be right at the juncture where theDeep Trench meets the Rappahannock Shoals.The Trench is the old paleochannel that r unsstraight down the mainstem, stopping abruptlyat the Shoals, a wide band of built-up bottomsouth of the Potomac River.This coupling of aridge with a drop-off creates a sill similar tothose in the fjords of Norway.

Chao works down the hall from Boicour tat the Horn Point Laboratory of the Univer-sity of Maryland Center for EnvironmentalScience, but that didn’t make it any easier for aboat-deck researcher like Boicourt to believea numerical modeler. “This is embarrassing.I sure didn’t see it,” he admits. But the ScanFishdid, sucking up data points by the billions ona series of tows that crisscrossed the Shoalsand Trench in 1999 and 2000. “Lucky wehad the ScanFish,” he says, “because you needthe resolution there to pick this up .” If he hadmade a bet about these f indings, Boicourtwould have lost — and lost big. “It turnsout,” he says, “the Hydraulic Control is muchmore important than even he (Chao)thought.”

Here’s roughly how theHydraulic Control works.Incoming ocean water,dense and cold and salty,surges slowly north alongthe bottom of the Baywhile outgoing river water,light and warm and fresh,slides south along the sur-face. Separating them is aboundary called the pycno-cline. Ocean and river waterboth move with a net aver-age speed of around six

miles a day. Twice daily their progress speedsup and slows down with the tidal cycle .

That’s the steady-state model of estuar inecirculation, according to the physicists, butsteady states never last for long on the Bay. Atthe Shoals, these two streams suddenly haveto squeeze through a narrow slot or sluicegate. Under unsteady states — say heavywinds or river runoffs — all kinds of collisionsoccur. And the physics gets complicated.

Consider scenarios like spring runoff, windstorms or tropical storms: Strong flows ofoutgoing river water rush down the main-stem, overwhelming ocean water at theShoals and pushing down on the pycnocline.The result is like turning a valve: ocean wateris slowed to a tr ickle, robbing the upper Bayof saltwater and zooplankton, fish larvae andoxygen.

The valve can be turned on, often fairlysuddenly. Wind patterns will blow surfacewater away from the sill, lifting the pycnocline,releasing all that backed-up bottom water,unleashing unseen waterfalls well below thesurface of the Bay. Ocean water will comeflooding over the sill and down into the DeepTrench. A batch of high salinity water will f erryplankton and fish larvae and oxygen into theupper Bay. “You’ll sometimes get two weeks ofstrong pulsing flow,” says Boicourt. “And thenit’ll shut down again.”

Along the Hydraulic Control, physicsamplifies biology. Water masses are dr ivingagainst each other, creating density fronts anddownwellings that collect nutrients and plank-ton and fish larvae. These convergence zonescan become biological “hot spots.”

Hot spots like this are now the corner-stone for a new hypothesis about the per sist-ent productivity of the Chesapeake Bay. Theresearch question: Why such an abundance?“You get more fish than you would predict,given the amount of plant production,”explains Mike Roman, a zooplankton ecologistand Director of the Horn Point Laboratory.The proposed explanation: Because thephysics of the system creates so man y front-like features that collect algae and planktonand fish larvae, setting up “chow lines” for for-aging fish at key sites around the Bay.

Why is the Bay soproductive? A newhypothesis about

the physics ofunderwater systems may help answer

this question.

a great hump of sand sprawls across thebottom of Virginia’s Bay, blocking deep-water passage northwards.

Shortly after 5:00 a.m., with theHenlopen at the upper edge of theVirginian Sea Trench, First MatePopovich turns sharply northwest, steer-ing into a dredged-out shipping channelthat slices straight as a drainage ditchthrough an uprising shallows known asthe Rappahannock Shoals.

By now there’s a pale light leakingonto the bridge. Meteorologists call itNautical Twilight, the whisper of lightthat precedes pre-dawn light. Down inthe science lab, Boicourt can glimpse itthrough a porthole, in between checkingthe data stream coming up from theScanFish.To an oceanographer theseRappahannock Shoals are more than aspeed bump on the shipping route toBaltimore.They can affect the physicsof water masses, much like the RockyMountains can affect the physics ofair masses heading east across thecontinent.

It’s well past dawn when the Henlopenapproaches the northern edge of theRappahannock Shoals, but Boicourt isstill inside. Standing in front of two flatpanels mounted high on the cabin wall,he checks the ship’s course and speedacross the bottom, then points down at aspread-out nautical chart.“We’re comingup to a big drop off,” he says, walkingover to the winch control to play outmore cable. He’s going to send theScanFish down into one of the deepestnatural troughs in the Bay.

Here where the Shoals end, the DeepTrench begins. Stretching north towardsAnnapolis, it’s the paleochannel for the oldSusquehanna River that ran through hereduring the last Ice Age. From averagedepths of 40 to 45 feet over the Shoals,the Bay suddenly plunges into a Trenchwith depths of 100 to 160 feet.At thisjunction of Shoals and Trench, oceanogra-phers have discovered a turbulent andunexpected feature of the Bay’s bathyme-try. It’s called the Hydraulic ControlPoint. Created by the physics of wind and


These chow lines, says Roman, are some-times visible. A foam line marks the bound-ary where water masses collide . Fish comeschooling in to feed on plankton. Birds comewheeling over to dive on the fish. Fishermenin boats arrive soon after.

Scientists have also been accumulatingalong these hot spots. Oceanographers andbiologists and plankton ecologists teamed upfor numerous sampling runs as par t of a long-term study called TIES, their acronym forTrophic Interactions in Estuarine Systems.With funding from the National ScienceFoundation, scientists at the Horn Point Labo-ratory worked together with colleagues fromthe Chesapeake Biological Laboratory, theUniversity of Delaware, Old Dominion Uni-versity and NOAA’s Great Lakes Environ-mental Research Laboratory. On two dozencruises, they crisscrossed these chow lines ina sampling frenzy, deploying a number of newtools like the ScanFish as well as old tools likeplankton nets and fish trawls.

All this fieldwork dredged up abundant dataabout all levels of the food web — andprovocative evidence for the productivityhypothesis.“In one trip with the ScanFish, I col-lected more data than I had in 20 y ears,” saysRoman, and when he looked at it a clear pat-tern leaped out. “We analyzed six years of

data,” he says,“and some areas light up everysingle time.There are regular [hot] spots ofhigher zooplankton — and the f ish haveevolved to swim and f ind them out.”

Now that science has evolved to findthese hot spots, the productivity of the Bayis turning out to be quite “patchy.” Twentypercent of the Bay’s waters, Romanestimates, may hold 36 percent of thezooplankton.

Where are these hot patches? Nor th ofthe Chesapeake Bay Bridge — way north in adry year — is the Estuar ine Turbidity Maxi-mum, a mixing zone where the front of thesalt wedge meets freshwater r iver flow fromthe Susquehanna.Wherever a major r iverempties into the mainstem, rich river plumesare formed. Below Smith Point, south of thePotomac, is the on-again, off-again HydraulicControl Point. Down near the mouth of theBay, is the Cyclonic Eddy, just inside the south-ern end of the Eastern Shore peninsula.

You can’t find these patches on boatingcharts of the Bay, not yet.They are not asstriking or evocative as the Bay’s famousbridges and lighthouses and coves and creeks.But they are star ting to show up on mostresearch maps, famous now as the key placeswhere the Bay’s unique physics drives itsbountiful biology.

The Hydraulic Control Point in one of its phases .The Rappahannock Shoals create a narrow sluicegate where two streams of water try to squeeze past each other. In this example, south-flowing surfacewater rubs up against salty , north-flowing ocean water, creating density fronts that collect nutr ients,algae, plankton and fish larvae.These convergence zones can turn into biological “hot spots” where food,prey and predator are all crowded together in small, productive ecosystems.The collision of salt andfresh can also split off a str eam of surface water (as shown above), driving it down to mid-level andcausing a reverse flow that carries warm, well-oxygenated water back up the Bay.

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water and friction, it plays a major role inthe biology of the upper Bay.

At the Shoals, two streams of Baywater — each heading in an oppositedirection — have to squeeze through onenarrow slot. As ocean water, cold andsalty, surges north along the bottom, it hasto push gradually over a wide, uprisingridge. River water flowing south, on theother hand, is running through the longDeep Trench. It faces a steeper rise andsharper funneling.

Collisions can occur — caused bywinds or rain or runoff or a dozen otherscenarios. Stronger flows of south-run-ning river water can pile up at the north-ern edge of the Shoals, creating a tightsqueeze for incoming ocean water. Riverwater can occasionally push down on thepycnocline to the point where oceanwater is literally cut off at the pass. Thephysics of these collisions control thehydraulics of the upper Bay.

Think of a sluice gate, says Boicourt,or an internal valve that can slow downthe flow of deep ocean water into theupper Bay for weeks on end. Oceanwater, of course, comes in bearing giftslike plankton, fish larvae and crab larvaeand an abundance of oxygen.When thevalve is shut, all this rich, salty waterbacks up behind the shoals, starving theupper Bay.

The same forces that shut the valve— the physics of wind and water andtopography — can suddenly turn thespigot back on again.Wind can changethis structure fairly suddenly, holdingback the surface water, releasing the pyc-nocline upwards — and opening thevalve at the Hydraulic Control Point.

The result is a chain reaction — start-ing with an unseen waterfall unleashedbelow the surface of the Bay.“This blastof high salinity water will go over thesefalls, these internal falls, into the deep partof the Bay,” explains Boicourt.“Thatchange, that transition, has a profoundinfluence on the exchange of salt and fishand phytoplankton and nutrients.” Aburst of high salinity water will slidenorthwards at a speed of 10 miles a day,carrying plankton and fish larvae and

Predicting Underwater Weather

There’s a weather under the Bay, complete withhigh-pressure systems, low-pressure systems, sev-

eral kinds of fronts and two kinds of slow-moving jetstreams. Think of physical oceanographers as meteo-rologists of this underwater world. As they figure outthe physics that controls the system, they should beable to predict the underwater weather more accu-rately — and take a lot of guesswork out of the fore-casting game that so many people have to play.

Those were the selling points when ChesapeakeBay Observing System (CBOS) began — betterphysics and better forecasting. Over the last 15 years,Bill Boicourt has kept the system running despite hur-ricanes, lightning strikes, icy winters, vandalism and up-and-down funding cycles. Funding so far has comefrom more than three dozen sources.That’s a lot ofgrant writing, but it has allowed Boicourt to keep buy-ing new buoys, rebuilding old ones and restockingthem with the latest in advanced sensing gear . In yearsof good funding he’s had seven buoys taking datasimultaneously.

Physics and forecasting, according to Boicour t, arestill the selling points for CBOS-like systems expandedto cover the entire Bay and the Mid-Atlantic coastalwaters. CBOS may soon morph into a newer, largernetwork of buoys and land-relay towers, capable ofrelaying even more real-time data about the w eatherabove and below the Bay.The results could boostChesapeake Bay science and help protect the Mar y-land economy.

If the future arrives according to Boicour t’s forecast,CBOS could evolve into a cooperative regional systemwith more stable funding and more par tners fromacademe, state and federal government, and privatecorporations. Players could include the Virginia Instituteof Marine Science (VIMS), Old Dominion University,the Environmental Protection Agency, NOAA’sNational Ocean Service, the U.S. Navy, the U.S. CoastGuard, the Alliance for Coastal Technologies, and stateagencies in Maryland and Virginia.The result would bea cooperative system, perhaps with a new name , thatwould provide real-time weather and water data fromthe head of the Bay all the way out onto the Conti-nental Shelf.

There are even larger plans afloat. Congress is now considering a proposal for funding andexpanding systems like CBOS and linking them together into a lar ger coastal network.That couldmean more money and more acronyms. CBOS might be renamed and linked into somethingcalled IOOS (Integrated Ocean Observing System) or C-GOOS (Coastal Global Ocean Obser v-ing Systems), both of which would be par t of an overall system called GOOS. Those plans drew amajor endorsement last week in the Preliminar y Report of the U.S. Commission on Ocean Policy.

The science prize is long-term data that oceanographers can use for figuring out the physics ofthe Bay and other coastal systems in greater detail. Better forecasts are also in those details, espe-cially details about water temper atures, winds on the Bay, waves and currents that result fromthose winds.

The practical prizes are real-time products forecasting what the system is doing toda y andtomorrow.That’s important for big commercial shipper s who need to know water levels up in Bal-timore Harbor and small recreational boater s who want to know wave conditions out on themainstem. Real-time models of current flows would help with search-and-rescue missions and withemergency responses to natural disasters like storm surges and human accidents like oil spills andchemical leaks. CBOS can even help with Homeland Secur ity with high-frequency radar that helpstrack large and small ships as they mo ve about the Bay.

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Like a band of robots, CBOS buoysstand watch over the Bay. Some stay onstation year after year, like the one off theChoptank River. Others come and go,moved to monitor a par ticular area, orpulled for fear of ice. Shown on the mapare a string of buoys, some on stationand some still proposed, waiting for theregion’s next investment in remotesensing.

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oxygen.Water masses colliding here at theControl Point can also create oddities likeinternal underwater waves and a three-level flow pattern caused by surfacewater diving beneath incoming oceanwaters.

All this action at the HydraulicControl Point tends to collect algae andplankton and larvae near the surface,turning this turbulent zone into one ofthe Bay’s biological “hot spots.”Whereverwater masses bump into each other, con-vergence zones are formed, gatheringfood and creating “chow lines” for fish,according to Mike Roman, a planktonecologist and the director of the UMCESHorn Point Laboratory.

There are other recurring hot spots atthe head of the Bay, down at the mouthand at numerous sites along the mainstem.At the north end is the Estuarine TurbidityMaximum (ETM), a mixing zone wherethe leading edge of the salt front meetsfresh water flowing down from theSusquehanna.A moveable feast, the ETMshifts its position depending on river flow,sliding up Bay in dry years and down Bayin wet years.At the south end of theChesapeake, there appears to be aCyclonic Eddy, according to predictionsby Raleigh Hood, a modeler at HornPoint.As water flows around the bottomcorner of the Eastern Shore peninsula, itseems to create a slowly swirling eddy.Andfinally, where large rivers meet the Bay,rich plume fronts are created.All these fea-tures are natural traps for algae and plank-ton making them natural targets for fish.

Hot spots are at the center of a newhypothesis about a couple of perennialpuzzles:Why do estuaries, in general,hold more fish per acre than oceans? Andwhy does the Chesapeake still hold morefish than other estuaries. Perhaps becausethe physics of the system creates so manyfront-like features that collect algae andplankton and fish larvae, setting banquettables around the Bay for foraging fish.

Now that the physicists of the Bay areable to find these fronts, biologists areexpanding some of their old paradigmsfor explaining the rich productivity ofthe Bay.

Not a bad payoff for the high-dollarbet that, 50 years after Pritchard’s firstwork, there is still a lot to learn about thephysics of the estuary.

None of the learning comes easy, noteven with high-tech gear, not whenyou’re working on the water.

Shortly before sunset, near the end ofBoicourt’s afternoon watch, the ScanFishsuddenly goes wildly off track, swingingcrookedly at the end of its cable like ahorse that’s thrown its jockey.

Scientist and crew winch the ScanFishup onto the back deck of the Henlopen,and the guessing game begins. Boicourtand Bryan Kidd, the technology guru forthe boat, spend 40 minutes down ontheir knees on the darkening deck, prob-ing the innards of the left-side panel withscrew drivers and needle-nose pliersbefore they find the problem. One tiny,10-cent screw had slipped out of placeand disappeared into the Deep Trench.

The ScanFish is back in the watershortly after dark. By 11:00 p.m. it is tak-ing deep trough samples as it passes underthe Bay Bridge, and it’s clear thatBoicourt has won his bet on dissolvedoxygen.The waters below the Bay Bridgeare already hypoxic in early April — justas he’d guessed.That’s bad news for theBay.“It’s going to be a big year, I think,for anoxia,” says Boicourt.

The last job for this cruise of theHenlopen is to pull up a big, expensive,and badly damaged buoy that spent thewinter locked in the ice out on theChoptank River.

For three years, it had been takingmeasurements on weather and waterconditions and relaying real-time databack to the Horn Point Laboratory.Thenin January, the buoy went dead.

As the Henlopen glides up to the float-ing yellow tower on a gray morning inApril, Boicourt can see why:The super-structure is banged up, the radio antennais busted, and the solar panels are shat-tered.That’s just the damage above thewater line.This is what the ancientphysics of ice can do to the latest tech-nology for science.

The big buoy is one part of theChesapeake Bay Observing System, anetwork of data-gathering buoys andland-relay stations that Boicourt first pio-neered back in 1989. He began CBOS,as it’s called, with two buoys, but in yearswhen the funding was there Boicourthas had seven buoys out on the Baysimultaneously.

Every winter Boicourt has to facesome tricky gambles with CBOS. Willthe Bay ice up around his buoys? If so,which ones should he take out.“In thenorthern Bay, up near the SusquehannaRiver, the salinities are low, so it alwaysfreezes up there,” says Boicourt.“Wealways take that out.” But he gambles alot with the mid-Bay buoy and usuallywins.The Choptank River was supposedto be a safe bet.

For the buoy pickup, the entireHenlopen crew minus the cook turns outin hard hats and life vests. Hoisting atwo-ton tower on board a crowded deckis awkward, even dangerous work, withan engineer running the crane and every-body else pushing with poles or pullingwith ropes, trying to keep the fat-bot-tomed buoy from smashing the boat orthe crew.

As they slowly swing the buoy ondeck, Boicourt can see the rest of the badnews.The ice field cut ugly brown gashesin the yellow foam protecting the hull. Itknocked the tower on its side, breakingall the weather sensors, pulling the datacable out and opening a hole in the side.After the ice damage, waves kept slappingthrough the hole, slowly flooding theelectronics package buried in the hull.“We lost at least $30 to $40 thousanddollars worth of gear here,” he says,pointing to the water now draining outof the hull.

It’s one of the costs of doing scienceat sea, according to Boicourt. Oceanogra-phers have been losing meters and buoysto the Bay ever since Don Pritchardstarted work in 1949. Systems like CBOSand ScanFish represent elegant technicaladvances in data gathering, but they stillfall victim to 10-cent screws that disap-pear into the Deep Trench, lightning



strikes that knock outtelemetry towers and win-ter weather that ices overthe Chesapeake.

Along with the mishapshave come the payoffs: bet-ter forecasts for shipping onthe Bay and deeper insightsin to the physics of the sys-tem. But these kinds of sys-tems — and these kinds ofpayoffs — are only builtthrough years of trials anderrors and ice damage.“We’ve had these disastersbefore,” says Boicourt, ”andwe will again in thefuture.”

The future may holdmore trials for Boicourt,not only in the Bay, but back out on theContinental Shelf where he began hisresearch career. Since the physics of theBay’s circulation is driven, in part, by thephysics of ocean circulation, he hopes toplant one of his CBOS buoys outside themouth of the Bay so he can track thecondition of incoming ocean water.

That incoming Shelf water may, inturn, be driven by forces let loose hun-dreds of miles away. Consider the GulfStream, one of Boicourt’s favorite exam-ples.As it curves east of Canada, it canspin off an eddy of cold water 100 mileswide that starts cruising south throughthe deep water next to the ContinentalShelf. “On the way down, it’s bangingagainst the Continental Shelf,” saysBoicourt,“injecting high-salt water andorganisms into the Shelf waters, condi-tioning the whole water that theChesapeake Bay talks to.”

As those Shelf waters then surge in atthe southern end of the Bay, they carryremnants of that eddy — temperature,salinity and density conditions that willdrive the physics of the Bay system all theway to Baltimore and beyond. Half thewater in the Bay is ocean water. Saltywater off Annapolis is shaped, in part, byseawater off Nova Scotia.

If that eddy from up north sounds alot like the butterfly effect from Chaos

Theory, remember that it was a meteor-ologist, Edward Lorenz, who first stum-bled upon Chaos Theory.A single butter-fly flapping its wings produces a tinychange in the atmosphere. Months later,on the other side of an ocean, a hurri-cane that wasn’t going to happen hitsland. Or one that was going to happennever forms.

Meteorologists try to overcome theanarchy of nature by bringing moreweather stations on line and buildingmore sophisticated mathematical models.Oceanographers, their first cousins, aretrying the same tack.“We are all sittingthere saying, why don’t our modelswork?” says Boicourt.“Well, we have toinclude that long-range influence, andthat is one of the reasons that we have tohave large, nested observing systems.”

That means more than an expandedCBOS.Wending its way throughCongress is a proposal for a networklinking a number of existing coastalobserving systems along the Atlanticseaboard. Chesapeake Bay modelerswould be working with data from theGulf of Maine, from Cape Cod, LongIsland Sound, the Jersey coast and someof the coastal states to the south.Thesesystems would be nested, in turn, in aneven more ambitious, and expensive,Global Ocean Observing System.

Boicourt thinks theinvestment will pay off.Billions of data points,faster computers, moreagile mathematical models— what do they add upto? What would CBOS dowith data on distant waters.“With advanced tech-niques and advanced com-puter power,” saysBoicourt,“we can nowwrite numerical modelsthat are very accurate andvery resolved.”

The up side of ChaosTheory is better (but notperfect) predictability and abetter understanding of theBig Picture. Meteorologists

can give pretty good 24-hour forecastsfor the Bay weather, and they can con-nect them to forces like the NorthAtlantic Oscillation, El Niño in thePacific or Global Warming around theplanet.

Oceanographers think they can dothe same thing for the underwaterweather of the Chesapeake Bay.The eddyfrom up north would still come this way,but they would know when it’s comingand what kind of water it’s carrying.Theycould also work out forecasts about whathappens when remnants of the eddy tryto cross the Rappahannock Shoals andstart cruising up the Deep Trench towardsBaltimore. Numerical oceanographers, ofcourse, would have to put all that datatogether in their mathematical models.

Walking around the work deck of theHenlopen, Boicourt, the boat-deck scien-tist, is already putting his banged-up buoyback together in his head.“We’ll have toreplace the hull.We’ll sandblast all themetal parts, replace the electronics.” hesays.”We’ll need new solar panels.”Thetower, at least, is still usable.And theoceanographer is still optimistic.“We’llget it back in shape.”

If the country is ready to place anotherbet on big science, Bill Boicourt will beready to take his buoys back out on theocean.

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A weather buoy comes aboard after a bad winter in the Chesapeake Bay. Icefields cut and battered the hull and caused flooding that destroyed the electronicspackage carried inside.


Brush Receives Mathias MedalGrace Brush, a scientist well known

for her work on the pre-Colonialecology of the Chesapeake Bay, has wonthe prestigious Mathias Medal in recog-nition of scientific excellence. WilliamR. Brody, President of the Johns HopkinsUniversity, presented the award to Brushon May 6, 2004 at a well-attended cere-mony in Washington, D.C.

Named for former Maryland SenatorCharles “Mac” Mathias — who is widelycredited with launching a federal-statepartnership to restore the Bay — theMathias Medal recognizes scientistswhose work has had a significant impacton policies affecting the Chesapeake.Awarded by the Sea Grant programs ofMaryland and Virginia and theChesapeake Research Consortium, theMedal has been given only four timessince its creation in 1990.

A professor in the Whiting School ofEngineering, Department of Geographyand Environmental Engineering at theJohns Hopkins University, Brush is thefirst paleoecologist to win the award.She is also the first woman.

Brush pioneered studies that use thepresence of plant pollen, microscopicorganisms and other substances in Baysediments to track changes in the estuaryand in the watershed that surrounds it.Her studies have provided the basis formuch of our understanding of how andwhen the forests surrounding the Baywere first cleared, and how resultant shiftsin sediment loads and water chemistrychanged the Bay and its ecosystem.“When policymakers attempt to com-pare the Bay of the past with the Bay ofthe future,” says Maryland Sea Grantdirector, Jonathan G. Kramer,“they turnto the work of Grace Brush.” Kramercalls her work “pivotal,” because it hasdetailed the story of the Bay’s response tohuman settlement, beginning with theclearing of the region’s forests and con-tinuing right up to the impacts of sewagetreatment plants.

“Grace Brush hasbeen extremelyhelpful in identi-fying the impactsof land usechanges on theBay,” says AnnSwanson, Execu-tive Director ofthe ChesapeakeBay Commission.“Her work is

very concrete. It’s added to the quiver offacts you need to hit the target [of nutri-ent reduction].”

“There are many scientists workingon the Bay, but only a few who reallyinfluence you,” says Swanson. “GraceBrush is one of those few.”

A new science writer has arrived atMaryland Sea Grant, Erica Goldman.With a Ph.D. in biomechanics fromthe University of Washington, andexperiences both in journalism andmarine policy, Goldman is well suitedto tackle the often complex topicsthat emerge from marine issues in theChesapeake region. Raised right inManhattan, she has developed a keenappreciation for the outdoors andthe marine environment and nowfinds that the big city can be a little“claustrophobic.”

Goldman has worked as a writer atWashington Sea Grant and at Science,the journal of the American Associationfor the Advancement of Science(AAAS), where she focused on report-ing news and synthesizing scientificarticles for the web. She also served asa Knauss Fellow on Capitol Hill, where

Ted Poehler,Vice Provost forResearch at the Johns Hopkins Univer-sity, calls Brush a “cornerstone” of herdepartment. “Grace has a long andimpressive history at Hopkins,” he says.“She helped others and helped to bringstability to that program and to [thestudy of] the Chesapeake Bay.” Poehlerpoints out that Grace has set an impor-tant example for women in science.“Back in 1956, when she got her doctor-ate, the number of women in engineer-ing fields was quite small. The womenwho did enter the sciences were morelikely to enter biology or chemistry.”Researchers like Brush were really “pio-neers,” he says. “It was pretty lonely.”Adds Poehler,“We need more role mod-els like Grace.”

she had anopportunity toobserve first-hand the roleof science inshapingmarine policyon a nationallevel.

Her interests in research and inwriting came together in 1999, whenscience writer David Gordon spoke toher science journalism class. Thoughher graduate work was highly special-ized, says Goldman, she found that shemissed “the breadth of science.”

In her fellowship on Capitol Hillshe took on the role of explaining themarine sciences to a larger audience,where science, policy and public inter-ests meet.“Sea Grant,” she says,“isplaced right at that intersection.”

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Maryland Sea GrantWelcomes New Science Writer

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Leffler Takes His Leave

A fter twenty-three remarkable years of writing aboutand reflecting on science and the Chesapeake Bay,Merrill Leffler retired from his post as writer and edi-

tor for the Maryland Sea Grant College on April 1, 2004.Born in Brooklyn, New York, and raised in North

Carolina, where his family had moved during his preteen years,Leffler graduated from the North Carolina State Universitywith a degree in physics. One of his first jobs was with theNational Aeronautics and Space Administration (NASA),where he became a vehicle manager, in charge of launchingrockets for atmospheric and meteorological research.

Leffler early on found himself drawn to words and litera-ture, however, and as columnist Henry Allen wrote in a Washington Post feature, Lefflerturned away from his aeronautical career to pursue the language and literature that heloved. Leffler went on to graduate school in English literature at the University ofMaryland and then at England’s Oxford University. He taught literature at the Univer-sity of Maryland, the U.S. Naval Academy, and at literary workshops here and abroad.

In addition to his own writing and teaching, Leffler has long encouraged and pro-moted the efforts of others.Through his own company, Dryad Press, he has publishedthe work of numerous poets and writers, with a special emphasis on Holocaust litera-ture. One collection of Israeli poems on war and peace, entitled After the First Rain, car-ries a preface by former Prime Minister Shimon Peres, who spoke fondly of the workat the book’s inaugural reading in Washington, D.C.

For those interested in the Chesapeake Bay, Leffler is best known for his in-deptharticles on marine science and affairs. For many years he has followed scientific studiesof the Bay ecosystem and its fisheries, including the oyster industry — from the resur-gence of parasitic disease in the mid-1980s to heated debates over the introduction ofnon-native oyster species, such as Crassostrea gigas and, currently, Crassostrea ariakensis.

Leffler’s work is informed by deep understanding, the result not only of numerousinterviews with researchers throughout the region and beyond, but also of painstakingreading of scientific journal articles, reports and research notes.At Maryland Sea GrantLeffler found a place where he could join his interest in science and his passion forwriting.“When I saw the advertisement in the Post [in 1981],” Leffler said,“I said, ‘Thisis the job I want.’”

Many would agree that it was a happy confluence.With issues facing the Chesa-peake growing increasingly complex, and with many clamoring for over-simplifiedsolutions, Leffler’s careful and balanced analysis of issues such as oyster aquaculture, fish-eries management and contaminants in the Chesapeake helped to provide measured andsophisticated background and up-to-date information for a broad, interested audience.He also helped to explain the Bay’s intricate physical and biological dynamics, the forcesthat drive its rich food webs and fabled productivity.

Leffler may be retiring from the nine-to-five life, but he’ll be just as busy. This sum-mer he will present lectures on culture, literature and sense of place in Great Britain,and then will return to the things he loves most — his family, including two younggranddaughters, and his literary work.A farewell gathering held at the end of March inCollege Park served as testimony to the community’s fondness and regard for him.“When I came to Sea Grant I found people who care about the same things I do,” hesaid. He also found a community of scholars and others who came to appreciate hisunflagging curiosity, intelligence and warmth.

Snakeheads GoBeyond the Pond

When the first of the northern snake-heads, the Asian exotic fish that canbreathe air and survive for short periodson land, was plucked from a Crofton,Maryland pond in the summer of 2002,it catapulted onto David Letterman’s TopTen list and grabbed the nation’s collec-tive consciousness. Now the infamousfish is back in the Chesapeake region andit could be settling in to stay.

Troubles began again on April 26,when an angler snared a 19-inch, femalesnakehead from a pond in Wheaton,Maryland. Over the next week, theMaryland Department of NaturalResources (DNR) drained the pond butdid not find other fish.

Any sigh of relief was short-lived,however, and the following weeks havebrought further cause for concern. OnMay 7, a fisherman landed an immaturefemale snakehead from Little HuntingCreek, a tributary of the Potomac Riverin Virginia. Later in the week, anotherangler pulled up another female on thenearby Maryland side of the Potomac, inCharles County. And a few days afterthat, a participant in a bass fishing compe-tition snagged a third snakehead, of a sim-ilar size, from a site along the Potomacabout 10 miles downstream from LittleHunting Creek. Maryland DNR hasposted emergency snakehead fish warningsigns along the Potomac. The agency isencouraging fisherman who catch themto kill them and to expeditiously reportfindings to the authorities.

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Unlike ponds, which can be drained,the Potomac River is a system of inter-connected waterways that stretches for280 miles. “From a management stand-point, finding the fish in an open body ofwater certainly elevates the level of con-cern,” says Andy Lazur, an aquacultureextension specialist from Maryland SeaGrant Program, who served on theMaryland Snakehead Scientific AdvisoryPanel in 2002.“And if the fish doesbecome established, managers will have to

manage around the fish.And there arelimited tools available,” he says.

But finding a few snakeheads in thePotomac does not mean that a reproduc-ing population has established. “Threefish, a population does not make,” cau-tions Paul Shafland, director of the Non-Native Fish Research Laboratories of theFlorida Fish and Wildlife ConservationCommission in Boca Raton, Florida.“Three fish out of the same and adjacentsystems does certainly raise your eye-

brows, but it is important to confirm theexistence of a population before jumpingto any conclusions,” he says.

Some believe that the evidence isalready fairly compelling, however.“Snakeheads are probably already prettywidespread in the system,” says fisheriesbiologist and snakehead specialist WalterCourtenay from U.S. Geological Survey’sFlorida Integrated Science Center inGainesville.The larger fish caught inWheaton is of a different size and ageclass than the three caught in thePotomac, and these bodies of water canall be linked together geographicallywhich suggests that there might be areproducing population, he says.

But even if the snakehead is here tostay, the effect of a new predator in thefood web will take years to understandand, in the end, may not have a cata-strophic ecological impact.“Freshwaterfish communities are far more plastic andresilient than we would expect,” saysShafland.“An introduction of a freshwaterexotic is more akin to ecovandalism thanecoterrorism,” he says. In addition, otherpredators in the system, such as large-mouthed bass may actually consumesnakeheads.According to Lazur,“There isno way to predict how these fish willrespond as both predator and prey in thesystem. It remains to be seen.”

Whether or not snakeheads live up totheir “Frankenfish” profile in the media,they have become poster children forcommunicating the risks of introducingexotic species to the environment. “Ifthere is one take-home message from thesnakehead introduction,” says Shafland,“itis that it is the public’s responsibility notto release exotic species into the wild. It isillegal and it is inhumane for the animal.We need to take this seriously,” he says.

— Erica Goldman

Northern Snakehead Weblinks

Snakehead profile – http://www.invasivespecies.gov/profiles/snakehead.shtml

Washington Post Webcast with Andy Lazur – http://www.

washingtonpost.com/wp-dyn/articles/A36762-2004May18.html


Bad Year For Bay GrassesSubmergedAquatic Vegeta-tion (SAV) inthe ChesapeakeBay dropped by30 percent from2002 to 2003,according to areport synthesiz-

ing the annual aerial SAV survey datacollected by the Virginia Institute ofMarine Science. Released on May 18 bythe Chesapeake Bay Program, the reportcalls this the largest single-year decline inSAV since 1984.

The marked decline of Bay grasses in2003 is linked to near-record rainfalls dur-ing last spring and summer that washedcolossal amounts of nutrients and sedimentfrom the land into the Bay, according tothe report. Increased water turbidity, whencombined with cloudy, sunlight-poor days,hampered the grasses’ growth.

Bay grasses are critical players in theChesapeake Bay ecosystem. They oxy-genate estuarine waters and provide food,shelter and nursery areas for juvenilestriped bass and crabs. They also act toreduce pollution by absorbing nutrientsand trapping sediments.

Since the 1960s Bay grasses have seena steady decline due to poor water qual-ity and enhanced growth of epiphytes —which foul underwater plants. Scientistsand regional partnerships have been

working hard to reverse the trendthrough directed restoration efforts. Inthe past 15 years, there has been some re-growth of SAV in the Bay, but at least inbrackish areas, recovery has been limitedto one species commonly known as wid-geon grass, explains ecologist MichaelKemp of Horn Point Laboratory.

“Thirty years ago, in this same region,there were six or seven species that werepretty abundant. As a community, it wasmuch more robust. Now the system ismuch more vulnerable to variation in cli-mate — like what occurred in 2003,” hesays.

Kemp is not surprised that a singleyear with extremely high levels of precip-itation caused such a striking decline inSAV. “It’s a reminder that the plants dis-appeared originally because of poor waterquality. And this underlying problem hasnot improved,” he says.

— Erica Goldman

SAV WeblinksChesapeake Bay Program – http://

www.chesapeakebay.net/baygras.htmVirginia Institute of Marine Science –

http://www.vims.edu/bio/sav/Maryland Department of Natural

Resources – http://www.dnr.state.md.us/bay/sav/index.html

NOAA Chesapeake Bay – http://noaa.chesapeakebay.net/sav.htm

US Fish & Wildlife Service Chesapeake Bay Office – http://www.fws.gov/ r5cbfo/CBSAV.HTM

New Rip Current Web SiteSummer is off toa somber start in

southeast this year. In May alone, threedrowning-related deaths in Florida havebeen blamed on rip currents, fast-flowingcells of water that move offshore.To raisebeachgoer awareness, the National Oceanicand Atmospheric Administration (NOAA),in partnership with the United States Life-saving Association and the National SeaGrant College, kicked off a nationwidecampaign on May 24 to communicate criti-cal safety information.

A key component of the campaign is anew website from NOAA’s NationalWeather Service,“Break the Grip of theRip” [http://www.ripcurrents.noaa.gov/index.shtml], that provides real time safetyinformation on surf height and rip currentrisk for eight sites on the Atlantic Ocean,ranging south from New Jersey to Florida,three sites on the Gulf Coast, and three siteson the Pacific Ocean.The site also aims toinform swimmers about rip currents, howto recognize them, and how to survive themsafely if encountered. It emphasizes the

importance of going with the flow and notfighting the current.“Think of it like atreadmill that cannot be turned off, whichyou need to step to the side of,” the siteadvises. The website is complemented by anationally-standardized sign for beach com-munities and a brochure that will be avail-able in both English and Spanish.

Ocean Policy CommissionReleases Preliminary Report

That the oceans are in serious trouble is theclear message of a recently released prelimi-nary report of the U.S. Commission onOcean Policy. Made public on April 20, thereport calls for action to be taken now toreverse serious declines in water quality anda host of problems, including loss of habitatand living marine resources, plaguing U.S.coastal and ocean waters. It recommendsenhancing and radically changingapproaches to cooperation and coordinationat the federal, state and local levels andstresses the need for ecosystem-basedmanagement.

Other major recommendations proposerestructuring U.S. ocean governance, includ-

ing establishing a National Ocean Councilwithin the Executive Office of the Presi-dent, strengthening the National Oceanicand Atmospheric Administration andincreasing spending on marine research andeducation. Overall, the report estimatescosts for reversing declines and restoring thenation’s coasts and oceans at about $4 billionannually, and suggests these funds couldcome from existing offshore oil and gas leas-ing activities that occur within U.S. coastaland shelf waters.

The report has some good news for theChesapeake Bay as it endorses many of thegoals set forth in Chesapeake 2000, the blue-print for Bay management. Regional over-sight and management of coastal watershedsare valuable, according to the report, andcoordinated efforts such as those currentlyworking in the Chesapeake are importantmodels for how U.S. coasts should be man-aged. The Sea Grant College program iscited several times in the report as animportant and successful mechanism forbridging the gap between ocean researchand education, and additional support forthis program is urged.

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