Invasive Species in theChesapeake?Blocking Species

Invasions in the Bay

CHESAPEAKEQUARTERLYCHESAPEAKEQUARTERLY

MARYLAND SEA GRANT COLLEGE • VOLUME 8, NUMBER 2

contents Volume 8, Number 2

Cover photo: Dark sentinel on the Baltimore waterfront, the MV Cape Washington keeps watchafter its return from the war in Iraq. While it waits in ready reserve, the ship serves as a maritimetest facility, helping to defend against invasive species transported in ballast water. PHOTO BY JESSICA

SMITS. Opposite page: While the Potomac may be known as “the nation’s river,” it’s now home toseveral species from far away, including snakehead and hydrilla from Asia. PHOTO OF POTOMAC RIVER BY

MICHAEL W. FINCHAM; INSET PHOTO OF SNAKEHEAD (LEFT) BY THE U.S. GEOLOGICAL SURVEY; INSET OF HYDRILLA

(RIGHT) BY MICHAEL NAYLOR.

CHESAPEAKE QUARTERLY June 2009

Chesapeake Quarterly explores scientific, environmental, and cultural issues relevant to the Chesapeake Bay andits watershed.

This magazine is produced and funded by the Maryland Sea Grant College Program, which receives supportfrom the National Oceanic and Atmospheric Administration and the state of Maryland. Editors, Jack Greer andMichael W. Fincham; Managing Editor and Art Director, Sandy Rodgers; Contributing Editor, Erica Goldman;Science Writer, Jessica Smits. Send items for the magazine to:

Maryland Sea Grant College4321 Hartwick Road, Suite 300University System of MarylandCollege Park, Maryland 20740301.405.7500, fax 301.314.5780e-mail: mdsg@mdsg.umd.eduwww.mdsg.umd.edu

We gratefully acknowledge support for Chesapeake Quarterly from the Chesapeake Bay Trust for 2009.

8 Pathways for InvasionNon-native species follow surprising routes to end up in the Bay and its tributaries.

10 Navigating Ballast Water ManagementBreaking down the complex landscape of state, federal, and international regulations.

12 Killer from across the SeaScientists puzzle over the enduring mystery of MSX, a non-native parasite that’s plagued the Bay’s oysters.

4 A Question of BallastCan we protect the environment from invasive species and make ships safer?

14 Travels with HydrillaThe tale of a monster weed’s journey to our nation’s capital.

Volume 8, Number 2 • 3

T hey called it “the frankenfish.” It was thesummer of 2002, and an invasion by an air-breathing fish from Asia that could walk on

land spurred a media frenzy. Though the most sen-sational stories proved to be nothing but fish tales,the snakehead soon became a poster species forhow easily non-native animals and plants can setup shop in the Chesapeake. No sooner had offi-cials eradicated the toothy invader in a Crofton,Maryland pond than it showed up in the Potomac.The snakehead quickly established what appears tobe a firm finhold in the river.

Less able to grab the headlines are scores ofother non-native species — plants, animals, andmicrobes introduced from somewhere else andnow in the Bay. Some of these species have takenhold without notice and without apparent harm.Others have killed our oysters, smothered ourgrasses, degraded our shorelines.

And there are thousands of other non-nativespecies that could yet come to the Chesa peake.That’s according to experts like Greg Ruiz, head of the MarineInvasions Research Laboratory at the SmithsonianEnvironmental Research Center. We don’t know which specieswill come and when, where they will end up, or whether theywill cause real harm. It’s a numbers game, says Ruiz. An ecologi-cal roulette of sorts.

What do we do when we lose the game — when anunwanted species shows up on our doorstep? This past yearMaryland Sea Grant helped draft a plan for the Mid-Atlanticstates to use when faced with an unintended introduction of anon-native species. The plan outlines necessary steps for a “rapidresponse” — from deciding whether to take action, to determin-ing control methods, to monitoring results.

The idea was to keep the plan short and simple. It still turnedout to be over 40 pages. The plan’s unexpected length speaks tothe complexity of controlling an invasive species once it’sarrived. An effective response effort is, unfortunately, seldomshort. Or simple.

While working on the plan, I kept thinking about BenFranklin’s well-worn adage, “An ounce of prevention is worth apound of cure.” Though it’s important to respond rapidly to aspecies invasion, the better goal is to avoid that situation in thefirst place.

This is where understanding pathways for invasions becomescritical — what scientists call vector ecology. Whether by com-

mercial cargo ship or a weekend warrior’s Boston Whaler, baitbuckets or fly-fishing gear, how we spread invasive species maybe just as important as what we do once they get here.

The Maryland Department of Natural Resources convened ameeting over the winter to discuss the discovery of several zebramussels near the lower portion of the Susquehanna River. Oneattendee lamented that the public might grow weary of hearingabout another “new” invasive species. Snakeheads. Mitten crabs.Now zebra mussels. Another biologist responded that this marchof new invaders shows that focusing on pathways rather thanindividual species is key. One set of preventive measures —properly cleaning boat hulls, for example — could avoid theintroduction of a whole host of organisms.

In this issue of Chesapeake Quarterly we explore pathways thatinvasive species can take to get here, from commercial shippingto the actions of everyday citizens.

We also tell the stories of two non-native species, one that’shad devastating consequences for the Chesapeake, and one thathasn’t lived up to its initial threat.

Some argue that the introduction of non-native species is anatural turn of events. Plants and animals have been coming andgoing for millennia. Why should we try to stop them?

The short answer may be, it’s a numbers game. Is it worth thegamble?

— Jessica Smits

The Ecological Numbers Game

T he wind kicks up over BaltimoreHarbor and sends a hard hat flyingalong the dock. March is going

out more lion than lamb. From behind agritty industrial building come three U.S.Coast Guard inspectors striding along inmatching navy-blue jumpsuits. They walkwith authority to a black-and-white cargoship docked in the Patapsco River alongthe Domino Sugar pier. The ship hascome to the refinery to deliver 15,000metric tons of Mexican sugar. The CoastGuard has come unannounced.

The inspectors walk along the dockchecking the condition of the twenty-twoyear-old ship. Block letters painted whiteon the black bow spell out its name andorigin: Tamoyo Maiden. Manila. One offi-

cer lifts a tarp on the side of the ship toeyeball the hull’s level in the water. It’s allpart of a Port State Control Inspection tosee whether a foreign ship is complyingwith United States and international mar-itime laws on safety, security — and theenvironment.

A bakery-sweet smell spices the air asthe inspectors climb to the main deck, thebright orange steps sticky under theirblack steel-toed boots. At the top, mem-bers of the Tamoyo’s Filipino crew checktheir identification, then quickly escortthem to the captain.

Victorino Escoto aims to please hisvisitors. The slight captain greets themeagerly and smiles often. Standing by, hisburly chief mate offers sodas from the

captain’s fridge, the familiar red Coca-Cola can accented with Asian charactersfrom a faraway port. Courteous but allbusiness, the Coast Guard inspectors askto see the ship’s documentation.

Captain Escoto gathers several over-stuffed binders and lays them on a tablefor the Coast Guard to review. Eachbinder contains sets of meticulouslyorganized documents, mostly pertainingto things like crew lists, emergencyprocedures , voyage logs. But one of thefirst binders examined has an environ-mental purpose: the Ballast WaterManagement Plan.

While the captain and crew tend tothe inspectors, dockworkers operatemechanical claws, grabbing sugar out of

4 • Chesapeake Quarterly

By Jessica Smits

A QUESTION OF BALLASTProtecting Ships,

Preventing Species Invasions

the ship’s large red bins and dumping itonto a conveyer belt heading into therefinery. When the unloading is complete,the Tamoyo Maiden will depart empty.Empty that is, except for water.

To prepare for the ship’s next journey,Chief Mate Rodelito Lardizabal willdirect crewmembers to fill the ship’s bal-last tanks with Patapsco River water.Without ballast water and without cargo,Lardizabal says, the ship’s propeller andrudder may not even sink below the sur -face . Water weight provides stability andmaneuverability to the Tamoyo — and tohundreds of other ships in the global fleetthat travel with ballast water every day.

But when the crew of the TamoyoMaiden fills its ballast tanks alongside the

Domino pier, they’ll bring more aboardthan water. Grates on the intake pipes willno doubt keep out large fish, but smallerorganisms — larvae, algae, microbes, cysts— will likely slip through as unwittingstowaways. When discharged in anotherport, hitchhikers like these can cause eco-logical catastrophe.

In 1982, the comb jelly, Mnemiopsisleidyi , arrived in Europe’s Black Sea in bal-last from North America — perhaps evenfrom the Chesapeake Bay. The comb jellyfunctions as an important component ofthe food web in the Chesapeake, but inEurope its insatiable appetite was blamedfor decimating fisheries already in decline.

In 1988, the zebra mussel, Dreissenapolymorpha, a native of the Caspian Searegion, first showed up in the NorthAmerican Great Lakes. Since then, thiscolonizing filter feeder has cost billions ofdollars in damages by clogging infrastruc-ture at places like water treatment facilitiesand power plants.

Global shipping is the prime moverbehind most aquatic invasions, accordingto Greg Ruiz, one of the world’s leading“invasion ecologists.” As the head of theMarine Invasions Research Laboratory atthe Smithsonian Environmental ResearchCenter (SERC), Ruiz sits at the hub ofinvasive species research in the Chesa -

peake and beyond. Organisms arriving inports aboard ships — whether in ballastor attached to hulls — often find anecosystem already degraded by intensehuman activity. He thinks debarking intoa degraded environment may make it eas-ier for a non-native species to establishitself as an invader.

The comb jelly and zebra mussel inva-sions brought national and internationalattention to ballast water’s role as a path-way for the introduction of non-nativespecies. Decades later, scientists and man-agers are still asking — how can we pro-tect the environment and keep ships mov-ing safely around the globe?

Fate Hangs in the Ballast

Three months before arriving in theChesapeake Bay, the Tamoyo Maiden’screw filled nine of twelve ballast tankswith water from the port of Onsan,South Korea. Steel products on boardprovided additional weight. After stop-ping to offload goods in several countries,the ship arrived in Coatzacoalcos,Mexico, where it picked up sugar boundfor Baltimore and emptied its nine tanks.But the water it discharged in Mexicowas not from Korea.

Along its route, a little more thanhalfway between Japan and Hawaii, the

Volume 8, Number 2 • 5

Longtime Baltimore landmark, the Domino Sugar refinery takes Mexican sugar from theTamoyo Maiden, a freighter flagged in the Philippines (left). Like a kid in an oversized sandbox, adockworker scrapes raw sugar from massive bins in the ship’s hold (above). When the sugar’s gone,the Tamoyo will take on ballast water from the Patapsco River before heading out to sea. PHOTO S BY

JESSICA SMITS.

ship opened its valves andturned on its ballast pumps.Seawater from the middle of thePacific Ocean rushed into thetanks, forcing out Korean coastalwater. The entire process — so-called “mid-ocean exchange” —took several hours. This swap-ping of water was done for onereason: to avoid potential inva-sion by non-native species.

The theory behind ballastwater exchange is that organ-isms suited to the saltier openocean will not survive in coastalenvironments and, in turn, thatcoastal organisms won’t survive the highseas. In 1993, in response to the zebramussel invasion, the United States firstmandated that ships coming from foreignports to the Great Lakes exchange ballastwater offshore. In 1998, they broadenedtheir reach and called for all vessels enter-ing any U.S. port from abroad to volun-tarily exchange their ballast water outsidethe Exclusive Eco nomic Zone (EEZ) —at least 200 nautical miles offshore. Afterlow voluntary compliance, exchangebecame mandatory in 2004. The UnitedNations Interna tional MaritimeOrganization (IMO) calls for similaraction.

Ruiz finds “very convincing evi-dence” that these policies have reducedconcentrations of coastal organisms indischarged ballast. He believes that ballast

water exchange has likely preventedinvasions .

He’s also quick to point out exchange’sshortcomings. Residual coastal water andorganisms can stay behind in ballast tanks,even after exchange. Just how many for-eign organisms remain, and what theymean for the risk of invasion, is highlyvariable and subject to debate.

Ruiz also notes that exchange is notalways practical for seagoing vessels, andoften not required. According to ananalysis by the U.S. Coast Guard, about65 percent of all ships arriving to U.S.ports from outside the EEZ don’t have toexchange ballast because they didn’t travelmore than 200 miles from any shore. Thiscan include ships coming up from SouthAmerica and passing through the Carib -bean, for example. The number of shipsnot exchanging ballast is even higher

when you include coastwise vessels —ships visiting ports along the same coast.

And then there’s the issue of safety. In July 2006, the Cougar Ace, a car

carrier on its way from Japan to NorthAmerica, began ballast water exchange offthe Aleutian Islands. When its starboardballast tanks failed to refill properly duringthe exchange, the huge vessel rolled to theportside, unable to right itself. Tragically,one rescuer died in the salvage effort.

To guard against accidents like this,regulations allow exceptions for safetywhen — during bad weather, for example— conducting an exchange could jeop-ardize the ship or crew.

Kathy Metcalf, director of maritimeaffairs at the Chamber of Shipping ofAmerica, thinks ballast water exchange isproblematic in any situation. She hasstrong feelings about the requirement.

6 • Chesapeake Quarterly

Disaster at sea can result ifballast tanks fail. That’s whathappened to the car carrier, CougarAce (left), during an open-oceanballast exchange. While such acci-dents are rare, many see them asone more reason to find an alterna-tive to exchange. Intense scrutinymarks the face of U.S. Coast GuardEnsign Jerome Brown as he studiesthe Tamoyo Maiden’s records, withCaptain Escoto looking on (above,right). A three-hour port inspectionof the ship includes reviewing ballastwater management documents andexamining the trim of the hull(above, left). PHOTO S ABOVE BY

JESSICA SMITS.

Kevi

n Be

ll

“Exchange,” she says, “is horrible.” Sheadds that ballast exchange burdens thecrew, who should be concentrating onsafely operating the vessel, and that itdoesn’t provide sufficient protection tothe marine environment.

Metcalf ’s opinion matters. An attorneyand former ship officer for Sunoco, shenow represents the shipping industrybefore Congress and is a member of theU.S. delegation to the IMO’s MarineEnvironment Protection Committee. Butit’s not that she thinks ballast watershouldn’t be managed. “The environmentdeserves it,” she says.

She just sees another way. “The ship-ping industry in general would prefer tohave economically viable, environmentallybeneficial treatment systems.”

Don’t Exchange It, Treat It

Just around the river bend from theDomino Sugar refinery, the MV CapeWashington sits in ready reserve. The slate-gray behemoth serves the MaritimeAdministration, an agency often taskedwith supplying food for humanitarianefforts and bringing resources to the mili-tary overseas. If called upon, the CapeWashington can ship out in five days. Onits last mission, the roll-on roll-off carrierferried equipment to Iraq — humvees,helicopters, tanks — and returned homewith similar items in need of repair. Butnow the Cape Washington is helping with adifferent sort of mission.

Deep in a corner of its cavernousunderbelly, a maze of pipes and hoses hasreplaced military equipment. A team ofcasually dressed biologists and engineersscurries about, apparently oblivious to thestench of fish and sludge that sours theair. This test facility is part of the Mari -time Environmental Resource Center(MERC), an initiative launched by theUniversity of Maryland Center forEnvironmental Science (UMCES) andthe Maryland Port Administration. Theirgoal? Address environmental issues facingthe shipping industry. Priority numberone: ballast water.

Mario Tamburri, a researcher at theUMCES Chesapeake Biological Labora -

tory, directs the Center. He talks fast andexudes enthusiasm. “Ships were notmeant to do this,” he says, referring toballast water exchange. “It was an interimsolution .”

For well over a decade, Tamburri andothers have worked on what they thinkcould be a better solution: treating ballastwater to eliminate the life within it.Filters, oxygen strippers, UV rays, biocides— no matter the method, the idea is thesame. An effective treatment system couldremove invasive species while abolishingthe need for exchange at sea.

It’s an idea that’s recently gained sig ni -ficant traction with environmentalists, gov-ernments, and the shipping industry alike.

MERC was launched after the Mary -

land Port Administration and Con gress -man Elijah Cummings approachedUMCES president Don Boesch abouttackling the issue of ballast water and inva-sive species. The Port had funded projectsinvolving treatment technology in thepast, but the trend was moving away fromindividual scientists’ academic projects andtoward real-world implementation.

In the real world, standardized testingis key. Otherwise systems won’t winapproval, or certification, from flag statesaround the globe. As part of an interna-tional convention for managing ships’ bal-last water, the IMO has issued guidelineson testing and a “discharge standard” fortreatment systems (see Navi gating BallastWater Management, p. 10). But companies

Volume 8, Number 2 • 7

Maritime Environmental Resource Center director Mario Tamburri (top) oversees testing ofballast water treatment systems. New technologies come in large containers like the one housing thefilter -UV apparatus (bottom left). George Smith tests treated water with a probe, while Tim Mulladyrecords the results. The two Smithsonian Environmental Research Center biologists form part of amulti-institutional team studying how treatment systems affect ballast water. PHOTOS BY JESSICA SMITS.

Ballast water isn’t the only way that non-native species move from place to place.How we work and play and even some

of our cultural traditions can all contribute tothe spread of potentially invasive animals,plants, and microbes. The study of thesepathways — a field called vector ecology —has emerged as a key part of efforts to avoidspecies invasions. Here’s a look at some of thetop vectors on the minds of scientists andmanagers.

Hull Fouling

While organisms transported inside ballasttanks seem to garner the most attention,those attached to the outside of a ship maybe equally — or more — to blame. “It’s notjust about ballast,” says invasive species expertGreg Ruiz of the Smithsonian EnvironmentalResearch Center (SERC). “There’s pretty goodevidence, both within the Chesapeake and ona national scale, that hull fouling is reallyimportant as well.”

Attached to the hulls of commercial ships,fouling organisms like mussels, barnacles, andencrusting algae can spread around the globe.Researchers at the SERC Marine InvasionsResearch Laboratory study ways to stem foul -ing through the use of special paints and otherphysical means. In the coming year the SERCscientists plan to work with the Mari time Environmental Resource Center as it also divesinto the hull fouling arena. An added incentiveto fix the problem? Bio foul ing increases drag,which increases travel time and fuelconsumption .

But com-mercial shipsare not theonly culpritsfor spreadingfoulingorganisms.While ballastwater likelybrought thezebra musselto NorthAmerica,recrea tionalboats havelargely contributed to the bivalve’s spread —so-called secondary invasions — throughoutlakes and rivers of the midwest, south, andnortheast. In the fall of 2008, six zebra musselsshowed up near the lower Susquehanna River— one on a boat hauled out for the winter.This year, the Maryland Department of Natu-ral Resources (DNR), with additional supportfrom Maryland Sea Grant, sent all boat regis-

8 • Chesapeake Quarterly

PATHWAYSthat develop the technology don’t neces-sarily have the expertise to measure bio-logical effects — things like how muchlife remains in the water and how dis-charge of treated water may affect sur-rounding water quality. With experiencedbiologists from area institutions like theUniversity of Maryland and the Smith -sonian Environmental Research Centeronboard, Tamburri says, MERC cananswer these questions.

MERC solicits applications fromtechnology companies who want to test asystem in order to move it along in theapproval process. And as an independentthird party, Tamburri notes, MERC lendscredibility to the test results. “You don’twant an infomercial from the company.”

With the onset of spring blooms ofplankton in the Chesapeake, MERC hasjust begun its second season of testing.According to Tamburri, the Bay providesideal conditions to challenge the systemsbecause a mixed bag of phytoplanktonand zooplankton abound from springthrough fall. The system under reviewtoday will use a filter and UV light — aone-two punch to remove organismsfrom the water.

The Cape Washington’s ballast tanks areeach filling with water from the Patapsco.The turbid water, rich in life, enters theship and then splits into two separateobstacle courses of piping.

One pipe sends the water straight intothe starboard tank — the experimentalcontrol. The second pipe includes adetour to a white box, about the size of asmall trailer, containing the treatment sys-tem. Before entering the portside tank,the water moves through the filter toremove sediment and organisms largerthan about the size of a speck of pollen(25 microns). Then the water coursesthrough a stainless steel drum containingbulbs of high intensity UV light. The UVrays pulse the water before it finallyenters the portside ballast tank.

While engineers monitor the flowthrough the treatment system, biologistsdivert about one cubic meter of untreatedballast water into a large plastic jug. Oncethe jug is full, they work quickly to col-

lect samples for a whole suite of analyses. They dip a probe into the tea-colored

water to measure physical properties liketemperature, acidity, dissolved oxygen, andsalinity. This afternoon they’ll examinesamples under a microscope to identifyand count the living organisms.

Addi tional samples will go back to thelab for chlorophyll analysis and tests forbacteria. All together, this collection ofwork will show the initial conditions ofthe untreated water.

The team then does the same forwater that’s passed through the treatmentsystem. This gives them a read on theconditions of the water soon after itcourses through the filter and UV rays.

Water stays in the two ballast tanks forfive days, mimicking the length of anaverage journey at sea.

When they return the next week, theMERC team begins to pump out thetanks. They carry out the exact same pro-tocol as they did days before, gatheringdata on how life and conditions withinthe two tanks have changed over theholding period.

As they prepare for sampling, theytake a look at treated water running outof blue hoses into a tub. “Looks goodenough to drink,” one of the biologistsquips. Although this quick assessment isnot a judgment on the system’s success,the contrast is stark between the brown,smelly untreated water that came in thepipes last week and the clear treatedwater now flowing through the hoses.

Did this filter combined with UVradiation work?

Roadblock to Implementation

MERC can answer only part of thatquestion. They’ll compile data from thetrials and provide results to the companydeveloping this treatment system and toany governments or organizations itrequests. But after they provide the data,it’ll be up to others to decide whetherthis treatment method meets theirstandards and whether to allow it as analternative to exchange. And that roadgets complicated .

Zebra mussels

Continued on p. 10

tration holders a flyer urging them to takeextra steps to clean their boat, trailer, or divegear.

Live Trade

Global commerce has made it easier thanever to exchange goods — and non-nativespecies. Greg Ruiz thinks the trade of liveplants and animals is playing an increasing rolein aquatic invasions. But this market is con-stantly in flux, he says, and scientists don’tknow enough about it.

Seafood

The discoveryof snakeheads ,pred atoryAsian fish, in aCrofton,Mary landpond in 2002captured sig-nificant atten-tion and ledto a successfuleffort to erad-icate them in the pond. A local resident ulti-mately admitted to having released two snake-heads into the pond after purchasing them ata live seafood market in New York. Anotherintroduction in a Virginia creek has led tosnakeheads thriving throughout the PotomacRiver and tributaries in Virginia and Maryland.

Aquarium Pets

Exotic aquarium pets can also wind up in anew environment. Jonathan McKnight, co-chairof Maryland DNR’s Invasive Species MatrixTeam, notes that pacu fish, a South Americanspecies that closely resembles a piranha and ispopular with aquarists, have periodically shownup in Maryland waters. Ruiz says such intro -ductions to the wild usually occur whenpeople no longer want to take care of theirpets. Working with the Maryland Associationof Pet Industries, DNR and Maryland SeaGrant have produced a poster for use in petstores advising pet owners not to release non-native animals into the environment.

Bait

Unused baitdiscarded intoa waterway atthe end of aday’s fishingalso leads toinvasions.McKnight

notes that non-native species are widely avail-able in bait shops throughout the area. This isprobably how rusty crayfish, native to parts ofthe midwest, ended up in Maryland. Blamedfor displacing native crayfish and preying onplants and invertebrates, “rusties” are now ille-gal to use as bait.

Fishing Gear

Along withboats, fishingequipment canalso serve as avector for inva-sion. Wadinggear can carrymicroscopicorganisms fromone stream tothe next.McKnight notesthat the ten-dency of fly fish-ermen to travel— Montanaone weekend,Maryland thenext — compli-cates theproblem .

In 2008, thediscovery of aninvasive algae referred to as Didymo (shortfor Didymo sphenia geminata) spurred sharpervigilance in Maryland. Also called “rock snot,”the algae can form slime-like mats that coverstream bottoms, smothering life. To combatthe spread of Didymo and other invasiveorganisms like it, Maryland DNR asks fisher-men to use rubber-soled waders — ratherthan felt, which can hold more water andmore organisms — and to disinfect gear withdetergent or salt solution .

Water Gardens

Invasive plants used in aquatic gardens pose athreat as well. Pond owners who dispose ofplants improperly or ponds that overflow in heavy rains can introduce non-native species

into local streamsand rivers. In2007, officialsfound water let-tuce, an attractivebut troublesomeweed, in Matta-woman Creek, atributary of thePotomac River.Biologists say non-natives like this can crowdout native plants, block sunlight, deplete oxy-gen, and even impede boating. Since water let-tuce is tropical, its presence here provokesanother question. Will rising temperaturesallow warm-weather species like this to sur-vive and spread farther north?

Intentional Introductions

Honeybees, cattle, carp. Non-native speciesdon’t always appear by accident. Often they’reintroduced as part of a larger plan — toboost agriculture, the fishing industry, recrea -tional activities, the list goes on. But evenspecies meant to enhance our quality of lifehave the potential to cause unintendednegative con sequences .

In the 1950s, semi-aquatic rodents callednutria were introduced to Maryland in aneffort to promote the fur industry. The highlyprolific animal eventually overran ChesapeakeBay marshes, destroying vegetation and out-competing native muskrat. Decades later, amulti-agency partnership to control the nutriapopulation through trapping and hunting hassuccessfullycleared over150,000 acresof nutria. Butwork remains asmanagers con-tinue to inspecthundreds ofthousands ofadditional acres.

More recently, a proposal to introduce anAsian oyster, Crassostrea ariakensis, in theChesapeake showed how heated the issue ofintentional non-native species introductionscan get. While some argued that the introduc-tion could help restore oysters to the Bay, oth-ers cried foul. They argued that the non-nativeoyster could bring disease and unforeseenproblems to the Bay. In March 2009, afteryears of studying the issue, state and federalofficials announced that they had abandonedthe idea of bringing in the non-native oyster— at least for now.

— J.S.

Volume 8, Number 2 • 9

FOR INVASIONS . . . . . . . . . . . .

A grab bag of non-native species — fromrepulsive rock snot to attractive water lettuce —lives in the Chesapeake and its tributaries .PHOTO CREDITS: ZEBRA MUSSELS, NOAA; SNAKEHEAD,

U.S. GEOLOGICAL SURVEY; BAIT, MATTHEW SELL; FISHING

GEAR, STEPHEN WITHERDEN; DIDYMO, MARYLAND

DEPARTMENT OF NATURAL RESOURCES; WATER LET-

TUCE, NANCY RYBICKI; AND NUTRIA, CAROL A. HOLKO.

Snakehead

Water lettuce

Rustycrayfish

Didymo

Nutria

10 • Chesapeake Quarterly

Navigating Ballast Water Management

Over the past two decades, managing the discharge of ballast water has evolved into acomplicated tangle of international, federal, and state law — and lawsuits. Here’s a

glimpse at what’s happening now.

International

On the global stage, the International Maritime Organ-ization, a United Nations agency focused on shippingsafety and pollution, has developed a legal frameworkto regulate ballast water. In February 2004, at a diplo-matic conference in London, representatives frommember countries adopted a treaty with a very longtitle: the International Convention for the Control andManagement of Ships’ Ballast Water and Sediments. Inaddition to a ballast water exchange standard, theconvention created discharge standards for treatmentmethods (for example, the number of living organismsthat can remain in the water). The convention allowscountries to create their own stricter standards — animportant stipulation for the United States, whichreportedly lobbied for more stringent discharge stan-dards than those finally adopted. For the conventionto enter into force, 30 countries, representing 35 percent of the world’s merchant shippingtonnage, must sign on. The U.S. has not yet ratified the treaty.

Federal

In the United States, the Coast Guard regulates ballast water management under theNational Aquatic Nuisance Prevention and Control Act of 1990, later reauthorized as theNational Invasive Species Act of 1996. Starting in 2009, the Environmental Protection Agency(EPA) is exercising regulatory authority as well.

Why the shift? In 2003, environmental groups brought a lawsuit against the EPA for failingto regulate ballast water as point-source pollution under the Clean Water Act. The EPA hadexempted ballast water as a point source and later noted that Congress had directed theCoast Guard, not them, to regulate ballast water. After years of appeal, in 2008, the NinthCircuit held that the EPA could no longer exempt ballast water or other discharges normalto the operation of a ship.

Forced to enter the ballast water arena, the EPA created a blanket permit that, in effect,called for following the Coast Guard’s ballast water regulations. This so-called Vessel GeneralPermit, which went into effect in February 2009, disappointed some states and environmen-tal groups that hoped EPA would use this opportunity to enact stricter ballast protocols. TheCoast Guard reports that it’s working with the EPA to minimize complications that couldarise with two different agencies, working under different statutes, regulating the same thing.

And the situation continues to evolve. The EPA’s new administrator, Lisa Jackson, told theGreat Lakes Commission that the permit “doesn’t begin to address some of the concernsthat are out there.”

State

Many states have taken ballast water management into their own hands. Fearing that federal(and international) policies don’t do enough to protect their waters from invasive species,some states require ships to take additional measures before discharging ballast water intheir ports. California, Oregon, and Washington, for example, require coastwise vessels toundergo ballast exchange 50 nautical miles from shore. California has also developed treat-ment standards that call for zero organisms in discharged ballast water by 2020. Recently,many states took advantage of a provision in the Clean Water Act that allowed them torequire vessels to meet more stringent state standards than those included in the EPA’s newVessel General Permit.

The shipping industry largely denounces state measures as patchwork regulations thatcomplicate their ability to do business. “A vessel that goes to New York has to do one thing,but when it goes to Baltimore, it’s got to do something else,” says Kathy Metcalf of theChamber of Shipping of America. She says the industry wants a federal ballast water man-agement program that creates one national standard and preempts states from “creatingtheir own and often conflicting programs.” “My organization can support the most stringentstandard necessary that is technologically achievable,” she says. “As long as it’s the only stan-dard around the nation.” Environmentalists and concerned states want to make sure that anynational standard is in fact stringent.

— J.S.

Ballast, continued

If the results from the MERC tests lookpromising — that is, if they meet standardsset by the IMO — this filter-UV treatmentsystem will move into the shipboard testingphase. This requires operating on a ship atsea under real-life conditions. Success theremeans the developer can ask a ship classifica-tion society, such as the American Bureau ofShipping, to approve the system as techni-cally sound and safe for use on a ship. Fromthere, the company will approach flag statesfor certification as a ballast water treatmentsystem that meets IMO standards andrequirements.

For now, one thing is certain. The UnitedStates will not be approached for certification.The federal government currently does notrecognize treatment as a ballast water manage-ment tool — exchange is the only option.

Mario Tamburri notes that the first treat-ment technology to be certified was a deoxy-genation system developed by NEI TreatmentSystems, based in Los Angeles. Although thesystem was tested using federal grants from theNational Oceanic and Atmospheric Adminis -tration (NOAA), NEI could not seek approvalfor use in the United States because the U.S.does not yet have a procedure in place forapproving systems. So, Tamburri says, the U.S.-based company packaged all their informationand submitted it to Liberia — commercialshipping’s second largest flag state.

According to Coast Guard biologist RichEverett, the U.S. is moving toward replacingexchange with treatment. Everett has beeninvolved in writing regulations to that end.He acknowledges that the Coast Guard hasfinished drafting regulations and that they’regoing through a formal review process withother agencies. How close are they topublishing it as a proposed rule? Everettwould not comment except to say that it’simpossible to predict because of the manyimportant issues facing the government .

Tamburri is hopeful that publishing theregulations is imminent, within the next yearor so. Meanwhile, some states have given upwaiting for the federal government and havecreated treatment regulations of their own(see Navigating Ballast Water Management,at left).

SERC

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Coastwise CodaJust a few weeks before MERC’s trialsbegan for the season, the Tamoyo Maidentook in untreated water — no doubtpacked with microscopic life — less thana mile from where the Cape Washingtonsits. Captain Escoto expected that theirnext port of call would be Lake Charles,Louisiana. As a coastwise voyage the shipwould not be required to exchange itsballast water. In order to take on theiranticipated cargo, the crew planned todischarge their Baltimore Harbor waterinto an artery of the Gulf of Mexico —an entirely different ecosystem from theChesapeake Bay.

Tamburri sees these types of coastalvoyages, where exchange is not required,as potential for trouble. He thinks thebiggest issue is that once there’s an inva-sion in a place like the Chesapeake Bay, itspreads through coastal routes, resulting insecondary invasions.

The Coast Guard’s Rich Everettagrees. He doesn’t know of any biologicalevidence that shows coastwise transport ofballast water poses less of a risk for intro-ducing or spreading an invasive speciesthan transoceanic ballast transport.

West coast states have addressed theissue by requiring most coastwise ships toundergo exchange at 50 nautical milesoffshore. Everett says this is consideredeffective on the west coast because thecontinental shelf is narrow and a ship canbe in deep oceanic water — rather thancoastal water — without having to detourtoo far out of the way. The oceanographicconditions created by the narrow shelfalso reduce mixing of offshore andinshore waters. All of this decreases thelikelihood that non-native coastal organ-isms discharged only 50 miles out wouldwind up reaching inshore habitats.

On the east coast, the continentalshelf is much broader, and vessels have toventure farther offshore for effectiveexchange, an impractical option on coast-wise trips.

Tamburri and Everett think that iftreatment becomes mainstream it couldhelp solve issues like this. A treatment sys-tem could operate without forcing a ship

to divert from its course or to carry out arisky exchange. A win for industry. And atreatment system could run in situationswhere exchange is not required. A win forcoastal environments.

The Tamoyo Maiden never made it toLouisiana. Before leaving Baltimore,Captain Escoto got different orders —not unusual in an industry whose logisticsdepend on the dynamic flux in demandfor goods around the globe. The changein itinerary sent the cargo ship up theAtlantic coast to the Saint LawrenceRiver and on to Montreal. The Gulf ofMexico got a reprieve from Baltimorewater. At least this time.

Along the way to Montreal, hundredsof miles off Long Island at the edge of thecontinental shelf, the Tamoyo once againopened its valves and turned on its ballastpumps. Water from the Atlantic Oceanflowed into the tanks, and a piece of thePatapsco River flowed out into the sea.

Canadian law called for this exchange.The St. Lawrence has been burned before.Years ago, a ship headed toward the GreatLakes entered here, unaware that it carriedthe devastating zebra mussel in its ballasttanks. For now, ballast exchange providessome defense again the next invasive mus-sel or crab or microbe. But it is an imper-fect defense, and many hope that therewill soon be a better one.

— smits@mdsg.umd.edu

Volume 8, Number 2 • 11

For More Information

Maritime Environmental Resource Centerwww.maritime-enviro.org/

Marine Invasions Research Labwww.serc.si.edu/labs/marine_invasions/

National Ballast Information Clearing-house http://invasions.si.edu/nbic/

United States Coast Guard Ballast WaterManagementwww.uscg.mil/hq/cg5/cg522/cg5224/bwm.asp

Global Ballast Water ManagementProgramme http://globallast.imo.org/

Mid-Atlantic Panel on Aquatic Invasive Species www.midatlanticpanel.org/

Maryland Sea Grant www.mdsg.umd.edu/exotics

Vector Management Workshop

November 17, 2009,Washington D.C. Region

Maryland Sea Grantand the Mid-AtlanticPanel on AquaticInvasive Species willconduct a one-dayworkshop to bringregional attention to

aquatic invasive species introductionpath ways. The workshop goal is todevelop strategies states can pursue tomanage vectors to prevent unwantedintroductions of non-native species.For details, visit www.mdsg.umd.edu/vectorworkshop .

Rapid Response Planning

While preventing invasions is key, managers must also be prepared totake action when prevention measures fail. To foster an effective

response to aquatic invasive species introductions, Maryland Sea Grantand the Mid-Atlantic Panel on Aquatic Invasive Species worked with theirpartners to produce Rapid Response Planning for Aquatic Invasive Species.

The rapid response plan employs Incident Command System (ICS), aresponse framework best known for its application to environmental dis-asters like wildfires and oil spills. ICS provides a common language and astep-by-step approach to organizing response efforts. It aims to help indi-viduals from various agencies and jurisdictions work together as a well-coordinated unit. Use ofICS for invasive species incidents — a relatively new endeavor — is backed by the congression-ally mandated Aquatic Nuisance Species Taskforce.

The Rapid Response Plan is available in two formats: (1) A Template and (2) A MarylandExample.

The template is available as a Microsoft Word document to encourage states in the Mid-Atlantic and beyond to adapt the plan to their specific needs while maintaining a commonframework across the region. Maryland was the first state to complete the template, and itsresulting plan is available for use as an example. Anyone may download both the template andMaryland example at www.mdsg.umd.edu/rapidresponse. The state of Delaware has also usedthe template and is currently finalizing its plan.

Mat

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Skeptics question whether an invasivespecies has ever really caused significantecological damage in the Chesapeake Bay.

The answer is yes. We called it MSX.It was like the plague for oysters, and it

came from somewhere else. In 1959, whenMSX showed up in Virginia’s Mobjack Bay, onemillion oysters died. In a single year. If oysterswere once hailed as “white gold,” then MSXwas the White Death.

More than a nuisance, when this exotic par-asite appeared in Chesapeake and Delawarebays in the late 1950s, it destroyed the richestoyster fisheries in the world. It also killed theregion’s best reef builder and filter feeder.

What about Overharvesting?

Some might argue that the Bay’s oystermenhad — through decades of aggressive harvest-ing — already destroyed their golden goose.And there is some truth in that. By knockingdown the old bars, watermen not onlyremoved bargeloads of oysters from the Bay,but they left the remaining oysters lying on thebottom. Increasing clouds of sediment coveredthem. Boring sponges and other predatorsattacked them.

But it’s also true that during the middle ofthe 20th century the Chesapeake oyster fish-

ery had reached something of an equilibrium.Though down from the reckless white goldrush of the 19th century, for much of the mid-20th century Baywide oyster harvests fluctu-ated roughly between 20 to 30 to 40 millionpounds, year after year. In 1980, in the Mary-land portion of the Bay, watermen entering thefishery saw about the same oyster harvesttheir parents had seen when World War IIended in 1945. About the same harvest Mary-land watermen had pulled in as far back as thelate 1920s.

Baywide, the oyster harvest — though at areduced level and constrained by gear restric-tions and other rules — found a kind of sus-tainability. In the 1950s, the Bay was in decentshape. Underwater grasses still lined the shal-lows. Oysters, crabs, and fish were still in goodsupply.

Then one day as the 1950s came to aclose, a foreign parasite showed up. And thatchanged everything.

Where Did It Come From?When oysters began dying in droves in theDelaware and Chesapeake bays, oyster scien-tists rushed in from around the country. It wasnot white gold that brought them, but theWhite Death. They looked at slides beneaththeir microscopes and found a profusion of

round cells (plasmo dia),filled with multiplenuclei. They comparedthese with oysterparasites they’d seenbefore — but theyfound no match.

Stumped, theynamed the unfamiliarorganism “Multinucle-ated Sphere Unknown,”or MSX.

Forty years passedbefore tools turned upthat could pull MSXfrom a global lineup ofoyster parasites. Thanksto genetic detectivework by researcherEugene Burreson and hiscolleague Nancy Stokesat the Virginia Institute ofMarine Science (VIMS),we now know that thisoyster killer came fromAsia, almost certainlyfrom Japan and Korea,after World War II andthe Korean War.

The parasite lives inthe Japanese oyster,Crassostrea gigas, usedfor aquaculture in manyplaces around theworld, including the

northwest U.S. Records show that scientistsand oyster growers also brought the Japaneseoyster to the east coast, to see how it woulddo. Ships returning from duty in Japan andKorea may also have unwittingly brought backnon-native organisms, including the oyster par-asite. Exactly how MSX got here makes for afascinating story and some intriguing specula-tion (see Who Killed Crassostrea Virginica? onp. 13).

But wouldn’t Bay oysters have fought offthis foreign invader if decades of overharvestingand habitat destruction hadn’t already weak-ened them?

Burreson doesn’t think so. Based on theway MSX swept through healthy oyster barswhen it first showed up here, he thinks thatoysters would have succumbed anyway. Theirimmune systems simply had not evolved tohandle this invading parasite. Like other dis-eases — the chestnut blight, Dutch elmdisease , small pox — when this parasite fromthe Old World reached America it found littleresistance.

After MSX invaded Dela ware, Virginia, andMaryland, it marched up and down the Atlanticcoast. In the 1980s, it appeared as far south asFlorida and as far north as Maine. In 2000,MSX killed a large number of oysters in NovaScotia, Canada.

12 • Chesapeake Quarterly

KI L L E RFrom across the Sea

By Jack Greer

of hope. The diseases are still out there, butdespite dry weather over the last couple ofyears they haven’t killed as many oysters as inthe past. Are Mary land’s oysters developingsome natural resistance? Maybe, he says. Wewon’t know until we have “empirical evi-dence.” The best thing we can do now, he says,is to leave the large survivors in the Bay. Heargues that we need sanctuary areas wheresurviving oysters can reproduce and pass ontheir ability to resist disease. And then we haveto wait.

Still a Mystery

Despite all we’ve learned about this devastatingparasite, there’s good reason to keep the X inMSX.

Though scientists long ago characterizedthe single-celled organism — first naming itMinchina nelsoni in 1966 and then Haplo spor i -dium nelsoni in 1980 — they still haven’t figuredout its lifecycle. Or even how it infects its oys-ter victims.

Burreson still puzzles over this and hasdevoted endless hours in the search for anintermediate host — an organism that hebelieves plays a key role in how oystersbecome infected and how MSX manages tomove around so fast and so far. He says it’shard to find continued funding for this work,though, and next year he plans to retire.

“Someone will get lucky one day and juststumble on it,” he says. “They’ll say, ‘Gee, what’sthis doing here?’” He goes on to say, “I hopethis happens before I drop dead. I want toknow what it is.”

What’s the future for oysters and MSX in theBay? Burreson actually feels “some opti-mism”— since oysters in high salinity areasnow appear to show signs of resistance. Thebigger problem now, in Virginia as in Maryland,is that other oyster parasite, Dermo.

This leads Burreson to ask another ques-tion. Is there some as-yet-undiscoveredconnection between Dermo and MSX? Somehidden relationship? We know that Dermowas already in the Bay before MSX showed up.Researchers found it in 1949, the first timethey went looking for it. But it wasn’t until MSXappeared ten years later that Dermo becamea real problem. Cause and effect? Or justcoincidence ?

That’s a hot topic for his younger col-leagues to take on, Burreson says. For now he’llhave to be satisfied with being part of theteam that figured out where MSX came from.That will go down as a pivotal discovery —especially for those who want to know justwhat kind of damage a non-native parasite cando to a major fishery, and to a national treas-ure like the Chesapeake Bay.

— greer@mdsg.umd.edu

Volume 8, Number 2 • 13

T he remarkable story of howscientists found the origins of

MSX and their speculations abouthow the parasite ended up in theChesapeake and Delaware bays is

now the subject of a new documentaryby Maryland Sea Grant, Who Killed CrassostreaVirginica? The film traces the decline of the Bay’snative oyster and the fatal blow brought byMSX and another prevalent disease, calledDermo.

Produced, written, and directed by veteranfilmmaker Michael W. Fincham , the film capturesboth the poignant destruction of a fabled fish-ery and the prolonged scientific inquiry into theorigins of the killer parasite. Painting a fair pic-ture of the Bay’s oyster heritage is a toughassignment. On the one hand the Bay’s water-men are its iconographic characters, as nativeto this region as bullfighters are to Spain. Onthe other hand, their graceful skipjacks pulleddredges that brought down the Bay’s virgin oys-ter reefs.

The film asks whether we can save both theoyster and the oystermen. And it peers towarda future where the Bay’s historic oyster groundsmay shrink to areas where disease does notdominate. The film premiered this spring at theSmithsonian Museum of Natural History, aspart of the annual Environmental Film Festival,and it will be released for broadcast in Septem-ber 2009. For more information, visit the webat www.mdsg.umd.edu/oysterfilm.

Who Killed Crassostrea Virginica?

Virginia landings

Maryland landings

Dermo found inChesapeake Bay

MSX found inChesapeake Bay

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Ghosts of a bygone fishery, abandoned Bay workboats (opposite page) bear witness to the passingof what was once the world’s richest oyster industry. On the oyster landings graph above, the high har-vests of the nineteenth century trace the dismantling of the Bay’s virgin oyster reefs. Only after the1920s did Chesapeake oyster harvests stabilize, shoring up a substantial fishery. That changed in 1959when an exotic parasite called MSX hit. The Virginia oyster harvest plummeted first. Mary land’s fisheryhung on until the early 1980s, then several years of drought brought disease riding up the Bay on awedge of saltwater. The Bay’s oyster populations have still not recovered. PHOTO BY MICHAEL W.

FINCHAM. GRAPH ADAPTED FROM A NOAA CHESA PEAKE BAY OFFICE GRAPH.

MSX Today

As the Bay moves into the 21st century, MSXis “everywhere” in the saltier reaches, accord-ing to Burreson.

But even so, it may be that the shadow ofMSX is finally lifting. At least in the lower Bay.

“It’s still killing first-year spat [baby oys-ters],” says Burreson, “but not so much adults.”In Virginia, he’s seen that once oysters reachtheir second year, they seem to do okay. It’s asimilar story in Delaware Bay. Veteran oysterresearcher Susan Ford at Rutgers Universitytells him she’s seeing the same pattern.

In both Virginia and Delaware, whereMSX has hammered away relentlessly fordecades, oysters have developed an apparentresistance .

Says Burreson, “It’s taken fifty years.”But the saga of MSX is far from over. In

Maryland, where it takes a drought to bringsalty water up the Bay, oysters see MSX onlyat intervals. Burreson thinks they haven’t hadtime to develop the same tolerance as oystersin the lower Bay.

Researcher Chris Dungan agrees. He’s atthe Cooperative Oxford Laboratory, aresearch facility on the Eastern Shore createdin 1960 expressly to take on the mystery ofthe new oyster killers. He says that a secondoyster disease, known as Dermo (Perkinsusmarinus), is now more prevalent in Maryland.But ongoing sampling shows that MSX stillcrops up in dry years when salinity rises.

And it still kills. And yet Dungan, too, sees a possible ray

E arly one August morning in 1980, fouryoung scientists from Florida tried to getsome sleep on benches near the Wash-

ington Monument. Soon enough the ParkPolice rousted them and they began wander-ing along the north side of the National Mall.When they reached the lake at ConstitutionGardens, the scientists paused, took off theirshoes — and waded into the water. Whenthe police caught them this time, they werepulling plants out of the lake and studyingtheir roots.

“This is hydrilla,” they told a perplexedpoliceman with little interest in aquatic plants.It was an accidental discovery but an importantone, made by sleep-deprived scientists whohad driven all night to make a meeting. Hydrilla, they explained, was a non-native plantfound mostly in India, Sri Lanka, Pakistan, andother countries bordering the Indian Ocean.What was it doing on the National Mall?

“We didn’t know what hydrilla was,” saidRichard Hammerschlag, the Park Servicescientist who had supervised the plantings.“It wasn’t on our radar. It wasn’t up here.”

Hydrilla was suddenly large on his radar —and not just because it was here on theNational Mall. Hammerschlag knew hydrilla hadspread through much of Florida, clogging canalsand creeks and lakes with thick green mats ofvegetation. And he knew Park Service scientistshad recently put this same invasive grass outon the Potomac River.

Hydrilla has been confusing scientists ever sinceit arrived in America. In 1960 two young scien-tists found hydrilla clogging the Snapper CreekCanal in south Miami, but they had no ideawhat this mystery plant was or where it camefrom. Bob Blackburn had been working inFlorida for one year. His partner, Lyle Weldonhad just arrived. They were the first scientiststo study this plant in American waters, but itwould take them five years to figure out whatit was.

Blackburn and Weldon were part of agroup newly organized by the AgriculturalResearch Service of the U.S. Department ofAgriculture. Eastern Florida with its subtropicalweather and numerous waterways was groundzero for invasions of aquatic plants fromaround the world. The new hires were sup-posed to discover and disable the invaders.

A little detective work turned up the culpritbehind the canal invasion. A homeowner toldBlackburn she put the plant in the water.Something that looked so pretty in her aquar-ium would also look nice in the canal. Wheredid she get the plant? From an aquatic plantdealer who bought plants from overseas andsold them here.

Worried by its rapid spread, Blackburn andWeldon sent plant samples to the University ofFlorida and the Smithsonian Institution in Wash -ington, D.C. and got the same answer backfrom scientists at both institutions: this fast-growing plant was probably American elodea.

The second outbreak was 300 miles awayin Crystal River, and no detective work was

needed to pinpoint the source. An aquaticplant dealer bragged to Blackburn that he hadbeen growing these plants in the river so hecould sell them to people with aquariums andbackyard water gardens. He knew the plantwasn’t American elodea — it was being sold as“Indian Starvine.”

When Blackburn and Weldon kept findingtubers and turions, they went looking for athird opinion and got the same answer: thiswas elodea “with strange growth characteris-tics.” Finally a fourth opinion paid off when theysent samples to Harold St. John, a worldauthority on aquatic plants. Six months laterthey got the telegram: this was not elodea. Itwas hydrilla, a plant native to the Indian Oceanregion. At the launch of their careers theseyoung scientists could now take credit for doc-umenting the arrival of a new aquatic plant inNorth American waters.

They were already driving around Floridaobserving and photographing new outbreaks. Itwas work that brought Blackburn and Weldoninto a partnership unusual in science. As Black-burn describes it, Weldon was a research part-ner, then a friend, and finally almost a brother.They worked together, traveled together, andpublished together.

14 • Chesapeake Quarterly

TRAVELS WITHHYDRILLA

The Unnatural History of an Accidental Invader

By Michael W. Fincham

The famous Reflecting Pool on the National Mall once held an underwater grasscalled hydrilla, as did the nearby Constitution Gar -dens Lake. An invasive species now found in 30states, hydrilla is native to countries in the IndianOcean region. PHOTO BY MICHAEL W. FINCHAM.

And they dove together. Hydrilla, theyquickly saw, was “a canopy former,” and theywanted to see what lay beneath. To see theunderside Blackburn and Weldon began mak-ing scuba dives wearing air tanks, weight belts,and regulators. Sinking below the surface, theydiscovered mats that could grow four to sixfeet thick, blocking out the sun and sendinglong vine-like tentacles twisting down to thebottom. It was, Blackburn remembers, like div-ing into a dark cave.

Hydrilla, they discovered, could snake alongthe bottom quickly, almost secretly, using vine-like runners. Its long stems then reach upwardstoward the surface where they suddenlybranch out in all directions, interlacing to forma canopy. It replicates through seeds, buds, androots, but also through broken shoots that floataway, sink, and quickly latch onto the bottomwith fine, threadlike roots. By spreading throughfragments, the “perfect weed” became a fasttraveler. During the 1960s it showed upthroughout the state. During the 1970s itwould range through out most of the south.

On February 1, 1970, the partnershipended. Blackburn and Weldon dove into ahydrilla-jammed lake next to a Naval base nearOrlando and quickly lost sight of each otherunder the dark canopy. When Blackburn sur-faced he saw no sign of Weldon and doveagain. He finally found his partner floating deadunder the canopy, tangled in long, twistinghydrilla vines.

Blackburn’s guess: “He got under thecanopy and got confused.” Separation, entan-glement, confusion, panic. His mouthpiece lost,his lungs filled with water.

Blackburn never dove again. “I lost my feelfor it that day.”

As Kerry Steward motored down the PotomacRiver in the summer of 1982, he was amazedat how far hydrilla had spread along this hugeriver. A colleague of Blackburn and Weldon, hewas a veteran of the hydrilla campaigns inFlorida, now come north to consult with theNational Park Service. Traveling the Potomacwith a team of local scientists, he was finding aninvasive species that was first discovered 1,000miles to the south.

A local scientist riding with him found thescene breathtaking — even frightening. Smallbays and coves were covered wall-to-wall withgreen mats — like golf fairways laid over partsof the river. It was, he thought, an ecologicalnightmare, an opinion shared by a lot of angryboaters, marina operators, and waterfronthomeowners along more than 20 miles ofshoreline. The “hydrilla wars,” as the localscalled them, were well launched by now in thenation’s capital. Newspapers were runningheadlines about a new “monster” seagrass thatwas invading the river.

Where did the “monster” come from? Andhow to get rid of it? Those were the questionsSteward was hired to solve, according toRichard Hammerschlag, the Park Service scien-tist who brought him to Washington. Like any

good detective, Steward and his team collectedsamples, sent them off to a lab, and inter-viewed local witnesses.

Was the National Park Service a culprit? AtDyke Marsh, a cove of the Potomac just southof Alexandria, one of their scientists had beentesting a pondweed that looked like Americanelodea. Looks can be deceiving, as Stewardknew. The plants he was pulling out of thePotomac looked to his eye like hydrilla, thesame plant that caused so many problems inFlorida.

Was there, Steward asked, another, lessobvious culprit? Who had sold hydrilla to theNational Park Service?

Don Schmitz knows the name of the man whofirst brought hydrilla to Florida, but he’s nottelling. The co-author of a history of aquaticinvasions, Schmitz did enough detective workto track down the first culprit, agent zero forthe hydrilla epidemic. Schmitz not only foundhis man, he got his confession — but only bypromising anonymity.

What Schmitz heard was a tale of mistakenidentities and accidents. The mistakes beganwith a dealer for tropical fish and aquaticplants who imported hydrilla from Sri Lanka(then called Ceylon) to St. Louis, Missouri,thinking he was getting a species of anacharis,a green plant commonly sold for aquariums.Impressed with the plants, he airmailed sixbundles to Tampa, Florida, where anotherdealer, unimpressed, ordered them thrownaway.

The accidents began when his son failed tofollow orders, first storing the exotics in aTampa canal near the airport — and thenpromptly forgetting about them. When theTampa dealer, let’s call him agent zero, later dis-covered the plant spreading throughout thecanal, he promptly changed his mind. Finallyimpressed, he began marketing his mysteryplant to other dealers, calling it “IndianStarvine.” And some of those dealers beganstoring it in canals before selling it for aquari-ums and ponds.

This roundabout route is fairly typical forinvasions of many exotic plants, according toSchmitz. With the expansion of air freight afterWorld War II, the rate of invasions into Amer-ica picked up dramatically. Plants that used todie on long ship passages now arrived readyfor transplanting to new waters.

Much of the transplanting was done bydealers working in the aquarium plant industry.“Dealers deliberately seeded the waterways,”says Schmitz. They would import exotics, oftenstoring them in creeks and canals, a tactic thatsaved them the cost of maintaining so manyponds and tanks. Later they would harvestplants out of the canals and sell them tohomeowners for their aquariums and watergardens. Months or years later many of theircustomers would empty their aquariums intocreeks and canals near their home, seedingnew waterways.

Once in the water, hydrilla traveled easily to

new waters, carried across land as a hitchhikeron boats and boat trailers. Arriving in a newlocation, any fragment could quickly take rootand start snaking along the bottom.

When Schmitz finally tracked down theTampa dealer, his agent zero, they met in arestaurant for sandwiches. The dealer, now wellinto his nineties, made his confession but gotno absolution from Schmitz, who outlined allthe damage done by hydrilla, all the millionsspent trying to eradicate it or control it inFlorida’s waterways.

“I had to ask him, how do you feel about allthat,” says Schmitz. “He leaned back and said,‘Whoops!’”

As he investigated the hydrilla invasion of thePotomac River, Kerry Steward suspected hewas seeing another big whoops: another chainof accidents and mistaken identities that couldbe a repeat of the Florida invasion pattern. Andone possible link in the chain was a local com-mercial dealer in aquatic plants.

Where, he asked, did Park Service scientistsget the mislabeled hydrilla they put in thePotomac River? They told Steward they kepttheir elodea look-alikes at the KenilworthAquatic Gardens, a small riverside park alongthe Anacostia River — but they originallybrought those plants in from Lilypons WaterGardens, a commercial dealer in Adamstown,Maryland. Lilypons in turn often used a supplierin Texas.

Steward sent plants from both KenilworthGardens and Lilypons to his Florida lab for cul-ture and analysis. The results showed thatplants from both sources were hydrilla, notelodea, and both had identical enzyme pat-terns, more evidence that Lilypons was theprobable source of hydrilla. The chain becameclear, says Hammerschlag: “Lillypons to Kenil-worth Gardens to Dyke Marsh.”

And the last link in the chain was the scien-tist who put hydrilla in the Potomac at DykeMarsh.

In the spring of 1980 Horace Wester had aplan. He would put elodea in floating cages,place the cages in the river at Dyke Marsh, andsee how the plants fared under different condi-tions. These cages, five feet long and made ofwood, would float, holding the plants above thedark bottom and closer to the light. His hopewas to begin restoring underwater grasses tothe Potomac. His mistake was using elodeaplants that were actually hydrilla.

It was a mistake made by experts aroundthe country, but it carried sad irony for a scien-tist as experienced and observant as HoraceWester. A native of the Washington, D.C. area,Wester had spent a 40-year career trying topreserve or restore the capital city’s endan-gered natural resources. During the onslaughtof Dutch elm disease he helped save Washing-ton’s famous shade trees by identifying a singletree that seemed resistant. He discovered itstanding in front of the Freer Gallery of Art,and his work led to the cloning of that tree

Volume 8, Number 2 • 15

and the cultivation of an American elm species.The “Jefferson” elm became one of the culti-vars that the Park Service uses to keep theNational Mall lined with large shade trees.

Two rivers run through the nation’s capital,and Wester as boy and man spent time onboth. He remembered an Anacostia River withmarshes full of wild rice and a Potomac Riverwith hundreds of acres of underwater grasses.According to Stephen Syphax who workedwith him on both rivers, Wester spent yearsgrowing test plots of wild rice in hopes ofrestoring the Anacostia marshes of his youth.Then he went to work on the underwatergrasses of the Potomac.

He carried his passions for these rivers intoretirement. By the spring of 1980 he’d beenofficially retired for three years when he startedfloating cages of hydrilla in the Potomac.

The monster weed that invaded the PotomacRiver never went away, but over time hydrillabecame hated less, perhaps even loved a little.

Fishermen came to like it first, since theywere often catching fish near hydrilla beds. Birdlovers were seeing wading birds walk out onthe hydrilla mats where they’d start pecking atthe grass and at the fish that emerged alongthe edges. And scientists were getting high-visi-bility readings when they dropped their secchidisks, good evidence the beds were trappingfloating sediments and helping clear the water.

All of which brought some relief to scien-tists with the National Park Service who’dtaken a lot of heat for releasing this non-nativemarauder into the Potomac. “What actuallyhappened, essentially to my consternation, wasthat people like hydrilla,” says Richard Hammer-

schlag. “Hydrilla rapidly filled an ecological void.”Several native species have also reappeared

in that void, perhaps helped along by hydrilla.More evidence of that came two years agowhen Nancy Rybicki reported her findingsfrom an annual survey she’s been running since1985 for the U.S. Geological Service. Whiletwo non-natives, hydrilla and Eurasian water-milfoil, account for 60 to 90 percent of thegrass acreage in the upper tidal Potomac, theirdominance has decreased over time. As waterquality improved in the river, the coverage ofseveral native species, especially wild celery andcoontail, increased — slowly, but steadily.

Hydrilla in the Potomac never became thescourge it was in Florida where the campaignto kill it continues. The wide, flowing Potomac isnot a Florida canal or creek or lake that can beeasily covered over. “We have a different per-spective,” Rybicki says. “We lost our grasses, sowhen something came back we were excitedabout it.”

The hydrilla wars abated, but they neverended. Scientists may be pleased, but boatersand sailors and waterside homeowners arestill unhappy when hydrilla blocks them off thewater. “People are trying to spin it and make apositive out of it,” says Jamie Hamilton whoowns a dock-building company, “but I don’t seeit.” Watching kids swimming through hydrilla,he even wonders whether someone coulddrown in the stuff.

Living with hydrilla means mowing it, soHamilton also owns a grass-mowing boat now,one of several along the river. In quiet shore-line coves from Dyke Marsh down past MountVernon and Mason Neck, marine contractorswill fire up heavy, clunky mower boats thissummer and begin chomping channels through

the thick hydrilla mats. The dead, smelly grasseswill probably end up in a landfill.

Fishermen will motor out through thesecleared-out channels. In waters where HoraceWester once used the wrong plants to restorea barren river, they will drop anchor along theedge of some large hydrilla beds. And therethey will start catching fish.

— fincham@mdsg.umd.edu

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