VWR — 1

The VirginiaWetlands ReportThe VirginiaWetlands Report

Summer 2002Vol. 17, No. 2

Phragmites australis (Reed Grass)Bane or Beneficence?

By Kirk Havens

P hragmites australis, also known as Reed Grass, has received con-

siderable attention in the last decade.Discussion on the value and functionof Phragmites has resulted in muchdebate regarding the merits of the plant.Some believe it is the next scourge ofthe planet - steadily overrunning anddevouring other plant communities as itmarches across the landscape. Othersconsider it a beautiful component ofthe landscape and photograph andpaint its feathery plume head as itwaves back and forth along theshoreline. In fact, a Phragmitespatch was a featured photographrecently in Southern Living Maga-zine. Some people are concernedabout its fire risk while others en-courage its growth as a privacyfence. Some research has reported itas having only limited value in re-gard to fish habitat (Hellings andGallagher 1992; Meyer et al. 2001)while other research suggests thatits value to fish is no different thanother plants (Warren et al 2001).Most reports agree that it has highvalue in stabilizing eroding banksand there is general agreement thatwhere it displaces diverse habitatsor habitats of threatened or endan-gered species it is undesirable. It hasalso become a serious concern in therestoration of wetlands and the con-struction of compensatory wetlandmitigation sites. Resource managersattempting to offset the loss of wetlandfunctions from destruction of natural

wetlands due to development activities,often require the construction of newwetlands. Phragmites colonization ofthese constructed sites may result in anet loss of function and a step backfrom the national policy of “no netloss” of wetlands (Havens et al. 2002).

Phragmites is a cosmopolitan plantfound throughout the world. It is anaggressive colonizer of disturbed sites,

particularly marsh sites with disruptedhydrology (Chambers et al. 2002), andis rapidly gaining ground in NorthAmerica displacing species such asSpartina cynosuriodes, Zizaniaaquatica and Spartina patens.Phragmites is considered native to

North America and was probably aminor component of the wetland plantcommunity in the past. P. australis hasbeen found in archeological sites in thewest and peat cores in the east. Stemsof P. australis, used as cigarettes, werefound in Arizona at the Red Bow CliffDwellings dating to 1325-1400 A.D.(Adams 1990). Phragmites was used inthe construction of mats in Anasazi

communities in Colorado dating to880-900 A.D. (Breternitz et al. 1986).In the past phragmites had manyuses including arrow shafts, food,cigarettes, and thatch for shelterand is still valued in Europe andAsia today.

Phragmites was first recordedin New England in colonial timesand its rapid increase in populationbecame a concern with resourcemanagers in Virginia about 40-50years ago (Silberhorn 1991). Theincrease in Phragmites promptedmuch discussion regarding thepossibility of a recent introductionof a more aggressive, nonnativegenotype. Saltonstall (2002) re-cently reported the existence ofnative North American Phragmitesand an introduced EuropeanPhragmites.The plant can survive in most wet

habitats. Its rapid vegetative propaga-tion and its ability to suppress otherplants by shading and litter mat forma-tion (Haslam 1973, Windham andLathrop 1999) gives Phragmites a dis-tinct advantage over other species. A

Phragmites australis, also known as Reed Grass.

2 — VWR

The Virginia Wetlands Report is aquarterly publication of the WetlandsProgram at the Virginia Institute ofMarine Science of the College ofWilliam and Mary. Subscriptions areavailable without charge upon writtenrequest to: Wetlands Program, VirginiaInstitute of Marine Science, P.O. Box1346, Gloucester Pt, VA 23062 USA.Address corrections requested.

Program Director: Dr. Carl HershnerHead, Wetlands Advisory Program: Thomas A. Barnard, Jr.Produced by: VIMS Publication Center

In this Issue:Phragmites australis (Reed Grass)Bane or Beneficence? ........................ 1Hellgrammites and Their Relatives .... 3Impacts of Sea Level Rise Studiedin Pamunkey River Marshes ............. 4GPS Technology Lends Supportto the Marsh Project ......................... 5Book Review ..................................... 6Worldwide Shrimp Farming andMangrove Wetland Losses:Are the Two Irrevocably Linked? ...... 7

This report was funded, in part,by the Virginia Institute ofMarine Science and by theVirginia Coastal ResourcesManagement Program of the Depart-ment of Environmental Quality throughGrant #NA97OZ0181-01 of the NationalOceanic and Atmospheric Administration,Office of Ocean and Coastal Resources Man-agement, under the Coastal Zone Manage-ment Act, as amended.

The views expressed herein are those of theauthors and do not necessarily reflect theviews of NOAA or any of its subagencies orDEQ.

Printed on recycled paper

single plant can spread over 1/8 acre in2 years (Fanshawe 1972). Once estab-lished it is extremely difficult to eradi-cate. The effectiveness of numerouseradication or control methods such asherbicides, flooding, burning, biologicalcontrol, and discing have been re-searched in recent times with mixedresults (Marks et al. 1994). The mostcommonly employed and effective con-trol method at present is chemical herbi-cide treatment used in combination withperiodic burning.

In Europe, deforestation oflakeshore woods in the Bronze Age andRoman period is believed to have pro-moted expansion of Phragmites (Rösch1987). In more recent times, these areashave been re-colonized by bushes andtrees resulting in a reduction ofPhragmites (Ostendorp 1989). This isencouraging news for those areaswhere woody species can be allowed togrow. Over time, trees and shrubs willreach heights that will allow them toshade out Phragmites.

Concern over the amount ofPhragmites in the Chesapeake Bay hasprompted the states of Virginia, Mary-land, and Pennsylvania, the District ofColumbia, and the U.S. EnvironmentalProtection Agency to include in theChesapeake Bay 2000 agreement a pro-vision to identify problem invasivespecies, and to develop and implementmanagement plans for such organisms.In May of this year, the ChesapeakeBay Program and Maryland Sea Grantconvened a workshop to develop re-gional species management strategiesand Phragmites was one of the speciesconsidered. A draft management planfor Phragmites australis is presentlybeing developed.

For more information onPhragmites, consider calling theRappahannock Phragmites ActionCommittee at (804) 443-1118 or visit thefollowing website www.vims.edu/ccrm/phragmites.

ReferencesAdams, K.R. 1990. Prehistoric reedgrass

(Phragmites) “cigarettes” with tobacco(Nicotiana) contents: A case study from RedBow Cliff Dwelling, Arizona. J. Ethnobiol.10: 123-139.

Breternitz, D.A., C.K. Robinson, and G.T.Gross. 1986. Dolores archaeological pro-gram: final synthetic report. U.S. Depart-

ment of the Interior, Bureau of Reclama-tion, Denver, Colorado.

Fanshawe, D.B. 1972. The biology of thereed - Phragmites mauritanus Kunth.Kirkia 8: 147-150.

Haslam, S.M. 1973. Some aspects of the lifehistory and autecology of Phragmites com-munis. Polish Archives of Hydrobiology:2079-2100.

Havens, K.J., H. Berquist, and W.I. Priest.Submitted. Phragmites expansion intoconstructed wetlands: Are we mortgagingour wetland future? Estuaries.

Marks, M., B. Lapin and J. Randall. 1994.Phragmites australis (P. communis):threats, management, and monitoring.Natural Areas Journal 14: 285-294.

Meyer, D.L., J.M. Johnson, and J. Gill. 2001.Comparison of nekton use of Phragmitesaustralis and Spartina alterniflora marshesin the Chesapeake Bay, USA. Marine Ecol-ogy Progress Series 209: 71-84.

Ostendorp, W. 1989. “Die-back” of reeds inEurope - a critical review of literature.Aquatic Botany 35: 5-26.

Rosch, M. 1987. Der Mensch alslandschaftspragender Faktor im westlichenBodenseegebiet seit dem spaten Atlantikum.Eiszeitalter Gegenwart 37: 19-29.

Saltonstall, K. 2002. Kryptic invasion bynon-native genotypes of the common reed,Phragmites australis, into North America.Proc. Nat. Acad. Sci. 99: 2445-2449.

Silberhorn, G. 1991. Reed grass Phragmites.Technical Report, wetland flora. WetlandsProgram, College of William and Mary,School of Marine Science, Virginia Instituteof Marine Science, 2 pp.

Warren, R.S., P.E. Fell, J.L. Grimsby, E.L.Buck, G.C. Rilling and R. A Fertik. 2001.Rates, patterns, and impacts of Phragmitesaustralis expansion and effects of experi-mental Phragmites control on vegetation,macroinvertebrates, and fish within tide-lands of the Lower Connecticut River.Estuaries 24: 90-107.

Windham, L. and R. Lathrop. 1999. Effectsof Phragmites australis (common reed)invasion on above-ground biomass and soilproperties in brackish tidal marsh of theMullica River, New Jersey. Estuaries 22:927-935.

Roasted Phragmites Rhizomes12 Phragmites rhizomes (6-8" long)Wash thoroughly, bake in oven at 350degree F for 25 - 30 minutes. Tastes like baked potato jackets.

Phragmites Gruel1/2 cup seeds of Phragmites2 cups boiling waterCollect a dozen or so seed heads.Remove the seeds and crush. Add toboiling water. Cover and cook slowlyuntil a thin red-colored gruel is formed.Cool and eat. Milk and maple syrupcompliment the dish.

For those daring souls out there, here are a couple of Phragmites recipes:

VWR — 3

Hellgrammites and Their RelativesRebecca Jo Thomas

Wetland Denizens!!!

"""

E ver go fishing using hellgrammites for bait? Hellgram-mites, the aquatic larval form of the dobsonfly (Coryda-

lidae corydalus), are most often found under rocks in cleanfast-moving streams. Their large size, up to 3.5 inches, andtheir large pinchersmake them interest-ing to catch and thatis why purchasingthem at a bait shopcan be quite expen-sive. However, theycome highly recom-mended by trout andbass fishermen alike.

Unlike their adult form, which has an average 7 day lifespan, hellgrammites can live up to 5 years before they crawl

out of the water to dig a pupal cham-ber in the mud. From there theyemerge into large flying insects witha 5-inch wingspan. Maledobsonflys have large pincher likemandibles used only for graspingthe female during copulation. Oncemating has occurred, the females willlay their eggs on rocks or plants thatoverhang the stream. When theyhatch, the larvae fall into the streamto consume small aquatic organismssuch as mosquito larva and beginthe cycle all over again.

A close relative of the dobsonflyis the fishfly (Corydalidaechauliodes). Unlike the hellgram-

mite, the larva of the fishfly is smaller and prefers the habitatat the bottom of a shallow pond or a pool in a stream, usuallyunder leaf litter, instead of stream riffles. To breath in thisenvironment, the fishflylarva uses respiratory tubesto obtain oxygen from theair in addition to gills.Specimens of this organismhave been collected locally,from the Hill Marsh regionof the Pamunkey River. Thisinsect experiences the samelife cycle as the dobsonflywith the larva living for 2 to

3 years and the adultsurviving only a matter ofdays. The adult, like itsoffspring, is smaller thanthe dobsonfly and it doesnot possess the largemandibles.

More distant cousins of the dobsonfly include two com-pletely terrestrial insects; the antlion and the lacewing. Adultantlions (Myrmeleontidae) are long-winged and slender-bod-ied, similar to damselflies. They lay their eggs in sand andupon hatching the larva may dig a pit in which it sits and waitsfor unsuspecting ants (or other insects) to fall into and be-

come food. In somecases, the other insectthat falls into the pit isanother adult antliontrying to lay its eggs.

All of the adultforms of the insectsdiscussed above arefairly hard to find be-cause they hide underleaves in the day andonly fly at night. They

are however somewhat attracted to lights at night and this iswhere the last cousin, the lacewing (Chrysopidae), is mostcommon. These insects are much smaller than the others,reaching about 0.5 inches in length. Their larvae are voraciouscarnivores and are sometimes called aphid lions because theirfavorite food isaphids. An indi-vidual lacewing larvacan eat 25 to 30aphids a day. Theseinsects are oftenreleased in agricul-tural areas as bio-logical control foraphids.

This is one of thetraits that group all of these insects together, their desire toprey on other insects. And, it just so happens that the insectsthey find the tastiest are ones that humans would prefer to dowithout. The species with aquatic larvae consume mosqui-toes, antlions love ants, and lacewings devour aphids. Justone of nature’s little perks.

Hellgrammite

Dobsonfly

Fishfly

Fishfly larvae

Antlion

Lacewing

4 — VWR

Impacts of Sea Level Rise Studied inPamunkey River Marshes

Carl Hershner

Continued on next page

V irginia’s Pamunkey and MattaponiRivers are home to some of the

largest pristine tidal freshwater marshesin the nation. The largest of these wet-lands are found in the bends of the tworivers just upstream of their confluenceat West Point. The marshes are highlyvalued as habitat for waterfowl, fish,and an amazing diversity of plants. Thetidal freshwater plant community isamong the most productive naturalcommunities known, with plant biomassproduction equivalent to the most in-tensive agricultural efforts. The marshplant communities are also renownedfor their aesthetic appeal, with a varietyof blooms and seed heads that changewith the seasons.

Several years ago, some of the own-ers of the marshes in the Pamunkey and

Mattaponi systems noticed a growingchange in the character of the vegeta-tion. Where large stands of giantcordgrass (Spartina cynosuroides)used to dominate, arrow arum(Peltandra virginica) was now themost common plant. The change wasparticularly noticeable in the fall whenmigrating waterfowl moved through themarshes. Where the marsh surface hadonce been screened by the dead stand-ing stems of giant cordgrass, the marshnow looked like a giant mud flat. Arrowarum leaves nothing above groundwhen it dies back in the fall.

Puzzled about thecauses and conse-quences of this change,the marsh owners joinedtogether under the lead-ership of Sture Olsson tofund the VIMS WetlandsProgram to research theissue.

The Wetlands Pro-gram scientists hypoth-esized that rising sealevel, potentially com-bined with local subsidence, was mak-ing it impossible for the marshes toaccumulate surface material fastenough to precisely maintain theirposition in the intertidal zone. Thiswould explain the transition from aplant community dominated by giant

cordgrass toone dominatedby arrow arum.

Research-ers had twoprimary ques-tions:

1. Whatwould be theecological sig-nificance of thechange inmarsh charac-ter?

2. Couldanything bedone to main-

tain or restore the original plant commu-nity structure?

The resulting project was designedto accomplish several things:

1. Document the differences be-tween giant cordgrass and arrow arumcommunities;

2. Evaluate several methods ofraising the marsh surface incrementallyto keep pace with sea level rise; and

3. Assess the potential for unin-tended expansion of the invasive com-mon reed grass (Phragmites australis).

The research project was designedto last at least four years, and to in-

volve intensive seasonal sampling atmultiple sites in Lee and Hill marsheson the Pamunkey River. As part of theexperimental design, a small hydraulicdredge specially designed to spray thedredged material was brought to themarshes. Wetlands Program research-ers obtained dredging permits in orderto conduct three small tests of the im-pacts of spraying dredged material ontothe marsh surface. This is a methodthat was developed in the Louisianamarshes for disposal of material duringmaintenance of access channels for oilproduction facilities. Spray dredgingwas specifically developed to add thinlayers of material to a marsh withoutdestroying existing vegetative commu-nities. The method has not been previ-ously used in the Chesapeake Bay.

In the current project, researcherswanted to determine if spray dredgingcould be used to raise elevations on themarsh sufficient to reestablish preferredvegetative communities. They alsowanted to evaluate the method forbroader use as a disposal option forselected dredging projects. A finalquestion was whether elevation in-creases could be controlled wellenough to prevent creation of suitablehabitat for Phragmites.

The project has been underway foralmost two years. Spray dredging wasconducted last summer, and both thefollow up studies and the basic ecologi-cal investigations have been underwaysince that time. Although all results are

Spray dredging in the Pamunkey River.

Location of spray dredge sites on Pamunkey River.

VWR — 5

G i SGeographicInformationSystem

GPS Technology Lends Support to theMarsh Project

Marcia R. Berman and Harry Berquist

Y ou learned about various compo-nents of the Marsh Project in Carl

Hershner’s article on page 4. GlobalPositioning System (GPS) technologyplayed an important technical role inseveral project components. This ar-ticle will summarize a few of them.

The ecology of tidal freshwatermarshes like those being studied in theMarsh Project is in part dependentupon the relationship of the surfaceelevation of the marsh relative to meansea level. If the marsh surface is unableto keep up with rising sea level theecology of the marsh will shift towardsfloral and faunal communities morereflective of shallow open water envi-ronments. As noted in the article byHershner, these marshes are exhibitingsigns of change and there is specula-tion that the marsh is subsiding, or atleast unable to keep pace with sea levelrise. The project explores the use of atechnique known as spray dredging toslowly raise the elevation of the marshsurface with the hope of restoring andmaintaining the higher marsh commu-nity. This is a technique that has beenused in Louisiana marshes undergoingsimilar environmental stress.

To evaluate the success of thespray dredging very detailed surveysof the marsh surface were required be-fore and after the dredging operation.Since anticipated changes would bevery small, a technique that could mea-

sure very slight elevation changes overtime was required. To accomplish this aGPS survey using dual frequency, car-rier phase measurements and Real TimeKinematic (RTK) positioning was em-ployed. Carrier phase measurementsprovide accuracy at the centimeterlevel. RTK surveys use a radio linkbetween the base station receiver andthe roving receiver so corrections aremade as the points are logged in thefield. In this project a base stationreceiver was established near the marshsites. The rover receiver, or unit on themarshes occupied multiple locations onthe marsh surface where the dredgespraying would be deposited as spoil.Approximately 80 points were mea-sured (x,y,z) at each spoil site. Theresulting coordinates in the form of adelimited text file were used to generatethe marsh surface topography in ErdasImagine software. Vegetation mappingof invasive species is also a componentof the Marsh Project. Phragmites aus-tralis has colonized these marshes andmay be out-competing native species.It is possible to evaluate the rate atwhich Phragmites can spread throughthese systems by accurately measuringthe distribution of the population overtime. Over large areas remote sensingtechniques are the most desirable op-tion for mapping Phragmites. How-ever, this technique requires extensiveground-truth investigations or ad-

vanced identification of trainingsamples collected during field visits.The Marsh Project has provided theopportunity to do both. GPS was usedto map the distribution of Phragmitesusing Trimble handheld GeoExplorers.The perimeter of Phragmites patcheswas walked and GPS data (x,y) werelogged continuously by the field opera-tor. The results provide a baseline fromwhich future measurements at thesesites can be compared to determine therate at which the species is spreading.At the same time, GPS located sites inthe field can be combined with ortho-rectified images of the area to identifythe specific signature properties ofPhragmites patches. Since the vegeta-tion make-up of these patches isknown, we can apply the same signa-ture properties [evaluated using imageprocessing software (Erdas)] to othersites.

This study has presented a veryexciting opportunity for VIMS-CCRMto combine accepted wetlands fieldresearch techniques with the data man-agement benefits of Geographic Infor-mation Systems (GIS) and GPStechnologies. By combining scientificinquiry and the latest in “high tech”electronic tools, researchers can ad-dress more complex questions withgreater confidence in their results. Wewill keep you informed as the studycontinues through the next two years.

very preliminary at this time, severalobservations can already be drawnfrom the effort.

First, spray dredging appears to bea potentially useful method of dredgedmaterial disposal. The initial findingson the three tests plots suggest the

marsh vegetation was able to withstandthe slurry application, and growthrough the accumulated material. Animportant caveat to this observation, isthat the material used in the Pamunkeymarsh study was very fine silt and mud.Heavier material such as sand or dense

clay may have more significant impacts.Second, spray dredging using fine

silt and mud from marsh creeks is not aparticularly effective method of increas-ing marsh surface elevation. Based oncalculations of material accumulation

Continued on page 8

6 — VWR

-BOOK REVIEW-

Wetlands ExplainedBy William M. Lewis, Jr.

Review by Walter I. Priest. Jr.

This book could easily be called Wetlands for Dummies.But, actually, it is much more than that. On a sliding scale itlies somewhere between the Corps’ 1987 Manual and Mitschand Gosselink’s Wetlands. It goes a long way towards ex-plaining many of the intricacies and nuances of wetland iden-tification and delineation.

The author, William M. Lewis, Jr., has unique qualificationsfor this task. He is Professor and Director of the Center forLimnology at the Cooperative Institute for Research in Envi-ronmental Sciences, University of Colorado, Boulder. He hasserved as a member of the National Research Council’s WaterScience and Technology Board and as Chair of the NRC Wet-lands Characterization Committee and as President of theAmerican Society Of Limnology and Oceanography.

Throughout, the author makes very effective use of analo-gies to make complex issues more understandable to the aver-age person or less than erudite wetlands scientists. Theseanalogies are very often humorous, but a dry humor that canbe as thought provoking and insightful as comical. They alsogo a long way towards demystifying wetlands regulations andscience. The author also avoids jargon wherever possible andrelies on common sense lay terminology.

The book begins with a short synopsis of the early wet-lands legislation and pretty much how we got to where we areprogrammatically. I was around for much of what is detailedand it all rings pretty true. It is short and succinct with littleembellishment. Included is a discussion of the national policyof “no net loss” which in reality seems to be “slow net loss.”It goes on to describe the various definitions of wetlands andhow these influenced the development of current regulations.In the next chapter Dr. Lewis provides an insightful discussionon the relationship between wetland functions and values.

The next three chapters each tackle one of the three param-eters of wetland delineation; hydrology, soils and vegetation.Again the humorous analogies play an important role as ve-hicles for the interpretation of the realities of the triumvirate ofwetlands. He often uses these to critique critical junctures inwetlands evidence to show the logic or the absence thereof.While spending a considerable amount of time discussing soilsaturation, growing season, and soil temperature as they re-late to wetland processes, he completely avoids the emergingparadigm that many wetlands, especially in the Southeast,never see temperatures cold enough to shut down biological

activities. One might expect the author to at least mention theissue given the copyright year of the book is 2001.

Throughout he argues that the most important, thoughintractable, parameter is wetland hydrology. Yet, becausethese data are the hardest to obtain and both hydrophyticvegetation and hydric soils are reflections of the hydrology, hefeels that it is acceptable to be able to infer wetlands hydrol-ogy from one or both of the other parameters, a la the 1989Manual. Some will agree with his position. He refers to theseas the “pragmatists,” those who are more willing to acceptrealities of life in the real world than the “literalists” who insiston conclusive evidence of all three parameters. This sets aphilosophical stage for a debate over the use of “risk analysis”in wetlands delineation. He feels it is better to err on the sideof increased inclusiveness that can be adjusted through pro-grammatic amendments as experience dictates. This is a betterrisk for the resource than the “literalist” approach, which mightexclude marginally identifiable areas through rigorous eviden-tiary requirements. The problem being that it is easier to relin-quish authority over non-wetland areas than to recoup theresource lost to the “literalist” approach.

Finally, a parting shot, on page 37 the author unequivocallystates, “Water, in the form of particular kinds of hydrologicconditions, is the specific cause of wetlands.” Yet on page 132he states, “there is more than a speck of uncertainty in thenotion that wetlands can be replaced functionally, even if thehydrologic conditions for the existence of a wetland are pro-vided with certainty.” These statements on their face appear tobe contradictory. On the one hand, he states that you cannothave a wetland without water while on the other hand he isstating that, even though you have water, you might not havea wetland after all. Well, to my way of thinking if you haveunder the right conditions you have or eventually will have awetland.

In summary, this book is exceptionally well written, emi-nently readable and technically sound. What makes this bookso attractive is the mix of homespun humor and front porchphilosophy that the author uses to explain complex and ab-stract wetlands concepts. Furthermore, it is done in such anengaging manner that one wants to keep reading. I whole-heartedly recommend this book to anyone who thinks theyknow a lot or would like to know more about wetlands science,policy and politics.

Editor’s Note:Please help us by returning the enclosed survey. If you prefer,you can fill it out online at: www.vims.edu/ccrm/survey.htmlThank you!

VWR — 7

aried & ersatile Wetlands

Worldwide Shrimp Farming andMangrove Wetland Losses:

Are the Two Irrevocably Linked?Pamela Mason

O ne of the most contentious is- sues today regarding the use of

wetland resources globally, is the con-version of mangroves and other shal-low water habitats into ponds forshrimp farming. Historically shrimpfarming was very labor intensive andperformed on a small scale. However,the ever increasing demand and tech-nological advances in production haveresulted in the dramatic conversion ofthe coastline of much of southeastAsia, parts of Central America andother areas into shrimp farms.

Mangroves are the intertidalwetlands of tropical coastlines.Functioning similarly toVirginia’s tidal wetlands, man-groves provide nursery area forcoastal fisheries, detritus to sup-port coastal food-webs, protec-tion from coastal erosion andstorms, and maintenance of wa-ter quality. The mangrove for-ests support many traditionaluses including harvest of fishand wood products. And whilethe human activities which ad-versely impact mangroves arenot limited to conversion foraquaculture (harvest for wood pulp,and charcoal production being twoother common activities), conversionfor ponds usually results in a loss of allthe natural ecological functions of themangrove forest.

The conversion of existing, or previ-ously timbered mangroves to shrimpponds has occurred along the coast-lines of many tropical and subtropicalnations. The greatest losses have oc-curred in those nations with the highestshrimp production. Thailand, number

one in worldwide production, has lostan estimated 50 percent of its man-groves. Losses in other southeastAsian countries typically exceed 25percent (The World of Mangroves).Ecuador, the second largest producer of

cultured shrimp, lost 162 square miles(20%) during a period of 22 years(Nixon, 1996). Beyond the conversionof coastal habitats into ponds, the in-tensive shrimp farms tax the assimilationcapacity of the remaining mangrovesand surrounding coastal waters andrequire large scale wild fish harvest inorder to produce shrimp food.

The idea of shrimp farming isn’tnew. Shrimp have been raised in pondsin Southeast Asia for centuries. Fisher-

men would take advantage of the natu-ral movement of shrimp from open wa-ters to coastal nurseries to capture theshrimp into ponds and hold the shrimpuntil harvest. Shrimp farms are classi-fied into four categories: traditional,extensive, semi-intensive and inten-sive, characterized by increasing stock-ing rates with corresponding feed andwater management activities. Duringthe 1970’s, the growing availability ofseed shrimp and formulated feeds,along with active government and pri-

vate sector support, promptedthe development of intensiveshrimp farms. (Primavera, 1994).With the start-up of the largefarms, the contribution of cul-tured shrimp to the total markethad risen from about 6% in 1970to 26% by 1993. In Thailand,cultured shrimp make up about70 percent of the total produc-tion (TED case studies: Thailandshrimp farming)

As a result of the intensivefarming practices, individualponds are short-lived, becomingquickly polluted beyond use,prompting additional clearing for

new pond construction. Additionally,the high stocking rates have encour-aged the spread of several diseaseswhich have wiped out an entire yearsproduction. Both China and Taiwanexperienced an almost complete indus-try collapse in the 1980’s and early1990’s.

Many factions, including someprogressive shrimp farmers who nowrecognize the critical role of water qual-ity in sustainable shrimp farming, are

Continued on next page

Crevette

Shrimp pond

8 — VWR

Calendar of Upcoming Events

October 7-9, 2002 Wetlands 2002 “Restoring Impaired Wetlands and Other Waters.” Indianapolis, IN.See the Association of State Wetland Managers at www.aswm.org/meeting/2002am.htm

October 22-25, 2002 Fifth EPA Wetlands Workshop. Atlantic City, NJ.Contact Ralph Spagnolo at (215) 814-2718 or email spagnolo.ralph@epa..gov

April 13-16, 2003 Inaugural National Conference on Coastal and Estuarine Habitat Restoration.Hyatt Regency Inner Harbor. Baltimore, MD. Abstract deadline is 9/13/02.Contact Heather Bradley at (703)524-0248 or email hbradley@estuaries.org

June 8-13, 2003 Society of Wetland Scientists 24th Annual Meeting, New Orleans.Changing Landscapes and Interdisciplinary Challenges.Contact Lisa Gandy at (501) 225-1552 or gandylc@swbell.net

July 13-17, 2003 Coastal Zone 03. Coastal Zone Management Through Time. Baltimore, MD.Deadline for abstracts is 9/16/02. Contact Jan Kucklick at (843) 740-1279 oremail Jan.Kucklick@noaa.gov

looking for solutions to sustainableproduction. Options range from legisla-tive protections for mangroves, to bet-ter management of effluent, to apolyculture of mangroves and shrimpoccurring in the same landscape, andother forms of crop rotation. Someefforts are underway to re-forest someof the mangroves, but this process,while promising, is new and untested(Nixon, 1996; Primavera, 1994). If thismore balanced approach to shrimpfarming takes hold, the practice maycontinue without the wholesale loss ofmangrove wetlands.

References:Nixon, Will. 1996. Rainforest shrimp.

MotherJones emagazine. http://www.motherjones.com/mother_jones/MA96/nixon.html

Primavera, J. H. 1994. Shrimp farming in theAsia-Pacific: environmental and trade issuesand regional cooperation. Presented at theNautilus Institute Workshop on trade andEnvironment in Asia-Pacific: Prospects forRegional Cooperation, September 1994,Honolulu HI. http://www.nautilus.org/pa-pers/enviro/trade/shrimp.html.

TED case studies: Thailand shrimp farming.http://www.american.edu/TED/THAISHMP.HTM

The World of Mangroves: Mangrove-friendlyshrimp culture. Http://www.mangroveweb.net/html/mangrov.htm

Worldwide Shrimp Farmingcontinued from page 7

using high accuracy GPS equipment,the amount of material successfullyplaced on the marsh surface was verymodest, given the amount of materialoriginally excavated. The material avail-able in the marsh creeks is so finegrained, that it does not settle out ofthe spray runoff on the marsh surfacequickly enough to accumulate.

Third, there are some apparent dif-ferences between the three marsh com-munities being intensively studied.Although data is still being collectedand analyzed, initial findings suggestthat bird and insect communities dovary between arrow arum, giantcordgrass, and Phragmites. If continu-ing work confirms this initial observa-tion, the slow transition from one typeof vegetative community to anothermay indeed portendshifts in the ecologicalservices provided bythese systems.

Researchers arecurrently undertakinga number of new stud-ies, as well as continu-ing the basicecological monitoring.This summer anothereffort will be made toincrease elevations on

the marsh surface in a number of verysmall test plots. Methods will include:containment of dredged material inbiodegradable containment bags; cre-ation of stilling ponds on the marshsurface using bio-logs (coconut fiberlandscaping logs); and addition ofwood chip layers to the marsh surface.

None of the methods of increasingmarsh elevations is seen as a panaceafor the problem of disappearing tidalwetlands. There are simply not enoughmaterial or funding to address the entireproblem. The current project is movingus closer to understanding the conse-quences of the ongoing change. It isalso arming VIMS scientists with theinformation necessary to providesound advice on potential future man-agement options.

Block net used to capture fish moving out ofHill Marsh with the tide

Spray Dredgingcontinued from page 5