lSSN O912−7410

No．20 December1992．ヽ IJけ．ヾI∴ 「・■ 「＝J†J
J〃TE尺〃dTJO〃dエ⊥A片E EⅣW尺0〃〃E〃T CO〟〟JTrEE FO【／ⅣβArJOⅣ
p FoT Better Lake Mana9ement
This Newsletteris also availableinJapanese．

5TH GENERAL MEET］NG OFILEC SCIENT］FIC COMMLTTE

Menlbers oflLEC Scientific ComrTlittee have metin（May1991）werereported．1tincludedlLEC

snewrole

Otsu，Japan．forthe5thGeneralMeetingonJune22，24，as the official supporting foundation for the UNEP
1992．Fourteen members，3former Members and 6lnternationalEnvironmentalTechno10gy Centre，Shi−0bservers participated弓n the GeneralMeeting whichga，andlng・Bauer s report on the Earth Summit・

was heFd at Lake Biwa R6iearchlnstitute．

4．

StrategleSforIakeecosystemsbeyond2000

wasapproved as the theme of the 5th World Lake
1．Newofficersforthisterm（April1992toMarch1995）

Conferencewhichwi

be heldinStresa，ltaly．in May

1993．

Were elected．
Chairpe†SOn

T．KiraVice Chairpersons

R．A．Vollenweider
Sanga Sabhasri

SecretaけS．MatsuiReguIar Bureau Members

S．E．Joergensen
J．G．Tundisi

2．ThreeWorkingGroupswereorganized・Eachgroupfocusedupon（i）EnvironmentalEducation，（ii）Guide−
Line Books and（iii）Data Co ection，reSPeCtiveIy・
3．1LEC s activities since thelast GeneralMeeting

5．NewILEC／UNEPjoint proJeCtS for1992／93andbeyond were elaborated and the new direction was
discussed．
6．1LECs coaboration with GEMS／Water was dis−

CuSSed，Whichincludedthebuild−UPOfdatabasefor
socio−eCOnOmicintormation．
7．The meeting agreed that the 6th World Lake
Conferencewi

beheldinlbaraki（nearTokyo，Japan）

in1995and the7th World Lake Conference wi

beheldin Argentinain1997・

1

2． Ex−Of†icio Members

MEMBERS OF THE SCIENTIFrC

ProfessoT．SetsunanUniversity Japan

T・GodaCOMMITTEE，lLEC FOUNDAT10N

andViceDirectoTGenera10fILEC
Founda 0【（1992−1995）

M．Hashimoto

Preside【t，JapanOversea5Environm即talCoop−
1．Regular Members

eratFon Center

Tatuo Kira

D行ector，（Chairperso【）Lake B血a Rese即Chlnstitu†eandViceDirectorGeneralofILEC

Japa【Fo】【datjo【R．A．Vo】」enweider

EmeritusSeniorScientist．NationalCanada（Vice・Chairperso【）Water Research lnstitute

Sanga Sabhasri

Chairman，Executive Board．The ThaiFand（Vice−ChairpersonI

NationalResearch Councilof

UNCED and Simultaneous
Events at Rio 92

Thailand
N．B．Ayibote】eDirecto「．

Ghana

Wate「Re＄0UrCeS Researchlnsti−

The United Nations Conference on Environment andDeve10Pr71entWaSheldinRiodeJaneirobetween3−13

tute
R．de Bernardi

D行e￠tOr，−1叫

Fnstitutoltaliano dildrobio10gla（CNR）

A・T・J・Carcagno

MemberofArgentinelnstitLJtefor Argentina
Water Resources

S．E〉teeV

SpeciarRepresentativefortheEx− UNEP
ecutive Director

Jin X伯【g￠anDeputy Director，

China

Water EnvironmentaElnstitute．
Chinese Research Academy of
EnvFro【mentalSciences
S．［．Joergense〔ProIe＄さ0「．

De【mark

The RoyalDanish Schoolof
Pha「macy
S．KaulJointDirector，l【dialndianMinistryofEnviTOnmentar［dForests

C．H．D．Magadza

Di「ector．

Zimbabwe

University Lake Kariba Research
Station，UniversityofZimbabwe
S．Matsui

ProIes＄0「，（Secreta「y）

KyotoU【ive「叫M．MeybeckPro†e＄SOr．

〕【iversityofPierreetMarieC〕rie
J．SaIaanki

Profe5SOr，

Hung叩

BalatonLinno10glCaIResearch［n−June1992．

1LECwasregisteredattheUNCEDasanintemational
NGOandwasrepresentedbyProf．S．Matsuiandlng．C．
E・Bauer，Who attended many meetings，rOund tablediscussionsand ceremoniesas observersduringtheir
StaySinRio．DuringthefirstweekLOftheconferenceMr．
K・Yamazaki．Director−GeneraIofthelLEC Foundation，Prof．J．Tundisi（lLEC Scientific Committee）and Mr．
KawagucM（［LEC Secretariat）were alsoin Rio deJaneiro deve10Plng different activitie＄aS rePreSenta−
tivesoflLEC・Theydistributedsevera＝1undredprinted
COPleSOftwopaperspreparedbylLEC．Thefirst， ［World
Lakes and Re＄erVOirsin EnvironnlentalCrisis ，WaS
Written for the United Nations Earth SummitI92con＿tained an Agenda Proposalfor theirlmprovements ．
The second one was aleaflet on generalinformation
aboutthenew UNEPlnternat‡onarEnvironmentalTech−
no10gy Centre and supporting foundationsin Otsu
（lntemationalLakeEnvironmentCommittee）andOsaka（G10bat Environment Centre）
DuringJapan Day，Which was held onJune4to
highIightJapan sroleintheGlobalCommunity，aVariety
Of reports on Japan s Experiences of EnvironmentaI
Pollution andits Efforts for G10balEnvironment and
DeveIopment weregIVenincIudingonebyMr．Yamaza−kionlLECs activities．

StituteJ．G．Tundisi

P「ofessor，

UniversiけOfS孟O Pau10
R．G．WetzelPro†es＄Or，BrazillLEC s Fund Raising Activities

The Univer＄ityofAlabama
W．D．Williams

Prolessor．
U【iversityofAdel占ide

lLEC is a public foundation whose activities are
funded to a considerabIe extent by theintere＄t from

CaPitaldonated bycompanies，grOuP＄andindividuaIs．

impact＄CaUSed by the release oftoxic substances to

Manysupportgroup＄havebeenstartedtohelpfinance

Surface waters．Lakes and reservoirs hoEdimportant

lLEC s ever widening activities．

freshwater ecosystems of the g10be，ln Which a great

ShigaBank，thelargestlocalbankinShigaPrefecture
WhereJLEC

s officeis10Cated，is participatingin the

Save Water Save Lakes

campaign by operating an

numberofspecies，includinghumanbeings，interactwith
eachother，Specialcaremustbetakenwhen releaslng
toxicantsintolakesandreservoirsbecauseoftheunIqueaccount through which depositors donate3％of the

PhysicaIandchemicaIcharacteristicsofconfinedwater・interest they receive on fixed term deposits toILEC，

Toxicsubstancesareretainedlon9erinbothwaterand

DepositorsnumberalreadycIosestofourteenthousands・

Sedimentsthaninf10WlngSurfacewater，Whichincreases

Another revenue raislng PrOJeCtis the lLEC Card ．

theriskofexposLJreOftoxicantsintermsofconcentra−

Thi＄isaninternationalcreditcardwithVisa，Mastercard

tionandduTationtobothaquaticorganismsandhuman＄

andJCBaffiLiationfromwhichlLEC receivesO．5％ofa

WhodependondrinkingwaterandfoodfromIakesand

transactions made with the card．The fiT St Card was

reSen／OlrS．

issuedinAugust1992，andbytheendofNovemberthe
number of card horders had risen to1500．
The highlight oflLEC
agalntheLake Aids summer activities was once

festival，Asin previousyearsthe

ThisGuidelineBookcoversbasicconceptsofaquatic
ecotoxicoJogy，CaSe Studie＄Of the Great Lakes andpractical experiences developed for toxic substancesmanagementintheRuhrRiverbasin．Germany，Afterthe

lLEC presence at the fe＄tivalwas considerabIe andintroduction the next three chapters introduce basic

donations co

COnCePtSforTeaderswho are notfamiliarwith ecotox−

ected on the day totaIed some570，000

Japanese yen（C．A．US＄4，400）．
TheUNEP／lETC（lnternationalEnvironmentTe（：hnol−

ico10gy．Chapter 2 describes generalprincip［es of
toXiCOlogy whiCh focuses on ecotoxicology on aquatic

OgyCentreofUnited NationsEnvironmentProgramme）

lifewithanernphasisontheunlqUeneSSOftheecosys−

OPenedthis autumn andlLEC has been appointedthe

tem ofIakes and reservoirs．Chapter3describes the

OfficialsupportingfoundationforUNEP／lETCinShiga・

movementoftoxicsubstancesthrough bioaccumuIation

The financialcommitrTIent tO rUn＄UCh an organization

anddealswiththeimportantchemicalfactorsinvoIvedin

SUCCeSSfu

yIS COnSiderable andlLECis seeking the

COOPeration ofcompaniesaffiliatedtothe KansaiEco−

bioconcentration and bioaccumu［ation．The ecologlCal
StruCtUreOfbiomagnificationisalsoemphasizedandthe

nomic Association，the Federation of Economic Orga−

Minamata andltai−itaidiseases are brieflyintroduced．

nization and10Calcompaniesin Shiga．1LECis also

Chapter4focuses on modeling oflake ecotoxicoIogy．

100kin9for contributions from ov寧rSeaS．Readers who

relatingtoxicantmovementinlakeecosystemsquantita−

WOuldlike to contribute should send donations toILEC

tivelysothatreaderscanunderstandbasicconceptsof

atthe address glVen On the back of this newsletter，

toxic managementin terms of mass balance．
The remainIng Chapters dealwith specific groupsof
toxicsubstances．Chapter5describesheavymetaland

GuideIine Book Vol．4

Otherinorganictoxicsubstances，inwhichthe sources．
movementandsinksofrepresentativeheavymetalsand
Otherinorganic substances areintroduced withimpor−

GuideIines of Lake ManagementVol．4：Toxic Sub−
StanCeSManagementinLakesandReservoirs，editedby

tantpointsfortheirmanagement，Chapter6describe
Organic pesticidesin aquatic environments−the Great

Saburo Matsui，Published by UNEP andlLEC．1992． LakesstLLdiesinwhichdetailedinformationonpo

utionfrom many prominent pesticidesisclearlysummarized

170pp・

The 4th volume of the Guidelines series on lakewith an emphasis on the importance of atmosphericmanagemententitled

ToxicSubstancesManagementin mlgrationofthosepesticidesoverentirelakes．Chapter

Lakes and Re＄erVOirs

was published bylLEC and

UNEPinJune1992．
ThefollowfngeXtraCtfromtheintroductorychapterof
the bookwritten bythe editorProfessorSaburo Matsui
OUtlines the scope of this parLicular edition．
Toxicmanagementoflakesandreservoirsisaimedat
the protection of human heaIth and aquaticIife from

7 describes other organic toxic substances with anovetview of various organic pollutants in terms of

SOurCe＄，StOrage，tranSPOrtation，uSe，fate，PrOPerties，
andpreventionpoliciesarepresentedwithanemphasis
On COmmOn PrOblems faced by deve10Plng COuntries
With exampfes of PAHs．

Asian Wetland Symposium

ThesymposiumonAsianwetlandtowardwiseuseof
UPOnthese．Butwetlandsare beinglostand degraded
themwasheldfrom15to190ctober1992atLake Biwa
rapidlyin Asia，aSWelr asin otherregions，and many
ResearchInstitutelocatedin Otsu，Shiga on15th−17th
PeOPlearepay［ngthecost，SOmeWithanincreasedco＄t
and Kushiro Citizens CuIturalHa ，Kushiro City，Hok−
Oflivlng，and some with theirlives．
kaidoon19th．1tbroughttogether270participantsfrom
1f wetlands are to be managed sustainably，Part−
25countries．Thefive−daysymposiumwasorganizedby nerships are required on10Car，national，reg10naland
fiveJapanese governmentaland non−gOVernmental
intemationallevels．bringlng tOgether people from thebodies；Environment Agency，Hokkaido Prefectural
many disciplines required for an effective integrated
Government，ShigaPrefecturalGovernment，lLEC，Ram−approachto management．Attention needsto beglVen＄arCentreJapan，and RegionalPromotion Committee
to the conservation problems of both the wetland site
forthe Ramsar Kushiro Conference．The Ramsar Con−
itself，andthecatchmentbasinwhichprovidesthewater
Vention Bureau，ADB，lUCN，WWF，AWB，JWRB，Were upon which the wetland depends．
amOng CO−SPOnSOrS・
1frecognitionofthisneed，theAsianWetlandSympo−
Thereportonthissymposiumcontainmgrelatedlaws
Sium callsforurgentactionto betaken．specificallyln
and guidelineswi bepublished and distributedatthe
the fol10Wlng rTlaJOr areaS，tO maintain and wisely u＄e
1993Kushiro Meeting of the Ramsar Convention．
Asia s wetねnd resource＄．
Based upon presentations and discussions at four＄eSSions（ Wise UseofWetIandsand NecessaryLeg−
1． Awarene＄S
islations ， Management and Monitonng of Ramsar
Many Asian peoplelivein c［ose association withSites ， lnternationalCooperation on FinancIng and
Wetlands，Yettheywi onlysupportwetlandconserva−
Research and TouristicUseofWetlands ），Thefo ow−
tioniftheyunderstandfu］tythevalueofwetlandsand，ngreCOmmendationswereadoptedatthecloslngOfthe
the role that these can playln their dailyIives．To
SymPOSium．
addressthisproblem，SixmaJOrStePSShouldbetaken．
2．1nstitutionalCapacity and Training
Ifthecha engeofwiseuseistobemeteffectively，Recommendations（excerpt）
OUr SOCieties need to provide appropriate national
institutions with the capacity required．This certainIy
Wetlands are amongst the most vaIuable・naturar
ecosystemsin Asia，bringlng benefits to miIlions ofmeansincreasedfunding，buta（sotherequ［Sitenum−
ber of we‖−mOtivated，knowledgeable and skilled
PeOPleeachyear．Theseestuaries，f100d−Plains，fresh−
Staff，To this end，the fiveissues should be、析erited
Water marShes，rivers，lakes and peatIands pIay an
SPeCialattention．
intimatero［einourdailyIives，helpingtopurifyourwater
SUPPlleS，absorbfloodwaters，PrOVide muchofthefish
3．Wetland Monitorlng
We eat and support a rich diversity of species．Asia s
lfpublicawarenessandgoveTTlmentSuPPOrtaretOlarge population ha＄derived much ofits sustenanc
be hamessed effectively，and wetland con＄erVationfrom wetlands，andin the future wi continue to draw
effortsaretobedirectedatthehighestprIOrities，the4

StatuS and threats to wetland need to be rnonitored
finallytoensure adequateinvoIvementofNGOsand
C10Sefy．Toachievethis，fivemalOraCtionsshould be
COmmUnitygroupsinthedecision−makingprocesses．
taken．
8． Eco−Tourism
4．Consensus BuiIding
One mentioned of creating pubIic awarene！S Of
The wetland conservation cha‖enge needs to be
Wetlands，Of promoting scientific knowledge and of
taken up bya levels ofsociety．Governmentagen−generating revenueis to encourage ecosystem．Yet
Cies，NGOs，graSS−rOOtCOmmunitygroups，aCademic therej＄adangerthataninfluxoftouristsmayhavea
institutions andir［dustries，aIlneed tolOin forces．To
SeVereimpactonthewetland resourceand on10Ca（
facilitate theformation ofthis broad−based coaFition，
PeOPlelivlngtheTe．Tothisend，thefourissues need
to be addre＄＄ed．
the thTee aCt寺ons shouId be taken．
5．Policy and Legi＄lation
Many＄tate＄intheAsianreg10nhavenotdeveIoped
FinalIy，reCOgnlZlng the role pIayed by the Ramsar
Convention in conservation and wise use of wetland
national wetland policies and national conselvation
StrategleS，Which are urgentlyneeded・tO PrOVidethereSOUrく；eS，
ba＄isforlawsfortheconservationofwetlandsandfor
The Asian Wetland Symposium
theirwise use，Tothis end，thesixactionsshould betaken．
Ca sformore effectiveimplementation ofthe Con−
Vention andin pa「【icular；
6．lntemationalCoopeTationln the Asian reg10n，eXChange ofinformation，JOint（1）fordesignationofnewRamsarsitesinJapanand
reseach actions and assistance from one country to
OtherAsiancountries，andmoreeffectiveIeglSla−
another，also for10Calaction，are needed．Actionis
tive conservation and management mea＄ureS atalsoto befurtherdevelopedin bilateralcooperation
Site＄．
for the conservation of shaTed wetlands and their（2）forwiderapplicationofthewiseconcept，nOtably
CatChmentareas．Tothisend，thefouractionsshould
throughadoptionofnaturalwiseusepoIicieswith
be taken．
appropriateIegISlasi）e supporE，and
7．DeveropmentAssistanceandWetIandCon＄erVation（3）forbroaderadoptionofinitiativespromotinginter−
The thirEeen actions shouId be takenin order tonationalcooperationinthe field ofwetFand con−minimize theimpacts of deve10Pment aSSistance
SerVation，relathg to shared species，Shared
PrOJeCtS；tOincrease thelevels offund alIocatiorltO
Wetland systems and deve10Pment aSSistances．
environmentaIly−SOund proJeCtSir［Wetlands；and【 ■ヽ▼ヽ・

・−I■

′や与
‰、

ヽ−．1

∵j．一．．．㌦

炸㌣しマ
1訂

畏＝員叫1円ulNTECOLⅣlnternational Wetlands Conference
More thah850wet！and／eXPertS from56countries

lnteractions with Watersheds，Lakes and Riparian

gathered at the Ohio State Universityin the UnitedZonesNwhich was pre−Sided over by Professor S．E，States from September13 to18，1992，tO discuss

Joergen＄en．

Wetlandissues．ThiswasthelargestmeetirlgeVerheIdin
the world on wetlands and broughttOgetherscientists
from both developing and developed nations to seekcommon understanding of the world wetland systems
andtosetnewdirectionsforthe21stcentury．Morethan
500papers were presentedin14symposia and30
SeSSions and paneIs．1LEC was among conference
COntTibutors sponsored the session of Nwetlands：

Majorpointstocomeoutoftheconferenceincluded：＊ThefutureofwetIandshasbecomeaglobalissueinneedofgIobalinformationsharing，COOPeration，POli−
Cy Setting，and action；＊Althoughlessthan6％oftheworld sland surface手s

Wetland，these wetlands contribute a far greater
PerCentagetOtheworfd sovera biologrcalproductiv−

ity and water resource functions；5＊Wetlands are disappearlng at an a）armlngrate
throughouttheworld．ForexampleintheUnitedStatesalonewetlandsaredisappearIngatarateOf200，000to
400，000acrespe【yearandin spite oftheincreased
recognitionoftheimportanceofwetlandsaroundthe
WOrId，little progresshasbeen madein ha柑ngtheirdestruction；and＊WetIandsareveryimportantin providing biodiversity
and coastaland estuarine wetlands are seriou＄ly
threatened by gIoba［warmlng and subsequent sea−

Futuredirectionsforthe21stcenturylnClude．amongst
manyothers，COmPleteinventoriesfortheworld swet−
1ands and trainlng and educatjon for govemment offi−
Cials，landowners．englneerS，lawyersandbioIogists
Wetlandfunctionandvalueandtechniquesformanage−
ment．

There was an overa］lconsen＄uS at the meeting thatinternationalcooperationofthesortdemonstratedatthe
COnferenceprovidedanincreaseofoptimismforstem−
mlng future wetlnds10SS．

1evelrise．

LAKES OF THE WORLD

LAKE OF GUIERS（SENEGAL，WEST−AFRICA）

by Dr＄．F．X．Cogels／）．Y．Gac（Drstom，Daket，Senegal
LakeofGuiersistheonlylakeinSenegal・Located50 river．Thelake supports severalsma agnculturalin−Sta］lation，WhicharefoundaI（arounditsperiphery．1talso
kmfromtheAtlanticcoast（Iatitude16 10′N；Iongitude
PrOVideslOto15％ofthedrinkingwaterofDaker，the16008 W），itisanarrowcavity50km10ngand7kmwide，
situatedat2meters beIowsealeveL．Thelakeconstitute
CaPitaIcity（population2mi ion），througha250kmwater
main．An openaircanaIproJeCta owlngthetransferof
animportantfreshwaterreserveandisconnectedtothe
450 m‖iom m．
IowerSenegaEriverinastraightrinebytheTaouecanal・Since1985，theDiamadamhasmodifiedthehydroIo−
AsystemofsluicegatesalIowcontro10fwaterexchange
gy oflake of Guiers．Thi＄river dam，10Cated100km
between thelake and the river．
downstreamfromthelake，WaSbuilttopreventseawater
The configuration of thelake changes con＄iderably
infIowin thelower valley of the Senegalriver．The
through time and space，Underthe effects ofthe riverabsenceofreliefpreviousIya owedseawaterintrusion＄
inflows，Iossesthroughevaporationand pumplng．lnits
upto250kminland．Theriverwaterwouldthusbecome
averagestate，thelakehasadepthofl．5meters，anarea
brakish．1妻mitinigthedeve10PmentOfirrlgatedcultivatedof225km2and a volume of350mi ions m3．
land．Aseconddam（ManantailinMali），builttoreguIate
The first modifications aroundlake of Guiers date＄
fromthe1950 s．ThedammlngUPOfthenorthernreglOn thef100d＄．issituated1200kmupstream；ithasbeenin
USe Since1987．
and the closlng Of the southern and western outfEows
The ng10n ha＄a Sahelian climate：a ralny SeaSOn
madeitinto thelargest fresh water reservein thelasting2to3months，irreguIarpIuviometryof200−250
COuntry，beforethebuildingofthedamsontheSenega1

6

mrnperyear，anaVerageannUaltemperatureof28●cand The pHis＄tab（e，Varying frorT17．5to8．0（extreme
COnditionsexpected）・Theaverageconductivity，yearby
a10W Telative humidity（40％）．
year，is of280micros／m at25dc butthe variationis
importantaccordingtothestationandtheperiodofthe
The hydroIogy ofthelakeis complexand has beenyear・
drastically modified since1985：
Nitratelevelsare10W，Whilephosphoruslevelsarein−before1985，hydroIogyandlake swaterleveJwere
theorderof30kgr／m・Thestudyofnutrientshasyetto
dependentontheimportanceanddurationoftheannual
be undertaken．
river flood，Whichin tum was dependent on the pIリー
ViometTyOftheupperbasin，itseIflarge（ydeficitarysinc
Since1985，themoreconsiderablerenewmgoflake
1972・Underthe combined effectofinsuffjcientfiIllng，Waterbyriverinflowhascausedaspectaculardecreas
increased pumpingforirrigation，and ev色POration（2．25
ln mineニm peryer），thelevelofthelakein cerEainyearswent
ーalgalbloomshave beenobservedsince1989，With
beIowthethresholdIevelsbeIowwhichitsexp10itationis
high concentrations of Cyanophyceans（Anabaenaand
limited．ExtremecorIdition＄Were reaChedin1984whenthelake was almost completely dried up．
Mycrocy＄旺＄）．
−higher aquatic vegetationis deve10PIng．With an−Since1985．theeffectsoftheDiamadamhavebeen
invasion ofthesoutheTnIake reg10n byPistiastratiotes
Clearlydiscemible，WaterispermanentIyavaiIableinthe
andrapiddeveZopementTyphaaustralis．Otherspecies
river，thelakecan befi ed severaltimesperyear，its
thatwererareorabsentbefore1985arenowappear．ng
Waterlevels are more stabIe and higher，glVen aand rapidly proliferating．
【eduction ofagrlCulturaIpumplng．

−fishfaunaisdiversifyingandseemstobeadaptingto

the new hydrological conditions. The annual fishing
Theactualrateofuseofriverinf10WStOthelake（forirrigation and drinking waterproduction）is10W（about POtentialis estimated at1600tons．
7％）・On the other hand，the10SSeS are due majnlyto
We should also mention the appearance and rapid
evaporation（90％）・The problem of the quantitat事ve
deve10PmentOfintestinalschistomiasisupstreamofthemanagement ofthis SaheIian ecosy＄tem thus appears
Clearly．
Diama dam since1987．The spread of this disease
towardslake of Guiers，Where the mo‖uscthatacts as
Thephysicochemicalqualityofthewaterischaracte−intermediaryhostispresent，isinevitableintheshorlterm．
rjzed byyearlyevoIution ofthe mineralization of＄Olu−
TheDiamadamhashadrapjdandobviouseffectson
tions and the establishment of早Welldefined saIinity
the hydro10gy，Physico−Chemisty and hydrobio10gy Of
gradient fTOm nOrEh to south．The current totalminer−lake ofGuiers．The evoIution observedis howevertoo
alizationi＄OnaVerage270mg／l（7．7meq／l）．Through−recentfor a reliable diagnosis to be estabIished．
Out the year，OutSide of water replenshing periods
broughtbytheriverfIoods，COnCentrationoftheannual
ThelakeofGuiersaSahelainecosystemthatisfragfle
and very sensitive to environmentalmodification．1ts
Water COnCetration gradientis4．5currently．
lnextremeconditionsobservedduringdroughtyears，
importantasfuturesourceofwaterforthemostpopu−
before1985，Cho）oridesreachedlevealsof230mbq／I．
lated region of the country maks it necessary toimportantsoundandconcertedmanagementpractices
AverageyearIyconcentrationgradientoflakewaterwas
6．5then．

Sta「【ing now．

SeS＄10nS：

Forthcomlng COnference

1・Scientific basis for managlng eUtrOPhication
2，Waterquantityandqualityinlakesandre＄erVOirsfor human uses

stresa，93

3・Thefateandeffectsofin−1ake micropollutants

5thlnternationalConference on the Conservation and

4．Non−POint sources controlfor nutrientsManagement of Lake＄theme：StrategleS forlake ecosystems beyond2000

5．Acidrainandeffectsonaquaticecosystemsona

date：17−21May1993
Venue：Congress Centre，Pa＝azo deiCongressi，Stre−

6．Scientific findings and their utilization at socio−

Sa．1talyg10balscaleeconomic and administrativelevels forlake／
reseⅣOir management

organizers：lstitutoltaliano dildrobiologia（CNR）
lstituto diRicerca Su e Acque（CNR）

7．Lakes and environmentaleducat弓on
8．Citizen participation

1nternationalLake Environment Committee

language：Engli＄h（lLEC）

deadline for paper：31January1993

InternationalAssociation on Water Quality

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