Assessment of the ecological status of Danubian floodplains at Tulln (Lower Austria) based on the Odonata Habitat Index (OHI)

16 Pages·2003·1.4 MB·English

by  Schultz, H

Odonatologica32(4):355-370 December I,2003
Assessmentof theecologicalstatus ofDanubian
floodplainsatTulln(Lower Austria)
basedontheOdonataHabitatIndex(OHI)
H.Schultz¹,J.A.Waringer¹ andA.Chovanec²
'Instituteof EcologyandConservationBiology,University ofVienna, AlthanstraBe 14,
A-1090Vienna,Austria
2Federal EnvironmentAgency,SpittelauerLande5,A-1090Vienna,Austria
ReceivedOctober25,2002/Reviewed andAcceptedMarch21, 2003
Theecologicalstatusofwaterbodies situatedinaDanubianfloodplainsectionatTulin
(LowerAustria)wasassessed by adragonflysurvey usingthe“Odonata HabitatIndex”
(OHI)approachsuggestedbyCHOVANEC &WARINGER (2001,RegulatedRiv.Res.
Mngmt17:493-507).Theinvestigationwascarried outat 28standingwaterbodiesand2
referencesitessituateddirectlyattheDanube.Stretchesof100m shorelengthweremapped
andthe“RepresentativeSpectrumofOdonataSpecies”(SCHMIDT,1985,Odonatologica
14; 127-133)was recorded. Only autochthonous spp. wereused forthe assessment
procedure. Atotal of 11Zygopteraand 20 Anisopteraspp. wasrecorded,29 ofthem
autochthonous. Site-specificOdonata HabitatIndicesrangedfrom 1.72to3.67.TheOHI
oftheonlyreference sitewhere OdonataweredetecteddirectlyattheDanubewas 1.38.
ThemeanOHIforthewholefloodplainsectionwas2.79.Thesefiguresindicatearelatively
high level ofhabitat diversity. By comparingthis status quo withreference conditions
derived fromtheoverallhabitat situationbefore theregulationand from old species
inventories datingback totheI9"1century,thestatus oftheTulinfloodplainsectionwas
ranked asclassII(“goodecologicalstatus”)ina5-tieredclassification scheme.
INTRODUCTION
Thedynamicinteractionbetweenwaterandlandistheprincipal impetusthatcreated
floodplains and controlstheircharacteristic functionalprocesses (TOCKNER etal.,
2000),thereby maintainingtheecological integrityofriver-floodplain systems. Aspects
of lateralconnectivity are considered to beespecially indicativeofthisecological
integrity ofalluvialrivers (e.g.AMOROS&ROUX, 1988;BAYLEY, 1995;WARD
&STANFORD, 1995;WARD etal., 1999),andtherelevanceofbioindicatorgroups
has been comprehensively discussed (e.g. WARINGER-LOSCHENKOHL &
WARINGER,1990;SCHIEMER&WAIDBACHER, 1992).Withinthisframework.
356 H.Schultz,J.A.Waringer&A.Chovanec
dragonfliesplayanessentialrole(e.g.WARINGER,1989;CHWALA&WARINGER,
1996;WASSERMANN, 1999;CHOVANEC & WARINGER,2001;CHOVANEC
etal., 2002). Odonatahaveevolvedawiderangeofphysiological, morphological and
behaviouraladaptations, allowing themto colonisethewide rangeof loticandlentic
habitatstypically present infunctioning floodplain systems.Thisability makesthem
powerfulindicatorsforevaluating theecological qualityofland-waterecotones,habitat
heterogeneity (e. g.bank morphology andaquatic vegetation) and the hydrological
dynamics ofwater bodies(SCHMIDT, 1985;CORBET, 1993;SAMWAYS, 1993;
CHOVANEC &RAAB, 1997).
Theuseofdragonflies asbioindicatorsbenefitsfrom along traditionofecological
work on thisinsect groupwhich led to an advancedknowledge oftheirecological
needsandoffersmanyadvantages: Therelativelysmallnumberofdragonflyspecies is
mostly identifiablein the field,by photographs or by examining exuviae, thereby
matching the principles of conservation.In addition, therelatively long ontogenetic
development ofodonate species meets requirements for medium to long-term
monitoring,andtheirmigrationbehaviourenablesthemtorapidly colonizenewhabitats.
The aimof thepresent study was, therefore, touse the bioindicationpotential of
Odonataforthe study ofpoorly-investigated floodplain waterbodiessituatedwithin
theriverineforestsoftheDanubeatTulin(LowerAustria)andtoassess theecological
status ofthis Danubianfloodplain section by using the procedure suggested by
CHOVANEC & WARINGER(2001).
Fig.I. Mapofthestudy area, showingthe Danube,its tributaries (Perschling-Hochwasserkanal,GroBe
Tulin)andstandingwater bodieswithintheriverine forestsalongthe northernbank.Encircled numbers
indicatethesamplingsites.The upperrightinserthighlightsthepositionofthesamplingarea withinthe
bordersofAustria.
OdonataHabitat Index (OHI) 357
STUDY AREA
The Danube is2850 km longand,by this,the second largestriver inEurope. Itrises in theGerman
BlackForest,crossesacatchment ofapproximately805300km2 anddischargesinto the BlackSea. The
riverenters AustrianterritoryattheGermancityofPassau,transverses theFederal states ofUpperAustria,
LowerAustria andVienna and leaves Austria ashort distance upstream ofthe city ofBratislava. This
AustrianstretchoftheDanubeis352km longwhichisequivalentto 12.3%oftheDanube’s totallength.
AccordingtotheStrahler-systemthe AustrianDanubeis a9thorder stream (WIMMER& MOOG,
1994)with anaveragemeandischargeof2.000 m'/s.The flowregimeisprimarilyinfluenced by large
alpinetributaries,with highestwaterlevelsinlatespringandearlysummer.TheAustrianDanubecanbe
characterisedasrelativelysteep stretchwith anaverageslopeof0.44%candwith highcurrentvelocities
(2.0-2.65m/s1intheline ofmaximum velocityofflow).
Historically,theanthropogenicinfluence onthe Austrian stretch ofthe Danubemay be divided into
threephases:aftertheregulationinthe 19lhcentury(phase1),thefirstdamofanhydroelectricpowerplant
wasconstructedintheearly 1950s(phase2).Finally,uptonow(phase3),theAustrian Danubehas been
tranformedintoapower-generatingwaterwaywhere theformercontinuityoftheriver isnowinterrupted
bytendamsused forhydroelectricpurposes.Currently,the WachauandthesectionbetweenViennaand
the easternborder ofAustriaremaintheonly stretches oftheAustrian Danubewherethehydrological,
sedimentologicalandecologicalconditions ofanunobstructed,naturalriver still apply.
Ourstudy site(Fig.1)isinthe backwaterareaabovethehydroelectricpowerplantofGreifenstein and
nearthecityofTulin(altitude:180m;48°20’N, 16°04’E).Atthestudysite theDanubeisconfinedwithin
artificialbanksandpavedwith boulders;theriver isapproximately350mwide.Waterbacksupfromthe
damofthepowerplantand therefore themaximumsurface watervelocityis significantlyreduced when
comparedwith thesituationatthefree-flowingDanube;atthestudysite,themeanwatervelocityis 0.68
m/s1atbaseflow.Annual fluctuationsinwatertemperatureoftheDanubearehigh(0-21°C).Atbothsides
oftheDanube,manypools,ponds,cut-offsidearmsandflooded gravelpitsarelocatedwithintheriverine
forestsofthefloodplainwhich,inadditiontotworeferencesamplingstations directlyattheDanube, were
the focusofthepresentstudy.Mostwaterbodies investigatedinthepresent studyarepartofarestoration
project(“GieBgangGreifenstein”) whichtried toimprovethewater supplyby artificiallyconnecting
individualwaterbodiesandbyre-establishingriver-floodplaininteractions(cf.WIMMER& CHOVANEC,
1999). As the sites have been described in detail by SCHULTZ (2002),only abriefaccount on the
environmental parametersactingateach samplingsite isgiveninTableI.
MATERIALANDMETHODS
Theevaluation oftheecologicalintegrityofriver/floodplainsystemsisbasedonacomparisonbetween
thereferencecondition andthestatusquoofagivenarea.Thedegreeofdeviationfromtheformerindicates
theextentofhumanimpacts.AstheprocedurehasbeendescribedindetailbyCHOVANEC&WARINGER
(2001),onlyabriefaccountisgivenhere.
Beforeactualfieldworkstartsfieldexcursionswerecarriedoutinordertoselectrepresentativesampling
sitesreflectingtheproportionofdifferent habitattypes present inthestudy area.Aquantificationofthe
habitattypes wasmadeby measuringshoreline lengthsperhabitattypeby using officialmaps (scale=
1:25000).Samplingsitesrepresentingdifferent habitat types wereobserved occasionally atthesame
waterbody.Tomaintain ahighdegreeofcomparability,largerwaterbodiesweredividedintostretches of
100mshoreline length;smalleroneswereinvestigatedin total.
Field collections wereperformedinoptimalweatherconditions fordragonflies.Inorder tocoverall
phenologicalgroups (from early springspecies to late summer/autumn species) and to record the
“RepresentativeSpectrumofOdonataSpecies”(SCHMIDT, 1985)41fieldtripsbetween 25April2001
and30April2002wereperformed.Abundanceestimateswererankedwithinafiveclasssystem: 1:single;
358 H,Schultz,J.A.Waringer& A.Chovanec
TableI
Habitattemplatesactingatthe thirty samplingsites showninFig. 1.Foreachparameter,itsimpactatthe
givensiteisindicatedby anumeralrangingfrom0to3(0=negligible; 3=very highimportance)
Environmentalvariables
Water Reed Floating Open Riparian Open In- Tempo- Arti- Rip-rap
Site current belts leaves water trees & banks solation rary ficial
surface brush water water
1 i 0 1 3 2 1 3 0 3 1
2 0 3 1 3 2 0 3 0 0 0
3 3 1 0 0 2 0 2 0 2 2
4 1 3 1 2 1 0 3 0 0 1
5 0 1 3 3 2 1 3 0 0 0
6 3 3 1 0 I 1 2 0 0 0
7 0 3 3 3 0 0 3 0 0 0
8 0 0 0 3 1 2 3 0 3 0
9 0 3 2 3 2 0 3 0 0 0
10 0 3 1 2 3 0 2 0 0 0
11 0 2 0 0 2 0 2 0 0 0
12 0 3 0 0 3 0 2 0 0 0
13 0 3 1 0 3 1 1 2 0 0
14 1 1 2 3 2 0 3 0 0 2
15 0 3 0 3 3 0 2 0 0 1
16 0 3 1 0 2 0 3 3 0 0
17 0 3 0 0 1 0 3 0 0 0
18 0 1 3 3 2 0 3 0 0 0
19 0 1 1 3 3 0 0 0 0 0
20 0 3 1 0 2 0 3 0 0 0
21 0 2 0 0 3 1 3 0 2 0
22 0 1 2 3 2 3 3 0 3 0
23 0 3 1 0 3 0 2 3 0 0
24 2 3 0 3 3 0 2 0 3 0
25 1 2 0 0 1 0 3 0 3 0
26 0 3 3 2 3 0 2 0 0 0
27 0 0 0 3 1 3 3 0 3 0
28 0 1 1 3 2 1 3 0 3 0
29 3 0 0 3 3 0 2 0 2 3
30 3 1 0 3 3 0 2 0 2 3
2:rare;3: frequent;4: abundant;5:extremelyabundant.Abundance classrankingwasbased onthefield
excursionwith the largestnumberofindividuals recorded.
Since the assessment approachemphasisesbreeding species with self-sustainingpopulations,the
determinationofautochthonyisessential.Exuviaewerethemostimportantindicatorsofresidentpopulations.
For collecting exuviae the riparianvegetation,emergingparts ofwaterplants,dead wood and abiotic
riparianstructuressuchassteepbanksandgravelsubstrateweresurveyedthoroughlyateachfieldsampling
datefollowingthetimeschedule ofSCHMIDT(1985).Identification ofexuviae wasmadeaccordingto
HEIDEMANN & SEIDENBUSCH (1993). In addition to exuviae, newly hatchedimagines,larvae,
reproductivebehaviour (copula, tandem, egg deposition),territorialbehaviour, imaginesinabundance
class 3,4or5,imaginesobservedoveraperiod> 1 month and therecord ofagivenspeciesatseveral
OdonataHabitatIndex(OHI) 359
waterbodieswithinthe studyareawereusedasindicatorsforautochthony.
Theparametersnecessaryforthecalculation oftheOdonateHabitatIndex(OHI)isthespeciesinventory,
the species-specific habitatvalue,theindication weightandthe abundance foreach species.Inorder to
describe the habitat preferencesnumerically,a10-pointsystem wasused.Accordingtospecific habitat
preferences,10valencypointsweredistributedamongfivehabitattypes.Forexample,aspeciesexclusively
inhabitatingtemporary poolsis given10valencypointsintherelevantcategory (H5: 10);foreurytopic
speciesoccurringinawiderangeofstagnantwatersofafloodplainsystem,the 10pointsavailable willbe
more orlessevenly distributedbetween differentcategories(HI; 2,H2:2, H3:2, H4:2,H5:2). This
valencypointdistributionprocedurehasbeen developedonthe basis ofthe authors’ recordings in the
investigationareaaswell asatother sites,onautecologicaldata and onexpert consulting. Indication
weights ranging from 1 for eurytopicspecies to 5 for stenotopicspecies (calculationaccordingto
SLADECEK (1964))havebeen allocated toeachspeciesin ordertoidentifysensitivespecies(indication
weight>3).
Theassessment isbased ontheabundance ofa setofdragonflyspeciesappearinginriver/floodplain
systemswithinspecifichabitattypes.Thesehabitattypes (H1-H5)followagradientoflateralconnectivity
with the mainriver channel,rangingfrom HI (Eu-/Parapotamon)toisolated floodplainwaters (H5;
Palaeopotamon).The definition ofthese types isinlinewithhabitattemplatesdescribedfor dragonfly
associations(JACOB, 1969;WARINGER, 1989;CHWALA &WARINGER, 1996)and withbackwater
classifications (WARINGER-LOSCHENKOHL &WARINGER, 1990;WARD&STANFORD, 1995):
HI: Eupotamalpermanent water bodies;themain riverchannelandits littoral areas andassociated
inshore structures;permanentlyconnectedsidechannelswithhighhydrologicalconnectivityreflecting
waterlevelfluctuationsofthemainchannel;nosedimentationprocesses; +/-loticbackwatersections
downstream artificialopeningsofweirs;nomacrophytecommunitiesintheopenwater,openbanks
orPhalaridetum stands in thelittoral area,ripariantrees andshrubs;sandandgravelsubstratesare
dominating.
H2: Littoral areas ofparapotamal(e.g. deadarmsretainingaconnectiontothe main channel)or
plesiopotamal(e.g. former braided segments thatbecame disconnected fromthe main channel)
standingand permanent backwaters; littoral areasoflargegravel pits in the floodplainarea;
(significantly)reducedhydrologicalconnectivityanddynamics;openbanks;only fewmacrophytes
(e.g.Phalaridetum);ripariantrees andshrubs; highproportionofsandandgravelsubstrates.
H3: Openwaterareasofplesio-andpalaeopotamalpermanent standingwatersandgravelpits,typically
withfloatingmacrophytes;significantlyreduced hydrologicalconnectivityanddynamics;highdegree
ofsedimentation;dominatingmacrophyteassociations: Myriophyllo-Nupharetum.
H4; Littoral areasofplesio- andpalaeopotamalpermanent standingwaters and gravelpits withreed
belts;significantly reducedhydrologicalconnectivityanddynamics; sedimentationhigh;dominating
macrophyteassociations: Phragmiletum,Typhetum, Sagittario-Sparganietum;sludgy sediments
dominate.
H5: Temporarypools;hydrologicalconnectivityanddynamicssignificantlyreduced;sedimentationhigh;
atleastonedried-upperiodperyear(mostlysummer-autumn); dominatingmacrophyteassociations;
Phragmiletum,Typhetum,Sagittario-Sparganietum,Magnocaricetum;terrestrial vegetation.
As thisclassification referstopotentialdragonflyhabitatsandnottowholewaterbodies,severaltypes
may occuratonewater body:e.g.littoral and openwater areas ofadisconnected backwater may be
classified asH2, H3,andH4.
Individual species-specific habitatvalues (HV)arecalculatedby thefollowingequation:
(1 xHI +2xH2 +3xH3 +4xH4 +5xH5)
HV=
10
withHV-valuesrangingfrom 1to5(rheotopicspecies:HV= 1;speciespreferringtemporarywaters: HV=5).
360 H.Schultz,LA.Waringer&A.Chovanec
TableII
Dragonflyspeciessofarreportedfromfloodplainwaterbodies ofthe Austrian Danube,showinghabitat
valencies, habitatvalues(HV) andindication weights(IW).H1-H5refers tohabitattypes definedinthe
methodssection
SSppeecciieess HHII HH22 HH33 HH44 HH55 HHVV IIWW
CCAALLOOPPTTEERRYYGGIIDDAAEE
CCaalloopptteerryyxxsspplleennddeennss((HHaarrrriiss)) 99 11 11,,11 55
CCaalloopptteerryyxxvviirrggoo((LLiinnnnaaeeuuss)) 1100 11,,00 55
LLEESSTTIIDDAAEE
LLeesstteess bbaarrbbaarnutss((FFaabbrriicciiuuss)) 22 88 44,.88 44
LLeesstteessddrryyaassKKiirrbbyy 22 88 44,,88 44
LLeesstteessssppoonnssaa((HHaannsseemmaannnn)) 11 11 44 44 33,,99 11
LLeesstteessvviirreennssCChhaarrppeennttiieerr 44 66 44,,66 33
LLeesstteess ((CChhaallccoolleesstteess))vviirriiddiiss((VVaannddeerrLLiinnddeenn)) 11 22 33 44 33,,77 11
SSyymmppeeccmmaaffuussccaa((VVaannddeerrLLiinnddeenn)) 11 11 22 55 11 33,,44 11
PPLLAATTYYCCNNEEMMIIDDIIDDAAEE
PPllaattyyccnneemmiissppeennnniippeess((PPaallllaass)) 44 33 22 11 22,,00 11
CCOOEENNAAGGRRIIOONNIIDDAAEE
CCooeennaaggrriioonnhhaassttuullaattuumm((CChhaarrppeennttiieerr)) 22 66 22 44,.00 33
CCooeennaaggrriioonnppuueellllaa((LLiinnnnaaeeuuss)) 11 22 22 44 11 33,,22 11
CCooeennaaggrriioonnppuullcchheelllluumm((VVaannddeerrLLiinnddeenn)) 11 22 77 33,,55 33
CCooeennaaggrriioonnsscciittuulluumm((RRaammbbuurr)) 66 44 33,,44 33
CCeerrcciioonn Ulinnddeennti((SSeellyyss)) 11 66 33 33,,11 33
EEnnaallllaaggmmaaccyyaatthhiiggeerruumm((CChhaarrppeennttiieerr)) 22 11 55 22 22,,77 11
EErryytthhrroommmmaannaajjaass((HHaannsseemmaannnn)) 11 88 11 22,,99 44
EErryytthhrroommmmaavviirriidduulluumm((CChhaarrppeennttiieerr)) 11 88 11 22,,99 44
IIsscchhnnuurraa eelleeggaannss((VVaannddeerrLLiinnddeenn)) 11 33 22 33 11 33,,00 11
IIsscchhnnuurraappuummiilliioo((CChhaarrppeennttiieerr)) 11 22 77 44,,55 33
CCeerriiaaggrriioonntteenneelllluumm ((DDeeVViilllleerrss)) I1 11 77 11 33,,88 22
PPyyrrrrhhoossoommaannyymmpphhuullaa((SSuullzzeerr)) 22 22 66 33,,22 33
AAEESSHHNNIIDDAAEE
AAeesshhnnaaaaffffiinniissVVaannddeerrLLiinnddeenn 99 11 44,,11 55
AAeesshhnnaa ccyyaanneeaa((MMuueelllleerr)) 1122 33 44 33,,00 11
AAeesshhnnaaggrraannddiiss((LLiinnnnaaeeuuss)) 11 66 33 33,,22 33
AAeesshhnnaaiissoosscceelleess((MMuueelllleerr)) 33 77 33,,77 44
AAeesshhnnaajjuunncceeaa((LLininnnaaeeuuss)) 33 77 33,,77 44
AAeesshhnnaammiixxttaaLLaattrreeiillllee 11 33 66 33,,55 33
AAeesshhnnaavviirriiddiissEEvveerrssmmaannnn 66 44 33,,44 33
AAnnaaxxiimmppeerraatloorrLLeeaacchh 1111 55 33 33,,00 11
AAnnaaxxppaarrtthheennooppeeSSeellyyss 55 55 33,,55 33
BBrraacchhyyttrroonnpprraatteennsseeMMuueelllleerr 11 11 88 33,,66 44
HHeemmiiaannaaxxeepphhiippppiiggeerr((BBuurrmmeeiisstteerr)) 55 55 33,,55 33
OdonataHabitatIndex(OHI) 361
Tablen,continued
SSppeecciieess HHII HH22 HH33 HH44 HH55 HHVV IIWW
GGOOMMPPHHIIDDAAEE
GGoommpphhuussffllaavviippeess((CChhaarippeennttiieerr)) 1100 11,,00 55
GGoommpphhuussvvuullggaattiissssiimmuuss((LLiinnnnaaeeuuss)) 77 33 11,,33 44
OOnnyycchhooggoommpphhuussffoorrcciippaatluuss((LLiinnnnaaeeuuss)) 99 11 11.,11 55
OOpphhiiooggoommpphhuusscceecciilliiaa ((FFoouurrccrrooyy)) 1100 11,,00 55
CCOORRDDUULLEEGGAASSTTRRIIDDAAEE
CCoorrdduulleeggaasstteerrbboollttoonnii((DDoonnoovvaann)) 1100 11,,00 55
CCOORRDDUULLIIIIDDAAEE
CCoorrdduulliaiaaaeenneeaa((LLiinnnnaaeeuuss)) 55 22 33 22,,88 22
EEppiitthheeccaabbiimmaaccuullaattaa ((CChhaarrppeennttiieerr)) 22 66 22 33,,00 33
SSoommaattoocchhlloorraaßflaavvoommaaccuullaatlaa((VVaannddeerrLLiinnddeenn)) 11 22 77 33,,66 33
SSoommaattoocchhlloorraammeerriiddiioonnaalliiss NNiieellsseenn 99 11 l1.l,155
SSoommaattoocchhlloorraammeettaalllliiccaa((VVaannddeerrLLiinnddeenn)) 55 22 33 22,,88 22
LLEEBBEELLLLUULLIIDDAAEE
CCrrooccootthheemmiiss eerryytthhrraaeeaa((BBrruulllldé)) 55 33 22 22,,77 22
LLeeuuccoorrrrhhiinniiaa ppeeccttoorraalliiss((CChhaarrppeennttiieerr)) 88 22 44,,22 44
LLiibbeelllluullaa ddeepprreessssaaLLiinnnnaaeeuuss 44 22 11 33 33,,33 11
LLiibbeelllululalaffiuillvvaaMMuueelllleerr 66 22 22 11,,88 33
LLiibbeelllululalaqquuaaddrriimmaaccuullaattaaLLiinnnnaaeeuuss 11 22 77 33,,66 33
OOrrtthheettrruummaallbbiissttyylluumm((SSeellyyss)) 11 77 11 11 22,,22 22
OOrrtthheettrruummbbrruunnnneeuumm ((FFoonnssccoolloommbbee)) 77 33 11,,33 44
OOrrtthheettrruummccooeerruulleesscceennss ((FFaabbrriicciiuuss)) 66 11 22 11 22,,22 22
OOrrtthheettrruummccaanncceellllaattuumm ((LLiinnnnaaeeuuss)) 11 77 11 11 22,,22 22
SSyymmppeettrruummddaannaaee ((SSuullzzeerr)) 44 66 44,.66 33
SSyymmppeettrruummddeepprreessssiiuussccuulluumm((SSeellyyss)) 77 33 44,,33 44
SSyymmppeettrruummffllaavveeoolluumm((LLiinnnnaaeeuuss)) 33 77 44,,77 44
SSyymmppeettrruummffoonnssccoolloommbbeeii((SSeellyyss)) 66 22 22 33,,00 33
SSyymmppeettrruummmmeérriiddiioonnaallee ((SSeellyyss)) 55 55 44,,55 33
SSyymmppeettrruummppeeddeemmoonnttaannuumm((MMuueelllleerr)) 11 22 66 11 33,,44 22
SSyymmppeettrruummssaanngguuiinneeuumm((MMuueelllleerr)) 22 55 33 33,,99 22
SSyymmppeettrruummssttrriioollaattuumm((CChhaarrppeennttiieerr)) 44 11 33 22 33,,33 11
SSyymmppeettrruummvvuullggaattuumm((LLiinnnnaaeeuuss)) 22 11 55 22 33,,77 11
TheOdonateHabitat Indexisbasedonthesummation ofthehabitat values,abundances andindication
weightsofall speciespresentatthesamplingsite andiscalculated usingthefollowingequation:
2 (HV xAxIW)
OHI=
1(AxIW)
whereHV isthehabitat value,Aisthe estimated abundance (classes 1-5)andIWisthespecies-specific
indicationweight.Thisresultsinanumberbetween 1and5,indicatinghabitatpreferencesofthedragonfly
communitybreeding attheinvestigationsite. CHOVANEC & WARINGER (2001)have compileda
362 H.Schultz, J.A.Waringer&A.Chovanec
referencespecieslistfortheAustrianDanubebasedontheresultsofrecentinvestigations,andtheecological
requirementsofpotentialspeciescharacteristicoffloodplainsystems(Tab.II).Thisinventorycorresponds
toalargeextenttothe speciesinventoryobtainedfromhistorical data(BRAUER, 1851,1856;BRAUER
&LOW, 1857; VORNATSCHER, 1938).Therefore,this species list consistingof60 speciesfrom9
familiescanbe used astargetorreference list forthisarea. 60% ofthesespeciescanbe classified as
sensitivespecies.
Bycomparingthe statusquoofariver/floodplainsystem with referenceconditions, deviations caused
bydisturbancesbecomevisibleandhave tobeclassified intofiveclasses.Mostimportantly,thedefinition
ofreference criteria - suchasabiotic habitatcriteriaandpotentiallyoccurring species- musttake into
accountthe specificcharacteristics ofeachriver type.This iswhyonly generalcriteriaforthisdragonfly-
-based approacharegiven,leavingroomforadaptationstospecificconditions (Tab.III).
RESULTS
SPECIES COLLECTED
Duringthe investigation period, atotal of 11 Zygoptera and20 Anisoptera species
was recorded(Tab. IV);thisnumberis equivalent to51.7%ofthespecies inventory so
far reportedfromDanubianfloodplains inAustria(Tab.II)andto40.3%oftheAustrian
Odonata species. Withtheexception ofPyrrhosoma nymphula and Ophiogomphus
cecilia, the autochthony ofthe remaining species couldbe confirmedby recordsof
larvaeorexuviaeand/orby thecriteriasummarizedinthemethodssection.Inaddition,
fifteenspecies belongtothegroupofsensitive(stenotopic)species (indicationweights
>3) with Calopteryx splendens (maximum abundance class = 5) and Gomphus
vulgatissimus(maximumabundanceclass=4) beingtheonly trulyrheophilic species.
Abundantand/orwidespread odonatesinthe study area were Calopteryx splendens,
Platycnemis pennipes, Lestes viridis, Coenagrion puella, Enallagma cyathigerum,
IschnuraelegansandSympetrumsanguineum. Red-listspecies classifiedas“regionally
extinct”, “critically endangered” or “endangered” in Lower Austria (RAAB &
CHWALA, 1997)includeCoenagrion pulchellum (maximum abundanceclass atthe
study area=3), Aeshnaisosceles (2), Anaxparthenope (2), Brachytronpratense(3)
andLeucorrhiniapectoralis(maximumabundanceclass=4)(Tab.IV).
DIVERSITY
Odonataspecies diversitywashighestatsites22,2, 4,5,9,14and 10whereupto 18
species (including up to6 sensitive species) wererecorded (Tab. IV). Thismay be
explained bythefactthathabitatrequirements forthreeofthefourOdonataassociations
valid forthe Danubianfloodplains in Austria (= thelimnophilic Erythromma-Anax
imperator-, Lestes-Sympetrum- and Orthetrum-Libelluladepressa-coenosis;
WARINGER, 1989) wereclearly metby thesesites. Suchrequirements encompass
thecombinationofreedbelts,openwaterzones,sub-andemergedaquatic macrophytes
(including floating leaves) andunobstructed,openriparian zones; inaddition,a high
degreeofinsolationmust alsobe given. At sites whereoneor theotherofthese five
OdonataHabitat Index (OHI) 363
basicrequirements was lacking,species diversity wassignificantlylower.Forexample,
at site 15, reed belts and unobstructedbank sections were present, but aquatic
macrophyteswithfloatingleaveswerelackingandinsolationwasobstructedbyriparian
trees, resulting ina decreaseofdiversity downto9species (oneof themasensitive
species). InTableIV canbe seen thatatsite 15 membersof the Erythromma-Anax
imperator-coenosis (e.g. Erythromma najas, E. viridulum, Anax imperator, A.
parthenope, Aeshnagrandis) wereclearlyadversely affectedby therestricted habitat
requirements listedabove.Diversity was lowestatsites 11, 24and 19(3-4 species, 1
TableIII
Classification schemeforthe dragonfly-basedassessment ofriver/floodplainsystems(CHOVANEC&
WARINGER,2001)
Criteria Ecologicalstatus
I/high II/good III/moderate IV/poor V/bad
General Dragonfly Dragonfly Dragonfly Onlyremnantsof Fewifanyspecies
description community community community thetype-specific arepresent that
(nearly)totally slightlydeviates significantly dragonfly correspondtothe
correspondstothe fromthetype- deviatesfromthe community; type-specific
type-specific specificreference type-specific ecologicalintegrity reference
reference condition; reference heavily disturbed community;
condition; ecological condition; ecologicalintegrity
ecologicalintegrity integrity ecologicalintegrity completely
(nearly) slightlydisturbed significantly disrupted
undisturbed disturbed
Autochthonous Speciesofallor Speciesofallor Few orsome Feworsome Somefamiliesare
species nearly allfamilies nearly allfamilies familiesare familiesare missing;mostof
ofthereference occur;numberof missing; missing; theexpected
communityoccur; speciesisslightly someormany many expected species aremissing
totalnumberof reduced expectedspecies species aremissing
speciesishigh aremissing
OHI OHIrangehigh OHIrangehigh OHIsindicatethat OHIsindicatethat OHIsindicatethat
(>1.5);allhabitat (> 1.5);4or5 1ormorehabitat morethan 1habitat morethan 1 habitat
types+/-equally habitattypesare typesaremissing. typesaremissing. types aremissing,
represented orH1 present,atleastHI rangeofOHIs range ofOHIs rangeofOHIs
dominating; hastobefound, < 1.5 <1.5 < 1.5
meanOHI butis not
dominating;
meanOHI<3.5
Sensitive Speciesnumber Numberof Numberof Only fewsensitive Nosensitive
autochthonous high,proportion sensitivespecies sensitivespecies species species
species ofsensitive highorslightly slightlyor
species corresponds; reduced significantly
tothatinthe reduced
referencecommunity
orisslightlyreduced
364 H.Schultz, J.A.Waringer&A.Chovanec
(s).
1166 4 3 3 33 22
species 454 443
1155 33 22 5 3533 4 22 22
sensitive
1144 33 4 4 22 2 22 22 22 22 22 22
22
and/or 1133 5 22 22 22 2
(a)
1122 5 33 11 22
autochthonous abundant)
1111 44 33 4
extremely 1100 33 4 4 44 44 4 2 22
as 34 34 22
status 544455533445
99 22 3 3 33 33 3 2 22 22 33
5: ssiittee
their
abundant,
SSaammpplliinngg88 3 33 22 11 3
showing
4: 77 3 5 22 22 3 22 11 22 22
Austria, frequent,
23213
66 434343 5 3 1
IV
Lower 3: 4433533
Table rare, 55 3 5 4 22 33 5 22 2 22 22 22 22
22
Tulin, 2: 434
44 4 33 4 3 11 3 22 2 22 22 11 2
single,
at
Danube (1: 33 3 22 4 3 3 22
classes
the 22 4 4 22 44 4 2 22 22 22 11 22
of 22
abundancy
waterbodies i1 55 5 4 2 2 22
ss ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++
indicate
floodplain
aa ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ ++ f+ ++ ++ ++ ++ ++ ++
1-5
at
collected
sspplleennddeennss ppeennnniippeess ppuullcchheelllluumm ccyyaatthhiiggeerruumm vviirriidduulluumm nnyymmpphhuullaa pprraatteennssee vvuullggaattiissssiimmuusscceecciilliiaa mmeettaalllliiccaa
species ZZyyggoopptteerraa ssppoonnssaavviirriiddiiss ppuueellllaa nnaajjaass eelleeggaannss AAnniissoopptteerraaaaffffiinniiss ccyyaanneeaa ggrraannddiissiissoosscceelleess mmiixxttaa iImmppeerraattoorrppaarrtthheennooppee OOpphhiiooggoommpphhuuss aaeenneeaa
Dragonfly SSppeecciieess CCaalloopptteerryyxxLLeesstteess LLeesstteess PPllaattyyccnneemmiiss CCooeennaaggrriioonnCCooeenmaggrrioionnEEnnaallllaaggmmaaEErryytthhrroommmmaaEErryytthhrroommmmaa IIsscchhnnuurraa PPyyrrrrhhoossoommaa AAeesshhnnaa AAeesshhnnaa AAeesshhnnaa AAeesshhnnaa AAeesshhnnaa AAnnaaxx AAnnaaxx BBrraacchhyyttrroonn GGoommpphhuuss CCoorrdduulliiaa SSoommaattoocchhlloorraa