Hydro-ecological relations in the Delta Waters
Hydro-ecological relations in the Delta Waters Hydro-ecological relations in the Delta Waters
A CMANGING DEtTdl; EFFECTS OF L&E COASTAL ENGINF5RING WOW ON FEEDB'G ECOLOGICAL RELATIONSKIPS A5 ILLUSTRATED BY WAlXlWIBDS P.M. Meire, 3. Seys. T. YsebaerC. P.L. Mekinger and H,~.hl. Baptist In the Delta area of the South-Wwt Netherlands the majrrrity of estuarine eaoagstems has disappeared due to large coastal engiaeeriag works, creating new artificial saline Emd Freshwater lakes. Thege hydrodynamical changes had enormous consequences for plants and animals. In this paper the changes in the avifauita are desccikd. The Poordelta is charrtcterized by a La~ge number of diving ducks and gulls. In comparison with the tidal basins, where the benthivormus species (mainly waders) dominate, numbers of h~rbiubres and piscivoTes increased snbstantially in the new lakes, while waders near17 dtaappeared. Herbivores dominate the avLfaona of the lakea. This differentiation is even more obvious in the distribution of individual species, since same species prefer fresh over saline conditions and vice versa, In order to understand the observed distribution patterns, the densities of different bird grows were compared with estimates of the available food. In the tidal azeas and the saline lakes a clear relation beween piscivore bird density and D~biid density (their main grey species) was cbserved. BLeo wader densities in the Cidal basins *ere clearly related to their food supply. Densities of herbivores are comparable between various basies. Thetr food saurce is very variable and hence impossible to estimate. The distribution a£ div*g ducks. feeding a$Iy on macrobenthos. is vety puzzling and .seems not at all related to food supply. This indicates factcrs other thaa food supply
are determining the dfstrlbution af birds in che Delta r2s well. NeM to ecolo@cal factors mch es ppulatiob. size, arlgracian partem and diet selecriob. human arrivities affect bir&i, often negatimely, in a varietg of nays. Disttubailce, poLlution artd habitat loss are Lnnoediate threats. Several tomagament options are available and discussed in Drder Ca inpmve the acologlcal cwditions. Gver Ehe l46t tws deeaaes the wealled Delta ,a- ?n fhe asu~hwsrern part of the Netherlands has changed profgunLUy. 14 this area $he rivers ~Wn. W and Sehdde £lea ineo B& sea thrangh e cosplelt s.p%em of estuaries.. Is respanwe to the disastms etcrro £l@od of 1953, in whim .aaSut l:&O.O people were killed, as BBlbfti~als plan @>E aalm@ up all ~ht me e$tcr&i~e$ was deedoped. In 1-967 the &.xec&ion of this plan, &Ithod& @rptte8 id the b&Se Df tHe yeais, s s mleted. ThLs ~ ~ u h tn e d ~profalrnd chaages kn thil eelbgieal relatims, as lilrge 't:idal .&reds di&p$ear@d and ~ e habitatir, w such as stagnant saline wd bi&.kish lekes, were cr-ed. 5ie.c~ d$.scxibieg all these eeolsggtcal chrtng*~ is fmpossible. In $his paper W@ shall reetrict eu~selves to descLlibe tibw tha oeeu.s.r?nce and d~i.@%ribation o* birds wer zhe aiffereat basin9 Changed and xe isdieate reia%imxv with food suppigi and otber faceors.. W.@@, the area is? very imparranr for btsds apt is^, et al, 198&; Saeijs a~d Baptigt, 1~91771 d., as the gentgal pwblle is sepsAtive tg birds, the7 haye p.byzld a relatfvely ~ortanc role in deci.s:i@ndiug (ens. in eke disewasian sht at spen or closed b,mte~sBhel@e: d~riqg the Uo6sre-s #f the Philips- and OeatettBni; in tbe eurrent dbcusriori abwt rhe &its to be @et or reeteatilbn in Oasfemchelde erc.l. Xn the fiei.wt part of thfs papixr ttie Wbitati in the De'lyta area and the ohsewed chaQgesia tht?. occnrt-ence ef waferbird% are descritred. In the: saEBnil p& some fwtoes inflmencing tiiis obse.md distTibutan. bein$ Toad BUatLability and ~nat?Xp btber fac&ors as migration pattwns. pdpwlatton bize and thlaran fiite&ereuce are Wyxed.
- Page 66 and 67: period 1980-19$3 in an increase of
- Page 68 and 69: model calculations reveal that a ni
- Page 70 and 71: Table 3 PreUmInary carbon budget of
- Page 72 and 73: Water life of Lake Grevelingen
- Page 74 and 75: macrophytes livkg on or rooting in
- Page 76 and 77: less predictable for water managers
- Page 78 and 79: ILWNEWIJK, A.. KEIP, C., 1988. De v
- Page 80 and 81: XBE CHANGING TmAL LAMXiCAPE I N TEE
- Page 82 and 83: The storm surke of L&Z1 A.D., knorm
- Page 84 and 85: osi* rn@8IOIP m .SL 4 Has F~~ULB 3
- Page 86 and 87: During the 19th century man starts
- Page 88 and 89: mudflats have retreated some 100-20
- Page 90 and 91: aq811~33a.e~ pue 3pTatlJS uxaJsafi
- Page 92 and 93: Erosion by waves of sandy shoals (c
- Page 94 and 95: Lt has been estimated that the sedi
- Page 96 and 97: Implementafion of the Delta Project
- Page 98 and 99: ECOLOGICAL DEVELOWdENT OF SALT MAKS
- Page 100 and 101: fn tidal water systems sedimentatio
- Page 102 and 103: hierarchical position. Tn the egtua
- Page 104 and 105: Of course. tke environmental change
- Page 106 and 107: wind erasson, desaliuation, aeratio
- Page 108 and 109: Fonner tirtal flats with saltmarsh
- Page 110 and 111: Grevelingen. Lake Veere and Krammer
- Page 112 and 113: As mentioned above aa important que
- Page 114 and 115: A seaond important perspective for
- Page 116: BEEEXNX, W.D. and 80ZBf&. J. L9M. T
- Page 121 and 122: this volume or in Duutsaa, et aL, 1
- Page 123 and 124: artificial waterflow was created af
- Page 125 and 126: of waterbirds occur regulsrly. The
- Page 127 and 128: . DISTRIBUXIOBI OF WATEJBIRoS OVER
- Page 129 and 130: small bird$ extludiag them vill net
- Page 131 and 132: In order to lsok for relatiouehips
- Page 133 and 134: Table 3 Biomass of macroroobenthos
- Page 135 and 136: freshwater basins. Clearly the pres
- Page 137 and 138: scmthem bottueary o-f the winter di
- Page 139 and 140: OCLURRENCE AND DIET QF B ~T .tUQ 80
- Page 141 and 142: 5.2 H- factors Next to all fartors
- Page 143 and 144: Bewick's Swans (Cygnus columbariusl
- Page 145 and 146: m's activiries do not always have t
- Page 147 and 148: measure affecting food supply or av
- Page 149 and 150: DOQiWT$QS, G. 4 TWISK, F., 1987. De
- Page 151 and 152: MEININGEB, P.L. and HAPEREX, A.M.M.
- Page 153 and 154: PISCIVORES Litfle Grebe Great Crest
- Page 156 and 157: IPYBRO-EGOLOOIOAL BELATIONB ZN THE
- Page 158 and 159: apart from upstream purification; -
- Page 160 and 161: Storm surge barrier Eastern Scheldt
- Page 162 and 163: - In addition to existing managemen
- Page 164 and 165: Nature is pliable. Belattvely young
- Page 166 and 167: Ro. 1. No. 2. SQ. 3. Investigations
A CMANGING DEtTdl; EFFECTS OF L&E<br />
COASTAL ENGINF5RING WOW ON FEEDB'G<br />
ECOLOGICAL RELATIONSKIPS A5 ILLUSTRATED BY WAlXlWIBDS<br />
P.M.<br />
Meire, 3. Seys. T. YsebaerC. P.L. Mek<strong>in</strong>ger and H,~.hl. Baptist<br />
In <strong>the</strong> <strong>Delta</strong> area of <strong>the</strong> South-Wwt Ne<strong>the</strong>rlands <strong>the</strong> majrrrity of estuar<strong>in</strong>e<br />
eaoagstems has disappeared due to large coastal engiaeeriag works,<br />
creat<strong>in</strong>g new artificial sal<strong>in</strong>e Emd Freshwater lakes. Thege<br />
hydrodynamical changes had enormous consequences for plants and<br />
animals. In this paper <strong>the</strong> changes <strong>in</strong> <strong>the</strong> avifauita are desccikd.<br />
The Poordelta is charrtcterized by a La~ge number of div<strong>in</strong>g ducks and<br />
gulls. In comparison with <strong>the</strong> tidal bas<strong>in</strong>s, where <strong>the</strong> benthivormus<br />
species (ma<strong>in</strong>ly waders) dom<strong>in</strong>ate, numbers of h~rbiubres and piscivoTes<br />
<strong>in</strong>creased snbstantially <strong>in</strong> <strong>the</strong> new lakes, while waders near17<br />
dtaappeared. Herbivores dom<strong>in</strong>ate <strong>the</strong> avLfaona of <strong>the</strong> lakea. This<br />
differentiation is even more obvious <strong>in</strong> <strong>the</strong> distribution of <strong>in</strong>dividual<br />
species, s<strong>in</strong>ce same species prefer fresh over sal<strong>in</strong>e conditions and<br />
vice versa, In order to understand <strong>the</strong> observed distribution patterns,<br />
<strong>the</strong> densities of different bird grows were compared with estimates of<br />
<strong>the</strong> available food. In <strong>the</strong> tidal azeas and <strong>the</strong> sal<strong>in</strong>e lakes a clear<br />
relation beween piscivore bird density and D~biid density (<strong>the</strong>ir ma<strong>in</strong><br />
grey species) was cbserved. BLeo wader densities <strong>in</strong> <strong>the</strong> Cidal bas<strong>in</strong>s<br />
*ere clearly related to <strong>the</strong>ir food supply. Densities of herbivores are<br />
comparable between various basies. Thetr food saurce is very variable<br />
and hence impossible to estimate. The distribution a£ div*g<br />
ducks.<br />
feed<strong>in</strong>g a$Iy on macrobenthos. is vety puzzl<strong>in</strong>g and .seems not at all<br />
related to food supply. This <strong>in</strong>dicates factcrs o<strong>the</strong>r thaa food supply
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