Hydro-ecological relations in the Delta Waters

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Overall population size Fs very irpporCane as well. Indeed in the last decades a few species, lac the Greylag Gowe (Pig. 8) and the Coxmurant, Wreased in numbers in the Delta area. phis is not due fa any ehanges in the fbbd suepl~ hut to an overall increase in the population. In Europe the Greylag population ha* increased from 30 DUO to 1% 000 bemen 1974 and 1984 (Madaen, 1987). The total population size of arctic breeding wecies eau vary substantially between years due to the varying breeding success. Of ether spactes (e.g. DuW) pspulatiwn siae decreased dwriqg the last years, a declfae which is obvious in the couunte from the Delca area. Tlvese were all Eacrors ac~tiqg on a lazge sea&. M the DeLlt area itself, several z~pccts rYf prey reLettfon may fafluence the diatribwtion af a species. In she asalf,t~s prasent-a ad1 prey 8pedea were lrrmped ed4?aca large categeiesi Same species are, hCmemr, uee specXaLiz&. IeeakrD, vh@reas Others feed a* a large vazlaty of p?* species. Tlris may affect the occurreace ti£ birds qutte subgtantliaf.ly. In the Veerse Neex Dlva sp. fo- a v.&y important prep item far hehivor~e Such ns eonss aud Br*nt Geese.. nse to predarlqu and *be natural mortality of the plant* the aviril&le amount ,of Qlve q. declines rapidly *u.tumn vwdnter. bnring that the BanL Geese switch eo *Chef pray available in ehe area. d d y pastures .W$ asaMe land, a& their nmbers replain stable wnrii April-Hay (Fig. 91. Owte, kqwevez, do net change diet and amhers start te decline aireaey in Jmwarp, mch earlier tkaa in other part6 of the De~lta. Even for birtl4 Se4ddfs$ aa me prey fssp.eei&s, t&ce mi@t be facmts compli~wzing the relative prey abondande m hird dasiff. The i2ystet"aatehn is the most nwraus %del ,gp.eel&s in €he Wd*refm&el~& and ie a.lmst edcrusivelg faeds m 'Cockle* and Mussels,, %irB back Inbtvlda2 cinly feeczing on One of tW&L? %~&Les. %-he selertiw of mnssels ha8 W& s~turliQd in detail lHerr& w d ErySnck. 1986.3 Mere, 1B871 sad it is ~mtnd thde there is n6t mily selectiim foi laper miwels but even Eo? the chin%er-shelled i@ivfd+ls wishin a lengch cLies,. It has h~en shoran that these selection patterns are etuced by energeti'f constraints. Wile the pp6t .~pening-.&l eureseL6 %a wt rewartB.ng due to very -U ylela of fl,osh, tha thick sirelied mussele
OCLURRENCE AND DIET QF B ~T .tUQ 80 - a 2 40'- U (D 8 -20 SBP w'r N~SY 6x0 J& F.XS APE ,,g. I,. 1 m 0 066URANCti AND LEET DF IFT 108. -- - l00 W U L W - 60 G, 9, DI 2 D 2QL 0 b Q SBP QdT NOW S2SW JW FFsB AQE >, -ZQ @ are too hard to open. Tbis selection pattern implies that only a part of the prey population is really available to the birds, caused by the selectitin-behaviour of the birds themselves. Eowever, prey availabilicg is often influenced by the prey itself. In intertidal areas many maerobenthic spec%es may be buried deep in the substrate, well beyond
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Netherlands organkation fw applied
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TNO Commlitee on Hydrological Resea
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2 RIVER WATER AM) THE QPALITH OF TB
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B.J.M. Baptist BIJkswaterstaat. Tid
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This approach will put to use what
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Estuaries that have not been influe
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2 CHIWGES XN TEE DELTA The Delta ar
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area decltned cnnside~ably, leadins
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Plan, then it is apparent tbt the s
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Tiddl flats df the Eastem Seheldt v
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tracefore possible to convert the a
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Figsrlre 7 Changes in the cadrnrum
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prevention measures are desirable h
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elationships between different spec
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Bio-essay Weriments with polluted s
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considerable thought to drawing up
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ShLOUONS, W. and BYSINK, W.D., 1981
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are taken. The first year after the
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The Hollands DiepJnaringpllet is pa
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In 1976 the determination of chlozo
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, 0.66 m 0,s - 0.02 1989 I 0.86 - 0
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Table 3 Eutrophication of the Volke
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Laks Volkarek ---- Lake Zoom 0.40 0
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4 WAGBEET MEdSIIRaS TO PEEVBT OR LT
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Table 5 gives estimtes of the phosp
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In principle, two states of equilib
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Zooplankton (Alma affinis) Pike (Es
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EUTROPHICATION OF ESTUAAIES AND BRA
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The average discharge of Xhine and
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and only l-2% cows frm the aive Sch
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highest trophic potential: nutrient
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period 1980-19$3 in an increase of
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model calculations reveal that a ni
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Table 3 PreUmInary carbon budget of
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Water life of Lake Grevelingen
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macrophytes livkg on or rooting in
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less predictable for water managers
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ILWNEWIJK, A.. KEIP, C., 1988. De v
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XBE CHANGING TmAL LAMXiCAPE I N TEE
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The storm surke of L&Z1 A.D., knorm
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osi* rn@8IOIP m .SL 4 Has F~~ULB 3
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During the 19th century man starts
Page 88 and 89: mudflats have retreated some 100-20
Page 90 and 91: aq811~33a.e~ pue 3pTatlJS uxaJsafi
Page 92 and 93: Erosion by waves of sandy shoals (c
Page 94 and 95: Lt has been estimated that the sedi
Page 96 and 97: Implementafion of the Delta Project
Page 98 and 99: ECOLOGICAL DEVELOWdENT OF SALT MAKS
Page 100 and 101: fn tidal water systems sedimentatio
Page 102 and 103: hierarchical position. Tn the egtua
Page 104 and 105: Of course. tke environmental change
Page 106 and 107: wind erasson, desaliuation, aeratio
Page 108 and 109: Fonner tirtal flats with saltmarsh
Page 110 and 111: Grevelingen. Lake Veere and Krammer
Page 112 and 113: As mentioned above aa important que
Page 114 and 115: A seaond important perspective for
Page 116: BEEEXNX, W.D. and 80ZBf&. J. L9M. T
Page 119 and 120: are determining the dfstrlbution af
Page 121 and 122: this volume or in Duutsaa, et aL, 1
Page 123 and 124: artificial waterflow was created af
Page 125 and 126: of waterbirds occur regulsrly. The
Page 127 and 128: . DISTRIBUXIOBI OF WATEJBIRoS OVER
Page 129 and 130: small bird$ 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: scmthem bottueary o-f the winter di
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
Page 168 and 169: 25. The relation between water quan
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Hydro-ecological relations in the Delta Waters

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