Hydro-ecological relations in the Delta Waters

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Figure 8 Cadmium content in the gills of Anadonta anatina found at several places in the Raringvliet (a) and the Rallands Diep (b) level had decreased to about the same value as that nomally found in the upstream areas of the Rhine. Nevertheless, the level in eels from the Haringvliet basin is still above the recommended Limit specified for human consumption. To give another example, table 1 shaws BGB levels measured from the Haringvliet basin and some cZean referenee areas. The accumulation is clearly discernihle, The amount of contaminants in plant and animal tissues does not throw very much light on the functioning of the ecosystem. Pollution map be regarded as a form of strees imposed upon the environment. Its effects vary from species to species and may manifest themselves in stunted growth, a fall in the reproduction rate and an increased morrality rate. Given tbat certain animal species are more vulqerahle to pollution than others, it may lead ro shifts in the competitive
elationships between different species. The more vulnerable species will decline and finally disappear, while the less vulnerable species will becm established or increase in particular areas. In general, the total number of species wtll decline, thus impoverishing the ecosystem, poasihly to a severe degree. In the Earingvliet basin the levels are so high that specific environmental effects are to be expected. Inventories carried out in the area have sbwn that the ecosystem in the Eollands Diep is functiot&~g much better than that of the Earingvliet. For instance, the biomass of fauna found on the river bed has been shown 50 be higher in the Hollands Diep. This also applies to the number of fish and to the numher of birds that feed on fish and fauna, living on the river bed, such as cormorants, grebes and tufted ducks (BoudetPijn, et .l, 1986). The differences observed between the Eollands Diep and the Earingvliet may be explained partly in terms of the difference in quality of Ehe beds. But even, the ecosystem qf the Hollan& Diep is poorly developed by compaison with ether large freshwater systems in the Netherlands. Ror exantple, large water plants are scarce in the whole area, even though slight increases have been detected aver the last few years. As far as iudividual species are concerned, sme of the effects are probably connected with the contamination of the river bed. A liak has been est&lished between deviations in the chitin structure of the head of chironomid larvae and the degree of pollution found in the sediment. Lahoratory research hae indicated that the reproduction rate of tufted ducks fed on freshwater mussels from the Haringvliet is considerable lower than that of tufted ducks fed on mussels from less pollated areas (Marquenie, et al. 1987). Moreover, the eggs of tufted ducks and grehes from the Earingvliet area appear to have mueh higher levels of organia micropollutants than those of birds from less contaminated reference areas (Table 1).
Page 1 and 2: Netherlands organkation fw applied
Page 4 and 5: TNO Commlitee on Hydrological Resea
Page 6 and 7: 2 RIVER WATER AM) THE QPALITH OF TB
Page 8: B.J.M. Baptist BIJkswaterstaat. Tid
Page 11 and 12: This approach will put to use what
Page 13 and 14: Estuaries that have not been influe
Page 15 and 16: 2 CHIWGES XN TEE DELTA The Delta ar
Page 17 and 18: area decltned cnnside~ably, leadins
Page 19 and 20: Plan, then it is apparent tbt the s
Page 21 and 22: Tiddl flats df the Eastem Seheldt v
Page 23 and 24: tracefore possible to convert the a
Page 25 and 26: Figsrlre 7 Changes in the cadrnrum
Page 27: prevention measures are desirable h
Page 31 and 32: Bio-essay Weriments with polluted s
Page 33 and 34: considerable thought to drawing up
Page 35 and 36: ShLOUONS, W. and BYSINK, W.D., 1981
Page 37 and 38: are taken. The first year after the
Page 39 and 40: The Hollands DiepJnaringpllet is pa
Page 41 and 42: In 1976 the determination of chlozo
Page 43 and 44: , 0.66 m 0,s - 0.02 1989 I 0.86 - 0
Page 45 and 46: Table 3 Eutrophication of the Volke
Page 47 and 48: Laks Volkarek ---- Lake Zoom 0.40 0
Page 49 and 50: 4 WAGBEET MEdSIIRaS TO PEEVBT OR LT
Page 51 and 52: Table 5 gives estimtes of the phosp
Page 53 and 54: In principle, two states of equilib
Page 55 and 56: Zooplankton (Alma affinis) Pike (Es
Page 58 and 59: EUTROPHICATION OF ESTUAAIES AND BRA
Page 60 and 61: The average discharge of Xhine and
Page 62 and 63: and only l-2% cows frm the aive Sch
Page 64 and 65: highest trophic potential: nutrient
Page 66 and 67: period 1980-19$3 in an increase of
Page 68 and 69: model calculations reveal that a ni
Page 70 and 71: Table 3 PreUmInary carbon budget of
Page 72 and 73: Water life of Lake Grevelingen
Page 74 and 75: macrophytes livkg on or rooting in
Page 76 and 77: less predictable for water managers
Page 78 and 79:
ILWNEWIJK, A.. KEIP, C., 1988. De v
Page 80 and 81:
XBE CHANGING TmAL LAMXiCAPE I N TEE
Page 82 and 83:
The storm surke of L&Z1 A.D., knorm
Page 84 and 85:
osi* rn@8IOIP m .SL 4 Has F~~ULB 3
Page 86 and 87:
During the 19th century man starts
Page 88 and 89:
mudflats have retreated some 100-20
Page 90 and 91:
aq811~33a.e~ pue 3pTatlJS uxaJsafi
Page 92 and 93:
Erosion by waves of sandy shoals (c
Page 94 and 95:
Lt has been estimated that the sedi
Page 96 and 97:
Implementafion of the Delta Project
Page 98 and 99:
ECOLOGICAL DEVELOWdENT OF SALT MAKS
Page 100 and 101:
fn tidal water systems sedimentatio
Page 102 and 103:
hierarchical position. Tn the egtua
Page 104 and 105:
Of course. tke environmental change
Page 106 and 107:
wind erasson, desaliuation, aeratio
Page 108 and 109:
Fonner tirtal flats with saltmarsh
Page 110 and 111:
Grevelingen. Lake Veere and Krammer
Page 112 and 113:
As mentioned above aa important que
Page 114 and 115:
A seaond important perspective for
Page 116:
BEEEXNX, W.D. and 80ZBf&. J. L9M. T
Page 119 and 120:
are determining the dfstrlbution af
Page 121 and 122:
this volume or in Duutsaa, et aL, 1
Page 123 and 124:
artificial waterflow was created af
Page 125 and 126:
of waterbirds occur regulsrly. The
Page 127 and 128:
. DISTRIBUXIOBI OF WATEJBIRoS OVER
Page 129 and 130:
small bird$ 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 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
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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