Hydro-ecological relations in the Delta Waters

More documents

Recommendations

Info

period 1980-19$3 in an increase of the anaerobic sed-t suzface area of 4 ta 258 of she entire bottom awfkce (Stronlrhorst. et al. 1985). Qbvioualy, the Veerse Meer is vulnerable to eutreghicatian, owing to the long resid&&e the of water msses, the low extinetian coefficient and the ;Umost permanent stratification. The Oastesschelde estuary has a very low N-lead re6nlting in low chlorophyl concentratisne (Table 2). Wing to the execwtina af the Deltaplan (Pig. 1) the Oostarnehelde estuary has mainly been depriVed recently from its Bhinewater loading (Table 1). Model calculations revealed that a reduction of 50% of the nitrosen bed of the river W e would only lead to a rsduetian of less than 6% for nitrogen eoneentratlons in the 0oster.jkbelde estuary (Smobs-swdel; X. Scholten, peraerial co~u~ication). The Uoster~ohelde estuary is rnainly ir;fluenced by tearhe foastalwffter, containing low conewtrations of total nrtrogen (less than 0.5 slg N 1-l; Srockolano, et al. 1988). Contkaq to the Veerse Meer lag~an. the Creveliagen lagoon has an -2 -1 e%treaely Low N-load (4 g N m y ; Table 2). The CaeWA~mdel (De Vries, et al. 19BEI) revealed that Khe prodtlrcim of phytop.lanktan La the Gzevelingen is liodted by nitrogerl availability and not by light availability. The hl : P ratio of tae dlsselved nufkiems in cke watercolm of the GrwsMngenmeer durins winter is 2-4, poirtcing into the direction of a large surplus af phosphate, notwithstanding Che dominance of nitrogen in the discharge utatet, loading the lagoon Eff : P = 22 : I f. Model calculations showed s Mgh tunrover of ni~rog.~u, in the watercolumn. The chain of processes: nutrient uptake by phpoplanktaa - forslation d organic matter in algal cells - mherallzation of dead algae - regeneratbn of nutrients etc.. occurs 8 tWs a year. &out 90X of the anme1 prisary pr&uction of phytoplanktoa occurs on the baeis of resewrated nutrients, especialLy NB4 CDe Vtim, et al. lS88).
In the GZ3WQ-model ~alculatians CDe VrieB, et al, 19881 it is hypotkerriaed that in the Grevelingen lagoon the process of eutra@ication is prevented by the rate of the denitiificatian process. Dnnit-rifioation is undoubtedly a significant process in marine and estuarine ecaqstems. Rates of gaseous losses af nitr-en in the range -2 -1 of 5-70 mg N m d were determined in Bebgi-an, Dutch and Danish caastsl sedimnts, representing 8-23% of tha amount of nirrwen dnerdtliration in the benthic subaystein Caillen and Lancelot, 1987). Notwithstanding the Eaet that no actual measurements exist on denirrification rates in the Grevelingemeer, it is assumed in the OReWQ-model that deeitrificatiw compensates the load of nitrogen, especially in the benthic bonndary layer in the sedismnr, where aerobic and anaerobic 'patches' o;f sediment join each other. In mahp sballw estuarine waters the nain Foed chain ia dpminated by phyto~laakron and bmthir Eilterf eeders (mussels. cockles) , Just as ie the case in the Greoelingenmeer, Oosterschalde and Wadden Sea. T3e rumover rate sf nutrients in these ecosystems is deteraELned bp the filtering capacity of bsnthic filterfeeders. Theoretieally, every 5 to 10 days the entire valme of water of the estuaries circulates through the filtering apparatus of suspension feeders. Filterfeedem act as natuzal cantrollers of the eutrophicatian psocess (Office, et al. 1982): they deposit organic material from the watercolmn Dntn the bottom mdiments. Mnreover, they accelerate the regeneration of nutrients from the deposited perticulate o~anicarbon, thereby enhancing the primary produetion of pbytopLimktun, as was assuxned for the @xevali~enmeer (De Vries, et al. l$&%) 'be chain of pzoeesses - parcly measered. partly cheureticel - from biode~osition to reaenesation of nutrients and the coupling between nitrification and denicr%£icatie$n is limited by the load of szgani~ nace~ial ro t&e sediment. men the increaeing load of ozgulic material runs faster t4w Ehe grocess of heaerotrophic lotneralization. anaerobic cQndFeions wlll prevail in the sediment leading to death of bottom Fauna and a disconnection BE nitrification and dea5trification. GREWAQ- .
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 and 28: prevention measures are desirable h
Page 29 and 30: elationships between different spec
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 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
show all

Hydro-ecological relations in the Delta Waters

You also want an ePaper? Increase the reach of your titles

Delete template?

Save as template?