EUTROPHICATION OF
SURFACE WATERS
IN THE DUTCH
POLDER LANDSCAPE
EUTROPHICATION OF
SURFACE WATERS IN THE
\ ^ JÏ ** DUTCH POLDER LANDSCAPE
EUTROPHICATION OF
SURFACE WATERS IN THE
DUTCH POLDER LANDSCAPE
PROEFSCHRIFT
ter verkrijging van de graad van doctor aan de Technische Universiteit Delft, op gezag van de Rector Magnificus, Prof. Dr. J. M. Dirken, in het openbaar te verdedigen ten overstaan van een commissie aangewezen door het college
van Dekanen, op 23 juni 1988 te 14.00 uur
door
SJOERD PIETER KLAPWIJK
geboren te Sappemeer, doctorandus in de Wiskunde en Natuurwetenschappen
1988
HOOGHEEMRAADSCHAP VAN RIJNLAND LEIDEN
Dit proefschrift is g o e d g e k e u r d door de promotor Prof. Dr. M. Donze.
PROMOTIECOMMISSIE :
Plv. Rector Magnificus: Prof. D r s . P . J . van der Berg Promotor : P r o f . D r . M. Donze
Overige leden : P r o f . D r . I r . J . C . van Dam
(Technische Universiteit Delft) : P r o f . I r . J . H . Kop
(Technische Universiteit Delft) : P r o f . D r . W.H.O. Ernst
(Vrije Universiteit Amsterdam) : P r o f . D r . M. Vroman
(Vrije Universiteit Amsterdam) Gasten : Dr. R.M.M. Roijackers
(Landbouwuniversiteit Wageningen) : Dr. P . J . R . de Vries
STELLINGEN
1. De stelling van Schmidt-van Dorp, dat "niet is aangetoond, dat de toename van de eutrofiëring van het Nederlandse o p p e r v l a k t e water, die in de laatste decennia plaatsvond, veroorzaakt is door een g r o t e r e fosfaattoevoer aan het water", wordt door historische gegevens tegengesproken.
Stelling bij A . D . Schmidt-van Dorp, 1978. De eutrofië r i n g van ondiepe meren in Rijnland (Holland). Proef schrift R . U . Utrecht.
Dit proefschrift.
2. Chemische extractiemethoden k u n n e n bioassays met sediment niet v e r v a n g e n om h e t voor algen beschikbaar sedimentfosfaat te b e palen .
Dit proefschrift.
3. Ten onrechte menen Riegman en Mur dat opnamekinetiek-experi menten defintief uitsluitsel geven over de aard van de n u t r i ë n t -limitatie van de natuurlijke fytoplanktonpopulatie.
R. Riegman & L.R. Mur, 1986. Phytoplankton growth and phosphate uptake (for P limitation) by n a t u r a l phytoplankton populations from the Loosdrecht lakes ( T h e N e t h e r l a n d s ) . Limnol. Oceanogr. 3 1 : 983-988. Dit proefschrift.
4. Voor een grootschalige en effectieve bestrijding van de eutrofië r i n g in het westen van Nederland moet het fosfaatgehalte in de Rijn niet met de helft maar tot minder dan een kwart worden t e r u g g e b r a c h t . Verder dient, naast h e t verwijderen van fosfaten op zuiveringsinstallaties, de fosfaatuitstoot uit de land- en tuinbouw drastisch te worden verminderd.
Aktionsprogramm "Rhein", 1987. Internationale Kommis-sion zum Schutze des Rheins gegen V e r u n r e i n i g u n g , S t r a s s b u r g .
Notitie Fosfaatbeperkende maatregelen Nederlandse op pervlaktewateren. Tweede Kamer, vergaderjaar 1987-1988, 20342, n r . 2.
Dit proefschrift.
5. De aanwezigheid van het pigment chorofyl-b bij de in zakpijpen levende Prochloron didemni R.A. Lewin en de door B u r g e r W i e r s -ma et al. in de Loosdrechtse plassen gevonden draadalg hoeft niet te betekenen dat beide organismen fylogenetisch nauw v e r want zijn.
T. Burger-Wiersma, M. Veenhuis, H . J . K o r t h a l s , C.C.M. van de Wiel & L . R . Mur, 1986. A new p r o k a r y o t e containing chlorophylls a and b . Nature 320: 262-264.
6. Het is onjuist om in het laboratorium aangetoonde effecten van lage zuurstofgehalten op eieren en larven van vissen zonder meer te vertalen naar absolute normen voor het minimum zuurstofge halte in oppervlaktewater g e d u r e n d e het gehele jaar.
J . S . Alabaster & R. Lloyd, 1980. Water quality criteria for freshwater fish. B u t t e r w o r t h s , London.
Indicatief Meerjaren Programma Water 1985-1989. Tweede Kamer, vergaderjaar 1984-1985, 19153, n r . 2. 7. In veel polders in het westen van ons land wordt meer organi
sche stof geproduceerd door kroos en kroosvaren dan door de mens.
8. De aanleg van drinkwaterleiding heeft op veel plaatsen in ons land geleid tot een s t e r k e a c h t e r u i t g a n g in de kwaliteit van het oppervlaktewater.
H. van Zon, 1986. Een zeer onfrisse geschiedenis. Studies over niet-industriële vervuiling in Nederland, 1850-1920. Proefschrift R . U . Groningen.
S . P . Klapwijk & C . J . Smit, 1988. Gouda en de water kwaliteit van Rijnland. In: Ludy Giebels ( r e d . ) : Water beweging rond Gouda van ca. 1100 tot heden: geschie denis van Rijnlands waterstaat tussen IJssel en Gouwe, Leiden.
9. De filosofie van voortschrijdende normstelling, neergelegd in h e t IMP-Milieubeheer, waarbij normen steeds moeten worden v e r s c h e r p t om d r u k op de sanering te houden, werkt ontmoedigend voor degenen die de saneringsmaatregelen moeten uitvoeren en bekostigen en heeft daardoor een a v e r e c h t s effect.
Indicatief Meerjaren Programma Milieubeheer 1986-1990. Tweede Kamer, vergaderjaar 1985-1986, 19204, n r . 2.
10. De complexiteit van de voorgestelde s t r u c t u u r voor normering van waterbodems maakt dat men de daaruit voortvloeiende normen voorlopig het beste naast zich neer kan leggen.
Interimrapport van de werkgroep Normering, 1986. Onderwaterbodem overleg RWS-DGMH.
11. Ten behoeve van de zogenaamde multifunctionele bodemkwaliteit ware het b e t e r volkstuinen te gebruiken als referentie in plaats van veldgegevens uit landelijke gebieden en als schoon beschouw de waterbodems.
Voortgangsrapportage Milieuprogramma 1988-1991. Tweede Kamer, vergaderjaar 1987-1988, 20202, n r . 2. 12. Om beleidsmakers, b e s t u u r d e r s en politici er van te doordringen
dat zeer lage fosfaatgehalten nodig zijn om de algengroei te b e p e r k e n , verdient het aanbeveling om fosfaatconcentraties voortaan in microgrammen in plaats van in milligrammen uit te d r u k k e n .
13. Het aanprijzen van fosfaatvrije wasmiddelen met het toevoegsel "Groen" lijkt op anti-reclame.
14. Het uitzetten van g r a s k a r p e r s zou vergunningsplichtig moeten zijn in het kader van de Wet verontreiniging oppervlaktewateren. 15. Als waterschappen een v o o r t r e k k e r s r o l moeten gaan vervullen bij
integraal w a t e r b e h e e r , zal h u n politieke basis moeten worden v e r b r e e d .
Naar een samenhangend oppervlaktewaterbeheer, 1987. Unie van Waterschappen, ' s - G r a v e n h a g e .
16. Gezond b o e r e n v e r s t a n d vormt de k r a c h t èn de zwakte van het waterschapsbestel.
17. De stormvloedkering in de Oosterschelde laat zien dat w a t e r s t a a t kundige ( k u s t ) w e r k e n geen kunstwerken maar -soms- kunstige werken zijn.
18. Alleen al om bibliografische redenen kunnen vrouwelijke a u t e u r s b e t e r onder hun eigen naam en niet onder die van hun echtge noot publiceren.
19. De gewoonte om bij echtscheidingen niet alleen de boedel maar ook de ouderlijke macht te scheiden is vaak niet in het belang van de k i n d e r e n , de ouders en de gemeenschap.
20. Bij alle rechten aan de doctorstitel verbonden behoort blijkens het promotieprotocol van de T . U . Delft ook de plicht voor de pas gepromoveerde om aan het slot van de promotieplechtigheid niets t e r u g te zeggen. Dit staat in te schril contrast met de verwach ting bij de daaraan voorafgaande verdediging van h e t proef schrift .
Stellingen behorende bij het proefschrift "Eutrophication of surface waters in the Dutch polder landscape".
Aan mijn vader
d s . P. Klapwijk (1906-1972) Voor Floor
CIP-DATA Koninklijke Bibliotheek, Den Haag Klapwijk, Sjoerd Pieter
Eutrophication of surface waters in the Dutch polder landscape / Sjoerd Pieter Klapwijk ; [ill. Anne Post toe Slooten]. - Leiden : Hoogheemraadschap van Rijnland. - 111.
Thesis Delft. - With ref. - With summary in Dutch. ISBN 90-72381-02-5
SISO 568 UDC 504.45.058(492)(043.3)
Subject heading: eutrophication ; surface waters ; The Netherlands.
-7-CONTENTS Chapter Page 1. General introduction 9 PART A: PHYTOPLANKTON 17 2. Introduction phytoplankton 19 3. Biological assessment of the water quality in South Holland
(The Netherlands) 23 4. Comparison of historical and recent data on hydrochemistry
and phytoplankton in the Rijnland area (The N e t h e r l a n d s ) 59 5. Dose-effect relationships between phosphorus concentration
and phytoplankton biomass in the Reeuwijk Lakes (The
Netherlands) 83 PART B: SEDIMENTS 91
6. Introduction sediments 93 7. Available phosphorus in lake sediments in the Netherlands 99
8. Application of derivative spectroscopy in bioassays estima
ting algal available phosphate in lake sediments 111 9. Available phosphorus in the sediments of eight lakes in the
Netherlands 119 PART C: BIOASSAYS 129
10. Introduction bioassays 131 11. Effects of phosphorus removal on the maximal algal growth
in bioassay experiments with water from four Dutch lakes 137 12. Algal growth potential tests and limiting n u t r i e n t s in the
Rijnland Waterboard area ( T h e Netherlands) 151 13. Bioassays u s i n g Stigeoclonium tenue Kütz. and Scenedesmus
quadricauda ( T u r p . ) B r é b . as testorganisms; a comparative
study 169 14. Comparison of different methods to determine growth limi
ting factors for phytoplankton in the Reeuwijk Lakes ( T h e
Netherlands) 179 15. Summary and conclusions 203
16. Samenvatting en conclusies 211
Curriculum vitae 220 Publikaties 220 Dankwoord 225 Colofon 227
CHAPTER 1:
GENERAL INTRODUCTION
9
-"Eutrophication, which may be n a t u r a l or man-made, is the response in water to overenrichment by n u t r i e n t s , particularly phosphorus and n i t r o g e n . "
OECD, 1982. Eutrophication of w a t e r s ; monitoring, assessment and control, p . 17. Organisation for Economic Co-operation and Development, P a r i s .
-10-GENERAL INTRODUCTION
Eutrophication, defined by Parma (1980) as "the process in water d u r i n g which the factors stimulating autotrophic production becomes optimal" b u t mostly known as "the overenrichment of surface water with n u t r i e n t s , having s t r o n g impact on abiotic and biotic factors in aquatic ecosystems (algal blooms, anaerobiosis, fish k i l l s ) " , is essen tially a n a t u r a l phenomenon. Naturally the loading of surface waters with n u t r i e n t s happens through erosion, through deposition of animal faeces, as from bird colonies, plant d e b r i s , e t c . In this c e n t u r y the process of eutrophication was accelerated through human activities. The human population increased, the construction of drinking-water and sewage systems led to large-scale discharges of wastewater (van Zon, 1986), agricultural methods changed ( e . g . by the u s e of fertili z e r s and by not recycling all manure) and after 1950 the u s e of phos phate-containing d e t e r g e n t s increased rapidly. As in o t h e r p a r t s of the world (well-known examples are the Great Lakes in North Ame r i c a ) , most lakes in Europe deteriorated, like the Swiss and Italian Alp lakes (Thomas, 1953; Vollen weider, 1968), many East-European lakes ( S t r a s k r a b a & Straskrabova, 1969), the Grosser Plöner See (Ohle, 1955), several Danish lakes ( B e r g et al. , 1958; Johnsen et a l . , 1962) and the previous oligotrophic Swedish lake Trummen (Andersson et a l . , 1973).
The water in the delta of the r i v e r Rhine was probably always moderately rich in n u t r i e n t s the r i v e r imported. The description of dominant phytoplankton species in the Rhine delta from Lauterborn (1918) at the beginning of this c e n t u r y shows t h a t the water was al ready r a t h e r eutrophic t h e n . Peelen (1975) comparing the old plankton data of several investigators with recent observations found that the plankton composition of t h e river Rhine between the beginning of the century and ca. 1973 had changed somewhat, b u t that t h e saprobic level had not moved. However he did find an increase in the amount of plankton organisms, probably caused by increasing eutrophication a n d / o r lengthening of the residence times in the Rhine b r a n c h e s .
In the Netherlands especially Golterman (1965, 1970a,b, 1971, 1972, 1973a,b) called attention to the rapidly increasing eutrophication in the sixties and early seventies. He initiated a special s t e e r i n g com mittee of the Royal Dutch Chemical Society to s t u d y this problem. As a result a r e p o r t was compiled on the causes and consequences of the eutrophication problem in the N e t h e r l a n d s . It suggested measures to be taken to reduce the phosphate-loading of the Dutch, surface waters (Golterman, 1976). This study gave occasion to the so-called "Fosfa-tennota" (Phosphate Report) in 1979 by the ministries of Public Health & Environmental Hygiene and Public T r a n s p o r t & Public Works (1979), explaining the governmental policy concerning eutrophication control. It stated that the reduction of the phoshate levels had to b e achieved by phosphate-removal at sewage treatment plants and by replacement of phosphates in d e t e r g e n t s .
In the Rijnland waterboard area the eutrophication problem has been studied from 1973-1976 by Schmidt-van Dorp (1975, 1978), who found t h a t due to the high levels of total and inorganic phosphate in most of the lakes phosphorus was not a limiting n u t r i e n t for algal growth any more. She suggested that in this area more attention should be paid to nitrogen reduction. Nevertheless it was generally
-1.1-concluded (Klapwijk, 1977; Hosper, 1978; Golterman, 1979) t h a t e u t r o phication could be b e t t e r combatted by Preduction than by N r e d u c -tion for the following r e a s o n s , as indicated in the postscriptum ( p . 241-242) to Schmidt-van Dorp (1978):
1. Nitrogen is discharged more diffuse than phosphate e . g . by a g r i c u l t u r e . It is therefore more difficult to control.
2. In nearly all surface waters nitrogen-fixing blue-green algae oc c u r , capable to use free nitrogen for their growth.
It was feared that N-reduction would stimulate a change from nonfixing b l u e - g r e e n s to nitrogen fixing b l u e - g r e e n algae, which is also confirmed by laboratory experiments. This would not contribute v e r y much to the solution of the eutrophication problem. Moreover, it should always be kept in mind that nitrogen has become the primary limiting n u t r i e n t in surface waters because the phosphorus load has relatively more increased than the nitrogen load (Thomas, 1953). It seems more sensible to reduce the n u t r i e n t which is relatively most increased by human activities.
Therefore the Waterboard of Rijnland carried out a large-scale phosphate-removal experiment at t h r e e sewage treatment plants (Gouda, Bodegraven and Nieuwveen) from 1979 to 1982 in o r d e r to reduce eutrophication in the lakes in the s o u t h - e a s t of its area (Klap wijk, 1977). Because of the complexity of the eutrophication problem, extensive limnological research was accompanying this experiment to monitor the effects of phosphate-removal at the t h r e e sewage treat-1 ment plants (Klapwijk, 1981; Hoogheemraadschap van Rijnland, 1984; van der Does & Klapwijk, 1985, 1987). P a r t s of this research are en closed in this thesis (Chapters 7, 8, 9 and 11).
Since it had to be concluded from this experiment that p h o s p h a t e -removal at sewage treatment plants will not lead to an immediate de crease of algal biomass in the l a k e s , which form p a r t of the basin system of Rijnland, later the attention has been focussed on the more isolated polder lakes in which the execution of complete p h o s p h o r u s reduction measures can be more rigorous and might be more effective. Therefore lake restoration projects have been developed for the Reeu-wijk, the Nieuwkoop and the Langeraar lakes ( G e e r p l a s ) , in which all phosphate sources will be reduced simultaneously.
The Reeuwijk lakes were studied from 1983-1985 to collect back ground information on the water quality in the lakes. Parts of this investigation are p r e s e n t e d in the C h a p t e r s 5 and 14 (cf. van der Vlugt et a l . , 1986; van der Vlugt & Klapwijk, 1987). Phosphate-remo val was started at the local sewage treatment plant of the village of Reeuwijk in 1986. So far, no clear r e s u l t s have appeared. As supple mentary measures fish population management and in-lake treatment with a precipitant will be carried out in p a r t s of the lakes. For the Nieuwkoop lakes area a complex project has been developed including among others the diminution of water t r a n s i t , separation of the a g r i cultural p a r t from the lakes, and dephosphating of the intake water. For the Geerplas project the following measures are planned: isolation of the Geerplas of the remaining Langeraar lakes, dredging of the u p p e r phosphate-rich sediment layer, dephosphating of the intake water and polishing of this water by a macrophyte-swamp.
-12-This thesis deals with the eutrophication research carried out from 1977-1987 at the Rijnland Waterboard laboratory. It consists of three p a r t s :
Part A deals with phytoplankton, especially its use in assessing water quality in an ecological way ( C h a p t e r 3 ) , while in Chapter 4 a comparison is made between historical and recent phytoplankton and chemical data with the intention to find ecological objectives for com batting eutrophication. In Chapter 5 a description of the phosphate-phytoplankton relationships in the Reeuwijk lakes is p r e s e n t e d .
Part B is focussed on sediments, especially the availability of s e diment phosphates for algal growth. This availability is determined in four lakes with a bioassay technique and compared with two chemical extraction techniques ( C h a p t e r 7 ) , while in Chapter 8 a new method is proposed, which is applied to the sediments of eight lakes in the Rijnland area ( C h a p t e r 9 ) .
Part C t r e a t s bioassays, which are used to assess the algal growth potential and to determine the limiting n u t r i e n t ( s ) for algal growth in lakes and canals. This is done with the aid of the indige nous phytoplankton population (Chapter 11) and with testalgae like Scenedesmus quadricauda (Chapter 12). In Chapter 13 bioassays with two different testalgae and with different procedures are compared, while in Chapter 14 a comparison is made between two bioassay tech niques and several o t h e r methods to assess growth limiting factors in the Reeuwijk l a k e s .
In this thesis the policy development of the Rijnland Waterboard with respect to the eutrophication problem in the last ten years is also recognizable. In the first instance the attention was directed to the assessment of the water quality and the sediments (Chapters 3 , 7, 8, 9 ) , followed by large-scale phosphate-removal at sewage t r e a t ment plants ( C h a p t e r 11). Since these source-directed measures did not lead to r e s u l t s , the policy has been changed in a water quality approach of specific lakes ( C h a p t e r s 5, 12, 14). Based on the r e search described in this thesis lake restoration projects could be d e veloped for the Reeuwijk, the Nieuwkoop and the Langeraar lakes, which are being carried out now.
Research is often a cooperative effort as is a p p a r e n t from the fact t h a t scientific p a p e r s are seldom written by one author. In this thesis Chapters 5, 8, 11 and 13 are written in the first instance by collegues in cooperation and responsibility with this author. Chapters 7, 9, 12 and 14 are mainly written by me with support by several co a u t h o r s . The remaining Chapters 1, 2, 3, 4, 6, 10, 15 and 16 are entirely my responsibility.
REFERENCES
Andersson, G . , G. Cronberg & C. Gelin, 1973.
Planktonic changes following the restoration of lake Trummen, Sweden. Ambio 2: 44-47.
Berg, L . K . , K. A n d e r s e n , T . Christensen et a l . , 1958.
Fures0 u n d e r s ö g e l s e r 1950-1954. Folia Limnologica Scandinavica 10: 1-189.
1 3
-Does, J . van der & S.P. Klapwijk, 1985.
Phosphorus removal and effects on waterquality in Rijnland. H20 18: 381-387 (in Dutch with an English summary).
Does, J . van der & S . P . Klapwijk, 1987.
Effects of phosphorus removal on the maximal algal growth in bioassay experiments with water from four Dutch l a k e s . Int. Revue g e s . Hydrobiol. 72: 27-39.
Golterman, H . L . , 1965.
Hydrobiologische aspecten van de Vechtplassen. Akademiedagen 17: 23-36.
Golterman, H . L . , 1970a.
Eventual consequences of the phosphate-eutrophication of fresh water. H20 3: 209-215 (in Dutch with an English summary). Golterman, H . L . , 1970b.
De invloed van het menselijk handelen op de biocoenosen in het water. In: Biosfeer en Mens, p . 80-103. Pudoc, Wageningen. Golterman, H . L . , 1971.
De vervanging van polyfosfaten in wasmiddelen door NTA. H20 4: 557-559.
Golterman, H . L . , 1972.
De zegepralende Vecht. H20 5: 33-34. Golterman, H . L . , 1973a.
The influence of phosphate on aquatic life. H20 6: 430-438 (in Dutch with an English summary).
Golterman, H. L. , 1973b.
Natural phosphate sources in relation to phosphate b u d g e t s : A contribution to the u n d e r s t a n d i n g of eutrophication. Water Res. 7: 3-17.
Golterman, H.L. ( e d . ) , 1976.
Fosfaten in het Nederlandse oppervlaktewater. Rapport van de 'Stuurgroep Fosfaten' van de K . N . C V . Sigma Chemie.
Golterman, H.L. , 1979.
Removal of phosphate from sewage w a t e r s ; the only possible mea sure to decrease algal blooms, even in the lakes in Rijnland. H20 12: 40-44 (in Dutch with an English summary).
Hoogheemraadschap van Rijnland, 1984.
Rapport betreffende het onderzoek naar de effecten van fosfaat verwijdering op de a . w . z . i . ' s Gouda, Bodegraven en Nieuwveen. Rapport technische dienst van Rijnland, Leiden.
Hosper, S . H . , 1978.
Nitrogen, phosphorus and eutrophication. H20 11: 385-387 (in Dutch with an English summary).
-14-J o h n s e n , P . , H. Mathiesen & U. Rtfen, 1962.
The Sor0 lakes, lake Lyngby S0 and lake Bagsvaerd S0, limnoli-gical studies in five culturally influenced lakes in Sjaelland (Zea l a n d ) . Dansk Ingeni0rforening, Spildevandskorn. 14: 1-135. Klapwijk, S . P . , 1977.
Experimentele fosfaatverwijdering op praktijkschaal in Rijnland. Waterschapsbelangen 62: 284-289.
Klapwijk, S.P. , 1981.
Limnological research on the effects of phosphate removal in Rijnland. H20 14: 472-483 (in Dutch with an English summary). L a u t e r b o r n , R . , 1918.
Die geographische und biologische Gliederung des Rheinstroms. Teil III. S i t z u n g s b e r . Heidelberg. Akad. Wissensch. , Math. - n a t . Klasse Abt. B, 1918: 1-87.
Ministries of Public Health & Environmental Hygiene and Public T r a n s p o r t & Public Works, 1979.
Fosfatennota: Maatregelen voor het t e r u g d r i n g e n van de fosfaat belasting van het Nederlandse oppervlaktewater. Staatsuitgeverij, ' s - G r a v e n h a g e .
Ohle, W., 1955.
Die Ursachen der rasanten Seeneutrophierung. Verh. i n t e r n a t . Ver. Limnol. 12: 373-382.
Parma, S. , 1980.
The history of the eutrophication concept and the eutrophication in the Netherlands. Hydrobiol. Bull. 14: 5-11.
Peelen, R. , 1975.
Changes in the composition of the plankton of the r i v e r s Rhine and Meuse in the Netherlands during the last fifty-five y e a r s . Verh. i n t e r n a t . Verein. Limnol. 19: 1997-2009.
Schmidt-van Dorp, A . D . , 1975.
Phosphate and eutrophication in the Waterboard of Rhineland. H20 8: 254-258 (in Dutch with an English summary).
Schmidt-van Dorp, A . D . , 1978.
Eutrophication of shallow lakes in Rijnland. Report Technical Service, Hoogheemraadschap van Rijnland, Leiden (in Dutch with an English summary).
S t r a s k r a b a , M. & V. S t r a s k r a b o v a , 1969.
Eastern European Lakes. In: Eutrophication: causes, consequen ces, correctives, p . 65-97. Proc. Symp. Nat. Acad. Sci. Was hington, D . C . , 1969.
Thomas, E . A . , 1953.
Zur Bekampfung der See-Eutrophierung: Empirische und experi-mentelle Untersuchungen zur Kenntnis der Minimum stoffen in 46 Seen der Schweiz und a n g r e n z e n d e r Gebiete. Schweiz. Ver. Gas-Wasserfachm. Monatsbull. 33: 25-32; 71-79.
1 5 -Vollenweider, R . A . , 1968.
Scientific fundamentals of the eutrophication of lakes and flowing w a t e r s , with particular reference to nitrogen and phosphorus as factors in eutrophication. OECD-report, Paris.
Vlugt, J . C . van d e r , S . P . Klapwijk & J.A.A.M. van Eijk, 1986.
Waterkwaliteitsonderzoek Reeuwijkse plassen WOR 1983-1985. Report n r . 840156001 National Institute for Public Health and Environmental Hygiene, Bilthoven.
Vlugt, J . C . van d e r & S . P . Klapwijk, 1987.
Water quality research in the Reeuwijk lakes 1983-1985. H20 20: 86-91 (in Dutch with an English summary).
Zon, H. v a n , 1986.
A v e r y d i r t y affair - Studies in non-in dus trial pollution in the Netherlands, 1850-1920. Ph. D . Thesis, Univ. Groningen (in Dutch with an English summary).
-
16-Foto p a g . 17: Massaal voorkomen van draadvormige blauwalgen in het fytoplankton v a n de Nieuwkoopse plassen (Noordeinder-plas d . d . 30.03.88).
PART A: PHYTOPLANKTON
/ Ï * * ^
\ j
.//—{ V/
\ - /-19-CHAPTER 2:
INTRODUCTION PHYTOPLANKTON
"Intusschen is h e t e c h t e r gebleken, dat de samenstelling van het wa t e r zoodanig inwerkt op de planten en dieren, die er in leven, dat in de ontwikkeling, die zij vertoonen, niet alleen de gevolgen van cata-strophale veranderingen tot u i t d r u k k i n g komen, maar dat ook minder acuut verloopende veranderingen in de samenstelling van het water hierop onmiskenbare gevolgen teweeg b r e n g e n . "
G. Romijn, 1924. Hydrobiologische toestand van Rijnland. V e r slagen en mededelingen betreffende de Volksgezondheid, no. 2, p . 110.
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-INTRODUCTION PHYTOPLANKTON
Eutrophication in surface waters is most often e x p r e s s e d in an increase in phytoplankton biomass, resulting sometimes in severe algal blooms (Golterman, 1975, 1976; Parma, 1980; Barica & Mur, 1980). Not only the algal biomass is increasing, the algal species composition changes too as a result of eutrophication. Phytoplankton assemblages rich in species from different groups ( e . g . diatoms, green algae and flagellates) disappear and blue-green algae begin to dominate the plankton association.
• Not only eutrophication, but other factors, e . g . the intensity of supply of organic matter and the speciation of chemical elements, in fluences phytoplankton composition and abundance also. The species composition reflects the different conditions in the water and can therefore be used to assess the water quality of surface w a t e r s . Kolk-witz and Marsson (1902) developed a saprobity system t h a t is based on the presence of species and that is appropriate for classifying the impact of organic pollution in r u n n i n g w a t e r s . This system is later extended by Liebmann (1960-1962) and Sladecek (1963, 1973).
About twenty years ago Caspers & Karbe (1966, 1967) presented a water quality system based on physiological and ecological views, that tried to combine the leading concepts on saprobity and trophism. They showed that both are running parallelly (Caspers & Karbe, 1966, 1967; C a s p e r s , 1977; Sladecek, 1973). This was and still is im portant to the practical water management in the western part of the Netherlands, where both phenomena play a leading role in water qua lity. Caspers and Karbe's system seems to be valid at least for stag nant bodies of water (Sladecek, 1973). Applying the system in the Netherlands seemed to be very promising, since most of the Dutch surface waters are s t a g n a n t and the relation between discharges of organic material, causing saprobity, and inorganic material, causing eutrophication, is often very intricate.
Caspers and Karbe (1967) stated that classifying waters in one of their six classes can occur in three separate ways: (1) according to the bioactivity, which means the ratio between the intensity of pri mary production and respiration; (2) according to oxygen regime cri teria, especially the extent of the daily fluctuations and (3) according to the s t r u c t u r e of biological communities in the water, for instance the diversity and biomass of the phytoplankton community and the re lation between p r o d u c e r s , consumers and decomposers. Caspers and
Karbe never worked out their scheme into a system for water quality assessment of specific waters. Therefore, we tried to elaborate their scheme in order to use it for the quality assessment of large stagnant surface waters in the western p a r t of the Netherlands (Chapter 3).
Since phytoplankton compositions reflect very well the physical and chemical conditions in a water, old plankton data can be compared to recent data to see if anything has changed as a consequence of in creasing eutrophication. Therefore, in Chapter 4 a comparison is p r e sented between historical and recent data on water chemistry and phytoplankton in two canals and two lakes in the Rijnland Waterboard area in order to determine the differences and to find realistic objec tives for eutrophication parameters such as chlorophyll-a and transpa rency . The employed historic data set (from 1941 and 1942) is parti cularly interesting since it contains besides qualitative data on phyto plankton composition quantitative data too in addition to several time series of hydrochemical analyses.
2 1
-Finally, in Chapter 5 dose-effect relationships between phospho r u s concentration and phytoplankton biomass are described for the Reeuwijk lakes. The aim of this study was to collect basic information on the water quality in the lakes, which can be compared with possi ble changes o c c u r r i n g when the external p h o s p h o r u s load is r e d u c e d , e . g . by dephosphating at the local sewage treatment plant of Reeuwijk.
REFERENCES
Barica, J . & L . R . Mur ( e d s . ) , 1980.
Hypertrophic ecosystems. Developments in Hydrobiology 2: 1-348. J u n k , The Hague - Boston - London.
C a s p e r s , H . , 1977.
Qualitat des Wassers - Qualitat der Gewasser. Die Problematik der Saprobiensysteme. In: Sladecek, V . , 1977 ( e d . ) , Symposium on Saprobiology. Ergebn. Limnol. 9: 3-14.
C a s p e r s , H. & L. Karbe, 1966.
Trophie und Saprobitat als stoffwechsel-dynamischer Komplex. Gesichtspunkte fiir die Definition der S a p r o b i t a t s s t u f e n . Arch. Hydrobiol. 61: 453-470.
C a s p e r s , H. & L. Karbe, 1967.
Vorschlage für eine saprobiologische T y p i s i e r u n g der Gewasser. I n t . Revue g e s . Hydrobiol. 52: 145-162.
Golterman, H . L . , 1975.
Physiological Limnology. Elsevier Scientific Publishing Company, Amsterdam.
Golterman, H . L . ( e d . ) , 1976.
Fosfaten in het Nederlandse oppervlaktewater. Rapport van de s t u u r g r o e p fosfaten van de K . N . C V . Sigma Chemie.
Kolkwitz, R. & M. Marsson, 1902.
Grundsatze für die biologische Beurteilung des Wassers nach seiner Flora und Fauna. Mitt. P r ü f u n g s a n s t . Wasserversorgung. Abwassereinigung 1: 33-72.
Liebmann, H. ( e d . ) , 1960-1962.
Handbuch der Frischwasser- und Abwasserbiologie. Band I & II. R. Oldenbourg, München.
Parma, S . , 1980.
The history of the eutrophication concept and the eutrophication in the N e t h e r l a n d s . Hydrobiol. Buil. 14: 5-11.
Sladecek, V . , 1963.
A guide to limnosaprobical organisms. Science Papers I n s t . Chem. Techn. P r a g u e , Techn. Water 7: 543-612.
Sladecek, V . , 1973.
System of water quality from the biological point of view. Er g e b n . Limnol. 7: 1-218.
2 3
-CHAPTER 3:
BIOLOGICAL ASSESSMENT OF THE WATER QUALITY IN SOUTH HOLLAND (THE NETHERLANDS)
Accepted for publication in: Int. Revue g e s . Hydrobiol.
"The proposal of Caspers & Karbe is no doubt modern, elegant and a t t r a c t i v e , b u t the engineer asks for numbers and how to obtain them. For this reason C a s p e r ' s scheme is more a programme than a functio ning system."
Sladecek, V . , 1973. System of water quality from the biological point of view. E r g e b . Limnol. 7, p . 44.
-24-BIOLOGICAL ASSESSMENT OF THE WATER QUALITY IN SOUTH HOLLAND (THE NETHERLANDS).
Sjoerd P. Klapwijk Key words: biological assessment, water quality, phytoplankton,
biological indicators, s a p r o b i t y , trophism.
ABSTRACT
A hydrobiological study was carried out to elaborate the water quality classification system of Caspers and Karbe (1966, 1967) for the large s t a g n a n t bodies of water in the western part of the Nether lands. Significant correlations have been established between different physical and chemical parameters and phytoplankton community s t r u c t u r e s such as diversity and saprobity. A proposal is developed to quantify the water quality classes in Caspers and Karbe's scheme on parameters measuring the bioactivity, oxygen regime and phytoplank ton community s t r u c t u r e . The scheme is now incorporated in the p r a c tical water quality assessment in North Holland and South Holland both for routine monitoring as well as for special water quality stu dies.
1. INTRODUCTION
Both from a scientific point of view as well as in the applied wa ter management practice classification of waters is useful and necessa ry and is widely applied since the beginning, of this century. Practi cal water management requires preferably a classification system which has a solid scientific base and is simple and cheap to execute. The classic saprobity system developed by Kolkwitz and Marsson (1902) and later extended by Liebmann (1960-1962) and Sladecek (1973) is providing this base on the presence of species and is especially a p propriate for classifying the impact of organic pollution in r u n n i n g waters.
Twenty y e a r s ago Caspers and Karbe p r e s e n t e d a water quality system based on physiological and ecological principles ( C a s p e r s , 1966; Caspers & Karbe, 1966; 1967). This system tried to combine the leading concepts on saprobity and trophism. It was shown that both are r u n n i n g parallelly (Caspers & Karbe, 1966; Caspers, 1977a; Sla decek, 1977). This was and still is important to the practical water management, where both phenomena play a leading role in water qua lity. Essential in the system is also that it combined functional as well as s t r u c t u r a l aspects of the aquatic ecosystem.
Caspers and Karbe's system with six water quality classes seems to be valid at least for stagnant bodies of water (Sladecek, 1973). Applying the system in the Netherlands seemed very promising, since most of the Dutch surface waters are stagnant and the relation be tween discharges of organic material, causing saprobity, and inorga nic material, causing eutrophication, is often very intricate. Caspers and Karbe (1967) stated that classifying waters in one of their six classes can occur in three separate ways (cf. Hovenkamp et a l . , 1982):
Table 1. Scheme of water quality classes according to Caspers & Karbe (Modified after C a s p e r s & K a r b e , 1967 and Sladecek, 1973). Intensity of supply of organic matter negligible Bioactivity Intensity Intensity of of primary respiration production Oxygen regime oxygen c o n t e n t i n d e p e n d e n t of bioacti v i t y , determined by h y d r o g r a p h i c factors S t r u c t u r e of community of organisms Total biomass poor in individuals; moderate d i v e r s i t y T y p e of organisms
balanced relationship between p r o d u c e r s , consu mers and decomposers
oxygen content d e t e r mined more o r less equally by assimila tion, respiration and h y d r o g r a p h i c factors
large rich in individuals; high diversity
balanced relationship between p r o d u c e r s , consu mers and decomposers
high high daily oxygen content shows a distinct dependence upon the activity of organisms; frequently s u p e r s a t u -ration d u r i n g daytime and oxygen deficit at night
rich in individuals; high diversity
substantially balanced relationship between p r o d u c e r s , consumers and decomposers; a relative increase of decomposers and consumers
I I
v e r y high high v e r y high oxygen content usually below the saturation v a l u e ; anaerobic conditions prevail at n i g h t ; variations in the supply of poliutant material a r e clearly recognizable from the oxygen content
large rich in individuals; low diversity
many consumers and decomposers, few p r o d u c e r s ; mass development of bacteria and ciliates
extremely high low extremely high anaerobic conditions predominate even d u r i n g the daytime
large extremely rich in p r o d u c e r s drastically decline; only a few macro-individuals; fauna species are p r e s e n t in g r e a t a b u n d a n c e ; low diversity mass development of bacteria and ciliates VI extremely high a p p r o x . O extremely high permanently anaerobic total biomass is formed practically solely by anaerobic bacteria and fungi;
-26-1. According to the bioactivity, which means the ratio between the primary production and respiration (cf. Odum, 1956 and Slade-cek, 1973).
2. According to oxygen regime criteria, especially the extent of the daily oxygen fluctuations.
3 . According to the s t r u c t u r e of biological communities in the water, for instance the diversity and biomass of the community and the relationship between p r o d u c e r s , consumers and decomposers. Their ideas about the classification into six classes have been summarized in Table 1. Caspers and Karbe never worked out this scheme into a system for water quality assessment of specific waters. As Sladecek (1973) already remarked the scheme is "more a program me than a functioning system". Therefore the aim of this study was to elaborate the scheme in o r d e r to use it for the water quality a s sessment of large stagnant surface waters in the western part of the N e t h e r l a n d s . The s t u d y aimed to find suitable chemical, physical or biological p a r a m e t e r s , which can be used to measure the aspects bio activity (production and r e s p i r a t i o n ) , oxygen regime and community s t r u c t u r e in Caspers and Karbe's scheme in an ecologically based and consistent way. Since the scheme has to be applied in practical water quality management, special emphasis has been paid to the relation between the phytoplankton in the waters and the physical and chemi cal water quality p a r a m e t e r s , which are normally determined in rou tine monitoring p r o g r a m s .
2. MATERIALS AND METHODS
During 1977 and 1978 samples for physical and chemical. water analyses were taken before noon every month at more than sixty sam pling sites at a depth of 0.5 m in six different morphological and hy-drological water types in the province of South-Holland (Table 2). Table 2. Summary of the considered water t y p e s , the number of sam
pled sites and the frequency of sampling.
Water t y p e s Number of sites for
p h y s i c a l and chemical analysis plankton analysis
Canals Lakes Peat l a k e s Deep s a n d p i t s Deep pools Dune lakes Total F r e q u e n c y of p e r y e a r : y e a r : sampling 1977 26 24 13 2 1 0 66 12x 1978 21 26 12 4 2 2 67 12x 1977 6 6 .6 -18 1978 3 5 3 2 2 0 15
2 7
-In 1977 at eighteen and in 1978 at fifteen of the sampling sites also plankton samples were taken respectively five and twelve times p e r y e a r . An extensive description of the sampling method and sampling sites is given by Klapwijk (1982). In this s t u d y 1085 water analyses and 260 plankton analyses were u s e d .
The sampling sites were chosen in such a way that both polluted and unpolluted stations were incorporated in the s t u d y . The following w a t e r analyses were c a r r i e d out according to s t a n d a r d methods of the Netherlands Normalisation I n s t i t u t e : pH, t e m p e r a t u r e , oxygen concen tration ( 02) , oxygen saturation ( 02% ) , chemical oxygen demand
(COD), biological oxygen demand (BOD), Kjeldahl-N, NH4-N, N02+
N 03- N , o r t h o - P , t o t a l - P , Cl , Secchi disk t r a n s p a r e n c y , specific con ductivity and chlorophyll-a ( C H L - a ) .
One liter plankton samples were also taken at 0.5 m d e p t h , t r a n s p o r t e d to the laboratory in glass j a r s , p r e s e r v e d with 10 ml 37% formalin and poured into one liter high measure glasses to let the plankton settle in a quiet and d a r k place. After two to six weeks the supernatant water was siphoned off and t h e settled plankton was b r o u g h t into 80 ml t e s t - t u b e s to settle again. After a few weeks the s u p e r n a t a n t water again was poured off so that the plankton was con centrated in a volume less of than 30 ml. In those samples that con tained many floating b l u e - g r e e n algae ( e . g . Microcystis aeruginosa Kütz) the s u p e r n a t a n t was not discarded but filtrated through a 20 p plankton gauze and the filtrated plankton was added.
Random plankton countings up to at least h u n d r e d individuals or colonies p e r sample were c a r r i e d out on an inverted plankton micro scope (Olympus IMT) with magnification of 40x, lOOx, 200x and 400x u s i n g a 2 cm3 cuvette with a h e i g h t of 2 mm. Every single cell, colo ny of cells or filament is counted as one individual with the exception that ten loose cells of Microcystis aeruginosa were counted as one. Colonies of this species nearly always fell a p a r t by the formalin p r e servation. Remnants of algae or empty cells ( e . g . diatom thecae) were excluded from the c o u n t i n g s .
The phytoplankton species were identified using mainly the keys in Huber-Pestalozzi (1950-1962), Pascher (1913-1930), Prescott (1964), Schroevers ( u n p u b l i s h e d ) , Streble and K r a u t e r (1974), Uherkovitz (1966) and van der Werff and Huls (1957-1974). Apart from the p h y toplankton countings, the number of ciliate species was determined for the quotient of D r e s s c h e r and van der Mark (1976) by concentrating an u n p r e s e r v e d one liter water sample over a 20 p plankton gauze to a small volume (5-10 ml) and counting the number of ciliate species in a few drops of the living concentrate u n d e r a normal microscope (Olympus BHA) with 40x, lOOx, 400x and lOOOx magnification. This microscope was also used to check uncertain identifications made with the inverted microscope and to identify the diatom species in the sam ples by means of separate diatom p r e p a r a t i o n s .
With t h e aid of a DEC PDP 14/34 computer the following ecolo gical characteristics were calculated and derived from the plankton countings.
2 . 1 . Similarity:
Species composition on the sampling sites was compared in two different ways:
-28-a. the qualitative resemblance, based on presence of species on the sampling sites, is computed by the similarity index of Jaccard (Mueller-Dombois & Ellenberg, 1974) according to the following formula:
n.,
index of Jaccard (%) = + J _ x 100%
j k jk
where n. = the number of species occurring- in sample j , n, = the number of species occurring in sample k , n., = the number of species occurring in both sam
ples j and k.
b . the quantitative resemblance, based on abundance of species at the sampling s i t e s , was computed by the similarity index of Ellen-b e r g (Mueller-DomEllen-bois & EllenEllen-berg, 1974) according to the follo wing formula:
S., : 2
index of Ellenberg (%) = g + £ + s —^ x 100% j k jk
where S. = the sum of the percentage individuals of the
J species occurring only in sample j ,
S, = the sum of the percentage individuals of the species occourring only in sample . k, S., = the sum of the percentage individuals of the
species occurring in both samples j and k. 2.2. Biomass:
The total number of algae per ml (I/ML) was calculated from the number of counted algae and the volume of the original and concen trated plankton sample and the number and volume of the counted viewing fields under the microscope by the following formula:
Nx . Vt . 103 I/ML =
N2 . V2 . V3
where Nx = the number of counted algae,
Vj = the volume after concentration ( i n ml),
V2 = the volume of the sample before concentration
(in ml),
N2 = the number of counted viewing fields,
V3 = the volume of the counted viewing fields (in mm3).
2.3. Diversity:
The species diversity at the sampling sites was measured in three ways (Klapwijk, 1980; Klapwijk et a l . , 1983):
-29-by counting the number of species ( S ) in the samples (mostly a p p r b x . 100 individuals or colonies c o u n t e d ) ,
by computing species diversity indices with Margalef's formula (Odum, 1971):
S - 1 D
In N where D = index of Margalef,
S = the number of s p e c i e s ,
N = the number of organisms or cells counted to find S species.
c . by computing indices of species diversity and equitability with the Shannon-Wiener function ( K r e b s , 1972):
H = - I (p ) ( l o g2p ) i=l H = 2 io g s max ° E = H/H max
where • H = index of species d i v e r s i t y , S = number of species,
p . = proportion of total sample belonging to ith species,
E = equitability o r e v e n n e s s ( r a n g e : 0-1), H = maximum species d i v e r s i t y
max ^ J
2 . 4 . Saprobity:
The saprobity of the plankton communities was measured in three different ways (Klapwijk, 1978, 1980; Klapwijk et a l . , 1983).
a. by calculating the saprobic quotient of D r e s s c h e r and van der Mark (1976, 1980) using the following formula:
SQ C + 3D - B - 3A
A + B + C + D
where SQ = saprobic quotient ( r a n g e - 3 to + 3 ) ,
A = the number of Ciliata, indicating very severe pollution ( p o l y s a p r o b i t y ) ,
B = the number of Euglenophyceae, indicating considerable pollution ( a - m e s o s a p r o b i t y ) , C = the number of Chlorococcales and Diatomeae,
indicating moderate pollution (p-mesosapro-b i t y ) ,
D = the number of species of the Peridineae, Chrysophyceae a n d Conjugatae, indicating very slight pollution (oligosaprobity).
3 0
-b . -by calculating the sapro-bic index of Pan tie and Buck (1955) using Sladecek's (1973) and Mauch's (1976) extended lists of sa-probity indicating organisms according to the following formula:
I (n . s . ) I n.
l
where SI = saprobic index of Pan tie and Buck,
n . = abundancy e . g . number of individuals of ith species,
s. = saprobic value of individual species i.
c. by calculating the saprobic valencies according to Zelinka and Marvan (1961) using also Sladecek's (1973) and Mauch's (1976) extended lists of saprobity indicating organisms according to the following formula: 1 n. g x X = i = 1 n 2 n. g i=l l saprobity level,
abundancy e . g . number of individuals of ith species,
indicative weight of species (range 1-5), the share from the whole saprobic valency given to the Xth degree or the number of points in the respective d e g r e e .
Besides these ecological c h a r a c t e r i s t i c s , the following statistical tech niques were u s e d to evaluate and test the r e s u l t s of the water che mistry and plankton analyses:
Average linkage cluster analyses ( E v e r i t t , 1974) were used to cluster the similarity indices of Jaccard and Ellenberg.
Linear correlation and regression analyses were used according to Sokal and Rohlf (1969) to compute the relationships between different chemical and ecological parameters.
3. RESULTS
The physical and chemical measurements as well as the species composition of the planktonic communities cannot be p r e s e n t e d here in detail. The complete data are given by Klapwijk (1982). Some data are summarized in Table 3, showing that both the means as well as the minima and maxima of the various parameters differ in the diffe rent water t y p e s . Especially the canals showed r a t h e r low oxygen concentrations and relatively high n u t r i e n t concentrations in compari son with the o t h e r water t y p e s . The peat lakes showed the highest, and the deep sand pits the lowest chlorophyll-a concentrations and algal biomass (I/ML).
where X
n.
g
T a b l e 3 . Summarized d a t a on t h e w a t e r a n a l y s e s in t h e sampled w a t e r t y p e . E x p l a n a t i o n of a b b r e v i a t i o n s : COD BOD I/ML S H SQ SI SI* : chemical o x y g e n d e m a n d ; : biological o x y g e n d e m a n d ; : n u m b e r of i n d i v i d u a l s p e r ml; = d i v e r s i t y i n d e x of Margalef; = d i v e r s i t y i n d e x of S h a n n o n & W i e n e r ; : s a p r o b i c q u o t i e n t of D r e s s c h e r & v a n - s a p r o b i c i n d e x of P a n t i e & B u c k ; : s a p r o b i c i n d e x of P a n t l e & B u c k with : n u m b e r of s a m p l i n g s t a t i o n s ; : n o t m e a s u r e d . d e r M a r k ; c h a n g e d s a p r o b i c v a l e n c i e s for d o m i n a t i n g b l u e g r e e n s ; PH T e m p e r a t u r e O x y g e n C O ( m g l "1 O x y g e n s a t u r a t i o n (%) COD BOD Kjeldahl-N NH«-N N 02t N 03- N O r t h o - P T o t a l P C h l o r i d e T r a n s p a r e n c y C o n d u c t i v i t y 25 C h l o r o p h y l l - a I/ML S D H SQ SI S I * ( m g 1" ( m g f ( m g 1~ ( m g 1" ( m g f ( m g l" (mg f (mg 1-1 (m) C ( m S cm ( m g m" m i n . 6 . 9 0 0 . 0 ) 0 . 0 0 ) 13 ) 1 ) 0 . 6 ) 0 . 1 ) 0 . 0 2 ) 0 . 0 3 ) 0.08 ) 63 0 . 1 " ' ) 0 . 6 5 3) 1 156 7 1.3 0.7 - 1 . 9 1.6 1.6 C a n a l s mean ( n = 25) 7.69 10.8 7 . 1 63 53 7 4 . 2 2 . 1 3 . 3 0.77 1.02 286 0 . 9 1.63 44 ( n = 9 ) 9400 22 4 . 5 3 . 2 - 0 . 1 2 . 3 2 . 4 m a x . 9 . 0 5 2 2 . 0 26.6 221 151 75 2 5 . 0 21.0 2 2 . 4 7.4 8.2 3500 7.7 1 2 . 1 516 83800 39 7.9 4 . 7 1.2 3 . 0 3 . 0 m i n . 7 . 1 5 0 . 5 1.4 13 7 1 0 . 5 0 . 1 0 . 0 1 0 . 0 1 0 . 0 4 73 0 . 1 0 . 6 6 1 91 4 0 . 6 0 . 6 - 1 . 5 1.5 1.7 L a k e s mean ( n = 29) 8.11 11.0 10.0 88 45 5 2 . 5 0 . 6 3.14 0 . 5 0 0 . 6 8 198 0 . 8 1.36 54 ( n = 11) 29200 20 3 . 9 3 . 0 0 . 1 2 . 1 2 . 4 m a x . 9.20 2 4 . 5 2 2 . 1 218 114 33 10.0 7 . 4 17.8 5 . 9 6 . 5 450 3.2 2 . 6 8 506 142000 40 6 . 4 4 . 3 1.4 2.7 3 . 5 P e a t l a k e s m i n . 7.40 0 . 5 1.3 12 19 1 1.2 0 . 1 0 . 0 1 0 . 0 1 0 . 0 4 129 0 . 1 0 . 7 3 14 870 3 0 . 4 0 . 3 - 3 . 0 1.4 1.4 mean ( n = 13) 8.27 1 1 . 0 10.4 92 64 9 2 . 9 0 . 3 0 . 6 2 0 . 2 1 0 . 3 9 195 0 . 4 1.15 93 ( n = 9 ) 54800 16 3 . 0 2 . 3 - 0 . 6 2 . 0 2 . 9 m a x . 9.35 2 2 . 0 20.7 180 119 28 7 . 0 4 . 9 14.4 1.6 1.7 675 1.2 3 . 1 4 375 292000 29 5 . 9 3 . 8 0 . 7 3 . 5 3 . 5 D e e p s a n d p i t s m i n . 7.10 0 . 0 1.4 13 7 1 0 . 5 0 . 1 0 . 0 1 0.01 0 . 0 1 59 0 . 1 0 . 5 8 1 115 7 1.3 0 . 8 - 1 . 2 1.1 1.1 mean ( n = 5) 8.03 10.6 10.1 90 32 3 2 . 2 0 . 8 2.64 O . U 0 . 2 0 129 1.6 0 . 9 2 8 ( n = 2) 4400 17 3 . 3 2 . 6 0 . 5 1.8 1.8 m a x . 8.90 2 1 . 5 15.7 140 71 15 8 . 3 6.2 14.4 0 . 5 1.6 224 6 . 0 1.81 55 21000 36 7 . 1 4 . 4 2 . 3 2 . 5 2 . 5 m i n . 7.50 0 . 0 3 . 2 28 11 1 0 . 8 0 . 1 0.01 0.01 0 . 0 6 57 0 . 6 0 . 5 0 1 594 8 1.1 0 . 3 - 0 . 9 1.4 1.4 D e e p pools mean ( n = 2) 8.04 10.6 9 . 5 84 37 3 1.6 0 . 2 0 . 4 3 0.48 0 . 5 8 84 1.2 0 . 7 7 27 ( n = 2) 12500 19 3 . 8 2 . 8 0 . 3 2 . 1 2 . 2 m a x . 8.60 19.0 1 5 . 5 120 79 13 3 . 3 1.1 1.47 1.7 1.9 125 1.8 1.16 258 67800 35 7.2 4 . 6 1.1 2 . 6 2 . 9 D u n e lakes m i n . 7.30 0 . 0 2 . 6 23 20 1 0 . 6 0 . 1 0 . 0 1 0.01 0.02 42 0 . 2 0 . 4 6 3 -_ mean ( n = 2) 7.93 10.7 8 . 4 73 58 4 2 . 0 0 . 2 0.09 0 . 1 7 0 . 3 1 98 0 . 3 1 0 . 7 6 22 -_ m a x . 9 . 1 0 2 1 . 0 13.6 101 138 40 4 . 8 0 . 7 0 . 4 3 0 . 7 1 1.50 145 0 . 4 1.84 103 -_ I CO
3 2
-The highest diversity values ( S , D and H) were observed in the canals, the lowest in the peat lakes. D r e s s c h e r and van der Mark's (1976) saprobic quotient (SQ) was highest in the deep sand pits and lowest in the canals and the peat lakes. In c o n t r a s t , because of the opposite scale of Pantle and Buck's (1955) saprobic index, the highest SI values were observed in the canals, lakes and peat lakes and the lowest in the deep sand p i t s , probably due to their isolated situation.
The plankton species with the highest presence and abundance at t h e sampled sites are listed in Table 4. The bluegreen alga Lyng-bya limnetica, the diatoms Stephanodiscus hantzschii, Stephanodiscus as-traea v a r , minutula and Nitzschia acicularis and different chlorococ-cal green algae,of the genera Scenedesmus, Monoraphidium, Kirchne-riella, Dictyosphaerium and Tetrastrum are p r e s e n t in more than 87% of all the sampling s i t e s . The highest mean abundance was reached by t h e b l u e - g r e e n s Lyngbya limnetica (more than 7700 filaments p e r ml), Oscillatorja redekei, Oscillatoria agardhii, the diatoms Stephano discus hantzschii, Stephanodiscus astraea v a r , minutula, Diatoma elon-gatum, Nitzschia acicularis and chlorococcal green algae of different genera (all more than 200 individuals per ml). The plankton in the sampled waters can therefore be characterized generally as a green algae (Chlorococcales) and diatom community (especially Centrales of the genus Stephanodiscus). In some lakes the plankton community is dominated by a permanent bloom of filamentous b l u e - g r e e n s like Lyng bya limnetica, Oscillatoria agardhii, Oscillatoria redekei or a periodic bloom of the blue-green Microcystis aeruginosa.
Table 4. Algal species with the highest presence (in percentage p r e sent at all sample sites) and the highest abundance (in mean numbers of individuals per ml) at the sampled sites.
Species Presence Species Mean abundance
(%) (individuals . ml 1)
Stephanodiscus hantzschii GRUN. 100 Lyngbya limnetica LEMM. 7700 Dictyosphaerium pulchellum WOOD 100 Stephanodiscus hantzschii GRUN. 2900 Monoraphidium contortum (THUR.) KOM.-LEGN. 100 Oscillatoria redekei van GOOR 2400 Scenedesmus costato-granuiatus SKUJA 96 Planctonema lauterbornii SCHMIDLE 2000 T e t r a s t r u m staurogeniaeforme (SCHRÖD.) LEMM. 95 Oscillatoria agardhii GOM. 1600 Lyngbya limnetica LEMM. 95 Monoraphidium contortum (THUR.) KOM.-LEGN. 1000
Stephanodiscus astraea v. minutula ( K G . ) GRUN. 95 Dictyosphaerium pulchellum WOOD 600 Monoraphidium komarkovae NYG. 95 Scenedesmus quadricauda (TÜRP.) BREB. 400 Scenedesmus spec. 17 95 Monoraphidium komarkovae NYG. 400 Nit2schia acicularis W. SMITH 87 Planctomyces bekefü GIMESI 400 Kirchneriella.obesa (W. WEST) SCHMIDLE 87 Chlorophyt spec. 3 400 Scenedesmus quadricauda (TÜRP.) BREB. 87 Cryptomonas caudata SCHILLER 300
Scenedesmus tenuispina CHOD. 87 Scenedesmus falcatus CHOD. 300 Monoraphidium minutum (NAG.) KOM.-LEGN. 87 Scenedesmus armatus CHOD. 300 Scenedesmus falcatus CHOD. 87 Skeletonema potamos (WEBER) HASLE 300
Synura uvella E . / p e t e r s e n i i KORSCHIK 300 Diatoma elongatum (LYNGB.) AG. 200 Nitzschia acicularis W. SMITH 200 KirchnerieUa obesa (W. WEST) SCHMIDLE 200
Tetrastrum staurogeniaeforme (SCHRÖD.) LEMM. 200 Stephanodiscus astraea v . minutula ( K G . ) GRUN. 200 Scenedesmus costato-granulatus SKUJA 200 Scenedesmus indeterminanda 200
The mean species composition of the sampled sites was compared by computing similarity coefficients of Jaccard and Ellenberg (Mueller-Dombois & Ellenberg, 1974), while a grouping of the sampled stations was made by applying average linkage cluster analysis ( E v e r i t t , 1974) on the calculated similarity coefficients (Fig. 1 and 2).
-33-.262 X .297 L U □ z .332 1/1 CD CC < .36' l_> < 1 3 ,137 ra rr o i J i _ j < >-i— ca < . u * .507 ,512 co
n
1. Average linkage dendrogram of the similarity coefficients accor ding to Jaccard between the algal composition on the sampling s i t e s . Explanation of the sampling site number: canals ( 1 - 7 ) , lakes ( 8 - 1 3 ) , peat lakes (14-19), deep pools (20-21), deep sandpits (22-23). .373 CD' Z CC L U CO .583 U J ,653 O I— o cr o < >- -J62 (X < t .'32
r
1
!
i i 1n
2. Average linkage dendrogram of the similarity coefficients accor ding to Ellenberg between the algal composition on the sampling s i t e s . For explanation of sampling site numbers see Fig. 1.
-34-Figure 1 shows the cluster dendrogram of the Jaccard indices. Dis tinct c l u s t e r s can be distinguished: From left to right a group of four canals can be seen (no. 1, 7, 3 , 6 ) , then a small group of t h r e e canals ( n o . 2, 4, 5 ) , a group of t h r e e lakes ( n o . 8-10) followed by a deep lake (no. 22). Next to that a cluster of three shallow peat lakes ( n o . 12, 13 and 19) and one deep pool (no. 20) and two shallow peat lakes ( n o . 14 and 16) can be o b s e r v e d . Then a large lake (no 11), two shallow peat lakes ( n o . 15 and 17) and finally to the right two isolated deep waters (no. 21 and 23) and an isolated polder lake ( n o . 18).
Similar r e s u l t s showed the clusteranalysis of Ellenberg's indices, which also takes the numbers of the different species into account (Fig. 2 ) . The clusters seem to be mainly determined by the. dominant species on the sampling s i t e s . From left to r i g h t in Figure 2 a group of canals mainly dominated by Chlorococcales and Centrales ( n o . 1, 2, 5) and lakes ( n o . 8, 10) can be seen, then a large group of mainly lakes dominated by filamentous bluegreen algae (no. 7, 16, 15, 12, 14, 19, 13, 20, 17), followed by two more polluted canals ( n o . 3 and 4 ) . Next to t h a t a small cluster of a canal ( n o . 6) and a polderlake
(no. 18) and two lakes dominated in the late summer by Microcystis aeruginosa ( n o . 9, 11). Finally to the right a cluster of two deep waters ( n o . 21, 22) and totally separated an isolated and unpolluted deep sand pit (no. 23), which seems to display a quite different plankton composition.
Figures 1 and 2 show also that the qualitative resemblance in species composition is not very high (approximately 50%), b u t that the quantitative resemblance is generally much, higher ( a p p r o x . 80%) between the sampling sites. In both a s p e c t s , the species composition seems to be correlated to a large extent with the geomorphology of the sampling s i t e s . However, it is not clear whether this is caused by the geomorphology of the sampling site or by its chemical c h a r a c t e r i s tics, since it has been shown that the latter is depending on the wa ter type (Table 3 ) . Apart from that it is obvious that the degree of pollution and eutrophication is also determining the species composi tion.
3 . 1 . Suitable parameters for the Caspers and Karbe scheme
The aim of this study was to find suitable parameters, which can be used to fill in the scheme of Caspers and Karbe in an ecologically based and consistent way. Since the system has to be applied in the practical water management, simple physical and chemical parameters, which are normally determined in a routine monitoring programme, are considered in this r e s p e c t . By comparing these parameters with more sophisticated ecological characteristics derived from plankton countings, such as biomass, diversity and saprobity. indices, an attempt has been made to find cheap and simple determinable p a r a m e t e r s , suitable for use in the Caspers and Karbe scheme for the aspects of bioactivity (production and respiration) and oxygen regime.
Therefore, with the aid of product-moment correlation analyses between the measured physical and chemical parameters and the ecolo gical plankton c h a r a c t e r i s t i c s , it became evident if and in what way the parameters were correlated with each other and with specific pa rameters indicating organic pollution, e . g . BOD, 02, COD, or e u t r o phication, e . g . N 03- N , total P, chlorophyll-a (Table 5 ) . In this table can be seen that the correlation between several parameters is some times highly significant.
Table 5. Matrix of product-moment correlations between several physical and chemical parameters and plankton c h a r a c t e r i s t i c s . Ecologically significant correlations, mentioned in the t e x t , are u n d e r l i n e d .
Explanation of a b b r e v i a t i o n s : CHL-a = chlorophyll-a; 02 = oxygen c o n t e n t ; 02% = oxygen s a t u r a t i o n ; E = equitability index of Shannon-Wiener; for other abbreviations see Table 3 .
parameters: Temp. pH Kj-N NH4-N N02+N03-N o-P t-P CHL-a BOD COD • 02 02% I/ML T r a n s - S D H E SQ SI SI* parency *** * *** *** '*** *** *** * ** ** Temperature -1.00 0.20 -0.08 -0.16 -0.21 0.02 0.04 0.12 0.12 0.03 -0.34 0.03 0.16 -0.05 0.19 0.19 0.10 0.04 0^02 -0.12 0.00 ** *** * * * * * * * * * * * * * * *** *** *** *** ** ****** *** *** ** *** *** pH 1.00 -0.11 -0.36 -0.31 -0.15 -0.11 0.42 0.25 0.29 0.57 0.68 0.46 -0.09 -0.35 -0.37 -0.34 -0.25 -0.23 -0.21 0J!2 *** *** *** *** *** *** *** *** *** *** *** *** Kjeldahl-N - 1.00 0.85 0.02 0.68 0.73 0.32 0.68 0.55 -0.26 -0.29 -0.01 -0.31 0.10 0.08 0.04 0.02 -0.33 0.43 0J!S *** *** *** *** *** *** *** ** *** ** * * * *** NH,-N - 1.00 . 0 . 1 2 0.67 0.66 -0.05 0.37 0.16 -0.38 -0.45 -0.18 -0.11 0.17 0.16 0.13 0.10 -0.17 0.38 0.05 *** *** *** ****** * * * * * * * * * * N 02* N 03- N 1.00 0.02 0.01 -0.25 -0.19 -0.20 0.02 -0.06 -0.30 0.15 0.14 0.15 0.19 0.17 0.08 0.32 -0.15 *** * *** *** *** *** * *** *** *** * *** Ortho-P — • — 1.00 0.97 0.07 0.34 0.23 -0.33 -0.33 -0.13 -0.12 0.22 0.21 0.15 0.10 -0.07 0.29 0.03 *** *** *** *** *** *** *** *** * *** Total-P - - 1 0 0 0..1B 0.44 0.32 -0.30 -0.30 -0.08 -0.18 0.22 0.21 0.14 0.08 -0.11 0.33 0.07 *** *** *** *** *** *** *** *** *** *** *** ** *** Chlorophyll-a - 1 0 0 (L68 0.54 0.23 0.28 0_j>6 -0.37 -0.21 - 0 . 2 5 -0.31 -0.30 -0.48 0.19 0.52 *** *** *** * * *** *** *** BOD - 1 0 0 0.66 -0.02 0.03 0.34 -0.43 -0.06 - 0 . 0 8 . -0.14 - 0 . 1 5 -0.53 0.37 OJ53 * ** *** *** * * ** **. *** *** *** , COD - 1 0 0 0.07 0.10 0.34 -0.45 -0.13 -0.15 -0.19 -0.17 -0.54 0.27 0.48 t o en *** *** *** *** *** *** ** | 02 - - 1.00 0.92 0.22 0.05 -0.42 -0.44 -0.37 . -0.28 -0.10 -0.18 0.06 *** *** *** *** *** *** 02- s a t u r a t i o n - — 1.00 0.31 -0.03 -0.40 -0.41 -0.37 -0.27 -0.10 -0.24 0.08 *** ** *** *** *** *** *** I/ML 1.00 -0.29 -0.18 -0.22 -0.33 -0.36 -0.24 0.04 0.48 * *** *** *** T r a n s p a r e n c y - - 1 0 0 - 0 . 1 3 -0.12 -0.11 - 0 . 0 8 0.51 -0.46 -0.56 *** *** *** *** *** S - 1.00 0.99 0.82 0.57 0.37 0.09 -0.22 *** *** *** *** D 1.00 0.86 0.63 0.37 0.08 -0.24 *** *** *** H - - - - 1.00 0.93 0.28 0.03 - 0 . 2 5 *** E - - 1.00 0.12 -0.01 -0.19 SQ - -■ 1 00 -CL34 -0.65 *** SI > - 1.00 0.45 SI* — — - - — 1.00 No. of observation pairs 1085 1085 1085 1085 1085 1085 1085 1085 1085 1085 1085 1085 258 1085 258 258 258 258 189 260 258
-36-In this respect it is i n t e r e s t i n g to s t r e s s the moderate correla tion between CHLa and BOD ( r = 0 . 6 8 ) , indicating that the d e g r a -dable organic matter in the sampled waters consists for the most p a r t of algae instead of unpurified wastewater. Therefore, in most waters the signs of saprobity are less clear than the signs of eutrophication. Furthermore it is conspicuous t h a t the negative correlation between CHL-a and NH4-N ( r = -0.05) or N02+N03-N ( r = -0.25) in compari son with the positive correlation between CHL-a and ortho-P indicates that the algae in most of the waters are more likely to be limited by nitrogen than by phosphorus (cf. van der Does & Klapwijk, 1987; de Vries & Klapwijk, 1987). Note f u r t h e r that the correlation between the saprobic quotient SQ and the Si-index of Pantle and Buck, using Sladecek's (1973) indicator values, is low ( r = - 0 . 3 4 ; n = 189) ( N . B . : The sign is negative due to the opposite scales of the two indices).
On the basis of these correlation analyses the following parame t e r s were chosen to use in the scheme of Caspers and Karbe for the different a s p e c t s : CHL-a (for p r o d u c t i o n ) , BOD (for r e s p i r a t i o n ) , 02 or 02% (for the oxygen regime), I/ML (for biomass), D (for diver sity) and SI or SQ (for s a p r o b i t y ) .
3.2. Proposal for filling in Caspers and Karbe's scheme
The above mentioned parameters (CHL-a, BOD, 02%, I/ML, D
and SI or SQ) were critically reviewed and mutually compared in or der to achieve a consistent filling in of Caspers and Karbe's scheme. 3 . 2 . 1 . Production
According to Caspers and Karbe (1967) the intensity of p r i mary production is increasing from class I to class IV, while it is very moderate in class V and absent in class VI (Table 1). Since class I, r e p r e s e n t i n g extremely clean waters like mountain s p r i n g s , is probably lacking in South Holland, the CHL-a measurements, simula ting primary production, should fit in class II to IV with the highest concentrations ( e . g . >100 mg m 3) in class IV and the lowest ( e . g . <25 mg m 3) in class II. Due to the high correlation between CHL-a and BOD it was necessary to tune both parameters precisely to each o t h e r , because otherwise discrepancies could arise in the scheme. In our data the maximal CHL-a/BOD ratio was approximately 20 : 1, BOD e x p r e s s e d as mg 1 1 and chlorophyll-a as mg m 3 (Fig. 3 ) . Due to the fact that the highest algal production is found in the summer months, the average summer concentration of CHL-a is chosen as most suitable for use in the scheme.
3 . 2 . 2 . Respiration
According to Caspers and Karbe (1967) decomposition is in creasing from class I to class VI (Table 1 ) . Since class I is unlikely in South-Holland and class VI is meant for untreated wastewaters with BOD values from 100-600 mg 02 l "1, the measured BOD values should fit into the classes II to V. Sladecek (1973) already mentioned BOD s t a n d a r d s for stagnant waters (Table 6 ) . Since BOD values in South-Holland mostly appeared to fall into the classes III and IV, a subdivi sion of these classes is considered. Due to the occurring fluctuations in the BOD, also by the different seasons, class limits based on p e r -centile values will be preferable to year averages or maxima, although the correlation between the 75 percentile and the year average of the BOD values was very high ( r = 0.98; n = 13).
-37-E er a I _ i _ i >-T n o a: o _ i X o 500 400 300 200 100 0 -1 ■ l a 2B 3 B 6B 7 8 16* 43 ■ BSB 75 ■ 422» 6 8 * i 3 a 12» 28B 53 B 39 B 4 0 a BOD 2 a 2 1 3 a 2 a 1 4 a 2 0B 33a 16 a 13 a IS a 1 1 a 1 a 1 a l a 2 a 2 1 4 a 3 a 1 0 a 9 a 10 a 10 a 1 a 4 a 1 versus CHL0R0PHYLL-a i i 2 B 2 a SB 6 B 3 B 3 B 3 B 1 B I B 2 B I B 2 B I B 6B 4 B I B I B I B 3 B 1 1 B 1 B 1 B 3 B 1 B 1 B 1 a l a l a 1 I B 1 B 1 a I B I B 1 a l a 1 1 1 1 ■ 1 10 20 30 40 50 BOD ( m g / l )
16 a - NUMBER OF PAIRED OBSERVATIONS
Fig. 3. Relation between Biological Oxygen Demand (BOD) and Chlo-rophyll-a (CHL-a) v a l u e s .
Table 6. Saprobity levels and corresponding BOD and oxygen values for s t a n d i n g water bodies according to Sladecek (1973).
level 0 I 11 III IV V VI katharobity xenosaprobity oligosaprobity 0-mesosaprobity a-mesosaprobity polysaprobity isosaprobity ] <m < < < < < < BOD . g f1) 0 2 5 10 15 100 600
