European Large Lakes – Ecosystem changes and their ecological and socioeconomic impacts doc

European Large Lakes –
Ecosystem changes and their ecological and socioeconomic
impacts
Developments in Hydrobiology 199
Series editor
K. Martens
European Large Lakes
Ecosystem changes and their ecological and
socioeconomic impacts
Edited by
Tiina No
˜
ges
1
, Reiner Eckmann
2
,Ku
¨
lli Kangur
1
,
Peeter No
˜
ges
1,3
, Anu Reinart
4
, Gulnara Roll
5
,

Heikki Simola
6
& Markku Viljanen
6
1
Centre for Limnology, Institute of Agricultural and Environmental Sciences, Estonian University of Life Sciences, 61101 Rannu,
Tartumaa, Estonia
2
University of Konstanz, Limnological Institute, D-78457 Konstanz, Germany
3
European Commission – Joint Research Centre, Institute for Environment and Sustainability Via Enrico Fermi 1,
21020 Ispra (VA), Italy
4
Tartu Observatory, T~oravere, 61602 Tartu County, Estonia
5
Peipsi Centre for Transboundary Cooperation, Aleksandri 9, Tartu, Estonia
6
University of Joensuu, Faculty of Biosciences, Ecological Research Institute, P.O. Box 111, FI-80101 Joensuu, Finland
Reprinted from Hydrobiologia, Volume 599 (2008)
123
Library of Congress Cataloging-in-Publication Data
A C.I.P. Catalogue record for this book is available from the Library of Congress.
ISBN-13: 978-1-4020-8378-5
Published by Springer,
P.O. Box 17, 3300 AA Dordrecht, The Netherlands
Cite this publication as Hydrobiologia vol. 599 (2008).
Cover illustration: Lake Vo
˜
rtsja
¨

rv, Estonia. Photo: Priit Zingel.
Printed on acid-free paper
All Rights reserved
Ó 2008 Springer
No part of this material protected by this copyright notice may be reproduced or utilized in any form
or by any means, electronic or mechanical, including photocopying, recording or by any information
storage and retrieval system, without written permission from the copyright owner.
Printed in the Netherlands
TABLE OF CONTENTS
Preface 1–2
CLIMATE CHANGE AND ANTHROPOGENIC IMPACTS ON LARGE LAKES ECOSYSTEMS
Nutrients and phytoplankton in Lake Peipsi during two periods that differed in water
level and temperature
M. Haldna, A. Milius, R. Laugaste, K. Kangur 3–11
Pollen, diatom and plant macrofossil assemblages indicate a low water level phase of
Lake Peipsi at the beginning of the Holocene
T. Hang, V. Kalm, K. Kihno, M. Milkevic
ˇ
ius 13–21
Water level changes in a large shallow lake as reflected by the plankton:periphyton-
ratio of sedimentary diatoms
A. Heinsalu, H. Luup, T. Alliksaar, P. No
˜
ges, T. No
˜
ges 23–30
Changes in spatial distribution of phosphorus and nitrogen in the large north-
temperate lowland Lake Peipsi (Estonia/Russia)
K. Kangur, T. Mo
¨

ls 31–39
Recent trends in Lake Ladoga ice cover
S.G. Karetnikov, M.A. Naumenko 41–48
History of anthropogenically mediated eutrophication of Lake Peipsi as revealed by
the stratigraphy of fossil pigments and molecular size fractions of pore-water
dissolved organic matter
A. Leeben, I. To
˜
nno, R. Freiberg, V. Lepane, N. Bonningues, N. Makaro
˜
ts
ˇ
eva,
A. Heinsalu, T. Alliksaar 49–58
Seasonality and trends in the Secchi disk transparency of Lake Ladoga
M.A. Naumenko 59–65
Silicon load and the development of diatoms in three river-lake systems in count ries
surrounding the Baltic Sea
P. No
˜
ges, T. No
˜
ges, R. Adrian, G.A. Weyhenmeyer 67–76
Critical N:P ratio for cyanobacteria and N2-fixing species in the large shall ow
temperate lakes Peipsi and Vo
˜
rtsja
¨
rv, North-East Europe
T. No

˜
ges, R. Laugaste, P. No
˜
ges, I. To
˜
nno 77–86
Phytoplankton nitrogen demand and the significance of internal and external nitrogen
sources in a large shallow lake (Lake Balaton, Hungary)
M. Pre
´
sing, T. Preston, A. Taka
´
tsy, P. Spr
}
ober, A.W. Kova
´
cs, L. Vo
¨
ro
¨
s, G. Kenesi,
I. Ko
´
bor 87–95
Changes in the water level of Lake Peipsi and their reflection in a sediment core
J M. Punning, G. Kapanen, T. Hang, N. Davydova, M. Kangur 97–104
Rates of change in physical and chemical lake variables – ar e they comparable
between large and small lakes?
G.A. Weyhenmeyer 105–110
Increasingly ice-free winters and their effects on water quality in SwedenÕs largest

lakes
G.A. Weyhenmeyer, A K. Westo
¨
o
¨
, E. Wille
´
n 111–118
Phosphorus fractions and alkaline phosphatase activity in sediments of a large
eutrophic Chinese lake (Lake Taihu)
Y. Zhou, C. Song, X. Cao, J. Li, G. Chen, Z. Xia, P. Jiang 119–125
FOOD WEB INTERACTIONS AND DYNAMICS IN LARGE LAKES
The impact of the invasive Ponto-Caspian amphipod Pontogammarus robustoides on
littoral communities in Lithuanian lakes
S. Gumuliauskait
_
e, K. Arbac
ˇ
iauskas 127–134
Spatiotemporal and long-term variation in phytoplankton communities in the
oligotrophic Lake Pyha
¨
ja
¨
rvi on the Finnish-Russian border
A L. Holopainen, L. Lepisto
¨
, R. Niinioja, A. Ra
¨
mo

¨
135–141
Plant-associated invertebrates and hydrological balance in the large volcanic Lake
Bracciano (Central Italy) during two years with different water levels
L. Mastrantuono, A.G. Solimini, P. No
˜
ges, M. Bazzanti 143–152
A comparison of zooplankton densities and biomass in Lakes Peipsi and Vo
˜
rtsja
¨
rv
(Estonia): rotifers and crustaceans versus ciliates
P. Zingel, J. Haberman 153–159
MODELING TOOLS IN LARGE LAKES RESEARCH
Validation of the MERIS products on large European lakes: Peipsi, Va
¨
nern and Va
¨
ttern
K. Alikas, A. Reinart 161–168
Relations of phytoplankton in situ primary production, chlorophyll concentration and
underwater irradiance in turbid lakes
H. Arst, T. No
˜
ges, P. No
˜
ges, B. Paavel 169–176
Models as tools for understanding past, recent and future changes in large lakes
T. Blenckner 177–182

The ice cover on small and large lakes: scaling analysis and mathematical modelling
M. Leppa
¨
ranta, K. Wang 183–189
Effects of warmer world scenarios on hydrologic inputs to Lake Ma
¨
laren, Swe den and
implications for nutrient loads
K. Moore, D. Pierson, K. Pettersson, E. Schneiderman, P. Samuelsson 191–199
Variability of bio-optical parameters in two North-European large lakes
B. Paavel, H. Arst, A. Reinart 201–211
Contributions of DOC from surface and groundflow into Lake Vo
˜
rtsja
¨
rv (Estonia)
T. Tamm, T. No
˜
ges, A. Ja
¨
rvet, F. Bouraoui 213–220
vi
WATER POLICY AND SOCIOECONOMIC ASPECTS OF LARGE LAKE MANAGEMENT
Implications of flexibility in European Community environmental law: exemptions
from environmental objectives in the Water Framework Directive
E. Gro
¨
nlund, T. Ma
¨
a

¨
tta
¨
221–226
Analysis of long-term ecological status of Lake Balaton based on the ALMOBAL
phytoplankton database
E
´
. Hajnal, J. Padisa
´
k 227–237
Towards ecological goals for the heavily modified lakes in the IJsselmeer area, The
Netherlands
E. Lammens, F. van Luijn, Y. Wessels, H. Bouwhuis, R. Noordhuis, R. Portielje,
D. van der Molen 239–247
Environmental awareness of the permanent inhabitants of towns and villages on the
shores of Lake Balaton with special reference to issues related to global climate
change
A. Va
´
rkuti, K. Kova
´
cs, C. Stenger-Kova
´
cs, J. Padisa
´
k 249–257
Highlights of large lake research and management in Europe
P. No
˜

ges, K. Kangur, T. No
˜
ges, A. Reinart, H. Simola, M. Viljanen 259–276
vii
ELL
S 200
7
Pr
eface
Ó
S
pr
i
nger Sc
i
ence+Bus
i
ness Me
di
a B.V. 200
8
Large
l
a
k
es are
i
mportant
b
ecause o

f
t
h
e
i
rs
i
ze an
d
e
cological distinctiveness, as well as the ir economic a n
d
c
ultural value. Optimal mana
g
ement of them requires a
proper un
d
erstan
di
ng o
f
ant
h
ropogen
i
c
i
mpacts,
b

ot
h
o
n
the lake ecosystems, as such and on the services they
provide for society. The specific structural and func
-
t
i
ona
l
propert
i
es o
fl
ar
g
e
l
a
k
es, e.
g
.morp
h
o
l
o
gy
,

h
y
d
rograp
h
y,
bi
ogeoc
h
em
i
ca
l
cyc
l
es, an
df
oo
d
-we
b
structure, are all directly related to t heir size. T hese
v
u
l
nera
bl
eecos
y
stems o

f
ten su
ff
er
f
rom acce
l
erate
d
e
utrop
hi
cat
i
on, over-
fi
s
hi
ng, tox
i
c contam
i
nat
i
on, an
d
i
nvasive species. Large lakes offer socio-economic
b
ene

fi
ts an
d
cou
ld b
euse
di
nman
y
wa
y
s, an
d
are o
f
ten
a
reas
i
nw
hi
c
h
econom
i
c, cu
l
tura
l
an

d
po
li
t
i
ca
li
nterests
o
ver
l
ap. T
h
ese mu
l
t
i
p
l
e uses create po tent
i
a
l
r
i
s
k
s
f
or t

he
h
ealth and functionin
g
of the ecos
y
stem. Dissemination
of i
n
f
ormat
i
on a
b
out t
h
er
i
s
k
s cause
dbyh
uman ac t
i
v
i
t
i
e
s

i
st
h
e
fi
rst step towar
d
encourag
i
ng an
d
ena
bli
ng t
h
e
c
ommunit
y
to participate in decision-makin
g
about th
e
u
se an
d
protect
i
on o
fl

ar
g
e
l
a
k
es. Severa
ll
ar
g
e
l
a
k
es
i
n
Europe (La
k
es Geneva, Constance, Pe
i
ps
i
an
d
Magg
i
-
o
re, forinstance

)
or their catchment areas
(
those of Lakes
Ladoga, Va
nern an
d
Sa
i
maa) are s
h
are
db
etween two or
m
ore countr
i
es, w
hi
c
h
ma
k
es
i
nternat
i
ona
l
cooperat

i
on a
prerequisite for their sustainable management.
T
h
e European Lar
g
eLa
k
es S
y
mpos
i
um (ELLS
)
2
006, which took
p
lace in Tartu, Estonia, 11–1
5
S
eptember, 200
6
, focused especiall
y
on the ecos
y
stems
of
European

l
arge
l
a
k
es an
d
t
h
e
i
reco
l
og
i
ca
l
an
d
soc
i
o
-
economic impacts. The ELLS grew out of the Interna-
t
ional Lake Ladoga Symposia organized in 1993, 1996
,
1999, an
d
2002, w

hi
c
hi
mprove
d
our un
d
erstan
di
n
g
o
f
th
e structure an
df
unct
i
on
i
n
g
not on
ly
o
f
La
k
eLa
d

o
g
a
,
b
ut a
l
so o
f
ot
h
er
l
arge nort
h
ern
l
a
k
e ecosystems. T
he
group of problems regarding the present status of larg
e
lakes and the directions of change are much the same i
n
all these cases: threats caused b
y
direct human impac
t
an

dby
c
li
mate c
h
an
g
e, protect
i
on nee
d
san
d
restorat
i
on
measures. It
h
as t
h
ere
f
ore
b
ecome e
vid
ent t
h
a
t

i
nternat
i
ona
l
exc
h
ange o
f
op
i
n
i
ons an
d
sc
i
ent
ifi
c
i
n
f
or
-
mation from large lake research in Europe is necessary
.
The ELLS provided a platform for (i) discussin
g
ne

w
s
c
i
ent
ifi
c
fi
n
di
n
g
sre
g
ar
di
n
g
t
h
e
f
unct
i
on
i
n
g
o
fl

ar
ge
l
a
k
eecos
y
stems un
d
er t
h
e
i
n
fl
uence o
f
ant
h
ropo
g
en
i
c
and climatic stressors, (ii) enhancing the communica
-
t
ion and exchange of ideas among scientists, wate
r
mana

g
ers and politicians, and (iii) fosterin
g
interna-
ti
ona
l
cooperat
i
on
i
na
ll
aspects o
fi
nvest
ig
at
i
on an
d
mana
g
ement o
fb
ot
h
nat
i
ona

l
an
d
transnat
i
ona
l
Euro
-
p
ean water
b
o
di
es
.
The ELLS was organized by the International
Or
g
an
i
z
i
n
g
Comm
i
ttee
i
nc

l
u
di
n
g
t
h
e
f
o
ll
ow
i
n
g
mem
-
bers: Dr. Tiina No
ges (C
h
a
i
r; Eston
i
a), Dr. Mar
kk
u
Vil
j
anen (Vice chair; Finland), M.A. Tuula Toivanen

(Secretary; Finland), M.Sc. Ain Ja
r
va
l
t(Eston
i
a)
,
a
a
Guest Editors: T. No
ges, R. Eckmann, K. Kangur, P. No
g
es
,
A
. Reinart, G. Roll, H. Simola and M. Viljane
n
European Lar
g
e Lakes—Ecos
y
stem chan
g
es and thei
r
ecological and socioeconomic impact
s
1
23

Hy
drobiolo
g
ia (2008)
5
99:1–2
D
OI 10.1007/s107
5
0-008-9304-
5
M.A. Kati Kangur (Estonia), Dr. Ku
l
li Kan
g
ur
(
Eston
i
a), Dr. Ve
lj
oK
i
san
d
(Eston
i
a), Dr. Anu Re
i
nar

t
(
Estonia
)
, Dr. Gulnara Roll
(
Estonia
)
, M.Sc. Le
a
Tuvikene (Estonia), Dr. Peeter No
g
es
(
European
C
om-
mi
ss
i
on), Pro
f
.Re
i
ner Ec
k
mann (Germany), Pro
f
.
V

alentina G. Drabkova
(
Russia
)
, Prof. Vladislav A
.
Rumyantsev (Russia) and Dr. Niklas Stro
mbeck
(
Swe
d
en). T
h
epract
i
ca
l
arrangements were ma
d
e
by
t
h
eCentre
f
or L
i
mno
l
ogy, Eston

i
an Un
i
vers
i
ty o
f
L
if
e
Sciences; University of Joensuu, Finland; and Th
e
P
e
i
ps
i
Centre
f
or Trans
b
oun
d
ar
y
Cooperat
i
on, Eston
i
a.

T
h
e Internat
i
ona
l
A
d
v
i
sory Comm
i
ttee compr
i
se
d
P
rof. Dr. Martin Dokulil (Austria), Dr. Glen George
(
UK), Pro
f
.Er
ik
Jeppesen an
d
Pro
f
. Dr. Sven Er
ik
J

ørgensen (Denmar
k
), Pro
f
. Roger Jones an
d
Pro
f
.
J
ouko Sarvala
(
Finland
)
, Prof. Ulrich Lemmin an
d
Prof. Dr. Alfred Johny Wu
e
st (Sw
i
tzer
l
an
d
), Dr.
Mohiuddin Munawar (Canada), Prof. Judit Padisa
´
k
,
(Hungary), Dr. Anne Lyc

h
eSo
lh
e
i
m (Norway), Pro
f
.
D
r. Ulrich Sommer (German
y
), Dr. Ole
g
A. Timosh
-
ki
n (Russ
i
a) an
d
Dr. Gesa We
yh
enme
y
er (Swe
d
en).
ELLS
h
a

d
170 part
i
c
i
pants
f
rom 20 countr
i
es
:
A
ustria
(
3
)
, Belarus
(
1
)
, Canada
(
1
)
, China
(
2
)
, Czec
h

R
e
p
ublic (3), Estonia (56), Finland (33), France (2),
Germany (11), Hungary (
6
), Italy (2), Latvia (3),
Lithuania
(
3
)
, Poland
(
1
)
, Russian Federation
(
28
),
Sweden (4), Switzerland (2), The Netherlands (
6
),
Un
i
te
d
K
i
n
gd

om (2), USA (1)
.
T
he themes at ELLS were as follows
:
1
. Climate chan
g
e and anthropo
g
enic impacts o
n
l
ar
g
e
l
a
k
e ecos
y
stems (
k
e
y
note spea
k
er Dr. G
l
en

D
. George)
.
2
. Food web interactions and dynamics (keynote
speaker Dr. Alois Herzi
g
).
3. Modelin
g
tools in lar
g
e lakes research (ke
y
note
spea
k
er Dr. T
h
orsten B
l
enc
k
ner)
.
4
. The Water Framework Directive and large lakes
(
ke
y

note speaker Dr. Anne L
y
che Solheim)
.
5
. Socio-economic aspects of water resource
a
nd catchment management (keynote speaker
Dr. Ragnar Lo
f
stedt
)
.
6
. Policy support systems for the sustainable man-
a
gement of large lakes affected by global
changes (keynote speaker Dr. Ramesh Gulati).
T
h
e Guest E
di
tors o
f
t
hi
s Spec
i
a
l

Issue s
i
ncere
l
y
th
an
k
a
ll
organ
i
zers an
d
presenters o
f
ELLS, a
ll
contributors to the Special Issue and all anonymous
rev
i
ewers
f
or t
h
e
i
r
i
nva

l
ua
bl
e
h
e
l
p
i
n
i
mprov
i
n
g
t
h
e
sc
i
ent
ifi
c qua
li
ty o
f
t
h
e manuscr
i

pts. Our spec
i
a
l
g
ratitude goes to our secretary Tuula Toivanen for
h
er
i
mmense tec
h
n
i
ca
l
ass
i
stance an
dh
er a
l
wa
ys
pat
i
ent an
df
r
i
en

dl
y att
i
tu
d
e, to t
h
e sta
ff
o
f
T
h
eoret
-
ical and Cell Biology Consultancy led by Paul S.
A
g
utter
f
or t
h
e
i
r
highly
pro
f
ess
i

ona
ll
an
g
ua
g
ee
di
t-
ing, and to Judit Padisa
´
k
, Gesa Wey
h
enmeyer, Jou
k
o
Sarva
l
aan
d
T
h
orsten B
l
enc
k
ner
f
or t

h
e
i
r
h
e
l
pan
d
support durin
g
the critical sta
g
es of the editin
g
process
.
The ELLS organizers and the Guest Editors ar
e
g
reatl
y
indepted to the Estonian Environmental
I
nvestment Centre
f
or prov
idi
n
gfi

nanc
i
a
l
suppor
t
f
or ELLS organizing and editing of this Special Issue.
2
Hy
drobiolo
g
ia (2008)
5
99:1–
2
1
2
3
ELL
S 200
7
Nutr
i
ents and phytoplankton
i
n Lake Pe
i
ps
i

dur
i
ng tw
o
p
eriods that differed in water level and tem
p
erature
M
a
r
i
n
a
H
a
l
d
n
a
Æ
Æ
An
u
M
i
l
ius
Æ
Æ

R
eet
L
augaste
Æ
Æ
Ku
¨
ll
i
Kangu
r
Ó
S
pringer Science+Business Media B.V. 200
7
Abs
tr
ac
t Data for the ve
g
etation periods (Ma
y
–
November) of 1985–2003 were used to collate the
n
utrient content and biomass of the most im
p
ortan
t

ph
y
toplankton
g
roups in Lake Peipsi (Estonia). Two
per
i
o
d
s
diff
er
i
n
gi
n externa
l
nutr
i
ent
l
oa
d
an
d
water
l
evel were compared by analysis of variance. The
y
ears 198

5
–1988 were characterized b
y
the hi
g
hest
l
oa
d
so
f
n
i
trogen an
d
p
h
osp
h
orus,
hi
g
h
water
l
eve
l
a
nd cool summers. The years 2000–2003 wer
e

d
istinguished by low or medium water levels an
d
warm summe rs. T
h
e
fi
rst per
i
o
d
s
h
owe
d
stat
i
st
i
ca
lly
s
i
gn
ifi
cant
l
y
hi
g

h
er va
l
ues o
f
tota
l
n
i
trogen (
N
tot
)
an
d
ahi
g
h
er N
tot
:P
tot
m
ass rat
i
o. T
h
e secon
d
per

i
o
d
showed a higher content of total phosphorus (
P
to
t
)
,
a
h
i
g
her ratio of dissolved inor
g
anic compounds N to
P
a
n
d high
er p
hy
top
l
an
k
ton an
d
c
y

ano
b
acter
i
a
lbi
o
-
masses. Comparison between parts of the lake
demonstrated that the differences between the two
p
eriods were more evident in the shallower and
strong
l
y eutrop
hi
c parts, La
k
eP
ihk
va an
d
La
k
e
La
mmija
r
v, than in the largest and deepest part, the
mo

d
erate
ly
eutrop
hi
cLa
k
ePe
i
ps
i
s
.
s
.
Temperature
a
n
d
water
l
eve
l
acte
d
synerg
i
st
i
ca

ll
yan
d
ev
id
ent
l
y
influenced phytoplankton via nutrients, promotin
g
i
nterna
ll
oa
di
n
g
w
h
en t
h
e water
l
eve
l
was
l
ow an
d
t

h
e
temperature
hi
g
h
.T
h
ee
ff
ect o
f
water
l
eve
l
was
stronger in the shallowest part, Lake Pihkva. The
diff
erence
i
nP
tot
c
ontent between the southern and
northern
p
arts was twofold; the N
tot
:P

tot
mass
r
at
i
o
w
as s
ig
n
ifi
cant
ly l
ower
i
nt
h
e sout
h
ern parts, an
d
phytoplankton biomass (particularly the biomass of
c
y
anobacteria) was si
g
nificantl
y
hi
g

her for Lake
Pihkva and Lake La
mmija
r
vt
h
an
f
or La
k
ePe
ip
s
i
s
.
s
.
K
e
y
word
s
L
arge and shallow lake
Á
Water level
Á
N
utrients

Á
Ph
y
toplankton
Á
C
yano
b
acter
i
a
I
ntr
oduc
t
ion
The water tem
p
erature and water level in a lake affect
w
ater c
h
em
i
str
y
(nutr
i
ents) an
dbi

ota (p
l
an
k
ton,
fi
s
h)
b
ot
hdi
rect
l
yan
di
n
di
rect
l
y. H
i
g
h
temperature pro-
motes resuspension of phosphorus from sediments
Guest editors: T. No
ges, R. Eckmann, K. Kangur, P. No
ges,
A.
R

e
i
nart, G. Ro
ll
,H.S
i
mo
l
a & M. V
ilj
ane
n
European Lar
g
eLa
k
es – Ecos
y
stem c
h
an
g
es an
d
t
h
e
ir
eco
l

og
i
ca
l
an
d
soc
i
oeconom
i
c
i
mpact
s
M
.
Haldna
Á
A.
Milius
Á
R
. Lau
g
ast
e
Á
K
. Kan
g

ur
(
&
)
I
nst
i
tute o
f
A
g
r
i
cu
l
tura
l
an
d
Env
i
ronmenta
l
Sc
i
ences,
E
stonian Universit
y
of Life Sciences, Kreutzwaldi 64,

5
1014 Tartu
,
Estoni
a
e-mail: k
y
lli.kan
g

M
.Ha
ld
na
e-mail: marina.haldna
@
emu.e
e
A
. Milius
e-mail: anu.milius
@
emu.e
e
R
. Lau
g
aste
e-ma
il

: reet.
l

e
1
23
Hy
drobiolo
g
ia (2008)
5
99:3–11
D
OI 10.1007/s107
5
0-007-9208-9
(
Pettersson et al., 2003), decrease in the N:P ratio an
d
c
yano
b
acter
i
a
lbl
ooms. Weat
h
er-
d

r
i
ven c
h
anges ca
n
e
xceed or
p
revent eutro
p
hication
p
rocess in the lak
e
(
Padisak & Koncsos, 2002). Na
g
id et al. (2001) an
d
No
ges et a
l
. (2003) stresse
d
t
h
e
i
ncrease

i
n
i
nterna
l
l
oading during periods of low water level. In the
l
ar
g
e, shallow, moderatel
y
eutrophic R
y
binsk Reser
-
v
o
i
r, water content
i
st
h
e most s
i
gn
ifi
cant
f
actor

i
nt
he
c
ontro
l
o
f
p
h
ytop
l
an
k
ton, an
d
t
h
e
hi
g
h
est va
l
ues o
f
c
hlorophyl
l
a

(
Chl
a
)
occur in periods of extremely
l
ow water
l
eve
l
(M
i
neeva & L
i
tv
i
nov, 1998). T
h
e
eff
ect o
f
warm weat
h
er on s
h
a
ll
ow
l

a
k
es
i
s part
i
cu-
l
arly strong whe n it coincides with low water level. It
i
sev
id
ent t
h
at t
h
ee
ff
ect o
f
water
l
eve
li
s
g
reater
in
s
h

a
ll
ow
l
a
k
es: t
h
ere
l
oa
di
ng o
f
p
h
osp
h
orus
f
rom t
h
e
sediment when the water is shallow is more intensive
b
ecause o
f
w
i
n

d
act
i
on, as o
b
serve
di
n storm
yd
a
y
s
in
La
k
eP
ihk
va
i
n August 2003 (persona
ld
ata). In
R
eyno
ld
san
d
Petersen (2000), t
h
e

di
rect re
l
at
i
ons
hip
between nutrients and ph
y
toplankton, primaril
y
c
y
a
-
n
o
b
acter
i
a,
i
s wea
k
an
d
nutr
i
ents are not an
i

ssue
w
h
en t
h
ep
h
ys
i
ca
l
requ
i
rements o
f
a
l
gae (water
temperature, insolation, water immobilit
y
) are satis
-
fi
e
d
. Nevert
h
e
l
ess, t

h
e connect
i
on
b
etween water
-
bl
oom
i
ng cyano
b
acter
i
aan
d
p
h
osp
h
orus
i
swe
ll
d
ocumented
.
L
on
g

-term investi
g
ations of Lake Peipsi (since
1
9
6
2) have shown that hi
g
hph
y
toplankton biomass
c
onverges with periods of low water level (Laugast
e
e
t al., 2001). Durin
gy
ears with maximal nutrient
l
oa
di
n
g
,as
i
nt
h
e 1980s, t
h
e

l
a
k
e was re
l
at
i
ve
ly
poo
r
i
n phytoplankton when there were high water levels
.
T
here was a more than sevenfold decrease in the
appli
cat
i
on o
f
m
i
nera
lf
ert
ili
zers
i
n Eston

i
a
b
etwee
n
the middle of the 1980s and the end of the 1990s
(
Leisk & Loigu, 2001). The external load enterin
g
Lake Pei
p
si from Estonian rivers decreased 2.4 times
f
or N (from 14.62 to 6.19 t yr
-
1
)
b
ut rema
i
ne
d
a
t
a
lmost the same level for P (from 199 to 196 t y
r
-
1
)

;
total point source loads were reduced by 42% fo
r
ni
tro
g
en an
d
21%
f
or p
h
osp
h
orus (Moura
d
et a
l
.
,
200
6
). The conce ntrations of nitrogen and phospho
-
rus mineral compounds in the River Velika
y
a on the
R
uss
i

an s
id
e
d
ecrease
df
rom 0.8 m
gl
-
1
(avera
g
e
d
over 1983–1991) to 0.37 (avera
g
e
d
over 1997–2001)
for nitrogen and from 0.032 to 0.020 for phosphorus
(No
g
es et al., 2004). Lon
g
-term datasets of nutrients
a
n
d
p
hy

top
l
an
k
ton popu
l
at
i
ons
i
nLa
k
ePe
i
ps
i
are
a
valuable resource for stud
y
in
g
the responses of
ph
ytop
l
an
k
ton to c
h

anges
i
n water
l
eve
l
an
d
water
t
emperature an
d
,
i
n part
i
cu
l
ar, t
h
e
i
mpact o
f
c
li
mate-
driven changes via nutrients on phytoplankton bio-
mass an
d

component
g
roups. T
h
ea
i
mo
f
t
hi
s wor
k
w
as to
f
o
ll
ow t
h
ee
ff
ects o
f
water
l
eve
l
an
d
temper

-
ature on nutrients and on phytoplankton and its majo
r
g
roups (
di
atoms, c
y
ano
b
acter
i
aan
d
cr
y
ptop
hy
tes
)
d
ur
i
ng two per
i
o
d
st
h
at

diff
ere
di
n water
l
eve
l
an
d
t
empera
t
ure.
S
tudy site
L
a
k
ePe
ip
s
i
s
.
l
. (3,558 k
m
2
, mean de
p

th 7.1 m),
l
ocate
d
on t
h
e
b
or
d
er o
f
Eston
i
aan
d
Russ
i
a,
i
st
h
e
l
argest transboundary lake in Europe. It consists of
t
hree parts that dif fer in trophic state: the moderatel
y
eutro
p

hic clear-water Lake Pei
p
si
s
.
s
. (2,
6
11 k
m
2
,
mean
d
ept
h
8.4 m, max
i
mum
d
ept
h
12.9 m), t
h
e
h
ighly eutrophic Lake Pihkva (708 k
m
2
,

mean dept
h
3.8 m, maximum de
p
th
5
.3 m), and the narrow Lake
La
mmija
r
v (23
6
k
m
2
,
mean depth 2.5 m, maximum
depth 15.3 m) connecting the former two. Lake
Pihkva is situated on the Russian border
,
and material
f
rom t
hi
s
l
a
k
e was on
ly

spora
di
ca
lly
ava
il
a
bl
e. La
k
e
Pe
i
ps
ii
swe
ll
m
i
xe
db
yt
h
ew
i
n
d
; no strat
ifi
cat

i
on o
f
t
emperature,
O
2
o
r
h
y
d
roc
h
em
i
ca
l
parameters occu
r
durin
g
the ice-free period. Water level is not
re
g
u
l
ate
d
;t

h
ere
f
erence water
l
eve
li
s 30 m a.s.
l.
(
200 cm accor
di
ng to t
h
e Mustvee
h
y
d
rometr
ic
station). Diatoms dominate in spring and autumn
,
a
nd also in summer in some
y
ears. Besides the lar
g
e
fil
amentous

f
orms o
f
Au
l
aco
s
eira i
sl
an
d
ic
a
(O
.
Mu
l
ler
)
Sim.
,
A.
g
ranulata
(
Ehr.
)
Sim. and
S
te

p
han
-
od
i
s
cu
s
bin
d
eranu
s
(Ku
t
z.) Krie
g
er, unicellular
centr
i
c spec
i
es (
g
enera Cyc
l
ote
lla
,
P
u

n
cticulata
,
S
tephanodiscus, C
y
clostephanos
)
and, to a lesse
r
e
xtent,
p
ennates such as
A
sterionella
f
ormosa Hass.
,
a
re also abundant. C
y
anobacteria
y
ield maximum
bi
omass
i
n summer an
d

autumn. A summer cyano
-
bacterial bloom occurs every year, even if the
weat
h
er
i
s coo
l
.T
h
e most consp
i
cuous
f
orms are
Gl
oeotric
h
ia ec
h
inu
l
ata
(
J. S. Sm
i
t
h)
P. R

i
c
h
ter
in
summer in Lake Peipsi
s
.s
.
and A
p
hanizomenon flos
-
aquae
(L.) Ra
lf
s
i
n autumn
i
nt
h
e sout
h
ern parts. T
h
e
genera
M
i

crocyst
i
s an
d
Ana
b
aen
a
a
re a
l
so
i
mportant
,
particularly since 2002.
4
H
y
drobiolo
g
ia (2008)
5
99:3–1
1
1
2
3
Materials and methods
Water samp

l
es
f
or nutr
i
ent ana
ly
s
i
s were co
ll
ecte
d
f
rom April–May to October–November 198
5
–200
5
.
Since 1992
,
all stations have been located in the
Eston
i
an area o
f
t
h
e
l

a
k
e, exce
p
t
f
or n
i
ne on t
he
R
ussian side, sampled in May 1992, October 2001
a
nd 2002 and Au
g
ust 2003–200
5
. Dependin
g
on th
e
y
ear, the number of samplin
g
sites varied from
5
to
32. T
h
ec

h
em
i
ca
l
compos
i
t
i
on o
f
t
h
e water (tota
l
p
hos
p
horus, P
t
o
t
; ort
h
op
h
osp
h
ate
i

on, P
O
4
-
P; tota
l
n
itrogen, N
t
o
t
;
ammonium ion
,
NH
4
-
N
;
nitrate ion
,
N
O
3
-N; n
i
tr
i
te
i

on, NO
2
-N (t
h
e
l
ast t
h
ree
j
o
i
ne
d
as
D
IN); an
d
s
ili
con, S
i
) was ana
l
yse
d
at t
h
e Inst
i

tute o
f
Z
oology and Botany during 1985–1992, and at Tart
u
Environmental Researchers Ltd, Estonia, durin
g
1
992–2005. The two laboratories mostl
y
emplo
y
ed
id
ent
i
ca
l
met
h
o
d
s
.
Summer (Jul
y
or Au
g
ust) ph
y

toplankton materia
l
c
overs the period 1985–1991. Monthl
y
samples wer
e
c
o
ll
ecte
df
rom May (Apr
il
) to Novem
b
er
i
n 1997–
200
5
. The methods for collectin
g
samples an
d
treatin
g
h
y
drochemical anal

y
ses are described i
n
detail in Mo
l
s et al. (199
6
). Ph
y
toplankton sample
s
were collected and treated by the same person during
the two
p
eriods; the methods are described i
n
Lau
g
aste et a
l
. (2001). In t
h
e present stu
dy
,t
h
e
following summer phytoplankton parameters were
a
nal

y
sed: Chl
a
,
total biomass
(
FBM
)
and the
bi
omasses o
f
c
y
ano
b
acter
i
a (CY),
di
atoms (BAC)
,
c
ryptophytes (CRYP), chlorophytes (CHL), dino
-
p
hytes (DINO) and chrysophytes (CHR)
.
Water tem
p

erature and water level data were
o
b
ta
i
ne
df
rom per
i
o
di
ca
li
ssues o
f
t
h
e
H
y
d
rometeoro
l
og
i
ca
l
Serv
i
ce an

df
rom t
h
e Inst
i
tut
e
o
f Meteorolo
gy
and H
y
drolo
gy
of the Estonia
n
Mi
n
i
str
y
o
f
Env
i
ronment. To exam
i
ne t
h
e

i
n
fl
uenc
e
of
water
l
eve
l
an
d
water temperature on nutr
i
ents
,
t
otal ph
y
toplankton and ph
y
toplankton
g
roups, w
e
distin
g
uished two time periods: 1985–1987 as th
e
hi

g
h
water
l
eve
l
per
i
o
d
an
d
2001–2003 as t
h
e
l
o
w
w
ater level
p
eriod. The latter
p
eriod was warmer,
espec
i
a
lly
t
h

e summers. Ta
bl
e1
ill
ustrates t
h
e sea-
sona
l
var
i
at
i
on o
f
water temperature an
d
water
l
eve
l
in Lake Peipsi for the two stud
y
periods. Fi
g
ure
1
presents the monthl
y
avera

g
e water levels for the
stu
dy
per
i
o
d
s.
S
tatistical method
s
All chemical, physical and plankton variables wer
e
l
o
g
-transformed to improve their statistical proper
-
ti
es. We use
d
genera
lli
near mo
d
e
lli
ng tec
h

n
i
ques
provided by SAS, Release 8.1 (SAS Institute Inc.,
1999), especiall
y
the MIXED and GLM procedures.
I
n calculating geometrical means, 95% tolerance
l
imits and differences between the periods or between
t
he
p
arts of Lake Pei
p
si, we used ANOVA, the
f
actors
b
e
i
ng per
i
o
d
,
l
a
k

e part an
d
t
h
ee
ff
ect o
f
t
h
e
i
r
i
nteract
i
on. To ana
l
yse seasona
li
ty, we use
d
a
l
arge
regression model developed by Mo
ls et al.
(
2004
)

and Mo
ls (2005). This mathematical model was
d
eve
l
ope
d
espec
i
a
ll
y
f
or La
k
ePe
i
ps
i
.It
h
as 7
0
parameters including square root of depth (m);
l
at
i
tu
d
e;

l
on
gi
tu
d
e; a s
i
x-component
b
eta-presenta-
ti
on
f
or year
l
y(
l
ong-per
i
o
d
)
d
epen
d
ence
t
ransformations of the year number a1–a6, wher
e
Table

1
M
ean
,
minimu
m
(min) and maximum (max
)
w
ater level and water
temperature at Mustvee
hydrometric station in Lak
e
P
e
i
ps
i
s.s.
d
ur
i
ng two
p
eriods, 198
5
–1987 and
2001
–
2003

R
eference water level is
30 m a.s.
l
. (200 c
m
a
ccording to the Mustve
e
h
y
d
rometr
i
c stat
i
on
)
1
98
5
–1987 2001–200
3
M
ea
n Min M
a
xM
ea
n Min M

ax
W
ater level
(
cm
)
M
a
y
246 208 277 208 138 24
1
Jul
y
–Au
g
ust 230 19
5
289 184 1
5
122
1
O
ctober–November 232 189 297 1
5
2 113 18
1
A
ll months 220 14
6
2

9
7 173 111 247
W
ater tem
p
erature
(
°
C)
M
a
y
9.0 0.2 19.8 12.2 2.3 1
6
.
2
July–August 18.2 12.7 23.1 21.5 14.0 27.4
O
ctober–November 4.6 0.1 12.1 4.0 0.1 10.
9
A
ll months 11.
30
.1 2
3
.1 1
3
.
50
.1 27.4

Hy
drobiolo
g
ia (2008)
5
99:3–11
5
1
23
a
i
=
N
((year-1920)/10;
N
N
l
i
,
1
.
4)
i
=
1
, 6) ( densit
y
function of the normal distribution)
,
l

i
=
{
3, 4.
5
,6,
7, 8, 8.4}; a t
h
ree-component
b
eta-presentat
i
on
f
o
r
seasonal de
p
endence, the ß-functions:
t
3
5
=
t
3
(
1–
t
)
5

,
t
44
t
t
=
t
4
t
(1
–
t
)
4
,
t
53
=
t
5
(1
-
t
)
3
,
where
t
=
n

u
m
be
r
of
d
ays in year/365; and a set-of-interactions term.
Water var
i
a
bl
es were pre
di
cte
df
or every 20
d
ays
i
n
a
year for each period. These predictions were used to
c
onstruct
g
rap
h
so
f
seasona

l
c
h
an
g
es w
i
t
h
t
h
e corre
-
spon
di
ng con
fid
ence
li
m
i
ts
.
Resul
t
s
N
utrient
s
C

ompar
i
son o
f
nutr
i
ent concentrat
i
ons
i
nt
h
e two
p
eriods revealed that the mean content of
P
tot
was
significantly higher during the low water level period
(2001–2003), and the increase was markedl
y
hi
g
her
in the shallower lakes La
mmija
rv an
d
P
ihk

v
a
(
Table 2
)
. Unlike
P
t
o
t
,
the concentration of
N
t
o
t
was
l
ower in the low water level
p
eriod, but the differ-
e
nces
i
n
N
tot
i
nt
h

es
h
a
ll
ower parts o
f
t
h
e
l
a
k
e were
n
ot stat
i
st
i
ca
ll
ys
i
gn
ifi
cant. T
h
e mass rat
i
oN
t

o
t
:P
t
o
t
was higher (21) for the high water level period than
f
or t
h
e
l
ow water
l
eve
lp
er
i
o
d
(14). T
h
e concentra
-
t
i
ons o
f
t
h

em
i
nera
lf
orms o
f
Pan
d
Ns
h
o
w
e
d
a
n
i
nverse tren
d
.A
l
t
h
oug
h
t
h
e mean va
l
ue o

f
P
O
4
-
P
f
o
r
the whole lake was sli
g
htl
y
hi
g
her in the hi
g
h water
l
eve
l
per
i
o
d
,t
hi
s
diff
erence was not stat

i
st
i
ca
lly
s
i
gn
ifi
cant. T
h
e mean concentrat
i
on o
f
DIN was
si
g
nificantl
y
hi
g
her in the low water level period
,
m
ainl
y
because of the hi
g
her content of NO

3
-N
;
fo
r
t
hi
s reason, t
h
e mass rat
i
o DIN:PO
4
-P was hi
g
her as
we
ll
.
The seasonal trends of P com
p
ounds in Lake
Pe
i
ps
i
s
.
s
. and Lake La

mmija
rv
i
nt
h
e two per
i
o
ds
w
ere s
i
m
il
ar: t
h
e nutr
i
ent content
w
as m
i
n
i
mum
f
ro
m
early spring to June, and thereafte r started to increase
t

owar
d
s autumn (F
ig
. 2). T
h
e
i
ncrease
i
nP
tot
an
d
P
O
4
-P starte
d
ear
li
er
wh
en t
h
e
w
ater
l
e

v
e
lw
as
l
o
w
and the summer warmer, and higher values of
p
h
osp
h
ates occurre
dd
ur
i
n
gl
ate summer an
d
autumn.
S
easona
lv
ar
i
at
i
ons
i

nN
tot
c
oncentrat
i
on
w
ere more
pronounce
di
nt
h
e
hi
g
h
water
l
eve
l
per
i
o
d
an
d
wer
e
s
y

nchronous in Lake Peipsi
s
.
s
. and Lake La
mmija
rv
(
F
ig
. 2). T
h
e max
i
mum N
tot
content
w
as esta
bli
s
h
e
d
i
n ear
l
y spr
i
ng, w

hil
e
i
ts m
i
n
i
mum content was
recorded in late June and Jul
y
. In contrast to
N
tot
,
no
t
rend was apparent in the seasonalit
y
of DIN durin
g
th
e
high
water
l
eve
l
per
i
o

d
(F
ig
. 2), w
h
ereas t
h
eDI
N
content during the low water level period was ver
y
h
i
g
h in earl
y
sprin
g
before the onset of the sprin
g
p
hy
top
l
an
k
ton
bl
oom.
Ph

y
toplankto
n
Significant differences between the two periods wer
e
noted in total summer biomass and Chl
a
a
s well as i
n
some p
h
ytop
l
an
k
ton groups. T
h
e
bi
omass an
d
C
hl
a
i
nt
h
e
l

ow water
l
eve
l
per
i
o
d
excee
d
e
d
t
h
e corre
-
sponding values in the high water level period two t
o
th
ree
f
o
ld
(Ta
bl
e2, F
ig
. 2). T
h
e most s

ig
n
ifi
can
t
(
t
h
ree to seven
f
o
ld) i
ncrease occurre
di
nCY
bi
omass
.
The biomass of BAC increased up to twofold;
h
owever, t
h
eu
pp
er
li
m
i
to
f

BAC
bi
omass was
th
ree
f
o
ld l
ower
d
ur
i
ng t
h
e
l
ow water
l
eve
l
per
i
o
d
.
Among t
h
em
i
nor groups, t

h
e growt
h
o
f
DINO (3–4
ti
mes) was qu
i
te mar
k
e
d
.As
ig
n
ifi
cant
d
ecrease (3–4
ti
mes) was o
b
serve
di
n CRYP
bi
omass; t
h
e

d
ecrease
i
n CHL
i
n some parts o
f
t
h
e
l
a
k
e was
l
ess s
i
gn
ifi
cant
.
The
p
arts of the lake that differed in tro
p
hic state also
diff
ere
di
nt

h
ec
h
an
g
es
i
np
hy
top
l
an
k
ton
g
roups. T
h
e
i
ncreases
i
n tota
lbi
omass, C
hl
a
,
CY an
d
DINO

in
the low water level
p
eriod were most
p
ronounced i
n
t
h
e sout
h
ern parts. Water transparenc
ydi
m
i
n
i
s
h
e
d
about 1.5 times in Lake La
mmija
r
v and Lake Pihkva
i
n the second period. A growth in diatom biomass
was obvious in the northern
p
art, Pei

p
s
i
s
.
s
.,
whil
e
t
h
ere was even some
d
ecrease
i
nt
h
e sout
h
ern parts
.
T
he biomass of cryptophytes diminished most i
n
Lake Pihkva, about ei
g
ht times (in Lake Peipsi
s
.
s

.
and Lake La
mmija
rv a
b
out t
h
ree t
i
mes
).
Fi
g.
1
M
ean water level in Lake Pei
p
s
i
s
.
s
f
. during periods o
f
high (1985 1987) and low (2001 2003) water levels
high (1985
–
1987) and low (2001
–

2003) water levels
6
H
y
drobiolo
g
ia (2008)
5
99:3–1
1
1
2
3
C
hlorophytes maintained their quantity in Lak
e
P
e
ip
s
i
s
.
s
.
but declined 2.
5
–
3
times in the souther

n
parts o
f
t
h
e
l
a
k
e
.
Some p
h
ytop
l
an
k
ton groups revea
l
e
d
s
i
gn
ifi
cant
P
earson correlations (lo
g
arithmic values

,
P
\
0
.0001) with nutrients and water tem
p
erature
:
CY w
i
t
h
tota
l
P
(
r
= 0.52), DIN:P
O
4
-
P
(
r
=
-0.35)
,
N
tot
:

P
tot
(
r
=
-
0
.
33)
,N
O
3
-N
(
r
=-
0.31) an
d
wate
r
t
emperature at t
h
et
i
me o
f
samp
li
ng

(
r
=
0
.47
)
;BA
C
w
ith P
t
o
t
(
r
=
0.36
)
,PO
4
-P
(
r
=
0.33
)
and wate
r
T
ab

l
e2
Nutr
i
ents (tota
lph
os
ph
orus: P
tot
;
ort
h
o
ph
os
ph
ate
i
on
:
PO
4
-P; tota
l
n
i
trogen:
N
t

o
t
;
ammon
i
um
i
on: N
H
4
-
N
;
n
i
trate
i
on
:
N
O
3
-
N; n
i
tr
i
te
i
on: N

O
2
-N (t
h
e
l
ast t
h
ree com
bi
ne
d
as DIN)
;
a
nd silicon: Si), transparenc
y
(Secchi), chloroph
y
l
l
a
(Ch
l
a
)
a
n
d
p

hy
top
l
an
k
ton (tota
lbi
omass (FBM),
bi
omasses o
f
cy
ano
b
acter
i
a (CY),
di
atoms (BAC), cr
y
ptop
hy
tes (CRYP),
c
hlorophytes (CHL), dinophytes (DINO) and chrysophytes
(
CHR)
i
n water
i

nLa
k
ePe
i
ps
i
an
di
ts t
h
ree parts
d
ur
i
ng
periods of hi
g
h (198
5
–1987; period 1) and low (2001–2003
;
per
i
o
d
2 ) water
l
eve
ls
V

ariable Unit Period N Mean 95% tolerance limits Lake Peipsi
s
.
s.
Lake La
mmija
r
v Lake Pihkva
P
t
o
t
mg
Pm
-
3
1
471 40* 14 118 32* 5
9
* 64*
2
129 53 17 161 41 91 138
PO
4
P
m
g
P
m
-

3
1
222 13 2 92 10 19 18*
2
129 10 2
6
2 7 18 4
6
N
t
o
t
mg
N
m
-
3
1
466 841* 336 2107 756* 1080 104
2
2
129 712 375 1351 642 933 963
D
IN m
g
Nm
-
3
1
222 4

5
*8 2
5
4 44*
5
9* 4
5
*
2
12
9
110 2
9
412 10
6
12
6
108
N
tot
:P
tot
1
4
6
1 21*
6
72 24* 1
8
*1

6
*
2
129 14 6 33 1
5
10 7
D
IN:PO
4
1
243 3.3 0.2 45.8 3.5 3.1 2.
9
2 129 11
.
2 1 104 14
.7 7
2
.
3
Si m
gl
-
1
1 233 0
.
80
.
23
.
80

.7
10
.
9*
2
12
9
0.8 0.1 8.1 0.7 0.7 1.
9
Secchi m 1 718 1.6* 0.7 3.7 1.8 1.2* 1.1*
2
122 1.4 0.
5
3.6 1.7 0.9 0.
7
Chl
a
m
g
m
-
3
1
488 12.6* 2.
5
64.1 11.4* 12.
9
* 17.2
*
2

132 23.7 7.2 78.1 20.1 35 44.
8
FBM
gm
-
3
1
101 3.4* 0.3 34.5 2.5* 8.5
9
.8
2
77 9.2 2.6 33 7.
5
14.3 22.
1
CY
g
m
-
3
1
84 0.40* 0.02 10.04 0.24* 1.
5
2* 1.
5
2
*
2
77 3.86 0.25 5
9

.0
9
2.8
9
7.55 13.1
9
B
A
Cg
m
-
3
1
90 1.07 0.02 60.71 0.60* 4.08 6.37
2
77 2.
06 0
.14
30
.
3
71.
58 3
.
83 5
.
68
C
HL g m
-

3
19
0 0.18* 0.02 1.8 0.13 0.54* 0.5
2
2
77
0
.1
50
.
03 0
.
86 0
.14
0
.17
0
.2
1
CHR
g
m
-
3
1550
.
00
4
00
.

0
7
60
.
003 0
.
0
11
0
.
0
11
2
54 0.025 0.003 0.20
9
0.025 0.022 0.02
9
C
RYP
g
m
-
3
18
1
0
.44*
0
.
03 5

.7
50
.4
5
*
0
.
33
*
0
.42
*
2
77
0
.14
0
.
0
2 1.1
50
.1
50
.12
0
.
05
D
INO g m
-

3
1
45 0.05 0 0.76 0.06 0.03 0.05
*
2
46 0.18 0.01 3.
5
6 0.16 0.12 1.9
1
*
The
g
eometrical means of the first and second periods are si
g
nificantl
y(
P
\
0.0
5)
differen
t
Hy
drobiolo
g
ia (2008)
5
99:3–11
7
1

23
temperature at t
h
et
i
me o
f
samp
li
ng (
r
=-
0.35).
C
ryptophytes showed no correlation with nutrients
.
Weak
p
ositive correlations a
pp
eared between CRYP
a
n
d
water
l
eve
l
,an
db

etween CRYP an
dN
tot
:P
tot
,
w
hil
e negat
i
ve corre
l
at
i
ons occurre
db
etween BA
C
a
nd
N
t
o
t
:
P
t
o
t
.

D
iscussion
Asu
b
stant
i
a
l diff
erence
i
n
b
ot
h
p
h
ys
i
coc
h
em
i
ca
l
p
arameters and phytoplankton between the high and
low water level periods was recorded in our stud
y
.On
th

e
b
as
i
so
fl
ong-term
d
ata
f
or La
k
ePe
i
ps
i
, a wate
r
i
Fig
.
2
S
easona
l
patterns o
f
n
utr
i

ents (tota
lph
os
ph
orus:
P
t
o
t
;
ortho
p
hos
p
hate ion:
PO
4
P
; tota
l
n
i
tro
g
en: N
tot
;
a
mmonium ion; NH
4

N;
ni
trate
i
on: N
O
3
N;
n
i
tr
i
t
e
i
on: N
O
2
-N
(
the last thre
e
com
bi
ne
d
as DIN
)
;an
d

N
tot
:
P
tot
mass rat
i
o) an
d
chloroph
y
l
l
a
in Lake Pei
p
s
i
s
.s
. and Lake La
mmija
r
v
durin
g
periods of hi
gh
(
1985–1987

)
and lo
w
(2001–2003) water
l
eve
l
s
.
P
redicted mean and
9
5
%
con
fid
ence
li
m
i
ts
f
or t
he
true value are estimated b
y
m
at
h
emat

i
ca
l
mo
d
e
l
described in the
p
art of
stat
i
st
i
ca
lm
et
h
ods
8
H
y
drobiolo
g
ia (2008)
5
99:3–1
1
1
2

3
c
ondition factor (WCF) combinin
g
water temperatur
e
and water level was developed by To
nu Mo
l
s
(
M
ili
us
e
t al., 200
5)
. In the WCF, water level had a more
m
arked effect on nutrients than water tem
p
erature.
Th
eP
tot
concentrat
i
on s
h
owe

d
an
i
nverse re
l
at
i
ons
hi
p
w
i
t
h
water
l
eve
l
;
i
t was
hi
g
h
er w
h
en t
h
e water
l

eve
l
was lower. The influence of water level on
N
t
o
t
c
ontent was
p
os
i
t
i
ve an
d
somew
h
at
l
ess mar
k
e
d
t
h
an
o
n
P

tot
.T
h
ee
ff
ects o
fw
ater
l
e
v
e
l
an
dw
ate
r
temperature on PO
4
-
Pan
d
DIN were a
l
so oppos
i
te
.
T
he resu lts of the present stud

y
were entirel
y
c
ons
i
stent
wi
t
h
t
h
ose
d
ata
.
I
n an earlier article (Milius et al., 2005), w
e
app
lied a classical canonical model without consid
-
e
r
i
n
g
seasona
l
e

ff
ects;
i
nt
hi
s stu
dy
, we exam
i
ne
d
t
h
e
seasona
li
ty o
f
nutr
i
ents. T
h
e regu
l
ar
i
ncrease
i
nP
c

ontent durin
g
summer is characteristic of shallow
productive water bodies with intermittent mixin
g
i
n
t
h
e summer season (Prepas & Trew, 1983; Carva
lh
o
& Kirika, 2003; Søndergaard et al., 2003). The
seasonal
p
atterns of
N
t
o
t
a
nd DIN were different.
According to Prepas & Trew (1983), inorganic
N
d
oes not
f
o
ll
ow t

h
e same pattern as N
t
o
t
. Pettersso
n
e
ta
l
. (2003) compare
d
t
h
e seasona
li
ty o
f
nutr
i
ent
s
a
nd chlorophyll in Lake Erken in cold and warm
p
er
i
o
d
s, an

df
oun
d
e
l
evate
dph
os
ph
ate, ammon
i
u
m
a
n
d Chl
a
l
eve
l
s
i
nt
h
e warm per
i
o
dd
ur
i

ng August
a
n
di
n autumn. T
h
e aut
h
ors exp
l
a
i
nt
h
ese resu
l
ts
by
the increasin
g
activit
y
of bacteria, which increase
s
t
h
e upta
k
eo
f

ox
yg
en an
d
t
h
ere
l
ease o
f
p
h
osp
h
ate
a
n
d
ammon
i
um
f
rom se
di
ment
i
nto t
h
e
w

ater.
C
omparison of our data with their
g
raphs shows tha
t
t
h
e
dy
nam
i
cs o
f
P
O
4
-P and Chl
a
fit t
h
e data
p
resented b
y
Pettersson et al. (2003) closel
y
, while
the earlier increase in P
O

4
-
P
i
sre
l
ate
d
to t
h
ea
b
senc
e
o
f permanent stratification in the lake. As a result o
f
water mixin
g
, the PO
4
-
Pi
o
n
s
r
e
l
eased

fr
o
mfr
es
h
se
di
ments are transporte
d
to t
h
ep
h
ot
i
c zone, w
hi
c
h
ren
d
ers t
h
e cont
i
nuat
i
on o
f
p

h
otosynt
h
es
i
s poss
ibl
e.
I
n Lake Peipsi, the higher values of DIN during the
l
ow water
l
eve
l
per
i
o
d
were
d
ue to t
h
e
high
er conten
t
o
f
n

i
trates, not ammon
i
um, ev
id
ent
l
y resu
l
t
i
ng
f
rom
m
ore intensive bacterial nitrification. An increase i
n
N
O
3
-N is characteristic of all
p
arts of the lake.
I
n terms o
f
mean va
l
ues,
P

tot
h
as
i
ncrease
din
recent years, especially in Lake La
mmija
rv and Lak
e
P
ihkva (Kan
g
ur et al., 2003). The polarit
y
of Lak
e
P
ei
p
si has increased more with res
p
ect of P
tot
t
h
a
n
to
N

tot
(Kangur & Mo
l
s, t
hi
s
i
ssue). In s
h
a
ll
ow
l
a
k
es
,
s
ummer P concentrations are largely controlled by
i
nterna
l
processes, an
d
Pre
l
ease
f
rom se
di

ment
i
nto
l
a
k
e water
d
epen
d
sont
h
ese
di
ment sur
f
ace:wate
r
column ratio
,
which means that it is more intensive in
l
ar
g
ean
d
s
h
a
ll

ow
l
a
k
es (Søn
d
er
g
aar
d
et a
l
., 2003).
T
hi
s
i
s con
fi
rme
db
yt
h
e
i
ncrease
i
nt
h
e tota

l
an
d
mineral phosphorus values; also, the N:P ratio
d
ecrease
d
muc
h
more
i
nt
h
es
h
a
ll
o
w
er La
k
eP
ihkva
th
an
i
nLa
k
ePe
i

ps
i
s
.
s
.
(Ta
bl
e 2). In t
h
es
h
a
ll
ower
p
art, p
h
osp
h
orus re
l
oa
di
ng
f
rom se
di
ment w
h

en t
he
w
ater level is low is also more intensive owin
g
t
o
wi
n
d
act
i
on, as o
b
serve
di
nLa
k
eP
ihk
va on storm
y
d
ays
i
n August 2003.
Th
eco
n
ce

n
t
r
at
i
o
n
so
f
t
h
e
min
e
r
a
lf
o
rm
so
f
n
i
tro
g
en an
d
p
h
osp

h
orus excee
d
e
d
t
h
eva
l
ues t
h
at
li
m
i
tt
h
e growt
h
o
f
p
h
ytop
l
an
k
ton groups. Accor
d-
in

g
to Wilander & Persson (2001), N-deficienc
y
appears at a DIN concentrat
i
on o
f
30 m
g
N
m
-
3
o
r
l
ower. Onl
y
in Lake Peipsi
s
.
s
. did the lowest value
s
t
emporar
il
y approac
h
t

hi
s
li
m
i
t(
d
escr
ib
e
db
y Gam-
meter & Zimmermann
,
2000
;
Dokulil & Treubner
,
2
000
)
. The ratio DIN:PO
4
-P should be more directl
y
re
l
ate
d
to p

hy
top
l
an
k
ton t
h
an t
h
e rat
i
oo
f
tota
l
Nt
o
t
ota
l
P. A
l
t
h
oug
h
ammon
i
aan
d

n
i
trate-N ar
e
associated in opposite ways with water level and
t
em
p
erature, t
h
e corre
l
at
i
ons
b
etween DIN an
d
p
h
ytop
l
an
k
ton were stronger t
h
an t
h
ose
b

etween
N
tot
a
n
d
p
h
ytop
l
an
k
ton. T
h
e rat
i
oo
f
t
h
em
i
nera
l
f
orms of N to P was hi
g
her durin
g
the low wate

r
l
eve
l
per
i
o
d
,an
d
t
h
ere was an
i
ncreas
i
n
gd
om
i
nanc
e
of
cyano
b
acter
i
at
h
at are una

bl
eto
fi
x
N
2
(
spec
i
es o
f
M
icroc
y
sti
s
)
. In most articles,
p
hos
p
horus and the
N
:P ratio are re
g
arded as crucial, while weake
r
corre
l
at

i
ons
h
ave
b
een
f
oun
d
w
i
t
h
tota
l
n
i
tro
g
en an
d
its mineral forms. Similarly, in our study, correla-
t
ions with nitro
g
en were weak or absent. In
g
eneral,
C
RYP and CHL prefer a hi

g
her nitro
g
en content
and N:P ratio (Planas, 1991; Wilk-Woz
´
ni
a
k
&
Lige
˛za, 2003); this may explain the decrease in
e
e
b
iomass of these
g
roups durin
g
the low water leve
l
per
i
o
d
.T
h
e
l
ow a

b
un
d
ance o
f
CY
i
nt
h
e 1980s was
predictably related to the high N:P ratio in thi
s
period (No
g
es et a
l
., 2004). Our ear
li
er resu
l
t
s
s
h
owe
d
t
h
at t
h

e
hi
g
h
rat
i
o was c
l
ear
l
y cause
dby
the high water level, besides the high external loa
d
(No
g
es et a
l
., 2003). On t
h
eot
h
er
h
an
d
,t
h
e
l

ow N:
P
rat
i
ova
l
ues
i
nt
h
e secon
d
per
i
o
d
were not on
l
y
d
u
e
to t
h
ere
d
uce
d
externa
ll

oa
db
ut a
l
so to t
h
e
l
owe
r
w
ater le
v
el in combination
w
ith
w
arm summers.
Hy
drobiolo
g
ia (2008)
5
99:3–11
9
1
23
As a rule, water qualit
y
deteriorates durin

g
the
warm per
i
o
d
(Pettersson et a
l
., 2003; Søn
d
ergaar
d
e
t al, 2003). One should kee
p
in mind the differen
t
seasonal d
y
namics of water temperature in differen
t
years: years w
i
t
h
s
i
m
il
ar mean water temperature

s
m
ay have very different seasonal temperatures, which
c
ause, e.
g
. the domination of diatoms in cool
summers an
d
cyano
b
acter
i
a
i
n warm autumns. Carv-
alh
oan
d
K
i
r
ik
a (2003)
f
oun
d
no re
l
at

i
ons
hi
p
b
etwee
n
phytoplankton Chl
a
content and annual mean wate
r
temperature. On t
h
eot
h
er
h
an
d
, spr
i
n
g
water tem
-
perature
h
as a strong e
ff
ect on summer c

h
em
i
ca
l
c
onditions (George et al., 2000), and phytoplankto
n
bi
omass
i
n summe r
d
epen
d
sont
h
e tota
l
P content
in
spr
i
ng (Krzywosz, 1999). However, corre
l
at
i
ons
between water temperature in spring and nutrient
s

i
n summer were ver
y
wea
ki
nLa
k
ePe
i
ps
i
(
r
=
0
.
2);
a
s
f
or t
h
ep
h
ytop
l
an
k
ton groups, on
l

y a wea
k
pos
i
t
i
v
e
e
ff
ect on CY was revea
l
e
d(
r
=
0
.26
,
P
\
0
.0001
)
.
Water temperature at the samplin
g
time showe
d
s

ig
n
ifi
cant pos
i
t
i
ve corre
l
at
i
ons w
i
t
h
t
h
e
bi
omass o
f
C
Yan
d
CRYP, an
d
a negat
i
ve corre
l

at
i
on w
i
t
h
d
iatoms
.
Dom
i
nance o
fdi
atoms
i
s more assoc
i
ate
dwi
t
h
s
ili
ca. However, we
f
oun
d
no corre
l
at

i
on w
i
t
h
s
ili
co
n
in Lake Pei
p
si, where the mean silicon conten
t
exceeded the limitin
g
value of 0.5 m
g
l
-
1
reporte
din
t
h
e
li
terature (Wetze
l
, 2001). T
h

e
l
ower s
ili
con:n
i
tro
-
g
en mass ratio for the southern parts was obviousl
y
i
nte
g
ra
l
to t
h
e
d
ecreas
i
n
gdi
atom
bi
omass (Ta
bl
e2)
.

Th
e
i
ncrease
i
n
di
no
fl
age
ll
ate
bi
omass
i
nt
h
e
l
o
w
water level period is possibl
y
also related to th
e
h
i
g
her P content. A parallel d
y

namics of DINO an
d
C
Y
i
n
l
a
k
es
i
n Great Br
i
ta
i
n was stresse
dby
Fo
gg
(
196
5)
.
On the basis of the water condition factor (WCF)
,
C
Y were most stron
gly
a
ff

ecte
dby
weat
h
er, w
hile
FBM, BAC and CRYP were less affected
(
Miliu
s
e
t al., 200
5
). Water temperature at the samplin
g
time
was t
h
e most
i
mportant
f
actor
f
or c
y
ano
b
acter
i

aan
d
d
iatoms (opposite for CY and BAC), and water level
for CRYP. It was obvious that cyanobacteria and th
e
N:P rat
i
o
f
o
ll
owe
d
oppos
i
te courses. Water
l
eve
lin
t
h
e prev
i
ous year
di
sp
l
aye
d

strong negat
i
ve corre
l
a-
tions with the mineral forms of N and P. When th
e
parts o
f
t
h
e
l
a
k
e were compare
d
,t
h
e corre
l
at
i
ons
b
etween t
h
e WCF an
d
correspon

di
ng p
h
ytop
l
an
k
to
n
v
alues were evidently stronger in Lake Pihkva an
d
Lake La
mmija
r
vt
h
an
i
nLa
k
ePe
ip
s
i
s
.
s.
C
onclus

i
on
s
Data from two periods with different external nutrient
l
oa
d
an
d
water
l
eve
li
nLa
k
ePe
ip
s
id
emonstrate
d
t
h
e
synerg
i
st
i
ce
ff

ect o
f
water
l
eve
l
an
d
water tempera-
ture on nutr
i
ents an
d
,v
i
a nutr
i
ents, on p
h
ytop
l
an
k
ton.
I
nt
h
e per
i
o

d
o
f high
externa
l
Nan
d
P
l
oa
d
,
high
w
ater levels and cool summers (1985–1987), there
w
ere
hi
g
h
er va
l
ues o
f
N
t
o
t
a
nd a higher

N
t
o
t
:P
t
o
t
mass
rat
i
o. T
h
e per
i
o
d
w
i
t
hl
ower water
l
eve
l
an
d
warmer
summers (2001–2003) was c
h

aracter
i
ze
db
y
hi
g
h
er
P
t
o
t
c
ontent
,
lower
N
t
o
t
:P
t
o
t
m
ass ratio and higher
DIN:P
O
4

-P mass rat
i
o, an
d by high
er C
hl
a
content,
p
h
ytop
l
an
k
ton an
d
cyano
b
acter
i
a
lbi
omass an
dl
owe
r
w
ater transparency. An
i
ncreas

i
ng
d
om
i
nance o
f
t
h
e
c
y
anobacteria that cannot fix
N
2
(
s
p
ecies o
f
M
ic
r
o-
c
ystis
)i
nt
h
e

l
ow water per
i
o
d
ma
yb
e exp
l
a
i
ne
dby
t
h
e
hi
g
h
er rat
i
oo
f
t
h
em
i
nera
lf
orms o

f
NtoP
i
nt
hi
s
p
eriod. The effect of water level and of the mechan-
ical influence of the wind and waves was stron
g
er i
n
t
h
es
h
a
ll
owest part, La
k
eP
ihk
va. Our stu
di
es con-
fi
rmed that lower water levels and warmer summers
resulted in a deterioration of water qualit
y
in spite of

t
h
e
d
ecreas
i
n
g
externa
ll
oa
d.
Acknowled
g
ements
Th
e researc
h
was supporte
db
yt
he
E
stonian tar
g
et financed pro
j
ect SF 03
6
2483s03 and th

e
E
stonian Science Foundation (grants
6
008,
6
820). Data from
t
he Estonian State monitorin
g
pro
g
ramme were used in this
s
tudy. We are indebted to Mrs. Ester Jaigma for revising th
e
E
ng
li
s
h
text o
f
t
hi
s art
i
c
l
e. T

h
e contr
ib
ut
i
on o
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h
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g
reatl
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arva
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i
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okulil, M. T. & K. Treubner, 2000. C
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na
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arge s
h
a
ll
ow temperate
l
a

k
e. Hy
d
ro
bi-
o
lo
g
ia,
5
06–
5
09: 2
5
7–263
.
No
ges, T., I. To
n
no, R. Laugaste, E. Lo
i
gu & B. S
k
a
k
a
l
s
ki,
2

004. T
h
e
i
mpact o
f
c
h
an
g
es
i
n nutr
i
ent
l
oa
di
n
g
on
c
yanobacterial dominance in Lake Peipsi (Estonia/Rus
-
sia). Archiv Fu
r Hydrobiologie 1
6
0: 2
6
1–279

.
P
adisak, J. & I. Koncsos, 2002. Trend and noise: lon
g
-term
ch
anges o
f
p
h
ytop
l
an
k
ton
i
nt
h
e Keszt
h
e
l
y Bas
i
no
f
La
k
e
Ba

l
aton, Hun
g
ar
y
. Ver
h
an
dl
un
g
en
d
er
i
nternat
i
ona
l
e
n
Vereinigung fu
r Limnolo
g
ie 28: 194–203.
P
ettersson, K., K. Grust, G. We
yh
enme
y

er&T.B
l
enc
k
ner
,
2
003. Seasonalit
y
of chloroph
y
ll and nutrients in Lake
E
rken – effects of weather conditions. Hydrobiologia:
5
06–
5
09
,
7
5
–81.
P
lanas, D., 1991. Factors controlling phytoplankton commu
-
ni
ty structure
i
nana
lk

a
li
ne versus so
f
twater
l
a
k
e.
Oecolo
g
ia aquatica 10: 9
5
–111.
P
repas, E. E. & D. O. Trew, 1983. Eva
l
uat
i
on o
f
t
h
ep
h
os
-
phorus–chlorop
y
ll relationship for lakes of the

P
recambrian
S
hield in Western
C
anada.
C
anadian
J
ournal
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f Fisheries and Aquatic Sciences 40: 27–35
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R
eynolds, C. S. & A. C. Petersen, 2000. The distribution o
f
p
l
an
k
ton
i
c Cyano
b
acter
i
a
i
nIr
i

s
hl
a
k
es
i
nre
l
at
i
on to t
h
e
i
r
t
rophic states. H
y
drobiolo
g
ia 424: 91–99.
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S
Inst
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tute Inc., Car
y.
Sønder
g
aard, M., J. P. Jensen & E. Jeppesen, 2003. Role o

f
se
di
ment an
di
nterna
ll
oa
di
ng o
f
p
h
osp
h
orus
i
ns
h
a
ll
o
w
lakes. H
y
drobiolo
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5
09: 13
5
–14
5.
Wetze
l
, R. G., 2001. L
i
mno
l
ogy.
l
a
k
ean
d
r
i
ver ecosystems,
3
r
d
e
d
n. Aca
d
em
i
c Press, USA.

Wilander, A. & G. Persson, 2001. Recover
y
from eutrophica
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ti
on: exper
i
ences o
f
re
d
uce
d
p
h
osp
h
orus
i
nput to t
h
e
f
our
lar
g
est lakes of Sweden. Ambio 30: 47
5
–48
5

.
Wilk-Woz
´
niak; E. & S. Lige
˛za, 2003. Phytoplankton–nutrient
e
e
re
l
at
i
ons
hi
ps
d
ur
i
ng t
h
e ear
l
y spr
i
ng an
d
t
h
e
l
ate autum

n
i
n shallow and polluted reservoir. Oceanological an
d
Hydrobiological Studies 32: 7
5
–87.
Hy
drobiolo
g
ia (2008)
5
99:3–11
11
1
23
ELL
S 200
7
Pollen, d
i
atom and plant macro
f
oss
i
l assemblages
i
nd
i
cate a

low water level phase of Lake Peipsi at the be
g
innin
g
of th
e
Holocene
T
ii
t Han
g
Æ
Æ
V
oll
i
Kalm
Æ
Æ
Ke
r
s
t
i
K
i
hn
o
Æ
Æ

Martynas Milkevic
ˇ
i
us
Ó
S
pringer Science+Business Media B.V. 200
7
Abs
tr
ac
t Durin
g
the Fennoscandian ice recessio
n
f
rom t
h
e eastern Ba
l
t
i
c area, t
h
e water
l
eve
li
nt
h

e
Lake Peipsi basin was decreasing and reached
a
m
inimum at the end of the Youn
g
er Dr
y
as Chro-
n
ozone. T
h
e
l
ow
l
a
k
e
l
eve
l
e
pi
so
d
e
i
sre
p

resente
din
the basal deposit s by a ca. 0.8 m thick bed of coars
e
d
etritus
gy
tt
j
a dated to 9.6–9.1 k
a
14
C
BP. Th
e
gy
tt
j
a
li
es at an e
l
evat
i
on o
f
20–21 m a.s.
l
.,
i

.e
.
ab
out 9 m
b
e
l
ow t
h
e present
l
a
k
e
l
eve
l
(30 m a.s.
l
.)
,
a
nd is buried under a 1.
5
–2 m bed of fine to
m
e
di
um-
g

ra
i
ne
d
san
d
.T
h
e overa
ll
po
ll
en
d
at
a
i
n
di
cate a s
h
a
ll
ow-water
li
ttora
l
env
i
ronment

d
ur
i
n
g
t
h
e gytt
j
a accumu
l
at
i
on
i
nt
h
e area stu
di
e
d
.T
h
e
d
iatom flora in the
gy
tt
j
a is dominated b

y
shallow
-
water
b
ent
hi
can
d
ep
i
p
hy
t
i
c taxa,
i
n
di
cat
i
n
g
eutro-
p
hi
c
li
ttora
l

con
di
t
i
ons at t
h
et
i
me o
f
gytt
j
a
a
ccumulation. In the uppermost port ion of the
gy
tt
j
a
se
q
uence t
h
e
p
o
ll
en an
ddi
atom success

i
ons
i
n
di
cat
e
as
h
ort per
i
o
d
o
fl
an
d
emer
g
ence w
h
en swamp
y
con
di
t
i
ons preva
il
e

di
nt
h
e surroun
di
ngs.
K
eywor
ds
D
i
atoms
Á
Po
ll
en
Á
Pl
ant macro
f
oss
ils
Á
L
a
k
ePe
i
ps
i

Á
B
ur
i
e
d
organ
i
c
b
e
d
s
Á
L
ake level chan
ge
Á
E
arl
y
Holocen
e
I
ntroduct
i
o
n
On the basis of palynological (Sarv & Ilves, 1975
;

H
ang et al., 199
5
, 2001) and geomorphologica
l
(Hang et al., 1964; Raukas & Ra
h
ni, 1969; Han
g&
Miid
e
l
, 1999)
d
ata, a
l
ow water p
h
ase
i
nt
h
e ear
l
y
H
o
l
ocene
d

eve
l
opment o
f
La
k
ePe
i
ps
i
(F
i
g. 1)
h
as
b
een inferred. The early palynological evidence
concerne
d
t
h
e surroun
di
n
g
wet
l
an
d
s (Sarv & I

l
ves,
1975) and suggested that the lowest water level
o
ccurred at the beginning of the Preboreal Chronoz
-
o
ne
(
s
en
s
u
s
tr
i
ct
o
,
Man
g
eru
d
et a
l
., 1974). Mor
e
recent researc
h
(Hang et a

l
., 2001)
h
as s
h
own t
h
at
t
he lake level may already have been 10 m below the
current water ta
bl
e (30 m a.s.
l
.) at t
h
een
d
o
f
t
h
e
Y
ounger Dryas C
h
ronozone. Recent
l
ywe
di

scovere
d
a
l
ayer o
f
coarse
d
etr
i
tus gytt
j
a
i
nt
h
e sout
h
-western
part of the basin of Lake Peipsi proper (Fi
g
.1)
,
l
ocate
d9
.2–8.2 m
b
e
l

ow t
h
e current mean water
l
eve
l
an
db
ur
i
e
d
un
d
er a san
dl
ayer. Po
ll
en,
di
atom an
d
plant mac rofossil anal
y
ses of the
gy
tt
j
ala
y

er revea
l
an extreme
ly l
ow water
l
eve
l
per
i
o
d
at t
h
et
i
me o
f
t
h
e
g
ytt
j
a accumu
l
at
i
on. T
h

e new
bi
ostrat
i
grap
hi
c
d
ata
Guest editors: T. No
ges, R. Eckmann, K. Kangur, P. No
ges
,
A. Reinart, G. Roll, H. Simola & M. Vil
j
anen
European Large Lakes—Ecosystem changes and thei
r
eco
l
og
i
ca
l
an
d
soc
i
oeconom
i

c
i
mpact
s
T
. Hang
(
&
)
Á
V
.Ka
l
m
Á
M. Milkevic
ˇ
ius
I
nstitute of Geolo
gy
, Universit
y
of Tartu, Vanemuise 46,
T
artu 51014
,
Estonia
e-ma
il

:T
ii

e
K
.K
ih
n
o
D
epartment of History, University of Tartu, Lossi 3
,
T
artu 51003
,
Estonia
1
23
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
D
OI 10.1007/s107
5
0-007-920
5

-
z
a
nd a s
y
nthesis of earlier research enable us to revise
t
h
e
p
rev
i
ous env
i
ronmenta
l
reconstruct
i
ons o
f
La
k
e
P
e
i
ps
i
at
i

ts
l
owest
l
eve
l
at t
h
e
b
e
gi
nn
i
n
g
o
f
t
h
e
H
olocene
.
L
ake Pei
p
si (30 m a.s.l.) is a rather shallow lak
e
with a mean water depth of about 8 m (max 15 m). It

o
ccupies a
5
0–60 m deep glacially eroded bedrock
d
e
p
ression (Miidel et al
.
, 2001). The se
q
uence o
f
l
acustr
i
ne se
di
ments
i
nt
h
e
l
a
k
e
d
epress
i

on
b
e
gi
n
s
with annually laminated or homogenous glaciolacus-
trine clay up to 10 m thick. The clay is covered by
a
c
alcareous
gy
tt
j
ala
y
er, the thickness of which varie
s
f
rom about 2 cm to 1.9 m, followed by
5
m thic
k
pure gyttja layer. In the southern part of Lake Peips
i
p
roper (F
ig
.1)t
h

e
l
a
k
e
b
ottom
i
s at present covere
d
b
y a ca. 2 m thick fine to medium-grained lacustrin
e
s
and (Han
g
et al., 2001). This sand covers the coars
e
d
etr
i
tus
gy
tt
j
a
l
a
y
er

di
scusse
di
nt
h
e current art
i
c
l
e,
w
hich according to AMS
14
Cd
ates accumu
l
ate
d
a
round 9.6–9.1 ka
14
C
BP.
In the central part of Lake Peipsi proper the
t
rans
i
t
i
on

f
rom
gl
ac
i
o
l
acustr
i
ne c
l
a
y
stoHo
l
ocen
e
l
a
k
ese
di
ments
i
s
di
st
i
nct an
di

np
l
aces mar
k
e
dby
sand and silt rich in organic remains: the freshwate
r
biv
a
lv
es
P
i
s
i
d
ium amnicu
m
(O.F. Mu
ll
er 1774) an
d
t
wo spec
i
es o
f
sna
il

s
,
Va
l
vata profun
da
(
C
l
ess
i
n
1887
)
an
d
Va
l
vata
d
e
p
ressa
(
P
f
e
iff
er 1828
)

,w
hi
c
h
p
oint to a rather shallow water u
pp
er littora
l
env
i
ronment (Han
g
et a
l
., 2001) at t
h
et
i
me o
f
t
rans
i
t
i
on
f
rom g
l

ac
i
o
l
acustr
i
ne to Ho
l
ocene
l
a
k
e
sedimentation. The ostracod fauna in the overla
y
in
g
l
a
k
e mar
l
sequence, part
i
cu
l
ar
ly
I
l

yocypris
b
ra
d
y
i
an
d
H
erpetocypr
i
s reptan
s
(N
ii
nemets, 1999),
i
n
di
cate
a
w
ater depth of around 4 m durin
g
the period (ca
.
1,000
y
rs) of lake marl accumulation. At the be
g

in
-
n
i
n
g
o
f
t
h
e succee
di
n
ggy
tt
j
a
d
epos
i
t
i
on t
h
e wate
r
l
evel of Lake Pei
p
si

p
ro
p
er was still so low that it was
isolated from the bod
y
of water in the southern part of
th
e
l
a
k
e
d
epress
i
on (Dav
yd
ova & K
i
mme
l
, 1991
;
H
ang & Miidel, 1999)
.
Mater
i
als and methods

The sites of buried coarse detritus
gy
tt
j
a (58
°
30
0
06
00
N; 27
°
23
0
21
00
E; Fi
g
. 1) reported in Han
g
et al.
(
2001) were revisi ted and five
p
arallel sediment
sequences were o
b
ta
i
ne

dby
cor
i
n
g
t
h
rou
gh
t
h
e
l
a
k
e
ice at a water depth of 7.30 m. A Russian type pea
t
corer with a 1 m lon
g
and
5
cm diameter chamber
w
as use
d
.T
h
e sam
pl

es were wra
pp
e
di
n
pl
ast
i
c
film
and placed in suitable lengths of a U-shaped PVC
t
rou
g
h for transport and stora
g
e.
C
o
l
our
d
eterm
i
nat
i
on o
f
t
h

ese
di
ment
f
o
ll
o
w
e
d
t
h
e
M
unsell soil colour chart (Munsell Color Company
,
1998) and the
p
H of fresh water-saturated sediments
w
as measured with an Evikon pH meter E
6
121.
T
h
e organ
i
c content as
l
oss-on-

i
gn
i
t
i
on (LOI) wa
s
estimated in
5
0 continuous 2 cm sub-sam
p
les fro
m
th
ese
di
ment sequence 8.20–9.20 m. T
h
e LOI wa
s
est
i
mate
df
rom
d
r
i
e
d

samp
l
es
b
y
i
nc
i
nerat
i
on at
5
0
0
°
C for 2 h
.
F
i
g
.
1
L
ocat
i
on o
f
t
h
ese

di
ment sequences
i
nvest
ig
ate
di
n
Lake Peipsi, eastern Estonia. Basal deposits accordin
g
to Han
g
eta.(00)
et al. (
2
00
1
)
14
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
1
2
3
Pollen samples were prepared followin

g
the stan-
d
ar
d
tec
h
n
i
que (Berg
l
un
d
&Ra
l
s
k
a-Jas
i
ew
i
czowa,
1
986) with additional flotation treatment of highl
y
m
inero
g
enic sample s with a heav
y

liquid (Cd
J
2
a
n
d
K
Jso
l
ut
i
on w
i
t
h
spec
ifi
c grav
i
ty 2.2 g c
m
-
3
)
. Nor-
m
ally, 500 land pollen grains were counted pe
r
sample and aquatics, spores and coenobia of the
g

reen a
lg
a
P
e
d
ia
s
tru
m
were
id
ent
ifi
e
d
.T
h
e percent
-
a
ge po
ll
en
di
agram was comp
il
e
d
us

i
n
g
T
i
l
ia-
Tili
a
*Graph software (Grimm, 1992).
Samp
l
es
f
or macro
f
oss
il
ana
ly
ses were enr
i
c
h
e
d
o
n
a
0.25 mm mesh sieve by washing with tap water

.
Id
ent
ifi
cat
i
on was per
f
orme
db
y Ms. S
i
r
j
eH
ii
eus
i
n
g
a
Nikon SMZ800 stereomicrosco
p
e at 10–
6
3
9
mag
-
n

ification, emplo
y
in
g
the ke
y
s of Katz et al. (1965,
1
977
)
an
d
Sc
h
oc
h
et a
l
.
(
1988
)
an
d
t
h
ere
f
erence
c

ollection of seeds and fruits in the Laborator
y
o
f
Geoarc
h
aeo
l
o
gy
an
d
Anc
i
ent Tec
h
no
l
o
gy
at t
he
I
nst
i
tute o
f
H
i
story o

f
t
h
eTa
lli
nn Un
i
vers
i
ty.
A
J
enaval microsco
p
e with 400
9
ma
g
nification was
u
se
d
to
id
ent
ify
p
l
ant t
i

ssues.
Se
di
ment su
b
-samp
li
ng an
d
s
lid
e preparat
i
on
f
o
r
d
iatom analyses followed the standard technique
outlined b
y
Battarbee (198
6
). Diatoms were counte
d
u
s
i
n
g

aZe
i
ss III RS m
i
croscope w
i
t
h
a10
0
9
P
l
an
-
a
po phase contrast obje ctive and 10
9
eye-pieces. At
l
east
5
00 diatom valves were counted
p
er sam
p
le.
Bro
k
en va

l
ves were counte
d
as a un
i
t
if
at
l
east two-
t
hirds had remained. Half
v
al
v
es
w
ere counted as a
h
a
lf b
ut sma
ll
er p
i
eces were not counte
d
(M
i
ett

i
nen,
2
002). Taxonomy an
d
group
i
ng o
fdi
atoms
b
y
b
iot
y
pe and pH and salinit
y
preferences followe
d
Krammer & Lan
g
e-Bertalot (198
6
, 1988, 1991a, b).
R
esu
l
t
s
S

ediment lithostratigraphy
T
h
e
l
ate
gl
ac
i
a
l
/Ho
l
ocene se
di
ment sequence ana
-
l
ysed consists of four lithostratigraphic layers. Late
W
eichselian till at the bottom of the lake de
p
ressio
n
is overlaid b
y
medium-
g
rained sand with a low
o

rganic matter content (Fig. 2, depth 9.20–9.06 m).
The sand is followed by a coarse detritus gyttja laye
r
(
9.06–8.33 m) in which the or
g
anic content increases
f
rom 5–10% in the lower part (9.06–8.90 m) to a
maximum of 2
5
–40% in the upper part (8.6
5–
8.40 m). The to
p
most 7 cm (8.40–8.33 m) of th
e
gytt
j
a
i
nterva
li
sc
h
aracter
i
se
db
y a rap

id d
ecrease
i
n
o
rganic content from 3
5
%to
5
%. This change marks
t
he transition from gyttja to the uppermost sediment
l
a
y
er, t
h
e
fi
ne-
g
ra
i
ne
dl
acustr
i
ne san
d
at a

d
ept
h
o
f
8.33–7.30 m (F
i
g. 2)
.
Fi
g.
2
Pollen percenta
g
e dia
g
ram with indication of the loca
l
p
ollen assemblage zones (LPAZ: PE-1–PE-3), relative propor-
gp, gpy
t
i
ons o
f
t
h
ema
i
n terrestr

i
a
lg
rou
p
s
,li
t
h
ostrat
ig
ra
phy
an
d
LO
I
o
f sediments
.
T
he black areas on the dia
g
ram show the actual
pollen in percentages, while the white areas show the
pg p
p
ercenta
g
es mu

l
t
ipli
e
d
10-
f
o
ld
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
1
5
1
23
T
he colour of the
gy
tt
j
ala
y
er chan
g
es from dark

reddish brown (Munsell colour designation: 5YR/3-2
)
i
n the lower part (9.0–8.6 m) into greenish blac
k
(Gle
y
1/2.
5
–1) in the upper portion (8.6–8.43 m), an
d
back to reddish brown (5YR/2.5–1) in the topmost
1
0 cm. The colour change is apparently due to
v
ariable oxidation of Fe-com
p
ounds in the sediments,
re
fl
ect
i
ng pre
d
om
i
nant
l
y
f

errous (F
e
2
+
),
i
.e. mor
e
re
d
uce
d
, compoun
d
s
i
nt
h
em
iddl
e part o
f
t
h
e gytt
j
a
l
ayer. T
h

epHo
f
t
h
e gytt
j
a
i
nterva
l
var
i
es
b
etwee
n
7.18 and 7.37 with the lowest value in the u
pp
er
p
ar
t
(at 8.5 m), where the or
g
anic content reaches it
s
m
ax
i
mum. T

h
e gytt
j
a
l
ayer conta
i
ns a v
i
s
ibl
e num
b
e
r
of
p
lant macrofossils. The first AMS radiocarbo
n
d
ates o
f
t
h
ese macro
f
oss
il
ss
h

ow t
h
at t
h
e
gy
tt
ja
d
eposition took place between 9.
6
and 9.1 ka
14
C
BP
.
Po
ll
e
n
data
T
he percentage pollen diagram was plotted, taking
the sum of arboreal
(
AP
)
and non-arboreal
(
NAP

)
po
ll
en as 100% (F
i
g. 2). T
h
ree
l
oca
l
po
ll
en assem
-
bl
age zones (LPAZ: PE-1, PE-2, PE-3) were
e
stablished from the most characteristic changes i
n
po
ll
en compos
i
t
i
on (F
ig
.2)
.

PE-1
(
9.20–8.75 m
)
: in this LPAZ the dominan
t
(26–28%) arboreal pollen taxon on average i
s
B
etul
a
,
whil
e
Pi
nu
s
h
as
l
ow re
l
at
i
ve va
l
ues (8–11%). T
h
e
o

n
l
y excep t
i
on to t
h
at ru
l
e
i
st
h
e
l
owermost samp
l
e
from the massive sand overlying the till, where these
taxa have values of 3
6
% and 19%, respectivel
y
. The
Pi
ce
a
,
U
l
mus, Cory

l
u
s
a
n
d
Al
nu
s
po
ll
en gra
i
ns
i
nt
h
e
samp
l
es are
b
e
li
eve
d
to represent re
d
epos
i

te
d
mate
-
rial
.
S
ali
x
pollen is present re
g
ularl
y
throu
g
hout the
w
h
o
l
e
di
a
g
ram at va
l
ues o
f
1–7%. T
h

e
ligh
t-
d
eman
d-
i
ng s
h
ru
bs
Jun
i
peru
s
an
d
Hippop
h
ae a
l
so occur
in
this LPAZ. The sum of
g
rass and herb pollen, mainl
y
a
ttr
ib

uta
bl
etoC
y
peraceae (24–28%) an
d
Poacea
e
(17–27%), accounts for up to 50–60% of the tota
l
p
ollen. In addition
,
A
rtemisia, Cheno
p
odiaceae
,
F
il-
ipendula
a
n
d
Th
alict
r
u
m are constantl
y

present in PE
-
1
an
d
t
h
e succee
di
ng LPAZ, PE-2 (F
i
g. 2). Aquat
i
cs
(
P
otamo
g
eton
,
Ny
mphae
a
,
Nu
p
ha
r
,
M

y
rioph
y
llum
)
a
re
p
resent in this LPAZ an
d
Pe
d
ia
s
trum
coe
n
ob
i
a
a
re a
b
un
d
ant
h
ere compare
d
to zones PE-2 an

d
PE-3
.
A
lso, spores o
f
L
y
copodium (not shown in Fig. 2),
E
q
uisetum
,
Pol
y
podiaceae
,
S
pha
g
num
a
n
d
S
ela
g
i
-
n

e
lla
w
ere recor
d
e
di
n PE-1.
PE-2
(
8.7
5
–8.30 m
)
: in this LPAZ, B
etula
p
olle
n
d
om
i
nates o
v
er
Pi
nu
s
,g
a

i
n
i
n
gi
ts max
i
mum va
l
ues
(6
0%) near the upper boundary of the zone
.
Ul
mu
s
,
Alnus
,
P
i
cea
a
n
d
C
or
y
lus are present as scattered
fi

n
d
s
.
Po
ll
en o
f
J
uniperu
s
i
s present (0.2%) on
ly i
n
th
e
l
ower part o
f
t
h
e zone. At t
h
e
l
ower
b
oun
d

ary o
f
t
he zone, Poaceae pollen accounts for up to 38% of
t
he total
p
ollen and decreases u
p
wards to 15–20%. A
similar upwards decrease (from 25% to 8%) wa
s
recor
d
e
di
nt
h
ea
b
un
d
ance o
f
Cyperaceae po
ll
en.
C
omparativel
y

hi
g
h values (10–1
5
%) of aquati
c
po
ll
en correspon
d
to t
h
e
l
eve
l
o
f
t
h
e
l
owest num
b
ers
of
P
e
d
iastrum

.
In t
h
e upper part o
f
t
h
e zone, at
8
.37 m, there is a si
g
nificant increase (12%) in
M
yriop
h
y
ll
um
.
PE-3 (8.30–8.20 m): t
h
e uppermost po
ll
en zone,
PE-3, in the se
q
uence is established on the basis of
t
he sam
p

les in which the concentration of
p
ollen fro
m
b
roa
d
-
l
eave
d
trees (Quercetum m
i
xtum) an
d
C
ory
l
u
s
is considerably higher than in PE-1 and PE-2 (3.3%
a
nd 2.2%, respectivel
y
). In this LPAZ the amount of
P
inu
s
pollen rises rapidl
y

to 4
6
% and the proportion
o
f
Al
nu
s
r
eaches 5%. After its peak in LPAZ PE-2
,
th
e amount o
f
Betu
l
a po
ll
en
d
ecreases to 37%. T
h
e
proportion of herb pollen is at its lowest value (9.
5
%
)
i
nt
h

ew
h
o
l
e
di
a
g
ram
h
ere, w
hil
e spores o
f
Po
ly
po-
di
aceae are more
f
requent (8%) t
h
an
i
n PE-2
.
C
oeno
bi
ao

f
P
e
d
iastrum sim
pl
ex an
d
P.
k
avrais
ky
w
ere identified in this zone. At the boundar
y
between
PE-2 an
d
PE-
3
t
h
ere
i
s a mar
k
e
dd
ecrease
i

nt
he
quant
i
ty o
f
aquat
i
cpo
ll
en
.
P
l
ant macro
f
oss
ils
M
acrosco
p
ic remains of 1
5p
lant taxa were recorded
f
rom t
h
e coarse
d
etr

i
tus
gy
tt
j
a sequence. T
h
e
high
es
t
concentration of macrofossils was in the lower part of
t
he section studied (8.48–8.74 m). Submerged aquat
-
ics (ei
g
ht taxa) and littoral heloph
y
tes and wetland
pl
ants (
fi
ve taxa) are c
h
aracter
i
st
i
co

f
t
h
e assem
bl
age.
Table 1 gives a detailed overview of the distribution
an
dg
roup
i
n
g
o
f
t
h
ep
l
ant macro
f
oss
il
s
id
ent
ifi
e
d.
Diatom assembla

g
e
s
About
6
7 diatom taxa
w
ere identified from th
e
s
ediment sequence anal
y
sed. Genera with the
g
reates
t
1
6
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
1
2
3
T
able

1
P
l
ant macro
f
oss
il
s recor
d
e
df
rom t
h
e coarse
d
etr
i
tus gytt
j
a
i
nterva
l
o
f
t
h
ese
di
ment core

i
nvest
i
gate
df
rom La
k
ePe
i
ps
i
G
rou
p
s Taxa Remains De
p
th (cm
)
S
u
m
8
17–819 822–824 826–829 829–831 833–83
5
848–8
5
18
5
1–8
5

3 860–863 863–86
5
871–874 880–882 888–890
A
q
uat
i
c
N
u
ph
ar
l
ute
a
(
L.
)
Sm. See
d
11
2
P
otamo
g
eton natan
s
L
.
Fru

i
t
55
P
otamogeton sp. Fru
i
t
22
P
otamo
g
eto
n
s
p
. Stem f 1 1 1 1 4
C
har
a
s
p. Oo
g
one 3 5 2 1
0
Myriop
h
y
ll
um s
p

. See
d3
3
M
y
riop
hyll
um s
p
. Lea
ff
1111 4
R
anuncu
l
us su
bg
Bat
r
ac
h
ium
F
ru
i
t21
3
Al
isma
p

lantago-aquatic
a
L
.
S
ee
d
11
Ny
mp
h
aea a
lba
L. See
d1
1
Sum of remains 3 2 1 8 12 3 4 2 3
5
S
um of taxa 1 2 1
5
42
3
2
P
lants o
f
w
et
l

an
d
san
d
s
hores
E
l
eoc
h
aris s
p
. Fru
i
t
11
Phra
g
mites australi
s
(Cav) Tr
i
n.ex Steu
d.
S
tem f *
Menyanthes tri
f
oliata
L

.
S
eed
1
1
Sc
h
oeno
pl
ectus
l
acustri
s
(L.) Palla
F
ruit
5
14 6 2
5
C
are
x
s
pp
. Fru
i
t
22
Sum of remains 1 5 17 6 29
Sum o

f
taxa 1 1 1 3 1
W
oo
dl
an
d
an
d
sc
r
ubla
n
d
Al
nu
s
sp
. Fru
it
11
Betula pubescen
s
E
hrh. cs
/
fruit
11 2
S
um o

f
rema
i
n
s
2
1
3
S
um of tax
a
21
M
osses a
n
d other
plant remain
s
*****
Fra
g
ments o
f
tree
b
ar
k
**
*
Stems and leaves * *

T
otal su
m
of
r
e
m
ai
n
s
1
3
211
33
1
3
11 2
6
7
T
otal su
m
of ta
x
a
1121 61
9
2
52
cs, cat

ki
n sca
l
e;
f
,
f
ragment; *, spec
i
es not
id
ent
ifi
e
d
L
ocation of the site indicated in Fi
g
.1
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
1
7
1
23

n
umber of taxa
w
ere
:
N
avicul
a
(13)
, Epithemia (
6
),
Cym
b
e
ll
a
(
5
)
and
N
it
z
sc
h
ia
(
5). The most frequent
d

iatoms wer
e
Na
v
icula scutelloides W. Smith
(
reach
-
i
n
g
a share of 71% at 8.27 m)
,
E
lle
r
beckia a
r
e
n
a
r
ia
(Moore) Craw
f
or
d
(32% at 8.20 m),
G
yrosigma

a
ttenuatu
m
(Ku
tzing) Rabenhorst (24% at 8.
5
3m)
,
Ep
ithemia adnat
a
(Ku
tzing) Bre
´
bisson
(
1
5
%at
8
.39 m) an
d
S
yne
d
ra u
l
na
(
N

i
tzsc
h
)E
h
ren
b
er
g
(
11% at 8.60 m). The dominant diatom species are
presented in Fig. 3. Benthic and epiphytic specie
s
d
om
i
nate t
h
rou
gh
out t
h
ese
di
ment sequence. P
l
an
k
-
ton

i
c spec
i
es were
id
ent
ifi
e
di
n
l
ow quant
i
t
i
es
i
nt
h
e
l
ower part of sequence at 9.00 m and 8.8
5m
(
reachin
g
a maximum share of 5%). The diato
m
fl
ora

i
s
d
om
i
nate
db
y
f
res
h
water
f
orms. A
lk
a
li
p
hil
ou
s
d
iatoms that thrive in high pH waters dominate
,
reachin
g
up to 82% at 8.25 m. On the basis of the
di
atom compos
i

t
i
on an
d
success
i
on
i
nt
h
ese
di
ment
sequence, t
h
ree
l
oca
ldi
atom zones (LDZ) were
d
istin
g
uished (Fi
g
. 3).
L
DZ-1 (9.00–8.37 m):
i
nt

hi
s zone, s
h
a
ll
ow water
b
ent
hi
can
d
ep
i
p
h
yt
i
c spec
i
es
d
om
i
nate, nota
bl
yt
h
e
be
n

t
hi
c
E
lle
r
beckia a
r
e
n
a
r
ia
(u
p
to 30%) in the lower
p
art (9.00–8.65 m), while the benthic
G
yrosigm
a
attenuatum
a
nd epiphyti
c
Ep
ithemia adnata
a
r
e

m
o
r
e
abundant (24% and 15%, respectivel
y
) in the upper
part (8.65–8.37 m). The epiphyti
c
Syne
d
ra u
l
n
a
an
d
t
h
ebe
n
t
hi
c
Navicula oblon
ga
Ku
t
zing are presen
t

throu
g
hout LDZ-1 in amounts between 5% and 12%
.
Greater quant
i
t
i
es o
f
t
h
e
b
ent
hi
c/pseu
d
op
l
an
k
ton
ic
C
ampy
l
o
d
iscus

h
i
b
ernicu
s
E
h
ren
b
erg (up to 10%)
w
ere observed onl
y
in the lowermost (9.00– 8.90 m)
part o
f
LDZ-1
.
L
DZ-2 (8.37–8.28 m): re
l
at
i
ve
l
y
f
ew
di
atom

f
rus
-
tules (e.
g.
C
occoneis
p
lacentul
a
Ehrenber
g,
E
pit
h
emia a
d
nata, Fragi
l
aria pinnat
a
E
h
ren
b
er
g
)
w
ere

f
oun
di
nt
hi
s
i
nterva
l
, pro
b
a
bl
y
i
n
di
cat
i
ng t
h
e
emer
g
ence of the sediments above the water level
.
L
DZ-3 (8.28–8.20 m): the lower
p
ortion of this

z
one (8.28–8.23 m) compr
i
ses ma
i
n
ly b
ent
hic
N
a
v
icula
t
axa (especially
N
. scutelloide
s
—u
p
t
o
7
1%), as well as epiph
y
tic diatom species from the
genera
E
pit
h

emia
a
n
d
C
occonei
s
(F
ig
. 3). In t
h
e
upper part of LDZ-3 the benthic
Elle
r
beckia a
r
e
n
a
-
r
ia
a
nd the epiph
y
ti
c
E
p

ithemia adnat
a
accou
n
t
f
o
r
up to 32% and 15%, respectivel
y
. The amount of N
.
scutelloide
s
decreases in the upper layers of the zone
t
o 1–2%.
Fi
g. 3 Dia
g
ram displa
y
in
g
succession of selected diatom tax
a
a
nd diatom assemblage zones (DAZ). Grouping of tax
a
gy, pp

a
ccor
di
n
g
to sa
li
n
i
t
y, h
a
bi
tat an
dp
H
p
re
f
erence. So
lid
curv
e
represents the actual percenta
g
e, while empt
y
curves show th
e
percentage values multiplied by 1

0
18
Hy
drobiolo
g
ia (2008)
5
99:13–2
1
1
2
3