Late Glacial and Holocene Ostracoda of the Gulf of Gdańsk, the Baltic Sea, Poland

© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim 1434-2944/12/408-0301

Internat. Rev. Hydrobiol. 97 2012 4 301–313

DOI: 10.1002/iroh.201211493

JARMILA KRZYMINSKA1 and TADEUSZ NAMIOTKO*, 2

1Polish Geological Institute-National Research Institute, Branch of Marine Geology, Kościerska 5, 80-328 Gdańsk, Poland; e-mail: [email protected]

2University of Gdańsk, Department of Genetics, Laboratory of Limnozoology, Kładki 24, 80-822 Gdańsk, Poland; e-mail: [email protected]

Research Paper

Late Glacial and Holocene Ostracoda of the Gulf of Gdańsk, the Baltic Sea, Poland

key words: Palaeoenvironmental reconstruction, stratigraphical distribution, lacustrine conditions, Atlantic marine transgression, brackish-water species

Abstract

To trace environmental changes in water hydrology and salinity in the Late Glacial to Holocene of the Gulf of Gdańsk, a south-eastern bay of the Baltic Sea within the maritime zone of Poland, the distribution of ostracod valves was studied in 20 sediment cores collected from both the shallow- and deep-water zones (depth 10.9–67.5 m). The studied sediment sequences yielded ca. 3000 valves of 21 ostracod species, of which only five are known to live today in the Gulf, which has a present maximum depth of 118 m and water salinity up to 7–8‰. The majority of the studied sediment layers that contained ostracod valves corresponded to the period of the Late Glacial to Mid-Holocene and was dominated by non-marine species, of which the most common were Candona neglecta (present in 17 cores), Cytherissa lacustris (15 cores) and Candona candida (14 cores). By clustering classification five major ostracod assemblage types were recognised in the studied cores. Initial assemblage types dominated mostly by inhabitants of the profundal/sub-littoral zones of modern oligo-mesotrophic lakes (C. lacustris and C. neglecta) in some sediment sequences were replaced in stratigraphical order by the assemblages dominated by brackish-water species (Cyprideis torosa or Cytheromorpha fuscata). The structure and species composition of the distinguished ostracod assemblage types as well as their suc-cessional transitions indicate that the studied sediments were deposited initially in the Late Glacial in freshwater lacustrine conditions, and subsequently, during the Holocene marine transgression, covered by marine sands. The present results confirm and consolidate inferences based on previously published data on ostracods from the western part of the Gulf of Gdańsk as well as on other biotic (molluscs, diatoms) and abiotic (seismoacoustic) indices from this area.

1. Introduction

In the Polish maritime zones of the Baltic Sea thus far a total of 49 (14 marine and 35 fresh- and/or brackishwater) living ostracod species have been recorded (NAMIOTKO, in press), which constitutes 38% of the total number of extant ostracod species known from the whole Baltic (FRENZEL et al., 2010). Quaternary ostracod faunas of the Polish coastal marine zone have been poorly investigated. Until the end of the last century overall only 19 spe-cies have been reported from boring holes at modern coastal inland sites (BRODNIEWICZ,

* Corresponding author

302 J. KRZYMINSKA and T. NAMIOTKO

© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim www.revhydro.com

1972; 1979; BRODNIEWICZ and ROSA, 1967; KOPCZYŃSKA-LAMPARSKA et al., 1984) and from cores taken from the bottom of the Vistula Lagoon (JANISZEWSKA-PACTWA, 1973). Recently, ostracod studies have been undertaken also in the open sea zone along the southern Baltic shore (KRZYMIŃSKA and PRZEZDZIECKI, 2001; KRZYMIŃSKA et al., 2005; KRZYMIŃSKA and PRZEZDZIECKI, 2010), bringing the total number of Quaternary ostracod species recorded in the Polish maritime zones of the Baltic Sea to 29, of which 20 have been reported from the Late Glacial/Holocene freshwater and marine deposits of the Gulf of Gdańsk, a south-eastern bay of the Baltic.

Although the primary evolution of the Baltic Sea from the time of the last Scandinavian ice-sheet decay is well established, some details on the changes and the environmental impact on the south and south-eastern coastal zone of the modern Baltic during its subse-quent developmental stages in Late Glacial and Holocene still remain unclear and are open to debate (e.g., ŪSAITYTĖ, 2000; LAMPE, 2005; VIEHBERG et al., 2008). The complex and dynamic hydrological history of the Baltic started at around 14 ka years before the present (yr BP) when the first freshwater bodies of various size were formed at the front of the retreating ice-sheet and later grew to the Baltic Ice Lake, a large freshwater lake fed by melt waters and rivers, which reached its greatest extent 10.5–10.3 ka yr BP (MOJSKI, 2000; LAMPE, 2005). One of the most dramatic environmental changes in the Holocene history of the Baltic is the Littorina transgression, when owing to the eustatic sea-level rise marine waters entered the Baltic Basin and caused the major hydrological shift from the freshwater system into the brackish-marine Littorina Sea (RÖSSLER et al., 2011), the maximum extent of which is dated in the Gulf of Gdańsk at 6.3–6.4 ka yr BP (MOJSKI, 2000). Such a fun-damental transformation had a significant impact on the faunal change, what is reflected in almost all developmental stages of the Baltic Sea named after characteristic key molluscan species, clear markers of changing water salinity. However, little attention has been paid to the use of ostracods in tracing environmental change during the different Baltic stages (see review in VIEHBERG et al., 2008 and FRENZEL et al., 2010), despite the fact that ostracods from brackish waters have been proven to be valuable tools in palaeoenvironmental recon-structions (FRENZEL and BOOMER, 2005). Late Glacial and Holocene ostracod palaeoassem-blages are known mostly from the south-western part of the Baltic Basin (Mecklenburg-Bay, Arkona Basin, Pomeranian Bay and southern Sweden) and provide evidence mainly for the Baltic Ice Lake phase (reviewed in VIEHBERG et al., 2008), but incomplete records exist for the south-eastern part of the Baltic and documenting the rapid transition from freshwater into marine conditions (with the exception of KRZYMIŃSKA et al., 2005; KRZYMIŃSKA and PRZEZDZIECKI, 2010).

The present contribution documents stratigraphical distribution of ostracod valves in Late Glacial to Mid-Holocene intervals of 20 cores recovered from the bottom of the Gulf of Gdańsk to trace the environmental change in water hydrology and salinity of the south-eastern bay of the Baltic Proper.

2. Material and Methods

The distribution of ostracod valves was studied in 20 sediment cores collected from the bottom of the Gulf of Gdańsk between ca. 54°23ʹ–54°35ʹ N and 18°38ʹ–19°26ʹ E (Fig. 1). The Gulf of Gdańsk is a south-eastern bay of the Baltic Sea with the present-day maximum depth of 118 m and water salinity up to 7–8‰. The shallow-water zone of the sandy bottom slopes gently to a depth of 35–40 m and is separated by the slope from the deep-water zone of the muddy bottom which begins at a depth of ca. 50–60 m and slopes gently further towards the Gdańsk Deep (MOJSKI et al., 1995; KRZYMIŃSKA and PRZEZDZIECKI, 2010).

Out of 20 cores, five (Cores 1–5) were recovered from the slope and deep-water zone (depths 44.5–67.5) of the western part of the Gulf, other five (Cores 6–10) from the shallow-water zone (depths 10.9–29.8 m) of the western part of the Gulf, seven cores (11–17) were taken from the eastern part of the

Late Glacial-Holocene Ostracoda of the Gulf of Gdańsk, Baltic, Poland 303


Gulf (depths 36.0–67.5 m), while the sites of the collection of the remaining three cores (Cores 18–20) were situated in the central part of the Gulf at the depths of 18.0–33.0 m along the transect parallel to the foreland of the Vistula River mouth (Fig. 1). Besides new data on 14 cores, the material from six other cores (Cores 6 and 8–10: KRZYMIŃSKA and PRZEZDZIECKI, 2010 and Cores 4–5: KRZYMIŃSKA et al., 2005) was re-examined and included in the palaeoenvironmental analysis. All the cores were collected with a vibrocorer in 1985–2008 during the various geological works (mapping, geotechnical investigation, etc.) of the Marine Geology Branch of the Polish Geological Institute-National Research Institute.

Ostracods were examined following standard methods (GRIFFITHS and HOLMES, 2000) throughout the recovered profiles chiefly at 5–10 cm intervals. Each sediment sample of a 200 cm3 volume was disaggregated with H2O2, sieved at 100 μm with water and dried at room temperature. Ostracod valves were handpicked from the remaining sediment residue, counted and identified under a stereomicro-scope at a magnification up to 100 ×. Taxonomic references were SYWULA (1974), SYWULA and PIE-TRZENIUK (1994), GRIFFITHS and HOLMES (2000), MEISCH (2000) and FRENZEL et al. (2010). Scanning electron micrographs (SEM) were taken to illustrate the recovered ostracod valves. The study material is housed in the Marine Geology Branch of the Polish Geological Institute-National Research Institute in Gdańsk.

Ostracod distribution in the studied sediment cores was presented on stratigraphical diagrams plotting categorised abundances (1 = 1 valve, 2 = 2–10 valves, 3 = 11–100 valves and 4 = 101–1000 valves per 200 cm3 of fresh sediment) vs. depth using C2 v. 1.5 programme (JUGGINS, 2007). The ostracod samples from particular sediment layers of the studied sequences were classified by an Unweighted Pair Group Mean Average (UPGMA) hierarchical clustering based on species categorised abundances and Bray-Curtis similarity coefficient using PRIMER ver. 6.1.10 software (CLARKE and GORLEY, 2006).

Figure 1. Bathymetric map of the Gdańsk Bay with sites from which cores were recovered for the present study.



3. Results

The studied core sediment sequences yielded in total almost 3000 valves of 21 ostracod species (Table 1, Fig. 2) recovered from 105 sediment layers corresponding to the period of the Late Glacial to Mid-Holocene. Most of the identified species are typical non-marine forms, of which the most common were: Cytherissa lacustris (present in 77% of the stud-ied sediment layer samples of the 15 cores), Candona neglecta (76% of the samples in 17 cores), Candona candida (21% of the samples in 14 cores), Limnocythere inopinata (20% of the samples in 8 cores) and Limnocytherina sanctipatricii (12% of the samples in 7 cores).

Stratigraphical distributions of ostracods through the recovered cores are presented in Figs. 3–5, whereas the results of the cluster analysis of ostracod assemblages from particular sediment layers are in Fig. 6.

By clustering classification five major clusters were recognised referred here to as the palaeoassemblage types (Fig. 6):

1) a palaeoassemblage type A1 dominated by Cytherissa lacustris accompanied by Can-dona neglecta (and occasionally by Limnocythere inopinata, Candona candida, Limnocy-therina sanctipatricii, Fabaeformiscandona levanderi, F. protzi, Herpetocypris reptans, Ilyo-cypris spp., Cyclocypris spp. and Cypridopsis vidua), the most common palaeoassemblage type in the studied material, represented by 78% of the studied sediment samples bearing ostracod valves;

2) a palaeoassemblage type A2 clearly dominated by Candona neglecta (with occasion-ally co-occurring valves of the genus Fabaeformiscandona), the second most common pal-aeoassemblage type, represented by 11% of the studied sediment samples with ostracods;

3) a palaeoassemblage type B dominated by Candona candida accompanied by C. neglec-ta (and accidental valves of Fabaeformiscandona sp., H. reptans and C. vidua), found only in three samples;

4) a palaeoassemblage type C, the most taxonomically diverse, characterised principally by Darwinula stevensoni, Pseudocandona compressa and C. neglecta which were accom-panied by seven other species with lower abundances, found only in two studied samples;

5) a palaeoassemblage type D, clearly dominated by Cyprideis torosa with occasion-ally co-occurring P. compressa, represented by 4% of the studied sediment samples bearing ostracod valves. Ecologically similar to this palaeoassemblage type was a monospecific assemblage of Cytheromorpha fuscata found in one sample.

In the deep-water zone (depth > 40 m) of the western part of the Gulf of Gdańsk (Fig. 1), silty sand and dark grey sandy mud with detritus from the Core 3 (lower section radiocarbon dated at 12,200 ± 240 yr BP, UŚCINOWICZ and ZACHOWICZ, 1994) yielded the C. lacustris-C. neglecta palaeoassemblage A1 (Figs. 3 and 6). The same palaeoassemblage type, which was replaced in the stratigraphical order by the C. neglecta palaeoassemblage A2, was found also in three other cores from this part of the Gulf: in the Core 2 (the lower section paly-nologically dated at the Preboreal and Boreal, UŚCINOWICZ and ZACHOWICZ, 1994), in the Core 4, where calcareous varve clayey-sandy sediments of the lower section were radiocar-bon dated at 13,740 ± 70 yr BP (KRZYMIŃSKA et al., 2005), and in the Core 5 with sandy muds and muddy sands (Figs. 3 and 6). In the Core 1 from this part of the Gulf only valves of C. neglecta were found (Fig. 3).

The palaeoassemblage A1 prevailed also in the sediment samples of the cores from the eastern part of the Gulf (Fig. 1). In sandy mud and brown-grey silty sand of the Core 13 (lower section radiocarbon dated at 10,650 ± 160 yr BP, UŚCINOWICZ and ZACHOWICZ, 1994) besides the dominant Cytherissa lacustris accompanied by Candona neglecta, three other lacustrine ostracod species were found: Limnocytherina sanctipatricii, Candona candida and Ilyocypris decipiens (Fig. 5). Similar palaeoassemblages were recorded in the Core 11 (Fig. 3), Core 12 (Fig. 5), Core 14 (Fig. 4) and Core 17 (Fig. 5), the lower section of which



Tabl

e 1.

D

istri

butio

n of

ost

raco

d sp

ecie

s in

the

stud

ied

sedi

men

t cor

es. D

epth

indi

cate

s the

bot

tom

dep

th (i

n m

) bel

ow th

e se

a le

vel f

rom

w

hich

the

core

s w

ere

reco

vere

d. C

ore

leng

th in

dica

tes

the

tota

l cor

e le

ngth

(in

cm).

Ds

– D

arw

inul

a st

even

soni

(BR

AD

Y a

nd R

OB

ERTS

ON

, 18

70);

Cc

– C

ando

na c

andi

da (O

. F. M

ÜLL

ER, 1

776)

; Cn

– C

ando

na n

egle

cta

SAR

S, 1

887;

Cw

– C

ando

na w

eltn

eri H

AR

TWIG

, 189

9; F

a –

Faba

efor

mis

cand

ona

cf. a

lexa

ndri

(SY

WU

LA, 1

981)

; Fl –

Fab

aefo

rmis

cand

ona

leva

nder

i (H

IRSC

HM

AN

N, 1

912)

; Fp

– Fa

baef

orm

isca

ndon

a pr

otzi

(HA

RTW

IG, 1

898)

; Pc

– Ps

eudo

cand

ona

com

pres

sa (K

OC

H, 1

838)

; Cl –

Cyc

locy

pris

laev

is (O

. F. M

ÜLL

ER, 1

776)

; Co

– C

yclo

cypr

is

ovum

(J U

RIN

E, 1

820)

; Id

– Ily

ocyp

ris

deci

pien

s M

ASI

, 190

5; I

l – I

lyoc

ypri

s cf

. lac

ustr

is K

AU

FMA

NN

, 190

0; H

r –

Her

peto

cypr

is r

epta

ns

(BA

IRD

, 183

5); S

t – S

cotti

a cf

. tum

ida

(JO

NES

, 185

0); C

v –

Cyp

rido

psis

vid

ua (O

. F. M

ÜLL

ER, 1

776)

; Li –

Lim

nocy

ther

e in

opin

ata

(BA

IRD

, 18

43);

Ls –

Lim

nocy

ther

ina

sanc

tipat

rici

i (B

RA

DY

and

RO

BER

TSO

N, 1

869)

; Mc

– M

etac

ypri

s cor

data

BR

AD

Y a

nd R

OB

ERTS

ON

, 187

0; C

yth

– C

y the

riss

a la

cust

ris

(SA

RS,

186

3); C

t – C

ypri

deis

toro

sa (

JON

ES, 1

850)

; Cf

– C

ythe

rom

orph

a fu

scat

a (B

RA

DY,

186

9).

Cor

e N

o.1

23

45

67

89

1011

1213

1415

1617

1819

20

Fiel

d co

deR

162Z

G13

81Z

G54

6/20

013/

2001

4/20

01R

20W

B1

WB

6W

B7

R3/

82R

3a/8

2EL

1R

127

R11

94Z

G15

24Z

G14

8R

6/82

R5/

82R

4/82

Dep

th44

.561

.067

.562

.054

.529

.813

.010

.912

.112

.638

.046

.053

.448

.548

.750

.067

.530

.018

.033

.0

Cor

e le

ngth

260

400

500

345

390

375

300

357

382

356

360

500

700

250

190

580

500

480

300

180

Ds

XC

cX

XX

XX

XX

XX

XX

XX

XC

nX

XX

XX

XX

XX

XX

XX

XX

XX

Cw

XFa

XFl

XX

XFp

XPc

XX

XC

lX

Co

XId

XX

XX

IlX

XX

Hr

XX

XSt

XC

vX

XLi

XX

XX

XX

XX

LsX

XX

XX

XX

Mc

XC

yth

XX

XX

XX

XX

XX

XX

XX

XC

tX

XX

Cf

X



Figure 2. Scanning electron micrographs of the studied species: 1 – Fabaeformiscandona levanderi female right valve (RV): 1a – outer view (ov), 1b – inner view (iv); 2 – Candona candida female left valve (LV): 2a – ov, 2b – iv; 3 – Candona neglecta female: 3a – LV ov, 3b – RV iv; 4 – Pseudocan-dona compressa adult (ad.) RV: 4a – ov, 4b – iv; 5 – Fabaeformiscandona protzi female RV: 5a – ov, 5b – iv; 6 – Candona weltneri ad. LV: 6a – ov, 6b – iv; 7 – Cyclocypris ovum ad. LV: 7a – ov, 7b – iv; 8 – Cytherissa lacustris female RV ov; 9 – Darwinula stevensoni female LV ov; 10 – Herpetocypris reptans female RV: 10a – ov, 10b – iv; 11 – Ilyocypris decipiens ad. RV: 11a – ov, 11b – iv; 12 – Lim-nocytherina sanctipatricii female LV: 12a – ov, 12b – in; 13 – Metacypris cordata female LV: 13a – ov, 13b – iv; 14 – Scottia cf. tumida ad.: 14a – LV ov, 14b – RV iv; 15 – Cyprideis torosa male LV: 15a –

ov, 15b – iv; 16 – Cytheromorpha fuscata female LV: 16a – ov, 16b – iv.



Figure 3. Stratigraphical distribution and categorised abundances (1 = 1 valve, 2 = 2–10 valves, 3 = 11–100 valves, 4 = 101–1000 valves in 200 cm3 of sediment) of ostracods through the Cores 1–7 and 11. Species codes as in Table 1. Vertical axes represent the core length in cm. Lithology: 1 – sandy grav-el, 2 – coarse sand, 3 – medium- and fine-grained sand, 4 – fine-grained sand, 5 – silty sand, 6 – muddy sand, 7 – silt, 8 – silty sand, 9 – silty clay, 10 – clay, 11 – animal remains, 12 – plant macroremains.



was palynologically dated at the Preboreal-Boreal (UŚCINOWICZ and ZACHOWICZ, 1994). In the Core 16 from this part of the Gulf the palaeoassemblage type B (dominated by Candona candida accompanied by C. neglecta and some littoral dwelling species) was found (Figs. 5 and 6), whereas in the Core 15 the palaeoassemblage A1 was replaced in the uppermost layer by the monospecific asseblage of Cytheromorpha fuscata (Figs. 4 and 6).

Figure 4. Stratigraphical distribution and categorised abundances (1 = 1 valve, 2 = 2–10 valves, 3 = 11–100 valves, 4 = 101–1000 valves in 200 cm3 of sediment) of ostracods through the Cores 8–10 and 14–15. Species codes as in Table 1. Vertical axes represent the core length in cm. Lithology as in

Fig. 3.



Figure 5. Stratigraphical distribution and categorised abundances (1 = 1 valve, 2 = 2–10 valves, 3 = 11–100 valves, 4 = 101–1000 valves in 200 cm3 of sediment) of ostracods through the Cores 12–13 and 16–20. Species codes as in Table 1. Vertical axes represent the core length in cm. Lithology as in

Fig. 3.



Figu

re 6

. R

esul

ts o

f the

clu

ster

ana

lysi

s (U

PGM

A c

lass

ifica

tion)

of o

stra

cod

asse

mbl

ages

from

par

ticul

ar s

edim

ent l

ayer

s of

the

stud

ied

core

s in

dica

ting

the

five

maj

or a

ssem

blag

e ty

pes

(A1,

A2,

B, C

and

D)

with

thei

r ke

y sp

ecie

s an

d th

e si

mpl

ified

mos

t com

mon

suc

cess

iona

l cha

nges

(da

shed

arr

ows)

. Th

e si

ze o

f th

e ill

ustra

ted

ostra

cod

valv

es i

ndic

ates

in

sem

i-qua

ntita

tive

way

the

rel

ativ

e m

ean

prop

ortio

n of

the

key

spe

cies

. Sed

imen

t sa

mpl

e co

de:

15(0

.30–

0.60

) = se

dim

ent l

ayer

0.3

0–0.

60 c

m o

f th

e C

ore

15.



All samples of the Cores 8 and 9, recovered from the shallow-water zone of the western part of the Gulf of Gdańsk (Fig. 1), represented the palaeoassemblage A1, noticeably domi-nated by Cytherissa lacustris accompanied by Candona neglecta (Figs. 4 and 6), and were similar to most of the samples of the above mentioned cores from the deep-water zone of the western and eastern part of the Gulf. In the Core 6 ostracods were preserved only in clay and lacustrine gyttja, radiocarbon dated at 12200 ± 60 yr BP (KRZYMIŃSKA et al., 2005), and in clayey mud with algae, dated by 14C at 9510 ± 45 yr BP (KRZYMIŃSKA et al., 2005). The sediment sample layers of this core represented the palaeoassemblages A1, A2 and B (Figs. 3 and 6). In the Core 7 there were only two species recorded Candona neglecta and C. candida (Fig. 3). In silty sands of the Core 10 taken from the shallow-water zone of the western part of the Gulf (the 1.15–1.20 cm layer radiocarbon dated at 6720 ± 130 yr BP: KRZYMIŃSKA and PRZEZDZIECKI, 2010) the palaeoassemblage type C (characterised by lacustrine littoral species) and D (C. torosa dominated) were recorded (Figs. 4 and 6), indicating transitions from the brackish to fresh and again to brackish conditions.

Finally, ostracod palaeoassemblages of the sediment layers from the cores recovered from the central part of the Gulf (Fig. 1) were classified as representing either the C. lacustris-C. neglecta palaeoassemblage type A1 (Core 19, Fig. 5), the C. torosa palaeoassemblage type D (Core 20, Fig. 5) or transitions from the A1 to D (Core 18, Figs. 5 and 6).

4. Discussion

Most of the species identified in the studied cores are typical non-marine forms (Table 1, Fig. 2), known mainly from lacustrine habitats in both modern Europe (MEISCH, 2000) and European Quaternary sediments (GRIFFITHS, 1995), as well as from the Baltic Sea (FRENZEL et al., 2010). Environmental requirements of the five most common species (Cytherissa lacustris, Candona neglecta, Candona candida, Limnocythere inopinata and Limnocytherina sanctipatricii) reflect ecological conditions of the profundal to sublittoral bottom zones of slightly to moderately eutrophic recent European postglacial lakes (e.g., DANIELOPOL et al., 1990; NAMIOTKO, 1995; 1998; NAMIOTKO et al., 2012). Especially the common and abundant occurrence of Cytherissa lacustris, which is a polyoxyphilic, inbenthic ostracod that avoids sulphidic and organically enriched sediments (DANIELOPOL et al., 1990; GEIGER, 1993), indi-cates relatively oligotrophic and cold conditions.

Changes in the stratigraphical distributions of the distinguished ostracod assemblage types through the recovered cores, coupled with the data on lithology and on modern ostracod aut- and synecology, allowed interpreting the environmental changes in the Gulf of Gdańsk during the Late Glacial to Mid-Holocene (Fig. 6). In the studied sediment sequences of the Late Glacial to Early Holocene, dated at 12200 to 9220 yr BP (UŚCINOWICZ and ZACHOWICZ, 1994) and at 13740–9510 yr BP (KRZYMIŃSKA et al., 2005), the initial palaeoassemblages characterised by the dominance of Cytherissa lacustris and Candona neglecta accompanied by other typical lacustrine species (the palaeoassemblage types A1 and A2 in Fig. 6) were frequently recorded in most of the studied sediment profiles evidencing common occurrence of cold, oligo-mesotrophic and presumably mainly shallow lakes in the whole area of the Gulf of Gdańsk at that time. Only a few sediment samples yielded ostracod assemblages typical of the littoral lacustrine conditions of higher trophy (characterised by rich vegetation, muddy bottom, enhanced sedimentation and high detritus content) with such key species as Darwinula stevensoni, Pseudocandona compressa, Limnocythere inopinata, Herpetocypris reptans and Cypridopsis vidua (see the palaeoassemblage types B and C in Fig. 6). Such ancient lake sediments resting below more recently deposited marine sand were already documented in the western shallow-water zone of the Gulf by high-resolution seismoacous-tic survey supported by the ostracod based study by KRZYMIŃSKA and PRZEZDZIECKI (2010) as well as in the Pomeranian Bay, a south-western bay of the Baltic Sea, within both the



Polish (KRZYMIŃSKA and PRZEZDZIECKI, 2001) and German (VIEHBERG et al., 2008) part. Numerous freshwater bodies being a part of a system of periglacial lakes formed at that time in depressions of various kinds on a relatively low and flat terrain relieved of its ice load were also recorded by regular geological survey of the seabed in the area of the Gulf of Gdańsk (see MOJSKI, 2000 and UŚCINOWICZ, 2006 for details on evolution of the southern Baltic coastal zone).

The lacustrine ostracod palaeoassemblages were replaced in stratigraphical order by the palaeoassemblages dominated by the brackish-water species Cyprideis torosa or Cythero-morpha fuscata (see Fig. 6) during the Littorina Sea transgression in the Atlantic period dated in the Gulf of Gdańsk at about 8750 yr BP (UŚCINOWICZ and ZACHOWICZ, 1994) and 6670 yr BP (KRZYMIŃSKA and PRZEZDZIECKI, 2010).

To conclude, the structure and species composition of the ostracod palaeoassemblages recorded in the Gulf of Gdańsk indicated that the studied sediments were deposited in fresh-water lacustrine conditions at the Late Glacial to Early Holocene, which subsequently were covered by marine sands during the Holocene marine transgression. These results confirm and consolidate inferences based on previously published data on ostracods from the western part of the Gulf (KRZYMIŃSKA et al., 2005; KRZYMIŃSKA and PRZEZDZIECKI, 2010) as well as on other biotic (molluscs: KRZYMIŃSKA, 2001 and diatoms: WITKOWSKI, 1994; WITAK, 2000) and abiotic (seismoacoustic and lithological: KRZYMIŃSKA and PRZEZDZIECKI, 2010) indices from this area.

5. Acknowledgements

This study was supported by funds from the Polish National Science Centre (project no. N N307 664140). MARTA NEUMANN and PIOTR PRZEZDZIECKI (both from Polish Geol. Inst.-National Res. Inst., Mar. Geol., Gdańsk) are thanked for the help in preparing the figures. We are also grateful to PETER FRENZEL (Inst. Geosc., Univ. Jena, Germany) and an anonymous reviewer for their useful comments and suggestions on the manuscript.

6. References

BRODNIEWICZ, I., 1972: Brenkowo. Faunal analysis. – In: R. GALON (ed.), Guide-book of the excursions. International Conference of INQUA, Sub-commission on shorelines of northwestern Europe. – Pol. Acad. Sci., Comm. Quaternary Res., Warsaw, pp. 29–32.

BRODNIEWICZ, I., 1979: Faunistic analysis of Late Glacial fresh water deposits from the sea-cliff near Ustka town (Poland). – In: W. GROCHOLSKI (ed.), Od czwartorzędu do prekambru. – Ser. Geol. Univ. Adam Mickiewicz, 9, Poznań, pp. 3–27 (in Polish with Engl. abstr.).

BRODNIEWICZ, I. and B. ROSA, 1967: The boring hole and the fauna at Czołpino, Poland. – Baltica 3: 61–86.

CLARKE, K. R. and R. N. GORLEY, 2006: PRIMER v6: User manual/tutorial. PRIMER-E, Plymouth.DANIELOPOL, D. L., P. CARBONEL and J. P. COLIN (eds.), 1990: Cytherissa the Drosophila of paleolim-

nology. – Bull. Inst. Géol. Bassin d’Aquitaine, Bordeaux 47–48: 1–310.FRENZEL, P. and I. BOOMER, 2005: The use of ostracods from marginal marine, brackish waters as bio-

indicators of modern and Quaternary environmental change. – Palaeogeogr. Palaeoclimat. Palaeoecol. 225: 68–92.

FRENZEL, P., D. KEYSER and F. A. VIEHBERG, 2010: An illustrated key and (palaeo)ecological primer for Postglacial to Recent Ostracoda (Crustacea) of the Baltic Sea. – Boreas 39: 567–575.

GEIGER, W., 1993: Cytherissa lacustris (Ostracoda, Crustacea): Its use in detecting and reconstructing environmental changes at the sediment-water interface. – Verh. Int. Ver. Theor. Angew. Limnol. 25: 1102–1107.

GRIFFITHS H. I., 1995: European Quaternary freshwater Ostracoda: a biostratigraphic and palaeobiogeo-graphic primer. – Scopolia 34: 1–168.

GRIFFITHS, H. I. and J. A. HOLMES, 2000: Non-marine ostracods and Quaternary palaeoenvironments. – Quaternary Research Association, London, Technical Guide 8: 1–188.



JANISZEWSKA-PACTWA, H., 1973: Variability of the hydrological and biological relations on the base of the results of the investigations of the fauna contained in the bottom sediments of the Vistula Lagoon and Lake Druzno. – Przegl. Geofiz. 25: 133–140 (in Polish with Engl. abstr.).

JUGGINS S., 2007: C2 Version 1.5 User guide. Software for ecological and palaeoecological data analysis and visualisation. Newcastle University, Newcastle upon Tyne, UK.

KOPCZYŃSKA-LAMPARSKA, K., A. CIEŚLA and S. SKOMPSKI, 1984: Evolution of fossil lake basins of the Late Glacial and Holocene in the cliff near Niechorze (Pomerania Lakeland, Poland). – Quatern. Stud. Poland 5: 39–58.

KRZYMINSKA, J., 2001: Assemblages of molluscs in the Quaternary deposits of the southern Baltic Sea. – Biul. Pol. Geol. Inst. 397: 67–116 (in Polish with Engl. summ.).

KRZYMIŃSKA, J., G. MIOTK-SZPIGANOWICZ and M. WITAK, 2005: Biostratigraphical investigations of the Puck Bay Quaternary deposits. – Geologia i geomorfologia Pobrzeża południowego Bałtyku, Pomor-ska Akademia Pedagogiczna, Słupsk 6: 21–38 (in Polish).

KRZYMIŃSKA, J. and P. PRZEZDZIECKI, 2001: Palaeogeography of Late Glacial and Lower Holocene lakes in the Pomeranian Bay area on the basis of malacofauna and ostracods and seismoacoustic data. – Stud. Quatern. 18: 3–10.

KRZYMIŃSKA, J. and P. PRZEZDZIECKI, 2010: Fossil lacustrine bodies in the Gulf of Gdańsk as recorded by seismoacoustic data and ostracodological analysis. – Baltica 23: 25–32.

LAMPE, R., 2005: Lateglacial and Holocene water-level variations along the NE German Baltic Sea coast: review and new results. – Quatern. Int. 133–134: 121–136.

MEISCH, C., 2000: Freshwater Ostracoda of Western and Central Europe. Spectrum Akademischer Ver-lag, Heidelberg.

MOJSKI, J. E., 2000: The evolution of the southern Baltic coastal zone. – Oceanologia 42: 285–303.MOJSKI, J. E., R. DADLEZ, B. SŁOWAŃSKA, S. UŚCINOWICZ and J. ZACHOWICZ (eds.), 1995: Geological

Atlas of the Southern Baltic, 1 : 500000. Polish Geol. Inst., Warsaw.NAMIOTKO, T.: Musselshrimps (Ostracoda). – In: W. BOGDANOWICZ, E. CHUDZICKA, I. PILIPIUK and

E. SKIBIŃSKA (eds.), Fauna of Poland. Characteristics and checklist of species, vol. 5. – Mus. Inst. Zool., Polish Acad. Sci., Warsaw (in press).

NAMIOTKO, T., 1995: Subfossil Ostracoda from deep lake habitats in N. Poland. – In: J. ŘIHA (ed.), Ostracoda and biostratigraphy. – Balkema, Rotterdam, pp. 311–319.

NAMIOTKO, T., 1998: Changes in the profundal lacustrine ostracod fauna as an indicator of environ-mental perturbations in Polish lakes undergoing eutrophication. – Bull. Centr. Rech. Explor.-Prod. Elf-Aquitaine, Mémoires 20: 117–124.

NAMIOTKO, T., L. NAMIOTKO and A. WYSOCKA, 2012: Distribution of subfossil Ostracoda assemblages in lacustrine profundal sediments of north-eastern Poland. – Rev. micropal. 55: 17–27.

RÖSSLER, D., M. MOROS and W. LEMKE, 2011: The Littorina transgression in the southwestern Baltic Sea: new insights based on proxy methods and radiocarbon dating of sediment cores. – Boreas 40: 231–241.

SYWULA, T., 1974: Musselshrimps (Ostracoda). – In: Freshwater Fauna of Poland, vol. 24. – Inst. Zool. Polish Acad. Sci., PWN, Warsaw-Poznań, pp. 1–315 (in Polish).

SYWULA, T. and E. PIETRZENIUK, 1994: Class Ostracoda Latreille, 1806. – In: E. RÜHLE (ed.), Geology of Poland, Vol. 3. Atlas of guide and characteristic fossils, Part 3b. Cainozoic, Quaternary. – Polish Ecological Agency Publishing House, Warsaw, pp. 75–90.

ŪSAITYTĖ, D., 2000: The geology of the southeastern Baltic Sea: a review. – Eart-Sci. Rev. 50: 137–225.UŚCINOWICZ, S., 2006: A relative sea-level curve for the Polish Southern Baltic Sea. – Quatern. Int.

145–145: 86–103.UŚCINOWICZ, S. and J. ZACHOWICZ, 1994: Geological Map of the Baltic Sea Bottom 1 : 200000, Explana-

tory note; Sheets: Gdańsk, Elbląg, Gdańsk Deep. Polish Geol. Inst., Warsaw (in Polish).VIEHBERG, F. A., P. FRENZEL and G. HOFFMANN, 2008: Succession of late Pleistocene and Holocene

ostracode assemblages in a transgressive environment: A study at a coastal locality of the southern Baltic Sea (Germany). – Palaeogeogr. Palaeoclim. Palaeoecol. 264: 318–329.

WITAK, M., 2000: A diatom record of Late Holocene environmental changes in the Gulf of Gdańsk. – Oceanol. Stud. 29: 57–74.

WITKOWSKI, A., 1994: Recent and fossil diatom flora of the Gulf of Gdańsk, Southern Baltic Sea. – Bibl. Diatomol. 28: 1–313.

Manuscript submitted February 17th, 2012; reviesed March 31st, 2012; accepted May, 11th, 2012

Documents

Late Glacial and Holocene Ostracoda of the Gulf of Gdańsk, the Baltic Sea, Poland