zooplankton exported from lake adamowo by the river drawa

1Zoologica
29
ZOOPL
ANKTO
N-EXPO
RTED-FROM-LAKE-ADAMOWO
Poloniae
(2004)
49/1-4:
129-147
129
ZOOPLANKTON EXPORTED FROM LAKE ADAMOWO
BY THE RIVER DRAWA
R OBERT C ZERNIAWSKI
Departament of Hydrobiology, University of Agriculture in Szczecin,
Faculty of Food Sciences and Fisheries, ul. K. Królewicza 4, 71-550 Szczecin
e-mail: [email protected]
Abstract. Zooplankton collected from two sampling sites in the river Drawa
(Drawa National Park, NW Poland): outflow from the Lake Adamowo and 1.5 km below
outflow was examined. The maximum of zooplankton abundance at site I appeared in
August, the minimum - in November. In site II the maximum was observed in August,
the minimum - in February. The maximum biomass in site I occurred in August, the
minimum - in April; in site II the respective extremes were observed in August and
January. The zooplankton abundance and biomass decreased with increasing distance
from the lake. In May a nearly 60-fold reduction in abundance and biomass between
two sites was recorded. Different species were often observed in the two sites. The
differences in abundance and qualitative structure of zooplankton probably resulted
from the overflow expanse and predation pressure on zooplankton by fish fry.
INTRODUCTION
It is generally known that outflows of natural water basins remove large
quantities of planktonic animals of the biomass reaching even several hundred
of kilograms during 24 h. According to S ZLAUER (1974), even small streams
remove from lakes considerable quantities of zooplankton. This phenomenon is
observed in the in outflows where fish fry gathers, feeding mainly on zooplankton, which is the basic component of their diet. The large numbers of feeding
fry, observed in the outflow of the river Drawa from Lake Adamowo inducated
me to investigate the zooplankton carried by the river.
X V I I I C o n g r e s s o f P o l i s h Z o o l o g i c a l S o c i e t y, 1 5 - 1 8 S e p t e m b e r 2 0 0 3 , To r u ñ , P o l a n d
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R.-CZERNIAWSKI
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The objective of this paper was an estimate of abundance and biomass of
plankton removed throughout a year. Another aim was an assessment of the
influence of overflow expanse of the river Drawa on the quantitative and qualitative characteristics of the zooplankton, as well as to reveal changes depending on the distance from lake.
SUDY AREA
Zooplankton was collected in 2002 in two sites on the Drawa river, in the
Drawa National Park. The first site was situated at the outflow of the river from
the eutrophic Lake Adamowo, the second - 1.5 km below. Above the second site
the Drawa overflows in the area of 2 ha (Fig.1). In site I samples were taken from
April to November, due to the ice cover on the shore; in site II - from January
to December.
Fig. 1. Location of sites of zooplankton sampling.
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ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
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Lake Adamowo (120.4 ha) is situated on the Równina Drawska. It is a flow
lake, eutrophicated, located in the buffer zone of the Drawa National Park, on
the River Drawa. Its northeastern shore adjoins the town Drawno. Lake Adamowo
is indirectly connected in the east with the flow Lake Gra¿yna (75.8 ha) and fed
by three smaller creeks: Bagnica - polluted with wastewaters from nearby farms,
and running dry in summer, Sitna - a clear, forest stream, and the stream connecting Lake Adamowo with Lake Krzywy Róg (32 ha). On the southern shore
a drainage ditch discharges its water into the lake; besides a part of municipal
sewage enters the lake through the storm outlet. The lake is distinctly divided
in two parts. One the part has little diversified bottom and small depth. According to fishery classification of lakes this part is of pikeperch type. The other
stagnant - is deep, with steep shores, and can be classified as a bream type
water body.
In Lake Adamowo algal blooms are frequent, influencing the transparency
of water. The shores of the flow part of lake are overgrown with submerged and
emergent vegetation: common hornwort (Ceratophyllum demersum), water milfoil (Myriophyllum spicatum), common reed (Phragmites communis), white water-lily (Nymphaea alba), yellow pond- lily (Nuphar luteum), calamus (Acorus
calamus) and broad-leaved cat-tail (Typha latifolia).
The aquatic fauna of the lake includes thick-shelled river mussel (Unio
crassus) and zebra mussel (Dreissena polymorpha), inhabiting abundantly the
sandy bottom and submerged objects; the most frequent fish species being:
bream (Abramis brama), white bram (Abramis bjoerkna), roach (Rutilus rutilus),
perch (Perca fluviatilis), pike (Esox lucius), pikeperch (Sander lucioperca), eel
(Anguilla anguilla) and chub (Leuciscus cephalus).
Above site II, the river Drawa overflows an the area of about 2 ha. Over
70% of the floodplain is overgrown by submerged and emergent vegetation,
which provides shelter to masses of fish fry and adult fishes, especially the
bitterling (Rhodeus sericeus). Among the macrophytes, the following species
dominate: common hornwort (Ceratophyllum demersum), perfoliate pondweed
(Potamogeton perfoliatus), water milfoil (Myriophyllum spicatum). On the eastern
side, the floodplain is surrounded by ploughed fields and meadows, on the western
side - by a deciduous forest. The maximum depth of overflow expanse is 4 m.
MATERIAL AND METHODS
Two samples were taken in each site: one quantitative (filtering 100 dm 3 of
water through the bolting gauze, 25 µm) to determine the abundance of individuals, another - qualitative, aimed at the determination of species recorded. The
zooplankton was qualitatively and quantitatively analysed. Females and males
of particular groups of crustaceans were counted separately; number of rotifers
were determined as well as larval stages of insects. Abundance of zooplankton
was given per 1 dm 3. In each sample the length of specimens representing one
species was measured. The measurements were employed in estimation of the
biomass of zooplankton. Tables by S TARMACH (1955) and M ORDUCHAJ -B O£TOWSKA
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R.-CZERNIAWSKI
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(1954) were used for the length-weight conversion. Species were identified
using keys of R YBAK (2000), W AGLER (1937), K IEFER and F RYER (1978), and
K UTIKOWA (1970).
The calculated values of the zooplankton biomass and of the water-flow,
were used to estimate wet weight of the zooplankton exported by the river in
kg/24 hrs. The flow rate was measured with the aid of stop-watch. The flow
intensity was established using depth and flow rate measurements in hydrometric profiles, with the formula: Q = V/t [m -3 s], where: Q - flow intensity, V - water
quantity, t - flow time (D ÊBSKI , 1970).
Taxonomic similarity between the sites was calculated according to the
formula of Marczewski and Steinhaus (after ROMANOWICZ , 1998): S = W/a + b - w,
where: S - similarity of two sites compared, a - number of species in site A, b - number
of species in site B, W - species in common.
Zooplankton diversity was calculated with the Shannon - Wiener index
(KREBS, 1996):
H=- S (p i )(log 2 p i ), where: H - diversity, p i - contribution of "i" species to
the sample;
pi = N i/N, where: N i - abundance of taxon "i", N - total abundance of all taxa;
In case of comparison between sites: N i - number of taxa in one site, N number of taxa in two compared sites.
Measurements of water temperature were performed as well.
RESULTS
In both sites, representatives of seven groups were recorded: Rotatoria,
Cladocera, Copepoda, Insecta, Mollusca, Nematoda, Tardigrada (Tabs 1-3). Results of taxonomical similarity and diversity of two sites compared are presented
in Table 4.
In site I larvae of Dreissena polymorpha dominated (maximum in August
512.8 ind.•dm -3). Besides, the following crustacean species occurred in the greatest numbers: Bosmina longirostris (maximum in November 15.8 ind.•dm -3), B.
coregoni (maximum in May 9 ind.•dm -3), Daphnia longispina (maximum in August 4.2 ind.•dm -3), D. cucullata (maximum in August 1.8 ind.•dm-3), Bythotrephes
longimanus (maximum in August 1.4 ind.•dm-3 ).
Relatively numerous were also larval forms of copepods: nauplii of Cyclopoida
(maximum in August 15.2 ind.•dm -3 ), and of Calanoida (maximum in April
6 ind.•dm -3), copepodites of Cyclopoida (maximum in August 5.8 ind.•dm-3 ).
The most abundantly represent rotifer genera were: Synchaeta (maximum in May
87 ind.•dm-3), Asplanchna (maximum in May 56.4 ind.•dm-3), Polyarthra (maximum
in June 24.8 ind.•dm -3, in July 23.25 ind.•dm -3 and in September 21.6 ind.•dm -3 ),
the most abundant species being: Keratella cochlearis (maximum in September
14.7 ind.•dm -3 and in August 14,6 ind.•dm -3 ). Unidentified naked rotifers reached
an abundance peak in September (54.5 ind.•dm-3). The total maximum of zooplankton
abundance occurred in August - 587.4 ind.•dm -3 , the minimum - in November
- 37.4 ind.•dm -3 (Table 5).
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Table 1
Qualitative composition of crustaceans recorded in 2002 in the river Drawa in sites I and II
ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
133
in sites I and II
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Table 2
Nematoda, Mollusca, Insecta and Tardigrada recorded in the river Drawa
R.-CZERNIAWSKI
134
135
Table 3
Qualitative composition of rotifers recorded in 2002 in the river Drawa in sites I and II
ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
135
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R.-CZERNIAWSKI
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Table 4
Taxonomic similarity (S) and taxonomic diversity (H) based on the qualitative
analysis of zooplankton in the river Drawa in the two sites in 2002
The highest biomass in site I was recorded for larvae of Dreissena polymorpha
which in August reached 0.4512 mg dm -3. The next group of high biomass
included cladoceran species: Bythotrephes longimanus (maximum in August
0.448 mg•dm-3), Bosmina coregoni (maximum in May 0.1012 mg •dm-3), B. longirostris
(maximum in November 0.0977 mg dm -3 ), Daphnia longispina (maximum in August 0.063 mg•dm -3). Among rotifers, species of genera Asplanchna (maximum in
September 0.1125 mg•dm -3) and Synchaeta (maximum in May 0.0783 mg•dm -3), as
well as Brachionus calyciflorus (maximum in May 0.0744 mg•dm -3 ) were
characterised by a high biomass. The biomass of Nematoda was also significant,
with the maximum in June 0.12 mg•dm -3 , as well as that of chironomid larvae
(maximum in August 0.2 mg•dm -3 ).
The total maximum of the zooplankton biomass appeared in August 1.3588 mg•dm -3 , the minimum - in April - 0.0472 mg•dm -3 (Table 6).
In site I the river Drawa removed from Lake Adamowo: in April - 21 kg of zooplankton per 24 h, in May - 440 kg/24 h, in June - 105 kg/24 h, in July - 81 kg/24 h,
in August - 744 kg/24 h, in September - 101 kg/24 h, in October - 92 kg/24 h.
In site II larvae of Dreissena polymorpha (maximum in August 139.75
ind.•dm -3) were the most numerous. Apart from this group, the following crustacean species were very abundant: Bosmina coregoni (maximum in August 2
ind.•dm -3), B. longirostris (maximum in September 1.5 ind.•dm -3), Daphnia cucullata
(maximum in August 0.75 ind.•dm -3 ), Chydorus sphaericus (maximum in August
0.5 ind.•dm -3), Bythotrephes longimanus (maximum in August 0.25 ind.•dm -3 ).
Also larval forms of copepods: nauplii of Cyclopoida (maximum in July 4.2
ind.•dm -3 and 4 ind.•dm -3 in August), and of Calanoida (maximum in June 1.9
ind.•dm -3 and 0,3 ind.•dm -3 in December), copepodites of Cyclopoida (maximum
in August 1.75 ind.•dm -3), and of Calanoida (maximum in July 0.3 ind.•dm -3 ),
were rather numerous. Among rotifers, the most numerous were: Synchaeta sp.
(maximum in August 52.5 ind.•dm -3), Keratella cochlearis (maximum in August
33.5 ind.•dm -3), Polyarthra sp. (maximum in September 21.3 ind.•dm-3), Keratella
quadrata (maximum in December 15.8 ind.•dm -3 ), and Asplanchna (maximum in
September 6 ind.•dm -3 ). Unindentified naked rotifers reached their maximum in
August (49 ind.•dm -3 ).
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137
The total maximum of zooplankton abundance occurred in August - 286
ind.•dm -3 , the minimum in February - 2.45 ind.•dm -3 (Table 7) .
The highest biomass in site II was recorded for larvae of Dreissena
polymorpha which in August reached 0.1229 mg•dm -3 . Another group of high
biomass included the following cladoceran species: Bythotrephes longimanus
(maximum in August 0.0875 mg•dm-3), Bosmina coregoni (maximum in August
0.0331 mg•dm -3), Thermocyclops sp.(maximum in April 0.0151 mg•dm -3), Daphnia
cucullata (maximum in August 0.0127 mg•dm -3), Bosmina longirostris (maximum
in September 0.0117 mg•dm -3).
Larval stages of Cyclopoida were characterised by a relatively high biomass,
with the maximum in August 0.0207 mg•dm -3. Among rotifers, species of the
genera Asplanchna (maximum in September 0.1044 mg•dm -3 ), and Synchaeta
(maximum in August 0.0525 mg•dm -3) were characterised by a high biomass. The
biomass of Nematoda and Chironomidae was 0.045 mg•dm-3 in April and 0.045
mg•dm -3 in November, respectively.
the total maximum of the zooplankton biomass occurred in August - 0.3879
mg•dm -3, the minimum in January - 0.0102 mg•dm -3 (Table 8).
In site II the river Drawa exported in January - 5 kg zooplankton / 24 h,
in February - 9 kg / 24 h, in March - 7 kg / 24 h, in April - 39 kg / 24 h, in May
- 11 kg / 24 h, in June - 28 kg / 24 h, in July - 56 kg / 24 h, in August - 220
kg / 24 h, in September - 132 kg / 24 h, in October - 37 kg / 24 h, in November
- 17 kg / 24 h, in December - 38 kg / 24 h.
DISCUSSION
The qualitative and quantitative composition of river zooplankton, removed
from water bodies is entirely dependent on the species inhabiting lakes situated
on the rivers (R OMANOWICZ , 1998). Its abundance gets reduced with increasing
distance from the river outflow. In smaller streams the water current precludes
reproduction of planctonic organisms, which reproduce in still bays, ponds,
lakes (S TARMACH et al., 1978) and floodplains. Small depth and width of streams,
as well as lower temperature compared to lakes, determine the rate of reproduction and development, and result in relatively low abundance of zooplankton in
such places (C ZERNIAWSKI and C ZERNIEJEWSKI , 2003).
S TARMACH 's (1978) statement that there is no specific river plankton comprising species which would not occur in stagnant waters, seems to be true.
The zooplankton removed from Lake Adamowo was subject to reduction
between the two sites. In site II the number of big crustaceans markedly decreased:
- Bythotrephes longimanus (from 1.4 ind.•dm -3 in site I, to 0.25 ind.•dm -3 in site
II), and Daphnia cucullata from 1.8 ind.•dm-3 in site I, to 0.75 ind.•dm-3 in site
II, in August). S ZLAUER (1977) showed a similar dependence in the study on
zooplankton removed by the river P³onia from Lake P³oñ, where 8 kilometers
away from the lake nearly a complete disappearance of big crustaceans from the
river plankton was noted. However, R OMANOWICZ (1998) investigating a 7 km
section of the river P³ociczna found only an insignificant reduction (31%) of big
components of zooplankton. In this study in May, between the two sites the
zooplankton abundance and biomass was reduced nearly 60 times. In August,
the reduction was nearly as much as three times.
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Table 5
Abundance (ind./dm 3 ) of zooplankton taxa in the river Drawa in site I
R.-CZERNIAWSKI
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ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
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Table 6
Biomass (mg/dm 3 ) of zooplankton taxa in the river Drawa in site I
R.-CZERNIAWSKI
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ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
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Table 7
Abundance (ind./dm 3 ) of zooplankton taxa in the river Drawa in site II
R.-CZERNIAWSKI
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ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
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Table 8
Biomass (mg/dm3) of zooplankton taxa in the river Drawa in site II
R.-CZERNIAWSKI
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ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
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Apart from quantitative changes, differences in the qualitative structure
between the two sites were observed. Species found in the outflow from the
lake, and not recorded from site II, are: Asplanchna sp. (in May), Bosmina
coregoni (in May), B. longirostris (in May), Bythotrephes longimanus (in May),
Daphnia longispina (in August). In site II Chydoridae, Alonidae were found,
which were often not noted in site I. The differences result probably from the
presence of well-developed vegetation in the floodplain, producing suitable
habitats for these littoral taxa. The larval stages of copepods, which according
to E JSMONT -K ARABIN and WÊGLEÑSKA (1996) are more resistant to the hydrobiological stress constituted a larger part of its community.
In the zooplankton in site I and site II small planktonic species dominated
qualitatively and quantitatively. P IASECKI (2003), who examined zooplankton
abundance in Lake Pe³cz recorded a dominance of Rotatoria as well as small
forms of Cladocera, which suggested a progressive eutrophication of the lake.
The qualitative structure of zooplankton removed from Lake Adamowo, especially high numbers of Rotatoria (site I, in August - 37.6 ind.•dm -3) and small
forms of Copepoda (site I, in August - 21.2 ind.•dm -3) and Cladocera (site I, in
August - 7.4 ind.•dm -3), may suggest eutrophication of this water body.
The differences in qualitative and quantitative composition of the zooplankton probably results from the existance of the floodplain - an excellent place
for zooplankton feeding and reproduction, as well as for fish fry of various
species foraging for planctonic animals.
ZOOPLANKTON WYNOSZONY Z JEZIORA ADAMOWO PRZEZ RZEKÊ DRAWÊ
STRESZCZENIE
Badano zooplankton rzeki Drawy, który pozyskiwano w roku 2002 z dwóch
stanowisk znajduj¹cych siê na terenie Drawieñskiego Parku Narodowego.
Stanowisko pierwsze znajdowa³o siê przy wyp³ywie rzeki Drawy z eutroficznego
jeziora Adamowo. Stanowisko drugie znajdowa³o siê w odleg³oœci ok. 1,5 km od
wyp³ywu rzeki z jeziora. Powy¿ej stanowiska drugiego Drawa rozlewa siê na
powierzchni ok. 2 ha. Celem pracy by³o okreœlenie liczebnoœci i biomasy planktonu
wynoszonego w ci¹gu roku z jeziora Adamowo, oraz zbadanie jego sk³adu
gatunkowego. Drugim celem pracy by³o okreœlenie wp³ywu rozlewiska Drawy na
kszta³towanie stosunków iloœciowych i jakoœciowych zooplanktonu, a tak¿e
wykazanie zmian w liczebnoœci w miarê oddalania siê od jeziora. Ogólne maksimum
liczebnoœci zooplanktonu na st. 1 przypad³o w miesi¹cu sierpniu natomiast minimum w listopadzie. Na st. 2 ogólne maksimum liczebnoœci zooplanktonu nast¹pi³o
w sierpniu natomiast minimum w lutym. Ogólne maksimum biomasy zooplanktonu
na st. 1 przypad³o na miesi¹c sierpieñ, natomiast minimum na kwiecieñ. Ogólne
maksimum biomasy zooplanktonu na st. 2 przypad³o na miesi¹c sierpieñ, natomiast
minimum na styczeñ. W miesi¹cu maju, pomiêdzy dwoma stanowiskami, nast¹pi³a
prawie szeœædziesiêciokrotna redukcja liczebnoœci i biomasy ca³ego zooplanktonu.
Oprócz zmian iloœciowych zanotowano tak¿e zmiany w sk³adzie jakoœciowym. Na
stanowisku drugim zanotowano obecnoœæ rodzin Chydoridae, Alonidae, których
czêsto brakowa³o na stanowisku pierwszym. Prawdopodobnie g³ówn¹ przyczyn¹
147
ZOOPLANKTON-EXPORTED-FROM-LAKE-ADAMOWO
147
zmian iloœciowych i jakoœciowych by³o istnienie rozlewiska bêd¹cego doskona³ym
miejscem do rozmna¿ania i ¿erowania zooplanktonu, jak równie¿ wyjadanie jego
przez m³odociane stadia ró¿nych gatunków ryb.
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Received 30.11.2003.