The body size distribution of Filinia longiseta (Ehrenberg) in different types of small water bodies in the Wielkoposka region

Abstract

The body size distribution of Filinia longiseta (Ehrenberg) in different types of small water bodies in the Wielkoposka region Small water bodies are often characterised by speciic macrophyte species composition and different levels of predation. This may also have an effect on the body size and shape of rotifer specimens. The aim of the study was to determine the relation of the size of rotifer Filinia longiseta (body and appendages length), with respect to three speciic kinds of pond (mid-forest, pastoral and anthropogenically changed) and to three kinds of hydromacrophytes (nymphaeids, elodeids and helophytes) as well as comparatively to the open water zone. The examined water bodies also differed in presence or absence. Morphometric analysis of specimens of F. longiseta showed that both factors –the type of water body relating to different land-use in the catchment area as well as the microhabitat type– were signi predictors, innuencing their body size and spine length. Filinia longiseta specimens were signiicantly smaller in ponds situated within the pastoral catchment area. The largest specimens were found among stands of nymphaeids, while the smallest were found within the open water zone, which may indicate both the ecological requirements of this species as well as the marked innuence of in the unvegetated area.

Full text

Limnetica, 29 (1): x-xx (2008)
Limnetica, 29 (1): 171-182 (2010)
c
Asociaci´
on Ib´
erica de Limnolog´
a, Madrid. Spain. ISSN: 0213-8409
The body size distribution of Filinia longiseta (Ehrenberg) in different
types of small water bodies in the Wielkoposka region
Anna Basi´
nska, Natalia Kuczy´
nska-Kippen∗and Kasper ´
Swidnicki
Department of Water Protection, Faculty of Biology, Adam Mickiewicz Univeristy, Umultowska 89,
61-614 Pozna´
n, Poland
2
∗Corresponding author: kippen@hot.pl
2
Received: 9/12/08 Accepted: 24/6/09
ABSTRACT
The body size distribution of Filinia longiseta (Ehrenberg) in different types of small water bodies in the Wielkoposka
region
Small water bodies are often characterised by specic macrophyte species composition and different levels of predation.
This may also have an effect on the body size and shape of rotifer specimens. The aim of the study was to determine the
relation of the size of rotifer Filinia longiseta (body and appendages length), with respect to three specic kinds of pond
(mid-forest, pastoral and anthropogenically changed) and to three kinds of hydromacrophytes (nymphaeids, elodeids and
helophytes) as well as comparatively to the open water zone. The examined water bodies also differed in sh presence or
absence. Morphometric analysis of specimens of F. longiseta showed that both factors –the type of water body relating to
different land-use in the catchment area as well as the microhabitat type– were signicant predictors, inuencing their body
size and spine length. Filinia longiseta specimens were signicantly smaller in ponds situated within the pastoral catchment
area. The largest specimens were found among stands of nymphaeids, while the smallest were found within the open water
zone, which may indicate both the ecological requirements of this species as well as the marked inuence of sh in the
unvegetated area.
Key words: Body size, Filinia longiseta, rotifers, ponds, macrophytes.
RESUMEN
Distribuci´
on de tama˜
nos de Filinia longiseta (Ehrenberg) en diferentes tipos de peque˜
nas masas de agua en la regi´
on de
Wielkoposka
Las peque˜
nas masas de agua est´
an caracterizadas a menudo por la composici´
on espec´
ca de macr´
otos y diferentes niveles
de depredaci´
on. Esto puede tener efecto en el tama˜
no y la forma de los rot´
feros. El objetivo de este estudio fue determinar las
diferencias de tama˜
no (longitud del cuerpo y de los ap´
endices) del rot´
fero Filinia longiseta en tres tipos de charcas (forestales,
de pastizales y antropizadas) y en tres tipos de vegetaci´
on sumergida (ninfeidos, elodeidos y hel´
otos) as´
 como tambi´
en en
aguas libres. Las charcas examinadas difer´
an tambi´
en por la presencia o no de peces. Los an´
alisis morfom´
etricos de los
individuos de F. longiseta han mostrado que tanto el tipo de charca, seg´
un los usos del suelo en el ´
area de captaci´
on, como
el tipo de microhabitat inuencian las longitudes del cuerpo y de los ap´
endices. Los individuos de F. longiseta resultaron
ser signicativamente m´
as peque˜
nos en las charcas situadas en las zonas de pastizales. Las poblaciones con individuos de
mayor tama˜
no se encontraron en las matas de ninfeidos, mientras que en las de aguas libres se encontraba las constituidas
por individuos de menores dimensiones, lo que puede ser debido tanto a las adaptaciones de esta especie a las condiciones
del medio como a la reconocida inuencia de los peces en las zonas desprovistas de vegetaci´
on.
Palabras clave: Tam a ˜
no corporal, Filinia longiseta,rot
´
feros, charcas, macr´
otos.

172 Basi´
nska et al.
INTRODUCTION
The factors which create a specic habitat cha-
racter may also inuence the structure of zoo-
plankton communities (Burks et al., 2002; Ro-
mare et al., 2003). The variation of aquatic
vegetation, relating to morphology and the den-
sity of a plant stand, may also lead to a high-
er diversity compared to the open water zone
of both rotifer and crustaceans (Scheffer, 1998;
Kuczy´
nska-Kippen, 2007a). Moreover, the occu-
rrence and size structure of rotifers can vary bet-
ween different habitat types (Kuczy´
nska-Kippen,
2005). The biotic parameters such as sh and in-
vertebrate predators play an essential role in the
determination of body size structures and abun-
dance of zooplankton (Brooks & Dodson, 1965;
Huchinson, 1967). Planktivorous sh present
in lakes and ponds may have a size-selective
grazing effect on zooplankton which leads to
the elimination of the largest specimens from
among zooplankton communities (Irvine & Pe-
rrow, 1992). Pelagic-associated species of zoo-
plankton are often equipped with long spines
which have been recognized as a defensive me-
chanism which reduces predation by tactile pre-
dators (Gilbert, 1999). Prey equipped with spi-
nes are more difcult for predators to manipulate
where mouth size may be a limiting factor (Lam-
pert & Sommer, 2001; Radwan et al., 2004). The
development of this protective setae and the body
size structure of zooplankton species can be mo-
died by the presence/absence of sh. It has been
shown that sh kairomons may also contribu-
te to this process (Hanazato et al., 2001). Ho-
wever, Wallace (2002) states that not all kinds
of rotifer appendages function by directly inter-
fering with predatory attack. The Filinia genus
contains species that possess movable, elonga-
te, exible appendages that swing, making wide,
arc-like movements. After detecting disturban-
ces in their surroundings produced by a predator
or large suspension feeder (daphnids) such spe-
cies exhibit a series of swift jumping movements
which help them to escape.
Biotic factors such as predation and compe-
tition play an extremely signicant role in the
maintenance of plankton community structure
(Brooks & Dodson, 1965). Not only predation
but also competition between particular zooplank-
ton species may also have a decisive effect on
the structuring of the body size of particular zoo-
plankton specimens (Gilbert & MacIsaac, 1989).
Small water bodies are specic ecosystems
which function differently to large and deep la-
kes (Oertli et al., 2002) and human activity in
their catchment area may have a much greater
effect on the functioning of the ecosystem com-
pared to large water bodies (Camacho et al.,
2008). Ponds are less stable and the various roles
land-use in their immediate vicinity seems to be
of fundamental importance for the occupation of
both plants and animals (Davies, 2005). The kind
of land-use surrounding the water body may also
contribute to basic parameters which are decisive
for the composition and abundance of most zoo-
plankton organisms (George & Wineld, 2002;
Miller et al., 1997). The irregular processes that
take place in a temperate climate, e.g. wind mi-
xing or surface oods, will also inuence the
physical-chemical and biological parameters of
water, especially in the case of shallow reservoirs
(Joniak et al., 2000). The above mentioned fac-
tors affect the composition and abundance of ro-
tifer community structure; in addition they also
contribute to the size structure of particular roti-
fer species. Filinia longiseta, which is a common
and cosmopolitan planktonic rotifer usually oc-
curring in shallow lakes and variety of small wa-
ter bodies (Nogrady, 1993; Radwan et al., 2004),
is known to be a valuable indicator of eutrophic
waters (Karabin, 1985; B¯
erzin¸
s & Pejler, 1989;
Ejsmont-Karabin, 1995). Even though Filinia is
an indicator of eutrophy, it has also been found
in mesotrophic lakes (M¨
aemets, 1983). Although
taxonomic problems in this genus are still unre-
solved (Sanoamuang, 1993), some authors dis-
tinguish several forms or subspecies within this
species (Koste et al., 1978; Radwan et al., 2004),
which according to Nogrady (1993) are separate
species. Therefore in the present study this rotifer
is described as Filinia longiseta-complex, inclu-
ding its various forms. Both the occurrence and
number of zooplankton are often modied by the
habitat preference of a species, this is connected
with overall food conditions which occur within

Filinia longiseta body size in Wielkoposka ponds 173
a particular water body (de Azavedo & Bonecker,
2003). Filinia species feed well on detritus, bac-
teriaaswellasonChlorococcales (Koste et al.,
1978; Nogrady, 1993; Radwan et al., 2004).
Therefore, the aim of this study was to deter-
mine the relationship between individuals of Fi-
linia longiseta (Ehrenberg) representing different
body sizes within specic types of ponds (mid-
forest, pastoral and anthropogenically changed)
and within different habitats (open water zone as
well as within two kinds of hydromacrophytes
–nymphaeids and helophytes).
MATERIAL AND METHODS
This study analyzed samples collected from 31
stations within 19 small water bodies located
in the Wielkopolska region of western Poland
(Table 1). At least 30 individuals of Filinia lon-
giseta were measured from among ten stations
in seven water bodies. The type of land-use in
the catchment area, type of aquatic vegetation as
well as predation pressure differed among par-
ticular ponds. The examined water bodies we-
re classied into three groups depending on the
Tabl e 1 . Characteristics of examined ponds indicating the sampled stations. Size of the ponds stated as categories: 1-very small
(<0.5ha), 2-small, 3-small/medium, 4-medium, 5-big, 6-very big (5 ha). Caracter´
sticas de las charcas estudiadas con indicaci´
on
de las estaciones de muestreo. Tama˜
no de las charcas seg´
un las siguientes categor´
as: 1-muy peque˜
na (<0.5 ha), 2 peque˜
na, 3
peque˜
na-media, 4 media , 5 grande y 6 muy grande (5 ha).
POND NAME DATE
CATCHMENT
AREA
POND
SIZE
POND
DEPTH (m)
FISH
PRESENCE STATION
01 Batorowo 25.06.04 ANTROPOGENIC 3 0.5 ABSENT WATER *
(Pozna´
n) PHRAGMITES AUSTRALIS
02 Marcelin 22.06.04 ANTROPOGENIC 4 3.5 PRESENT PHRAGMITES AUSTRALIS *
(Pozna´
n) POLYGONUM AMPHIBIUM *
WATER *
03´
Sw. Jerzy 22.06.04 ANTROPOGENIC 04 1.0 PRESENT TYPHA ANGUSTIFOLIA *
(Pozna´
n) WATER *
4 Klempicz 18.06.05 ANTROPOGENIC 2 0.6 PRESENT WATER
POTAMOGETON NATANS
TYPHA ANGUSTIFOLIA
05 Owcza 20.07.05 ANTROPOGENIC 5 0.5 ABSENT CERATOPHYLLUM DEMERSUM
WATER
06Coto
´
n 23.06.06 FIELD 4 1.1 PRESENT WATER *
07Klon
´
owiec 27.07.06 FIELD 5 3.5 ABSENT WATER *
08 Przysieka 24.06.06 FIELD 1 1.0 PRESENT WATER *
09Da¸br´
owka 20.06.04 FIELD 3 0.7 PRESENT PHRAGMITES AUSTRALIS
POTAMOGETON PECTINATUS
10 Pale¸dzie 25.06.04 FIELD 4 1.5 PRESENT WATER
POTAMOGETON CRISPUS
11 Piotrowo 16.06.02 FIELD 1 1.0 PRESENT CHARA FRAGILIS
12 Tarnowo 8 12.07.06. FIELD 2 0.8 PRESENT NUPHAR LUTEUM
13 Tarnowo 21 18.06.05 FIELD 3 2.0 ABSENT WATER
14 Kraj Warty 19.06.05 FOREST 4 1.5 ABSENT WATER *
15 Gazbruchy M 10.06.04 FOREST 5 0.6 ABSENT POA ANNUA
WATER
16 Gazbruchy W 10.06.04 FOREST 6 1.0 ABSENT SCHOENOPLECTUS LACUSTRIS
POTAMOGETON LUCENS
WATER
17 Hindak 09.06.04 FOREST 5 0.5 ABSENT WATER
18 Mikowo 18.06.05 FOREST 5 1.2 ABSENT WATER
19 Obrzycko 17.06.06 FOREST 2 0.5 ABSENT WATER *
* Station where Filinia longiseta was found in representative numbers.

174 Basi´
nska et al.
character of the surrounding area: forest, field
and anthropogenically modified, situated in urban
places. Of the ponds in which Filinia longiseta
was found, three were situated within the strongly
anthropogenically modified city of Pozna´
n (ponds
numbered: 1, 2, 3), three water bodies were
located within the pastoral catchment area (ponds
numbered: 6, 7, 8) and only one within the forest
catchment area (pond number: 14) (Table 1).
The aquatic vegetation in the ponds differed and
represented three ecological groups: nymphaeids,
elodeids and helophytes. The helophytes were
represented by Schoenoplectus lacustris (L.),
Phragmites australis (Cav.) Steud and Typha an-
gustifolia (L.). Among nymphaeides three species
were identified: Polygonum amphibium (L.), Po -
tamogeton natans (L.) and Nuphar luteum (L.).
The highest variety of species was recorded in
the group of submerged plants: Chara fragilis
(Desv.), Ceratophyllum demersum (L.), Poa an-
nua (L.), Potamogeton crispus (L.), Potamoge-
ton lucens (L.) and Potamogeton pectinatus (L.).
The examinated water bodies also differed
with respect to sh presence. Fish were present
in 8 of the 19 ponds (Table 1).
Samples were collected in the summer period
between 2002 and 2005 from single-species plant
stands or unvegetated stands, which are called open
water stations. A plexiglass core sampler was used
to sample the macrophyte-dominated stations. The
collected material, taken in triplicate at each site,
was concentrated using a 45-μm plankton net and
was fixed immediately with 4 % formalin. The
water chemistry at particular stations included to-
tal phosphorus, total nitrogen and chlorophyll a.
Filinia longiseta specimens were measured at
the longest part of the animal’s body and two spines
–the lateral and also the caudal seta were measured
separately in least 30 specimens in each sample.
Analysis of variance (ANOVA) with posteriori
Tukey test was used to identify the differences in
body size of individuals of rotifer species between
particular kinds of habitats, including hydroma-
crophytes and the open water zone and also bet-
ween particular types of water bodies (N=303).
RESULTS
Filinia longiseta was found within seven of the
nineteen water bodies and in ten of the thirty one
investigated stations. An abundance of this spe-
cies were found in pond 1 within the open wa-
ter zone (695 ind L−1±371 SD), pond 7 within
the open water area (899 ind L−1±255 SD) and
in pond 2 in samples taken from the Phragmi-
Tabl e 2 . Total phosphorus-TP [mg/L], total nitrogen-TN [mg/L] and chlorophyll a-Chl a[μmg/L] concentration compared with
density [mean ind L−1], mean body length [μm] and mean seta lengths [μm] of Filinia longiseta in particular stations among different
type of ponds. F´
oforo total TP [mg/L], nitr´
ogeno total TN [mg/L] y clorola aChla[μmg/L] junto con la densidad media [ind L−1]y
la longitud media del cuerpo y de los ap´
endices [μm] de Filinia longiseta en cada una de las estaciones de muestreo en los diferentes
tipos de charcas.
POND
CATCHMENT
AREA
FISH
PRESENCE STATION TP TN Chl a Density
Body
length
Lateral
setae
length
Caudal
seta
length
01 ANTHROPOGENIC ABSENT WATER 0.2802.837 363.6 603 173.47 354.53 177.20
02 ANTHROPOGENIC PRESENT PHRAGMITES AUSTRALIS 0.0401.258 3.85 791 174.27 497.67 261.23
POLYGONUM AMPHIBIUM 0.0301.485 2.57 296 208.67 579.33 244.93
WATER 0.1001.844 0.001 033 189.47 598.00 313.60
03 ANTHROPOGENIC PRESENT TYPHA ANGUSTIFOLIA 0.0201.596 74.84 046 170.48 668.38 371.00
WATER 0.0701.188 9.41 069 229.47 891.07 456.13
06 FIELD PRESENT WATER 0.085 1.764 9.84 051 141.72 304.64 197.87
07 FIELD ABSENT WATER 0.4603.204 — 899 150.13 384.53 243.03
08 FIELD PRESENT WATER 0.0201.535 81.26 033 171.38 366.30 296.93
14 FOREST ABSENT WATER 0.1701.240 48.65 029 184.80 767.67 384.53

Filinia longiseta body size in Wielkoposka ponds 175
Mean
Mean±SE
field forest anthrop
150
155
160
165
170
175
180
185
190
195
200
μm
Figure 1. Filinia longiseta body length in different ty-
pes of water bodies (forest-mid-forest, eld-pastoral, anthrop-
anthropogenically modied). Longitud del cuerpo de Filinia
longiseta en diferentes tipos de charcas (forest = forestales,
eld = de pastizales y anthrop = antropizadas).
tes australis stand (mean 791 ind L−1±211 SD).
The smallest abundance of Filinia longise-
ta was recorded in the open water zone
in pond 6 (mean 33 ind L−1±2 SD), pond 8
(mean 35 ind L−1±33 SD) and in pond 14 (mean
44 ind L−1±55 SD) (Table 2).
Mean
Mean±SE
water heloph nymph
165
170
175
180
185
190
195
200
205
210
215
μm
Figure 2. Filinia longiseta body length in different ecological
habitat types (water-open water zone, heloph-helophytes and
nymph-nymphides stands). Longitud del cuerpo de Filinia lon-
giseta en diferentes tipos de h´
abitats (water = aguas libres, he-
loph = hel´
otos y nymph = ninfeidos).
Morphometric analyses of specimens of Fi-
linia longiseta included data from various sta-
tions located in seven reservoirs (pond numbers:
1, 2, 3, 6, 7, 8, 14) and showed differences in
the body length value between water bodies su-
rrounded by different types of catchment area,
Tabl e 3 . Results of Tukey tests, signicance level: * <0.05, ** <0.01, *** <0.001 and ns-not signicant for differences of Fi-
linia longiseta body length, lateral setae length and caudal seta length among different types of ponds (forest-mid-forest, eld-
pastoral, anthrop-anthropogenically modied) and among different habitats (water-open water zone, heloph-helophytes and nymph-
nymphaeids stands). Resultados de las pruebas de Tukey, niveles de signicaci´
on: * <0.05, ** <0.01, *** <0.001 y ns-no signicativo
para las diferencias en las longitudes del cuerpo, de las setas laterals y de la seta caudal de Filinia longiseta entre los diferentes
tipos de charcas (forest-forestales, eld-de pastizales, anthrop-antr ´
opicas) y entre los diferentes habitats: water-zona de aguas libres,
heloph-hel´
otos y nymph-ninfeidos).
body length
pondtype eld forest anthrop mtype water heloph nymph
eld *** *** water ns ***
forest *** ns heloph ns ***
anthrop *** ns nymph *** ***
lateral setae length
pondtype eld forest anthrop mtype water heloph nymph
eld *** *** water *** **
forest *** *** heloph *** ns
anthrop *** *** nymph ** ns
caudal seta length
pondtype eld forest anthrop mtype water heloph nymph
eld *** *** water ns ***
forest *** *** heloph ns ***
anthrop *** *** nymph *** ***

176 Basi´
nska et al.
Mean
Mean±SE
field forest anthrop
300
350
400
450
500
550
600
650
700
750
800
μm
Mean
Mean±SE
water heloph nymph
500
520
540
560
580
600
μm
AB
Figure 3. Filinia longiseta lateral setae length: (A) in different types of water bodies (as in gure 1) and (B) in various ecological
habitats (as in gure 2). Longitud de las setas laterales de Filinia longiseta: (A) en diferentes tipos de masas de agua (como en la
gura 1) y en diferentes habitats ecol´
ogicos (como en la gura 2).
irrespective of the examined station. The indi-
viduals of this species were signicantly larger
(F=52.3876, p<0.0001) in the anthropoge-
nically alerted ponds and in the mid-forest re-
servoirs, contrary to water bodies surrounded
by elds (Fig. 1, Table 3).
Comparing different types of habitat (irrespec-
tive of the type of pond) signicantly smaller spe-
ecimens of Filinia longiseta, in relation to the body
length, were noted among helophytes and the
open water zone contrary to stations located with-
in nymphaeids, where the largest individuals we-
re found (F=15.0725, p<0.01) (Fig. 2, Table 3).
No representatives of Filinia longiseta were found
in the samples collected from among elodeids.
Morphometric analysis of lateral setae lengths
also revealed variation in respect to different ty-
pes of water body (F=321.4887, p<0.01),
irrespective of habitat. The longest setae were re-
corded from specimens collected from forest re-
servoirs. The mean length values of lateral setae
were found in the anthropogenically inuenced
Mean
Mean±SE
field forest anthrop
220
240
260
280
300
320
340
360
380
400
μm
Mean
Mean±SE
water heloph nymph
230
240
250
260
270
280
290
300
310
320
330
μm
AB
Figure 4. Filinia longiseta caudal seta length: (A) in different types of water bodies (as in gure 1) and (B) in various ecological
habitats (as in gure 2). Longitud de la seta caudal de Filinia longiseta: (A) en diferentes tipos de masas de agua (como en la gura 1)
y en diferentes h´
abitats ecol´
ogicos (como en la gura 2).

Filinia longiseta body size in Wielkoposka ponds 177
water bodies and signicantly shorter setae of Fi-
linia longiseta were observed in the case of mid-
eld ponds (Fig. 3A, Table 3).
A comparison among different habitat types
(irrespective of the investigated types of ponds)
showed that signicantly shorter lateral setae of
this rotifer species were recorded from among
the open water contrary to the zones located
within helophytes and nymphaeides (F=8.1299,
p<0.01) (Fig. 3B, Table 3).
Biometric analysis of the length of the caudal
seta of Filinia longiseta also revealed statistically
signicant differences in respect to different ty-
pes of water bodies (F=57.78, p<0.0001). Si-
milar to results obtained from measuring the late-
ral setae length, the longest caudal seta was found
in the samples collected from forest ponds, whi-
le the shortest were obtained from the eld water
bodies (Fig. 4A, Table 3).
Analyses of caudal seta length of this species
inhabiting different kinds of habitats, irrespective
of the studied types of ponds revealed signicant
discrepancies (F=7.6843, p<0.01). The short-
est caudal setae of Filinia longiseta individuals
were noticed in the samples collected from nym-
phaeid stands and much longer setae were no-
ted in the stations located within the open water
zone and among helophytes (Fig. 4B, Table 3).
The concentration of total phosphorus, to-
tal nitrogen and chlorophyll differed bet-
ween the sampled stations (Table 2). The ma-
ximal content of phosphorus was observed
in pond 6 (TP = 1.41 mg L−1) and pond 14
(TP = 1.06 mg L−1), while the minimal concen-
tration was recorded from all stations within
pond 2 (TP = 0.01 to 0.02 mg L−1). Analyzing
the total nitrogen content from particular sta-
tions, a different pattern of minimal and ma-
ximal value distribution was observed com-
pared to total phosphorus concentration. The
highest total nitrogen concentration was found
in pond 1 (TN = 2.84 mg L−1) and pond 7
(TN = 2.10 mg L−1), while the lowest was found
in the case of pond 8 (TN = 1.06 mg L−1). The
largest differences were found between chlo-
rophyll acontent from among particular stations
in the examined ponds. The maximal value was
noted in pond 1 (363.6 mg L−1), while the mini-
mal was observed in pond 2 from among the open
water zone (0.001 mg L−1). In pond 5 the concen-
tration of chlorophyll was not analyzed.
DISCUSSION
The ecological requirements of Filinia longiseta
were conrmed in the present study, as the ma-
jority of sampled stations where it was found in
representative numbers were located within the
open water zone. Also the highest abundance of
this species was recorded from the pelagic area
of the anthropogenic pond without sh predation
present (pond 1). Filinia longiseta is equipped
with two long lateral setae which help the spe-
cies to jump rapidly backwards when threatened.
The lateral setae can be two to four times lon-
ger than the body size of this species (Nogrady,
1993), so a very dense stem structure of aqua-
tic plants can impede the movement of this ani-
mal. Therefore, in the collected material Filinia
longiseta avoided elodeids, which conrms both
its ecological requirements and the adaptations of
its morphological build to live in the open water.
However, in some cases (e.g. pond 2) an oppo-
site pattern of spatial distribution of Filinia indi-
viduals was observed with highest densities attri-
buted to littoral zone. High predation pressure in
this small water body is probably the reason for
obtaining such a discrepancy. Fish presence often
induces horizontal migrations of numerous spe-
cies of zooplankton towards aquatic plants stands
(e.g. Scheffer, 1998), where effective refuge con-
ditions for zooplankton can be found (Iglesias et
al., 2007). Similar results were obtained by Na-
rita et al. (1983) who found that in water bodies
located within areas where land is subject to hu-
man activity F. longiseta revealed higher abun-
dance among macrophyte stations.
There were six mid-forest ponds included in
this study and only in one of them did Fili-
nia longiseta occur in representative numbers
(pond 14) and only in low densities, which can
suggest that environmental conditions of this ty-
pe of water body are below optimal requirements
for the growth and development of F. longiseta.
Small mid-forest ponds are often overshaded and

178 Basi´
nska et al.
this can lead to a lowering of the water tempe-
rature. Filinia longiseta is described as warm-
stenotherm species, developing most abundant
communities at a temperature of between 23 and
31 ◦C (Nogrady, 1993), so its occurrence is typi-
cal for the summer period in freshwaters of the
temperate climatic zone (Duggan et al., 2001).
Ejsmont-Karabin and Kuczy´
nska-Kippen (2001),
who carried out research on urban ponds loca-
ted within the city of Pozna´
n, compared seaso-
nal changes in the composition and abundance of
rotifers and found that Filinia longiseta was re-
corded only from samples collected during the
summer season. Moreover, long-term data from
shallow eutrophic lakes (Andrew & Fitzsimons,
1992) have indicated that temperature changes
have an immediate and direct inuence on the
density and occurrence of rotifers, including F.
longiseta. The preference of Filinia longiseta to-
wards the pelagic zone and its association with
warm and unshaded water bodies was probably
the reason for the absence of this species in some
of the ponds as it occurred in only seven out of
the nineteen investigated water bodies and only
in ten out of thirty one studied stations.
Biometric analysis of specimens of Filinia
longiseta showed that both parameters included
in this study –the type of water body relating to
different land-use as well as microhabitat type–
signicantly inuenced Filinia longiseta size and
the length of its setae. Individuals of this species
were largest in ponds located within an anthro-
pogenically modied landscape (irrespective of
the type of habitat). This type of water body was
also characterized by the highest content of total
nitrogen and wide range of chlorophyll aconcen-
trations. Human activity in the catchment area of
a water body often inuences the enrichment of
the surface waters in nutrients which can positi-
vely correlate with the size structure of zooplank-
ton (Wang et al., 2007). This may have been a
reason for nding the largest individuals of this
rotifer in anthropogenically modied ponds. Fi-
linia longiseta, a typical eutrophic representati-
ve, which benet from a high biomass of phyto-
plankton, can successfully occur in water bodies
where blue-green algal blooms are present due to
the fact that it is not susceptible to bacterial toxins
(
Ceir¯
ans, 2007). The body dimensions of some
individuals in two ponds (pond 3 and pond 14)
may suggest coexistence Filinia longiseta longi-
seta with Filinia longiseta limnetica (Zacharias),
but these species occur in different environments.
Filinia longiseta limnetica is described as typical
for large and deep lakes, so its presence in plate
small water bodies is doubtful. Moreover, length
analysis was conducted on preserved material,
which may cause shrinking of the soft body. This
probably has an inuence on the proportion bet-
ween ratios lateral setae and body length because
spines are not changed by formalin. So any futu-
re research as regards the morphology of F. lon-
giseta should be carried out on live specimens.
The smallest specimens of Filinia longiseta were
found in the mid-eld ponds. As these ponds we-
re characterised by a wide range of nutrient con-
tent, as well as of chlorophyll aconcentrations,
it seems that food conditions may have been res-
ponsible for the occurrence of the smallest indivi-
duals with shorter spines here. This concurs with
the observation of Radwan et al. (2004), who sta-
ted that the body size and shape of many rotifer
specimens is determined directly by food availa-
bility. Filinia longiseta feeds mainly on detritus,
so the relationship with chlorophyll aconcentra-
tion should not be taken into consideration in this
study. The results obtained from Devetter (1998)
revealed that Filina longiseta was negatively co-
rrelated with the smallest fraction of phytoplank-
ton and also with predator species of Cyclops.
Filinia specimens with longer spines were attri-
buted to the forest ponds and also to anthropo-
genically changed water bodies, while the shor-
test spines were found in the mid-eld ponds.
Such a pattern of bristle length distribution may
suggest strong pressure of invertebrate predators
since the majority of these water bodies were
without sh. Individuals of Filinia longiseta are
consumed willingly by representatives of cope-
pods, which will often prefer this rotifer spe-
cies even to Keratella cochlearis (Williamson,
1987; Roche, 1990), which is believed to be the
most common freshwater metazoan in the world
(Lindstrom & Pejler, 1975; Koste et al., 1978)
and often occurs in great numbers in a variety
of water bodies (Kuczy´
nska-Kippen, 2007b;

Filinia longiseta body size in Wielkoposka ponds 179
Kuczy´
nska-Kippen, 2008). Furthermore, Filinia is
often preyed on by the second-instar of Chaoborus
(Moore, 1988) and also by predatory species of the
large rotifer Asplanchna, whose presence may in-
duce an increase in the length of the setae of F. lon-
giseta individuals (Garza-Mouri˜
no et al., 2005).
Comparing different types of habitat (irres-
pective of the investigated type of pond) dis-
crepancies were found concerning the length of
the rotifer body, lateral setae and caudal seta.
The shortest lateral setae were noticed among the
open water zone, contrary to two zones located
within the aquatic plants –helophytes and nym-
phaeides. This seems to be contrary to expecta-
tions, as the longest bristle as an adaptation to pe-
lagic life should be found in the open water area,
where sh predation is strongest during day and
rotifer appendages are usually longer as a mecha-
nism to reduce the effectiveness of a predator’s
attack (Lampert & Sommer, 2001).
ACKNOWLEDGEMENTS
This work was supported by the Polish Committee
for Scientific Research (KBN) under grant No.
2P06S 00829. The authors would also like to thank
B. Nagengast for identification of macrophyte
species in examined water bodies and M. Cichocka
for measuring zooplankton specimens.
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