DISCUSSIONCladoceran species are ef

DISCUSSION
Cladoceran species are effective dispersers,
which can be important for restoring community
functioning after disturbances (Bonacina & Pasteris,
2001). The lakes investigated in the current
study are located at a distance of approximately
5 km from each other, and Lakes Liche´nskie and
´ Slesi´nskie are connected by a canal. Cladocerans
are known to actively disperse within a distance
of 100 km and are able to invade nearby lakes,
provided that biotic or abiotic factors do not
hinder their development (Shurin et al., 2000,
Shurin, 2000, Havel & Shurin, 2004). Therefore,
we assumed that there was a strong potential
for the exchange of cladoceran taxa between
the three study lakes. However, the composition
and biomass of cladocerans differed between the
three lakes. We suggest that the causes of these
differences are at least in partly related to the
different temperatures of the three lakes. Because
temperature can influence cladoceran community
structure either directly or indirectly, comparative
analysis of the biomass of cladoceran
species, population parameters, including fecundity,
death, and population growth rates, and food
conditions (phytoplankton) as well as contribution
analysis of top-down and bottom-up effects
(Polishchuk et al., 2012) can help to determine
the factors responsible for the observed cladoceran
community structure in the studied lakes.
In Lakes ´ Slesi´nskie and Liche´nskie, cladocerans
constituted approximately 60-80 % of the
total zooplankton biomass (Tunowski, 1994).
Total biomass is often related to the diversity of
zooplankton and cladocerans. When a greater
number of species are present, the biomass in
that communities tends to be higher as well.
Such positive relationships between diversity
and abundance have been well documented for
a variety of trophic groups (Cardinale et al.,