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Moshe Gophen Migal
(Corresponding
author)
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Galilee Technology Center P.O.
Box 831, Kiryat Shmone 11016, Israel
e-mail:
gophen@migal.org.il
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Publication Data
Paper received:
31
August 2009
Revised
received:
15
October 2009
Accepted:
24 January 2010
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Abstract
The impact of cladocerans
metabolic activities on the carbon (C), nitrogen (N) and phosphorus (P)
dynamics in Lake Kinneret (Israel) is
presented. The study, is based on the incorporation
of field data and experimental measurements. Grazing, respiration and
production rates of Diaphanosoma spp., Ceriodaphnia spp. and Bosmina spp. were experimentally measured? at three temperatures,? and the results were extrapolated to the
field biomass distribution at these respective temperatures, and the? total lake capacity was calculated using
the following equation: consumption = respiration + production? + excretion. The field capacity of
consumption, respiration and production were found to be mostly correlated
with biomass density, but the temporal fluctuation of? the percent of excretion from
consumed energy differed.? The increase
in P, decline in N and decrease in the TN/TP mass ratio in the epilimnion of Lake
Kinneret
during 1969-2004 created N limitation. An increase in C and decline in TN,
with a consequential increase in the C/TN ratio were documented. TP was
augmented but the C/TP ratio was only slightly increased.? During 1975-2004, P was probably, a minor
limitation for cladoceran growth. The positive
impact of recycled P by cladocerans under the N
limitation in Lake
Kinneret
is discussed. There is a current threat on the water quality, derived from N
limitation (mostly in summer-fall) and consequent Cyanophyta
blooms. Thus, the role of recycled P by grazers may be significant.
Key words
Cladocera, Nitrogen Limitation, Lake Kinneret
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