anglicky - Institute of Hydrobiology

studied with respect to season, density of large zooplankton, fish length, time of the day,
weather condition and solar radiation in Římov Reservoir, Czech Republic, using a bottommounted,
split-beam transducer (7 o , nominal angle; frequency 120 kHz), underwater camera,
gillnets and purse seine.
The proportion of sinusoidally swimming fish increased from April to August while this
behaviour was absent in October. The occurrence of sinusoidal swimming showed an
apparent pattern throughout the day; it increased sharply around sunrise, was highest within
5–6 hours around solar noon and sharply decreased around sunset. Significantly less frequent
occurrence of sinusoidal swimming was recorded during cloudy days compared to sunny
days. The vast majority of records came from fish of standard length ranging from 100 to 400
mm, which represents the typical size range of common bream Abramis brama and roach
Rutilus rutilus of age >1+, the main zooplanktivores in the reservoir. The presence of these
larger fish in the open water of the reservoir, as well as the presence of sinusoidal swimming,
apparently correlates with the presence of large zooplankton (Daphnia, Leptodora, Cyclops
vicinus) in the epilimnion. The increase of sinusoidal swimming between April, June and
finally August resulted in an increase of zooplankton component in fish guts. It appears that
high values of solar radiation, and stable calm weather during high pressure periods, result in
optimal optical conditions for sinusoidal swimming, making this foraging behaviour more
efficient and widely used in fishes exploiting the zooplankton production in the reservoir [2].
[1] Čech, M. and Kubečka, J. (2002). Sinusoidal cycling swimming pattern of reservoir fishes. Journal
of Fish Biology 61: 456–471.
[2] Jarolím, O., Kubečka, J., Čech, M., Vašek, M., Peterka, J. and Matěna, J. (2010). Sinusoidal
swimming in fishes: the role of season, density of large zooplankton, fish length, time of the day,
weather condition and solar radiation. Hydrobiologia 654: 253–265.
5.3 Anthropogenic nitrogen emissions during the Holocene and their possible effects on
remote ecosystems
J. Kopáček (jkopacek@hbu.cas.cz) and M. Posch (Coordination Centre for Effects, PBL,
Bilthoven, The Netherlands) reconstructed the emissions of reactive nitrogen (Nr = NH 3 –N +
NO x –N) from anthropogenic sources on a global scale since ~8000 BC, using a simple model
based on the development of human population and per capita factors of Nr emissions
originating from livestock production, biomass burning (biofuel use, forest and savannah
burning), and other anthropogenic sources (humans and pets, N-fertilizer use, fossil fuel
combustion) (Fig. 8).
The estimated global cumulative anthropogenic emissions of Nr to the atmosphere are
~17.4 Pg N (8.6 Pg NH 3 –N and 8.8 Pg NO x –N, respectively) for 8000 BC through the year
2000, with 28% of this amount emitted during 1850–2000, 42% during 1–1850, and 30%
during the previous 8,000 years. Forest and savannah burning represent the major cumulative
flux of both NH 3 –N and NO x –N (3.5 and 5.8 Pg, respectively). Livestock production and
biofuel burning are responsible for emissions of 3.3 and 1.2 Pg NH 3 –N, respectively, while
the application of synthetic fertilizers contributes 0.26 Pg NH 3 –N. The different duration of
biofuel and fossil fuel use (10,000 vs. ~150 years) causes the higher cumulative NO x –N
emissions from biofuel than fossil fuel use (1.9 vs. 1.1 Pg). The cumulative Nr emissions on a
land-area basis are 1.3 and 2.9 Mg N ha –1 globally and in Europe, respectively. Since an
estimated 60% of Nr emitted in Europe is also deposited there, the average cumulative
anthropogenic Nr deposition would be ~1.8 Mg N ha –1 , representing ~30% of the current N
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