Global Change Abstracts The Swiss Contribution - SCNAT
Global Change Abstracts The Swiss Contribution - SCNAT
Global Change Abstracts The Swiss Contribution - SCNAT
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<strong>Global</strong> <strong>Change</strong> <strong>Abstracts</strong> – <strong>The</strong> <strong>Swiss</strong> <strong>Contribution</strong> | Oceans and Fresh Water Systems<br />
sociated earlier onset of stratification. According<br />
to our simulations a shift in the timing of phytoplankton<br />
growth resulting from a consistently<br />
warmer climate will exceed that resulting from a<br />
single unusually warm year. <strong>The</strong> numerical simulations<br />
are complemented by a statistical analysis<br />
of long-term data from Upper Lake Constance<br />
which demonstrates that oligotrophication has a<br />
negligible effect on the timing of phytoplankton<br />
growth in spring and that an early onset of the<br />
spring phytoplankton bloom is associated with<br />
high air temperatures and low wind speeds.<br />
<strong>Global</strong> <strong>Change</strong> Biology, 2007, V13, N9, SEP, pp<br />
1898-1909.<br />
08.1-268<br />
Water level fluctuations and dynamics of amphibious<br />
plants at Lake Constance: Long-term<br />
study and simulation<br />
Peintinger M, Prati D, Winkler E<br />
Germany, Switzerland<br />
Plant Sciences , Modelling , Limnology , Marine &<br />
Freshwater Biology<br />
Inundations of lakeshores are classical examples<br />
of how disturbance can influence community diversity<br />
and composition. As the occurrence and<br />
intensity of flooding are predicted to change dramatically<br />
as a result of climate change, predicting<br />
the consequences of such changes has become a<br />
major task for community ecology. Here we present<br />
abundance data of five species that comprise a<br />
species-poor community of high conservation value<br />
at lakeshores of Lake Constance over 17 years,<br />
during which one of the longest flood periods<br />
and the lowest water levels since 1890 occurred.<br />
We used simple regression models and increasingly<br />
sophisticated Markov chain models plus<br />
non-linear parameter estimation to put down<br />
abundance changes to direct effects of flooding<br />
on population-dynamic parameters and to indirect<br />
effects of flooding through modification of<br />
interspecific competition. We found a negative effect<br />
of flood duration on abundance changes for<br />
the non-specialist species Agrostis stolonifera and<br />
Phalaris arundinacea, but no effect on Carex acuta.<br />
<strong>The</strong> specialist species, Ranunculus reptans but<br />
not Littorella uniflora showed a positive effect of<br />
flooding. Data analysis revealed an unambiguous<br />
competitive hierarchy with the two graminoid<br />
species (C acuta, P. arundinacea) being superior,<br />
and the habitat specialists being most sensitive<br />
to interspecific competition. We used estimated<br />
parameters to project the community dynamics<br />
under different flooding regimes. Long-term projection<br />
showed that the original community is<br />
threatened by two non-specialist species (C acuta<br />
139<br />
and P. arundinacea). Even if this forecast was influenced<br />
by various model limitations, it may indicate<br />
irreversible changes in soil fertility during<br />
the phase of high eutrophication between 1950<br />
and 1980. Our study demonstrated that long-term<br />
abundance releves combined with Markov modelling<br />
and predictive simulations are an important<br />
counterpart to detailed short-term studies. <strong>The</strong><br />
combination of empirical and theoretical methods<br />
elucidates the interaction of biotic and abiotic<br />
factors in community change.<br />
Perspectives in Plant Ecology Evolution and Systematics,<br />
2007, V8, N4, pp 179-196.<br />
08.1-269<br />
Phytoplankton blooms in the Ross Sea, Antarctica:<br />
Interannual variability in magnitude,<br />
temporal patterns, and composition<br />
Peloquin J A, Smith W O Jr<br />
USA, Switzerland<br />
Oceanography , Marine & Freshwater Biology<br />
<strong>The</strong> continental shelf of the Ross Sea, Antarctica,<br />
is a unique region within the Southern Ocean.<br />
Phytoplankton growth is believed to be seasonally<br />
limited, first in austral spring by irradiance, and<br />
then in summer by biologically available iron. It<br />
also is historically known to have taxonomically<br />
distinct regimes: the south-central portion is<br />
dominated by Phaeocystis antarctica and to the<br />
west diatoms are abundant. We measured photochemical<br />
yield to interpret the health of the phytoplankton<br />
assemblage from 2001-2004 and interfaced<br />
these measurements with satellite remote<br />
sensing of pigments. <strong>The</strong> bloom of 2001-2002 was<br />
similar in both temporal and spatial distributions<br />
to the climatological mean of the Ross Sea, with a<br />
peak in biomass being observed in mid-December<br />
within the Ross Sea polynyas; F-v/F-m values averaged<br />
0.43. We found high (0.50-0.65) F-v/F-m for<br />
most of the seasonal phytoplankton bloom for<br />
2002-2003, suggesting that it was not seasonally<br />
iron limited. An unusual, large bloom occurred<br />
during 2003-2004, with an initial bloom of P. antarctica<br />
during austral spring followed by an extensive<br />
diatom bloom in summer that may have<br />
been enhanced by an intrusion of modified circumpolar<br />
deep water. On the basis of an analysis<br />
of the historical SeaWiFS records, accumulation<br />
of phytoplankton biomass in February may occur<br />
approximately every 2-4 years, potentially being<br />
a significant source of carbon on the continental<br />
shelf.<br />
Journal of Geophysical Research Oceans, 2007,<br />
V112, NC8, AUG 23 ARTN: C08013.