Welcome to the 31st IUBS General Assembly and Conference on ...

Four seasons' <strong>the</strong>ory is set up. Four seasons' whole is put
forward here, having 4 seasons' organs <strong>and</strong> function.
Creatures are 4 seasons' whole. Life body is <strong>the</strong> unity of
state‐variation <strong>and</strong> state‐stability The Solar System is
bi‐four seasons' whole or life system, so are <strong>the</strong> galaxy
<strong>and</strong> society. There are 4 kinds of inorganic matter <strong>and</strong> 4
kinds of forces in <strong>the</strong> universe. And all inorganic matters
in <strong>the</strong> Solar System <strong>and</strong> <strong>the</strong> universe constitute inorganic
life body. The fundamental construction of life body is
bi‐four seasons' whole covering state‐varying
organization, state‐stabilizing organization <strong>and</strong> control
organization. Having state‐varying organization;
atmosphere, state‐stabilizingorganization; solid sphere
<strong>and</strong> control organization; hydrosphere, <strong>the</strong> earth is life
body. Creatures constantly occur in <strong>the</strong> 4 seasons'
movement of <strong>the</strong> Earth <strong>and</strong> <strong>the</strong> Solar System.
Variation in life­his<strong>to</strong>ry traits of
Daphniasimilis as a response <strong>to</strong> <strong>the</strong>
combined stresses of elevated ammonia <strong>and</strong>
hypoxia
Kai LV, Qianqian WANG, Rui CHEN <strong>and</strong>Zhou
YANG
Jiangsu Province Key Labora<strong>to</strong>ry for Biodiversity <strong>and</strong>
Biotechnology, School of Biological Sciences, Nanjing Normal
University, 1 Wenyuan Road, Nanjing 210046, China. Email:
yangzhou@njnu.edu.cn
Nuisance cyanobacterial blooms are distributed in lakes
<strong>and</strong> reservoirs around <strong>the</strong> world as a result of water‐body
eutrophication. The degradation of heavy blooms often
causes hypoxia <strong>and</strong> elevated concentrations of ammonia
in lakes, which can aggravate <strong>the</strong> adverse effect of blooms
on aquatic organisms. The aim of this study was <strong>to</strong> assess
<strong>the</strong> combined effects of elevated ammonia <strong>and</strong> hypoxia on
life‐his<strong>to</strong>ry traits ofa species of common cladoceran
Daphnia similis isolated in an eutrophicated lake which
regularly suffer from cyanobacterial blooms.
A 3×2 fac<strong>to</strong>rial design experiment was conducted with
animals exposed <strong>to</strong> combinations of three NH 3 ‐N levels (0,
0.300, 0.476 mg/L) <strong>and</strong> 2 dissolved oxygen levels
(normoxia: 8.0 mg/L<strong>and</strong> hypoxia:2.0 mg/L). Incubations
were 14 d <strong>and</strong> recorded <strong>the</strong> following life‐his<strong>to</strong>ry traits:
survival day; number of moults; time <strong>to</strong> first eggs; time <strong>to</strong>
first brood; size at first eggs; size at first brood; number
of offspring per brood; number of broods per female; <strong>and</strong>
<strong>to</strong>tal offspring per female.
Results showed: (1) hypoxia significantly decreased mean
survival day <strong>and</strong> number of moults, whereas ammonia
had no effect on <strong>the</strong> two traits. (2) The age at maturity
<strong>and</strong> reproduction is delayed by ammonia; <strong>the</strong> somatic
growth was seriously inhibited under high ammonia
levels <strong>and</strong> thus resulted in reproduction at a smaller body
size; whereas hypoxia marginally delayed <strong>the</strong> age <strong>and</strong> size
at maturation. (3) And both ammonia <strong>and</strong> hypoxia were
significantly detrimental <strong>to</strong> number of offspring per brood,
broods <strong>and</strong> <strong>to</strong>tal offspring per female; <strong>the</strong> interactive
effects of ammonia <strong>and</strong> hypoxia occurred for 4 traits:
mean survival day, time <strong>to</strong> first eggs, number of broods
<strong>and</strong> offspring per brood.
Our data clearly demonstrate that ammonia <strong>and</strong> hypoxia
are severely harmful <strong>to</strong> D. similis as ammonia <strong>and</strong>
hypoxia could contribute <strong>to</strong> enhanced mortality,
decreased moults, reduced growth, delayed maturation
<strong>and</strong> lower fecundity. The animals required more time <strong>to</strong>
reach maturation, which indicated phenotypic plasticity of
age <strong>and</strong> size at maturity in D. similis under ammonia
stress, i.e. age at maturity increases <strong>and</strong> size at maturity
decreases when <strong>the</strong> environment becomes less favourable.
Fur<strong>the</strong>rmore, interactive effect of ammonia <strong>and</strong> hypoxia
is a paramount consideration with relation <strong>to</strong> <strong>the</strong> <strong>to</strong>xicity
of ammonia <strong>to</strong> aquatic organisms. It is generally assumed
that Daphnia has a limited energy budget <strong>and</strong> that its
response <strong>to</strong> an environmental challenge will draw energy
away from normal development <strong>and</strong> reproduction. As <strong>the</strong>
clone of D. similis used in <strong>the</strong> experiments was isolated
from an eutrophicated lake which regularly suffer from
cyanobacterial blooms, our data can thus be used <strong>to</strong>
provide a ‘closer‐field scenario’ assessment of hypoxia
<strong>and</strong> elevated ammonia caused by degradation of
cyanobacterial blooms.
Wiley­Blackwell, John Wiley & Sons, Inc.
Carol BACCHUS <strong>and</strong> Judy PENG
Wilely Blackwell, John Wiley & Sons, Inc., Shanghai, China. Email:
cbacchus@wiley.com
Wiley‐Blackwell was formed in February 2007 as a result
of <strong>the</strong> acquisition of
Blackwell Publishing Ltd.
by John Wiley & Sons,
Inc., <strong>and</strong> its merger with
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