spatio-temporal distribution of nekton community structure and … · 2020-04-30 · species number...
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Spatio-temporal distribution of nekton community structure and diversity change in Hangzhou Bay, CHINA
Reporter: Dongrong Zhang
Date: 05. 08. 2020
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CONTENTS
Subject background
Research object
Research results
Summary
01
02
03
04
Content
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Subject background
01 PART
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(1)Estuarine bay (complexity salinity, high turbidity and well-mixed ) is closely related to human life and
productive activities as a unique ecosystem (Barbier et al., 2011);
(2)Population dynamics and influence mechanism of nekton in the estuarine bay was seriously disturbed by
human activities;
(3)Estuarine bay waters serve as spawning, feeding and nursery grounds for fish larvae, juvenile and adult
nekton (Nyitrai et al., 2012).
Subject background
Hangzhou Bay
Typical area
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Research object
02 PART
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Research object
Estuarine nekton
Bait
Fo
od
org
an
ism
Rich sources of nutrients
Diverse habitats
High abundance and biomass of nekton
Complex spatial patterns of nekton
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Research results
03 PART
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Research results-1 Nekton assemblages and composition
Eco-group
Species number Mean Biomass Mean Abundance
Spring Summer Autumn Winter Spring Summer Autumn Winter Spring Summer Autumn Winter
Fish 20 15 21 16 108.52±67.68 41.04±27.00 90.99±104.07 136.61±215.36 8.10±11.51 10.61±6.22 13.83±8.35 4.03±3.29
Shrimp 8 11 7 5 8.38±6.68 39.93±26.77 35.48±24.06 2.64±2.27 17.30±14.19 55.12±36.01 80.58±67.27 5.03±3.29
Crab 3 5 5 4 14.55±9.38 2.33±2.77 9.54±10.56 3.93±3.75 2.21±1.85 0.42±0.36 1.55±1.43 0.18±0.11
Total 31 31 33 25 131.46±73.71 83.30±47.44 136.01±108.76 143.18±215.77 27.60±17.88 66.15±39.12 95.96±67.09 9.24±4.86
(1)57 taxa distributed among 23 families (2)Mean nekton biomass:Winter(fish)> Summer(shrimp) (3)Mean nekton abundance: Warm seasons(summer, autumn) >cold seasons (winter,spring) (4) Nekton of HZB were mainly composed of small near-shore species
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Research results-2 Spatial distribution of nekton community
Spatial distribution of nekton biomass (kg/km2) in HZB
Spatial distribution of nekton abundance (×103ind./km2) in HZB
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Research results-3 Dominant species of nekton
Dominant species (IRI>1000) :
Fish: Miichthys miiuy,
Collichthys lucidus ;
Shrimp: Exopalaemon
annandalei, Palaemon gravieri;
Crab : Portunus trituberculatus.
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Research results-4 Nekton species diversity
Spring Summer Autumn Winter
0
1
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a
a
a
Bio
mas
s div
ersi
ty i
nd
ex (
H')
One-way ANOVA test (a)
a
Spring Summer Autumn Winter
0.0
0.3
0.6
0.9
a
a
a
One-way ANOVA test
Bio
mas
s ev
enn
ess
ind
ex (
J')
(b)
a
Spring Summer Autumn Winter
0
1
2
3
aa
a
a
Non-parametric Kruskal-Wallis H test
Bio
mas
s ri
chn
ess
ind
ex (
d)
(c)
Spring Summer Autumn Winter
1
2
3 acbc
b
Abu
nd
ance
div
ersi
ty i
ndex
(H
')
(d)
a
Non-parametric Kruskal-Wallis H test
Spring Summer Autumn Winter
0.0
0.3
0.6
0.9 c
b
ab
Abu
nd
ance
ev
enn
ess
index
(J'
)
(e)Non-parametric Kruskal-Wallis H test
ac
Spring Summer Autumn Winter
0.0
0.4
0.8
1.2a
a
a
Abu
nd
ance
ric
hn
ess
index
(d
)
(f)One-way ANOVA test
a
0
50
100
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250
-80
-60
-40
-20
0
20
40
60
Spring Summer Autumn Winter
Alt
ernat
e in
dex
(A
I)
Mig
rate
ind
ex (
MI)
Migrate index
Alternate index
Diversity index (H'), evenness index (J') and richness index (d): (i) Warm seasons>cold seasons (biomass); (ii) Opposite result (abundance in H' and J')
AI : 94 to 218 MI :-73 to 35 Large variation and unstable
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Research results-5 Seasonal differences of nekton community structure
A01
A10
A02
A04
A07
A03
A08
A05
A06
A09
Sam
plin
g sites
50 60 70 80 90 100 Bray-Curtis similarity coefficient(%)
(a) Hierarchical cluster analysis of nekton biomass in spring
B08
B10
B09
B07
B04
B06
B05
B01
B02
B03
Sam
plin
g sites
40 60 80 100
Bray-Curtis similarity coefficient(%)
(b) Hierarchical cluster analysis of nekton biomass in summer
C10
C05
C07
C04
C06
C09
C08
C03
C01
C02
Sam
plin
g sites
50 60 70 80 90 100 Bray-Curtis similarity coefficient(%)
(c) Hierarchical cluster analysis of nekton biomass in autumn
D03
D01
D02
D10
D06
D08
D07
D09
D04
D05
Sam
plin
g sites
40 60 80 100 Bray-Curtis similarity coefficient(%)
(d) Hierarchical cluster analysis of nekton biomass in winter
(a) Spring : 3 groups(60%);
(b) Summer : 4 groups(65%);
(c) Autumn: 3 groups(65%);
(d) Winter: 3 groups(55%).
ANOSIM analysis results :
difference between seasons
reached the significance level
(Global R=0.616, P=0.0001)
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Research results-6 Relationship between nekton and environmental variables
Redundancy analysis (RDA): (a) negative correlated with salinity; (b) DO and surface salinity positive
correlated; negative correlated with DIP;
(c) Depth showed a significant positive correlation;
(d) Chla and surface temperature were highly positive correlated.
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Summary
04 PART
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Summary
The community of nekton in Hangzhou Bay showed significant spatio-temporal variation
With the index of H', J', d, AI, and MI , the community was not stable comfortably
The community of nekton could be divided into 3~4 groups in the 55%~65% similarity levels in four seasons
Physico-chemical factors were highly correlated with the nekton biomass
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Thank you for
your attention!