Svetlana Davydova, Sergey Cherkashin · 142° 143° 144° 145° 48° 49° 50° 51° 52° 53° 54°...
Transcript of Svetlana Davydova, Sergey Cherkashin · 142° 143° 144° 145° 48° 49° 50° 51° 52° 53° 54°...
IchthyoplanktonIchthyoplankton as indicator of as indicator of the state of coastal ecosystems the state of coastal ecosystems
in the areas of oil and gas in the areas of oil and gas deposits on Sakhalin shelfdeposits on Sakhalin shelf
Svetlana DavydovaSvetlana Davydova, ,
Sergey Sergey CherkashinCherkashin
142° 143° 144° 145°48°
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75 76 7778
79 80 81 82
8384858687 88 89
909192939495
96
979899
100 101 102
c.Elizoveti
c.Terpeniya
c.Bellinsgauzena
c.Ratmanova
b.Lunskiy
b.Nabil
b.Chaivo
b. Pilvo
E
NOn the eastern shelf of the Sakhalin Island areas of investigation and extraction of hydrocarbonic raw materials coincide or adjoin with spawning and feeding grounds of fishes. Therefore scientists studying of fish’s biology and ecotoxicologicalconditions of coastal water are worried by this fact. Since 1999 searching works on the northeast shelf went to industrial stage of the Piltun-Astochsoyedeposit. In this connection estimation of the environmental condition and biota in the petroleum - gas deposit’s area on the eastern shelf of the Sakhalin Island were have been provided.
For report we used date collected in July of 2002 during scientific survey of TINRO-centre in the
area along the east coast the Sakhalin
Island bounded 48º00 N and 54º30 N. Eggs and larvae of fishes
were collected by the nekton net (d-0.80 m).
Dead eggs on I stage
Live eggs on I stage
Live eggs on III stage
Dead eggs on III stage
The total catch and number of eggs on the different stages of development of each species were calculated in samples, with dividing all eggs into “live” and “dead”. The main criterion of “dead” eggs is destruction of internal structure in account of breaking of yolk membranes and falling out of the yolk granules, turbidity of eggs membranes. The germinal disk or developing embryo is deformed and shifted off the normal position and clenched (on Dechnik, 1960).
Stages of development were determined according to
classification of Rass (1949)
T.chalcogramma 71%
Pl.asper 28%
eggs
Eggs and larvae of 16 species-representatives boreal ichthyofauna
presented ichthyoplanktoncommunity on the eastern shelf of
the Sakhalin Island. Eggs of walleye pollock Theragra chalcogramma and yellow-fin sole Pleuronectes asper
prevailed in catches.
142° 143° 144° 145°48°
49°
50°
51°
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456
7 8
9 10 11 12 13
1415 16 17
18
19 20 21 22 23
24252627 28
29 30 31 32
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3637
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40414243
44454647
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49 50 51
52
5354
5556
575859606162
6364656667
6869
70
7172
73
74
75 76 7778
79 80 81 82
8384858687 88 89
909192939495
96
979899
100 101 102
c.Elizoveti
c.Terpeniya
c.Bellinsgauzena
c.Ratmanova
b.Lunskiy
b.Nabil
b.Chaivo
b. Pilvo
E
N
High productive
area
low productive
area
On the basis of comparison of the currents speeds and duration of embryogenesis we concluded that the eggs of fishes caught during survey was spawned in the shelf water of the Sakhalin Island directly and more northern part of the Okhotsk Sea also. The drift of passive migrants along the east coast of the Sakhalin Island with gradual moving to open waters was confirmed by the spatial distribution of eggs and larvae practically all species.). The shelf northward of 51°00 N was high productive zone because it is widest and so actively used by fishes for reproduction, narrow shelf from 50°00 N to 51°00 N was low productive area.
0102030405060708090
100
shar
e of
live
egg
s
I II III IV
stages of development
Theragra chalcogramma
Pleuronectes asper
The minimal share of live eggs was market on first stage, maximum (practically 100%) - on forth stage . It is natural
phenomenon because during the embryo development one of the most sensitive to
influence of environmental factors is period from fertilization to beginning of
gastrulation that coincides with first stage of eggs according to Rass classification
(1946).
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18 61 62 85 87 59 94 76 60 27 86 81 93 88 17 80 15 21 16 77 92 89 82 84 71 29 20 28 19 63 44 51 14 46 5 47 4 56 49 26 54 58 83 6 8 55 64 22 3 43 13 48 78 1 57 52 53 45 25
stations
Shar
e od
nor
mal
dev
elop
med
eg
gs
T.chalcogramma%
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49 50 51
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5354
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6364656667
686970
71 72
73
74
7576 7778
7980 81 8283848586
8788 89
909192939495
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979899
100 101 102
less 10%
more 50%
Every catch of indicatorspecies was sorted to
increase of share of normally developing
eggs (without division on the different stages).
Then we separated stations where this
parameter was less than 10 % and called them -unfavorable stations
All data were put on the scheme of stations. Comparison of proportion eggs both species on the different stages along of shelf indicated that samples contained only 50 % (and less) live individuals were presented by eggs on first stages basically.
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18 60 80 95 61 76 59 93 86 77 87 75 62 79 17 88 64 14 84 63 94 16 89 81 73 56 66 57 55 78 58 82 49 13 11 71 67 12 70 65 69 68 10
s tations
Sha
re o
f nor
mal
dev
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men
t egg
sPl.as pe r
%
less 10%
more 50%
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9 10 11 12 13
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49 50 51
52
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575859606162
6364656667
686970
71 72
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74
7576 7778
7980 81 8283848586
8788 89
909192939495
96
979899
100 101 102
If high number of dead eggs in samples each species is consequence of influence a similar complex factors, areas with high rate of the dead eggs for both species should be coincide.
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29 30 31 32
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40414243
44454647
48
49 50 51
52
5354
5556
575859606162
6364656667
686970
71 72
73
74
7576 7778
7980 81 8283848586
8788 89
909192939495
96
979899
100 101 102
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1
23
456
7 8
9 10 11 12 13
14151617
18
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2425262728
29 30 31 32
33
34
35
3637
38
39
40414243
44454647
48
49 50 51
52
5354
5556
575859606162
6364656667
686970
71 7273
74
7576 7778
7980 81 8283848586
8788 89
909192939495
96
979899
100 101 102
2,8 % polloc
k
3,7 % flounde
r83%
Then unfavorable stations were marked by outline. This “anomalous zones” were compared for number identical stations. As a result, 83% number of anomaly stations
with share of dead eggs more 90% was similar for both species. Such high similarity of areas with high share of dead eggs yellow-fin sole and pollock can testify about common factors causing egg’s mortality. The share of normally developing eggs in “anomalous
zones” was 2,8 % (for pollock) and 3,7 % (for flounder), although for all water area this parameter was higher in 10 times. We marked that samples with maximum number of "dead" eggs of both species were coincided with oil and gas deposits on the north and
northeast shelf
natural deposit
In such zones hydrocarbons of
petroleum continuously penetrate into
water from deposits and
therefore their concentration in the deep layers
higher of natural background on 2-
3 orders.
Also on the shallow
zone some oil
hydrocarbons can be
accumulating in appear
layers of water.
Eggs and larvae
Inborn impurity of on the eastern shelf of the
Sakhalin Island determine relatively
high level of concentration of
metals in the different components of coastal
ecosystems. For example, the average
content of lead in surface water of
northern and central part of the eastern
shelf of the Sakhalin Island reached 2,7-3,3
mcg/l.
During well drilling every
stationary platform can
become source of regular multi
-component pollution. There
are produced waters,
components of drilling mud
including barite, mineral oil,
lubricating oils, heavy metals,
emulsifier, biocide and other toxic elements.
Though we analyzed data only Though we analyzed data only one year and received one year and received preliminary results but it is preliminary results but it is necessary to note that revealing necessary to note that revealing of areas with low share of of areas with low share of normally developing embryos at normally developing embryos at one or several species can be one or several species can be cause for regular ecological cause for regular ecological researches. researches.
Thank you !Thank you !