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°

49°

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54°

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6364656667

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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°

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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

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mal

dev

elop

med

eg

gs

T.chalcogramma%

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575859606162

6364656667

686970

71 72

73

74

7576 7778

7980 81 8283848586

8788 89

909192939495

96

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

elop

men

t egg

sPl.as pe r

%

less 10%

more 50%

142 143 144 14548

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44454647

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49 50 51

52

5354

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575859606162

6364656667

686970

71 72

73

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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40414243

44454647

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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

142 143 14448

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44454647

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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 !