the state of benthos in the feeding grounds of gray whales filethe state of benthos in the feeding...

THE STATE OF BENTHOS IN THE FEEDING GROUNDS OF GRAY WHALES

(ESCHRICHTIUS ROBUSTUS)

OFF THE NORTHEAST COAST OF SAKHALIN IN 2016

Photo by Yuri Yakovlev

V.V. Ivin

Prepared for

Exxon Neftegas Limited

and

Sakhalin Energy Investment Company

VLADIVOSTOK

March 2017

WESTERN GRAY WHALE ADVISORY PANEL 18th meeting

WGWAP-18/17-EN 15-17 November 2017

PUBLIC

2

RUSSIAN ACADEMY OF SCIENCES FAR EAST BRANCH (DVO RAN)

Federally Funded Scientific Institution MARINE BIOLOGY NATIONAL RESEARCH CENTER

(NNTsMB DVO RAN)

APPROVED BY: Director, NNTsMB DVO RAN

__________________________ A.V. Adrianov

March , 2017

RESEARCH REPORT

ON THE STATE OF BENTHOS IN THE FEEDING GROUNDS OF GRAY WHALES

(ESCHRICHTIUS ROBUSTUS) OFF THE NORTHEAST COAST OF SAKHALIN IN

2016

Study Coordinator Candidate of Biological Sciences, Deputy Director, NNTsMB DVO RAN _________________ V.V. Ivin

Vladivostok 2017



PUBLIC

3

CONTENTS

INTRODUCTION.................................................................................................................................................................9

1. MATERIALS AND METHODS...................................................................................................................... 11

2. RESULTS AND DISCUSSION ....................................................................................................................... 12

2.1. BENTHOS DISTRIBUTION AND ABUNDANCE IN THE PILTUN AREA .................................................... 12

2.1.1. Total Benthos Biomass............................................................................................................................. 12

2.1.2. Biomass of Crustaceans (Crustacea) .................................................................................................. 14

2.1.3. Biomass of Isopods (Isopoda) ............................................................................................................... 15

2.1.4. Biomass of Amphipods (Amphipoda) ................................................................................................ 16

2.1.5. Year-To-Year Changes in Amphipod (Amphipoda) Biomass ................................................... 17

2.1.6. Biomass of Sand Lance (Ammodytes hexapterus) ......................................................................... 20

2.1.7. Composition and Distribution of Benthos Complexes ................................................................ 21

2.2. BENTHOS DISTRIBUTION AND ABUNDANCE IN THE CHAYVO SUBAREA .............................................. 23


2.3. BENTHOS DISTRIBUTION AND ABUNDANCE IN THE OFFSHORE AREA ................................................ 23


2.3.2. Biomass of Amphipods (Amphipoda) ................................................................................................ 24

2.3.3 Composition and Distribution of Benthos Complexes ................................................................ 25

2.4. DESCRIPTION OF WATER COLUMN AND BOTTOM SEDIMENTS .......................................................... 28

2.4.1. Water Temperature ................................................................................................................................... 28

2.4.2. Structure and Distribution of Bottom Sediments ......................................................................... 29

2.4.3. Organic Matter and Chlorophyll-a in Bottom Sediments ........................................................... 31

CONCLUSIONS ................................................................................................................................................................. 34

REFERENCES ................................................................................................................................................................... 38

APPENDIX .......................................................................................................................................................................... 43



PUBLIC

4

LIST OF FIGURES

Figure 1. Benthos sample collection stations grid in the study area ......................................... 11

Figure 2. A - Bottom grab sample with amphipods Monoporeia affinis (1), isopods Synidotea cinerea (2) and isopods Saduria entomon (3), collected in the Piltun area. B – Anomalous abundance of isopods Saduria entomon at station 3-1S .............. 15

Figure 3. Variations in total amphipod biomass (g/m2) in the Piltun area at depths of 11 - 15 m in 2002-2016. .......................................................................................................... 18

Figure 4. Variations in total amphipod biomass (g/m2) in the Piltun area as a function of sampling depth (using the example of 2003). .................................................................. 19

Figure 5. Variations in total amphipods biomass (g/m2) in the Offshore area in 2014-2016 as a function of sampling depth ............................................................................... 25

Figure A.1. Locations of sampling stations in the Piltun area. ................................................... 44

Figure A.2. Locations of sampling stations in the Chayvo subarea. ........................................... 47

Figure A.3. Locations of sampling stations in the Offshore area. ............................................... 48

Figure A.4. Average benthos biomass (g/m2) distribution in the Piltun and Chayvo areas in 2016. ................................................................................................................................ 50

Figure A.5. Average isopod biomass (g/m2) distribution in the Piltun and Chayvo areas in 2014-2016. ...................................................................................................................... 51

Figure A.6. Amphipod biomass (g/m2) distribution in the Piltun and Chayvo areas in 2014-2016. .......................................................................................................................... 52

Figure A.7. Distribution of temperature °С (A) and salinity ‰ (B) in the Piltun and Chayvo areas during the study period. .............................................................................. 53

Figure A.8. Distribution of biomass (g/m2) of sand lance Ammodytes hexapterus in the Piltun and Chayvo areas in 2014-2016. ............................................................................ 54

Figure A.9. Distribution of benthos complexes in the Piltun area ............................................. 55

Figure A.10. Distribution of average benthos biomass (g/m2)complexes in the Offshore area in 2016. ........................................................................................................................ 56

Figure A.11. Amphipod biomass (g/m2) distribution in the Offshore area in 2016. ............... 56

Figure A.12. Distribution of average benthos biomass (g/m2) complexes in the Offshore area based on long-term study data. Numbers of complexes are provided in the text. ....................................................................................................................................... 57



PUBLIC

5

LIST OF TABLES

Table 1. Benthos Biomass Distribution (g/m2) in the Piltun area ........................................... 13

Table 2. Taxonomic groups frequency of occurrence in the Piltun area ................................... 14

Table 3. Average Depth of Benthos Stations (± SE) Shown in Figure 3 ..................................... 20

Table 4. Composition of Benthos Complexes of the Piltun Area in 2016 .................................. 22

Table 5. Frequency of Occurrence of Taxonomic Groups of Benthos in the Chayvo Subarea ................................................................................................................................ 23

Table 6. Frequency of Occurrence of Taxonomic Groups of Benthos in the Offshore Area ..... 24

Table 7. Quantitative characteristics (biomass, g/m2) of benthos complexes in the Offshore area ....................................................................................................................... 27

Table 9. Near-bottom water temperatures (°С) in 2012-2016 in the Coastal and the Offshore feeding areas. ....................................................................................................... 28

Table 10. Characteristics of sediment groups in the Coastal and Offshore areas .................... 30

Table A.1. List of stations in the Piltun area used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel ......................................... 45

Table A.2. List of stations in the Chayvo subarea used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel ................................... 47

Table A.3. List of stations in the Offshore area used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel ......................................... 49



PUBLIC

6

SUMMARY

Report, 57 pp, 5 figures, 10 tables, 42 references, appendix.

RESEARCH REPORT ON THE STATE OF BENTHOS IN THE FEEDING GROUNDS OF GRAY

WHALES (ESCHRICHTIUS ROBUSTUS) OFF THE NORTHEAST COAST OF SAKHALIN IN 2016

FORAGE BENTHOS, BIOCOENOTIC COMPLEXES, GRAY WHALES, ESCHRICHTIUS

ROBUSTUS, NORTHEAST SAKHALIN, BOTTOM SEDIMENTS

The purpose of the research was to study the distribution and status of benthos in the

Piltun/Chayvo and Offshore feeding areas by collecting samples based on a standard grid of

survey stations in order to deepen our knowledge of the distribution of gray whales and their

movements in relation to forage targets.

The following primary objectives of the Research Program on Gray Whale Forage

Benthos in 2016 off the Northeast Coast of Sakhalin were achieved:

1. Determination of the distribution and quantitative characteristics of benthos of

individual taxonomic groups and dominant species;

2. Comparison of forage biomass and distribution in the Piltun/Chayvo and Offshore

feeding areas to 2002-2015 data to provide the historical background of the

conditions relative to the forage resources in 2016;

3. Determination of yearly variability of the abundance of benthos in the study areas;

4. Determination of the structure and distribution of bottom sediments;

5. Assessment of the effect of hydrological conditions and the particle size distribution

of bottom sediments on the distribution and abundance of benthos;

6. Determination of the organic carbon and chlorophyll-a concentrations in bottom

sediments as measures of productive activity of the study areas.

The study methods included: 1) analysis of data on the quantitative characteristics of

macrobenthos and its distribution in the Coastal (Piltun/Chayvo) and Offshore feeding areas

obtained in the course of field surveys aboard the Pavel Gordienko Research Vessel during the

period from October 3 through October 26, 2016; 2) comparison of the results obtained to

2002-2015 data to provide the historical background of the conditions relative to the forage

resources in 2016; 3) assessment of environmental parameters (water temperature, structure

and distribution of bottom sediments, concentrations of organic matter and chlorophyll-a in

bottom sediments) to provide conditions for the existence of macrobenthos in the study area.



PUBLIC

7

The report includes an introduction, a description of materials and methods, three

sections devoted to analysis of the distribution and abundance of benthos in each of three study

areas (Piltun, Chayvo, and Offshore), a section devoted to a description of the water column

and bottom sediments, conclusions, a list of references, and an appendix.

The research showed that the average benthos biomass in the Piltun feeding area in

2016 did not differ substantially from historical levels. As in previous years, the common sand

dollar Echinarachnius parma accounts for most of the total benthos biomass for the area as a

whole, with biomass levels that can exceed 99% at depths greater than 20 m. The biomass

distribution of amphipods, the basic component of gray whale forage benthos along the coast

in the Piltun feeding area in 2002-2016, has similar trends: areas with the highest biomass are

associated with the shallow coastal sections of the water area.

A lagoonside complex of amphipod species was identified within the Piltun feeding area

and was prevalent in the southern and central parts of the area, primarily at depths less than

15 m in а zone of fine sands, where demineralized and warmed water enriched with nutrients

flows in constantly from the lagoons. The mixohaline species Monoporeia affinis is dominant in

regard to abundance. The contribution of this species to total amphipod biomass decreases

sharply with depth, even within the complex. Another species which is significant in regard to

biomass in this complex is the polyeuhaline species Eogammarus schmidti. The types of bottom

sediments and the dominant amphipod species change with the depth.

Analysis of the long-term patterns of amphipod abundance in the Piltun feeding area

shows a sudden decrease in amphipod biomass starting in 2013 compared to previous years,

which may be possibly explained by a sharp decrease in salinity due to heavy discharge from

the Amur River during the catastrophic 2013 floods, or by their being consumed by the steadily

growing gray whale population in the operations area.

In addition to the decrease in amphipod biomass in the Piltun feeding area, the

continuous growth since 2015 of aggregations of another forage target, a benthic fish – the

Pacific sand lance Ammodytes hexapterus, stands out.

The maximum biomass of the amphipod Ampelisca eschrichti, the basic component of

forage benthos for gray whales in the Offshore feeding area, amounted to 1072 g/m2 in 2016,

which matches the levels for all previous years of observations. These levels are comparable or

even, and in most cases, exceed the similar benthos parameters in other highly productive

regions of North Pacific. The average biomass levels of forage benthos within the Offshore area

have been stable in 2002-2016, with no substantial year-to-year variations.



PUBLIC

8

Analysis of characteristics of the water column and bottom sediments in 2016 revealed

no substantial deviations from the parameters recorded during previous study years.

The 2016 research program generally is complete. The data obtained will make it

possible in the future to assess spatial and temporal changes in benthic communities in the

study area under the effects of global climate changes and other environmental changes.



PUBLIC

9

INTRODUCTION

Studies of benthic communities over the entire feeding period are essential for

understanding the forage ecology of the western gray whales, including changes in their

distribution and behavior. On the other hand, the information about temporal and spatial

changes in the prey of gray whales allows to define adequate measures to conserve the group

of gray whales near the North-East coast of Sakhalin Island and to protect their ecosystem. The

set of operations to study the forage benthos and gray whale feeding environments, whose

results are provided in this report, was conducted in October of 2016 in accordance with the

2016 Program for Gray Whale Monitoring Offshore Northeast Sakhalin Island developed by

Exxon Neftegas Limited (ENL) and Sakhalin Energy Investment Company, Ltd. (Sakhalin

Energy) and duly approved by a federal executive body, the Russian Federation Ministry of

Natural Resources and Environment (Minprirody of Russia), by the Federal Service for Nature

Use Oversight (Rosprirodnadzor, and the Federal Fisheries Agency (Rosrybolovstvo) in

accordance with the established procedure.

Benthos studies offshore Sakhalin Island have been conducted annually since 2001. The

research has been focused on historical gray whale feeding areas, such as the Piltun area

located seaward of Piltun Lagoon, the Intermediate area south of the Piltun sampling grid,

including the coastal Chayvo area, as well as the Offshore feeding area and certain feeding

locations. To date, the benthic studies have resulted in an extensive dataset of the distribution,

abundance and temporal-spatial dynamic of gray whale food resources.

The main task of this work has been to study the distribution and status of benthos along

the grid in the Piltun/Chayvo and Offshore feeding areas, by taking samples from the array of

station in order to increase our understanding of gray whale distribution and movement in

relation to prey availability. Main objectives of these studies are as follows:

1. Determine benthic species distribution and measurements of the most common

benthic species and its major taxonomic groups;

2. Compare forage biomass and distribution in the Piltun/Chayvo and Offshore feeding

areas to 2002-2015 data to provide the historical background to food resources in

2016;

3. Determine annual variability in benthos distribution and abundance within the

areas of the studies;

4. Determine the structure and distribution of bottom sediment;



PUBLIC

10

5. Assess the effects of hydrological conditions and the particle size distribution of

bottom sediments on the distribution and abundance of benthos;

6. Determine the concentrations of organic carbon and chlorophyll-a in bottom

sediments as measures of productive activity in the study areas.



PUBLIC

11

1. MATERIALS AND METHODS

Studies were conducted in three polygon-shaped areas offshore northeastern Sakhalin

Island (Fig. 1) from October 3 through October 26, 2016, using the Pavel Gordienko Research

Vessel according to the research program.

Figure 1. Benthos sample collection stations grid in the study area



PUBLIC

12

The scope of the studies included repeated sampling using the large survey grid from

past years covering the Piltun/Chayvo and Offshore feeding areas. In addition to benthos

samples, samples of bottom sediments were collected to determine the particle size

distribution and organic carbon and chlorophyll-a concentrations.

Benthos samples were collected at stations in the Piltun area positioned in a water

depth range of 7.8 - 33.6 m. The layout of the stations and the station coordinates are presented

in the Attachment (Fig. A.1 and Table A.1). The sampling grid includes 45 stations, although at

two stations (44M, 45M) the collection of bottom grab samples was not completed due to the

nature of the soil (coarse gravel), which is unsuitable for Van-Veen grab samplers.

Samples were collected at 8 stations in the Chayvo area in a depth range of 9.9 – 12.4 m.

The layout of the stations and the station coordinates are presented in the Appendix (Fig. A.2

and Table A.2).

Samples were collected at 34 stations in the Offshore Area in a depth range of 22.2 to

61.8 m. The layout of the stations and the station coordinates are presented in the Appendix

(Fig. A.3 and Table A.3).

Study methods used in 2016 have been described in detail by Fadeev (2013a).

2. RESULTS AND DISCUSSION

2.1. Benthos Distribution and Abundance in the Piltun Area

2.1.1. Total Benthos Biomass

The average benthos biomass in the Piltun area in 2016 ranged from 27.6 g/m2 (st. 1-

3S, depth 12.2 m) to values above 4000 g/m2 (st. 4-3S, 26.5 m) (Fig. A.4), averaging 621.1 ±

133.7 g/m2 (n=43). For comparison, in 2015 the level was 571.4 ± 119.2 g/m2 (n=55), in 2014

it was 599.8±151.5 g/m2 (n=56), and in 2013 it was 614.1±132.2 g/m2 (n=58) (see Table 1).

Year-to-year variations in biomass are not statistically significant (t-test, p>0.05).



PUBLIC

13

Table 1. Benthos Biomass Distribution (g/m2) in the Piltun area

Taxon

Depth

Total Area

>10-15 m 16-20 m 21-25 m 26-35 m

2016 2015 2014 2016 2015 2014 2016 2015 2014 2016 2015 2014 2016 2015 2014

Amphipoda 18.1 22.2 21.3 20.7 6.3 24.4 2.5 3.2 3.2 3.8 6.1 12.4 11.1±2.6 14.1±2.5 16.1±3.3

Isopoda 1.6 5.3 5.1 62.0 7.2 17.8 2.7 6.5 8.8 4.0 0.0 1.4 9.5±6.4 4.5±0.8 7.1±1.7

Bivalvia 29.2 50.9 43.9 97.5 57.0 39.4 106.2 118.0 65.3 38.5 60.3 78.5 60.6±11.8 65.6±13.2 55.0±11.8

Cumacea 0.5 0.5 0.2 0.3 0.1 0.0 0.1 0.0 0.1 0.2 0.2 0.1 0.3±0.1 0.3±0.1 0.2±0.1

Echinoidea 10.7 4.9 7.6 497.7 609.6 552.2 898.6 1095.2 1033.3 877.1 862.6 899.3 496.4±129.7 434.2±120.

2 497.2±153.0

Polychaeta 4.1 2.9 3.6 13.8 13.7 25.1 10.5 6.9 15.5 10.4 21.7 9.8 8.3±1.4 8.5±2.1 10.8±3.4

Other 4.4 35.2 2.4 100.8 15.7 8.1 65.1 44.5 11.6 16.2 75.2 40.9 35±10.5 44.2±13.7 13.4±2.6

Total 68.5 121.9 84.2 792.8 709.6 667.0 1085.8 1274.3 1137.9 950.1 1026.1 1042.6 621.1±133.7 571.4±119.

2 599.8±151.5



PUBLIC

14

In 2016, as in previous years, most of the area’s total benthos biomass (an average of

more than 79%) is made up of sand dollars (Echinarachnius parma), and at depths over 20 m

the percentage of sand dollars can exceed 90%.

A total of 17 taxonomic benthos groups differing substantially in frequency of

occurrence (as percentages of the total number of stations) were recorded in the Piltun area

(Table 2).

In 2016, as in previous years, most of the benthos biomass in the waters throughout

the Piltun area was made up of groups with a frequency of occurrence higher than 50%:

amphipods, polychaetes, cumaceans, bivalve mollusks, isopods, sand dollars and fishes. For

the Piltun area as a whole, these 7 taxonomic groups define more than 99% of the average

total benthos biomass.

Table 2. Taxonomic groups frequency of occurrence in the Piltun area

Taxonomic groups frequency of occurrence (Р, %), n=43 P >50 % P = 25-50 % P = 10-25 % P<10 %

Group Р, % Group Р, % Group Р, % Group Р, % Amphipoda 100.0 Mysidae 37.2 Aсtinia 9.3 Polychaeta 100.0 Gastropoda 25.6 Decapoda 7.0 Cumacea 93.0 Nemertini 25.6 Cirripedia 4.7 Bivalvia 90.7 Hydrozoa 4.7 Isopoda 74.4 Sipunculida 4.7 Echinoidea 69.8 Ascidia 2.3 Pisces 62.8 Holoturia 2.3

2.1.2. Biomass of Crustaceans (Crustacea)

Crustaceans (amphipods and isopods) are the most important food resource for gray

whales (Fig. 2). The main crustacean groups had high frequencies of occurrence in 2016,

with amphipods occurring in 100% of samples, and isopods in > 74% (Table 2); these

frequencies were not substantially different from earlier data. Based on the 2016 data, the

overall share of crustaceans in the macrobenthos biomass in the Piltun Bay area was 70.9%

at depths less than 11 m; 28.8% in the depth range of 11-15 m; and only 0.8% at depths

greater than 25 m.



PUBLIC

15

A

B

Figure 2. A - Bottom grab sample with amphipods Monoporeia affinis (1), isopods Synidotea cinerea (2) and isopods Saduria entomon (3), collected in the Piltun area.

B – Anomalous abundance of isopods Saduria entomon at station 3-1S

2.1.3. Biomass of Isopods (Isopoda)

Isopod biomass in the Piltun feeding area in 2016 (Fig. A.5) ranged from 0 to 274.4

g/m2 (st. 3-1S, depth 20.5 m) and averaged 9.5±6.4 g/m2, which is higher than the levels of

past years (see Table 1). The spatial distribution of isopods is a distinctly mosaic distribution.

In 2016, as in previous years, the most significant isopod aggregations were in the southern

part of the area (Fig A.5). The small isopod, Synidotea cinerea (average body weight 0.02 g;



PUBLIC

16

Fig. 2A), was a significant component of isopod biomass in the Piltun area. In 2016, this

isopod had a significant frequency of occurrence (> 50%) in the study areas.

Patches with elevated crustacean biomass (> 20 g/m2) at depths greater than 20 m

were formed by the large isopod Saduria entomon – one of the important components of the

food resources for the gray whale. These large isopods (body weight up to 5 g, average

weight 2.1 g; Fig. 2A-B) are encountered much less frequently in the Piltun area and in

deeper waters. However, this species can form large local accumulations that make it

possible to consider S. entomon, together with other crustaceans, as potential prey for gray

whales. In contrast to S. cinerea, the biomass of S. entomon increases with depth. 2016 was

characterized by an anomalous abundance of Saduria entomon isopods at station 3-1S with

an average biomass of 274.4 ± 16.0 g/m2 (Fig. 2B).

Excluding the anomalous levels recorded at station 3-1S, the average biomass of

isopods varied from 0 to 36.1 g/m2, and averaged 3.14 ± 1.1 g/m2 (n=43). That is somewhat

below the previous years' levels (Table 1); however, the year-to-year biomass variations do

not demonstrate any statistically significant variations (t-test, p>0.05) vs. 2013-15 data.

2.1.4. Biomass of Amphipods (Amphipoda)

In 2016, the average amphipod biomass in the Piltun area (Fig. A.6) ranged from 0.07

(st. 3-4S, depth 24.2 m) to 81.8 g/m2 (st. 2-4N, depth 20.7 m) and averaged 11.1±2.6 g/m2

(n=43), which is somewhat below the level levels of previous years. For comparison, in 2015

this parameter had a value of 14.1±2.5 g/m2 (n=55); in 2014 it was 16.13±3.29 g/m2 (n=56).

Year-to-year variations of biomass distribution are not statistically significant (t-test,

p>0.05), as shown in Fig. A.6. The main portion of the total amphipod biomass (from 47% to

89%) is Monoporeia affinis (Fig. 2).

In 2016, aggregations of amphipods with average biomass exceeding 40 g/m2 were

localized haphazardly in different parts of the Piltun area, in the coastal zone near the 10-m

isobath, in the area of fine sands. The areas with the highest biomass in 2016 were associated

both with the southern part of the area (the mouth of Piltun Bay) and with the seaward zone

in the northern part of the area. Water salinity and temperature distribution maps (Fig. A.7)

for the coastal zones of the study area show distinct local areas with seawater which is

warmer and has lower salinity. The presence of water masses with different thermohaline

characteristics apparently has a significant effect on the spatial distribution and “sizes” of

amphipod aggregations in the Piltun area.



PUBLIC

17

The lagoonside complex of amphipod species is spread over the south and central

part of the Piltun area mainly in depths less than 15 m, in the zone of fine sands where the

desalted, warmed, and biogen-enriched waters of the transformed inflow of Amur River

come in. The area is dominated by the brackish-water (mixohaline) Monoporeia affinis

species. M. affinis is a burrowing detritus eater. The contribution of this species into the total

amphipod biomass is dramatically reduced with depth (Table 1). The second important

species in this complex in terms of biomass is the polyeuhaline Eogammarus schmidti. Types

of bottom sediments and mass amphipod species change along with depth (Ivin and

Demchenko, 2014).

The significant impact of natural factors on benthic life explains this phenomenon. It

is well known that in the Coastal area at the depth of 10–20 m a seasonal thermocline is

formed, which boundaries can shift under the effect of wind upwellings and downwellings

(Krasavtsev et al., 2000; Rutenko et al., 2009; Rutenko, Sosnin, 2014). Also, a water stream

is known at the northeast coast of Sakhalin Island, that is distinctively distinguished by lower

salinity and flows with the speed of 7–9 cm/s achieving the Nabil Bay (Pishchalnik,

Arkhipkin, 1999).

2.1.5. Year-To-Year Changes in Amphipod (Amphipoda) Biomass

The data used for analysis of year-to-year changes in amphipod biomass traditionally

(see Fadeev, 2013b) consisted of the data collected in 2002-2016 from all grid and feeding

point stations located in the Piltun feeding area. These stations represent a subset of the

entire set of grid stations and are located in the Piltun coastal area at depths of up to 15 m,

i.e. depths of maximum amphipod concentration. Since the greatest number of samples for

the entire survey period were made at depths of 11 to 15 m, we limited the analysis data file

to data from that depth range.

Figure 3 shows differences in the average total amphipod biomass. Based on the

figure, traditionally it is assumed (see Fadeev, 2013b) that the amphipod biomass decreases

from its maximum values in 2002 (115.5±19.6 g/m2) and in 2004 (104.0 ± 21.1 g/m2) to

minimum values in 2009 (23.5 ± 4.3 g/m2). The average amphipod biomass in the coastal

zone of the Piltun area was 60-65 g/m2 from 2005 through 2008, in 2010, and 2012.



PUBLIC

18

Figure 3. Variations in total amphipod biomass (g/m2) in the Piltun area at depths of 11 - 15 m in 2002-2016.

Significant fluctuations in amphipod abundance throughout the survey period can be

due to both changes in hydrological conditions and year-to-year and seasonal dynamics of

crustaceans. The main variables are:

• time and season of sampling;

• minimum and maximum depths of sampling;

• number of stations located at minimum and maximum depths;

• vertical, seasonal, and daily migrations of amphipods;

• aggregated distribution of amphipods and high variations of their quantities and

sizes from station to station;

• localization and sizes of aggregations depending of hydrological conditions;

• life cycle of mass amphipod species (for example, in spring or in early summer the

natural selective elimination of full-grown females takes place after the breeding

period, and in late autumn males die after the copulation).

During previous studies (Ivin and Demchenko, 2014), we attempted to explain the

year-to-year variations in amphipod abundance by methodological causes related to the

prevalence of different sampling depth ranges in different years. It is well known (Fadeev,



PUBLIC

19

2002-2013; Fadeev, 2003-2012) that the quantitative abundance of amphipods in the Piltun

area decreases significantly with depth (Fig. 4).

Figure 4. Variations in total amphipod biomass (g/m2) in the Piltun area as a function of sampling depth (using the example of 2003).

It is quite clearly seen from the presented graph that maximum abundance of

amphipods is observed at depths less than 15 m. Over fine sands there, the saltwater

amphipod complex with prevalent M. affinis of species) is dominant. At depths over 20 m, in

gravel-sand soils increased biomasses are formed by other amphipod species from the

marine complex, primarily Anisogammarus pugettensis and Anonyx nugax. Probably, the

grain size composition of soils, the salinity, and the temperature control the distribution of

the saltwater and the marine amphipod complexes in the Piltun area.

Meanwhile, analysis of the depths at which the data shown in Figure 3 (Table 3) were

collected did not consider methodological errors and did not make it possible to explain the

year-to-year variations in the abundance of amphipods by methodological causes. This

omission, in turn, indicates both the need to be very careful in interpreting of obtained

results and the need for thorough planning of field research.



PUBLIC

20

Table 3. Average Depth of Benthos Stations (± SE) Shown in Figure 3

Year Average depth (m) Year Average depth (m) 2002 13.3 ± 1.4

2010 13.2 ± 1.0

2003 13.1 ± 0.9

2011 13.4 ± 1.4 2004 14.0 ± 1.3

2012 12.9 ± 1.3

2005 13.8 ± 1.3

2013 13.2 ± 1.0 2006 14.2 ± 1.0

2014 12.5 ± 1.2

2007 13.4 ± 1.0

2015 12.6 ± 0.7 2008 13.7 ± 1.0

2016 13.1 ± 0.4

2009 13.3 ± 0.9

Since the distribution of amphipods in the study area is controlled by many factors,

the sharp drop in amphipod biomass in 2013-2016 may be possibly explained by a sharp

decrease in salinity as a result of heavy discharge from the Amur River from catastrophic

flooding in 2013, or by their consumption by the steadily growing gray whale population in

the operations area.

2.1.6. Biomass of Sand Lance (Ammodytes hexapterus)

The biomass of the sand lance Ammodytes hexapterus in the Piltun area in 2016 (Fig.

A.8) ranged from 0 to 323.2 g/m2 (st. 4-1S, depth. 18.4 m) and averaged 32.8 ± 10.5 g/m2 at

a frequency of occurrence throughout the study area >63 % (n=43), which exceeds the

values of previous years. For comparison, in 2015, the average biomass of the species

amounted to 27.1 ± 5.2 g/m2 (n=55); while in 2014 it was 5.35±1.51 g/m2 (n=56), and in

2013 it was 7.04±1.49 g/m2 (n=58). The most dense aggregations of the species were

recorded in the central and southern part of the study area (Fig. A.8) in areas with sandy

bottoms and mixed gravel.

Results of the previous research work (Fadeev, 2013b) show significant year-to-year

variations of the sand lance (A. hexapterus) abundance and its frequency of occurrence (the

percentage of samples where sand lance occurred) in the Piltun area.

In 2002-2003, the frequency of occurrence of sand lance A. hexapterus (percentage of

samples containing sand lance) in samples from the Piltun area was 5–8%, with an average

biomass of 4.6–6.2 g/m2. The frequency of occurrence of sand lance in 2004 was higher

(15%), with an average biomass of 14.8±4.8 g/m2. Within local accumulations the sand lance

biomass varied from 68 to 166 g/m2, which amounted to 25% – 48% of the total

macrobenthos biomass in the samples.

Sand lance was encountered in small numbers throughout the Piltun area in 2004-

2005, with the densest accumulations recorded in the northern and middle parts of the area.



PUBLIC

21

In 2005, when frequency of occurrence was 15% throughout the area, the frequency in the

northern part was as high as 40–60%. Average biomass was 16.3±4.4 g/m2 for the entire

Piltun area and reached 150–236 g/m2 within local accumulations.

Average biomass of sand lance in the Piltun area in 2008 and 2009 (8.8±3.7 g/m² and

12.9±5.4 g/m²) was lower than in 2007 (27.7±12.1 g/m²). At the same time a considerable

lowering of sand lance occurrence frequency in the northern part of the Piltun area was

observed: from 40–60% in 2005 to 20–25% in 2006-2007, and 8–12% in 2008-2010. The

causes of this lowering are unknown, perhaps it is connected with the beginning of natural

lowering of sand lance abundance. In 2010, the frequency of occurrence of sand lance in the

northern part of the area increased to 20%. In 2010, two gray whale feeding points with sand

lance biomass levels of 66 and 78 g/m2 were observed.

The significant increase in sand lance biomass observed in the Piltun area since 2015

compared to previous years makes it possible to hope for an increase in the stocks of this

forage species.

2.1.7. Composition and Distribution of Benthos Complexes

Three benthos complexes (Fadeev, 2002-2013; Fadeev, 2003-2012) were identified

in the Piltun area based on previous studies: the Amphipoda complex, the Bivalvia complex,

and the complex of sand dollar E. parma (Fig. A.9). The identified benthos complexes differ

in both composition and quantitative abundance of the taxonomic groups (Table 4).

The Amphipoda complex occurred at 13 stations at depths ranging from 7.9 to 33.4 m

(average depth 15.1 m) in the fine- and medium-grained sand zone. The complex is

distributed in a belt-like pattern along the coast in the Piltun area (Fig. A.9). Average biomass

of the complex (52.8±5.2 g/m2) is made up primarily of amphipods (45.5%) and bivalve

mollusks (28.2%); the contribution of polychaetes (12.4%) is somewhat lower.



PUBLIC

22

Table 4. Composition of Benthos Complexes of the Piltun Area in 2016

Taxonomic group

Complex Amphipoda

Complex Bivalvia

Complex E. parma

B (g/m2) B (g/m2) B (g/m2)

Amphipoda 24.0 ± 4.3.. 10.6 ± 7.3.. 2.3 ± 0.6.. Bivalvia 14.9 ± 3.4.. 66.9 ± 9.8.. 98.5 ± 25.7.. Cumacea 0.5 ± 0.2.. 0.4 ± 0.1.. 0.1 ± 0.0.. Decapoda 0.3 ± 0.3.. 0.2 ± 0.2.. 0.0 ± 0.0.. Echinoidea 0.8 ± 0.8.. 55.4 ± 20.1.. 1217.7 ± 240.1.. Isopoda 1.8 ± 0.5.. 27.0 ± 24.8.. 5.1 ± 2.4.. Pisces 3.3 ± 2.0.. 2.0 ± 1.1.. 76.9 ± 23.0.. Polychaeta 6.5 ± 2.2.. 12.1 ± 4.5.. 7.7 ± 1.0.. Total 52.8 ± 5.2.. 178.9 ± 39.1. 1410.3 ± 230.7..

The Bivalvia complex occurred at 11 stations at depths ranging from 12.1 to 29.8 m

(average depth is 18.4 m) in fine sands and mixed gravel and sand bottoms. In contrast to

the amphipod complex, it has a distinctly patchy distribution in the area (Fig. A.9). The

average biomass of the complex (178.9 ± 39.1 g/m2) is determined primarily by bivalve

mollusks – 37.4% and sand dollars – 31.0%; the contributions of isopods – 15.1% and

polychaetes – 6.7, are considerably smaller.

It is worth noting the aggregations of isopods (primarily Saduria entomon) were

discovered within those complexes. It was highlighted in the course of previous surveys

(Fadeev, 2002-2013; Fadeev, 2003-2012) that the crustaceans' biomass can reach 50% of

the biomass of mollusks within the complex. It was also noted that gray whales usually feed

in this area.

The sand dollar E. parma complex has been described in detail in previous reports

(Fadeev, 2007). Figure A,9 shows where this complex was found within the Piltun feeding

area. We should also note the appearance of conglomerations of another food item within

this complex – the Pacific sand lance (A. hexapterus).

Summarizing the analysis of the distribution of macrobenthos complexes, we note

that there are two complexes that cover most bottom area in the Piltun area, i.e. the shallow-

water, coastal amphipod complex with a high proportion of prey organisms by biomass, and

the deeper-water sand dollar complex with a low proportion of prey organisms by biomass.

The provisional boundary between these complexes lies at depths of about 20 m.



PUBLIC

23

2.2. Benthos Distribution and Abundance in the Chayvo Subarea


Average benthos biomass in the Chayvo subarea in 2015 ranged from 21.6 (st. In12,

depth 11.4 m) to 108.5 g/m2 (st. Ch02, depth 11.5 m) (Fig. A.4) and averaged 43.3 ± 10.1

g/m2 (n=8). For comparison, the level was 66.8 ± 10.0 g/m2 (n=12) in 2015, it was 52.4 ±

5.9 g/m2 (n=12) in 2014, and it was 62.9 ± 6.8 g/m2 (n=12) in 2013. The year-to-year

biomass variations are not statistically significant (t-test, p>0.05).

Seven taxonomic groups of benthos differing in frequency of occurrence (as a

percentage of the total number of stations) were recorded in the Chayvo subarea (Table 5).

The majority of benthos biomass in the waters throughout the Chayvo subarea in 2015, as in

previous years, was made up of groups which were present everywhere (100% occurrence):

amphipods, isopods, polychaetes, cumaceans, and bivalve mollusks. These 5 taxonomic

groups are responsible for more than 85% of the average total benthos biomass for the

subarea as a whole.

Table 5. Frequency of Occurrence of Taxonomic Groups of Benthos in the Chayvo Subarea

Frequency of occurrence (Р, %) of taxonomic groups, n=8

P >50% P = 25-50% P = 10-25% P<10%

Group Р (%) Group Р (%) Group Р (%) Group Р (%)

Amphipoda 100.0 Mysidae 50.0 Decapoda 12.5

Isopoda 100.0

Polychaeta 100.0

Cumacea 100.0

Bivalvia 100.0

In 2016, as in previous years, amphipods account for the major share of the total benthos biomass (55.1%) for the entire subarea.

2.3. Benthos Distribution and Abundance in the Offshore Area


In 2016, 34 stations were sampled (102 bottom grab samples) in the Offshore area at

depths from 22.5 to 61.4 m. Average station depth in 2015 was 45.2±1.8 m (n=34). Station

locations in the Offshore area are shown in Figure A.3.



PUBLIC

24

The average benthos biomass in the Offshore area ranged from 99.7 (st. B1-2, depth

30.1 m) to levels above 4400 g/m2 (st. B5-4, depth 32.5 m) (Fig. A.10) and averaged 878.9 ±

140.1 g/m2 (n=34). For comparison, in 2015 the average biomass was 879.3 ± 92.5 g/m2

(n=48), it was 963.8 ± 125.7 g/m2 (n=48) in 2014, 896.2 ± 112.9 g/m2 (n=48) in 2013, 469.7

± 112 g/m2 (n=48) in 2012, 435 ± 178 g/m2 (n=38) in 2011, and 578.6 ± 123.3 g/m2 (n=48)

in 2010. The significant increase in the benthos biomass starting in 2013 was caused by an

increase in sand dollar biomass. Year-to-year biomass variations for previous years are not

statistically significant (t-test, p>0.05).

The main part of the Offshore area is occupied by sandy soils: the majority (17

samples of 19) of samples collected in the area were made up of well-graded fine sand. A

total of 22 taxonomic groups of benthos were identified in 2016 in the Offshore area. The

frequency of occurrence between these groups (in percentage of total number of samples)

differed substantially (Table 6).

As in previous years, the groups with a biomass contribution occurrence greater than

50% in the Offshore area in 2016 were amphipods, polychaete worms, bivalve mollusks, sea

anemones, cumaceans, gastropods, and decapods. For the Offshore area as a whole, these 7

taxonomic groups accounted for more than 58% of the average total benthos biomass.

Table 6. Frequency of Occurrence of Taxonomic Groups of Benthos in the Offshore Area

Frequency of occurrence (Р, %) of taxonomic groups, n=48

P >50% P = 25-50% P = 10-25% P<10%

Group Р (%) Group Р (%) Group Р (%) Group Р (%)

Amphipoda 100.0 Pisces 41.2 Holothuroidea 20.6 Caprellidae 8.8

Polychaeta 100.0 Nemertini 38.2 Mysidaceae 20.6 Isopoda 5.9

Bivalvia 100.0 Sipunculida 32.4 Hydrozoa 17.6 Anthozoa 2.9

Aсtinia 94.1 Echinoidea 26.5 Echiuridae 14.7 Ophiuroidea 2.9

Cumacea 91.2 Ascidia 11.8

Decapoda 70.6 Bryozoa 11.8

Gastropoda 70.6

2.3.2. Biomass of Amphipods (Amphipoda)

The biomass of amphipods – the most important component in the diet of the whales

in the Offshore area – ranged from 0.14 (st. B12-1, depth 61.4 m) to 802.1 g/m2 (st. B12-2,

depth 60.0 m) and averaged 161.3 ± 39.8 in 2016 (Fig. A11). For comparison, the levels in

2015, 2014, 2013, 2012, and 2011 were 132.3±28.0 g/m2, 178.8±41.3 g/m2,



PUBLIC

25

119.7±20.6 g/m2, 245.8±106.2 g/m2, 176.7±78.5 g/m2, respectively. Year-to-year variations

in the average amphipod biomass are not statistically reliable (p>0.05), which is consistent

with the historic data (Fadeev, 2011, 2009, 2007).

As in previous years of these studies, the biomass amphipods in the Offshore area

increases with distance from the shore toward deeper water (Fig. 5; Fig. A.12). The highest

abundance of amphipods with biomass ≥ 300 g/m2 is found consistently at depths greater

than 50 m (Fig. 5).

Other mass groups (sea anemones, bivalve mollusks, cumaceans, and sand dollars)

that make up most of the remainder of the biomass had a distinctly patchy distribution.

Higher-biomass patches of these groups were located at the edge of the area of abundant

amphipods.

Figure 5. Variations in total amphipods biomass (g/m2) in the Offshore area in 2014-2016 as a function of sampling depth

2.3.3 Composition and Distribution of Benthos Complexes

In 2002-2012 (48 stations) four macrobenthos complexes were identified in the

Offshore area: the sand dollars complex (Complex I), the complex of cumaceans (Complex

II), the complex of Ampelisca amphipod with sea anemones and bivalve mollusks (Complex

III), and the complex of Ampelisca amphipod (Complex IV), occupying the biggest area and

having high importance for gray whale feeding (Fig. A.12).



PUBLIC

26

Different variations in the data for complexes with unchanged primary dominant

species were observed throughout the study period (Fadeev, 2002-2013; Fadeev, 2003-

2012; Ivin and Demchenko, 2014).

Benthos Complex I

A complex dominated by sand dollars Echinarachnius parma (Table 7) occurs mostly

in the northern Offshore area (Fig. A.12). Average depth for this complex is 48.3±4.3 m (7

stations at depths of 32.5–61.4 m). Sand dollars are dominant at all stations, with an average

biomass of 1673.7 ± 477.2 g/m2 (88% of the total biomass). The total biomass of the

complex is 1901.7 ± 468.7 g/m2. The subdominant species is the sea anemone Epiactis

arctica with biomass of 109.8 ± 39.6 g/m2.

A similar complex was described in detail in the Piltun area at depths greater than

20 m (Fadeev, 2007).

Benthos Complex II

A complex dominated by bivalve mollusks (Table 6). The average depth is 33.2±1.4

m (6 stations at depths of 30.1-38.3 m). The average total biomass of the complex is

258.0±52.6 g/m2, and the dominant species account for >77% of biomass (bivalve mollusks

– 56.7%). The complex has a mosaic distribution at depths of 20 to 46 m in the western part

of the area over fine and mixed sands. The subdominant species are the ampelisca amphipod

Ampelisca eschrichti, with a biomass of 28.2±14.8 g/m2; the sea anemone E. arctica, with a

biomass of 25.1±10.7 g/m2, and the cumacean Diastylis bidentata (25.0±11.1 g/m2).

Colony density of cumaceans, D. bidentata, increases significantly along with depth

(Fadeev, 2003). In areas of greatest abundance, their densities become very large, up to

87,000 spec./m2.



PUBLIC

27

Table 7. Quantitative characteristics (biomass, g/m2) of benthos complexes in the Offshore area

Parameter

Taxonomic group Average Total

biomass (Вsumm)

Amphipoda Actinia Bivalvia Echinoidea Cumacea

Complex I. Echinarachnius parma

Average biomass 14.4 109.8 24.3 1673.7 31.8 1901.7

Standard error 6.9 39.6 10.5 477.2 19.8 468.7

Bsumm % 0.8 5.8 1.3 88.0 1.7

Complex II. Bivalviabidentate

Average biomass 28.2 25.1 146.2 0.0 25.0 258.0

Standard error 14.8 10.7 55.3 0.0 11.1 52.6

Bsumm % 10.9 9.7 56.7 0.0 9.7

Complex III. Actinia + Ampelisca eschrichti

Average biomass 100.7 266.6 49.2 1.9. 31.9. 533.3.

Standard error 15.9. 45.1. 7.8. 1.9. 17.7. 54.7.

Bsumm % 18.9. 50.0. 9.2. 0.4. 6.0.

Complex IV. Ampelisca eschrichti

Average biomass 557.2 116.0 216.7 0.0 0.9 1012.6

Standard error 84.6 29.4 82.1 0.0 0.5 141.2

Bsumm % 55.0 11.5 21.4 0.0 0.1

Benthos Complex III

A complex dominated by sea anemones and ampelisca amphipods A. eschrichti.

Average depth is 44.8±1.7 m (13 stations in the range of 33.9-56.2 m). The complex occurs

in patches at the edge of the ampeliscid complex. Average biomass of the complex is

533.3±54.7 g/m2. The dominant species accounted for over 68% of the complex biomass.

The complex includes 19 recorded species of bivalve mollusks.

The complex is dominated by the following species in terms of biomass: sea

anemones E. artica, bivalve mollusks Serripes groenlandicus and Liocyma fluctuosum, and

amphipods A. eschrichti.

Benthos Complex IV

A complex dominated by amphipod A. eschrichti was identified at 7 stations with an

average depth of 56.5±1.3 m (range 50.3-60.0 m). The complex occurred in the eastern part

of the Offshore area. The average total biomass is 1012.6±141.2 g/m2, and the biomass of the

dominant group – amphipods – is more than 550 g/m2 (55.0% of the total biomass). The

complex includes 36 amphipod species, of which 14 species are found only in the Offshore

area. A. eschrichti is distinctly dominant species in terms of frequency of occurrence, colony



PUBLIC

28

density and biomass. Its biomass makes up 95–100% of the total amphipod biomass at

certain individual stations. The maximum ampeliscid biomass had high values over the

entire study period with 90–100% frequency of occurrence. The maximum ampeliscid

biomass had similar high values over the entire study period, with 90–100% frequency of

occurrence (Table 8).

Table 8. Quantitative characteristics (biomass, g/m2) of A. eschrichti in 2004-2016

Year 2004 2005 2006 2007 2008 2009 2010 2012 2013 2014 2015 2016

Max. biomass (g/m2)

1094 1334 1061 1077 1039 1085 1052 1459 1230 1672 905 1072

The ampeliscid colony density and biomass in the Offshore area are comparable to,

and in most cases exceed, the benthic values of other highly productive areas of the North

Pacific (Kuznetsov, 1964; Koblikov, 1983 a, b; 1986; Makarov, 1937) and eastern gray whale

feeding grounds (Stoker, 1981; Nerini and Oliver, 1983; Oliver et al., 1983; Dunham and

Duffus, 2001, 2002; Moore et al., 2007).

2.4. Description of Water Column and Bottom Sediments

2.4.1. Water Temperature

Near-bottom temperatures in the Coastal and the Offshore feeding areas in October

2016 were comparable with those of the corresponding seasons of previous years (Table 9),

except the 2015 observations, when significantly lower near-bottom water temperatures

were recorded.

Table 9. Near-bottom water temperatures (°С) in 2012-2016 in the Coastal and the Offshore feeding areas.

Parameter Coastal area Offshore area

2012 IX

2013 X

2014 X

2015 IX-X

2016 X

2012 IX

2013 X

2014 X

2015 IX-X

2016 X

Average 9.9 8.0 9.0 4.8 8.6 8.2 5.2 8.2 2.7 5.6

Standard error 0.3 0.1 0.1 0.3 0.1 0.2 0.2 0.04 0.9 0.2

Minimum 5.9 6.6 8.1 3.2 6.1 3.9 1.6 7.7 -0.4 1.3

Maximum 12.3 9.6 10.4 8.1 9.4 10.1 7.8 9.4 6.6 7.0

Observations 37 58 58 16 53 30 48 48 9 34

Note. Months are given in Roman numbers: IX – September, X – October.



PUBLIC

29

2.4.2. Structure and Distribution of Bottom Sediments

Particle size distribution of bottom sediments in 2016 is based on laboratory analyses

of 36 soil samples taken at benthos stations (19 stations in the Coastal (Piltun/Chayvo) area

and 17 in the Offshore area). Sediments at most stations throughout the area are

characterized by predominance of sandy (psammite) fractions. Of the 36 stations in all areas,

< 94% are predominately sands, while > 6% have gravel–pebble soils containing some sands

of various grain sizes. The percentage of the fine sand fraction exceeds 75% at most stations.

Coastal area

Field data on soil distribution gathered during 2002–2015 showed that fine sandy

soils predominate at depths above 10–15 m throughout the area. With increasing depth,

these are replaced by medium- and coarse-grained sands and areas with gravel–pebble soils

containing some sands of varying grain size.

The 2016 data reconfirmed this spatial distribution. Fine sands predominated at

> 73% of the entire set of the stations taken in the Coastal area, with medium sands

predominating at > 21% of the stations. Gravel–pebble bottoms, often containing some

sands of various grain sizes, occur in patches at depths greater than 15–20 m. The highest

percentage (more than 10%) of silt-clay fraction in the soil is observed in a local area at

depths below 20 m in the channel area of Piltun Lagoon. The active hydrodynamics of the

area probably promotes the transfer of fine soil fractions to greater depths. Areas with

elevated silt-clay content are found both north and south of the mouth of the lagoon. This is

consistent with hydrology data indicating that during low tides and upwelling, the current

direction along the shoreline in the coastal zone of the Piltun area can change from south to

north.

Offshore Area

The depths in the Offshore area increase gradually from 18 to 68 m. The content of

silt-clay fraction in the soil increases with water depth. Overall, fine sands predominate at

> 95% of the stations in the Offshore area. Gravel soils and coarse-grained sands occur in

patches mainly in the relatively shallow western part of the area.

The 2016 data confirmed such spatial distribution. Most of the samples (15 of 17)

taken in the Offshore area were classified as fine sand.

Classification of Stations According to Similarity of Particle Size Distribution



PUBLIC

30

Data on grain particle size of bottom sediments at stations in the Coastal and the

Offshore areas have been grouped (classified) using cluster analysis procedures (Fadeev,

2007b). Pursuant to the analysis of dendrograms, 3 groups of stations can be identified in all

areas based on the similarity of the grain sizes – A, B, C. Table 10 provides average

characteristics for each sediment group for the Piltun and the Offshore areas based on the

data for the period of 2012-2015.

Group A includes stations with a predominance of 0.1-0.25 mm grain sizes (fine

sands) in the sediment. Based on the Piltun area data for the period of 2012-2015, the share

of that grain size varies from 60 to 96% of the sediment dry weight. The standard entropy

sorting factor averages 0.35 and varies from 0.17 to 0.47 (Ideally sorted sediment has a value

of 0). This group of sediments occurs in the Piltun area at the depths of 9 - 23 m, with an

average depth of 15 m.

Table 10. Characteristics of sediment groups in the Coastal and Offshore areas

Sediment group

Sediment fractions (in % of total) Hs Hs/Hmax Code

Peb Grav Sand

coarse Sand med

Sand fine

Aleu+Pel

Coastal area, 2016 A 0.00 0.43 1.33 12.60 84.38 1.25 0.55 0.25 Sf C 0.00 21.05 13.13 39.69 24.62 1.50 1.53 0.69 Gr+Sfmc

Coastal area, 2015 A 0.00 0.53 0.69 3.59 93.71 1.48 0.30 0.15 Sf B 0.00 1.55 4.32 42.99 50.77 0.36 0.79 0.42 Sfm C 2.66 28.04 19.57 37.89 11.00 0.84 1.42 0.70 Gr+Sfmc

Coastal area, 2014 A 0 9.60 3.36 16.45 68.25 2.34 0.98 0.61 Sf B 0 8.58 26.16 47.63 16.69 0.94 1.26 0.78 Smf

Coastal area, 2013

A 0.00 0.85 3.30 20.50 71.94 3.50 0.83 0.52 Sf B 0.00 14.30 15.73 27.78 39.92 2.27 1.38 0.86 Smf C 0.00 27.04 20.22 35.14 12.74 4.86 1.45 0.90 Gr+Sfmc

Offshore area, 2016

A 0.00 0.43 0.53 3.02 91.77 4.26 0.39 0.18 Sf C 0.00 37.70 19.46 15.14 25.26 2.43 1.69 0.77 Gr+Sfmc

Offshore area, 2015 A 0.08 0.25 0.38 2.27 95.8 1.17 1.85 0.11 Sf B 0.00 0.13 0.29 1.61 91.01 6.95 1.83 0.21 Sf+Al C 0.00 1.97 2.37 34.90 58.70 2.07 1.89 0.45 Sfm D 5.10 18.90 1.10 1.50 67.40 5.90 2.20 0.57 Gr+Sf+Al

Offshore area, 2014 A 0.00 0.24 0.56 4.44 88.20 6.56 0.47 0.29 Sf C 0.00 4.30 6.00 16.30 64.37 9.03 1.10 0.68 Gr+Smf

Offshore area, 2013 A 0.00 0.38 0.74 5.69 85.99 7.20 0.54 0.34 Sf



PUBLIC

31

Sediment group

Sediment fractions (in % of total) Hs Hs/Hmax Code

Peb Grav Sand

coarse Sand med

Sand fine

Aleu+Pel

B 0.00 3.01 7.00 25.40 57.00 7.59 1.16 0.72 Smf C 0.20 39.20 7.50 25.50 19.20 8.40 1.44 0.89 Gr+Smf

Notes: Hs is the entropic index of sediment sorting, and Hs/Hmax is the normalized entropic index

of sorting. Boldface indicates the dominant sediment fraction (dominance is defined as

comprising > 50% of the total weight of the sample).

Group B includes stations where the soil is predominately medium-grained sand

with up to 20% of coarse sand. The entropic index of sediment sorting varies from 0.44 to

0.73, while the average normalized value is equal to 0.61. The average depth of this sediment

group occurrence in the Piltun area is 22 m (depth range 14–26 m).

Group C includes stations without clear dominance of any one fraction. The bottom

is a gravel fraction mixed with sand fractions. The major fractions are 0.5–1.0 mm (coarse

sand) and 1.0–2.0 mm (small gravel). The entropic index of sorting varies from 0.79 to 0.87

(value of absolutely ungraded sediment is equal to 1). The average depth of this group of

stations in the Piltun area is 25 m (depth range 20–37 m).

Group A is well-sorted fine-grained sands, Group B includes medium-sorted sands

of varying grain size (a mixture of fine and medium sands), and Group C includes poorly

sorted sands, characterized by a gravel mixture of varying grain size, pebbles, and shell

detritus. Characteristics of sediment groupings in the Piltun area as described on the basis

of the data for years 2013-2016 are in good agreement with the soil analysis based on the

historic data (Fadeev, 2007).

2.4.3. Organic Matter and Chlorophyll-a in Bottom Sediments

It is generally known that most of the primary biological production on Earth is the

result of photosynthesis of organic matter by green plants (Odum, 1986) that contain the

photosynthetic pigment chlorophyll-a. The main source of organic matter in the ocean is

marine phytoplankton (Skopintsev, 1967; Khaylov, 1971; Behrenfeld et al., 2001;

Romankevich et al., 2009). The leading role in the generation of organic products in bottom

sediments of the littoral zone, especially in the upper layers, is played by a community of

periphytic (benthic) organisms made up mainly of single-celled microalgae, or by

microphytobenthos (Khaylov, 1971; Cherbadzhi and Tarasov, 1980). Since photosynthetic

activity is the basis for biological production, the productivity of the coastal ecosystem can

be judged according to the concentration of the main photosynthetic pigment: chlorophyll-a.



PUBLIC

32

The example of phytoplankton shows that 1 g of chlorophyll assimilates 3.7 g of carbon in 1

hours (Ryter, Yentsch, 1957), which results in a direct relationship between chlorophyll

content and the biological productivity of a reservoir.

Previous research on the ratios of stable isotopes of carbon and nitrogen

demonstrated that the primary sources of organic substances for the most common species

of zoobenthos, which are the basis of the food supply for gray whales in the study area, are

phytoplankton and microphytobenthos (Fadeev, 2008; 2009; 2012; 2013).

Hence the concentrations of organic matter identified in the form of carbon of organic

compounds (Corg.) and chlorophyll in bottom sediments are integral characteristics of the

production water area. At the same time, as previously demonstrated, these characteristics

are interrelated. Moreover, the chlorophyll and Corg. concentrations in bottom sediments are

directly dependent upon the particle size distribution of the sediment and increase from

sand to aleurite and pelite (Romankevich and Vetrov, 2001).

This type of Corg. distribution according to particle size distribution types of sediments

is due to the particle size distribution curve of the bulk of organic matter, the sorption

processes on argillites (oxides), and the hydrodynamic and lithodynamic patterns of particle

movement.

The Corg. concentration ranged from 0.01 to 0.21% and averaged 0.07±0.01% in

bottom sediments of the Coastal area in 2016. The levels are significantly below the 2015

and 2014 data – 0.21±0.11 and 0.28±0.12%, respectively.

The chlorophyll-a concentration ranged from 0.51 to 20.42 mg/100 g of sediment and

averaged 5.04±1.27 mg/100 g in bottom sediments of the Coastal area in 2016. The values

are much higher than the 2015 and 2014 data – 1.76±0.61 and 2.03±0.82 mg/100 g,

respectively.

The Corg. concentration ranged from 0.07 to 0.83% and averaged 0.31±0.06% in

bottom sediments of the Offshore area in 2016. The values are somewhat higher than the

2015 and 2014 data – 0.16±0.07 and 0.24±0.11%, respectively.

The chlorophyll-a concentration ranged from 2.16 to 11.23 mg/100 g of sediment and

averaged 5.95±0.78 mg/100 g in bottom sediments of the Offshore area in 2016. The values

are significantly higher than the 2015 and 2014 data – 1.36±0.47 and 1.42±0.61 mg/100 g,

respectively.



PUBLIC

33

By and large, in spite of the significant deviations from the previous years' levels, the

concentrations of organic matter and chlorophyll-a in the bottom sediments are generally

consistent with the principal types of sediments in the study area.



PUBLIC

34

CONCLUSIONS

1. In 2016, the average benthos biomass in the Piltun feeding area was 621.1 ± 133.7

g/m2 (n=43) and did not differ essentially from the level of previous years (t-test,

p>0.05). As in the previous years for the whole area, sand dollars, Enchinarachnius

parma, prevail in the total benthos biomass, with an average of over 79%, and at the

depths exceeding 20 m sand dollars may account for more than 90%. Quantitative

abundance of the main component of gray whale feeding benthos (amphipods and

isopods) did not differ substantially from previous years. The total crustacean

percentage of macrobenthos biomass was 70.9% at depths less than 11 m; 28.8% in

the depth range of 11–15 m; and only 0.8% at depths greater than 25 m.

2. The average amphipod biomass decreased to 11.1±2.6 g/m2, which is somewhat

lower than in 2015 (14.1±2.5; n=55) and 2014 (16.13±3.29 g/m2; n=56). The year-

to-year biomass variations are not statistically significant (t-test, p>0.05).

Monoporeia affinis is the base of the total amphipod biomass (from 45 to 88%).

Amphipod biomass distribution along the shore of the Piltun feeding area in 2002-

2016 has similar trends: areas of maximum biomass are associated with the shallow

coastal areas.

3. Multi-year changes in amphipod biomass in the Piltun coastal area represent a

statistically significant biomass decrease in 2009 compared to 2002-2008. Amphipod

biomass growth observed in 2010-2012 has not yet reached the maximum biomass

values of 2002-2003 (statistically significant differences still remain). Amphipod

biomass has decreased sharply since 2013. It may possibly be explained by the sharp

decrease in salinity due to heavy water discharge from the Amur River during

catastrophic flooding in 2013, or by their consumption by the steadily growing gray

whale population in the operations area.

4. In 2016, the aggregations of amphipods with an average biomass higher than 40 g/m2

were localized in the southern and central parts of the Piltun area, in the coastal area

near the 10-m isobath in the fine sand zone, and the highest biomass locations in 2016

were associated both with the southern part of the area (the mouth of Piltun Bay) and

the seaward zone in the northern part of the area.

5. Within the Piltun feeding area the lagoon-side complex of amphipod species was

found that was distributed in the south and central parts of the area primarily down

to the depth of less than 15m in the fine sand area, where desalinated, thermally



PUBLIC

35

enriched and biogen enhanced waters constantly flow in from the lagoons.

Monoporeia affinis mixogen species dominates in mass. The portion of this species in

the total amphipod biomass drops down in deeper waters even within the complex

boundaries. Eogammarus schmidti poly-euhaline species are the second significant

ones in terms of biomass in this complex. Bottom sediment types and amphipod mass

species change in the deeper area.

6. Based on analysis of multi-year data of year-to-year and seasonal variations of

amphipods, significant limitations were discovered that associate with the season of

data collection; depth range of data collection; number of stations installed on

minimum and maximum depths; characteristics of seasonal and daily migrations of

amphipods; their aggregated distribution and significant inter-station variability of

their amount and length frequency; location and size of accumulations depending on

hydrological conditions; life cycles of mass species.

7. Analysis of the depths at which samples were collected from 2002 through 2016 does

not consider any methodological errors and does not make it possible to explain the

year-to-year variations in the abundance of amphipods by methodological factors.

8. A continuous increase in average biomass of the sand lance Ammodytes hexapterus to

32.8 ± 10.5 g/m2 was observed in the Piltun area in 2016, with a frequency of

occurrence throughout the study area >63% (n=43), which is above the data of

previous years. For comparison, in 2015 the average biomass of the species in the

Piltun area in 2015 amounted to 27.1 ± 5.2 g/m2 (n=55); in 2014 it was 5.35±1.51

g/m2 (n=56), and in 2013 it was 7.04±1.49 g/m2 (n=58). A significant increase in the

average sand lance biomass in the Piltun area starting in 2015 compared to previous

years (2013-14) holds out a hope of an increase in the abundance of this forage

species.

9. The biocoenosis of bivalve mollusks in the Piltun area included significant

aggregations of isopods (mainly, S entomon), with a biomass of 27.0 ± 24.8 g/m2,

which exceeds 40% of the mollusk biomass. The previous years' observations prove

that these areas are habitual gray whale feeding grounds.

10. The average benthos biomass in the Chayvo feeding area in 2016 was 43.3 ± 10.1

g/m2(n=8), which is lower than the similar figure for 2015, which was 66.8 ± 10 g/m2

(n=12). However, the year-to-year biomass variations are not statistically significant

(t-test, p>0.05).



PUBLIC

36

11. In 2016, the average benthos biomass in the Offshore feeding area was 878.9 ± 140.1

g/m2 (n=34), which is somewhat lower than the 2015 values of 879.3 ± 92.5; (n=48),

and the 2014 levels of 963.8±125.7 g/m2 (n=48). The year-to-year biomass variations

since 2013 are not statistically significant (t-test, p>0.05)

12. In 2016, the amphipod biomass in the Offshore Area was 161.3±39.8 g/m2 (n=34),

compared to 132.3±28.0 g/m2 (n=48) in 2015, and to 178.8±41.3 g/m2 (n=48) in

2014. Year-to-year variations in the average Ampelisca biomass are statistically

unreliable. Spatial distribution of benthos biomass was similar in 2006 – 2016.

Amphipod biomass in the Offshore area increases from the shore toward deeper

water in the eastern part of the area. In 2002 – 2016 benthos biomass was stable in

the Offshore feeding area; there are no significant year-to-year variations.

13. Maximum amphipod biomass in the Ampelisca eschrichti biocoenosis in 2016 was

about 1072 g/m2, and matches the levels of the previous study years, which are

comparable to, and in most cases exceed, the benthos levels in other highly

productive regions of the North Pacific.

14. As in previous study years, the amphipod biomass in the Offshore area increases

away from the shore toward deeper waters. The highest abundance of amphipods

with a biomass over 300 g/m2 was found consistently at depths of over 50 m.

15. The chlorophyll-a concentration ranged from 0.01 to 0.21% and averaged

0.07±0.01% in the bottom sediments of the Coastal area in 2016. The acquired values

are significantly lower than the 2015 and 2014 figures – 0.21±0.11 and 0.28±0.12%,

respectively. The concentration levels ranged from 2.16 to 11.23 mg/100 g of

sediment and averaged 5.95±0.78 mg/100 g in the bottom sediments of the Offshore

area. The acquired values significantly exceed the 2015 and 2014 figures – 1.36±0.47

and 1.42±0.61 mg/100 g, respectively.

16. The Corg. concentration ranged from 0.01 to 0.21% and averaged 0.07±0.01% in the

bottom sediments of the Coastal area in 2016. The acquired values are significantly

lower than the 2015 and 2014 data – 0.21±0.11 and 0.28±0.12%, respectively. The

parameter ranged from 0.07 to 0.83% and averaged 0.31±0.06% in the bottom

sediments of the Offshore area. The acquired values are slightly higher than those in

2015 and 2014 – 0.16±0.07 and 0.24±0.11%, respectively.

17. By and large, in spite of the notable deviations from the levels of previous years, the

chlorophyll-a and Сорг. concentrations in bottom sediments are consistent with the



PUBLIC

37

primary types of sediments in the study area. The prevalence of sandy soils with

minimal fine silt content does not promote the accumulation of organic matter or

chlorophyll-a.



PUBLIC

38

REFERENCES

Ivin V.V., Demchenko N.L. 2014. “State of Benthos in the Feeding Grounds of Gray Whales

(Eschrichtius Robustus) off the Northeast Coast of Sakhalin in 2014.” Unpublished

report under a contract of the Marine Biology Institute, Russian Academy of Sciences

Far East Branch, Vladivostok, Russia, for Exxon Neftegas Limited, Yuzhno-Sakhalinsk,

Russia, and Sakhalin Energy Investment Company Limited, Yuzhno-Sakhalinsk, Russia.

Koblikov V.N. 1983a. Quantitative Characteristics of the Benthic Population of Waters of the

Sea of Okhotsk off Sakhalin // Quantitative and Qualitative Distribution of Benthos:

Food Supply for Bottom-Feeding Fish. Moscow: VNIRO. Pp. 4-21.

Koblikov V.N. 1983b. Macrobenthos Composition and Quantitative Distribution on the

Sakhalin Shelf of the Sea of Okhotsk // Izv. TINRO. V. 106. Pp. 90-97.

Koblikov V.N. 1986. Benthic Communities of the Continental Shelf and the Upper Part of the

Sakhalin Coastal Slope of the Sea of Okhotsk. TINRO. Guide, on deposit at VsNIITEIRKh.

54 pp.

Krasavtsev V.B., Puzankov K.L., Shevchenko G.V. Upwelling Development on the Northeast

Shelf of Sakhalin Island // DVNIGMI Special Issue No. 3. Vladivostok: Dalnauka, 2000.

Pp. 106-120.

Kuznetsov A.P., 1964. Distribution of Benthos Fauna in the Western Bering Sea [Kuznetsov,

A.P. 1964. Distribution of benthic fauna in the western Bering Sea by trophic zones and

general issues of trophic zonation // Trans. Inst. Okeanol. AN SSSP. V. 69, P. 98-177].

Makarov V.V. 1937. Quantitative Survey Data on Benthic Fauna of the Northern Bering and

Chukchi Seas // Issled. dalnevostochnykh morey SSSR. Issue 25. Pp. 260-289.

Odum Yu. 1986. Ecology. Moscow: Mir. Two volumes.

Pishchalnik V.M., Arkhipkin V.S. Seasonal Variations of Water Circulation on the Sakhalin

Shelf of the Sea of Okhotsk // DVNIGMI Special Issue No. 2. Vladivostok: Dalnauka,

1999. Pp. 84-95.

Romankevich Ye.A., Vetrov A.A. 2001. The Carbon Cycle in the Arctic Seas of Russia. Moscow:

Nauka, 302 pp. Romankevich Ye.A., Vetrov A.A., Peresypkin V.I. Organic Matter of the

Ocean // Geologiya i geofizika. 2009. V. 50, No. 4. Pp. 401-411.

Rutenko A.N., Khrapchenkov F.F., Sosnin V.A. Coastal Upwelling on the Sakhalin Shelf //

Meteorologiya i gidrologiya. 2009. No. 2. Pp. 44-53.



PUBLIC

39

Rutenko A.N., Sosnin V.A. Hydrodynamic Processes on the Sakhalin Island Shelf in the Coastal

Piltun Gray Whale Feeding Area and Their Relationship to Atmospheric Circulation //

Meteorologiya i gidrologiya. 2014. No. 5. Pp. 74-93.

Skopintsev B.A. The Organic Carbon Balance in Ocean Waters // Dokl. AN SSSR. 1967. V. 174,

No. 6. Pp. 1417-1425.

Fadeev V.I. 2002. “Benthos Diving Studies in Gray Whale Feeding Areas in 2001.”

Unpublished final report under a contract of the Marine Biology Institute, Russian

Academy of Sciences Far East Branch, Vladivostok, Russia, for Exxon Neftegas Limited,

Yuzhno-Sakhalinsk, Russia, and Sakhalin Energy Investment Company Limited,

Yuzhno-Sakhalinsk, Russia. 113 pp.

Fadeev, V.I. 2004. “Benthos and Prey Studies in Feeding Grounds of the Western Gray Whale

Population.” Report on materials from field studies on the research vessel Nevelskoy in

2003 // Report under a contract of the Marine Biology Institute, Russian Academy of

Sciences Far East Branch, Vladivostok, Russia, for Exxon Neftegas Limited, Yuzhno-

Sakhalinsk, Russia, and Sakhalin Energy Investment Company Limited, Yuzhno-

Sakhalinsk, Russia.


Population. 2004.” Unpublished report under a contract of the Marine Biology Institute,

Russian Academy of Sciences Far East Branch, Vladivostok, Russia, for Exxon Neftegas

Limited, Yuzhno-Sakhalinsk, Russia, and Sakhalin Energy Investment Company

Limited, Yuzhno-Sakhalinsk, Russia.






Fadeev, V.I. 2007а. “Benthos and Prey Studies in Feeding Grounds of the Western Gray Whale







PUBLIC

40

Fadeev, V.I. 2013а. “State of Benthos in Feeding Grounds of the Sakhalin Feeding Aggregation

of Gray Whales in 2012. Methods and Analysis.” Unpublished report under a contract

of the Marine Biology Institute, Russian Academy of Sciences Far East Branch,

Vladivostok, Russia, for Exxon Neftegas Limited, Yuzhno-Sakhalinsk, Russia, and

Sakhalin Energy Investment Company Limited, Yuzhno-Sakhalinsk, Russia.

Fadeev, V.I. 2013b. “State of Benthos in Feeding Grounds of the Sakhalin Feeding Aggregation

of Gray Whales in 2012. Methods and Analysis.” Unpublished report under a contract

of the Marine Biology Institute, Russian Academy of Sciences Far East Branch,

Vladivostok, Russia, for Exxon Neftegas Limited, Yuzhno-Sakhalinsk, Russia, and


Khaylov K.M. Ecological Metabolism in the Sea. Kiev: Nauk. Dumka. 1971. 252 pp.

Cherbadzhi I.I., Tarasov V.G. Photosynthesis and Respiration of Benthic Communities on

Soft Soils of Vostok Bay (Sea of Japan) // Biologiya morya. 1980. No. 2. Pp. 21-30.

Behrenfeld M.J., Randerson J.T., McClain C.R. Biospheric primary production during an ENSO

transition // Science. 2001. Vol. 291. Р. 2594-2597.

Dunham, J.S. and D.A. Duffus. 2001. Foraging patterns of gray whales in central Clayoquot

Sound, British Columbia. Marine Ecology Progress Series 223:299-310.

Dunham, J.S. and D.A. Duffus. 2002. Diet of gray whales (Eschrichtius robustus) in Clayoquot

Sound, British Columbia, Canada. Marine Mammal Science 18: 419-437.

Fadeev, V.I. 2003. Benthos and Prey Studies in Feeding Grounds of the Western Gray Whale

Population. Report on materials from field studies on the research vessel Nevelskoy in

2002. Report by the Institute of Marine Biology, Far East Branch of Russian Academy

of Sciences, Vladivostok, Russia, for Exxon Neftegas Limited and Sakhalin Energy

Investment Company, Yuzhno-Sakhalinsk, Russia - 118 pp.

Fadeev, V.I. 2004. Benthos and Prey in Feeding Grounds of the Western Gray Whale

Population. Report on materials from field studies on the research vessel Nevelskoy in

2003 // Report by the Institute of Marine Biology, Far East Branch of Russian Academy


Investment Company, Yuzhno-Sakhalinsk, Russia. 191 pp.

Fadeev, V. I. 2005. Benthos and food supply in feeding areas of the Western gray whale

population. Report based on results of field work aboard the research vessel Akademic

Oparin. Report by the Institute of Marine Biology, Far East Branch of Russian Academy



PUBLIC

41


Investment Company, Yuzhno-Sakhalinsk, Russia. 157 pp.

Fadeev, V. I. 2006. Benthos and food supply in feeding areas of the Okhotsk–Korean gray

whale population in 2005. Report by the Institute of Marine Biology, Far East Branch of

Russian Academy of Sciences, Vladivostok, Russia, for Exxon Neftegas Limited and

Sakhalin Energy Investment Company, Yuzhno-Sakhalinsk, Russia. 133 pp.

Fadeev, V.I. 2007a. Benthos and food supply in feeding areas of the Western gray whale

population. Unpublished contract report by the Institute of Marine Biology, Far Eastern

Branch of the Russian Academy of Science, Vladivostok, Russia, for Exxon Neftegas

Limited, Yuzhno-Sakhalinsk, Russia and Sakhalin Energy Investment Company Limited,

Yuzhno-Sakhalinsk, Russia. 119 pp.

Fadeev V.I. 2007b. Investigations of benthos and food resources in summer feeding areas of

the Western Gray Whale Population Eschrichtius robustus in 2001-2003 // Response

of Marine Biota to Environmental and Climatic Changes. Vladivostok: Dalnauka, P. 213–

231.

Fadeev, V.I. 2008. Benthos and prey studies in feeding grounds of the Western Gray Whale

Population, 2007. Report by Institute of Marine Biology of Far East Branch, Russian

Academy of Sciences for Exxon Neftegas Limited, Yuzhno-Sakhalinsk, Russia and


Fadeev, V.I. 2009. Benthos studies in feeding grounds of the Western gray whale population.

Report by the Marine biology institute (The Far East Branch), Russian Academy of

Sciences. Vladivostok, Russia for Exxon Neftegas Limited, Yuzhno-Sakhalinsk, Russia

and Sakhalin Energy Investment Company Limited, Yuzhno-Sakhalinsk, Russia.

Fadeev, V.I. 2010. Benthos studies in feeding grounds of the Western gray whale population

in 2009. Chapter 3 In: Western Gray Whale Research and Monitoring Program in 2009,

Sakhalin Island, Russia. Volume II Results and Discussion. Report by the Marine Biology

Institute (The Far East Branch), Russian Academy of Sciences. Vladivostok, Russia for

Exxon Neftegas Limited, Yuzhno-Sakhalinsk, Russia and Sakhalin Energy Investment

Company Limited, Yuzhno-Sakhalinsk, Russia.






PUBLIC

42



Company Limited, Yuzhno Sakhalinsk, Russia.






Company, Yuzhno-Sakhalinsk, Russia.

Moore, S. E., K. M. Wynne, J. C. Kinney and J. M. Grebmeier. 2007. Gray whale occurrence and

forage southeast of Kodiak Island, Alaska. Marine Mammal Science 23:419–428.

Nerini M.K., J.S. Oliver. 1983. Gray whales and the structure of the Bering Sea benthos //

Oecologia (Berlin). V. 59. P. 224 – 225.

Oliver, J.S., P.N. Slattery, M.A. Silberstein and E.F. O'Connor. 1983. A comparison of gray

whale feeding in the Bering Sea and Baja California // Fisheries Bull V. 81. P.:501-512.

Ryter J.H., Yentsch C.S. The estimation of phytoplankton production in the ocean from

chlorophyll and light data. Limnol. Oceanogr., 1957, 2, 281-286.

Stoker, S. W. 1981. Benthic invertebrate microfauna of the eastern Bering/Chuckchi

continental shelf. // In: In the eastern Bering Sea shelf: oceanography and resources,

vol. 1, (eds.) D. W. Hood and J. A. Calder. Off. Marine Pollution Assessment, NOAA.

Distributed by University of Washington Press, Seattle.



PUBLIC

43

APPENDIX



PUBLIC

44

Figure A.1. Locations of sampling stations in the Piltun area.



PUBLIC

45

Table A.1. List of stations in the Piltun area used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel

Item Station code Coordinates

Depth (m) Latitude Longitude

1 1-1N 52.876923 143.345303 12.10

2 1-1M 52.808690 143.354767 7.94

3 1-1S 52.724133 143.352180 13.02

4 1-2M 52.969980 143.320190 11.08

5 1-2S 52.928429 143.331275 10.45

6 1-3N 53.170008 143.284113 12.15

7 1-3M 53.116658 143.288600 10.15

8 1-3S 53.083813 143.300925 12.20

9 1-4N 53.321463 143.228146 13.03

10 1-4M 53.256363 143.253858 12.30

11 1-4S 53.215096 143.273542 13.35

12 1-5M 53.448571 143.158679 13.83

13 2-1N 52.856687 143.360143 15.34

14 2-1M 52.828930 143.366017 13.00

15 2-1S 52.764400 143.355033 11.84

16 2-2N 53.003046 143.336550 14.75

17 2-2M 52.976900 143.351643 20.28

18 2-3M 53.127558 143.305933 15.60

19 2-4N 53.307179 143.253892 20.68

20 2-4S 53.237421 143.287754 21.73

21 2-5M 53.424704 143.194850 23.80

22 2-5S 53.368371 143.229983 23.48

23 3-1N 52.842896 143.395742 21.75

24 3-1M 52.797017 143.387423 16.72

25 3-1S 52.737467 143.385903 20.52

26 3-2N 53.023740 143.373270 24.50

27 3-2M 52.955580 143.371217 24.84

28 3-2S 52.790325 143.376163 19.35

29 3-3M 53.130946 143.351833 23.35

30 3-3S 53.094446 143.350421 26.68

31 3-4N 53.316750 143.287154 28.28

32 3-4M 53.273042 143.310542 25.43

33 3-4S 53.224775 143.307267 24.18

34 3-5N 53.489958 143.178146 29.73

35 3-5M 53.413042 143.221867 26.88



PUBLIC

46

End of Table A.1



36 4-1N 52.845960 143.426790 23.54

37 4-1M 52.825193 143.428390 21.84

38 4-1S 52.746923 143.420567 18.42

39 4-2M 52.955447 143.405233 27.32

40 4-3N 53.213721 143.356533 28.30

41 4-3S 53.071525 143.378533 26.53

42 4-4M 53.292033 143.329083 29.80

43 4-4S 53.238304 143.331508 26.55

44 4-5N 53.477629 143.211788 33.48

45 4-5M 53.433533 143.245350 33.70



PUBLIC

47

Figure A.2. Locations of sampling stations in the Chayvo subarea.

Table A.2. List of stations in the Chayvo subarea used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel



1 In21 52.652437 143.341743 10.16

2 In12 52.618108 143.343400 11.40

3 In32 52.590092 143.340450 10.83

4 In22 52.542853 143.337867 12.24

5 Ch01 52.507308 143.325146 11.48

6 Ch02 52.500388 143.322192 11.60

7 Ch03 52.488217 143.319260 11.02

8 Ch04 52.469238 143.313900 11.20



PUBLIC

48

Figure A.3. Locations of sampling stations in the Offshore area.



PUBLIC

49

Table A.3. List of stations in the Offshore area used from October 3 through October 26, 2016, for surveys from the Pavel Gordienko Research Vessel



1 B1-2 52.058327 143.386317 30.14

2 B1-3 52.226100 143.381329 22.53

3 B2-2 52.062260 143.432373 31.48

4 B3-1 51.958529 143.450417 32.30

5 B3-3 52.197047 143.478483 30.36

6 B4-1 51.918967 143.508913 36.80

7 B4-3 52.178403 143.511280 33.86

8 B5-1 51.982250 143.550608 43.08

9 B5-2 52.100697 143.583813 42.70

10 B5-4 52.377592 143.566458 32.45

11 B6-1 51.947313 143.591797 47.22

12 B6-2 52.098071 143.603063 44.25

13 B6-3 52.225827 143.593707 36.90

14 B6-4 52.377017 143.591850 34.85

15 B7-1 51.926123 143.628697 50.86

16 B7-3 52.229592 143.636175 39.85

17 B7-4 52.402110 143.641623 38.22

18 B8-1 51.894908 143.671338 56.48

19 B8-2 52.048640 143.691860 48.80

20 B8-3 52.232963 143.672879 42.10

21 B9-1 51.921853 143.733937 57.84

22 B9-2 52.106921 143.724975 50.33

23 B9-3 52.185540 143.723413 48.18

24 B9-4 52.330483 143.750367 47.78

25 B10-1 51.903640 143.752703 59.36

26 B10-3 52.235388 143.740279 48.18

27 B10-4 52.341263 143.755457 47.86

28 B11-1 51.992575 143.813383 57.75

29 B11-2 52.140623 143.810730 53.58

30 B11-3 52.190233 143.833963 56.23

31 B11-4 52.321907 143.800530 53.12

32 B12-1 51.973887 143.878603 61.40

33 B12-2 52.046660 143.866320 59.96

34 B12-4 52,372025 143,872775 60,90



PUBLIC

50

Figure A.4. Average benthos biomass (g/m2) distribution in the Piltun and Chayvo areas in 2016.



PUBLIC

51

Figure A.5. Average isopod biomass (g/m2) distribution in the Piltun and Chayvo areas in 2014-2016.



PUBLIC

52

Figure A.6. Amphipod biomass (g/m2) distribution in the Piltun and Chayvo areas in 2014-2016.



PUBLIC

53

A B

Figure A.7. Distribution of temperature °С (A) and salinity ‰ (B) in the Piltun and Chayvo areas during the study period.



PUBLIC

54

Figure A.8. Distribution of biomass (g/m2) of sand lance Ammodytes hexapterus in the Piltun and Chayvo areas in 2014-2016.



PUBLIC

55

Figure A.9. Distribution of benthos complexes in the Piltun area



PUBLIC

56

Figure A.10. Distribution of average benthos biomass (g/m2)complexes in the Offshore area in 2016.

Figure A.11. Amphipod biomass (g/m2) distribution in the Offshore area in 2016.



PUBLIC

57

Figure A.12. Distribution of average benthos biomass (g/m2) complexes in the Offshore area based on long-term study data. Numbers of complexes are provided in the text.



PUBLIC

the state of benthos in the feeding grounds of gray whales filethe state of benthos in the feeding...

Documents