Ecological investigations at North East Sakhalin Island shelf, including monitoring around Molikpaq platform

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1 Ecological investigations at North East Sakhalin Island shelf, including monitoring around Molikpaq platform T.A. Belan, T.V. Konovalova, A.V. Moschenko, T.S. Lishavskaya, A.V. Tkalin, E.V. Karasev, A.S. Chernova and N.K. Khristoforova

2 Introduction Since 90s, FERHRI scientists began ecological investigations along the NE Sakhalin Island shelf in relation to possible oil and a gas development in the region. In , observations were carried out at Lunskoe and Piltun-Asokhskoye oil fields, along future pipeline routes and in some bays (Chayvo, Nabil,, Aniva, etc.). The main goal of these observations was to get background characteristics of the marine environment in the study areas. Observations around Molikpaq platform were implemented in in order to estimate the changes in the marine environment quality around the platform. Studies included measurements of numerous parameters of seawater, bottom sediments, pelagic and bottom communities.

3 55.0 Polygons Transect 53.0 Piltun Bay 1 1. Piltun-Astokh field 2. Pipeline 3. Lunskoye field 4. Aniva Bay 5. Kholmsk Location of the study areas in Lunsky Bay Tatarsky Strait Sakhalin Island 5 4 Sea of Okhotsk In this presentation, results of monitoring around the Molikpaq platform are presented

4 Methods Most informative monitoring parameters are characteristics of bottom sediments and benthic fauna. Therefore, sediment grain size, concentrations of trace metals and petroleum hydrocarbons in bottom sediments and characteristics of benthos were used as monitoring parameters. In this study, mainly methods of multivariate statistics (cluster analysis and factor analysis) were used as these techniques allow to distinguish natural variability from anthropogenic changes.

5 Sediment grain size Using area-averaged averaged grain size distribution data, increase of fine sand fraction was observed in 1998, probably due to sediment relocation during the platform installation. Further investigations in have shown that sediment grain size characteristics became similar to background values.

6 Grain size: sediment types 1,5 1,0 0,5 5000S 250E 125S 500S 125W 500E 125N 3000E 5000N REF01 REF W 0,0 1000S 125E 3000N 500W -0,5-1,0 250N 3000S 1000N -1,5 250S 500N -2,0-2,5 250W -3,0-1,5-1,0-0,5 0,0 0,5 1,0 1,5 2,0 2,5 3,0 Фактор 1 Factor analysis allowed to distinguish four main types of sediment: fine, medium and coarse sands, and gravel.

7 Content of PHCs Maximum petroleum hydrocarbon (PHC) content in bottom sediments (22.7 ppm) was observed in June 1998 before platform installation. From October 1998 to October 2001, maximum PHC concentrations decreased from 11.1 to 6.0 ppm (average concentrations decreased from 1.4 to 0.9 ppm). Total concentrations of polyaromatic hydrocarbons (PAH) were two orders of magnitude below values which could cause negative biological effects (Long et al., 1995). Therefore, the concentrations of PHC and PAH observed did not reveal any negative anthropogenic effects around the platform.

8 Content of PHCs 2,0 1,8 1,6 1,4 1,2 1,0 0,8 0,6 0,4 0,2 0,0 Июнь 1998 г. Октябрь 1998 г. Октябрь 1999 г. Октябрь-Ноябрь 2000 г. Сентябрь-Октябрь 2001 г.

9 Trace metals in bottom sediments Concentrations of most trace metals (except barium) in were orders of magnitude below the values which might cause negative biological effects (Long et al., 1995) Contents of Ba in 1999 were several times higher that background values, most probably due to drilling discharges from the platform.

10 Distribution of Zn in bottom sediments in 1999 and S 3000S 1000S 500S 250S 125S 125N 250N 500N 1000N 3000N 5000N W 1000W 500W 250W 125W 125E 250E 500E 1000E 3000Е

11 Distribution of Ba in bottom sediments in 1999 and S 3000S 1000S 500S 250S 125S 125N 250N 500N 1000N 3000N 5000N W 1000W 500W 250W 125W 125E 250E 500E 1000E 3000Е

12 Benthos (1) Benthos analysis have shown that faunistic groups are quite stable. This fact confirms the absence of negative anthropogenic influence associated with the Molikpaq platform operations.

13 Benthos: the dynamics of biomass of the basic faunistic groups (the data from 4 surveys, October 1998 October 2001) 6% 11% 21% 9% 9% 3% 27% 14% Ac tinia ria Amphipoda Bivalvia Cumacea Echinoidea Gastropoda Polychaeta Прочие 25% 1% 12% 3% 20% 13% 3% 23% Ac tinia ria Amphipoda Bivalvia Cumacea Echinoidea Gas tropoda Polychaeta Прочие 1% 8% 5% 12% 7% 11% Ac tiniaria Amphipoda Bivalvia Cumacea Echinoidea 2% 8% 6% 18% 4% 8% Ac tiniaria Amphipoda Bivalvia Cumacea Echinoidea 34% 22% Gastropoda Polychaeta Прочие 35% 19% Gastropoda Polychaeta Прочие

14 Benthos (2) Cluster analysis of benthic samples for have revealed four stable bottom communities. These clusters are associated with specific types of bottom sediments: 1. Monodominant community of fine sands, where sea urchin Echinarschnius parma dominated. 2. Monodominant community of fine and medium sands, where cumacean Diastylis bidentata prevailed. These communities were characterized by low species diversity and the highest biomass and\or abundance. 3. Polydominant community of the coarse sands, where a few species were prevailed (sea anemone Halcampoides purpurea,, sea urchin E. parma, polychaete Nephtys caeca,, bivalve Mysella kurillensis) ). 4. Polydominant community of gravel sediments. Dominate species were presented by sessile animals (sea anemone Epiactis arctica, polychaetes N. caeca and Ampharete lindstromi, hydroides, tunicates, sponges). Polydominant agglomerations characterized by the highest species diversity and low biomass (abundance).

15 Benthos: cluster analysis ( , 5 surveys)

16 Conclusions 1. Pollutant contents around the Molikpaq platform are typical for the NW Pacific marginal seas, any negative changes in the marine environment were not detected so far. 2. The relocation of bottom sediments and drilling from the platform were not associated with the elevated contents of petroleum hydrocarbons and trace metals (except Ba) ) in bottom sediments. The pollutant contents in were 1-22 orders below of threshold concentrations (Long et al., 1995). 3. Benthos species composition and faunistic groups around the platform have not changed, the only variations observed were associated with the grain size changes. Changes in grain size (and associated changes in benthic communities) are caused mostly by strong near-bottom currents in the study area.

Akvaplan-niva rapport

Grunnlagsundersøkelse på Snøhvit og Område C i Barentshavet, 2003 Akvaplan-niva rapport APN-411.2785-1 Introduction Statoil and Norsk Hydro commissioned Akvaplan-niva AS to perform baseline surveys at