"Economic Development and the Environment"
on the Sakhalin Offshore Oil and Gas Fields II

Copyright (C) 1999 by Slavic Research Center, Hokkaido University.
All rights reserved

Oil and Gas Development on the Sakhalin Island Shelf: An Assessment of Changes in the Okhotsk Sea Ecosystem

Alexander Leonov



Fig. 1 Correlation between the oil product concentration (LC50) for marine organisms with their size characteristics [1]:
1 - adult species; 2 - early stages of ontogenesis; 3 - values of effective concentrations (EC50) for unicellular algae; n - numbers of data; r - correlation coefficient; (dash line indicates data do not taken into account in calculations).


Fig. 2 Correlation between the survival time of growing roe of marine invertabrates with the roe size at the incubation into 0.5% solution of diezel fuel and sea water [1]:
1 - Molluska; 2 - Echenodermata; 3 - Annelida; 4 - Urochordata; 5 - Arthropoda (Balanus cariosus).

Fig. 3 Range of toxic (rectangles) and treshold (fat lines) concentrations of dissolved oil fractions for basic marine organism groups (unshaded part - areas of toxic concentrations for early stages of ontogenesis; numbers in right side - amount of studied species). Toxic concentration indicate ranges of the content in environment at which measured indexes have reliably decreased more than on 50% from the control in experiments continued 2-4 days. Treshold concentrations indicate the minimum content in environment at which measured indexes have decreased on 50% in experiments comparable in the time with ontogenesis of studied organism [1].

Fig. 4 Approximate levels of biological action and ranges of specific oil hydrocarbon content in sediments [1]:
1 - pelagic zone of seas and oceans; 2 - coastal zones; 3- bays, estuaries, inlets, ports and other, 4 - areas of strong pollution at oil spills, disposals and etc.