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The embryogenesis of the sea urchin sand dollar Scaphechinus mirabilis was used as bioindicators of seawater quality from the impact areas of the Sea of Japan/East Sea (Peter the Great Bay) and the Sea of Okhotsk (northwestern shelf of Sakhalin Island and western shelf of Kamchatka Peninsula). Fertilization membrane formation, first cleavage, blastula formation, gastrulation, and 2-armed and 4-armed pluteus formation have been analyzed and a number of abnormalities were calculated. Number of embryogenesis anomalies in sand dollar larvae exposed to sea water from different stations in Peter the Great Bay corresponds to pollution level at each area. The Sea of Okhotsk is the main fishing area for Russia. Anthropogenic impact on the marine ecosystem is caused by fishing and transport vessels mainly. But two shelf areas are considered as "hot spots" due to oil and gas drilling. Offshore oil exploitation on the northeastern Sakhalin Island has been started and at present time oil is being drill on oil-extracting platforms continuously. Significant reserves of hydrocarbons are prospected on western Kamchatka shelf, and exploitation drilling in this area was intensified in 2014. A higher number of abnormalities at gastrula and pluteus stages (19-36%) were detected for the stations around oil platforms near Sakhalin Island. On the western Kamchatka shelf number of abnormalities was 7-21%. Such anomalies as exogastrula, incomplete development of pairs of arms were not observed at all; only the delay of development was registered. Eggs, embryos, and larvae of sea urchins are the suitable bioindicators of early disturbances caused by marine pollution in impact ecosystems.

Microplastic pollution appears to be one of the major environmental problems in the world today, and researchers have been paying special attention to the study of the impact of microplastics on biota. In this article, we studied the short-term effects of polystyrene micro-spheres on genome integrity using the gametes of the Scaphechinus mirabilis sand dollar with the comet assay method. This highly sensitive method allowed us to identify the level of genome damage in both gametes before and after short-term exposure to PS microparticles. It was shown that primary polystyrene microspheres at concentrations of 104, 105, and 106 particles/L had a genotoxic effect during short-term exposure to the sperm of the sand dollar S. mirabilis, which was expressed as a significant increase in sperm DNA damage. The highest percentage of DNA damage (more than 20%) was detected in spermatozoa exposed for 1 h in water containing 105 microspheres of plastic per 1 L. Additionally, at all concentrations of microplastic studied in the experiment, the genetic damage index (GDI) values in spermatozoa exceeded the control level. However, regardless of the level of DNA damage, spermatozoa retained the ability to fertilise eggs with up to 97% efficiency. We must acknowledge that the genotoxic property of microplastic against sperm to some extent predicts the development of long-term adverse effects of environmental significance.