Space Study of a Red Tide-Related Environmental Disaster near Kamchatka Peninsula in September–October 2020

The results of space monitoring of an extreme ecological situation near Kamchatka Peninsula, which was responsible for a mass death of hydrobionts in autumn 2020, are presented. The analysis of long-term series of satellite data (>15 000 scenes) on sea surface temperature (from 1981 to 2020) and concentration of chlorophyll a (from 2000 to 2020) showed strong positive temperature anomalies (deviations from a climate norm 3–6°C) in the studied region in July–September 2020, which resulted in anomalous increase in the concentration of chlorophyll a (5–8 times higher than the background values) in the end of September–the beginning of October 2020. As a result, a significantly changed biogenic regime led to harmful bloom of algae (red tide), which caused death of hydrobionts both in Avacha Bay and coastal regions of the entire Kamchatka Peninsula.

Copper-Containing Agates of the Avacha Bay (Eastern Kamchatka, Russia)

The copper-containing agates of the Avacha Bay (Eastern Kamchatka, Russia) have been investigated in this study. Optical microscopy, scanning electron microscopy, electron microprobe analysis, X-ray powder diffraction, Raman spectroscopy, and fluid inclusions were used to investigate the samples. It was found that copper mineralization in agates is represented by native copper, copper sulphides (chalcocite, djurleite, digenite, anilite, yarrowite, rarely chalcopyrite) and cuprite. In addition to copper minerals, sphalerite and native silver were also found in the agates. Native copper is localized in a siliceous matrix in the form of inclusions usually less than 100 microns in size—rarely up to 1 mm—forming dendrites and crystals of a cubic system. Copper sulphides are found in the interstices of chalcedony often cementing the marginal parts of spherule aggregates of silica. In addition, they fill the micro veins, which occupy a cross-cutting position with respect to the concentric bands of chalcedony. The idiomorphic appearance of native copper crystals and clear boundaries with the silica matrix suggest their simultaneous crystallization. Copper sulphides, cuprite, and barite micro veins indicate a later deposition. Raman spectroscopy and X-ray powder diffraction results demonstrated that the Avacha Bay agates contained cristobalite in addition to quartz and moganite. The fluid inclusions study shows that the crystalline quartz in the center of the nodule in agates was formed with the participation of solutions containing a very low salt concentration (<0.3 wt.% NaCl equivalent) at the temperature range 110–50 °C and below. The main salt components were CaCl2 and NaCl, with a probable admixture of MgCl2. The copper mineralization in the agates of the Avacha Bay established in the volcanic strata can serve as a direct sign of their metallogenic specialization.

State of stocks of pacific salmons in the basin of Avacha Bay (southeastern Kamchatka) in 1985–2019

State of pacific salmon stocks is considered for the basins of the Avacha and Paratunka Rivers in 1985–2019. Significant decline of the stocks is noted that is associated with anthropogenic impact growth. Total number of producers for five salmon species in the Paratunka is almost twice higher than in the Avacha, with the largest portion of pink salmon, then chum salmon, lower portion of coho salmon, and the smallest portions of sockeye and chinook salmons, which need special protection. The main biological parameters of salmons are analyzed for both rivers, as body length, weight, fecundity, sex ratio and age structure, by species. Relationships between the parameters are revealed; their long-term trends are determined. Abundance of wildly and artificially hatched chum salmon is compared.

Characteristics of Short-Period Internal Waves in the Avacha Bay Based on the In Situ and Satellite Observations in August-September, 2018

Purpose. The paper is aimed at evaluating the characteristics of short-period internal waves in different regions of the Avacha Bay in the Рacific Ocean concerning their hydrological and morphometric conditions. Methods and Results. The characteristics of internal waves are assessed through synthesizing the results of the in situ studies in the Avacha Bay in August-September, 2018, the high-resolution remote sensing data and the results of tidal modeling. The data of the in situ and satellite observations of internal waves were also directly compared. The results show that in the shallow part of the Avacha Bay, the waves, whose heights are from 10 to 15 m were observed. They constitute 10 % of the total number of cases. In the deep-water part of the bay, the internal waves are also often observed, but their maximum height does not exceed 10 m. The satellite images show 72 manifestations of short-period internal waves. Some of them spread to the coast with a tidal frequency from the generation source located around the 500 m isobath where the bottom abruptly slows down. Conclusions. The results of the investigation revealed a pronounced relationship between the wave trains recorded in the shallow-water area and the semidiurnal tidal dynamics. Analysis of the hydrological situation and the satellite images permitted to assume that the internal waves could be generated as a result of not only a barotropic tide collapse, but also due to the inertial oscillations of the frontal zone formed by the Kamchatka current meanders in the presence of a shallow sharpened pycnocline. Having been analyzed, the synchronous satellite and in situ observations made it possible to find out that the internal waves of the 5–8 m height were distinctly manifested on the sea surface in case the pycnocline depth was 10–20 m.