The Kamchatka River Estuary. The results of the complex surveys of the river ecosystem. Part I
PRESENT-DAY MORPHOLOGICAL STRUCTURE AND HYDROLOGICAL CONDITIONS OF THE KAMCHATKA RIVER ESTUARY
HYDROLOGY, RIVER MOUTH AREA, ESTUARY, WATER MASSES, WATER MIXTURE, GEOMORPHOLOGY,SEASHORE, THE KAMCHATKA RIVER
Basing on the results of 2009–2010 field studies, detailed characteristics of morphological structure and hydrological conditions of the Kamchatka river Estuary (both the whole estuary and its water bodies — the Nerpich’e, Kultuchnoe Lakes, side channel Ozernaya and mouth lagoons) are discussed. In this connection a lot of facts describing the estuary with its active processeses and the estuary’s environmental conditions are given.
ENDOGENOUS GEOLOGICAL PROCESSES AND THE HOLOCENE HISTORY OF THE KAMCHATKA RIVER MOUTH AREA
T.K. Pinegina, A.I. Kozhurin*, V.V. Ponomareva
GEODYNAMICS, ACTIVE TECTONICS, GEOLOGICAL AND GEOMORPHOLOGIC STRUCTURE OF THE TERRITORY, HOLOCENE HISTORY
In geodynamic terms, mouth zone of the Kamchatka River may belong to the Kamchatka peninsula area. The peninsula is a tectonic block separated from the Kumroch Range by an active fault which makes the main boundary between the colliding Aleutian and Kamchatkan island arcs. All the study zone is located within the convergent junction of the 3 biggest plates — Eurasian, North American and Pacific. The plates’ interaction causes active faulting, earthquakes and tsunamis, which in their turn determine the course and peculiarities of active surface processes. The main traits of geological and geomorphologic structure and Holocene history of the mouth zone of the Kamchatka River as well as basic active crustal processes obviously affecting it are discussed.
DIATOMS FROM HOLOCENE SEDIMENTS OF THE NERPICH'E LAKE (KAMCHATKA)
M.V. Cherepanova*, E.V. Lepskaya, P. Anderson**, A.V. Lozhkin***
DIATOMS , PALEOECOLOGY, THE NERPICH'E LAKE, KAMCHATKA
Diatoms from the bottom sediments of the shoreline zone of the Nerpich’e Lake have been examined. Relative stability of species diversity and composition of the dominant group forming by euryhalophilic shallow water inhabitants (Melosira dubia and M. lineata) reflected no sharp or catastrophic environmental changes during Middle and Late Holocene. Changed composition of freshwater and marine species in the bottom sediments’core is the evidence of periodical influence of climatic and sea-level changes, happened during the Holocene period, on the study area. Sea water falling into the lake increased the water salinity of its bottom area and brought sea species.
DATA ON THE CENTROPHYCEAE DIATOMS FLORA OF THE NERPICH’E LAKE (ESTUARINE WATER BODY OF THE KAMCHATKA RIVER)
S.I. Genkal*, Е.V. Lepskaya
CENTROPHYCEAE DIATOMS, ELECTRON MACROSCOPY STUDIES, THE NERPICH’E LAKE, THE KAMCHATKA RIVER ESTUARY
Scanning electron microscopic studies of diatoms in the Nerpich’e lake (estuarine water body of the Kamchatka River) revealed broadened taxonomic structure of Centrophyceae, there is an increase in the species number (from 5 to 29) and in the genera number (from 3 to 9) giving 6 new species found in the lake flora of Kamchatka (Cyclotella atomus, Melosira arctica, Stephanodiscus delicatus and S. makarovae, Thalassiosira baltica, T. lacustris) and one new species discovered in today’s diatom flora of Russia (T. cf. allenii). Most of them are freshwater species able to live in conditions of changing water salinity. Sea forms are constantly present in the benthopelagic boundary layer of stable water salinity similar to that of coastal waters or can be brought by high tide currents and seldom by tsunami.
PELAGIC ZOOPLANKTON OF ESTUARINE WATER BODIES OF THE KAMCHATKA RIVER IN 2009−2011
ZOOPLANKTON, ESTUARY, THE KAMCHATKA RIVER
Species composition, seasonal variations in the structure and quantities of pelagic zooplankton of estuarine water bodies of the Kamchatka River in 2009–2011 have been studied. Neritic crustaceous species never observed here in the middle of the 20th century were found in the zooplankton despite no changes in the salinity of the water basins. Rotatoria constituted 60% of the total number of zooplankton. Only in winter and spring periods the abundance of crustaceous exceeded the abundance of Rotatoria in the sections with medium and strong replacement of water. The present research shows that in the years of cold summer a 1–1.5 month retardation of zooplankton’s development happens. Average abundance of zooplankton in the Nerpich’e-Kultuchnoe lakes network in October of 2009, March, end of June and August of 2010 was 51, 4, 17 and 268 thousand units/m3, and the biomass was 107, 9, 47 and 321 mg/m3. At the end-August of 2011 — year of low temperatures there were 19 thousand units/m3 and 38 mg/m3. Since the years 1950−1960s of the XXth century the food supply of planktivorous fishes in the lakes network has not undergone changes.
DYNAMICS OF DISTRIBUTION AND ABUNDANCE OF MACROZOOBENTHOS IN THE LAKE SYSTEM NERPICH’E–KULTUCHNOE (THE KAMCHATKA RIVER ESTUARY)
MACROZOOBENTHOS, SPECIES COMPOSITION, STRUCTURE, ABUNDANCE, BIOMASS
Three areas in the lake system differing by composition and abundance of macrozoobenthos are distinguished. Benthos is shown to be more varied and abundant in the areas of intensive and moderate water replacement. Accumulation of hydrogen sulfide in the soil prevents benthic fauna growth in the area of poor water replacement (northern sector of the Nerpich’e Lake and the hollow of the Kultuchnoe Lake). Temporary improvement of ecological conditions as well as settling of chironomids in late summer is possible only for the northern sector of the Nerpich’e Lake where active wind shuffling reaches its bottom zone.
FEEDING OF RAINBOW SMELT, STARRY FLOUNDER, SAFFRON COD, PACIFIC HERRING AND SALMONIDS WITHIN THE KAMCHATKA RIVER ESTUARY
FEEDING, FOOD OBJECTS, INDEXES OF STOMACH FULLNESS
Feeding characteristics for rainbow smelt (10–28 cm), starry flounder (11–29 cm), saffron cod (26–40 cm), Pacific herring (8–34 cm), char (18–62 cm), malma (17–36 cm), sockey salmon (11–16 cm) and coho salmon (11–27 cm) within the Kamchatka River estuary are given. Food composition peculiarities for some fish species in the vast area of the Nerpich’e and Kaltuchnoe Lakes as well as the features of their stomach fullness, arising from irregular distribution of food objects, are revealed.
FISH FAUNA, SPATIAL DISTRIBUTION AND INTERSPECIFIC FOOD RELATIONS OF ABUNDANT FISH STOCKS IN THE EPIPELAGIAL OF THE KAMCHATKA GULF DURING GROWTH PERIOD OF JUVENILE PACIFIC SALMONS
М.V. Koval, А.V. Morozova
FISH FAUNA, EPIPELAGIAL, TRAWL SURVEY, ABUNDANT SPECIES, SPATIAL DISTRIBUTION, INTERSPECIFIC FOOD RELATIONS, PASIFIC SALMONS
Results of the registration trawl surveys made by Kamchatka Research Institute of Fisheries and Oceanography in the Kamchatka Gulf in August of 2007 and 2010 have been reported. Species compound of the catches, peculiarities of distribution and migration, feeding and interspecific food relations of young Pacific salmons and other abundant fish species stocks are described. The obtained data show that the fish fauna of the epipelagial of the Kamchatka Gulf during the early period of sea feeding migration of juvenile salmons may include 25 fish species, the most abundant of which are herring and Alaska pollock. These species are also the most probable rivals of juvenile salmon fish in food. Maximum catches of almost all fish species in August are observed in the northern Kamchatka Gulf — not far from the Kamchatka River mouth area. After downstream migration from the Kamchatka River (up to the mid-August) there are favorable conditions for growth of young salmon in nearshore environment as it has richer food resources in comparison with the openwater zone. The following factors (or their sum total) serve as the main reasons why young salmon fish remove from the shallow water to the deeper Kamchatka Gulf at the end of August: the average size of young fish reaches 10 cm and more; sharp interspecific rivalry in food caused by increasing abundance of herring on the shelf during its migration to the Nerpich’e Lake, nearshore water temperature falls while in open water it rises up to the maximum level creating favorable environment for young fish.