Amur Bay Research Articles

A STUDY OF PROPERTIES OF GENERALIZED MODEL FOR INTERANNUAL DYNAMICS OF EPIPHYTIC DIATOM COMMUNITIES

Modeling the dynamics of the relative number of diatoms in epiphytic diatom communities of the macrophyte Ulva lactuca Linnaeus from three different coastal areas of Peter the Great Bay, Sea of Japan (Amur Bay, Ussuri Bay, and the Stark Strait), based on a tool of recurrent equations, makes it possible to identify the communities’ own natural dynamics in the water areas studied [Parensky, Levchenko, 2018]. It has been found that the reproductive capacity of the epiphytic diatom communities decreases in the following sequence: Amur Bay — Ussuri Bay — Stark Strait. As reported in literature, the nitrogen and phosphorus enrichment of the above-mentioned water areas decreases in the same sequence [Zvalinsky et al., 2013]. A relationship existing between the relative number of epiphytic diatoms and the level of trophicity of their habitat is assumed. Possible variants of relationships of the model coefficients with the trophicity level, including the necessary point (X = 0, Z = 0), are considered. Trophicity has proven to regulate all parameters of the multistep recurrent models describing the relative number of epiphytic diatoms. A generalized recurrent model for regulation of the relative number of epiphytic diatoms has been built; in this model, a regulating (trophic) factor is added to two limiting factors (photosynthetically active radiation and oxygen). A study of the model has shown that the trophicity level influences the interannual dynamics of the relative diatoms’ number and the duration of communities’ existence.

SOME DATA ON BIOLOGY AND FISHERY OF ICEFISH SALANGICHTHYS MICRODON IN PETER THE GREAT BAY (JAPAN SEA)

Within Peter the Great Bay, common icefish Salangichthys microdon forms commercially valuable aggregations in two areas of the Amur Bay and in one area of the Ussuri Bay. It spawns in the internal estuaries of the rivers entered to the bays and in the external estuarine zones in the tops of the bays, mostly on small pebble grounds from late April to late May and feeds in the bays waters. Data on its size and weight composition were obtained in 2017–2018 both from the Amur Bay (for spawning period) and from the Ussuri Bay (for feeding period). During the spawning (on May 6 and May 18), the body length was 59–90 mm, on average 74.9 mm, and the weight was about 750 mg; sex ratio males : females was 1.0 : 0.8. During the feeding, the average body length was 66.8 mm.

MODERN CONTAMINATION OF BOTTOM SEDIMENTS AND ECOLOGICAL STATE OF MACROZOOBENTHOS IN THE COASTAL ZONE AT VLADIVOSTOK (PETER THE GREAT BAY, JAPAN SEA)

Contamination of bottom sediments in Peter the Great Bay is spatially variable, but for majority of stations it exceeds the natural geochemical background and «safe» level with at least one pollutant, mainly with hydrocarbons, pesticides, cadmium and mercury. The main sources of contaminants are the waste discharge of Vladivostok and other cities (oil products, pesticides, phenols, heavy metals: Cd, Cu, Hg, Pb, Zn) and rivers fall into the northern parts of Amur and Ussuri Bays (Co, Mn, Ni, Fe). The Golden Horn Bay and the Bosphorus East Strait are the most polluted areas, where concentrations of both heavy metals and hydrocarbons exceed the natural background and «safe» level considerably. The Amur Bay has moderate contamination, and the Ussuri Bay is contaminated slightly. Recently the chemical contamination and eutrophication are the main factors that determine the ecological status of bottom populations, though the former one is valid locally, in the most contaminated areas only.

Accumulation of heavy metals in sediments of Amur Bay (Sea of Japan) under the infl uence of biochemical factors

The average content of the elements Fe, Mn, Zn, Pb, Cu, Cr, V, Co, Cd, Ni, As, and Mo in the subcolloidal fraction of bottom sediments in the northern and central parts of the Amur Bay (in Russia) was determined. An increase of 5–17% in the content of the metals Pb, Co, Ni, Zn, Cr, V, and As in bottom sediments affected directly by the Razdolnaya River was determined and was found to be associated with sorption on Fe and Mn oxyhydroxides. An increase of 21–55% in the content of the metals Cu and Mo and of the metalloid As compared to their average content in the bottom sediments of the bay was found to be associated with the accumulation by humic substances.

Accumulation of Heavy Metals by Amur Bay Sediments (the Sea of Japan) under the Effect of Biochemical Factors

The average concentrations of elements Fe, Mn, Zn, Pb, Cu, Cr, V, Co, Cd, Ni, As, and Mo in the subcolloidal fraction of bottom sediments were determined in the northern and central parts of the Amur Bay. The concentrations of metals Pb, Co, Ni, Zn, Cr, V, and As in bottom sediments subject to direct influence of the Razdol’naya River were shown to increase by 5–17% because of their sorption on Fe and Mn oxy hydroxides. The concentrations of some elements (As, Cu, and Mo) in the bottom sediments of the bay were found to be 21–55% above their average concentrations because of their accumulation by humic substances.

Dynamics of the Organic Matter Content of Bottom Sediments along the Razdolnaya River–Amur Bay Boundary (Sea of Japan)

The contents of Corg, humiс acids (HA), and fulvic acids (FA) in soil and riverine and marine bottom sediments have been investigated along a transect between the Razdolnaya River and Amur Bay. The revealed higher Corg content of soil compared to that of riverine and marine sediments is associated with peatlands. The increased HA content of sediments compared to the FA content, corresponding to the initial period of water mixing, is explained by flocculation. The identified riverine sediments with increased FA, Fe, and Mn contents indicate active processes of flocculation and the formation of Fe and Mn oxyhydroxides. Soil shows significantly larger amounts of humified organic matter than marine sediments. Marine sediments contain mostly biochemically unrecycled organic matter.

A Yesso Scallop Population Exposed to Climate-Induced and Anthropogenic Habitat Changes in Amur Bay, Sea of Japan

In the study area, located in the coastal waters of Amur Bay off Vladivostok, which is exposed to industrial and domestic sewage effluents, the population of the Yesso scallop Mizuhopecten (=Patinopecten) yessoensis and the community of the endo- and epibiosis of its shell underwent major changes during the period 1981–2016, in which three main stages can be identified. During the first stage, which lasted until the early 1990s, the growth rate and lifespan of the scallop decreased, but the mortality rate and the degree of shell bioerosion grew. This stage coincided with the period of increased anthropogenic pollution in Amur Bay. In the mid-1990s, which was a transitional period, the decline in the scallop growth rate ceased. At that time environmental pollution decreased due to reduced sewage discharge as industrial production fell. During the second stage, which lasted until the mid-2000s, the scallop growth rate increased, but the degree of bioerosion and abundance of epibionts on the scallop shell reduced. That was a period when the bay underwent gradual natural self-purification. During the third stage, which continues until present, the scallop growth rate has declined again due to increased eutrophication, which leads to lower oxygen saturation of water. This is most evident during periodic increases in water temperature associated with the quasi-biennial and 7- to 8-year temperature fluctuation cycles. Poaching is a negative anthropogenic that has caused a substantial reduction in scallop population density.

Reconstructing the Frequency of Catastrophic Floods on the Western Coast of the Sea of Japan Based on Sedimentary Proxy

The history of coastal catastrophic floods was reconstructed for the first time using the geochemical proxy in shelf sediments. The reconstruction is based on the identification of sediment layers accumulated on the shelf during the intensive discharge of the river runoff suspended matter from the land which does not contain bromine. The set of isotopic (AMS 14C, 210Pb, 137Cs), tephrastratigraphic, and paleomagnetic methods was used for the detailed chronology of sediments. The scanning of chemical composition of sediments with the step of 0.5–0.8 mm is performed using the synchrotron radiation X-ray fluorescence in the VEPP-3 storage of the Institute of Nuclear Physics of Siberian Branch of Russian Academy of Sciences. The history of catastrophic floods for the past 1800 years is reconstructed based on the typical variations in bromine concentration in one of the cores from the Amur Bay (the Sea of Japan). New methodological approaches to the flood signal extraction are proposed. The revealed inverse correlation between the frequency of floods caused by typhoons over the coast of the Sea of Japan and southern China agrees with the existing assumption on the change in their trajectories in different periods of global climate change.

Diatoms in the Amur Bay sediments (Sea of Japan) and the impact of typhoons on their accumulation over the last 2000 years

The study of diatoms in the sediments of the Amur Bay (Sea of Japan), formed over the last 2000 years, showed that the sharp short-term drops in the concentration of diatoms coincide with the minima of bromine content, which can be explained by the influence of typhoons or other catastrophic events leading to floods and used later in paleoreconstructions.

ВЛИЯНИЕ ТАЙФУНОВ НА СОДЕРЖАНИЕ ДИАТОМЕЙ В ОСАДКАХ АМУРСКОГО ЗАЛИВА (ЯПОНСКОЕ МОРЕ) ЗА ПОСЛЕДНИЕ 150 ЛЕТ

This paper presents the results of study of diatoms in each centimeter of sediments in cores A12-4 and A12-5 from Amur Bay (Sea of Japan) that have formed over the last 150 years. Diatom algae show significant changes in the quantitative content and ecological structure of the assemblages, which reveal the conditions of sediments accumulation. The study showed that in lithologically homogeneous sediments, with relatively high sedimentation rates and the absence of bioturbation, sharp short-term diatoms concentration declines coincide with the minimum bromine content associated with extreme floods caused by typhoons, which can be used in paleoreconstructions. The results confirm the data on the increase in the intensity and frequency of typhoons over the past 60 years in the study area due to global warming.

Current state and structure of native aggregations of pacifc oyster in the northern Amur Bay (Peter the Great Bay, Japan Sea)

Spatial distribution and reproductive ability of the pacifc oysterCrassostrea gigasaggregations in the northern Amur Bay (Peter the Great Bay, Japan Sea) are investigated using the data of direct and remote accounts. Totally 772 oyster banks and reefs are detected with the summary area of 284.6 hectares that is signifcantly larger than earlier assessments. The 35 giant beds (> 1 ha) occupy 53.2 % of the summary area, but 79.8 % of mollusks gather in medium and large aggregations which occupy 45.5 % of the summary area. Majority of the aggregations (> 95 %) are located on shallows with the depth less than 5 m. The oyster matur-ing is completed when it reaches the size of 50 mm. The ratio of males to females is 1.0 : 1.5, on average, that indicates indirectly favorable habitat conditions forC. gigas. Males prevail among the small-sized individuals, but females prevail among the large-sized ones that corresponds to reproductive strategy of pacifc oyster and type of its reproduction. The males to females ratio changes from year to year. Portion of young mollusks is rather high (13.9–56.2 %), portion of the main reproductive groups changes from 40.6 to 88.9 % that indicates active processes of natural reproduction and the oyster reefs forming. Mollusks with high reproductive rate prevail among the main reproductive group with the size 70–130 mm (58.2 %). The largest number of such individuals is observed in the largest aggregations of oysters at Rechnoy Island (85.0 %) and at Skrebtsov Island (60.7 %). Spatial variations of the shells shape and ratio of size-physiological groups in the aggregations reflect patterns of the habitat conditions. Generally, the state of native oyster aggregations in the northern Amur Bay is stable with a tendency to their population increasing.

Fluctuations of the Amur Bay in winter

Fluctuations of the Amur Bay in winter

A Study of the Properties of the Multi-Step Recurrent Models for the Interannual Dynamics of Epiphytic Diatom Communities

Communities of epiphytic diatoms develop seasonally. On macroalgae, they reach the highest density in the middle of summer and decline to a minimum value in winter. This discrete pattern makes it possible to use the tool of difference (recurrent) equations for testing the concept of density regulation on the interannual dynamics of the number of epiphytic diatoms. The properties of the obtained multi-step recurrent models for the interannual dynamics of the number of diatoms in the epiphyton of the macroalga Ulva lactuca Linnaeus collected from three areas of coastal waters in Peter the Great Bay, Sea of Japan (Amur Bay, Ussuri Bay, and Stark Strait), are considered. The proposed multi-step recurrent models do not contradict the primary data of observations. Each of the obtained descriptions for different water areas is characterized by its specific pattern of dynamics. The reproductive capacity of epiphytic diatom community is the lowest in the Stark Strait; the highest reproductive capacity is observed in Amur Bay. According to the models, the epiphytic diatom communities in different parts of Peter the Great Bay exhibit generally complex, pseudochaotic, dynamics of their number.

Accumulation of Subcolloidal Fraction Elements of Bottom Sediments in Amur Bay (Sea of Japan)

The mean contents of elements (Fe, Mn, Zn, Pb, Cu, Cr, V, Co, Cd, Ni, As, Sc, Ga, Zr, Hf, Nb, Ta, W, Th, Mo) in the subcolloidal fraction of bottom sediments in the northern part of Amur Bay have been determined. A 5–17% increase is observed in the heavy metal content (Pb, Co, Ni, Zn, Cr, V, As) compared to the mean values for sediments directly subjected to the influence of the Razdolnaya River, which is related to flocculation and sorption on Fe and Mn oxyhydroxides. A linear dependence of heavy metal accumulation on the Fe and Mn content is established. An increase in the Cu and Mo content is revealed (by 49 and 44%, respectively), related to vital accumulation by plankton, as well as in increase in V, Cr, Co, Ni, Zn, Cd, and As (by 2–20%) in sediments subjected to anthropogenic impact.

Qualitative and quantitative composition of phytoplankton in the Golden Horn Bay, Japan Sea

Qualitative and quantitative composition of phytoplankton in the Golden Horn Bay (Japan Sea) was investigated in the period from October 2009 to October 2010. The water samples of 1 L volume were taken with Molchanov bottle at the 36th Berth where ship-repairing yards were located and naval and commercial ships were moored. The samples were fixed in Utermӧhl iodine solution and phytoplankton cells were concentrated by precipitation or by reverse fil­tration, then the concentrated samples were processed under microscope. In total, 135 species and intraspecific taxa of microalgae were detected, which belonged to 7 divisions. Average density of phytoplankton cells varied from 1.9 . 103 to 610.3 . 103 cells/L, its average biomass varied from 0.02 to 11.70 g/m3. Four peaks of the phytoplankton cells density were registered: in summer, spring, winter and fall (in descending order), with the highest density in June, but only one peak of the phytoplankton biomass was observed in February. The highest density (up to 1 . 106 cells/L) was formed by euglenophytes that was similar to the neighboring Amur Bay and obviously indicated organic pollution of the Golden Horn Bay waters. Comparing with results of previous observations in the 1990s and 2000s, the species diversity of dominant diatoms and euglenophytes has increased recently. These species are known as indicators of eutrophic waters and/or organic pollution.

A STUDY OF PROPERTIES OF THE RECURRENT MULTI-STEP MODELS FOR INTERANNUAL DYNAMICS OF DIATOM ALGAE COMMUNITIES IN EPIPHYTON

Epiphytic diatoms develop seasonally. On macrophytes they reach the highest density in the middle of summer and have the minimum density in winter. This pattern gives an opportunity to apply a tool of difference (recurrent) equations for testing the concept of density regulation in interannual dynamics of their number. Detailed scheme of the model is developed; the model is applied for the diatoms dynamics in macroalgae epiphyton of Ulva lactuca Linnaeus in three areas of Peter the Great Bay, Japan Sea (Amur Bay, Ussuri Bay, and Stark Strait). The model parameters are evaluated by means of SYSTAT 5 and STATISTICA 8 software. The model results do not contradict the data of observations. Its determination (R2 ) exceeds 0.62 in all cases. Selected coefficients of the model have rather small relative errors (< 11 %) which never change the sign of the coefficients. Generally, the modelled dynamics of relative number of epiphytic diatom communities is complicated, pseudochaotic. It differs between the areas. Reproductive capacity of the epiphytic diatom community is the lowest in the Stark Strait and the highest in the Amur Bay. In both these areas, alternation patterns are modelled as periods of chaotic dynamics and the periods with a limit cyclicity. Resistance of the epiphytic diatom communities to variations of the main limiting factors of the environments decreases in the order: Amur Bay — Stark Strait — Ussuri Bay.

CHANGES IN COMPOSITION OF FISH AND DECAPODS CATCHES ALONG SALINITY GRADIENT IN THE RAZDOLNAYA RIVER AND TOP OF THE AMUR BAY IN THE WARM PERIOD OF YEAR

Quantitative samples of fish, crabs and shrimps from the Razdolnaya estuary are analyzed. The area surveyed in May-September of 1990–2014 includes the internal estuary of this largest river of southern Primorye and its external estuary — the top of the Amur Bay with the depth < 13 m. In total, 478 samples were collected: 244 in the external estuary by trawl and 234 in the internal estuary by fry seine. Distribution density and biomass are calculated using the «areal» method with certain coefficients of catchability (1.0 for fry seine). The upper freshwater layer (salinity 0–5 ‰) was observed in the lower stream of the river till sandy bar, the brackish-water cline was traced at the river bottom from the mouth to the distance 10–15 km upstream. The seawater with salinity > 30 ‰ did not penetrate over sand bar to the river. Species diversity of fish and decapods was presented by 108 taxa (fishes — 88, decapods — 20) belonged to 43 families, among them 84 species were caught in the Amur Bay and 41 species in the Razdolnaya, but no more than 67 species were caught in the Amur Bay only and 24 species — in the Razdolnaya only, other 17 species were found in both external and internal estuaries (Acanthogobius flavimanus, Acanthogobius lactipes, Crangon septemspinosa, Crangon spp., Eriocheir japonica, Hypomesus nipponensis, Giporhamphus sajori, Konosirus punctatus, Liopsetta pinnifasciata, Oncorhynchus masou masou, Palaemon sp., Pholis nebulosa, Planiliza haematocheila, Pugettia quadridens, Salangichthys microdon, Syngnathus schlegeli and Tribolodon spp.). Total biomass was higher (9.1 g/m2 ) in the external estuary than in the internal estuary (6.7 g/m2 ) with the mean value 9.0 g/m2 . It was almost uniform over the internal estuary with only slight increasing on the distance about 5 km from the mouth. Simpson index of dominance increases from external to internal estuary but decreases in the river in the order: 0.127 at Peschany Peninsula — 0.168 in the northwestern Amur Bay — from 0.193 to 0.252 in the internal estuary — 0.164 in the river. Six clusters with similar species composition are defined, they change in direction from the sea to the river in the following order of the dominant species: L. pinnifasciata in the sea — prawns gen. Palaemon at the bar (upper part of the external estuary) — P. haematocheila at the river mouth (lower part of the internal estuary) — P. haematocheila and E. japonica in the main part of the internal estuary — Acanthorhodeus chankaensis and Gobio macrocephalus (with the highest biomass up to 22 g/m2 ) in the minor adjoining river stream — G. macrocephalus in the upper part of the internal estuary.

SEASONAL CHANGES OF VERTICAL PROFILES OF CHLOROPHYLL A IN THE AMUR BAY (JAPAN SEA)

Seasonal changes of chlorophyll a profiles are traced over the Amur Bay (Peter the Great Bay, Japan Sea) in May-October, 2017 by means of oceanographic sonde-profiler equipped with fluorometer. Two principally different types of the vertical profiles are revealed, which were formed by different mechanisms of productivity: i) Chl a concentration had the maximum at the sea surface and decreased with the depth in the internal part of the bay occupied by the estuarine waters, and ii) Chl a concentration had the maximum below the seasonal pycnocline in the external part of the bay connected with the open sea. The highest Chl a concentration was observed in July-August for the estuarine type because of summer monsoon flood on the rivers, but in September for the marine type because of the coastal upwelling induced by monsoon winds change. Comparing these results with estimations of Chl a concentration made with the satellite data, insufficient correspondence is concluded for the external part of the bay, outside the estuarine zone, because the satellite data don’t reflect well the chlorophyll a in the subsurface layer and its seasonal variations. Thus, underestimation of real productivity and feeding ability of marine areas is available with the satellite data on chlorophyll a.

Основные особенности сезонной и многолетней динамики сообщества зоопланктона Амурского залива (залив Петра Великого, Японское море)

Основные особенности сезонной и многолетней динамики сообщества зоопланктона Амурского залива (залив Петра Великого, Японское море)

Investigation of hypoxia in the Eastern Bosporus (the Peter the Great Gulf, the Sea of Japan)

The seasonal distribution of hypoxia in the bottom waters of the Eastern Bosporus (the Peter the Great Gulf, the Sea of Japan) is analyzed based on long-term observational data (2006-2013). It is revealed that in summer the monthly mean concentration of oxygen in the bottom waters considerably decreased as compared to average long-term data. The minimum values of oxygen concentration were registered during four months, from July to October. It is demonstrated that the small values of oxygen concentration are mainly caused by the inflow of hypoxic water from the Amur Bay.