scholarly journals Daily dynamics of vertical distribution and amount of sturgeons in riverbed depression in summer-autumn period

2019 ◽  
Vol 2019 (4) ◽  
pp. 55-69
Author(s):  
Andrey Stepanovich Aldokhin ◽  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Water Column ◽  
Vertical Migration ◽  
Water Area ◽  
Fish Distribution ◽  
Vertical Position ◽  
Near Surface ◽  
Level Regime ◽  
Total Fish ◽  
Irtysh River ◽  
Riverbed Depression

The article presents the results of studying the fish distribution in the water column of the riverbed depression using remote echometric sounding with a software-hardware acoustic system with a vertical view. The study was conducted in the lower reaches of the Irtysh River. In the appointed period (July-October) under a decrease in the level regime and water temperature the increasing density of fish in the water area of the riverbed depression is explained by fish gathering in the period preceding wintering. The share of sturgeons varied from 5.46 to 10.28% of the total fish density, the indicators of which were in the range 1.70-5.05 thousand sp/ha in the daytime, 2.78-6.77 thousand sp/ha in the night. There has been stated the daily vertical migration of sturgeons, which is more uniform throughout the water column in the night, including the near-surface and near-bottom water horizons. In the dark near-surface water horizons are most intensively explored by large fish (25-30, 30-35, > 35 cm). The trigger of the daily vertical migration of sturgeons is supposed to be the light brightness, despite the poor eyesight of the fish under study, i.e. changing vertical position of sturgeons occurs due to endogenous circadian rhythms, as in many hydrobionts. The recorded features of sturgeon distribution because of preference of the direction and intensity of various factors can contribute to the optimization of bioenergy losses in hard turbulent conditions of riverbed depressions.

scholarly journals DISTRIBUTION OF FISH IN THE PREDATOR-PREY SYSTEM IN THE RIVERBED DEPRESSION OF THE LOWER IRTYSH

2017 ◽  
pp. 76-84
Author(s):  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Water Area ◽  
Bottom Surface ◽  
Predator Prey ◽  
Prey System ◽  
Irtysh River ◽  
Riverbed Depression ◽  
Distribution Of Fish ◽  
The Irtysh River

The article presents are features of the horizontal and vertical distribution of fish in the water area of the Kondinskaya riverbed depression in the lower reaches of the Irtysh River (Tyumen region, Russia). There have been considered horizons of the water column from the surface to the bottom: surface-pelagic horizon (< 10 m), 1st pelagic horizon (10-20 m), 2nd pelagic horizon (20-30 m), and bottom-pelagic horizon (> 30 m). Hydroacoustic survey was conducted using a software and hardware complex "AsCor" on board a small ship that moved in tacks (zigzags). The recorded information, including the GPS track, processed with special application software "AsCor". Taxonomic belonging to the families was determined remotely - by the type of the reflected sound. According to the data of echometric sensing, main part of fish population on the studied water area was presented by carp species (Cyprinidae) - 66.81%, perch species (Percidae) - 23.77%, cisco species (Coregonidae) - 5.60%, unrecognized species (sturgeon (Acipenseridae)), eelpout species (Lotidae), pike species (Esocidae)) - 3.82% of the registered plurality of fish. All fish groups of the registered mass in terms of abundance have been distributed predominantly in the surface and 1-st pelagic horizons of the water column of the riverbed depression. The difference in the distribution of registered taxonomic fish groups in the vertical aspect from the surface to the bottom is different: in planktivorous fishes more than 190 times, in predatory fishes from 10 to 27 times. A more even distribution of predatory species reduces their aggressive interaction - interspecific and intraspecific competition. There has been revealed a tendency to decrease the percentage of planktivorous species (Cyprinidae) in each succeeding horizon in direction from the surface to the bottom; for Percidae and Coregonidae species and a group of unrecognized fishes it was established, vice versa, in the direction from the bottom to the surface. Due to the wedge-shaped decrease of the living space in the riverbed, the general tendency of a decrease in the number of fish has been registered in the direction of deeper horizons. There has been noted the statistical reliability of differences in the vertical distribution for all registered fish groups. The features of the fish distribution in the predator-prey system on the Irtysh river section with heterogeneous conditions of the aquatic environment (intensive ascending currents and funnels, significant depth changes) characterize it as a "window of antipredation".

scholarly journals FISH POPULATION OF GORNOSLINKINSKAYA RIVERBED DEPRESSION OF THE LOWER IRTYSH IN WINTER PERIOD

2018 ◽  
pp. 39-47
Author(s):  
Gleb Igorevich Volosnikov ◽  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Water Column ◽  
Fish Population ◽  
Water Area ◽  
Fish Distribution ◽  
Winter Period ◽  
Composition Control ◽  
Ecological Features ◽  
Hydroacoustic Survey ◽  
Riverbed Depression ◽  
Distribution Of Fish

Fish distribution was studied using sonar computerized complex in the deep part of the water column of Gornoslinkinskaya riverbed depression in winter. In the horizontal aspect there was estimated the number of fish registrations, in the vertical aspect the fish density was analyzed in three conditional horizons of the water column: surface, pelagic, bottom. Additionally, the bathymetric characteristics of the riverbed depression in the fish registration areas were evaluated. In the study period the depths were lower than 40 m. On the trajectory of the planned research route there were drilled holes in ice with a motor-drill (screw D=200 mm). Hydroacoustic survey was performed for each drilled hole. To control the species composition control fishing was carried out by gillnets. The hydroacoustic survey files were further processed in the laboratory using AsCor and Taxonomy applications for carrying out dimensional-taxonomic identification of fish. It has been established that fish inhabits the water area of the riverbed depression non-uniformly, both horizontally and vertically. The density of fish in the horizons of the investigated water area is distributed in descending order: pelagic - 105 sp./ha, bottom - 61 sp./ha, surface - 18 sp./ha. The features of the taxonomic distribution of fish are the following: in the surface horizon there are not found percid species and non-identified fish, their shares are decreasing from the bottom to pelagic horizons. The groups of cyprinids and whitefish-pike fish are registered throughout the water column of the riverbed depression: their shares increase from the bottom to the surface. The uneven distribution of different taxonomic fish groups in the investigated water area can be explained by the ecological features of different species in winter, as well as their trophic-defensive behavior.

scholarly journals LOCALITY OF FORMING WINTERING RIVERBED DEPRESSION IN IRTYSH RIVER

2020 ◽  
Vol 2020 (4) ◽  
pp. 7-21
Author(s):  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Water Area ◽  
Taxonomic Composition ◽  
Fish Density ◽  
Endangered Fish ◽  
Rational Use ◽  
Biological Resources ◽  
Control Section ◽  
Irtysh River ◽  
Riverbed Depression ◽  
The Irtysh River

The article describes a new locality of the formed wintering riverbed depression discovered in the erosion zone of the isthmus of conjugate meanders of the Irtysh river for the rational use and effective protection of aquatic biological resources in places of their concentration in the Irtysh river basin (Western Siberia, the Russian Federation. The morphology of the riverbed depression was mapped (relief and bathymetric maps). The maximum depths in the channel depression exceeded 27 m. The channel depression and 4 control river sections were studied. The analysis of hydroacoustic surveys showed that in the wintering riverbed depression there is, according to the statistical data, higher fish density compared to the control areas: in the water area of the riverbed depression the average fish density made 4 524 species/ha, in the control sections 245-2091 sp./ha. The cluster analysis based on the fish density and the size-taxonomic composition of the ichthyofauna has revealed that the riverbed depression is being separated into a cluster, but at the same time goes to the control section No. 4, which is located downstream, where further erosion of the river channel is registered. In this regard, the minimum protection zone of the wintering channel depression should include the water area of the channel depression and the water area of control section No. 4. In the water areas of the riverbed depression and control sections in the spring period, cyprinids dominate - up to 65% of the total number of fish, percids are represented to a lesser extent - 36.76%, coregonids and pikes - up to 18.18, sturgeons - up to 9.31%. The given locality of the wintering riverbed depression must be included in the list of protected river sections of the Fishing Rules for the West Siberian fishery basin for developing the effective strategy for the protection, restoration and rational use of aquatic biological resources, including rare and endangered fish species of the Irtysh River and the whole Ob-Irtysh basin

scholarly journals DIMENSIONAL AND TAXONOMIC STRUCTURE OF FISH POPULATION OF THE KONDINSKAYA RIVERBED DEPRESSION

2018 ◽  
pp. 25-32
Author(s):  
Andrey Aleksandrovich Chemagin
Keyword(s):  
Vertical Distribution ◽  
Water Column ◽  
Research Work ◽  
Fish Population ◽  
Water Area ◽  
Taxonomic Structure ◽  
Sonar System ◽  
Size Groups ◽  
Hydroacoustic Survey ◽  
Riverbed Depression

On the basis of modern hydroacoustic techniques the article presents features of the dimensional-taxonomic structure and vertical distribution of fish in the water area of one of the largest riverbed depressions in the lower reaches of the Irtysh river - Kondinskaya (Khanty-Mansiysky district, Tyumen region, Russia). There have been analyzed the conditioned water column horizons: from the surface to the bottom < 10 m, 10-20 m, 20-30 m, > 30 m. Maximum depth of the riverbed in the studied period exceeded 43 m. Research work was done by software-hardware sonar system AsCor. To perform hydroacoustic survey from the small boat in the investigated water area there were made displacements on a grid of transects (in zigzags). Recorded information of the hydroacoustic survey was processed in the laboratory using special software programs AsCor and Taxonomy which enable remote dimensional-taxonomic identification of fish with calculation of their density and number. It has been established that in each subsequent depth horizon the proportion of planktivorous fish (Cyprinidae) decreased in direction from the surface to the bottom; the proportion of predatory fishes (Percidae, Coregonidae, Esocidae), and a group of unidentified fishes (Acipenseridae, Lotidae), on the contrary, increased. The features of vertical distribution and taxonomic structure in the water column of the riverbed depression is an element of the survival strategy, primarily for juveniles of planktivorous species. More than 90% of fish from the total recorded population are concentrated at depths up to 20 m. In the research period among the fish population of the riverbed depression cyprinids dominated, in the size groups there prevailed individuals with body lengths up to 15 cm.

scholarly journals Numerical investigation of the Arctic ice-ocean boundary layer; implications for air-sea gas fluxes

2016 ◽  
Author(s):  
A. Bigdeli ◽  
B. Loose ◽  
S. T. Cole
Keyword(s):  
Sea Ice ◽  
Water Column ◽  
Mixed Layer ◽  
Mixed Layer Depth ◽  
The Arctic ◽  
Layer Depth ◽  
Near Surface ◽  
Resolution Model ◽  
Simplifying Assumptions ◽  
Vertical Spacing

Abstract. In ice-covered regions it can be challenging to determine air-sea exchange – for heat and momentum, but also for gases like carbon dioxide and methane. The harsh environment and relative data scarcity make it difficult to characterize even the physical properties of the ocean surface. Here, we seek a mechanistic interpretation for the rate of air-sea gas exchange (k) derived from radon-deficits. These require an estimate of the water column history extending 30 days prior to sampling. We used coarse resolution (36 km) regional configuration of the MITgcm with fine near surface vertical spacing (2 m) to evaluate the capability of the model to reproduce conditions prior to sampling. The model is used to estimate sea-ice velocity, concentration and mixed-layer depth experienced by the water column. We then compared the model results to existing field data including satellite, moorings and Ice-tethered profilers. We found that model-derived sea-ice coverage is 88 to 98 % accurate averaged over Beaufort Gyre, sea-ice velocities have 78 % correlation which resulted in 2 km/day error in 30 day trajectory of sea-ice. The model demonstrated the capacity to capture the broad trends in the mixed layer although with a bias and model water velocities showed only 29 % correlation with actual data. Overall, we find the course resolution model to be an inadequate surrogate for sparse data, however the simulation results are a slight improvement over several of the simplifying assumptions that are often made when surface ocean geochemistry, including the use of a constant mixed layer depth and a velocity profile that is purely wind-driven.

Contribution of Gammarus lacustris to phosphorus recycling in a fishless alpine lake

1999 ◽  
Vol 56 (9) ◽  
pp. 1679-1686 ◽  
Author(s):  
Frank M Wilhelm ◽  
Jeff J Hudson ◽  
David W Schindler
Keyword(s):  
Water Column ◽  
Vertical Migration ◽  
Mountain Lakes ◽  
Plankton Community ◽  
Alpine Lake ◽  
Gammarus Lacustris ◽  
Benthic Pelagic Coupling ◽  
Phosphorus Recycling ◽  
Planktonic Community ◽  
Total P

We estimated the net P transport by Gammarus lacustris from the benthic to pelagic regions of a fishless alpine lake and compared it with P regeneration by the entire plankton community. Gammarus lacustris released between 5.2 and 18.1 ng P·L-1·h-1 (adults only and adults plus immatures, respectively) in the pelagic region during nighttime vertical migration. Additional P released into and removed from the water column due to predation on zooplankton was estimated at 1.87 and 2.3 ng P·L-1·h-1, respectively. The net daily regeneration of 52.2-181.4 ng P·L-1·day-1 by the G. lacustris population represented 9.5-32.9% of the total P regenerated by the planktonic community. The majority of the P released by G. lacustris represents "new" P to the pelagic zone because it originated in sediments. We conclude that G. lacustris can represent an important link in benthic-pelagic coupling in oligotrophic mountain lakes.

scholarly journals Radiocesium in the Taiwan Strait and the Kuroshio east of Taiwan from 2018 to 2019

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wei-Jen Huang ◽  
Ming-Ta Lee ◽  
Kuei-Chen Huang ◽  
Kai-Jung Kao ◽  
Ming-An Lee ◽  
...  
Keyword(s):  
Water Column ◽  
Surface Waters ◽  
Half Life ◽  
North Pacific Ocean ◽  
Taiwan Strait ◽  
Depth Range ◽  
Near Surface ◽  
Activity Concentrations ◽  
The Taiwan Strait ◽  
The Kuroshio

AbstractThe release of anthropogenic radiocesium to the North Pacific Ocean (NPO) has occurred in the past 60 years. Factors controlling 137Cs (half-life, 30.2 year) and 134Cs (half-life, 2.06 year) activity concentrations in the Kuroshio east of Taiwan and the Taiwan Strait (latitude 20° N–27° N, longitude 116° E–123° E) remain unclear. This study collected seawater samples throughout this region and analyzed 134Cs and 137Cs activity concentrations between 2018 and 2019. A principal component analysis (PCA) was performed to analyze the controlling factors of radiocesium. Results of all 134Cs activity concentrations were below the detection limit (0.5 Bq m−3). Analyses of water column 137Cs profiles revealed a primary concentration peak (2.1–2.2 Bq m−3) at a depth range of 200–400 m (potential density σθ: 25.3 to 26.1 kg m−3). The PCA result suggests that this primary peak was related to density layers in the water column. A secondary 137Cs peak (1.90 Bq m−3) was observed in the near-surface waters (σθ = 18.8 to 21.4 kg m−3) and was possibly related to upwelling and river-to-sea mixing on the shelf. In the Taiwan Strait, 137Cs activity concentrations in the near-surface waters were higher in the summer than in the winter. We suggest that upwelling facilitates the vertical transport of 137Cs at the shelf break of the western NPO.

scholarly journals CHARACTERISTIC OF HARD TO IDENTIFY GENUS ACIPENSER SPECIES IN THE IRTYSH RIVER

2018 ◽  
pp. 90-98 ◽  
Author(s):  
Andrey Stepanovich Aldokhin ◽  
Gleb Igorevich Volosnikov
Keyword(s):  
Water Area ◽  
Bone Plates ◽  
Similar Species ◽  
Summer Period ◽  
Sturgeon Species ◽  
Irtysh River ◽  
June July ◽  
The Irtysh River

In the summer period (June-July) of 2018 on the Irtysh river (the Tobolsk region) in the control catches of sterlet there were found specimens with pronounced differences from individuals inhabiting this water area. Differences were found in the form of bone plates and linear-weight characteristics. Later, local fishermen reported on many cases of specimens having the above differences. Reports about the similar species came from the Uvat region. In order to establish the belonging of these individuals to a particular family there have been investigated meristic features which are considered diagnostic for sturgeon species, as well as for hybrids. In the result of the study there was made a conclusion about belonging of these specimens to the genus Acipenser and, most likely, to the sterlet species.

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