Environmental variables and their interaction effects on chlorophyll-a in coastal waters of the southern Caspian Sea: assessment by multiple regression grey models

Abstract. Phytoplankton as chlorophyll-containing organisms is the first step of production in most marine processes and food chains. Nutrient enhancement in the seawater due to the discharge of agricultural, industrial, and urban wastes threatens the Caspian Sea environment. Increasing concentrations of chlorophyll-a in seawater, in reaction to the elevation of nutrient supply can have severely damaging effects on the marine environment of the Caspian. In this research, seasonal variability of the chlorophyll-a concentrations in the western part of the southern coastal waters of the Caspian Sea near Iranian coast was examined using field observations. The data showed that the most chlorophyll-a was found below the sea surface. The thermal stratification in water column and outflow of the Anzali Lagoon affect the chlorophyll-a concentrations in the region. Concentrations of chlorophyll-a were recorded in midsummer in a range of 0.2–3.4 mg m−3.

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Step-up multiple regression model to compute Chlorophyll a in the coastal waters off Cochin, southwest coast of India

Environmental Monitoring and Assessment ◽

10.1007/s10661-007-9829-5 ◽

2007 ◽

Vol 139 (1-3) ◽

pp. 217-226 ◽

Cited By ~ 7

Author(s):

K. K. Balachandran ◽

K. V. Jayalakshmy ◽

C. M. Laluraj ◽

Maheswari Nair ◽

Thresiamma Joseph ◽

...

Keyword(s):

Regression Model ◽

Multiple Regression ◽

Chlorophyll A ◽

Coastal Waters ◽

Multiple Regression Model ◽

Southwest Coast Of India ◽

Southwest Coast

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Estimating chlorophyll-A concentration in the Caspian Sea from MODIS images using artificial neural networks

Environmental Engineering Research ◽

10.4491/eer.2019.106 ◽

2019 ◽

Vol 25 (4) ◽

pp. 515-521

Author(s):

Siamak Boudaghpour ◽

Hajar Sadat Alizadeh Moghadam ◽

Mohammadreza Hajbabaie ◽

Seyed Hamidreza Toliati

Keyword(s):

Neural Networks ◽

Chlorophyll A ◽

Coastal Waters ◽

Caspian Sea ◽

Training Data ◽

The Caspian Sea ◽

Feed Forward ◽

Chlorophyll A Concentration ◽

Hidden Layer ◽

Mean Square Errors

Nowadays, due to various pollution sources, it is essential for environmental scientists to monitor water quality. Phytoplanktons form the end of the food chain in water bodies and are one of the most important biological indicators in water pollution studies. Chlorophyll-A, a green pigment, is found in all phytoplankton. Chlorophyll-A concentration indicates phytoplankton biomass directly. Therefore, Chlorophyll-A is an indirect indicator of pollutants, including phosphorus and nitrogen, and their refinement and control are important. The present study, Moderate Resolution Imaging Spectroradiometer (MODIS) satellite images were used to estimate the chlorophyll-A concentration in southern coastal waters in the Caspian Sea. For this purpose, Multi-layer perceptron neural networks (NNs) were applied which contained three and four feed-forward layers. The best three-layer NN has 15 neurons in its hidden layer and the best four-layer one has 5 in each. The three- and four- layer networks both resulted in similar root mean square errors (RMSE), 0.1(<math xmlns="http://www.w3.org/1998/Math/MathML"><mfrac><mrow><mi>μ</mi><mi>g</mi></mrow><mi>l</mi></mfrac></math>), however, the four-layer NNs proved superior in terms of R<sup>2</sup> and also required less training data. Accordingly, a four-layer feed-forward NN with 5 neurons in each hidden layer, is the best network structure for estimating Chlorophyll-A concentration in the southern coastal waters of the Caspian Sea.

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THE NUMBER AND QUALITATIVE CHARACTERISTICS OF FRY FISH IN SHALLOW COASTAL WATERS OF THE VOLGA IN THE SUMMER-AUTUMN PERIOD OF 2012

VESTNIK OF ASTRAKHAN STATE TECHNICAL UNIVERSITY SERIES FISHING INDUSTRY ◽

10.24143/2073-5529-2017-3-65-73 ◽

2017 ◽

pp. 65-73

Author(s):

Edward Vladimirovich Nikitin

Keyword(s):

Fish Species ◽

Coastal Waters ◽

Caspian Sea ◽

The Caspian Sea ◽

Volga River ◽

Commercial Fish ◽

Autumn Period ◽

Fish Juveniles ◽

Qualitative Characteristics ◽

Shallow Coastal Waters

Shallow coastal waters of the Volga river is a flooded feeding area for fish juveniles of nonmigratory fish species. There takes place annual downstream migration of fluvial anadromous fish species from spawning grounds of the Volga river to the Northern Caspian Sea. The most important factors determining the number and qualitative characteristics of fry fishes are the level of the Caspian Sea (currently having a tendency to the lowering), hydrological and thermal regimes of the Volga river. Researches were carried out in definite periods of time. In the summer-autumn period of 2012 fry fishes were presented by 19 species (13 of them were commercial species), which belonged to 9 families. The article gives data on all the commercial fish species. In the first decade of July the maximum number of fry fish was registered in the western part of the Volga outfall offshore - in box 247 (19.86 mln specimens/km2), in the eastern part - in box 142 (20.4 mln specimens/km2). The most populous were roach, red-eye, silver bream and bream; size-weight characteristics were better in the areas remoted from the Volga delta. In the third decade of July the quantitative indicators of fry fish on these areas decreased, size-weight characteristics greatly increased. In the second decade of October in the western part of the seaside there were registered increased pre-wintering concentrations of fish juveniles, their qualitative indicators increased, which is evidence to favorable feeding conditions in 2012.

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