scholarly journals Dependence of the Photosynthetic Quantum Yield on Phytoplankton Light Absorption: Equations for Assessing Primary Production in the Black Sea

2021 ◽  
Vol 28 (1) ◽  
Author(s):  
T. Ya. Churilova ◽  
V. V. Suslin ◽  
H. M. Sosik ◽  
◽  
◽  
...  
Keyword(s):  
Quantum Yield ◽  
Black Sea ◽  
Light Absorption ◽  
Euphotic Zone ◽  
The Black Sea ◽  
Absorption Coefficients ◽  
Phytoplankton Pigments ◽  
Photosynthetic Quantum Yield ◽  
Downwelling Irradiance

Purpose. Investigations were performed during a scientific cruise to characterize hydrophysical properties, chlorophyll a concentration, photosynthesis-irradiance curves, spectral light absorption coefficients by phytoplankton, and spectral quantum downwelling irradiance. From these results, the dependence of the photosynthetic quantum yield upon environmental factors was studied with the purpose of adapting an algorithm developed for the Baltic Sea so that it can be applied for the Black Sea. Methods and Results. Complex hydrophysical and biological studies were carried out at several depths within the euphotic zone. Spectral bio-optical parameters were measured in accordance with the latest NASA protocols (2018). Experiments to determine the photosynthesis-light relationship were performed under temperature and light conditions similar to those in situ. The quantum yield of photosynthesis was calculated from parameters of photosynthesis-light curves (photosynthesis efficiency, light saturation parameter) and the spectral light absorption coefficients by phytoplankton pigments. It was found out that the main photosynthetic characteristics of phytoplankton, including the maximum photosynthetic quantum yield and the fraction of phytoplankton absorption associated with photoprotective accessory pigments, varied with depth within the euphotic zone, due to phytoplankton acclimation to environment factors during the period of seasonal stratification. The relationship between the photosynthetic quantum yield and the quanta absorbed by photosynthetically active phytoplankton pigments was revealed. The results of this research made it possible to build on the approach developed for other regions and modify the equation for calculating the quantum yield to apply specifically for environmental conditions in the Black Sea. Conclusions. For the first time, comprehensive studies carried out in the Black Sea, including measurements of the photosynthesis-light dependence, spectral light absorption coefficients by phytoplankton and spectral downwelling irradiance as a function of optical depths within the euphotic zone, made it possible to reveal the equation for calculating photosynthetic quantum yield. This new equation can be applied for calculating primary production of the Black Sea using a spectral approach, based both on the results of in situ measurements and remote sensing data.

scholarly journals Dependence of the Photosynthesis Quantum Yield on Phytoplankton Light Absorption: Equations for Assessing Primary Production in the Black Sea

2021 ◽  
Vol 37 (1) ◽  
Author(s):  
T. Ya. Churilova ◽  
V. V. Suslin ◽  
H. M. Sosik ◽  
◽  
◽  
...  
Keyword(s):  
Quantum Yield ◽  
Primary Production ◽  
Black Sea ◽  
Light Absorption ◽  
Euphotic Zone ◽  
The Black Sea ◽  
Absorption Coefficients ◽  
Phytoplankton Pigments ◽  
Downwelling Irradiance

Purpose. Based on the results of the investigations that were performed during the scientific cruise and included the water hydrophysical characteristics, the chlorophyll a concentration, the photosynthesis-light dependences, the spectral light absorption coefficients by phytoplankton, and the spectral quantum downwelling irradiance, the dependence of the photosynthesis quantum yield upon the environmental factors was studied with the purpose of adaptation of the developed for the Baltic Sea approach for assessing the photosynthesis quantum yield, to the Black Sea. Methods and Results. Complex hydrophysical and biological studies were carried out at several depths within the photosynthesis zone. Spectral bio-optical parameters were measured in accordance with the modern NASA protocol (2018). The experiments on studying the photosynthesis-light relationship were performed under the temperature and light conditions close to the in situ ones. The quantum yield of photosynthesis was calculated based on the parameters of photosynthesis-light dependences (photosynthesis efficiency, light saturation parameter) and the spectral light absorption coefficients by phytoplankton pigments. It was found out that the main photosynthetic characteristics of phytoplankton including the photosynthesis maximum quantum yield and the portion of photoprotective accessory pigments in the total light absorption by phytoplankton varied with depth within the euphotic zone due to phytoplankton adaptation to the environment factors during the period of water seasonal stratification. The relationship between the photosynthesis quantum yield and the number of solar energy quanta absorbed by the photosynthetically active phytoplankton pigments was revealed. The results of the performed research allowed for modifying the equation for calculating the quantum yield for the Black Sea environment conditions according to the approach developed for the other water areas. Conclusions. For the first time, comprehensive studies carried out in the Black Sea and including the measurements of the photosynthesis-light dependences, the spectral light absorption coefficients by phytoplankton and spectral downwelling irradiance at particular optical depths within the euphotic zone enabled to reveal the equation for calculating the photosynthesis quantum yield, which could be applied for calculating primary production of the Black Sea using the spectral approach based both on the results of in situ measurements and the remote sensing data.

scholarly journals Bio-Optical Characteristics of the Black Sea Coastal Waters near Sevastopol: Assessment of the MODIS and VIIRS Products Accuracy

2021 ◽  
Vol 37 (2) ◽  
Author(s):  
E. Yu. Skorokhod ◽  
T. Ya. Churilova ◽  
T. V. Efimova ◽  
N. A. Moiseeva ◽  
V. V. Suslin ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Black Sea ◽  
Coastal Waters ◽  
Light Absorption ◽  
Ecological Monitoring ◽  
Optically Active ◽  
The Black Sea ◽  
Active Components ◽  
Chlorophyll A Concentration

Purpose. The purpose of the work is to evaluate accuracy of the satellite products for the coastal waters near Sevastopol, reconstructed by the standard algorithms based on the MODIS and VIIRS (installed at the artificial Earth satellites Aqua and Terra, and at Suomi NPP, respectively) data. Methods and Results. In situ sampling was carried out at the station (44°37'26" N and 33°26'05" E) located at a distance of two miles from the Sevastopol Bay. The chlorophyll a concentration was measured by the spectrophotometric method. The spectral light absorption coefficients by optically active components were measured in accordance with the current NASA protocol. The spectroradiometers MODIS and VIIRS Level 2 data with spatial resolution 1 km in nadir around the in situ station (44°37'26"±0°00'32" N and 33°26'05"±0°00'54" E) were used. The satellite products were processed by the SeaDAS 7.5.3 software developed in NASA. The research showed that the standard NASA algorithms being applied to the MODIS and VIIRS data, yielded incorrect values of the optically active components’ content in the Black Sea coastal waters near Sevastopol as compared to the data of in situ measurements in the same region: the satellite-derived “chlorophyll a concentration” was on average 1.6 times lower in spring, and 1.4 times higher in summer; the contribution of phytoplankton pigments to total light absorption at 443 nm was underestimated in 8.7 times; the light absorption by colored detrital organic matter was overestimated in 2.2 times. Conclusions. The NASA standard algorithms are inapplicable to calculating bio-optical indices in the coastal waters of the Black Sea near Sevastopol since they provide incorrect values of the satellite products (Ca-s, aph-s(443) and aCDM-s(443)). Operative ecological monitoring based on satellite data requires development of a regional algorithm taking into account the seawater optical features in the region and in the coastal zone, in particular.

scholarly journals Inter-Annual Variability of the Seawater Light Absorption in Surface Layer of the Northeastern Black Sea in Connection with Hydrometeorological Factors

2019 ◽  
Vol 7 (9) ◽  
pp. 326 ◽  
Author(s):  
Anna Yushmanova ◽  
Oleg Kopelevich ◽  
Svetlana Vazyulya ◽  
Inna Sahling
Keyword(s):  
Surface Layer ◽  
Black Sea ◽  
Light Absorption ◽  
Vertical Mixing ◽  
Field Studies ◽  
The Black Sea ◽  
Strong Wind ◽  
Science And Engineering ◽  
Main Factor

Data on the light absorption by seawater and its components are needed in many theoretical and practical aspects of marine science and engineering. However, up to now, there is a lack of such data for the northeastern part of the Black Sea. This article presents the data on light absorption measured by a portable integrated cavity absorption meter (ICAM) spectrophotometer in the Gelendzhik region of the Black Sea during field studies in June 2017 and 2018, together with other bio-optical and oceanographic data from in situ measurements and satellite observations. In 2018, the elevated values of the colored dissolved organic matter (CDOM) absorption in the surface layer were observed concurrently with high values of salinity, contradicting the idea of river runoff being the main CDOM source. The vertical profiles of salinity differed in 2017 and 2018, especially in shallow waters; in the upper layer, the salinity increased from 17.1 psu in 2017 to 17.8 psu in 2018, while the values of CDOM absorption increased from 0.10 to 0.16 m−1. The analysis of available hydrometeorological data pointed to intensive vertical mixing due to the strong wind forcing as a main factor in increasing values of both salinity and the CDOM absorption in the surface layer in 2018.

scholarly journals Bio-Optical Characteristics of the Black Sea Coastal Waters near Sevastopol: Assessment of the MODIS and VIIRS Products Accuracy

2021 ◽  
Vol 28 (2) ◽  
Author(s):  
E. Yu. Skorokhod ◽  
T. Ya. Churilova ◽  
T. V. Efimova ◽  
N. A. Moiseeva ◽  
V. V. Suslin ◽  
...  
Keyword(s):  
Chlorophyll A ◽  
Black Sea ◽  
Coastal Waters ◽  
Light Absorption ◽  
Ecological Monitoring ◽  
Optically Active ◽  
The Black Sea ◽  
Active Components ◽  
Chlorophyll A Concentration

Purpose. The purpose of the work is to evaluate accuracy of the satellite products for the coastal waters near Sevastopol, generated by the standard algorithms based on the MODIS and VIIRS (installed at the artificial Earth satellites Aqua and Terra, and at Suomi NPP, respectively) data. Methods and Results. In situ sampling was carried out at the station (44°37’26" N and 33°26’05" E) located at a distance of two miles from the Sevastopol Bay. The chlorophyll a concentration was measured by the spectrophotometric method. The spectral light absorption coefficients by optically active components were measured in accordance with the current NASA protocol. The spectroradiometers MODIS and VIIRS Level-2 data with spatial resolution 1 km in nadir around the in situ station (44°37’26"±0°00’32" N and 33°26’05"±0°00’54" E) were used. The satellite products were processed by the SeaDAS 7.5.3 software developed in NASA. The research showed that the standard NASA algorithms being applied to the MODIS and VIIRS data, yielded incorrect values of the optically active components’ content in the Black Sea coastal waters near Sevastopol as compared to the data of in situ measurements in the same region: the satellite-derived “chlorophyll a concentration” was on average 1.6 times lower in spring, and 1.4 times higher in summer; the contribution of phytoplankton to total light absorption at 443 nm was underestimated in 8.7 times; the light absorption by colored detrital matter was overestimated in 2.2 times. Conclusions. The NASA standard algorithms are inapplicable to calculating bio-optical indices in the coastal waters of the Black Sea near Sevastopol since they provide incorrect values of the satellite products (Ca-s, aph-s(443) and aCDM-s(443)). Operative ecological monitoring based on satellite data requires development of a regional algorithm taking into account the seawater optical features in the region and in the coastal zone, in particular.

scholarly journals A study of long-term changes in Black Sea ecosystems based on data assimilation of remote measurements in a numerical model

2019 ◽  
Vol 46 (1) ◽  
pp. 58-69
Author(s):  
V. L. Dorofeev ◽  
L. I. Sukhikh
Keyword(s):  
Black Sea ◽  
Marine Ecosystem ◽  
Three Dimensional ◽  
The Black Sea ◽  
Regular Grid ◽  
Remote Measurements ◽  
Biogeochemical Parameters ◽  
Color Scanner

Herein, we present a simulation of the dynamics of Black Sea ecosystems using a three-dimensional interdisciplinary model that assimilates satellite color scanner measurements. Calculations were performed for the fifteen years from 1998 and a set of 3-d biogeochemical fields of the Black Sea were generated on a regular grid with a discreteness time of 1 day. Analyses of core biogeochemical parameters of the marine ecosystem were then performed. The qualities of received fields were evaluated using comparisons with existing data from in situ measurements.

scholarly journals Ecological interrelations of Rapana venosa (Gastropoda: Muricidae) with ichthyofauna in the Black Sea

2016 ◽  
Vol 1 (4) ◽  
pp. 76-77
Author(s):  
I. P. Bondarev
Keyword(s):  
Black Sea ◽  
Marine Ecosystem ◽  
Fish Fauna ◽  
The Black Sea ◽  
Sandy Bottom ◽  
Rapana Venosa ◽  
New Information ◽  
Bottom Zone

Systematic monitoring of ecologically significant species – predatory mollusc Rapana venosa Valenciennes, 1846 populations – is an important part of the Black Sea monitoring. The study of the role of R. venosa in contemporary marine ecosystem is of considerable interest. In June-September 2015-2016 the study of consorting relations of rapana was conducted in situ with a parallel sampling by diver. In the course of research new information about the interaction of R. venosa with the fish fauna has been obtained. Of particular importance for fishes is the presence of rapana in the sandy bottom zone, where there are no natural shelters, and food resources are limited. The most important for the fish is the presence on the rapana shells of algal fouling and epiphyton. The shells of invader – R. venosa – and its fouling create additional opportunities for the survival of some fish fauna representatives juveniles of the Black Sea. The data obtained extend the concepts of ecological role of mollusc – invader R. venosa, as well as the ecology and ethology of several fish species.

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