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Relationship between Algal Blooms, Fish Kill Incidents, and Oxygen Depletions Relationship between Algal Blooms, Fish Kill Incidents, and Oxygen Depletions

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Date added: 02/16/2013
Date modified: 02/19/2013
Filesize: 1.21 MB
Downloads: 7435
The Relationship between Algal Blooms, Fish Kill Incidents, and Oxygen Depletions along the Omani Coast
S.A. Piontkovski1), H.M.H. Al-Gheilani2), B. Jupp3), Y.V.B. Sarma1), and A.R. Al-Azri1)
1) Sultan Qaboos University, CAMS,PO Box 34, Al-Khod 123, Sultanate of Oman
2) Marine Science and Fisheries Center, Ministry of Agriculture and Fisheries,
P.O. Box 467, Muscat 113, Sultanate of Oman
3) GEO-Resources Consultancy, P.O. Box 175, Mina Al Fahal, Muscat 116
Sultanate of Oman

A persistence of hypoxia is a common feature for the Sea of Oman, and the western Arabian Sea. By using historical data complemented by ongoing measurements, the relationship between the frequency of harmful algal blooms, fish kill incidents, and oxygen depletions, was investigated. In the Sea of Oman, the seasonal pattern exhibited a tendency of fish kill incidents to increase, from January to November. In the western Arabian Sea, the pattern was different- maximal occurrence of fish kill incidences was observed in December and January.
In 1988-2011, the number of harmful algal blooms accompanied by fish kills was 4 times higher for the Sea of Oman (N= 91) compared to the Arabian Sea coast (N= 22), whereas the total number of fish kill incidents was about the same (22 versus 25). This means that the Arabian Sea coast faced more frequent harmful blooms than the Sea of Oman. The Sea of Oman coastal time series of the dissolved oxygen concentration implied a steady decline throughout the year, from January to December.
The fish kill incidents in this region were mainly driven by oxygen depletions, whereas in
the Arabian Sea these incidents were mediated by the harmful algal blooms along with the oxygen depletions. In analyzing the Omani coast as a whole, the Ridge Multiple Regression Analysis implied the dissolved oxygen concentration and monthly occurrence of algal blooms as the two variables explaining 75% of the seasonal variations in fish kill incidents.

Coastal upwellings and Mesoscale Eddies of the Western Arabian Sea Coastal upwellings and Mesoscale Eddies of the Western Arabian Sea

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Date added: 07/03/2013
Date modified: 07/03/2013
Filesize: 2.33 MB
Downloads: 4213
Coastal upwellings and Mesoscale Eddies of the
Western Arabian Sea: Some Biological Implications

S.A. Piontkovski and S. Al-Jufaili
Sultan Qaboos University, CAMS,
PO Box 34, Al-Khod 123,
Sultanate of Oman

Satellite derived (SeaWIFS, MODIS, TOPEX/Poseidon, and Jason) chlorophyll-a concentration, sea surface heights, sea surface temperature, data on vertical profiles of temperature and salinity from the ARGO drifting floats, wind speed, the Dipole Mode Index, and historical data on sardine landings were employed, to analyze physical-biological coupling in the western Arabian Sea which is known for its vigorous eddy field affecting
characteristics of biological productivity.
Summer and winter monsoons impose different modes of mesoscale variability. In summer, the East Arabian Current along with the currents of the Arabian Sea interior generates a dense field of eddies, where as in winter, eddies become less developed and less numerous. Therefore, the chlorophyll distribution is more heterogeneous spatially and more variable temporally during summer monsoon. Interannual changes of eddy field bear footprints of the impact of basin-scale atmospheric anomaly (the Indian Ocean Dipole). Spatial-temporal characteristics of the eddy field are valuable tools in understanding seasonal and interannual fluctuations of sardine landings contributing ~ 50% to the fishery in the region.

Mesoscale eddies and variability of chlorophyll-a in the Sea of Oman Mesoscale eddies and variability of chlorophyll-a in the Sea of Oman

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Date added: 03/01/2012
Date modified: 03/01/2012
Filesize: 447.57 kB
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Mesoscale eddies and variability of chlorophyll-a in the Sea of Oman
SERGEY A. PIONTKOVSKI*, NIKOLAY P. NEZLIN, ADNAN AL-AZRIand KHALID AL-HASHMI
Department of Marine Science and Fisheries, Sultan Qaboos University, Al-Khod 123, Sultanate of Oman
Southern California Coastal Water Research Project, Costa Mesa, CA 92626, USA

Satellite-derived (TOPEX/Poseidon, Jason-1, Jason-2, SeaWIFS (Sea-Viewing Wide Field-of-View Sensor) and MODIS (Moderate Resolution Imaging Spectroradiometer) Aqua) weekly and monthly products for sea surface height, sea surface temperature (SST) and chlorophyll-a (CHL) concentration were used to analyse the trends of physical–biological coupling. In the variability of chlorophyll, no interannual trends were found for the Sea of Oman (1997–2008). However, the variation of chlorophyll within the annual cycle has increased. A similar tendency was evaluated for the variability of the energy of mesoscale eddies. Themedian level of kinetic energy and the coefficient of variation of this energy within the annual cycle both increased from 1997 through 2008.

Seasonal and interannual variability of chlorophyll-a in the Gulf of Oman Seasonal and interannual variability of chlorophyll-a in the Gulf of Oman

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Date added: 01/21/2012
Date modified: 01/21/2012
Filesize: 634.7 kB
Downloads: 3879
Seasonal and interannual variability of chlorophyll-a in the Gulf of Oman compared to the open Arabian Sea regions
SERGEY PIONTKOVSKI*, ADNAN AL-AZRI and KHALID AL-HASHMI
Department of Marine Science and Fisheries,
College of Agricultural and Marine Sciences,
Sultan Qaboos University, CAMS, P.O. 34, Al-Khod 123,
Sultanate of Oman

Field sampling, remote sensing and modelling were employed to understand the seasonal and interannual changes of chlorophyll-a concentrations in the Gulf of Oman in comparison to open sea regions. In these regions, maximal chlorophyll concentrations were reported during the summer monsoon (with peaks in June and August), while in the Gulf of Oman, the chlorophyll maximum was observed during the winter monsoon (February–March). From 1997 through to 2008, the interannual variability in chlorophyll-a concentrations in the Gulf of Oman has not exhibited pronounced trends and neither have the other two (oceanic) regions in the western Arabian Sea. However, an increase of the annual variation in chlorophyll concentrations over the years was noticed. The diatom biomass decreased two-fold from 1997 to 2007. Nitrate concentration and mixed-layer depth also declined. In comparison to the seasonal blooms driven in the Gulf of Oman by the dinoflagel- late Noctiluca scintillans, the year 2008 was markedly different. The summer bloom was shifted to September; it was gradually extended in time and formed by the other species. An applicability of the concept of ecosystem regime shift is discussed.

Seasonal Changes of Chlorophyll a and Environmental Characteristics in the Sea of Oman Seasonal Changes of Chlorophyll a and Environmental Characteristics in the Sea of Oman

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Date added: 12/31/2010
Date modified: 01/04/2011
Filesize: 811.73 kB
Downloads: 3312

Al-Hashmi, Khalid A. Claereboudt*, Michel R. Al-Azri, Adnan, R. Piontovski, Sergey. A.
Sultan Qaboos University, Department Marine Science and Fisheries College Agricultural and Marine Sciences, Box 34
Al-Khod 123 Sultanate of Oman

Monthly estimates of chlorophyll a, temperature, salinity, and nutrients were collected through sampling at two stations from January 2001 to January 2002, in and near Bandar Al-Khyran, the largest semi-enclosed bay on the southern coast of the Sea of Oman.

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