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Subsurface algal blooms of the northwestern Arabian Sea Subsurface algal blooms of the northwestern Arabian Sea

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Date added: 03/06/2017
Date modified: 03/06/2017
Filesize: 1.76 MB
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Subsurface algal blooms of the northwestern Arabian Sea

Sergey A. Piontkovski1,*, Bastien Y. Queste2, Khalid A. Al-Hashmi1,
Aisha Al-Shaaibi1, Yulia V. Bryantseva3, Elena A. Popova4

1College of Agricultural and Marine Sciences, Sultan Qaboos University, PO Box 34, Al-Khod 123, Sultanate of Oman
2Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich NR4 7TJ, UK
3M.G. Kholodny Institute of Botany, 2 Terechenkovskaya Str., Kiev 01030, Ukraine
4Institute of Marine Biological Research, 2 Nakhimov Prospect, P.O. Box 229011, Russia

ABSTRACT
In situ plankton sampling, combined with remotely sensed and ocean Seaglider
observations, provided insight into the termination of the winter monsoon bloom and subsequent evolution into a subsurface fluorescence maximum in the northwestern Arabian Sea. This sub - surface maximum gradually descended, presenting increased fluorescence between 25 and 55 m depth during the spring inter-monsoon season. Species diversity decreased by half within the deep fluorescence maximum relative to the bloom. The dinoflagellate Noctiluca scintillans dominated by biomass in all samples collected from the depth of the subsurface fluorescence maximum. We show that the subsurface algal bloom persists throughout inter-monsoon seasons,
linking algal blooms initiated during the southwest and northeast monsoons. In situ samples showed a net decrease in Noctiluca cell size, illustrating a shift towards a deep chlorophyll maximum adapted community, but did not exhibit any increases in chlorophyll-containing endo - symbionts. We propose that the plankton biomass and estimates of the northwestern Arabian Sea productivity are much greater than estimated previously through remote sensing observations, due to the persistence, intensity and vertical extent of the deep chlorophyll maximum which— using remote means—can only be estimated, but not measured.

KEY WORDS: Algal blooms · Chlorophyll a · Zooplankton

Decadal changes of the Western Arabian sea ecosystem Decadal changes of the Western Arabian sea ecosystem

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Date added: 03/14/2016
Date modified: 03/14/2016
Filesize: 2.25 MB
Downloads: 576
Decadal changes of the Western Arabian sea ecosystem
Sergey A. Piontkovski1, Bastien Y. Queste2
1College of Agricultural and Marine Sciences, Sultan Qaboos University, Al-Khod 123, P.O. Box 34, Muscat, Sultanate of Oman
2Centre for Ocean and Atmospheric Sciences, University of East Anglia, Norwich, Norfolk NR4 7TJ, UK

Abstract
Historical data from oceanographic expeditions and remotely sensed data on outgoing longwave radiation, temperature, wind speed and ocean color in the western Arabian Sea (1950-2010) were used to investigate decadal trends in the physical and biochemical properties of the upper 300 m. 72 % of the 29,043 vertical profiles retrieved originated from USA and UK expeditions. Increasing outgoing longwave radiation, surface air temperatures and sea surface temperature were identified on decadal timescales. These were well correlated with decreasing wind speeds associated with a reduced Siberian High atmospheric anomaly. Shoaling of the oxycline and nitracline was observed as well as acidification of the upper 300 m. These physical and chemical changes were accompanied by declining chlorophyll-я concentrations, vertical macrofaunal habitat compression, declining sardine landings and an increase of fish kill incidents along the Omani coast.

Keywords
Arabian Sea,Fish landings,Chlorophyll-a,Sea surface temperature

Mesozooplankton of the Omani shelf Mesozooplankton of the Omani shelf

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Date added: 09/25/2015
Date modified: 09/25/2015
Filesize: 3.97 MB
Downloads: 1144
Mesozooplankton of the Omani shelf: taxonomy, seasonality, and spatial distribution
Sergey A. Piontkovski, Asyla Al-Mawali, Ahlam Al-Kharusi, WardalMuna Al- Manthri, Sharon Smith & Elena Popova

The total zooplankton biomass was determined for 216 samples collected during seasonal surveys onboard a research vessel. Some of these samples were processed to the level of species. In 2007–2008, the Omani shelf was populated by a highly productive epipelagic plankton community. The chlorophyll-a concentration was high throughout the seasonal cycle and likewise the zooplankton biomass, where seasonal values varied from 543 to 723 mg m-3. Spatial distribution of zooplankton biomass over shelf waters was highly heterogeneous, with maximal heterogeneity observed during the South-west Monsoon. The mean biomass and size structure of the zooplankton community did not exhibit statistically significant seasonal changes. On the species level, seasonal changes dealt with a massive appearance of the copepod Calanoides carinatus s.f. in shelf waters, to which organisms migrated from the deep, during the South-west Monsoon.
The population represented mainly by c4 and c5 copepodite stages ascending to upper layers during its ontogenetic migration has occupied the entire Omani shelf area. However, this migration did not contribute markedly to seasonal variation of the total zooplankton biomass.

Seasonal variability of size-classes of phytoplankton biomass in a sub-tropical embayment Seasonal variability of size-classes of phytoplankton biomass in a sub-tropical embayment

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Date added: 04/27/2015
Date modified: 04/29/2015
Filesize: 530.18 kB
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Seasonal variability of size-classes of phytoplankton biomass in a sub-tropical embayment, Muscat, Sea of Oman
Al-Hashmi K.1; Claereboudt M.1; Piontkovski S.1; Al Azri A.1; Amin S.M.N.2
1-College of agricultural and marine sciences, Sultan Qaboos university, P.O.Box: 34, Al-Khod
123, Sultanate of Oman.
2-Department of aquaculture, faculty of agriculture, university of Malaysia,43400. Serdang, Selangor, Malysisa

The contribution of three different cell size classes of picoplankton: 0.74-2 μm, nanoplankton:2–20 μm and microplankton, >20μm of the phytoplankton population and their relationship to environmental conditions were studied over two annual cycles at one station in Bandar Khyran Bay, Sea of Oman, from May 2006 to August 2008.

Dynamics of potentially harmful phytoplankton in a semi-enclosed bay in the Sea of Oman Dynamics of potentially harmful phytoplankton in a semi-enclosed bay in the Sea of Oman

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Date added: 04/27/2015
Date modified: 04/27/2015
Filesize: 1.75 MB
Downloads: 1870
Dynamics of potentially harmful phytoplankton in a semi-enclosed bay in the Sea of Oman
Khalid A Al-Hashmi 1, Sharon L Smith 2, Michel Claereboudt 1,Sergey A Piontkovski 1, Adnan Al-Azri 1

1 College of Agricultural and Marine Sciences, Sultan Qaboos
University, P.O. Box: 34, Al-Khod
123, Sultanate of Oman.
2 Rosenstiel School of Marine & Atmospheric Science, University
of Miami, 4600 Rickenbacker
Causeway, Miami, Florida 33149.
The dynamics of potentially harmful phytoplankton in relation to environmental parameters was investigated in the semi-enclosed Bay of Bandar Khayran (Sea of Oman) from April 2006 through April 2011. In total, 24 potentially harmful algal species were identified, including 11 species of dinoflagellates and eight species of diatoms.
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General contact:   Prof. Sergey Piontkovski spiontkovski@gmail.com
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