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Interannual changes of the Arabian Sea productivity

Department of Marine Science and Fisheries, Sultan Qaboos University, Al-Khod, Sultanate of Oman

Inter-annual changes in temperature and chlorophyll a across the Arabian Sea (subdivided into 61 2-degree regions) were analysed. For each 2-degree region, from appropriate databases, remotely sensed chlorophyll a, sea surface temperature, and wind speed time series were retrieved. Spatial and temporal trend analysis showed physical - biological oscillations with dominant periods of 12 and 6 months (reflecting the seasonality of monsoonal winds) with a globally warming trend, but no overall increase in chlorophyll during the period 1997 - 2009. Variation coefficients of the inter-annual time series of chlorophyll a implied high variability in western regions of the sea in comparison to eastern regions. The basin-wide maps of chlorophyll distribution did not show the enlargement of the productive area over time and overall, not only did the Arabian Sea not get more productive, but several regions in its eastern basin showed a decline in chlorophyll a concentration.

Key words: Arabian Sea, chlorophyll a, global changes, marine ecosystems

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

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.

Penilia avirostris: Regional and Global Patterns of Seasonal Cycles

S.A. Piontkovski1, S. Fonda-Umani2, A. De Olazabal3 and A.D. Gubanova4
1Sultan Qaboos University, CAMS, PO 34, Al-Khod 123, Sultanate of Oman
2Department of Life Sciences, University of Trieste,
v. Valerio 28/1 34123 Trieste, Italy
3Department of Biological Oceanography, OGS, v. Piccard, 42, Italy
4Institute of Biology of the Southern Seas, 2 Nakhimov Pr.,
Sevastopol 99011, Ukraine
*Corresponding Author E-mail: This email address is being protected from spambots. You need JavaScript enabled to view it.

Seasonal cycles of the Penilia abundance were compared, over five coastal regions-the north-western part of the Black Sea (Sevastopol Bay), the northern
part of the Adriatic Sea (Gulf of Trieste), the north-eastern Atlantic (Vigo coast), the north-western Mediterranean basin (Barcelona coast), and the
north-western part of the Arabian Sea (the Gulf of Oman). Satellite derived monthly data were used, to analyze coupling between the Penilia abundance,
sea surface temperature, and chlorophyll a concentration over these regions. Two types of seasonal dynamics were noticed: (1) a unimodal type of population dynamics with one peak lasting 3-4 months in summer to fall (in Vigo, Sevastopol, and Trieste regions) and (2) all year round persisting
population in subtropical highly productive waters of the Arabian Sea (Gulf of Oman). A regional link between abundance and temperature was also reflected
by the global geography of the Penilia habitats. As far as the global aspect is concerned, a general relationship representing the abundance as the linear function of two environmental variables-sea surface temperature and chlorophyll a concentration was proposed.

Keywords: Zooplankton; Arabian Sea; Black Sea; Mediterranean Sea

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