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Seasonal and Interannual Changes of Indian Oil Sardine, Sardinella longiceps Landings in the Governorate of Muscat (the Sea of Oman)

SERGEY A. PIONTKOVSKI, HAMED S. AL-OUFI, and SAUD AL-JUFAILI

ABSTRACT
Monthly data on Muscat’s landings of the Indian oil sardine, Sardinella longiceps, along with 23 environmental parameters ( sea surface temperature, temperature of the mixed layer, wind speed, kinetic energy of mesoscale eddies, concentration of nitrates, dissolved oxygen, chlorophyll-a, abundance of phytoplankton, zooplankton, and several others) were analyzed for the period 1994–2011. Seasonal changes were associated with the time of t h e winter (Northeast) monsoon, with maximal landings in February. The multiple regression analysis of the statistically signifi cant variables selected through the Principal Component Analysis has implied that 51% of seasonal variability in sardine landings might be approximated by the seasonal variations of the zonal component of wind speed and chlorophyll-a concentration in the coastal and open-sea regions. In terms of interannual changes, sardine landings exhibited a declining trend from 2001 to 2011 (the time covered by the most complete data set). Rising sea temperature, thermal stratifi cation of the water column, and the trophic pressure imposed on sardine populations by large pelagic predators (talang queenfi sh, Scomberoides commersonnianus; kingfi sh, Scomberomorus commerson; longtail tuna, Thunnus tonggol; and some others) might be the factors mediating this trend.

Variability of dinoflagellates and diatoms in the surface waters of Muscat, Sea of Oman: comparison between enclosed and open ecosystem

Khalid A Al-Hashmi(1)*, Joaquim Goes(2), Michael Claereboudt (1), Sergey A. Piontkovski (1), Adnan Al-Azri (1), Sharon L Smith (3)
1-Khalid A Al-Hashmi* (Corresponding author); College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O.Box: 34, Al-Khod 123, Sultanate of Oman. This email address is being protected from spambots. You need JavaScript enabled to view it.
2-Joaquim Goes; Lamont Doherty Earth Observatory, Columbia University, Palisades, NY 10964, USA This email address is being protected from spambots. You need JavaScript enabled to view it.
1-Michael Claereboudt; College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O.Box: 34, Al-Khod 123, Sultanate of Oman. This email address is being protected from spambots. You need JavaScript enabled to view it.
1-Sergey A. Piontkovski; College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O.Box: 34, Al-Khod 123, Sultanate of Oman. This email address is being protected from spambots. You need JavaScript enabled to view it.
1-Adnan Al-Azri; College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O.Box: 34, Al-Khod 123, Sultanate of Oman.  This email address is being protected from spambots. You need JavaScript enabled to view it.
3-Sharon L Smith;The Rosenstiel School, University of Miami, 4600 Rickenbacker Causeway, Miami, FL 33149 USA. This email address is being protected from spambots. You need JavaScript enabled to view it.

ABSTRACT
We investigated the distribution patterns of phytoplankton species over a one year period (from April 2010 to February 2011) at an open ocean location off the coast of Muscat, Sea of Oman (OFF) and the other at Bandar Khayran (BK), a semi enclosed bay located downstream of the southeastward Sea of Oman coastal current. Although these two locations come under the influence of the semi-annually reversing monsoons, and experience nutrient influxes associated with the southwest (SWM, June-Sept.) and the northeast monsoons (NEM, Nov.-Feb.), they are hydrographically distinct. At both stations, a total of 133 phytoplankton taxa were identified and quantified over the sampling period. The two stations showed higher phytoplankton abundance, higher diversity and higher chlorophyll concentrations during the SWM and NEM seasons, a reflection of phytoplankton populations responding to injection of nutrients during these two seasons. Phytoplankton communities at both at BK and OFF were dominated by dinoflagellates and showed no significant differences in dinoflagellate community composition. In addition, no clear trend of dinoflagellate or diatom species succession was observed during the study period. Among the dinoflagellate population, Prorocentrum minimum, Gymnodinium sp., Scrippsiella trochoidea, Gymnodinium simplex and the mixotroph Noctiluca scintillans. On the other hand, Lauderia punctata, Bacteriastrum elongatum and Paralia moniliformis, Chaetoceros spp. Guinardia striata and Thalassiosira spp. were the most dominant diatoms.
Key words: Dinoflagellate, diatoms, monsoon, upwelling, Sea of Oman, Arabian Sea, coastal environments

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