Taxonomic Composition and Seasonal Changes of Fish Larvae
Assemblages in Coastal Waters of Muscat, Sea of Oman
1Nadir M. Al-Abri, 2Sergey A. Piontkovski, 3Mahnaz Rabbaniha, 2Khalid Al-Hashmi and 1Tatyana Chesalina
1Marine Science and Fisheries Center, Muscat, Sultanate of Oman
2College of Agricultural and Marine Sciences, Sultan Qaboos University, P.O. Box 34, Al-Khod 123, Sultanate of Oman
3Iranian Fisheries Research Organization, P.O. Box 14155-6116, Tehran, Iran
Fish landings and Oman shelf area
Sergey A. Piontkovski1, H.E. Hamed S. Al-Oufi2, and Nadir M. Al-Abri2
1Sultan Qaboos University, College of Agricultural and Marine Sciences, Dpt. of Marine Science and Fisheries.
2 Ministry of Agriculture and Fisheries Wealth. PO 467, Muscat 113.
Sultanate of Oman.
Data from five field surveys carried out along the shelf in the 20-250m depth range and historical data on artisanal fishery were analyzed. A positive linear relationship between the demersal fish biomass and the shelf area was pronounced for a certain (intermediate) stratum only: 50-100m. No statistical link was found for the strata above it (25-50m) and beneath it (100-150m and 150-250m). The pronounced one was associated with the low boundary of the oxygen minimum zone impinging on the shelf. Annual landings of demersal fishes in the region with the largest shelf area exceeded landings in the region with the smallest area by as much as 1.6 times. The ratio of small pelagic to demersal fish landings decreased as a factor of 10, from small to large shelf areas.
Fish landings; Arabian Sea; continental shelf; oxygen minimum zone; Oman
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
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