NOPR Collection:

Sea level changes along the Saudi coast of the Arabian Gulf

Fri, 01 Sep 2000 00:00:00 GMT

Title: Sea level changes along the Saudi coast of the Arabian Gulf Authors: Sultan, S A R; Moamar, M O; El-Ghribi, N M; Williams, R Abstract: Sea level records over a period of 15 years (1980-1994) along the Saudi coast of the Arabian Gulf have been analyzed. The sea level changes, being dominated by a seasonal signal, are spatially coherent over the study area. The short term changes are characterized by large irregular amplitudes during winter, while summer variations are relatively small and uniform. An inverted barometer response close to the isostatic hypothesis (-1 cm mb^-1) holds for both short term and seasonalvariations. The study also reveals that over this particular period the sea level exhibits an increasing trend of 0.17 cm y^-1which is in agreement with the worldwide accepted value. Page(s): 191-200

Polonium-210 in bivalve molluscs of Gulf of Mannar, southeast coast of India

Fri, 01 Sep 2000 00:00:00 GMT

Title: Polonium-210 in bivalve molluscs of Gulf of Mannar, southeast coast of India Authors: Somasundaram, S S N; Hameed, P Shahul Abstract: This paper presents the concentration of ²¹⁰Po in five species of bivalve molluscs (Donax faba, Donax cuneatus, Scapharca inaequivalvis, Pinctada vulgaris and Perna indica) from Gulf of Mannar, southeast coast of India. The levels of ²¹⁰Po among the tested species ranged from 65.8 to 2,668.9 Bq kg-1. Analyses indicated that the soft tissues of the bivalves registered a higher level of ²¹⁰Po than the shells. Further, analyses also showed a non-uniformity in the distribution of ²¹⁰Po in the various internal organs. The concentration recorded in them maintained the following descending order: digestive glands> viscera> gills>foot>mantle> shell. It is evident that P. indica could be used as sentinel organism for ²¹⁰Po in the ambient waters. Page(s): 263-267

Tolerance of three marine microalgae to cryoprotectant dimethy sulfoxide, methanol and glycerol

Fri, 01 Sep 2000 00:00:00 GMT

Title: Tolerance of three marine microalgae to cryoprotectant dimethy sulfoxide, methanol and glycerol Authors: Joseph, Imelda; Panigrahi, A.; Chandra, P. Kishore Abstract: Studies on tolerance limit of cryoprotectants. is of much importance in determining the viability of cells after freezing them at below normal temperatures. Tetraselmis gracilis showed survival on exposure to 5 to 30% (v/v) DMSO, 5 to 25% methanol and 5 to 40% glycerol for periods of up to 2 h. DMSO and methanol were lethal at higher concentrations (>10%)for Chlorella marina and Chaetoceros calcitrans even on exposure for 15 min. At 25%, DMSO was so much lethal that the cells of C. calcitrans and C. marina were dead even after 60 sec. At 20%, all cells were dead within 60 min. Safer concentrations for DMSO were at 5% and lower. Methanol incubations significantly reduced cell viability above 25% (60 sec) for T. gracilis, 15% (up to 20 min) for C. calcitrans and 20% (up to 60 min) for C. marina. All the three algae could tolerate glycerol even up to 30% (60 min). The survival was highest at 10% concentration of glycerol for 120 min. Based on cell recovery rate after 24 h post thaw and growth rate determination, DMSO at 5% or 10% glycerol are the best treatments for cryopreservation. Glycerol was found to be better than DMSO in all the three cases. Post thaw viability in 5% methanol was almost negligent for all the three strains. Page(s): 243-247

Developmental and reproductive strategies of two marine algae Gracilaria corticata (Gigartinales, Rhodophyta) and Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) from Port Okha (Gujarat), west coast of India

Fri, 01 Sep 2000 00:00:00 GMT

Title: Developmental and reproductive strategies of two marine algae Gracilaria corticata (Gigartinales, Rhodophyta) and Asparagopsis taxiformis (Bonnemaisoniales, Rhodophyta) from Port Okha (Gujarat), west coast of India Authors: Kumar, Manoj; Jha, Aditya; Vijayaraghavan, M R Abstract: The coastal ecosystem of Port Okha (Gujarat) has distinct supratidal, intertidal and subtidal zones which demand specific or particular developmental and/or reproductive adaptations of existing algae. Gracilaria corticata grows in intertidal regions whereas Asparagopsis taxiformis occurs in subtidal regions. In G. corticata wavy outline, compact arrangement of cortex and medulla, wall ingrowths in the medullary cells at thallus-holdfast transition zone and sulphated polysaccharides in the intercellular mucilage provides strength and flexibility to the thallus and protect the seaweeds against physical damage and constant environmental stress conditions. In contrast, the rhizomatous region of A. taxiformis does not anatomically differ from the thallus and is not modified because the plant grows in the tidal fringe which is not subjected to strong wave action. The well developed rhizomatous region helps the plants in propagation. Gracilaria corticata is a dioecious plant with three distinct season specific ph ases of diplobiontic life-cycle. However, A. taxiformis completes its life-cycle in two phases i.e. gametophyte and carposporophyte. The carposporophyte phase of two red algae is concerned with amplification of the diploid stage, because fertilization chances are meagre due to non-motile sperms. The carpospores are gorged with floridean starch grains, fibrous vesicles and chloroplasts. Page(s): 248-252