• R Jayaraman

      Articles written in Proceedings – Section B

    • Observations on the chemistry of the waters of the Bay of Bengal off Madras city during 1948–1949

      R Jayaraman

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      Studies were made on the distribution and seasonal variation of salinity, dissolved oxygen and nutrients in the surface waters of the Bay of Bengal in the vicinity of Madras during 1948–49. The various constituents show marked seasonal fluctuations. The variations of phosphates and nitrates during the period appear to be more regular than those of silicates. The influx of fresh water at a certain season during the year is offered as an explanation for this phenomenon.

    • Preliminary studies on certain changes in the Plankton and hydrological conditions associated with the swarming ofNoctiluca

      R Raghu Prasad R Jayaraman

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    • Observations on the composition of bottom muds in relation to the phosphate cycle in the inshore waters of the Malabar Coast

      G Seshappa R Jayaraman

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      Data have been collected on the temperature, pH, silt colloidal matter, moisture and phosphate content of mud samples from two selected stations of the West Hill Sea along the Malabar Coast.

      The variations in the several factors have revealed a distinct seasonal trend, the values being, in general, low for all the factors during the monsoon months.

      The bottom muds contain large quantities of interstitial and adsorbed phosphates in the non-monsoon period. During the monsoon there is a rapid release of phosphates into the overlying column of water.

      The factors associated with the monsoon release of phosphates from the muds are examined.

    • Salinity and temperature variations in the surface waters of the Arabian sea off the Bombay and saurashtra coasts

      R Jayaraman S S Gogate

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      The distribution of surface temperature and salinity in the waters of the Arabian Sea along the Bombay and Saurashtra coasts is presented and discussed.

      The two factors show seasonal trends associated with the prevalence of the two monsoons, South-West and North-East.

      In general, waters North of 20° N. latitude have a higher salinity and lower temperature than waters South of it.

      The variations in salinity and temperature indicate the possibility of seasonal upwelling in the coastal waters between 20° and 21° N. latitude and to a less extent upto 22° N. latitude during the period December to February.

      It is suggested that these mixing phenomena may be of great importance in determining the fertility of these waters.

    • Phosphorus cycle in the sea with particular reference to tropical inshore waters

      R Jayaraman G Seshappa

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      A brief account is given about the distribution and cycle of phosphates in the sea in the temperate and tropical waters, the recent investigations in the Indian waters being discussed in some detail. The data on the total phosphorus content of the waters along the Indian coast show that the values for total P are generally more than 3 times and sometimes nearly 40 times the values given by Harvey for the waters of Western English Channel. A hypothesis is presented which would explain the observed cycles of the phosphate-phytoplankton relationships on the Indian coastal waters to some extent, particularly in the Malabar waters. While the monsoon high values are caused by the release of locked-up phosphates in the bottom, it is suggested that a continuous source of replenishment is essentially to be presumed for the long duration of the simultaneous maxima of both phosphates and phytoplankton during the monsoon. Three such sources of replenishment are indicated. The post-monsoon ‘erratic’ fluctuations in phosphates and phytoplankton can be explained as due to a somewhat cyclical repetition of the usual phenomena of utilization, regeneration and phytoplankton production, until low levels of both phytoplankton and phosphates are established during the subsequent pre-monsoon months.

    • Biological and oceanographic differences between the arabian sea and the bay of bengal as observed from the Indian region

      N K Panikkar R Jayaraman

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      The paper presents some of the important differences in the oceanographical and biological conditions in the waters of the Arabian Sea and the Bay of Bengal along the Indian coasts. In discussing the biological variability of the two environments from the point of view of fishery productivity, attention is particularly drawn to the extremely complex nature of the oil sardine and mackerel fisheries, especially along the west coast of India, which accounts for the bulk of the fish landings. An attempt is being made to provide a suitable explanation for this on the basis of the nutrient distribution pattern associated with the occurrence of seasonal ‘upwelling’. It is also pointed out that the ‘upwelling’ processes along the west coast of India are also of a complex nature and the forces leading to this are yet to be properly understood. Some comparison is drawn between the conditions on the south-west coast of India and some of the classical upwelling regions of the world, particularly with reference to two important features, namely, formation and disappearance of temporary banks of mud and the occurrence of special planktonic blooms often leading to mass mortality of fish.

    • On the occurrence of oxygen maxima and minima in the upper 500 meters of the north-western Indian Ocean

      D Panakala Rao R Jayaraman

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      The depths of occurrence of oxygen maxima and minima have been studied in the upper 500 meters of the north-western Indian Ocean (including Arabian Sea and Laccadive Sea). The data collected by various ships during the International Indian Ocean Expedition were pooled into one degree grids and analysed for getting patterns of distribution—seasonally and regionally.

      The studies reveal that there is much variation in the depths of occurrence of oxygen maxima and minima in different areas and different seasons in the north-western Indian Ocean. Along the continental shelf all over the Arabian Sea, biological activity appears to play a predominant role in controlling the oxygen content, while in the open parts of the ocean the depths of occurrence of oxygen maxima and minima mainly appear to be governed by the water movements, circulation and mixing. one of the important observations is the existence of stagnant or near-stagnant conditions in the more central part of the Arabian Sea, restricting the exchange of water masses with the adjoining seas.

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