FT Vol.37(2)

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    Suspended Matter Distribution in Beypore Estuary
    (Society of Fisheries Technologists (India)Cochin, 2000) Nair, M.N. Muraleedharan; Lakshmanan, PT.
    Suspended matter concentration (SMC) in the Beypore Estuary during pre-monsoon and monsoon periods from ten stations during 1987-1988 are presented. Variations in suspended matter load at different water levels over the tidal cycles were monitored at one station. Relatively higher values were obtained during monsoon months compared to premonsoon period. The highest value of 143 mg.l"1 was observed during September 1987 while the lowest value of 2 mg.l"1 was obtained during January 1988. Inverse relationship between suspended matter concentrations and salinity was observed during monsoon months. However, the relationship did not hold good during post-monsoon and summer months. Observations during tidal cycles have shown that bottom waters always registered higher values in suspended matter load, most probably due to the re-suspension of bottom mud owing to scouring effect of tidal currents. Sediment content was found to co-vary with the increase in salinity during summer months. Material brought in through river run off contributes mainly to the suspended matter load in monsoon period while particles of marine origin have the major share during summer season
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    Seasonal Variations in Hydrographical Parameters, Nutrient Content and Energy Content of the Suspended Particulate Matter in Netravathi - Gurpur Estuary
    (Society of Fisheries Technologists (India)Cochin, 2000) Vedamurthy, A.P; Ramesha, TJ; Lakshmipathi, M.T; Hariharan, V
    An attempt has been made to study the energy content distribution in the suspended particulate matter of Netravathi-Gurpur estuary. Hydrological parameters and nutrient content exhibited seasonal variations. Suspended particulate matter gradually increased from January onwards till May at all the stations. The higher particulate matter concentration of 218 mg. I"1 was reported in the month of December. The energy content of detrital matter was less during June to September in spite of greater concentration.
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    Seasonal Variation of the Environmental Parameters along Fort Cochin Beach
    (Society of Fisheries Technologists (India)Cochin, 2000) Jayalakshmy, K.V; Raveendran, O; Sreeja, S
    Monthly observations on heterotrophic bacteria, organic carbon, temperature, salinity, dissolved oxygen, inorganic phosphate, nitrate, nitrite and ammonia from surface water and from water table level during high tide, mid tide and low tide were carried out in the Fort Cochin beach for a period of one year. Also, monthly observations on heterotrophic bacteria, organic carbon and temperature were carried out for the same period from sand during the three tidal levels at surface and water table level. The study showed that organic carbon in sand controlled the bacterial population to a great extent during high tide at surface and during low tide at water table level. Step-up multiple regression analysis showed that in water the interaction effect of inorganic phosphate and ammonia and that of ammonia and temperature were the most important parameters controlling the bacterial production whereas in the sand at the surface, temperature-organic carbon interaction effect was the controlling parameter. The results of the Q-mode analysis are also presented.
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    Optimization of Mesh Size of Gill Nets to Capture Amblygastar sirm,(Walbaum) in Thoothukkudi Coastal Waters, Southeast Coast of India
    (Society of Fisheries Technologists (India)Cochin, 2000) Neethiselvan, N; Jude, D; Sundaramoorthy, B; Gopalakrishnan, P
    Amblygastar sirm, a lesser sardine, popularly called 'Keeri Meen Chalai' form a notable fishery in Thoothukkudi coastal waters with peak season from September to February. A. sirm are captured in small meshed drift gill nets with the mesh size ranging from 26 mm to 32 mm. The fishery is mainly constituted by the size group 65-210 mm. The present study deals with the optimization of mesh size to capture the commercially significant length group (141-190 mm) and enmeshing pattern of A. sirm in gill nets with various mesh sizes. The optimum mesh size for the commercial exploitation of A. sirm in Thoothukkudi coastal waters is found to be 30.5 mm
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    Individual and Combined Acute Lethal Toxicity of Monocrotophos and 2,4-D on the Juveniles of Etroplus suratensis (Bloch) (Pisces: Cichlidae)
    (Society of Fisheries Technologists (India)Cochin, 2000) Nair, J.R. Rajasekharan; Mercy, T.V. Anna; George, Renu Maria
    The 48 h individual and combined lethal toxicity of monocrotophos (insecticide) and 2,4-D (herbicide) on the juveniles of Etroplus suratensis were determined. The 48 h LC of monocrotophos was 5.85 mg.l4 (5.02 to 6.69) and that of 2,4-D was 267.4 mg.l"1 (228.93 to 305.86). The median additive index and its range for the combined toxicity were worked out. The calculated value was -0.185 (-0.541 to 0.083). A simple or strictly additive toxicity is indicated for the mixture of monocrotophos and 2,4-D. This shows an enhanced potential of the individual toxicant for pollution in the natural bodies when they are applied sequentially and even simultaneously