INDIAN J. MAR. seL, VOL. 5, JUNE 1976

out the period of investigation. The samplescollect~ from the fore5hore zone between' 2000and 5600 m on the northern side and between 500

and 2600 m on the southern side (Fig. 1) showedthe presence of tracer grains in almost all thesamplel The presence of tracer grains in thesample~ from foreshore zone indicates ,horewardmovement of offshore sediments. Shoreward andseaward dispersion of tracers seem to be due tosorting effect caused by waves and tides.

In case of beach, maximum concentration oftracers lis observed WSW and NW of the releasepoints. The waves were breaking close to 5horeavoiding formation of surf during high tide. There­fore, the above concentration of tracers seem tobe due to zigzag movement or sediments causedby wa~es approaching the coast from south-east.It may' be inferred fWIn the concentration patternthat be~ch sand moves west-south-we: tward duringhigh tide in February when waves approach thecoast from south or south-east. The dredgedmateria~ should be disposed off quite far of fromthe chaiImel on the northern side during Februaryto avoi~ siltation of the same.

The author is thankful to Paradip Port TrustAuthorities for providing launch, location of thesample3&data on waves, and other facililies. Thanksare also due to Shri V. R. Venkoba Rao, Director,and Shqi P. R. Chandra, Geologist (Sr), for criticallygoing through the manuscript.References

1. Indiai Meteorological Department, Winds, weathers andcu ents on the coasts of India and the laws of storms,19 2, 77-

2. Naval Hydrographic Office, The Indian tide-tables, 1972.3. SIDDIQUlE, H. N. & SHRIVASTAVA, P. C., Curr. Sci., 39

(1970), 451.4. SHRIVASTAVA, P. C., Indian J. mar. Sci., 4 (1975), 95.5. SHRIVIASTAVA, P. C., Marine Geol., 9 (1970), M43.6. SHRIv!AsTAVA, P. C .• J. geol. Soc. India, 16 (1975). 79.

7. INGLE!(Jr), J. C.• The movement of beach sand (ElsevierPublishing Co., Amsterdam), 1966, 221.

Distribution of Suspended Matter in Watersof the North-Western Shelf of India

CH. M. RAO & G. V. RAJAMANICKAM

National Institute of Oceanography, Dona Paula 403004

Received 10 October 1975; revised received 25 March 1976

Sixty-five water samples from surface and bottomwere collected for the study of suspended matter innorth-western Arabian Sea from December 1973 toMay 1974. Concentration of suspended matter insurface ~ater varied f~om 0·3 to 4·6 mgjlitre while atthe bottom it varied from 0·5 to 13·6 mgjlitre. Highconcentration of suspendledmatter in its coastal waterand in the vicinity of river mouth was due to inertmateriaL In regions away from the coast higher con­centrations of suspended matter were presumablydue to a greater plankton production.

STUDY of particulate suspended matter 111 sea­watetr is important in understanding (i) genesis

of sediments in oceans, (ii) transport and dispersal

124

of suspended material inI0 a ba~in, (iii) relativecontribution of terrigenous, volcancgenous, bio­genous and chemogenous material to suspendedmatter and variation in its concentration at differ­ent depths. Study of particulate maHer is al,:oimportcmt for forecasting t hE fisheries of a particularregicn as the particulate matter forms focd for alarge variety of marine life. Lisitsyn1, Gordeev2:and Serova3 haVEstudied the distribution and com­position of suspended matter in the Indian Ocean,but their studies did not cover the continentalmargin. The present study, though of a prelimi­nary nature, is the fir~t attempt in this direction ..

SamplEs of water were collected from Decemberto May 1974 during the INS Darshak Oceanogra­phic Expedition ,1973-74) in the nOIthern ArabianSea. Samples were collected from the surface andabout 5 m 8.bove the bottom bv a van Dornsampler of 7 1 capacity. Sampling was lc.rgelyrestricted to the shelf area, although some surfacesamples were collected beyond the shelf aLo. Each_sample was filtered on board using pre-weighedmembrane filters (47 mm diam. with 0·45 pores).Samples were stored in de:;iccators and subcequentlyweighed to the nearest 0·01 mg for estimating theconcentration of suspended matter.

Concentrations of suspended matter in the surface­water ranged from 0·3 to 4,6 mg/litre. Higherconcentrations (>4 mg/litre) were found in theGulf of Cambay and in a narrow strip bordering thecoast, as far as Ratnagiri area (Fig. 10.). Moderateconcentration (2 mg/litre) was found spreading toa distance of about 20 km. This represented anunusual situation as no other tropical oceanic areastudied by earlier workers showed such a dispersal.North of the Gulf of Cambay, off the KathiawarCoast, particularly off Porbander, the concentrationwas considerably reduced. The concentration ofsuspended matter again increased (>1 mg/litre) inthe vicinity of the mouth of the river Indus.

The concentration of suspended matter in thebottom waters ranged from 0·5 to 13·6 mg/litre.It was particularly high in the Gulf of Cambayand in a narrow belt extending from Daman toRatnagiri (Fig. 1b). The suspended matter bothin bottom and surface waters generally decreasedfrom the shore towards the open ocean. However,a slight increase in the concentration at the surfacewas often noted in the outer shelf region.

Examination of concentrations of suspended matterbroadly divides the area into 3 regions: (i) regionof the Gulf of Cambay and a narrow belt along thecoast down to Ratnagiri, (ii) a belt along the Kutchand Kathiawar coast, and (iii) the region south ofthe mouth of the river Indus. Though the concen­tration of suspended matter was high in both surfaceand bottom waters, higher concentration in bottomwaters persisted over a greater distance. Alongthe outer shelf, surface concentrations were rela­tively higher than those of the bottom. High sus­pended matter was generally restricted to the innershelf particularly in areas with fine-grained bottomsediments. Folger et at.' noticed a similar distri­bution in the waters of Somes Sound of Maine.

Main sources of suspended matter in the oceanare river run-off, biological productivity and eolian

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H. SURYANARAYANAN & N. BALAKRISHNAN NAIR

Received 8 } anuary 1976; revised received 25 February 1976

Depa.rtment of Aquatic Biology & FisheriesUniversity of Kera.la., The Aquarium, Trivandrum 695007

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Seasonal Variations in BiochemicalConstituents of Cellana radiata (Born)

1. LISITSYN, A. P., in Sovremennyye osqdkimorev i okeanov(Recent marine and oceanic sediments), Moscow, 1 Zd,AN USSR, 1961.

2. GORDEEV, E. 1., Okeanolog. issled., 18 (1968), 156.3. SEROVA,'·V:'V., Olleanolog. issred., 3 (1969), 378.4. FOLGER, D. W., MEADS, E. H., JONES, B. F. & CORY,

R. L., Lymn. Oceanogr.,:3 (1972), 394.5. PUSTEL'NIKOV, O. S., Oceanology, 6 (1969), 816.6. EMELYANOV, E. M. & SHIMKUS, K. M., Suspended matter

in the. Mediterranean Sea (A natural sedimentationlaboratory, edited by D. J. Stanley), 1973, 417.

7. EMERY, K. 0., MILLIMAN, J. D. & ELAZAR UCHUIPI,]. Sed. Petrol., 43 (1973), 822.

8. MANHEIM, F. T. & ,MEADE, R H., Science, 167 (1970),371-376. -,

9. MANHEIM, F. T. & HATHAWAY, J. C., Lymn. Oceanogr., 1(1972), 17.

.' Moisture, glycogen, protein, total lipids and ashcontent in the tropical intertidal limpet C. radiata wereestimated ....Two distinct periods of vari.atjons werenoticeable; the 1st extending from March to' Octoberindicating high breeding activity when water contentand protein values were high and the 2nd indicatingth!:lperiod of rest from October to March when glycogencontent-was .high•.

-126

dust. The colour of the suspended matter retained - .High surface values found offdiore (off Ratnagiri,on the filter showed three distinct zones of demarca- off Daman an<:J.northernmost part of the studytion. In. the Gulf of Cambay and the adjoining belt, area) may be attributed to higher plankton produc­from Daman to Ratnagiri and south of the Indus tivity prevailing in the off~hore region. Similarmouth, where more terrigenous material is avail- cases of high plankton produciic.n have been noticedable, the colour included the various shades of brown - in the Baltic Sea.5, the. Atlantic Continental Margin(5YR and lOYR). On the Kathiawar shelf, an and -the. Gulf d IVIexico9•area of comparatively lesser terrigenous supply, The authors are grateful to Capt. K. L. Chopra,the colcur of the material on the filter was light Commander, INS Darshak, and his officers for pro­greenish ,grey to yellowish grey (5Y). Along the viding shipboard facilities, to Dr S. Z. Qasim andouter shelf, where the bottom is covered by chemo- Shri H. N. Siddiquie for going through the manu­genous and biogenous sediments, colour of the sus~ script critically and to Dr V. Narayanan and Shripended lpatter on the filter wa'3 from light grey F. Almeida for collecting the samples.(N8) to yellowish grey (5Y). It is noteworthy R f

- d .. e erencesthat the colour of the suspen ed matter retamedon the filter of the bottom samples especially on theouter shelf was almost similar to that of the sedi­ment. This indicates that the suspended matternear the, bottom wasstirri'd 'up -sediment: In the'Gulf of Cambay and from Daman to Ratnagiri,the suspended material from the bottom samplesalso included the resuspended material.

Study of regional variations of the suspendedmatter indicates the occurrence of high concentra­tions near the river mouths. High concentrationsjn the G~lf of Cambay are due to the discharge ofsediment! by the rivers Mahi, Sabarmati, Narmadaand Tapti. Similar distribution of concentrationsof susperded matter and its relationship to riversource3 are reported from the Baltic Sea5, the Medi-terranean Sea6, the continental margin from CapeCod to'the Florida Keys7, and from' the south­eastern Atlantic Oceans.

High concentrations along the coast, extendingfrom Daman to Ratnagiri, may be due to the supplyof suspended material by small rivers and also insome areas due to intense coastal abrasion and{;hurning up of sedimentary material. The presenceof rock ;outcrops at 20000'2'N,' '72°35-3'E, substan­tiates a greater activity of <::urrents.in this area.This strip of high suspended matter doe? jlots-p~eadwider which may probably be due to -the presence'{)f strong long shore currents which do !lot permitjts dispersal very far off.the.-s.hQfs\...J-ower concen­tratioll' !of suspended matteL_off the Kathiawar'and Kutch coasts may be due totne~-ar..j.d,conditiongenerally prevailing on land and .];>ecauseof theabsence of rivers in thiSarea~'"'- ,,< ..=~ ..,...•..••..,,-~<h ..••••••••• __ -.>-:a- __ -,.......,.-. ~ .•• - .••••••.-"-",-:-~-._ ••.• -- .•••.. :"'"P-'-- • _-~ -

In the Gulf of Cambay, Ui:e-CConcentratlOrl-ofsuspended matter decreases from the cdast both in . _ .the sudace and bottom waters. Howe':.~f, in the INTERTIDA~ molluscs .constitute. an interestingbottom Iwaters , higher concentrations persist to a !?roup by v~rtue of theIr natural abundance andgreater distance offshore, as was found in the Baltic then. ~daptabIlit~ to the changing environmentalSea5• ~his may be due either to the resuspension condltlO!ls. ConSIderable attent,ion' has. been focus­{)f bott6m' sediments by the activity of ,bottom e~ on dl~'ferent aspects of intertidal molluscs espe­(;urrentsl or settling of bulk of sediments .quickly clally WIth _refetence to their distribution andto the bottom and dispersal offshore by the bottom zonation, heat resistance, feeding rates,' ecology,currents. Comparative studX of the 2 mg/litre adaptability, biochemical composition and reproduc­.contour for both surface and'bottom indicates that tion1. During our studies on· the reproductiveat the, bottom the concentration increases towards cycles of the intertidal molluscs of Kovalam beachsouth-west. This probably indicates the main on the south-west coast of India, seasonal biochemi­direction of dispersal and the cij:rrents elevation in cal .changes in th~ tropical intertidal limpet Cellanathis area. The intermediate values in the northern rad~ata have been studied with special referenceportion may be attributed to' the influence of the to sex. "river Indus which brings a considerable amount of Forty to fifty sp~cimens of C. radiata were collect­sediment wmeh---'gets~s~¥se4~...,a...la.-r-ge.o-ar~a._.,..,,,",,,,-~~A,.fAj;J.mght.J¥=~-¥als-_.ducing~ ..l9'13-74, from