Indian Journal of Marine SciencesVol. 2, June 1973, pp, 54-61

Quantitative Distribution of Planktonic Foraminifera In theSouth- West Coast of India

K. KAMESW ARA RAONational Institute of Oceanography, Panaji, Goa

Received 12 January 1973; revised received 20 March 1973

Twenty-six species of planktonic Foraminifera have been identified from plankton and sedl-ment samples, collected durfng the Blue-Fin cruise-4 in March 1971,from the south-easternArabian Sea. Shelf waters are dominated by species belongtng to the ~enera Globigeri noides ,Globoquadrina and Globigerinita while the bathyal regtons are represented by species of thegenera Globorotalia and Sphaeroidinella. Some species such as Globigeri noides congtobatus ,G. sacculifer, Globorotalia menard;;, G. tumida, Pulleniatina obliquiloculata and Sphaeroidi-nella dehiscens which are characterfsttc of Iow-latitude regions of the wcrld oceans are encoun-tered in the south-west coast of India. As compared with the Bay of Bengal, in the Arabian Seafauna there is a great diversity of species which can be attributed to increased salinity of theArabian Sea waters. The quantitative distribution of this group shows that very high concen-trations of these Foraminifera are present in the offshore regions of Afleppey and Qutlon.

INview of the importance of planktonic Foramini-fera as sediment producers and indicators ofoceanographic conditions of the sea besides

being useful in dating sediments, increased interesthas been laid on studies related to taxonomy,ecology and distribution of this group in the worldoceans. In comparison with the Indian Ocean,the Pacific and Atlantic Oceans have been studiedin greater detail with respect to planktonic For-aminifera. Although earlier expeditions, Challenger(1872-76) and John Murray (1939), have made signi-ficant contributions on the presence and distributionof planktonic Foraminifera, information on ecologyand geochronology of this group in the IndianOcean could be obtained only after the beginningof International Indian Ocean Expedition (1962-65).

Research cruises of INS Darshak conducted bv theInstitute during 1966-69 have given a considerableaccount of planktonic Foraminifera present in thenorth-west coast of India':". No detailed study hasbeen made on quantitative distribution of thespecies apart from reports=" on some common formsin the south-eastern Arabian Sea. The present studyhas been taken up to determine the species com-position of planktonic Foraminifera and distributionin the investigated area, based on plankton andsediment samples collected on board Blue-Fin, afishing trawler belonging to Central Institute ofFisheries Operatives, Cochin. Fifteen planktonsamples have been collected towards the sea per-pendicular to the coast off Cochin, Alleppey andQuilon and also 3 sediment s.ampJes h~ve beenobtained from the coast off Cochin, Locations fromwhich these samples were collected are given inFig. l.

Materials and MethodsPlankton and sediment samples were examine a

for the specimens of planktonic Foraminifera.Vertical hauls of plankton were made at all thestations 1 to 15 using the Heron-Tranter net (moutharea, 0·25 m2; net length, 2·50 m; aperture size,

54

0·2 mm). For the determination of the amount ofwater passed through meshes of the net, a Rigoshaflow meter was used at the centre of the net.Three sediment samples at stations 3 to 5 werecollected with a Lafond-Dietz snapper.

Oceanographic Conditions

Two distinct water masses have been identifiedalong the south-west coast of India: (i) Arabian SeaWater and (ii) Equatorial Surface Water. Thesalinity of Arabian Sea Water has a value ranging

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KAMESWARA RAO: FORAMINIFERA IN THE SOUTH-WEST COAST OF INDIA

horn 35 to 35·5%0 during postrnonsoon season andit decreases with depth. Sinking of this watermass takes place during winter and is replaced byEquatorial Surface Water which moves northwardsalong the coast. In this water salinity increasesfrom the surface downwards. It has been foundthat a salinity maxima layer of water exists betweenthe two water masses. During premonsoon months,relatively stable hydrographic conditions exist in thewaters of south-eastern Arabian Sea. Collections ofsamples have been made in March 1971 from theabove region during the Blue-Fin cruise-s andhydrographic observations during this cruise areconfined to the measurements of salinity and tem-perature of surface water. In the coast off Cochinsalinity varies from 33·2 to 33·45%0 and tem-perature from 29° to 29·7°C; in the Alleppey coast,salinity varies from 33·45 to 33·65%0 and tem-perature from 28·5° to 29'I°C; and in the Quiloncruise track, salinity varies from 33·7 to 34·05%0and temperature from 28.7° to 29·9°C.

Systematics

Twenty-six species of planktonic Foraminiferahave been identified from the plankton and sedimentsamples collected and the classification adoptedagrees with that of Parkers.

Order FORAMINIFERIDA

Family GLOBIGERINIDAE Carpenter,Parker & Jones, 1862

Genus Globigertna d'Orbigny, 1826

Globigerina bulloides d'Orbigny

Globigerina bulloides, d'Orbigny"; Parkers; Be' andHamlin-": Bhattll

This species is characterized by a strongly archedumbilical aperture with no lip.

It has been (bserved in the plankton samplesfrom the sites where depth of water is more than50 m and also in the sediment samples from sites3,4 and 5. The greatest abundance 1710 specimens!1000 m3 of water is found at station 6 off AUeppey.

Globigerina calida Parker

Globigerina calida, Parkers; Bhatt-!

Specimens of this species have a trochospiral testwith radially elongated final chamber with anumbilical extraumbilical aperture having a distinctlip. It is found in the plankton samples at stations4 and 6 and in the sediment samples collectedoff Cochin.

Globigerina jalconensis Blow

Globigerina jalconensis, Blow-": Parker"

This species resembles Globigerina bulloides, butit can be readily distinguished from the latterby its low arched umbilical aperture with a lip.It is not encountered in the plankton samples.In the sediment samples at stations 3 and 5off Cochin it formed slightly more than 5% of thetotal fauna.

Globigerina pachyderma (Ehrenberg)

Aristerospira pachyderma, Ehrenberg's: Globigerinapachyderma, Parker": Be' and Hamlin-": Bhatt-'

Specimens typical of tropical warm waters havingshells coiled towards right side have been foundin the sediment sample at station 5 forming only1% of the total fauna. This species has not beenobserved in the plankton samples.

Globigerina quinqueloba Natland

Globigerina quinqueloba, N atlandt+: Parkers; Be' andHamlin-v ; Bhatt.'! .

This form can be distinguished by its 5-6 chambersin the final whorl with a final chamber extendingover the umbilicus.

It has been found in the sediment samples fromsites 2 and 3 off Cochin.

Globigerina rubescens Hofker

Globigerina rubescens, Hofker>: Parkers; Be' andHamlinlo

This small species which is characteristic oftropical waters has been observed in the planktonsamples at stations 7, 14 and 15. It formed lessthan 5% of the total fauna in the sedimentscollected from stations 4 and 5 off Cochin,

Genus Globigertnelta Cushman, 1927

Globigerinella aeqeilateralis (Brady)

Globigerinella siphonijera (d'Orbigny), Parker";Bhattw: Globigerinella aeqailateralis, Be' and Ham-lin-?

It has a test with planispirally arranged chambersin the adult with an equatorial aperture which isinteriomarginal.

This species has been observed in planktonsamples from the offshore regions 4, 6 and 15 offCochin, Alleppey and Quilon respectively. Also,in the sediment samples collected from the offshoreregion of Cochin.

Globigerinella adamsi (Banner and Blow)

H astigerina (Bolliella) adamsi, Banner and Blow'":GlobigerineUa adamsi, Parker" '

Test planispiral with radially elongated finalchambers as in Globigerina calida and G. digitata.It has an umbilical equatorial aperture which isinteriomarginal.

This is a rare species found at stations 6 and 7(in plankton samples) and 5 (in the sediment).

Genus Hastigerina Thomson, 1876

Hastigerina pelagica (d'Orbigny)

H asiigerina pelagica, Brady!": Parkers; Be' andHamlin10

Test planispiral with triradiate spines, apertureequatorial. This species is common in tropicalwaters.

55

INDIAN J. MAR. SCI., VOL. 2, JUKE 1973

In the samples collected it has been observed intwo plankton lOWS (stations 7 and 15) and in thesediment (station 5). In both sample types itconstitutes less than 5% of the total fauna.

Genus Globigerinoides Cushman, 1927

Globigerinoides conglcbaius (Brady)

Globigerina conglobata, Brady!": Globigerinoidcs coll-globatus, Parke I 8

Test trochcspiral with four chambers in the finalwhorl with an umbilical aperture on the ventralside and two secondary apei tures for each chamberon the dorsal side.

It is observed. in plankton tows from the sites6, 7 and 14 and in all sediment samples collectedfrom the coast off Cochin. In both types of samples,it forms less than 5% of the total fauna.

Globigerinoides ruber (d'Orbigny)

Globigerina rubra, d'Orbigny!"; Globigerinoides ruber,Parker": Be' and Hamlin1o; Bhattll

This species is common in the south-west coastof India and observed at most of the stationsstudied.

Globigerinoides sacculifer (Brady)

Globigerina sacculifera, Bradyw: Globigerinoides quad-rilobatus sacculifer, Parker": Globigerinoides sacculi-[er, Be' and Hamlin-?This species can be identified easily by its sac-like

final chamber with a secondary aperture for eachchamber on the dorsal side.

It is found in most plankton samples collectedfrom the areas where the depth of water is lessthan 200 m and forms more than 5% of the totalfauna whereas in the sediments collected from thecoast off Cochin it never exceeded 5% of the fauna.

Genus Orbulina d'Orbigny, 1839

Orbulina «nioersa d'Orbigny

Orbulina «niuersa, d'Orbigny!": Parker": Be' andHamlin-"

Adult specimens with a spherical test have beenobserved. This species is widely distributed inAtlantic, Pacific and Indian Oceans.

It is observed in plankton tows at stations 5, 6,14 and 15 and forms more than 10% of the totalfauna in the offshore areas of Alleppey and Quilonand less than 10% in the sediments collected fromthe coast off Cochin.

Genus Pulleniatina Cushman, 1927

Pulleniatina obliq1.iloc~llata (Parker & Jones)

Pulleniatina obliquiloculota, Carpenter, Parker &Jones2l; Be' and Hamlint"

Test with 3t chambers in the final whorl of thetest, aperture extraumbilical and wall smooth.

It is found in plankton samples at stations 7 and14 forming more than 5% of the total faunaand is common in the offshore region of Cochin.

56

Genus Sphaeroidinella Cushman, 1927

Sphaeroidinella dehiscens (Parker & Jones)

Sphaeroidina bulloides d'Orbigny var. dehiscens, Par-ker & J ones22; Sphaeroidinella dehiscens, Parkers

It is a typical low-latitude species observed in theplankton samples at stations 5, 14 and 15 offCochin and Quilon and also in the sediment samplefrom station 5.

Genus Globorotalia Cushman, 1927

Globorotalia crassafcrmis (Galloway & Wissler)

Puloinulina crassa (d'Orbigny), Brady!": Globorotalia.crassaformis, Parker": Be' and Hamlinlo

This is a rare species observed in the sedimentsample at station 5 off Cochin.

Globorotalia inflata (d'Orbigny)

Globigerina inftata, d'Orbignyt": Globorotalia inftata,.Parker"; Be' and Hamlin-"

Test with 4-5 chambers in the final whorl having.coiled to the left side are encountered; wall non-spinose.

It has been observed in a single plankton sample-at station 6 off Alleppey.

Globorotalia hirssua d'Orbigny

Rotalina hirsuta, d'Orbigny23;. Globorotalia hirsltta •.Parker"; Be' and Hamlinw

Test trochospiral compressed and surface coveredwith very fine spine like structures. Apertureextending from tne umbilicus to the peripherywith a distinct lip.

It has been observed in the plankton sample(station 6) off Alleppey and in the sediment samples(stations 4 and 5) off Cochin forming less than2% of the total fauna.

Globorotalia trwncatulinoides d'Orbigny

Rotalia truncatulinoides, d'Orbigny=': Globorotalia.truncaiulinoides, Parker 8 ; Be' and Hamlin10

This species is rare in the area studied. In theplankton sample (station 6) and sediment samples(stations 4 and 5), it forms 1% of the total fauna ..

Globorotalia menardii (d'Orbigny)

Rotalia (Rotalie) menardii, d'Orbigny": Globorotaliacultrata, Parker": Globorotalia menardii, Be' andHamlinlO; Bhattll

This species is common in the south-west coastof India and forms less than 10% of the totalfauna in the plankton samples at stations 5-7,.14 and 15. It is also found in the sedimentsamples collected from the coast off Cochin formingmore than 5 % of the fauna.

Globorotalia menardii flexuosa (Koch)

Globorotalia menardii flexuosa, Be' and Mclrit yre!

Be' and Mclrrtyre! discovered for the first timethis species in living condition from the Indian

KAMESWARA RAO: FORAMINIFERA IN THE SOUTH-WEST COAST OF INDIA

Ocean but not recorded so far from the recentdeposits of Atlantic and Pacific Oceans.

In the present study it has been taken fromplankton and sediment samples collected fromstation 5 off Cochin.

Globorotalia tumida (Brady)

Puloinulina menardii (d'Orbigny) oar, tumida,BI ady-": Globorotalia tumida, Parker"

Test with 5-6 chambers in the final whorl and is'elongated towards the final chamber.

This species is observed at 7 stations (3 to 7,14 and 15) in the plankton samples. Like G.menardii, this species also forms 5% of the totalpopulation of planktonic Foraminifera in the sedi-ment samples collected.

Genus Globoquadrina Finlay, 1947

-Globoqwadrina conglomeraia Schwager

Globigerina conglomerata, Schwagers+: Banner andBlow25; Globoquadrina conglomerate, Parker"

Adult specimens have four chambers in the finalwhorl, surface pitted and aperture umbilical. It isknown so far only from the Indo-Pacific regionand has been observed in the sediment samplescollected from the coast off Cochin.

Globoquadrina dutertrei (d'Orbigny)

Globigerina dutertrei, d'Orbigny-": Globoquadrinadutertrei, Parker": Be' and Hamlin-": Bhatt"!

It can be readily distinguished by the presence ofumbilical teeth, test wall pitted and nonspinose.It is common in the nearshore waters ofsouth-eastern Arabian Sea and forms morethan 5% of the fauna in the sediment sample atstation 4.

Globoquadrina hexagon a (Natland)

Globigerina hexagona, N atlandw; Globoquadrina hexa-gona, Parker"Test compressed with 5 to 6 chambers in the

final whorl of the adult, wall pitted and non-spinose. Aperture umbilical and in some casesit is extraumbilical with teeth. This species is res-tricted to Indo-Pacific region. In the presentinvestigation it is found in the sediment samplefrom station 3 constituting only 1% of the totalfauna.

Incertae Familiae

Genus Globigerinita Bronnimann, 1951

-Globigerinita glutinata (Egger)Globigerina glutinata, Egger-"; Globigerinita gl~ttinata,

Parker"; Be' and Hamlin-": Bhatt-!

Typical specimens with a bulla covering theumbilical region have been encountered. In theplankton samples at stations 5, 6, 8, 14 and 15and in the sediment sample at station 3, it formsmore than 10% of the total fauna.

Results and Discussion

The planktonic foraminiferal assemblage of thesouth-eastern Arabian Sea is a mixed one consistingof low-latitude, mid-latitude and high-latitude faunalelements. In general, the fauna is dominated byspecies characteristic of low-latitude waters of theworld oceans and they are represented by Globi-gerinoides conglobatus, G. sacculifer, Globorotaliamenardii; G. tumida, Pulleniatina obliquiloculata andSphaeroidinella dehiscens, Yet another species whichis found to be more abundant in the south-westcoast of India is Orbulin » universa. Kustanowich-?also has observed that it occurs in greater fre-quencies in the lower latitudes. Mid-latitude typesare composed of Globorotalia crassaformis, G. hirsuta,G. inflate, G. truncatulinoidee and Globigerina bul-loides while the high-latitude form Globigerinapachyderma also has been found in the fauna.Both mid-latitude (with the exception of Globi-gerina bulloides) and high-latitude forms are rarein the area studied. Their presence in the low-latitude waters of the Kerala coast can be attributedto the action of water currents. Cifelli-" ascribedthis overlapping of different faunal elements totemperature tolerance or adaptability of differentplanktonic foraminiferal species as seen in the caseof cold water species living over a wide range ofsea water temperatures. From the informationavailable on range of temperature tolerance ofplanktonic foraminiferal species, it is obvious thatthe grouping of species with reference to differentranges of temperatures of sea water29,30 seems to besatisfactory when compared with the classificationof species according to latitude as suggested byPhleger et ai», Three forms, Globoquadrina conglo-merata, G. hexagona and Globigerinella adamsi, whichare found only in Indo-Pacific legion have also beenencountered in the mea studied, A striking featureof low-latitude fauna especially in the Indo-Pacificregion is its greater diversity in species composition.

Distribution of planktonic species in this investi-gation shows that the shelf waters of the coast aredominated by the following forms: Globigerinoidesruber, G. sacculifer, Globoquadrina duiertrei andGlobigerinita glutinata while the waters cf thebathyal regions by species of Globorotalia andSphaeroidinella dehiscens, Thus based on the extent?f abundance of planktonic foraminiferal populationsIII waters and sediments, it is possible that they canserve as indicators in differentiating the shelf andbathyal zones of the marine environment (Table 1and Figs. 2-4).

Tcble 2 shows the presence of different planktonic .foraminiferal species in the regions studied' along theI~di~n c?asts. Species which show a wide range ofdls~nbuhon. along the Indian coasts are: (1) Globi-genn,a 1n:tll~~des, (2) Globigerinella aequilateralis, (3)Glo.blgennozdes ruber, (4) G. sacculifer, (5) Orbulinau:,zversa, (6) C!-loborota:Zzamenardii and (7) Globoquad-rina dutertrei, Species found in the Arabian Seabut not r~co~ded so far from the Bay of Bengal are:Globorotalia znjlata, G. p1tmilio, Globigerinita iota andG, uvula. The above tabulation of the species alsoshows .that in th~ Arabian Sea fauna there is a greatdiversity of species when. compared with that of the~ay of Beng~l.. This can be attributed to relativelyincreased salinity of the Arabian Sea waters. Onaverage, the salinity range of Bay of Bengal is

57

INDIAN J. MAR. SCI.. VOL. 2. JUNE 1973

30-33%0 whereas it is 34-37%0 for the ArabianSea39• Further species which seem to be charac-teristic of Bay of Bengal, are: Globigerina helicinae,G. parabulloidee and G. immaturus and these formshave not hitherto been reported from the ArabianSea.

Fertility of the sea with the help of planktonicForaminifera has been studied by some workers40•41

while Phlegerv has carried out this investigationwith benthic Foraminifera. Thus Foraminifera areuseful in locating productive areas in the sea. Highconcentrations of planktonic Foraminifera are usuallyfound in the regions of high organic production.In the present study, planktonic Foraminifera arefound to be abundant in the offshore areas of tnesouth-west coast of India. The greatest abundance(8040 specimensj l Ofx) m3 of water) is observed atstation 6 off Alleppey. This is followed by 7916

FIG.4

ST AnON NO.3

OFFSHORE REGiON

specimens/lOOO m3 of water at station 15 off Quilonand 5240 specimensrl Otn) m3 of water at station 5off Cocnin. Seaward from the shore to 40 m depthalong the south-west coast of India, the nearshorewaters are barren of planktonic Foraminifera.Relatively high concentrations of planktonic For-aminifera in the offshore regions of Alleppey andQuilon suggest high organic production in thesewaters since there is a direct zooplankton-phyto-plankton-nutrient relationship. Also, these highconcentrations agree in general with the tendencyof the zooplankton to increase in abundance towardsthe equator. Such high concentrations of planktonicForaminifera have also been noticed in the equatorialwaters of Pacific, Atlantic and Indian Oceans.On the basis of above observations Be' and Hamlin-?have concluded that the waters of equatorial regionsof the world oceans are very productive.

FIG.2

STATION NO.4

FIG. 3STATION NO.5

NEARSHORE REGION

Figs. 2 to 4 - Composition of planktonic Foraminifera in the sediments from the coast off Cochin

58

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KAMESWARA RAO: FORAMINIFERA IN THE SOUTH-WEST COAST OF INDIA

Acknowledgement

The author is indebted to Dr N. K. Panikkar,Director, for his interest and helpful suggestionsand to Dr T. S. S. Rao, Regional Centre of NationalInstitute of Oceanography, Cochin, for providing thenecessary research facilities. He is also thankfulto Shri M. C. Perumal, Director, Central Institute ofFisheries Operatives, Cochin, for making availablethe vessel Blue-Fin for the study and to the skipperand crew of the vessel for their cooperation in thecollections of samples.

References

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2. KAMESWARA RAo. K.. J. Bombay nat. Hist. Soc .• 68(1971). 9.

3. KAMESWARA RAO. K.. Proc. Indian Acad. 5ci .• 73 (1971),155.

4. KAMESWARA RAO, K.. Indian J. mar. su., 1 (1972), 1.5. SETHULEKSHMI AMMA, J., Bull. Res. Inst. Univ. Kerala,

6 (1958). 1.6. ANTONY. A., Bull. Dept mar. Bioi. Oceanogr .• 4 (1968), 11.7. SETTY, M. G. A. P., J. geol. Soc. India. 13 (1972), 131.8. PARKER, F. L., Micropaleontology. 8 (1962). 219.9. d'ORBIGNY, A. D., AnnIs su. nai., 7 (1826), 96.

10. BE', A. W. H. & HAMLIN, W. H., Micropaleontology, 13(1967). 87.

11. BHATT. D. K., Contr. Cushman Fdn Foramin, Res.,20 (1969), 30.

12. BLOW, W. H., Bull. Amer. Pal., 39 (1959), 67.13. EHRENBERG, C. G., K. Preuss Akad. Wi.ss. Berlin, (1861),

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