Indian Journal of Marine Sciences


Total visitors: 1,835  since 01-09-05

ISSN: 0379-5136

 

CODEN: IJMNBF

 

VOLUME  34

NUMBER  3

SEPTEMBER  2005

 

CONTENTS

 

Papers

 

 

δ 13C depleted oceans before the termination 2: More nutrient-rich

         deep-water  formation or light- carbon transfer?

 

249-258

 

        Virupaxa K. Banakar

 

 

 

 

 

Pteropod preservation profiles in seabed sediments off Middle Andaman Island in Andaman Sea

 

259-266

 

         D. Bhattacharjee

 

 

 

 

 

Evolution of Iskapalli lagoon in Penner delta region, east coast of IndiaΎ
A sedimentological and palynological approach

 

267-273

 

        J. Seetharamaiah, Anjum Farooqui, K.V. Suryabhagavan      K.Nageswara Rao

 

 

 

 

 

Pre-tsunami chemistry of sediments along the inner continental shelf off Ennore, Chennai, southeast coast of India

 

274-278

 

        N. Thangadurai, S. Srinivasalu, M.P. Jonathan, N. Rajeshwara Rao  &  R. Santhosh Kumar

 

 

 

 

 

 

Interpretation of gravity data over the 85° E ridge and Afanasy Nikitin seamount using spectral method

 

279-284

 

        A.R. Bansal & V.P. Dimri

 

 

 

 

 

Utility of natural generalised inverse technique in the interpretation

        of dyke structures

 

285-298

 

        M.M. Malleswara Rao, T. V. Ramana Murty, P.Rama Rao,     S.Lakshminarayana, A.S. Subrahmanyam & K.S. R. Murthy

 

 

 

 

 

Subareal wave pressures, layer thickness, run-up and run-down velocity

        on sea walls

 

299-309

 

        S. Neelamani

 

 

           [IPC Code: Int. Cl.7 E02B3/06]

 

 

 

 

 

Mangrove mapping and change detection around Mumbai (Bombay) using

        remotely sensed data

 

310-315

        V. Vijay, R.S. Biradar, A.B. Inamdar, G. Deshmukhe, S. Baji &

        Madhavi Pikle

 

 

 

 

Short Communication

 

 

Isolation of antagonistic marine bacteria from the surface of the gorgonian         corals at Tuticorin, south east coast of India

 

316-319

        K. Mary Elizabeth Gnanambal, C. Chellaram & Jamila Patterson

 

        [IPC Code: Int. Cl.7: A01N63/02]

 

 

 

Abstracts  of  the  Papers

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 249-258

 

d13C depleted oceans before the Termination 2: More nutrient-rich deep-water formation or light-carbon transfer?

Virupaxa K. Banakar

Geological Oceanography Division, National Institute of Oceanography, Dona Paula,

Goa-403 004, India

[E-mail: banakar@darya.nio.org]

Received 15 February 2005, revised 11 July 2005

Carbon-isotopes (d13C) composition of benthic foraminifera has been extensively used to understand the link between deep-water circulation and climate. Equatorial Indian Ocean d13C records of planktic- and benthic-foraminifera together show an unexplained shift in the long-term mean oceanic-d13C around the penultimate glacial termination (T2: 132 ka). The time-series planktic- and benthic- species d13C records exhibit two distinct mean-d13C levels. The low mean-d13C characterises the pre-T2 period (250 ka – 132 ka), while the post-T2 (~95 ka – Present) period records high mean-d13C, generating a one-time shift of ~0.4 ‰ within the last ~250 kyr time-period. This shift is a result of consistently higher-d13C in post-T2 glacial (and interglacial) periods as compared to the pre-T2 glacial (and interglacial) periods, and begins around the T2 (~132 ka), lasts until ~95 ka, and sustained through the T1. The normally observed glacial-interglacial d13C variations of ~0.3 ‰ occur as secondary fluctuations around the long-term primary mean-levels in the Indian Ocean, as well as in other oceans. The T2-d13C shift appears to be an inherent feature of the world oceans although with certain timing offsets. Therefore, it should represent a fundamental change in deep-ocean circulation (nutrient) dynamics. But, the leading hypotheses of circulation-driven oceanic distribution of d13C fail to explain the observed mean-d13C shift. Therefore it is proposed that, in addition to changes in deep-water circulation, the oceans before T2 were characterised by significantly lower-d13C than after. Such low-d13C mean-ocean during the pre-T2 period might have been the result of significantly increased transfer of terrestrial light-carbon to the ocean reservoir due to changes in global wind patterns.

[Key Words: Equatorial Indian Ocean, foraminifera-d13C, glacial termination-2, deep-water      circulation, role of   atmosphere]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 259-266

 

Pteropod preservation profiles in seabed sediments off Middle Andaman Island in Andaman Sea

D.Bhattacharjee

OPEC-I, Marine Wing, Geological Survey of India, 9&10 Raja S.C. Mallik Road, Kolkata-700032, India

(E-mail: debajyoti 1955@ yahoo.com India)

Received 6 July 2004; revised 26 April 2005

Quantitative studies of the major microfauna from 19 gravity cores and 8 grab samples and semi-quantitative studies of 47 surficial sediments, collected between 191m and 2334 m water depths off Middle Andaman Island and around Barren Island shows a characteristic relation of the microfauna with the physiographic domains in the Andaman basin. Craggy domain of volcanic arc zone in Andaman Sea reveals a variation of pteropod preservation profile (PPP) in the seabed sediments. The PPP bears a direct relationship with the nature of sediment, quantity of pyroclastic materials and physiographic configuration of the region. The degree of preservation of the dissolution prone pteropods and its numerical abundance at various water depths in 27 surficial sediments are utilized to examine the PPP in the area. These parameter can be applied to examine and compare different pteropod preservation domains in other parts of Andaman Sea for oceanographic inferences.

[Key words: Andaman Sea. aragonite compensation depth, dissolution indices, pteropod preservation profile, preservation index]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 267-273

 

Evolution of Iskapalli lagoon in Penner delta region, east coast of India—A sedimentological and palynological approach

 

J Seetharamaiah1*, Anjum Farooqui2, K V Suryabhagavan1 & K Nageswara Rao3

1Delta Studies Institute, Andhra University, Visakhapatnam – 530 017, AP, India

2Birbal Sahni Institute of Palaeobotany, Lucknow-226 020, UP, India

3Geo-Engineering Department, Andhra University, Visakhapatnam- 530 003, AP, India

 

*[E-mail: seetharamaiah_2004@rediffmail.com]

Received 16 November 2004; revised 24 May 2005

The Holocene evolution of the Iskapalli lagoon has been reconstructed through landform mapping, vibracore lithology and foraminiferal analysis, supplemented by radiocarbon dating. The characteristics: texture, boundary surfaces and the palynological assemblages of the lagoon sediments obtained from two cores indicate three distinct sediment units. The lower part of the core (Unit I) consisting of highly (>85%) oxidized coarse sand mixed with shells, moderate bioturbation, high concentration of Spiniferites, Casuarina, fungal spores and algal cysts together with terrestrial herbaceous taxa and sub-parallel laminations suggests deposition in a sandy river mouth bar environment under strong wave influence. The middle part of the core (Unit II) comprising high silty to sandy mud, and parallel laminations together with Protoperidinium sp., Rhizophora and Avicennia indicated low energy lagoonal environment analogous to the modern lagoonal conditions. The upper part of the cores (Unit III) consisting of well sorted fine sands with abundant terrestrial taxa are considered to be wind blown sands. The oxidized condition of the distributary mouth bar sediments of Unit I and the occurrence of fine sediments of Unit II suggest the lagoon had witnessed at least one cycle of sea level fall and rise during the Late Holocene between 2000 yr BP and 1500 yr BP.

[Key words: Vibracore sediments, palynology, Holocene sea levels, Penner delta, Iskapalli lagoon, east coast of India].

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 274 - 278

 

Pre-tsunami chemistry of sediments along the inner continental shelf off Ennore, Chennai, southeast coast of India

N.Thangadurai1, S.Srinivasalu1, M.P.Jonathan2, N.Rajeshwara Rao3 & R.Santhosh Kumar 2

1Department of Geology, Anna University, Chennai-600 025, India

   2Department of Geology, University of Madras, Chennai-600 025, India

        3Department of Applied Geology, University of Madras, Chennai-600 025, India

Received 8 November 2004, revised 24 May 2005

The inner continental shelf off Ennore hosts sediment carrying several minor metals of both natural and anthropogenic origin from the Korttalaiyar River through Ennore Creek. The sediments are mostly sandy silt and silty sand. The CaCO3 and organic matter contents in the sediment are very low (~ 2.1% and ~ 0.9%, respectively). The correlation matrix exhibits poor correlation between these components and minor metals indicating an insignificant role of CaCO3 and organic matter in enriching minor metals. The minor metals exhibit strong mutual positive association (R > 0.6 at 95% confidence level). The geographical distribution of the elements shows higher concentration in northern part of the study area when compared with their concentrations in the southern part. In view of the recent M9-tsunami effect on the coastal sediment of this region, the present investigation provides immediate pre-tsunami minor metal distribution levels. This in turn will provide a reference for studying sediment re-distribution due to high energy tsunami tidal waves in the study region.

[Key words: East coast of India, surface sediment, geochemistry, minor metals]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 279- 284

 

 

Interpretation of gravity data over the 85 °E ridge and Afanasy Nikitin
seamount using spectral method

 

A.R. Bansal & V.P. Dimri*

National Geophysical Research Institute, Uppal Road, Hyderabad – 500 007, India

[*E-mail:vpdimri@ngri.res.in]

 

The 85 °E ridge is an enigmatic buried aseismic ridge having the peculiar negative gravity anomaly in the north and positive anomaly in the south. Different theories are proposed for the negative anomaly over the 85 °E ridge. High-resolution two-dimensional satellite gravity data over 85 °E ridge is interpreted using the spectral analysis method covering the area from 5°S to 18 °N. The area consists of the Afanasy Nikitin seamount, partially buried hills and the 85 °E ridge. Twelve overlapping blocks of 3°΄3° are selected to calculate the depth of anomalous sources. The two layers of anomalous sources are observed for all blocks. The different depth values of causative sources are found for different portion of the
85
°E ridge. The deeper depth values for each block are representing the crustal thickness. The maximum thickness of 25.6 km was found for block 10 covering the area between latitude 12 °N to 15 °N. The average crustal thickness decreases from north to south along 85° E ridge. The reason of negative free air gravity anomaly below the 85 °E may be due to the depression in the Moho.

[Key words: Gravity data, 85 °E Ridge, Afanasy Nikitin Seamount, spectral method, crustal thickness]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 285 - 298

 

Utility of natural generalised inverse technique in the
interpretation of dyke structures

 

M.M.Malleswara Rao1*, T.V.Ramana Murty1, P.Rama Rao2, S.Lakshminarayana1,
A.S. Subrahmanyam1 & K.S.R.Murthy1

        1National Institute of Oceanography, Regional Centre, Visakhapatnam-530 017, India

        2Geophysics Department, Andhra University, Visakhapatnam – 530 003, India

[*E-mail: mmmrao@darya.nio.org]

Received 15 March 2004, revised 19 May 2005

Forward and Inverse methods of magnetic interpretation have been used to estimate the parameters of dyke like intrusion over the eastern continental shelf of India. In the forward problem, the tentative parameters of the causative source are assumed and anomalies are calculated using the anomaly equation, while inverse problem refers to methods of tracing the boundaries or outlines of anomalous bodies using an iterative approach. While solving the inverse problem, data kernel has been generated through the model (i.e. partial derivatives of magnetic anomaly function with respect to model parameters at each station forming the kernel). In solving the coupled eigenvalue problem of covariance matrices of data kernel, Singular Value Decomposition (SVD) has been performed to build Generalised Inverse Operator (GIO). This GIO is operated on the observed anomaly (with reference to the calculated) to yield improved model parameters. Data and model resolution matrices are computed to check the correctness of the solution and further analysis. The marine magnetic total field anomaly of continental shelf of Visakhapatnam is interpreted using GI technique, which revealed the causative source of the anomaly as a dyke model at a depth of 120 m below seabed.

[Key words: Magnetic anomaly, forward problem, inverse problems, GIO, SVD, data resolution, model resolution, closeness ratio, dyke intrusive, Visakhapatnam.]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 299 - 309

 

Subareal wave pressures, layer thicknesses, run-up and

run-down velocity on sea walls

 

S. Neelamani*

Department of Hydraulics and Coastal Engineering, Leichtweiss Institute for Hydraulics,
Technical University of Braunschweig, Beethovenstr: 51a, 38106 Braunschweig, Germany

 

Received 14 June 2004; revised 26 April 2005

Wave pressures, layer thickness, run-up and run-down velocities were measured on the splash/subareal zone (the part of the seawall which is partially in water during run up and partially in the air during run down) of plane seawalls for a wide range of hydrodynamic parameters and seawall slopes. The complete wave breaking range (spilling, plunging, collapsing and surging) is covered in the study. The maximum wave pressure in the subareal region can be as high as 1.2 times the static pressure due to water column equal to the incident wave height. The maximum wave pressure at any point is higher than the water pressure induced by the layer thickness due to the dynamic contribution of the flowing water on the seawall. The maximum run up and run down velocity can be as high as 25 times the maximum horizontal water particle velocity in deep water. The run-down velocity is found to be higher than the run-up velocity for the same input condition. Using the measured data, empirical formulae are proposed to predict the subareal wave pressures, layer thicknesses, and run-up and run-down velocities. The proposed formulae incorporate the surf similarity parameter and relative elevation of the location on the subareal region of the seawall. The empirical equations are simple, reliable and hence can be used for the optimal design of plane seawalls.

[Key words: Sea wall, wave pressures, layer thickness, run-up and run-down velocity, surf similarity parameter, subareal region]

 

[IPC Code: Int.Cl.7 E02B3/06]

           

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 310 -315

 

Mangrove mapping and change detection around Mumbai (Bombay)
using remotely sensed data

V. Vijaya, R. S. Biradara, A. B. Inamdarb, G. Deshmukhea, S. Bajib & Madhavi Piklea

                                aCentral Institute of Fisheries Education (ICAR), Versova, Mumbai-400 061, India

bCentre of Studies in Resources Engineering, Indian Institute of Technology, Bombay,

Mumbai 400 076, India

*[E-mail : rbiradar@hotmail.com]

Received 21 April 2004, revised 19 April 2005

Remote sensing technology was used to detect changes in the mangrove habitat around the Mumbai suburban region. For this purpose, cloud free satellite images on the scale of 1 : 50,000 from Indian Remote Sensing (IRS) satellite IRS-ID and IRS-IC were used. The total area of mangroves in Mumbai suburban region has been estimated to be 56.40 km2 (including mud flats) with dense mangroves contributing 45.4% to the total. During 1990 to 2001, a total mangrove area of 36.54 km2 was lost, indicating a 39.32% decrease in the area of mangroves. It has been observed that the quantitative degradation of mangrove vegetation is largely due to burgeoning population pressure, construction and development activities, conversion to agricultural land and fish farms besides the effect of industrial effluents. Avicennia marina was found to be the most dominant mangrove species. Measures have been suggested for conservation and management of mangroves of Mumbai on a sustainable basis.

[Key words : Mangrove, mapping, remote sensing, change detection]

 

 

Indian Journal of Marine Sciences

Vol. 34(3), September 2005, pp. 316 -319

 

Short Communication

 

Isolation of antagonistic marine bacteria from the surface of the gorgonian corals at Tuticorin, south east coast of India

 

*K. Mary Elizabeth Gnanambal, C. Chellaram & Jamila Patterson

Suganthi Devadason Marine Research Institute, No: 44, Beach Road, Tuticorin- 628 001,

Tamil Nadu, India

*[E-mail:maryelzi77@yahoo.com]

Received 28 September 2004, revised 9 March 2005

Culturable heterotrophic bacteria present on the surface of two gorgonian corals, Subergorgia suberosa and Junceella juncea were isolated and the number of pigmented and non-pigmented strains was noted. The antagonistic effect of the marine isolates was tested against 8 human pathogens and 7 fish pathogens. It was observed that 82% (289) of the isolated bacterial strains were found to be non-pigmented and 61% (214) were identified as Gram-negative. Only 13% (46) of the isolated bacteria were found to be antagonistic against both human and fish pathogens. 74% (34) of the producer strains were found to be non-pigmented, however, mild antagonistic activity was found to be exhibited also by the pigmented strains. Percentage of Gram-negative strains showing activity was found to be 68% (145). All the indicator strains tested were inhibited by at least 10 of the antagonistic marine bacteria. A higher degree of inhibition was conferred by 3 of the isolates (G110, G111 and G113) with maximum zones of inhibition against Escherichia coli (5.5mm) by the strain G113. The strains showing higher degree of inhibition against human pathogens (G110, G111 and G113) showed potent inhibition against the fish pathogens too with maximum inhibition against Proteus mirabilis (5mm) by the strain G110. The symbiotic bacteria present on the surfaces of these gorgonian corals may yield novel metabolites.

[Key words: Bacteria, corals, Tuticorin, Subergorgia suberosa, Junceella juncea, symbiotic bacteria, antagonistic activity]

[IPC Code: Int. Cl.7 A01N  63/02]