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  Indian Journal of Marine Sciences

 

 

ISSN: 0379-5136             

 

CODEN : IJMNBF

VOLUME 33

NUMBER 3

SEPTEMBER  2004

 

 

CONTENTS

 

Papers

 

Stable block Toeplitz matrix for the processing of multichannel seismic data

215-219

Kirti Srivastava & V.P. Dimri

 

 

 

Designing bamboo wave attenuators for mangrove plantations

220-225

Halmar Halide, Richard Brinkman & Peter Ridd

 

[IPC Code : Int.Cl.7 E02B 3/04, 7/02, B27J]

 

 

Boric oxide in seawater derived magnesia

226-230

V. Martinac, M. Labor & N. Petric

 

[IPC Code : Int.Cl7, C01F 5/08, C04B 2/00]

 

 

 

Identification of the ribosomal proteins S20 and L10 from the amphioxus Branchiostoma belcheri tsingtaunese (Cephalochordata/ Branchiostomatidae)

 

231-237

Mei Liu, Shicui Zhang, Zhenhui Liu & Anlong Xu

 

 [IPC Code : Int.Cl7, C12N 15/12]

 

 

Prevalence of diarrhegenic serotypes of Escherichia coli in the Cochin estuary, along west coast of India

 

238-242

A. A. Mohamed Hatha, Abirosh Chandran & K.M. Mujeeb Rahiman

 

 

Screening of bacteria from sediments of coastal ecosystem, as potential sources of alpha linolenic acid

 

243-247

S. Pujari, R. Roy & S. Bhosle

[IPC Code : Int.Cl7 C12P 1/04,  C12Q 1/02]

 

 

Isolation of bioactive marine actinomycetes from sediments isolated from Goa and Maharashtra coastlines (west coast of India)

 

248-256

C.R. Kokare, K.R. Mahadik, S.S. Kadam & B.A. Chopade

[IPC Code : Int.Cl7  C12N 1/02  , C12Q 1/02]

 

 

Fossil record of marine manglicolous fungi from Malvan (Konkan) west coast of India

 

257-261

K.P.N. Kumaran, Mahesh Shindikar & Ruta B. Limaye

 

 

 

Distribution of phytoplankton in the coastal waters of east coast of India

262-268

V. Geetha Madhav & B. Kondalarao

 

[IPC Code : Int.Cl7 AO1]

 

 

Influence of post-harvest treatment on shelf life and agar quality in seaweeds Gracilaria edulis (Rhodophyta/Gigartinales and Gelidiella acerosa (Rhodophyta/ Gelidiales)

 

 

269-275

M. Ganesan, P.V. Subba Rao & B. Jha

 

[IPC Code : Int.Cl.C08B 37/12]

 

 

 

The seasonal toxicological profile of four puffer fish  species collected along Bengal coast, India

 

276-280

Somiranjan Ghosh, Alok K. Hazra, Shivaji Banerjee & Biswapati Mukherjee
 

[IPC Code : Int.Cl.G01N 33/12]

 

 

Evaluation of different sources of lipid and lipid levels in the diet of pearlspot Etroplus suratensis (Teleostei: Perciformes)

 

281-286

S. Ahmad Ali

[IPC Code : Int.Cl.7 A23L 1/30]

 

 

 

Distribution of certain ecological parameters and foraminiferal distribution in the depositional environment of Palk Strait, east coast of India.

 

287-295

M. Suresh Gandhi & G.V. Rajamanickam

 

 

Depositional environment and silting in the Sharavati estuary, central west coast of India        

 

296-302

V. S. Hegde, Kanchanagouri, D. Gosavi, P.T.Hanamgond, G.K. Huchchannavar, G. Shalini & M. S. Bhat

 

 

Short communications

 

Mosquito larvicidal potential of some extracts obtained from the marine organisms- prawn and sea cucumber

 

303-306

Narsinh L.Thakur, Sandhya P. Mainkar, Reena  A. Pandit & Madhavi M. Indap

 

 

Morphometry and length-weight relationship of obtuse barracuda Sphyraena obtusata (Cuvier) (Teleostomi/ Actinopterygii/ Sphyraenidae) from Bombay waters, west coast of India

 

 

307-309

A.K. Jaiswar, Pranaya K. Prida, S.K. Chakraborty & R. Palaniswamy

 

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 215-219

 

Stable block Toeplitz matrix for the processing of multichannel seismic data

Kirti Srivastava & V P Dimri

 

Computation of deconvolution operators in the case of single channel sectioned input/multichannel seismic data involves the inversion of a block Toeplitz matrix. The inversion of such a matrix poses several problems. It is well established that the error energy which measures the well posedness of the matrix is seen to decrease with an increase in the filter length. However, with an increase in filter length the condition number of the associated matrix increases. This means that there is a trade off between ill posedness and accuracy. The ill-posed problem has been made well posed by a process of (1) normalization of the block Toeplitz matrix and (2) by adding prewhitening parameter. The prewhitening parameter is taken as a few per cent of arithmetic or the geometric mean of the main diagonal of the block Toeplitz matrix. Application to a synthetic as well as field seismic data shows that the condition number of the associated block Toeplitz matrix is reduced by a process of normalization and adding prewhitening parameter. Further it is observed that the condition number is smaller when the prewhitening parameter is taken as a few per centage of geometric mean as compared to the arithmetic mean. Stabilizing the matrix following the above procedure will help in obtaining stable as well as accurate deconvolution operators.

 

[Key words: Toeplitz matrix, multichannel seismic, deconvolution, filter length]

 

 

 

Indian Journal of Marine Sciences

Vol. 33(3), September 2004, pp. 220-225

 

Designing bamboo wave attenuators for mangrove plantations

 Halmar Halide, Richard Brinkman & Peter Ridd

 

The design of a cost-effective method for attenuating wave energy to protect coastal mangrove plantations is examined. The design makes use of bamboo, a material that is strong, environment-friendly, and widely available and cheap in most developing countries. It is suggested that bamboo poles are pushed into the sediment offshore from the coastal mangrove plantation, presumably unconsolidated mud. In order to determine the performance in reducing incident wave energy, a numerical model was developed that is capable of predicting wave attenuation due to isolated cylinders of various spatial densities, i.e. number of bamboo per m2, and various diameters. A design in which an 8 cm bamboo diameter arranged within a density of 1 bamboo per m2 to 4 bamboos/m2 is shown to be the most economical way of attenuating 50% of incident wave energy, costing as low as US$ 22.5 per 1m length of coastal protection. This is significantly lower than conventional breakwaters, which cost over US$ 1,000/m. A field experiment on a mud-bank and review of various studies suggested that the bamboo embedment depth be no less than 60 cm to avoid dislodging and scouring, with 100 cm of bamboo protruding above the bed surface.

 

[Keywords: Coastal protection, wave attenuation, bamboo, numerical modeling, breakwaters, scouring, Keulegan-Carpenter number]

[IPC Code: Int.Cl.7 E02B 3/04, E02B 7/02, B27J]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 226-230

 

Boric oxide in seawater derived magnesia

 V. Martinac, M. Labor & N. Petric

 

The study has examined the possibility of application of the combined rinsing method used to rinse the precipitate of magnesium hydroxide obtained from seawater by substoichiometric precipitation with the addition of 80% of the stoichiometric quantity of the dolomite lime as the precipitation agent. The rinsing agent was distilled water with pH = 6.26 and alkalised distilled water with pH = 12.50. The product quality was established by determining the concentrations of MgO, CaO and B2O3 in the calcined magnesium oxide. The purpose of the study was to determine the operating conditions that might be used for production of good quality caustic magnesia from seawater, i.e. caustic MgO with a low B2O3 and CaO content. It has been noted that the contents of B2O3 and CaO in caustic magnesia from seawater are significantly reduced by this rinsing method, which is of considerable importance as the substoichiometric precipitation is much more economical than the overstoichiometric one in the so-called “wet phase”.

 

[Key words: Substoichiometric precipitation, rinsing method, boric oxide, seawater, magnesia ]

IPC Code: Int.Cl.7, C01F 5/08, C04B 2/00]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 231-237

 

Identification of the ribosomal proteins S20 and L10 from the amphioxus Branchiostoma belcheri tsingtaunese (Cephalochordata/Branchiostomidae)

 Mei Liu, Shicui Zhang, Zhenhui Liu & Anlong Xu

 

The complete cDNA and deduced amino acid sequences of the ribosomal protein S20 (AmphiS20) and L10 (AmphiL10) from the amphioxus Branchiostoma belcheri tsingtaunese are presented here. The AmphiS20 cDNA consists of 591 base pair (bp) and encodes a 121 amino acid protein with a calculated molecular mass of 13,621 Da. The putative protein shares 65.6%-86.6% identity to the known eukaryotic homologues including animals, plants and fungi. The AmphiL10 cDNA is 763 bp in length and encodes a 217 amino acid protein with a calculated molecular mass of 24,751Da. The deduced protein displays more than 65.4% sequence identity to its homologues examined. The high idenitity of AmphiS20 and AmphiL10 to their homologues from evolutionarily diverse organisms points to the remarkably conserved role these proteins play in ribosome structure and function. As house-keeping genes, determination of AmphiS20 and AmphiL10 will provide valuable normalizing tools for the study of transcriptional expression of other genes in amphioxus.

 

[Key words: Amphioxus, Branchiostoma belcheri tsingtaunese, ribosomal protein, S20, L10]

[IPC code: Int.Cl.7 C12N 15/12]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 238-242

 
Prevalence of diarrhegenic serotypes of Escherichia coli in theCochin estuary,
along west coast of India

A. A. Mohamed Hatha, Abirosh Chandran & K. M. Mujeeb Rahiman

 

Prevalence of indicators of faecal pollution such as faecal coliform and faecal streptococci were studied at the Cochin estuary. There was consistently high load of faecal indicator bacteria at all stations. Serotyping of E. coli revealed the presence of diarrhegenic serotypes of E. coli such as enteropathogenic E. coli (EPEC), enterotoxigenic E. coli (ETEC), enterohemorrhagic E. coli (EHEC) and uropathogenic E. coli (UPEC). The diversity of E. coli serotypes was particularly high as we were able to detect more than 40 serotypes. The E. coli serotypes also showed spatial and temporal variation. Characterisation of faecal streptococci revealed predominance of Streptococcus faecalis subspecies liquefaciens followed by enterococcus group and Streptococcus bovis. Seasonal variation in the prevalence levels of these organisms showed a higher load of the indicator organisms during the monsoon season, especially that of faecal streptococci indicating a higher land run-off during this period. The results of the present investigations reveal the high degree of faecal pollution in the Cochin estuary posing health hazard to those who use this system for fishing and recreation.

[Key words: Escherichia coli, faecal pollution, estuary, diarrhegenic serotypes]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 243-247

 

Screening of bacteria from sediments of coastal ecosystem, as potential
sources of alpha linolenic acid

S Pujari & R Roy  and S Bhosle

 

Marine bacteria, known to produce wide range of molecules that are beneficial to animals as well as to human beings, were screened for the presence of alpha linolenic acid (9,12,15-octadeca trienioc acid). The lipid and protein concentrations of predominant bacterial isolates, obtained from coastal marine sediment were determined. Out of twenty isolates, eight bacterial isolates with higher lipid – protein ratio (more than 0.5), were grown in mineral salt medium with sodium acetate as carbon source as well as in nutrient broth. Their lipid (triglyceride, sterol, fatty acid, glycolipid and phospholipid) and fatty acid (mainly C-18 series) profiles were analyzed. Only four bacterial isolates depicted significant conversion efficacy for alpha linolenic acid (more than 25%) when they were grown in sodium acetate media. Such bacteria can be used as supplement to enrich the animal feed with the required fatty acid.

 

[Key words: Linolenic acid, bacteria,  sediment]

IPC Code: Int. Cl.7 C12P 1/04, C12Q 1/02]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 248-256

 

Isolation of bioactive marine actinomycetes from sediments isolated from Goa and Maharashtra coastlines (west coast of India)

C R Kokare, K R Mahadik & S S Kadam   and B A Chopade

 

Twenty marine sediment samples were collected at the time of low tide from Maharashtra and Goa coasts in July 1999. Heat pretreatment at 41°C for 1 to 2 months was found to be most effective for the isolation of marine actinomycetes. Eight different selective media were used for isolation of actinomycetes and starch casein agar and glucose asparagine agar media prepared in natural seawater showed good growth of actinomycetes. Best growth of actinomycetes was observed at 28°C after incubation for three weeks. Significant differences were found between the counts of actinomycetes on different media. Out of 80 actinomycetes, 59 actinomycetes showed fast growth, 21 showed slow growth and 53 actinomycetes showed pigmentation of brown (5), gray (30), orange (2), black (8), yellow (4), red (2) and greenish (2) colors. Antibacterial and antifungal activities were tested using cross streak and cylinder plate technique. Out of 80 strains of actinomycetes, 35 showed bioactive activities. Out of 35 strains, 20 showed strong antimicrobial activity against different types of organisms and remaining 15 showed very weak antimicrobial activity. From these twenty strongly bioactive strains, 16 showed activity against Gram-positive, 2 against Gram-negative microorganisms and 7 showed antifungal activities. Out of these actinomycetes, 16 belonged to genus Streptomyces and one each to Streptoverticillium, Catellatospora, Nocardia and Actinopolyspora. Interestingly, Actinopolyspora and Catellatospora species were found in sediments and it shows good antimicrobial activity. Present study clearly indicates that sediment samples from Alibag, Janjira and Goa are potent sources for the isolation of bioactive actinomycetes.

 

[Key words: Marine sediment, pretreatment, selective media, pigmentation, antimicrobial activity, Maharashtra coast, Goa coast, Alibag, Janjira]

[IPC Code: Int. Cl.7   C12N  1/02,  C12Q 1/02 ]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 257-261

 

Fossil record of marine manglicolous fungi from Malvan (Konkan) west coast of India

K P N Kumaran, Mahesh Shindikar & Ruta B Limaye

 

The pneumatophore bearing lignites of Kolamb in Malvan (Maharashtra, west coast of India) have yielded a rich mycoflora of higher marine fungi. Out of a dozen hypomycetes known from the submerged parts of mangrove plants, more than 8 species have been retrieved from the lignite deposits, and as such indicate the potential for a mangrove association within the fossil deposits. Of the five marine species of genus Cirrenalia Meyers & Moore, four are associated with the pneumatophore bearing lignites of Kolamb. Monodictys pelagica (Johnson) Jones and Periconia prolifica Anastasiou are other hypomycetes recorded in the palynological preparations. As the morphological details and size of the conidia have striking resemblance to modern taxa, the fossils have been referred to corresponding taxa described from the mangrove habitats of the tropics. Thus, the fossil record of this mycoflora is of great significance and considerable importance, since it indicates fossil mangrove habitat, and as such complements the micro and megafossil data associated with the lignite deposit. Such evidence is important to infer palaeobiogeography and sea level along the west coast of India during the Late Tertiary (Neogene).

 

[Key words: Lignites, mangrove, pneumatophore, manglicolous fungi, fossil hypomycetes, Cirrenalia,    Monodictys, Malvan]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 262-268

 

Distribution of phytoplankton in the coastal waters of east coast of India

V.Geetha Madhav & B.Kondalarao

 

In the present study qualitative and quantitative distribution of phytoplankton with regional and seasonal variations in the coastal waters of east coast of India are presented out of the pooled data of 292 stations sampled during 12 cruises of FORV Sagar Sampada from 1999 to 2002. The study recorded 131 species of dinoflagellates, 111 species of diatoms and 7 species of Cyanophyta. Southeast coastal region has more endemic forms (34 species) than the northeast region (29 species). Quantitatively very low mean densities (1 to 367 nos l-1) are observed. Regionally, 143 species are present at all the latitudes between 11°N and 20°N. Seasonally, monsoon season recorded more number of phytoplankton (193) species. The study indicates the high diversity and low production of phytoplankton in the coastal waters of east coast of India.

 

[Keywords: Phytoplankton, coastal waters, east coast of India]

 [IPC Code : Int. Cl.7 AO1]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 269-275

 

Influence of post-harvest treatment on shelf life and agar quality in seaweeds Gracilaria edulis (Rhodophyta/Gigartinales and Gelidiella acerosa (Rhodophyta/Gelidiales)

M.Ganesan & P.V. Subba Rao and  B. Jha

 

The effect of acetic acid and alkali (KOH) pretreatments on the shelf life of Gracilaria edulis and Gelidiella acerosa were studied with respect to the agar yield and physical properties. Algae collected from the Gulf of Mannar, southeast coast of India were treated with 1) 0.5% acetic acid for 1 hr, 2) 1% KOH for 1 hr and 3) 0.5% acetic acid 1 hr followed by neutralization in 1% KOH for 1 hour. Gracilria edulis pretreated with acid + alkali gave the maximum agar yield (69.2 ± 12.3%), gelling temperature (50.5±1°C ) and melting temperature (82.5±1.5°C ). However no improvement in gel strength was recorded over control. Acid treated G.elidiella acerosa yielded the maximum agar (59.2 ± 3.9%) while exhibiting a gel strength of 295.1 ± 18.6 g.cm -2, a gelling temperature of 53 ± 2.5°C and a melting temperature of 88.7± 0.7°C . When the pretreated algae were stored for 4 months, for G.edulis agar yield remained same but its physical properties decreased gradually. In G.acerosa agar yield and melting temperature were constant, but gel strength and gelling temperature decreased drastically. It is suggested that agar industry can treat Gelidiella acerosa with acetic acid and Gracilaria edulis with acetic acid and KOH prior to storage. This will help to increase the agar yield and its physical properties on immediate use and maintain agar yield on long term use.

 

[Key words: Agar yield, gel strength, gelling temperature, melting temperature, acid, alkali, treatment, storage]

[IPC Code: Int. Cl.7 C08B 37/12]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 276-280

 

The seasonal toxicological profile of four puffer fish species collected
along Bengal coast, India

Somiranjan Ghosh, Alok K. Hazra, Shivaji Banerjee & Biswapati Mukherjee

 

Toxicological profiles of the livers and ovaries of four Indian marine puffer fish species viz. Chelonodon patoca, Takifugu oblongus, Lagocephalus lunaris, Lagocephalus inermis collected along coastal Bengal of Digha-Talsari region were evaluated by mouse bioassay. Toxicity expressed in MU (mouse unit)/g in ovaries of all four species were high in monsoon (13.9 – 80 MU/g) and postmonsoon (8.9 – 136 MU/g) seasons during annual reproductive cycle. However, toxicity of livers was much lower (3.2 – 18.5 MU/g) in all the species with seasonal variation. Chelonodon patoca specimens were found to be most toxic and Lagocephalus inermis were least toxic in comparison to other species under investigation. Therefore, health hazard due to puffer fish consumption could be minimised by the information given in this study regarding lethality.

 

[Key words : Puffer, toxicity , Chelonodon patoca, Takifugu oblongus, Lagocephalus inermis, Lagocephalus lunaris, fish]

[IPC Code: Int. Cl.7 G01N 33/12]

 

 

 

 Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 281-286

 

Evaluation of different sources of lipid and lipid levels in the diet of pearlspot Etroplus suratensis (Teleostei: Perciformes)

 S Ahamad Ali

 

Seven different oils namely, coconut oil, cod liver oil, gingely (sesame seed) oil, groundnut oil, sunflower oil, soybean oil and sardine oil were evaluated in the diet of pearlspot (Etroplus suratensis). These oils were individually incorporated at 7% level in an iso-nitrogenous diet consisting of a protein base, other ingredients and binder. In the second experiment, a mixture of coconut oil and sardine oil (which gave the best results in the first experiment) in the ratio of 1 : 1 was prepared to study the effect of dietary lipid levels on growth of pearlspot. Seven more iso-nitrogenous diets were formulated with the above mixed lipid supplementation of 0 to 15%.The results of the 35-day feeding trial with test diets having different lipid sources showed that the fish (initial weight 15-20 g) fed with diet containing coconut oil led to significantly (P<0.05) higher weight gain of 23.91±1.92 g followed by the diets with sardine oil (19.2±0.89 g), cod liver oil (19.15±1.24 g), gingely oil (16.52±0.66 g) and the control diet led to a weight gain of 19.24±0.59 g. The specific growth rate also followed similar trend. The weight gain of fish fed with diets having groundnut oil, sunflower oil and soybean oil is marginally less than that of the control diet indicating that dietary addition of these oils had no beneficial effect on growth. The diet with coconut oil led to significantly (P<0.05) lower FGR (1.60) followed by that containing cod liver oil (1.96) and sardine oil (2.0). The growth of fish increased, feed gain ratio (FGR) and protein efficiency ratio (PER) improved with increase in lipid supplementation in the diet up to 5%. The diet with a total lipid content of 8.6%(with 5% supplementation) gave significantly (P<0.05) higher weight gain (18.24±0.84 g), specific growth rate (1.0590) and lowest FGR (1.6). This diet also gave significantly (p<05) better PER (1.94). Further increase in the lipid supplementation in diet had negative effect on growth, SGR, FGR and PER. The results obtained in this study can be utilized for formulating practical feeds using appropriate lipid sources for feeding pearlpsot for its aquaculture. This study also leads to further investigations on more specific dietary fatty acid requirements of Etroplus suratensis

 

[Key words: Lipid, diet, pearlspot, growth, feed gain ratio, Etroplus suratensis, fatty acids]

[IPC Code: Int. Cl7. A23L 1/30]

 

 

 

Indian Journal of Marine Sciences

 Vol. 33(3), September 2004, pp. 287-295

 

Distribution of certain ecological parameters and foraminiferal distribution in the depositional environment of Palk Strait, east coast of India

M.Suresh Gandhi and G.V Rajamanickam

 

Out of 102 species, only 36 species are living ones. The total distribution of foraminifera is higher at Devipattinam and Attankarai followed by Mandapam, Thondi and Kodiyakkarai whereas at Kottaipattinam, Manalmelkudi and Sethubavachattiram it is noticed to be in the lower order. Organic matter and living species show positive relation. The lack of relationship between dead species and the organic matter has suggested that the dead species recorded in the sediments must have been primarily drifted/transported as empty calcareous shells. From the sand/silt/clay ratios, it is inferred that the sediments are normally sandy in nature but silty sand dominates at deeper depths. Carbonate content establishes a weak negative correlation with all parameters except organic matter and dead species. Fluctuation of salinity values in Attankarai indicates the influx of fresh water from Vaigai river. Based upon the ecological parameters the stations have been grouped into different environments. Among them, bar environment registers low species diversity than the other three. The following species are appreciably distributed in different stations namely Ammonia beccarii, Elphidium crispum, Rosalina globularis, Asterorotalia trispinosa, Osangularia venusta and Pararotalia nipponica. This strait is influenced by an unique environment of high order of siltation leading to the depletion of living forams. The present study highlights the abundance of living species in places of high organic matter. The ongoing process of active siltation is manifested in the bar environment and the same is reflected in the low organic matter and less species diversity.

 

[Key words: Benthic foraminifera, siltation, organic matter, carbonate, Palk Strait]

 

 

 

Indian Journal of Marine Sciences

   Vol. 33(3), September 2004, pp. 296-302

 

Depositional environment and silting in the Sharavati estuary, central west coast of India

V S Hegde, Kanchanagouri, D Gosavi, P T Hanamgond,

G K Huchchannavar,  G Shalini, & M S Bhat

 

Variation in textural characters (silt sand ratio, mean size, sorting and skeweness) of the Sharavati estuarine sediments has been studied to understand their depositional environment. Seventeen locations within the estuary and two locations just at the entrance of the sea were selected for the study. During September 2000, medium grained (1.36-1.86f), well sorted to moderately well sorted sediments were observed in the estuary, whereas they were fine grained (2.67-3.f) and poorly sorted in the entrance of the sea (0.84). The estuarine sediments were relatively fine-grained during December 2000 (postmonsoon) (1.3-2.18f) and February 2001(premonsoon) (1.15-2.3f) as compared to the monsoon season. The siltation in the estuary is mainly due to offshore source brought by tidal currents followed by mixing of saline and fresh water in the estuary.

 

[Key words: Estuary, silting, depositional environment, texture, Sharavati river]

 

 

 

Short  communications

 

Indian Journal of Marine Sciences

Vol. 33(3), September 2004, pp. 303-306

 

Mosquito larvicidal potential of some extracts obtained from the marine
organisms¾ prawn and sea cucumber

Narsinh L Thakur, Sandhya P Mainkar, Reena A Pandit & Madhavi M Indap

 

The larvicidal potential of two marine organisms was investigated by testing their non-polar to polar organic extracts against mosquito Culex pipens fatigans. In the present investigation the non-polar petroleum ether extract of prawn Nematopalaemon. tenuipes, Hendersen and polar methanol extract of sea cucumber Holothuria scabra, Jaeger body wall were found to be effective against mosquito larvae. The preliminary chemical analysis showed the presence of steroids in the active extract of prawns, whereas the presence of saponins in the active extract of sea cucumber body wall. In this context, the observed mosquito larvicidal activity could be attributed to the presence of steroids and saponins. In summary, this investigation explores the importance of marine organisms as a valuable resource for the discovery of novel insecticidal molecules.

 

[Key words: Nematopalaemon tenuipes, Holothuria scabra, Culex pipens fatigans, larvicidal activity, prawn, sea cucumber]

 

 

 

Indian Journal of Marine Sciences

Vol. 33(3), September 2004, pp. 307-309

 

Morphometry and length-weight relationship of obtuse barracuda Sphyraena obtusata (Cuvier) (Teleostomi/Actinopterygii/Sphyraenidae) from
Bombay waters, west coast of India

 A K Jaiswar, Pranaya K Parida, S K Chakraborty & R Palaniswamy

 

The morphometric and meristic studies on obtuse barracuda Sphyraena obtusata from Mumbai (Bombay) waters indicated allometric relationship and high degree of homogeneity within the population. Based on the present study, the fin formula can be written as B. vii, D. 5, 1/9, P. 14, V. 1/5, A. 2/9, C 17, Ll. 90-95, two gill rakers on the first gill arch. Variations observed in some of the meristic counts when compared with findings from different locations indicate the presence of different stocks. The length-weight relationship for the species from the Mumbai waters is estimated to be W = 0.0000245L2.7226. Deviation in the growth rate “b” observed during the present investigation from that of other countries and different region in India itself is result of variations in ecology of these geographical locations.

 

[Key words: Morphometry, meristic characters, length-weight relationship, barracuda