Showing papers in "Indian Journal of Marine Sciences in 2002"

Trace metals concentrations in the sediment cores of estuary and tidal zones between Chennai and Pondicherry, along the east coast of India

Abstract: Four sediment cores collected from the water depths varying between 1.0 and 1.50 m in estuarine and tidal zones between Chennai and Pondicherry, along the Tamil Nadu coast, were analysed for major elements (Fe and Al), trace metals (Mn, Zn, Cr, Co, Pb and Ni), carbonate and organic carbon contents to understand the behaviour of trace metals and their probable sources. The results reveal that Ni and Cr are higher in the Adyar estuarine sediments compared to other three sites at Muttukadu, Mamallapuram and Marakkanam. Higher content of Ni and Cr in the entire core sediments of Adyar points to mixing of sediments and bioturbation. Calculated enrichment factor (EF) with respect to upper continental crust (UCC) values show that analysed sediments are depleted in Mn, Co, Pb and enriched in Ni, Cr. Adyar estuary is highly contaminated especially with respect to Ni and Cr due to metal inputs from anthropogenic activity. Higher Fe and Mn content in Mamallapuram sediments may be due to the variability of source rock exposed in this region. The EF values of Marakkanam sediments reveal unpolluted nature and the positive correlation among Fe, Mn and other trace metals indicate the influence of early diagenetic process.

Mangroves along the coastal stretch of the Bay of Bengal: Present status

Abstract: With the help of high resolution satellite data (SPOT products), it has been possible to portray on maps the present distribution of main mangrove types and sub-types of the Bay of Bengal coastline. New figures have been given for the mangroves of each concerned country especially for Myanmar. The present ecological status of mangrove ecosystems in the three major deltas, the Godavari, the Ganges and the Irrawaddy are totally distinct. In the Godavari delta (India) mangroves are receding in area and biomass; in the Ganges, the Sunderbans (India and Bangladesh) are evolving very slowly in size but an important species substitution is in progress; in the Irrawaddy (Myanmar) mangroves are in continuous decline. The present distribution and status of each mangrove type is the result of direct and indirect anthropic factors. Conversion to agriculture, reafforestation, fishponds constructions, forest exploitation are now easily detected from space. Conversely, indirect impacts, such as freshwater diversion or chemical pollution, cannot be monitored with sensors operating in the visible part of the electromagnetic spectrum.

Endophytic fungi associated with the tropical seagrass Halophila ovalis (Hydrocharitaceae)

Abstract: Leaf blade, petiole and rhizome of the seagrass Halophila ovalis were examined for the presence of endophytic fungi. Although the seagrass harboured endophytic fungi, their number and colonization densities in seagrass tissues were low. This is presumed to be due to a combination of physical and chemical factors.

Antimicrobial substances of potential biomedical importance from holothurian species

Abstract: Antibacterial and antifungal activities of alcoholic extracts of holothurian species such as Actinopyga echinites, A. miliaris. Holothuria atra and H. scabra of Tamil Nadu coast were studied. Bacteria such as Aeromonas hydrophila, Escherichia coli, Enterococcus sp., Klebsiella pneumoniae, Pseudomonas aeruginosa, Salmonella typhi, Staphylococcus aureus and Vibrio harveyi, and fish-borne mold, Aspergillus sp. were inhibited at varying levels by the extracts of A. miliaris, H. atra and H. scabra. Bacillus sp. was not affected by holothurian extracts. The results of the study revealed the presence of antimicrobial substances possibly steroidal sapogenins in holothuria. There exist a great potential for the extraction of bioactive substances of medical importance at a lower cost from marine holothurians.

Antimicrobial activity in the tissue extracts of five species of cowries Cypraea spp. (Mollusca: Gastropoda) and an ascidian Didemnum psammathodes (Tunicata: Didemnidae)

Abstract: Five species of Cypraea (Cypraea errones, C. arabica, C. onyx, C. tigris and C. vitellus) were assayed for their antibacterial and antifungal activity against 15 bacterial pathogens and 3 fungal pathogens. Antibacterial and antifungal activities were exhibited only by C. errones extracts. An ascidian, Didemnum psammathodes, the principal diet of C. errones was also assayed for antimicrobial activity to evaluate whether the activity exhibited by C. errones was derived from its diet. The ascidian extract exhibited broad-spectrum antibacterial activity. Chromatographic fractionation of the extracts of C. errones and Didemnum psammathodes confirmed that the activity exhibited by C. errones was not diet derived.

Variations in hetetrophic and phosphate solubilizing bacteria from Chennai, southeast coast of India

Abstract: Estuarine and open coastal biotopes along the Chennai coast were sampled bimonthly for total heterotrophic as well as phosphate solubilizing bacteria (PSB) between January and December 1999. THB was high during months January, September and November. THB population ranged from 6.03 - 8.13 x 10 5 cells ml -1 and phosphate solubilizing bacterial population from 1.00-1.3 x 10 3 cells ml -1 . Pseudomonas and Bacillus were found to solubilize more phosphates than others. Further the phosphate solubilizing potential of Pseudomonas was confirmed in broth cultures where P solubilization was 1700 μg/ml -1 associated with reduction of pH.

Metal concentrations in five mangrove species of the Bhitarkanika, Orissa, east coast of India

Abstract: The study deals with metal concentrations in five mangrove species Rhizophora mucronata, Avicennia officinalis, Bruguiera cylindrica, Ceriops decandra, and Xylocarpus granatum with regard to the heavy metals like Fe, Cu, Mn, Zn and major elements like Na, K, Ca. The metallic concentrations were analysed in sediment samples collected from surrounding root zone of mangrove species and in the leaves of the same plant. Avicennia officinalis accumulated high concentrations of all the metals analysed, followed by X. granatum, B. cylindrica, R. mucronata and C. decandra. The samples collected during the monsoon period (26 th August 1996) showed high metallic concentrations than the samples of post-monsoon (10 th January 1997) and pre-monsoon (11 th April 1996) period.

Textural and trace elemental distribution in sediments of the Beypore estuary (SW coast of India) and adjoining innershelf

Abstract: The Beypore estuary, situated in Kerala along the southwest coast of India, receives large volumes of untreated/partially treated industrial effluents, municipal sewage and wastes. Concentrations of trace elements (Mn, Cr, Zn, Ni, Cu, Pb and Co) in 52 surficial sediment samples collected from the Chaliyar River, the Beypore estuary and the adjoining innershelf region are presented here. Textural characteristics, major elements and total organic carbon (TOC) content of the sediments have substantial influence on the elemental distribution. Significant variations in the concentrations of Mn, Cr, Zn, Ni, Cu, Pb and Co were observed in riverine and estuarine sediments whereas except for Mn, the variations are not so pronounced in the innershelf region. Both silt and clay show high positive loadings with all the elements in the estuarine region. However, in the innershelf sediments, the trace elements show better affinity with clay fraction than silt. TOC has significant positive correlation with trace elements in both estuarine and innershelf sediments. Trace elements are also associated with Fe, Al and Mn. Finer fractions and TOC played a major role in the distribution and retention of trace elements in the sediments. Except Cu, all the other trace elements showed considerable enrichment beyond st. 13 (downstream of effluent discharge point from the rayons factory), indicating the effect of industrial effluents on their incorporation in the sediments. Estuarine input has a profound influence on the trace metal flux in the immediate vicinity of the adjoining innershelf.

Isolation of marine bacteria, antagonistic to human pathogens

Abstract: Pigmented bacteria from marine samples including seawater, sediment, seaplants, bivalves and submerged substrates of the Tuticorin coast were screened for the antibacterial activity. Of the 162 pigmented bacteria, 62 exhibited antagonism towards the indicator organisms Lactobacillus, Arthrobacter and Micrococcus. Alteromonas was the dominant antagonistic marine bacteria, exhibiting a wide antibacterial spectrum against the human pathogens associated with seafoods such as Staphylococcus aureus, Salmonella typhi and Vibrio cholerae. Results indicated that antibacterial substances present in the antagonistic marine bacteria could be used to inhibit the growth of human pathogens.

Macrobenthic communities of the coastal waters of Dabhol, west coast of India

Abstract: Macrobenthic community of a shallow subtidal (5-20 m) muddy deposit off Dabhol was investigated. Sediment comprised mainly of silt and clay with less of sand. Dominance of clayey-silt fraction reflects on active flocculation of fine grain particles. The sediment organic carbon with a mean value of 1.42% was rather high. The population density of macroinvertebrates varied from 250 to 600 no.m -2 (mean=395±111) during December 1994. The values increased significantly during December 1996 and ranged between 400 and 975 no.m -2 (mean = 621±194). Macrofaunal community comprised of typical near-shore species, numerically dominated by polychaetes. The sediment organic content reflects on the high biological productivity of the area, particularly benthic production that was evident from a good fish catch in the experimental bottom trawling. Values for species diversity followed more or less similar trends and less variability among the sampling stations in Dec.1994 and Dec. 1996. However, species composition indicated the dominance of different taxa among the sampling locations during two sampling years. The occurrence of juvenile forms of decapods (shrimps and crabs) in the benthic samples suggest that the coastal waters of Dabhol provide favourable environmental conditions for feeding and breeding of commercially important prawn and crab species.

Distribution of sediment nutrients of Vellar estuary in relation to shrimp farming

Abstract: Shrimp farming picked up fast in India particularly in the southern states, due to promotion on the part of Government agencies and high return on investment (ROI). The discharge of used water from the shrimp farms into the estuaries, backwaters and mangroves became a matter of great concern of the environmentalists. In the absence of reliable data collected over a period of time, no definite conclusions could be drawn about the negative impact of shrimp farming. This emphasized the imperative need for monitoring different physico-chemical and biological parameters of the estuaries, backwaters and mangroves where shrimp farming has a strong presence. In the Vellar estuary (lat.11°29′N; long. 79°46′E) shrimp farms were started in the year 1992 and by 1995, there were as many as 42 shrimp farms with a water spread area of 150 ha. The formulated pellet feed given to the shrimp is rich in protein, fat, fibre and minerals etc. These nutrients get dissolved in water, settle in the sediment of the shrimp farms and discharged into the Vellar estuary during periodic draining. Estimation of the levels of nutrients can serve as indicator of enrichment and eutrophication in the estuary arising out of shrimp farming. Therefore in the present study, data on levels of carbon, nitrogen and phosphorus in sediments were collected for a period of two years with the view of ascertaining changes in their levels arising out of discharge of used water from shrimp farms into the estuary.

Quantification of halophilic Azospirillum from mangroves

Abstract: the rate of nitrogen fixation in Azospirillum brasilense were found to be maximum at pH 7.0. At 3 % NaCl, it showed better growth and production of IAA, however the rate of nitrogen fixation was slowed down at 1 % NaCl and was completely arrested at 1.5 %. The percentage of germination in coastal crop plants increased by 70 % in black gram and 45 % in rice with the inoculation of Azospirillum brasilense compared with control. The saline tolerant Azospirillum is recommended as biofertilizer for improving crop yield in coastal agricultural fields Mangroves represent a unique and ecologically important coastal habitat in the tropical and subtropical belts and are frequently seen as pioneer vegetation in coastal area 1 . A number of static and dynamic biological, physical and chemical factors are known to influence the development and stability of a mangrove community. These factors and their interactions play a significant role in the nutrient flows in the system and it becomes necessary to understand the various proc

Epiphytic bryozoan community of Posidonia oceanica (L.) Delile meadow in the northern Cyprus (Eastern Mediterranean)

Abstract: Bryozoan communities occurring on leaves and rhizomes of Posidonia oceanica (L.) Delile, in seven meadows along the northern coast of Cyprus from 3 and 10 m depths were studied in July 1998. Forty-three epiphytic bryozoan species (5 Ctenostomata, 32 Cheilostomata, 6 Cyclostomata) were found. Crisia ramosa was recorded for the first time in the Eastern Mediterranean Sea while 6 species showed restricted biogeographical distribution. The epiphytic species are qualitatively richer on the rhizomes compared to those noted on leaves.

Abundance of indicator and general heterotrophic bacteria in Port Blair bay, Andamans

Abstract: Viable counts of indicator and general heterotrophic bacterial populations were enumerated from 6 stations in Port Blair bay during different seasons. High counts of coliforms and indicator bacteria were generally recorded in the Aberdeen zone of Port Blair bay. Other zones in the bay showed few, if any, coliforms or indicator species during non-monsoon periods. During periods of intensive rainfall, the entire bay waters showed positive results for Vibrio cholerae, Vibrio parahaemolyticus, Streptococcus faecalis and Escherichia coli like organisms. Pseudomonas aeruginosa was mostly absent, except during a dinoflagellate bloom when counts as high as 10 2 CFU ml -1 were recorded. Viable heterotrophic bacteria showed a specific pattern of variation in which the numbers decreased progressively from the entry channel to inner portions of the bay. On the whole, results point to the large probability of coastal water contamination from rainwater runoff effects.

Decomposition and seasonal changes in nutrient constituents in mangrove litter of Sundarbans mangrove, Bangladesh

Abstract: Decomposition of Heritiera fames, Xylocarpus mekungensis, Bruguiera gymnorhiza and Avicennia officinalis leaf and non-leaf litter was studied using litter bag in Sundarbans reserve forest. During 45 days decomposition experiment both in field and lab, 43-78% weight loss of fresh mass was recorded. Proximate and micro-nutrient concentrations were similar among different classes of leaf and non-leaf litter. Concentrations of nutrient constituents were higher during the monsoon, and winter showed the highest level of heavy metal concentrations in mangrove litter of Sundarbans. Decomposition of mangrove litter resulted in a decrease in lipid content, and increased the metal concentrations, than fresh one.

Cultivation of marine red alga Gracilaria edulis (Gigartinales, Rhodophyta) from spores

Abstract: Gracilaria edulis, a major Indian agarophyte, has been successfully cultivated in an experimental scale from spores at sea off Narakkal, Kochi. Artificial objects like floating raft, nylon ropes and net pieces were provided in the open sea for collection of spores of Gracilaria edulis. They were allowed to grow to mature size of 30 cm. After 76 days of culture period, fully grown healthy plants of Gracilaria edulis were harvested from the nylon rope by hand pruning. Further growth was much faster. A total yield of 7.220 kg plants was obtained during 122 days of the culture period. The work has resulted in the successful cultivation of the species from the east coast to a coastal area of the west coast, Narakkal, and also in the identification of a fertile culture ground (open sea off Narakkal, Kochi) along the Kerala coast during favourable period of growth.

Oyster species of the sub tropical coast of Pakistan (northern Arabian Sea)

Abstract: In the present study 9 species of oysters belonging to three genera (Crassostrea, Saccostrea and Ostrea) were identified on the basis of their conchological and malacological features. These included Crassostrea gryphoides, C. madrasensis, C. belcheri, C. glomerata, Saccostrea cucullata, S echinata, Ostrea nomades, O. folium and O. cristagalli. Two species Ostrea nomades and O. cristagalli which are being reported for the first time from Pakistan. Crassostrea gryphoides and C. rivularis from Hub River Delta were earlier treated as separate species have been assigned to a single species C. gryphoides. Crassostrea gryphoides and C. madrasensis, which occur in the same habitat and show marked similarity in their external shell morphology, but differ in the colouration of their adductor muscle scar, are treated here as separate species.

Screening of codiacean algae (Chlorophyta) of the Indian coasts for blood anticoagulant activity

Abstract: Thirteen species of marine algae belonging to the family Codiaceae were selected from the Indian coast to study their sulphated polysaccharide (SPS) contents and their blood anticoagulant activity. The algal species studied include Codium dwarkense, C. tomentosum, C. indicum, C. geppei, C. iyengarii, C. coronatum, C. tenue, C. decorticatum, Udotea indica, U. flabellam, Halimeda tuna, H. gracilis and Avrainvillea erecta. Cold and hot water extracts were prepared from all the species and chemical compositions (e.g. total sugar, sulphate, protein and uronic acid contents) were analysed. All the SPS samples were screened for their blood anticoagulant activity (PT test). It was observed that blood anticoagulant activity (cf. Codium spp.) is generally higher with samples containing higher sugar and sulphate contents. Neutral sugar composition was analysed and active extract was found to contain relatively more arabinose. Seasonal variation in chemical composition and blood anticoagulant activity of the SPS of C. dwarkense were also studied alongside. It was observed that matured plants showed higher activity than the younger ones and arabinose was detected in higher quantity in the former. This work reveals that a few Codium species e.g. C. dwarkense, C. indicum and C. tomentosum, C. geppi produce strongly active blood anticoagulant SPS while the ones obtained from the other Indian Codiaceae species under investigation exhibit very low activity.

Role of natural productivity in modified extensive shrimp pond growing Penaeus monodon (Penaeidae, Crustacea)

Abstract: Hydrobiology of a modified extensive shrimp (Penaeus monodon) culture pond was monitored. Qualitative and quantitative analyses of plankton population revealed higher phytoplankton population during the first six weeks of culture which declined to low level thereafter and remained at that level till the end of the culture period. Zooplankton was represented mainly by rotifers, copepods and mysids. Dense population of rotifers and copepods occurred during the first-month of culture while mysids appeared from the third week of first-month and dominated there after. Composition of zooplankton varied depending on the occurrence of Brachionus plicatilis, Keratella spp, Pseudodiaptomus annandalei Paracalanus aculetaus, Oithona brevicornis, Microstella norvegica and Mesopodopsis zeylanica during the culture period. Gut content analyses showed sand grains, zooplankton, pelletized feed and unidentified semi-digested food matter in the proportions of 43%, 16%, 21% and 20% respectively. The percentage of stomach contents varied in different size groups. It is observed that during the early phase of culture natural food contributes considerably to the growth of the shrimp.

Seasonal growth pattern in Sargassum polycystum C. Agardh (Phaeophyta, Fucales) occurring at Visakhapatnam, east coast of India

Abstract: Sargassum polycystum is a conspicuous component of the intertidal algal flora of Visakhapatnam coast. Seasonal growth pattern of this brown alga was studied, collecting data on mean thallus length, mean number of primary shoots, frequency of different size classes and reproductive condition as well as on some environmental factors for two years (November 1994 to October 1996). This alga showed marked seasonality, commencing its growth from April/May every year and attained its maximum length in the winter months (November to December/January). Maximum number of primary shoots and higher frequency of larger size classes were also noticed during the winter season. The seasonal growth showed significant negative correlation with temperature, indicating it as a causal factor for seasonality than the other environmental conditions.

Wave forces on a vertical cylinder defenced by a perforated vertical and inclined barriers

Abstract: Wave forces on a vertical cylinder defensed by a perforated vertical and inclined barriers with 45° angle of inclination were experimentally investigated. The relative wave height, (H i /d) varied from 0.114 to 0.429 and the porosity was kept constant with 12%. The force ratios were found reducing with increase of H i /d. It is estimated that on an average, the reduction of force on the vertical cylinder is about 35% due to perforated vertical barrier and is about 30% due to sloped barrier. Incident wave steepness, (H i /L) varied from 0.007 to 0. 080 and the force ratios were also found reducing with increase of wave steepness. The force ratios are less sensitive for the scattering parameter (ka).

Biochemical composition of zooplankton from Visakhapatnam harbour waters, east coast of India

Abstract: Proximate composition, zooplankton biomass, protein, lipid, carbohydrate, organic carbon and calorific content of mixed zooplankton in the Visakhapatnam harbour waters were estimated. Biomass varied from 15.2 to 74.0 ml.100 m -3 (X =31.05 ±17.7) in the outer harbour and 10 to 64.0 ml.100 m -3 ( X =26.30±14.8) in the inner harbour. Copepods, tintin-nids, decapods and chaetognaths formed dominant groups of total zooplankton ( > 90%) in the harbour waters throughout the year. Of the biochemical fractions of zooplankton, protein formed the major component, varied from 233.6 to 563 mg.g -1 (X=379.62±107), lipid varied from 61.2 to 181 mg.g -1 (X =103±32.7). Carbohydrate ranged from 65.5 to 127.4 mg.g -1 (X =85.78±16.92), organic carbon varied from 334.9 to 461.2 mg.g -1 (X=380.44±33.6) and calorific values varied from 2.2 to 5.4 (X =3.5±.94) k.cal.g -1 . Higher values of these constituents were observed during high saline premonsoon and postmonsoon periods when the population densities of copepods, tintinnids, decapods, chaetognaths were high. Significant positive correlations (P < 0.01) observed between calorific values, protein, lipid indicates to certain extent, that latter act as metabolic reserve of the zooplankton. Based on the results zooplankton do not have extensive lipid storage suggesting that protein in addition to the lipid may serve as metabolic reserve. Relatively higher calorific values were attributed to the dominance of copepods in the zooplankton population throughout the year.

Nutrients and phytoplankton in the Babadillimani Bight, northeastern Mediterranean coast of Turkey

Abstract: Phytoplankton taxa and abundance were determined and nutrients and chlorophyll a were measured in the Babadillimani Bight located in the northeastern Mediterranean coast of Turkey. Sampling was performed four times between the period of 1999 and 2000. The concentration of, PO 4 -P, NO 3 +NO 2 -N and [Si(OH) 4 ]-Si in surface water varied in the range of <0.01-0.22 μM, 0.37-1.23 μM and 0.52-2.02 μM, respectively. Surface water phytoplankton abundance reached the highest level (572.4 × 10 2 cells 1 -1 ) in March mainly due to the increase of a diatom, Skeletonema costatum. It reached the lowest level in August (3.36 × 10 2 cells 1 -1 ). Chlorophyll a concentrations ranged from 0.1 μg 1 -1 to 0.87 μg 1 -1 in surface water. Nutrient concentrations and phytoplankton biomass of the research area were found poorer than those of the many other coastal areas in the region and the other world oceans. Although the study was performed in a coastal area, the results reflect the oligotrophic nature of the eastern Mediterranean.

Maturation and spawning of four commercially important penaeid shrimps of Pakistan.

Abstract: The spawning seasons of four species of penaeid shrimp, Penaeus penicillatus (Alcock), P. merguiensis (de Man), Metapenaeus affinis (Milne Edwards) and Parapenaeopsis stylifera (Milne Edwards) from Pakistan’s inshore waters were studied on the basis of ovarian colour and ovarian histology. During maturation shrimp ovaries pass through a series of colour changes. Females with green ovaries (green yellow, green white, light green and dark green) were considered as spawning females while those with other than green ovaries (translucent, white, cream and yellow) were considered as nonspawning. The maturation stages of the ovaries recognized histologically in these shrimps are: undeveloped, developing, nearly-ripe, fully-ripe, resorbing and resorbing/developing. Presence of nearly-ripe or fully-ripe ovaries in these species throughout the year suggests that these shrimps have the potential for spawning throughout the year. However, P. penicillatus, P. merguiensis and M. affinis showed two spawning peaks, the first one in winter-spring (February-May) and second one in July, September and/or October. In P. stylifera the spawning was more frequent from November to February. The present study indicated that the spawning seasons based on the colouration of the ovaries and on ovarian histology are more or less similar. One of the most important aspects of the reproductive biology of penaeid shrimps is the study of the histological basis of ovarian maturity and the spawning seasons, which is required for the management of the stock as well as for aquaculture. Such studies have not been made in Pakistan waters. Some studies 1-5 have been conducted in Pakistan to determine the spawning seasons of penaeid shrimps. However, none of these were based on histological observations of ovaries. In other parts of the world, the ovarian development of several penaeid species has been described histologically 6 – 10 . It is a well-known biological observation that the ovaries of shrimps pass through a series of colour changes during their maturation process. Based on these colour changes 3-5 maturation stages have been recognized 11-13 . In the present investigation, the spawning season of the commercially important penaeid shrimps [viz., Penaeus penicillatus (Alcock), Penaeus merguiensis (De Man), Metapenaeus affinis (Milne Edwards) and Parapenaeopsis stylifera (Milne Edwards) (Arthropoda/Crustacea/Decapoda/ Penacidae)] was studied with the help of ovarian colour and ovarian histology.

Settlement pattern of ascidians in harbour waters of Mumbai, west coast of India

Abstract: The study was carried out in Mumbai (Bombay) harbour during 1995-96 by exposing perspex coupons at two study sites, namely South break waters and Tidal basin . Though the ascidian species, solitary or colonial, settle throughout the year, their prevalence however, varies considerably from month to month. As many as ten species of ascidians were recorded from the two sites. Out of these, seven species, namely Symplegma reptans, Symplegma brakenbielmi, Symplegma viride, Diplosoma macdonaldi, Botrylloides magnicoecum, Botrylloides chevalense and Ecteinascidia sp. are colonial ascidians and Styela bicolor, Ascidia indica and Ascidia sydneiensis are solitary forms. Of these, the species namely A. sydneiensis B. magnicoecum, B. chevalense, S. viride, D. macdonaldi and A. indica are reported for the first time from this region. Amongst these, S. reptans, B. magnicoecum and A. sydneiensis are of common occurrence. The species S. reptans and A. sydneiensis occurred throughout the year. During monsoon (June-September), the settlement of ascidians at cleaner south break waters is notably reduced, whereas, at tidal basin the colonies recorded were around 110/m 2 . At south break waters, during post-monsoon period, when water temperature reduced to 27°C and sea conditions are normal, the ascidians appeared in large number (max.1776/m 2 ). During pre-monsoon period, though the population density varied, the species composition remained high at both the sites. The non-monsoon months of October to May is the favourable period for ascidian settlement in Mumbai harbour.

Quantitative study of Co(II) complexation by synchronous fluorescence spectroscopy with Sundarban mangrove habitat humic substances

Abstract: Attempt has been made to isolate and characterize humic substances and their relative role for complexation of Co (II) in the mangrove sediment. Conditional stability constant (K c ) for Co (II) complexes with humic and fulvic acids were determined by studying quenching of fluorescence intensity of humic substances with Co (II) using synchronous fluorescence spectroscopy. Fulvic acid forms more stable complex than humic acid with K c of the order of 4.7×10 11 and 1.02×10 11 , respectively at pH 7, ionic strength of 0.1 and temperature of 25°C. Rigid frame work of fulvic acid having more electron donor groups as -OH, -NH 2 and less incorporation of -COOH than humic acid could be the reason for its formation of more stable complex with Co (II) than humic acid.

Biomass, horizontal zonation and vertical stratification of polychaete fauna in the littoral sediment of Cochin estuarine mangrove habitat, south west coast of India

Abstract: Biomass distribution, horizontal zonation, relative dominance and vertical distribution of polychaetes were studied Highest biomass was recorded in the mid tidal region in both study areas The monthly values varied from 443 to 12828 gm -2 at st 1 and 257 to 6731 gm -2 at st 2 Multiple regression analysis between biomass and environmental parameters indicate that they could not individually or in combination bring about the spatial and temporal variability in biomass distribution Moreover, at st 1 edaphic factors appear to be responsible for partial variation in biomass indicating comparatively high F ratio for variance analysis than station 2 ANOVA of species diversity indices values (P 70%) among polychaete fauna This similarity and affinity of fauna for a long period evidently indicate the habitat stability that is pertained to the existence of species diversity and abundance This is related to the prolonged food resource input and profound standing capacity in the littoral mangrove soil, which virtually render in building up a stable community structure of polychaetes As a result of this, selection of habitat by polychaetes, its survival and subsequent long-term biomass production were occurred The strong similarity of polychaete fauna between months and biomass productivity can be considered for deriving the productive characteristic of the mangrove habitat, and also for assessing demersal fishery potential

Imposex in rock whelks Thais and Ocenebra species (Mollusca, Neogastropoda, Muricidae) from Gujarat coast

Abstract: Imposex in Thais bufo, T. rudolphi, T. tissoti and Ocenebra bombayana was observed from Saurashtra coast of Gujarat. The maximum percentage of imposex out of total sample size (44.80 and 46.55%) were observed at Porbandar in T. bufo and T. rudolphi respectively while T. tissoti and O. bombayana at Mahuva showed 10.29 and 9.72% of imposex respectively. The percentage conversion of potential females to imposex was minimum at Diu and maximum at Porbandar. The number of ships operated from Porbandar and Diu directly correlated with severity of CPFII and percentage of imposex at these places. The results indicate that severity of imposex in T. rudolphi could be utilized as a bioindicator of TBT contamination in the marine environment. The Relative Penis Size Index(RPSI) ranged from 3.24 at Veraval to 16.50 at Porbandar in T. bufo while in T. rudolphi it ranged from 44.26 at Okha and 55.96 at Veraval. It was 21.19 and 14.26 for T. tissoti and O. bombayana respectively. The results indicate that RPSI may not be a foolproof indicator of severity of imposex in these organisms. Therefore a new index has been developed which is termed as Conversion of Potential Females to Imposex Index (CPFII) to calculate the potential females of a given area of a population. It seems the causative agents in seawater is neither toxic nor growth inhibitory at all the places of study but it interferes with the reproductive mechanisms and morphogenesis in these four species. The imposex in these organisms and its relation to TBT concentration in the marine environment is discussed.

Imposex in muricid gastropod Thais biserialis (Mollusca: Neogastropoda: Muricidae) from Tuticorin harbour, southeast coast of India

Abstract: Imposex has been reported in the muricid gastropod Thais biserialis from inside the Tuticorin port. The sex ratio departed from 1:1 and the males were dominant. The frequency of imposex in females was 35%. The Vas deferens sequence (VDS) index indicated the occurrence of initial imposex stages of la and 2a i.e. the development of penis and penis with closed duct. The Relative penis size (RPS) index values were less when compared to the reports elsewhere. The observation of imposex indicated the possible contamination of tributyltin (TBT), which could have leached out from antifouling paints of the ships using Tuticorin port.

Effect of ultraviolet-B radiation on biochemical composition of three Ulva species (Chlorophyta) from southeast coast of India

Abstract: The young plants of Ulva fasciata, U. reticulata and U. lactuca were subjected to UV-B (320-280 nm) radiation for 30, 60, 90, 120, 150 and 180 min. The changes in chlorophylls, carotenoids, protein, nitrate contents and reductase activities were studied. Compared to control, in UV exposed plants both pigments and protein concentrations were significantly decreased. The magnitude of such decrease was higher in Ulva lactuca than in other two species. In contrast to this in vitro nitrate reductase activity was more severely affected in Ulva reticulata. The experiments clearly showed that the UV (A & B)-B radiation has a strong inhibitory effects on biochemical properties in all three Ulva species. However, the rate of inhibition is dependent on the duration of exposure of plants to UV (A & B)-B radiation.