The September 2004 stench off the southern Malabar coast - A consequence of holococcolithophore bloom

During the third week of September 2004, particularly on 16th and 17th, an unusual and strong stench was reported from the coast at Kollam and Vizhinjam in Kerala (India). Local dailies reported that over 200 children, mostly below 15 years, complained of nausea, chest pain and short periods of breathlessness because of the stench. Many were hospitalized, but were discharged within a couple of hours. A press report stated that the stench was due to dead fish scattered on the beaches and in the water. The report linked the fish death to oxygen depletion and choking of fish gills. Both were reported to be possibly due to proliferation and eventual putrefaction of a fish-toxic alga Cochlodinium polykreikoides. Information was put up on the web that the bloom was caused by Karenia brevis, a toxic dinoflagellate. It was reported that the stench could be felt up to 5 km inland from the coast. On 20 September 2004, the Government of Kerala requested the National Institute of Oceanography (NIO), Goa to determine the cause of the phenomenon. In response, a team from NIO collected near-shore samples of water on 23 and 26 September off Vizhinjam, Shanghumugham and Kollam. During 3-7 October 2004, RV Sagar Sukti, a coastal research vessel of NIO, was used to collect samples in the waters offshore of Vizhinjam, Veli, Kollam in the depth zones of 20-50 m. The water samples collected on 23 and 26 September from the near-shore spots were analysed for various chemical (dissolved oxygen, hydrogen sulphide, nutrients, and salinity) and biological (microbiological, phytoplankton counting and identification) variables. Data from sea-level records at Cochin Port were also examined to learn about the possible evolution of physical conditions before and after the episode described above. In this preliminary report inferences based on analysis of the data is presented

Marine Drugs from Sponge-Microbe Association—A Review

The subject of this review is the biodiversity of marine sponges and associated microbes which have been reported to produce therapeutically important compounds, along with the contextual information on their geographic distribution. Class Demospongiae and the orders Halichondrida, Poecilosclerida and Dictyoceratida are the richest sources of these compounds. Among the microbial associates, members of the bacterial phylum Actinobacteria and fungal division Ascomycota have been identified to be the dominant producers of therapeutics. Though the number of bacterial associates outnumber the fungal associates, the documented potential of fungi to produce clinically active compounds is currently more important than that of bacteria. Interestingly, production of a few identical compounds by entirely different host-microbial associations has been detected in both terrestrial and marine environments. In the Demospongiae, microbial association is highly specific and so to the production of compounds. Besides, persistent production of bioactive compounds has also been encountered in highly specific host-symbiont associations. Though spatial and temporal variations are known to have a marked effect on the quality and quantity of bioactive compounds, only a few studies have covered these dimensions. The need to augment production of these compounds through tissue culture and mariculture has also been stressed. The reviewed database of these compounds is available at www.niobioinformatics.in/drug.php

Sulfate Reducing Bacteria from Mangrove Swamps of Goa, Central West Coast of India

153-157Levels of lactate and acetate oxidising sulfate reducing bacteria in sediment samples of mangrove swamps were in the order of 103 g-1 dry sediment and the counts decreased with depth. Lactate utilisers were generally higher in number than acetate utilizers. Of the 20 strains studied from lactate based medium and 21 from acetate based medium 20 and 47.6U+0025 respectively were spore formers. The strains were all mesophilic and euryhaline (0-40 x 10-3). About 60U+0025 of the former grew on acetate while 71.4U+0025 of the latter grew strictly on format. The strains were all Gram negative and cytochrome-C positive

Occurrence & distribution of <i>Vibrio parahaemolyticus</i> (Sakazaki <i>et al.</i>) & related organisms in the Laccadive Sea

96-98Distribution of V. parahaemolyticus and related organisms in the water column up to 200 m deep showed a fluctuating trend. Typical V. parahaemolyticus was not isolated from water samples collected at 200 m. However, zooplankton samples from all stations yielded V. parahaemolyticus. This study showed that V. parahaemolyticus occurs in offshore waters but in low numbers

Denitrification activity is closely linked to the total ambient Fe concentration in mangrove sediments of Goa, India

International audienceDenitrification activity (DNT) and associated environmental parameters were examined in two mangrove ecosystems of Goa, India e the relatively unimpacted Tuvem and the anthropogenically-influenced Divar. Sampling was carried out at every 2 cm interval within the 0-10 cm depth range to determine (1) seasonal (pre-monsoon, monsoon and post-monsoon) down-core variation in DNT (2) assess the environmental factors influencing the DNT and (3) to build predictive models for benthic DNT. Denitrification generally decreased with depth and showed marked seasonal variation at both the locations. Denitrification peaked during the pre-monsoon occurring at a rate of up to 21.00- 12.84 nmol N2O /g h within 0-4 cm at both the locations. Further, DNT at pre-monsoon was significantly influenced by Fe content at Tuvem and Divar suggesting Fe-mediated nitrate respiration. The influence of other limiting substrates such as NO3 and NO2 was most important during the monsoon and post-monsoon especially at Divar. The multiple regression models developed could predict 67-98% of the observed variability inDNT through the seasons. About 6-9 environmental variables were required to relatively well-predict DNT in these sediments with the complexity governing DNT decreasing from pre-monsoon to postmonsoon. Our results reveal that seasonal dynamics of DNT in tropical mangrove sediments are closely linked to the total Fe at the prevailing ambient concentration in both the system

Microbial activity promotes the enrichment of cobalt over nickel on hydrogenetic ferromanganese crusts

<p>The different mineral phases of the ferromanganese (Fe–Mn) crusts stem from the interaction of biotic and abiotic components. It is therefore vital to study the activity of these components to decipher their contribution to the enrichment/depletion of metals in the crust. Thus, the present study examined sorption and release of Co and Ni by Fe-Mn crusts with associated microbial communities in the presence and absence of the metabolic poison sodium azide (15 mM). The study was conducted in the presence (G⁺) and absence (G⁻) of added glucose (0.1%) at temperatures of 4 ± 1°C and 28 ± 2°C. Results showed that the microbial community had maximal sorption of Co of 66.12 µg g⁻¹ at 4 ± 1°C in the absence of added glucose and 479.75 µg g⁻¹ at 28 ± 2°C in the presence of added glucose. Maximum sorption of Ni in the absence of added glucose was 1.89 µg g⁻¹ at 4 ± 1°C and release of Ni was 51.28 µg g⁻¹ in the presence of added glucose. Under abiotic conditions with 15 mM sodium azide as a metabolic inhibitor, significant amounts of Co and Ni were released in the G⁺ medium. Total cell counts on the Fe-Mn crust in the presence of added glucose increased by an order of magnitude from 10⁶ to 10⁷ cells g⁻¹ and in the absence of added glucose remained within the order of 10⁶ cells g⁻¹ irrespective of temperature of incubation. Microscopic observation of the samples from biotic incubations showed numerous bacterial cells, exopolysaccharides, and structures resembling secondary minerals formed by bacteria. The results indicate that bacteria promote the enrichment of Co and Ni on the hydrogenetic Fe-Mn crusts by sorption processes and release of Ni by reductive dissolution of the oxides. The higher enrichment of Co than Ni is attributed to the way in which microbes interact with the metals.</p

Denitrification activity in mangrove sediments varies with associated vegetation

International audienceTo test the hypothesis that mangrove vegetation associated sediment characteristics could influence an ecologically important function such as denitrification, a study was carried out at the Divar mangrove ecosystem in Goa, India. The composition of intertidal mangroves was assessed based on which the down-core (0-10 cm) variation in environmental variables and denitrification activity (DNT) associated with dominant vegetation types was examined. Our observations revealed a distinct zonation pattern of mangroves with the dominance of Rhizophora mucronata (RM) in the lower intertidal zone followed by Avicennia marina (AM) in the mid region. Acanthus ilicifolius (AI) was restricted to the upper intertidal zone (UIZ) which was characterized by relatively lower sediment temperatures, higher porewater salinity and intense reducing conditions. A zonation pattern in occurrence of DNT was also observed. Denitrification activity generally decreased with depth and increased in intensity from the seaward to the landward side. Maximum DNT of 4.06 +/- 0.44 nmol N2O g(-1) h(-1) was recorded in the surficial AI sediments followed by AM and RM sediments. Surface plant litter content also increased from the lower to UIZ. A negative relationship of NH4+ and total organic carbon content (n=15, r=-0.388, p<0.05) in AI sediments was observed. This suggested that re-mineralization of accumulated organic matter (up to 3.07 + 0.58% at 0-2 cm) enhanced NH4+ availability in the porewater which in turn could support nitrification-denitrification. Thus, degradation of vegetation-derived organic matter was important in sustaining nutrients mainly towards the landward side proving our hypothesis that vegetation could have an influence on DNT, albeit indirectly. (C) 2016 Published by Elsevier B.V