The results of an investigation carried out during October 2005 to September 2006 on hydrography composition and community structure of phytoplankton and zooplankton including chlorophyll 'a' (Chl-a) content and primary productivity (PP) at the Kaduviyar estuary (Southeast coast of India) are reported. Air and surface water temperatures (degrees C) varied from 23 to 29 and from 24 to 31 respectively while the light extinction coefficient values (LEC) ranged between 0.15 and 0.59. Salinity values (per thousand) varied from 4 to 34 and the pH ranged between 7.8 and 8.3. Variation in dissolved oxygen content was from 3.06 to 5.63 mg l(-1). The ranges of inorganic nutrients (microM) viz., nitrate, nitrite, phosphate, silicate and ammonia were: 0.36-12.65; 0.06-1.86; 0.06-4.57; 17.96-235.06 and 0.001-0.75 respectively. The ranges of Chlorophyll 'a' (mg m(-3)) and the primary productivity (mg Cm(-3) hr(-1)) values were: 3.4-12.8 and 55-119 respectively. Presently, 85 phytoplankton species representing different classes viz: Bacillariophyceae (58); Dinophyceae (16); Cyanophyceae (7); Chlorophyceae (3) and Chrysophyceae (1) were recorded. The phytoplankton density varied from 14,135 to 74,697 cells l(-1), with peak diversity (3.46 bits ind.(-1)) during premonsoon season. The maximum density was found during summer season coinciding with the stable hydrographical conditions. Totally 92 species of zooplankton besides 18 larvae were recorded and the copepods formed the dominant group. The occurrence of most of the zooplankton species showed a distinct seasonal pattern, which was closely associated with the species-specific environmental conditions. That way the environmental factors exert major influence on the species composition, abundance and diversity of zooplankton. The zooplankton density (org. l(-1)) ranged between 4342 and 14,002 and between 4867 and 15,816 at stations 1 and 2 respectively. Kaduviyar estuarine waters were very rich in zooplankton diversity (bits ind.(-1)) viz: 5.29 at Station 2 which was slightly higher than 5.27 at Station 1. Higher values of zooplankton density and species diversity were found during premonsoon and summer seasons and which showed positive correlation with salinity. The seasonal distribution and abundance of plankton are discussed in relation to hydrographical parameters.

Seasonal variations of plankton diversity in the Kaduviyar estuary, Nagapattinam, southeast coast of India

In total, 186 species of holoplankton and 23 different types of meroplankton were encountered during this study. Zooplankton community was dominated by copepods represented by 112 species, belonging to 4 orders and 26 families. Calanoida emerged as the most dominant order among the copepods being comprised of 68 species. It was followed by poicilostomatoids with 26 species, cyclopoids with 10 species and harpacticoida with 8 species. Paracalanus aculeatus emerged as the most dominant species during pre-monsoon season while, Acrocalanus longicornis was dominant in monsoon and A. gibber in the post-monsoon season. Other dominant copepods were Oithona sp., Miracia efferata, Acartia southwelli, Centropages tenuiremis, Paracalanus parvus, Acrocalanus gracilis and Acartia erythraea. Average zooplankton density ranged from 2387 org./10m 3 to 11659 org./10m 3 . Zooplankton volume ranged from 0.65 ml/10m 3 in monsoon to 1.51 ml/10m 3 in post- monsoon season. Despite high species abundance during premonsoon period, species diversity was maximum in monsoon. Species richness and dominance indices remained higher during post-monsoon whereas Pielou's evenness (J') was more in monsoon. Non-metric multidimensional scaling (MDS) ordinations based on Bray-Curtis similarities indicated that species composition was unequal during different months as there was no similarity above 40% level. (Keywords: Zooplankton, Copepod, Coastal water, Hydrography, Bay of Bengal)

/pdf/zooplankton-distribution-in-coastal-water-of-the-north-323tc0ooe2.pdf

Zooplankton distribution in coastal water of the North-Western Bay of Bengal, off Rushikulya estuary, east coast of India

Impact of multispecies diatom bloom on plankton community structure in Sundarban mangrove wetland, India.

The impact of long-term environmental change on zooplankton along the southwestern coast of India

Ocean climate drivers and phytoplankton life strategies interact in a complex dynamic to produce harmful algal blooms (HABs). This study aims to integrate historical biological data collected during “red tide” events along the Ecuadorian coast between 1997 and 2017 in relation to five ocean variables derived from satellite remote sensing data to explain the seasonal drivers of coastal processes associated with HABs dynamics. Seasonality of the occurrence of HABs was assessed in relation to oceanographic variables by applying multiple correspondence analysis (MCA) to the Ecuadorian central coast (Zone 1) and at the outer and inner Gulf of Guayaquil (Zone 2). Sixty-seven HABs events were registered between 1997 and 2017. From a total of 40 species of phytoplankton identified, 28 were identified as non-toxic and the remaining 12 are well known to produce toxins. Dinoflagellates were the taxonomic group most highly associated with potential HABs events along the entire Ecuadorian coast. HABs appear to be constrained by the Humboldt coastal upwelling, high precipitation, and associated coastal runoff, with higher biomass abundance in the Gulf of Guayaquil than in the central coast. Results from the MCA reveal that in the central Ecuadorian coast (oligotrophic system), toxic HABs occurred with low abundance of dinoflagellates, while in the Gulf of Guayaquil (eutrophic system), toxic HABs corresponded to a high abundance of dinoflagellates. In both cases, high values were found for sea surface temperature, precipitation, and irradiance—characteristic of wet seasons or El Nino years. Non-toxic HABs occurred with a high abundance of dinoflagellates, ciliates, and centric diatoms, corresponding to colder waters and low levels of precipitation and irradiance. These findings confirm that dinoflagellates display several strategies that enhance their productive capacity when ocean conditions are warmer, allowing them to produce toxins at high or at low concentrations. Considering that the Gulf of Guayaquil is essential to tourism, the shrimp industry, fisheries, and international shipping, these findings strongly suggest the need to establish an ecosystem health research program to monitor HABs and the development of a preventive policy for tourism and public health in Ecuador.

/pdf/oceanography-of-harmful-algal-blooms-on-the-ecuadorian-coast-2bi7hfilf7.pdf

Oceanography of Harmful Algal Blooms on the Ecuadorian Coast (1997–2017): Integrating Remote Sensing and Biological Data

Underwater surveys were conducted in the shallow coastal waters extending from Enayam to Kollam, southern India, covering six study locations viz., Enayam, Adimalathura,Vizhinjam, Varkala, Odayam and Paravoor to record the diversity of sponges. A total of 24 species of sponges were identified during the study which belonged to 20 genera, 14 families and 6 orders. Maximum species diversity was recorded at Enayam (11 species), followed by an equal number of species at Vizhinjam and Adimalathura (10 species). Five species of sponges were recorded at Odayam while three species were recorded at Varkala and only one at Paravur. Shannon diversity was high at Enayam, Vizhinjam and Adimalathura and the dominance plot also showed rich diversity of sponges in these three stations.The cluster results using Bray Curtis similarity Index indicated two clusters: stations Enayam, Vizhinjam and Adimalathura showed one cluster indicating similarity of species in these stations, while the stations Varkala, Odayam and Paravoor showed another cluster. The present study has indicated that the stations Enayam, Vizhinjam and Adimalathura are rich in diversity and abundance of sponges, compared to Varkala, Odayam and Paravoor.

/pdf/diversity-and-distribution-of-shallow-water-sponges-porifera-cztn1nuiw5.pdf

Diversity and distribution of shallow water sponges (Porifera) in the coastal waters from Enayam to Kollam, south-west coast of India

The present article embodies a critical appraisal of the blooms observed at Karwar, Mangalore, Cochin, Vizhinjam, Tuticorin and Madras from 1982 to 1987. Noctiluca miliaris, Coscinodiscus sp. and Fragilaria oceanica are the three common species which appear in blooms regularly. There are some other phytoplankters also which bloom occasionally at restricted areas. These include species of Ceratium, Chaetoceros, Rhizosolenia, Biddulphia, Skeletonema, Thalassionema, Thalassiosira subtilis, Thalassiothrix and Trichodesmium.

Phytoplankton Blooms along the Indian Coasts-some highlights

The quantity of gorgonids exported from India since then showed a downward trend, but the price/kg was on a steady increase. For 1,008 kg exported during 1983-'84 the total revenue realised was Rs. 1.04 lakhs, averaging Rs. 103.65 per kg. For these aesthetic reasons these animals have been collected all over the world, and from India too they have been exported under the head 'curio' for a long period. But the demand for this commodity was not at all specific and the revenue realised under this head was also not very attractive. The total quantity of gorgonids exported from India during 1975-'84 was estimated at 36.4 tonnes valued at Rs. 9.9 lakhs. At present 22 species of gorgonids referable to seven families and 15 genera are exported from India under four trade names or 'types' such as 'Black', 'Red', 'Monkey tail' and 'Flower'. The above commercial classification is based on colour. It is advisable to fix a minimum size for each species at which their exploitation could be commenced. In the event of extending the fishing activity to any of the virgin areas indicated in the section entitled 'Areas where fishing could be intensified', care should be taken to earmark some selected areas as 'gorgonid reserves.

Gorgonid resources of India

The hexactinellid sponge described in this paper, Semperella megaloxea sp. nov. was collected from the eastern side of NorthAndaman waters off Diglipur at 13o 06’ N lat. and 93o 11’ E long. during one of the FORV Sagar Sampada expeditions.Critical examination of the specimen indicated that it belonged to the Class Hexactinellida, Sub-class Amphidiscophora andOrder Amphidiscosida. Although diactin spicules are present, the presence of large number of pentactin spicules indicatesthat it belongs to the Family Pheronematidae. The columnar body with atrial surface divided into several areas separated bydermal areas indicates that the specimen belongs to the genus Semperella. The morphology of the whole sponge specimen,the presence of very long diactin spicules of oscular tuft and the pentactins with very long rays do not match well with anyof the already described species of the genus Semperella Gray.

/pdf/semperella-megaloxea-sp-nov-family-pheronematidae-a-3h7hbs08rp.pdf

Semperella megaloxea sp. nov. (Family: Pheronematidae): A newhexactinellid sponge from Andaman waters, India

The discovery of prostaglandin s in gorgonids and their clinical possibilities initiated a general interest in this group as an easily available source of several 'wonder drugs'. The exploitation of gorgonids on a commercial basis from the Indian Seas since 1975 may be said to be a part of this world-wide 'hunt' for raw materials. These organisms are now being exported to several countries at an average rate of 3.6 tonnes per year under rough commercial grouping of 'black', 'red', 'monkey tail' and 'flower' types. During the present survey specimens were examined both from the fishing centres and export samples. This study indicated that 22 species of gorgonids are being exploited from the Indian Seas at present and these are referable to 7 families and 15 genera. Among the families, the Paramuriceidae Bayer is well re­ presented in the commercial landings with 9 widely distributed species under 5 genera. This is followed by Ellisellidae Gray with 7 species under 5 genera. Species such as Echinomuricea indica Thomson and Simp­ son, Heterogorgia flabellum (Pallas), Gorgonella umbraculum (Ell. and Sol.), Leptogorgia australiensis Ridley and Juncella jUncea (Pallas), form the mainstay of the export in the order of abundance. Detailed descriptions of all species, their classification, distribution, size attained, etc. are presented in this paper with sketches of spicular complements to facilitate easy identification.

/pdf/a-systematic-appraisal-of-the-commercially-important-1ga17dyel7.pdf

A systematic appraisal of the commercially important gorgonids of the Indian seas

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