S. Bijoy Nandan

Lindane toxicity: Histopathological, behavioural and biochemical changes in Etroplus maculatus (Bloch, 1795)

The effects of sub-lethal concentrations of lindane on behavioral, hematological and histological parameters in Etroplus maculatus were investigated. The LC₅₀ value of lindane for E. maculatus was estimated using the Probit method and was found to be 0.028 mg/L. The red blood cell count (RBC) and the hemoglobin (Hb), hematocrit (Ht), mean corpuscular hemoglobin (MCH), mean corpuscular volume (MCV) and mean corpuscular hemoglobin concentration (MCHC) were significantly reduced (p > 0.0001) in fish exposed to the toxicant concentrations compared to the control groups. However, the white blood cell count (WBC) was observed to be significantly higher (p < 0.0001). Observations of the tissues showed that lindane had profound destructive effects on the gills, liver and kidney of the fish. The gills showed proliferation of the lamellar epithelium and lamellar fusion, the liver showed necrosis and the kidneys had constriction of the tubular lumen. The frequency of observed behaviors had the same levels of significance throughout the period of study. There was a reduction in the frequency of occurrence between test concentrations, but remained significantly higher than the control. The study shows that lindane is harmful to E. maculatus at sub-lethal concentrations and that the application of this pesticide close to bodies of water is a dangerous threat to aquatic life.

Retting Of Coconut Husk - A Unique Case Of Water Pollution On The South West Coast Of India

The extensive backwaters of Kerala are the sites for a flourishing cottage industry ‐ the coir industry. This enterprise almost exclusively located along the 590 km coastal belt of Kerala, provides direct employment to over half a million people in the state and produces nearly 90% of the total coir goods in the world. The shallow bays and lagoons of the 30 backwater systems of the state are traditional areas for the retting of coconut husk for the production of the coir fibre. The paper examines the environmental status of the retting grounds in Kerala, in relation to the biotic communities. The study revealed that retting activity has caused large scale organic pollution along with the mass destruction of the flora and fauna, converting sizeable sections of the backwaters into virtual cesspools of foul smelling stagnant waters. High values of hydrogen sulphide, ammonia, BOD5 associated with anoxic conditions and low community diversity of plankton, benthic fauna, fish, shell fish, wood boring and foulin...

Benthic polychaetes in the anoxic sulphide biomes of the retting zones in the Kadinamkulam Kayal

Retting is the basic process serving as the backbone of the Coir industry in Kerala. The shallow fringes of Kayals (estuaries) and channels drawn from them are the traditional sites for the retting of coconut husk. Retting is brought about by the pectinolytic activity of micro‐organisms especially bacteria, fungi and yeasts degrading the fibre binding materials of the husk and liberating large quantities of organic matter and chemicals into the environment, including pectin, pentosan, tannins and polyphenols. Retting of coconut husk has thus led to anoxic conditions along with the increase in hydrogen sulphide and BOD5 with a sharp depletion in the biotic communities. This paper presents the species composition, occurrence, abundance and diversity of the benthic polychaete population in relation to sulphide pollution.

Pollution indicators of coconut husk retting areas in the kayals of Kerala

The coast of Kerala is dotted with 31 kayals (estuaries) lying roughly parallel to the Lakshadweep sea and separated from it by a narrow strip of land 0.4 to 12 km wide. The abundant availability of coconut husk and the generally shallow nature of the kayals have led to the emergence of the coir industry as a massive cottage industry in the state. Fresh coconut husks, steeped in the shallow regions of kayals are allowed to remain soaked in water for periods ranging from 4–12 months. Retting is brought about by the pectinolytic activity of microorganisms liberating large amounts of organic matter and chemicals into the environment. The retting zones in estuaries are thus exposed to prolonged periods of anoxic condition resulting from a total oxygen depletion and remarkably high concentrations of hydrogen sulphide, thus causing extensive damage to the living, aquatic resources in the region. The paper deals with indicator organisms specific to pollution from retting of coconut husk in the kayals of Kerala.

New species of Victoriopisa Karaman & Barnard, 1979 (Crustacea: Amphipoda: Eriopisidae) from Vembanad backwaters, Southwest coast of India

The new species is the third of genus Victoriopisa from Indian waters.The species is described from the Valanthakad mangrove area of Vembanad backwater. Victoriopisa cusatensis sp. nov differs from other species of Victoriopisa by presenting: (1) a characteristic projection at dorsolateral margin of peduncle article 2 of antenna 1in male while smooth in female; (2) broad, triangular lateral cephalic lobe; (3) posteroventral tooth in epimeral plates; (4) presence of lateral and subapical spines in telson (5) smooth palm of gnathopod 2 without any excavations.

Reassessing the species status of Pseudodiaptomus malayalus Wellershaus, 1969 and P. binghami Sewell, 1912 (Calanoida: Pseudodiaptomidae) from India based on morphology and mitochondrial cytochrome oxidase I gene sequences

Abstract Pseudodiaptomus binghami Sewell, 1912 was first described from the Rangoon River (now Yangon River) estuary, Myanmar. Pseudodiaptomus malayalus Wellershaus, 1969 previously known as P. binghami malayalus, is a typical brackish-water calanoid copepod from Cochin Estuary, Kerala. Morphological examination of P. malayalus and P. binghami collected from Cochin Estuary and the Nambur canal in Andhra Pradesh revealed crucial differences between the two congeners. Female specimens of P. malayalus exhibited marked differences from those described by Wellershaus. They are (1) the number of terminal spines on P5, (2) ornamentation of GS, (3) ornamentation of Ur1–4, (4) length ratio of the Ur and CR segments and (5) length:width ratio of the CR setae. Furthermore, significant and discrete morphological differences were observed between the two Indian species in their P5 and urosome. But the male specimens of P. malayalus did not show any major differences from the original description. In addition, distance matrix data revealed 22% interspecific divergence values which in turn confirmed the status of P. malayalus and P. binghami as two distinct species.

Toxicity effects of zinc on two marine diatoms, under varying macronutrient environment

Diatoms constitute one of the fundaments in the trophic food chains and are responsible for much of the bioaccumulation of heavy metals, in particular zinc, throughout the web of food chains. Chaetoceros calcitrans and Thalassiosira weissflogii are widely present as a dominant marine diatom in estuarine and coastal waters. The zinc uptake, its fractionation in subcellular structures and macromolecular compartments in two marine diatoms, C. calcitrans and T. weissflogii and trophic transfer under different macronutrient concentrations were investigated. The study reveals a significant interaction between macronutrients and metal uptake by the two diatom species. Increased cellular accumulation of zinc and N, P-limited condition were found to affect N, P and Si assimilation by diatoms negatively. Conversely, nitrogen (N) limitation inhibited the intracellular uptake of zinc. However, at higher concentration of zinc, the difference in zinc uptake between nutrient enriched condition (+NP) and nutrient limited (N or P) condition become smaller, indicating that the zinc uptake by diatoms is less dependent on N containing protein ligands at high Zn concentration. Nitrogen concentration in the medium was also found to affect the relative distribution of zinc in subcellular structures and macromolecular components. However, major portion of zinc was distributed in soluble substance and in the protein of the algal cells. The N limited condition facilitates the accumulation of zinc in cell organelles (insoluble substance) leading to increased toxicity. Trophic transfer of zinc was also measured by calculating percentage of metal retained in mussel, Perna viridis over the experiment period. Regardless of the algal species, the percentage of accumulation of zinc was found to be high in mussels fed with algal cells acclimated to nutrient enriched condition (31 and 38%). Our study therefore suggests that N enrichment may lead to an increase in Zn uptake and transfer in marine plankton.

Cuspidaria cochinensis Preston, 1916 transferred to the Corbulidae (Mollusca, Bivalvia) and assigned to the genus Cuneocorbula

An examination of a syntype of Cuspidaria cochinensis Preston, 1916, focusing on the characters of the hinge, supports the transfer of this species to the family Corbulidae. Recently collected material from the Cochin Backwater is used to describe the shell and anatomy of the adult form. The ctenidia are composed of two demibranchs, both flat and homorhabdic, this further confirming that this species is eulamellibranch and not septibranch. The most appropriate generic placing of this species is in Cuneocorbula; thus, it is the first recorded extant species of the genus.

Morphological and molecular identification of marine copepod Dioithona rigida Giesbrecht, 1896 (Crustacea:Cyclopoida) based on mitochondrial COI gene sequences, from Lakshadweep sea, India

Abstract Morphological identification of the marine cyclopoid copepod Dioithona rigida in combination with sequencing a 645 bp fragment of mitochondrial cytochrome oxidase c subunit I (mtCOI) gene, collected from offshore waters of Kavarathi Island, Lakshadweep Sea, is presented in this study. Kiefer in 1935 classified Dioithona as a separate genus from Oithona. The main distinguishing characters observed in the collected samples, such as the presence of well-developed P5 with 2 setae, 5 segmented urosome, 12 segmented antennule, compact dagger-like setae on the inner margin of proximal segment of exopod ramus in P1–P4 and engorged portion of P1-bearing a spine, confirmed their morphology to D. rigida. A comparison of setal formulae of the exopod and endopod of D. rigida with those recorded previously by various authors are also presented here. Maximum likelihood Tree analysis exhibited the clustering of D. rigida sequences into a single clade (accession numbers KP972540.1-KR528588.1), which in contrast was 37–42% divergent from other Oithona species. Further intra-specific divergence values of 0–2% also confirmed the genetic identity of D. rigida species. Paracyclopina nana was selected as an out group displayed a diverged array. The present results distinctly differentiated D. rigida from other Oithona species.

Species Composition and Distribution of Sponges (Phylum: Porifera) in the Seagrass Ecosystem of Minicoy Atoll, Lakshadweep, India

Studies on diversity of fauna associated with seagrass ecosystem of Minicoy Atoll, Lakshadweep were conducted for 2 years. Sponges were the important associated macrofauna in the seagrass meadow as attached to the leaves, stem and rhizome of the seagrass, or sometimes found attached to hard substratum in the meadow. As part of this study, species composition and abundance of sponges were analyzed from four stations in the seagrass meadow. Total of 22 species of sponges were recorded which belong to 21 genera, 19 families, 10 orders, and 2 classes. The following species were recorded from the four study stations and these constituted 10 % of the total faunal population of seagrass meadow namely, Clathrina sp., Scypha ciliata, Dysidea fragilis, Fasciospongia cavernosa, Ircinia compana, Aurora globostellata, Cliona sp., Spirastrella inconstans, Suberites sp., Tethya diploderma, Xenospongia sp., Halichondria sp., Haliclona pigmentifera, Haliclona tenuiramosa, Callispongia sp., Gelliodes cellaria, Sigmadocia fibulata, Hyatella cribriformis, Spongia officianalis, Echinodictyum longistylum, Thalysias reinwardti and Psammaplysilla purpurea. In the Station I, the abundance of sponges was significantly correlated with seagrass shoot density (P < 0.01, r = 0.626). Highest mean seasonal density of 3.13 ± 4.63 individual m−2 was recorded during monsoon and spatially, 3.33 ± 4.46 individual m−2 in the Station III. Studies on the community structure of macro-invertebrate fauna in the seagrass meadow of Minicoy Atoll were less. This study highlights the species composition of sponges in the seagrass meadow of Minicoy Atoll and it will be useful in future for the assessment of changes in ecosystem and conservation management.