K. K. Satpathy

A comparison of sediment quality guidelines for toxicity assessment in the Sunderban wetlands (Bay of Bengal, India).

The aim of this paper was to obtain the first screening ecotoxicological risk evaluation in the Sunderban wetlands, the largest prograding delta in the estuarine phase of the River Ganges. The characterization of exposure was conducted by means of an extensive survey of several persistent organic pollutants (PAHs, PCBs, DDTs, PBDEs, HCHs, HCB) measured in seven core sediments from the Sunderban wetlands, obtaining a dataset with more than 2200 analyses. The pollutant effects were assessed by the use of three different sediment quality guidelines (SQGs) previously developed in the literature to evaluate toxicity induced in sediment-dwelling organisms. The three different approaches chosen for risk assessment of the Sunderban were the consensus SQGs obtained by TEC (threshold effect concentration), PEC (probable effect concentration) and EEC (extreme effect concentration), the threshold/probable effect level (TEL/PEL) approach and, finally, the ERL-ERM guidelines, including the m-ERM-Q (mean ERM quotient). The evaluation of the toxicity induced by a mixture of the target pollutants indicated the importance of gamma-HCH contamination in the Sunderban sediments despite the very low concentrations measured in core sediments. A different sensitivity for toxicity assessment due to quality guidelines was obtained, as the consensus SQGs based on TEC were less conservative and protective than the TEL and ERL approaches, while the use of m-ERM-Q seems to be the most powerful tool to predict the toxicity related to a contaminant mixture.

Commonness and rarity in the marine biosphere

Significance Tests of biodiversity theory have been controversial partly because alternative formulations of the same theory seemingly yield different conclusions. This has been a particular challenge for neutral theory, which has dominated tests of biodiversity theory over the last decade. Neutral theory attributes differences in species abundances to chance variation in individuals’ fates, rather than differences in species traits. By identifying common features of different neutral models, we conduct a uniquely robust test of neutral theory across a global dataset of marine assemblages. Consistently, abundances vary more among species than neutral theory predicts, challenging the hypothesis that community dynamics are approximately neutral, and implicating species differences as a key driver of community structure in nature. Explaining patterns of commonness and rarity is fundamental for understanding and managing biodiversity. Consequently, a key test of biodiversity theory has been how well ecological models reproduce empirical distributions of species abundances. However, ecological models with very different assumptions can predict similar species abundance distributions, whereas models with similar assumptions may generate very different predictions. This complicates inferring processes driving community structure from model fits to data. Here, we use an approximation that captures common features of “neutral” biodiversity models—which assume ecological equivalence of species—to test whether neutrality is consistent with patterns of commonness and rarity in the marine biosphere. We do this by analyzing 1,185 species abundance distributions from 14 marine ecosystems ranging from intertidal habitats to abyssal depths, and from the tropics to polar regions. Neutrality performs substantially worse than a classical nonneutral alternative: empirical data consistently show greater heterogeneity of species abundances than expected under neutrality. Poor performance of neutral theory is driven by its consistent inability to capture the dominance of the communities’ most-abundant species. Previous tests showing poor performance of a neutral model for a particular system often have been followed by controversy about whether an alternative formulation of neutral theory could explain the data after all. However, our approach focuses on common features of neutral models, revealing discrepancies with a broad range of empirical abundance distributions. These findings highlight the need for biodiversity theory in which ecological differences among species, such as niche differences and demographic trade-offs, play a central role.

Biofouling and its Control in Seawater Cooled Power Plant Cooling Water System - A Review

Biofouling may be defined as the attachment and subsequent growth of a community of usually visible plants and animals on manmade structures exposed to seawater environment. Man has long been aware of this problem. In the fourth century B.C., Aristotle is reported to have stated that small “fish” (barnacles) were able to slow down ships. Fouling of ship hulls, navigational buoys, underwater equipment, seawater piping systems, industrial or municipal intakes, beach well structures, oil rigs and allied structures has often been reported. In the past few decades, the list of affected structures has expanded. Now, reports are common regarding the biofouling that affects Ocean Thermal Energy Conversion (OTEC) plants, offshore platforms, moored oceanographic instruments and nuclear and other submarines. The impact of biofouling on sea front structures is staggering. Ships show a 10% higher fuel consumption caused by increased drag and frictional resistance resulting from hull and propeller fouling. Water lines lose their carrying capacity and speed of flow owing to biofouling growth along pipe systems. The heat exchanger performance declines due to attachment of biofoulants. Many marine organisms themselves face the constant problem of being colonized and overgrown by fouling organisms. Immobile plants and animals are generally exposed to biofouling and consequent loss of species and community assemblages. Biofouling also promotes corrosion of materials. The money and material needed for fouling protection measures are indeed exorbitant. It is estimated that the marine industry incurs an expenditure of 10 billion sterling pounds a year to combat the situations arising from biofouling worldwide (Satpathy, 1990). A lot of research effort has been devoted to understand the fundamental ecology and biology of fouling environments, organisms and communities in diverse settings. The huge requirement of cooling water as well as accrescent demand on the freshwater has led to the natural choice for locating power plants in the coastal sites where water is available in copious amount at relatively cheap rate. For example, a 500 MW (e) nuclear power plant uses about 30 m3sec-1 of cooling water for extracting heat from the condenser 11

Congener profiles of polychlorinated biphenyls in core sediments of Sunderban mangrove wetland (N.E. India) and their ecotoxicological significance

The paper presents the first comprehensive survey of congener profiles of polychlorinated biphenyls (PCBs) in core sediment samples (<63 μm particle size) covering seven sites in Sunderban mangrove Wetland, north-eastern part of the Bay of Bengal. Results pointed out a non-homogenous contamination of the wetland with Σ23PCB values ranging from 0.5 to 26.9 ng g-1 dry weight, reflecting very low to moderate contamination closely in conformity to other Asian coastal environment. The general decreasing order of the dominant congeners to the total load was: CB138 > 153 > 149 > 101, indicating the predominance of hexa-chlorinated congeners. The spatial distribution revealed significant differences in concentration related to local urbanization with industrial and land-based sources. No uniform temporal trend on PCB levels was recorded probably due to particular hydrological characteristics of the wetland and/or non-homogenous inputs from point sources. Strong positive correlations between the seven dominant congeners suggest their common sources and similar environmental behaviors. These results were also used for a risk assessment evaluation in the Sunderban wetland, showing that the present PCB levels were exceeding in few cases the lower limit of sediment quality guidelines of Environmental Protection Agency and Canadian Council of Ministers of the Environment.

Geochemical Speciation and Risk Assessment of Heavy Metals in Soils and Sediments

Heavy metal pollution is a serious and widely environmental problem due to the persistent and non-biodegradable properties of these contaminants. Sediments serve as the ultimate sink of heavy metals in the marine environment and they play an important role in the transport and storage of potentially hazardous metals. They are introduced into the aquatic system as a result of weathering of soil and rocks, from volcanic eruptions and from a variety of human activities involving mining, dredging, processing and use of metals and/or substances containing metal contaminants. Heavy metals entering natural water become part of the watersediment system and their distribution processes are controlled by a dynamic set of physico‐ chemical interactions and equilibria. The properties of metals in soils and sediments depend on the physiochemical form in which they occur [1]. Heavy metals are distributed throughout soil and sediment components and associated with them in various ways, including adsorp‐ tion, ion exchange, precipitation and complexation and so on [2]. Changes in environmental conditions, such as temperature, pH, redox potential and organic ligand concentrations, can cause metals to be released from solid to liquid phase and sometimes cause contamination of surrounding waters in aquatic systems [3]. They are not permanently fixed by soil or sediment. Therefore, it cannot provide sufficient information about mobility, bioavailability and toxicity of metals if their total contents are studied alone.

Energy dispersive X-ray fluorescence analysis of ancient potteries from Vellore District Tamilnadu, India with statistical approach

Abstract In the present study concentration of trace elements in ancient potteries collected in Vellore Dist of Tamilnadu, India, was determined using ED-XRF technique. The analysed shreds are belong to the 18th century. Fourteen elements have been determined in 56 pottery fragments. These elemental concentrations were processed using multivariate statistical methods, principal component analysis and cluster analyses to determine similarities and correlation between the various samples. Chemical composition of examined shreds revealed the type of clay (Calcareous/Non-Calcareous). The statistical results revealed patterns of trade between these communities. The 56 shards had been classified into three major groups based on variations in composition.

Elemental distribution and trace metal contamination in the surface sediment of south east coast of India

Spatial distribution and potential ecological risk of trace metals in the surface sediment of south east coast of India covering eight different ecosystems was studied. The concentration of major elements viz. Ca, Mg, K, Ti and trace metals viz. Cr, Mn, Co, Al, Fe, Ni, Cu, Zn, Cd and Pb were analysed by energy dispersive X-ray fluorescence technique. Contamination factor, geo-accumulation index, probable effect level, enrichment factor and pollution load index were calculated to evaluate the pollution status. Except cadmium, CF values for all the metals ranged between 1≤CF≤3 indicating moderate metal contaminations along the coast. Mean PEL quotient (Qm-PEL) indicated toxicity probability to be below 21%. Fe, Cu, Zn and Co showed significant positive correlation (p<0.01) with clay. Chromium was the only metal that demonstrated strong negative correlation with clay (p<0.01) and positive correlation (p<0.01) with sand content.

Imprint of monsoonal patterns on the fish assemblage in coastal waters of south-east India: a case study.

The composition, species richness and diversity of a coastal fish assemblage from the Kalpakkam coast of south-east India are described along with temporal distribution patterns related to seasonal fluctuations in dissolved oxygen, salinity, pH, chlorophyll-a, phytoplankton and zooplankton species richness and density. A total of 244 fish species belonging to 21 orders, 87 families and 163 genera were recorded. The fish assemblage was dominated by reef-associated species, followed by demersal species. The majority of the species (63%) are widely distributed in the western Indo-Pacific as well as in the central Indo-Pacific. Jaccards coefficient analysis showed three distinct seasonal patterns of fish occurrence: pre-monsoon (PrM), monsoon (M) and post-monsoon (PoM). The maximum number of species was during the PrM period, followed by the PoM and M periods. Species occurrence analysis showed Sardinella longiceps to be dominant during PrM and M periods, Leiognathus dussumieri during the M period and Secutor insidiator and Secutor ruconius during the M and PoM periods. Canonical correspondence analysis indicated that salinity and rainfall were the two most influential environmental factors strongly correlated with temporal variation in the fish assemblage. The physico-chemical conditions, in combination with factors such as greater food availability and shelter, might control the seasonal local distribution of the ichthyofauna in these Indian coastal waters.

Larval abundance and its relation to macrofouling settlement pattern in the coastal waters of Kalpakkam, southeastern part of India

The present work revealed that salinity, water temperature, and food availability were the most crucial factors affecting the abundance of larvae and their settlement as macrofouling community in the coastal waters of Kalpakkam. Quantitative as well as qualitative results showed that late post-monsoon (April–May) and pre-monsoon (June–September) periods were found to be suitable periods for larval growth, development, and survival to adult stages for most of the organisms. Clustering of physico-chemical and biological (including larval and adult availability) data yielded two major clusters; one formed by northeast (NE) monsoon months (October–January) and the other by post-monsoon/summer (February–May) months, whereas; pre-monsoon months (June–September) were distributed between these two clusters. Among all the major macrofouler groups, only bivalves established a successful relationship between its larval abundance and adult settlement. Principal component analysis indicated good associations of bivalve larvae with polychaete larvae and adult bivalves with adult barnacles. However, biotic relation between ascidians and bryozoans was observed both in the larval as well as adult community.

A new species of the genus Scolopsis Cuvier, 1830 (Perciformes: Nemipteridae) from southern India and Sri Lanka

Scolopsis igcarensis, a new species of monocle bream (family Nemipteridae) from the coastal waters of southern India and Sri Lanka is described. The species is distinguished from other species of the genus Scolopsis by a combination of the following characters: scales on top of head reaching forward to between anterior nostril and snout tip; lower margin of eye below the line from snout tip to upper pectoral fin base; a bony ridge below eye; a white band from behind eye to level of end of dorsal fin base.