Investlgations On The Chemical Constituents And Trace Metal Interactions In Some Bivalve Moll.USCS Of The Cochin Backwaters

The subsequent chapters of the Thesis deal with the toxic effects of mercury, copper, zinc und~1ead on these bivalve molluecs, their accumulation and distribution among various organs of the animals and also the motel retention winstica by the three species. Static biousauy tests have been conducted in these studies. It was found that the concentrations of the various metals studied in these organism are well below the permitted level given far ease ahellfienes (crab and ehrimgi and that these maliuscs are very good integrators ef trace metals from their environment and may be used as an indicator organism sf metal pallutaute. The present investigutionsemphaeie the need for a clean coastal water and gives a serious warning regarding the possiblc route of heavy metals in ta human body thraugh marine food chain.

“Hydro Geochemical Quality Assessment of Groundwater – A General Perspective”

People in several parts of the world as well in India countenance an immense confront to meet the basic needs of water. The crisis is not due to lack of fresh water but its availability in adequate superiority. Environmental quality objectives should be developed in order to define acceptable loads on the terrain. There has been a number of initiatives in water quality monitoring but the next step towards improving its quality hasn’t taken the required pace. Today, there is a growing need to create awareness among citizens on the different technologies available for improving the water quality. Monitoring facilitate to apprehend how land and water use distress the quality of water and assist in estimating the extent of pollution. Once these issues are recognized, people can work towards local solutions to manage the indispensable resource effectively. Ground waters are extremely precious resources and in many countries together with India they represent the most important drinking water supply. They are generally microbiologically pure and, in most cases, they do not need any treatment. This communiqué is intended to act as a channel on the various paraphernalia and techniques accessible for groundwater quality assessment and suggesting the assured precautionary measures to embark on environment management. This learning is imperative considering that groundwater as the exclusive source of drinking water in the region which not makes situation alarming but also calls for immediate attention. The scope of this work is somewhat vast. Water quality in Ernakulam district is getting deteriorated due to the fast growth of urbanization. The closure of several water bodies due to land development and construction prevents infiltration of rainwater into the ground and hence recharge the aquifers. Most of the aquifers are getting polluted from the industrial effluents and chemicals and fertilizers used in agriculture. Such serious issues require proper monitoring of groundwater and steps are to be taken for remedial measures. This study helps in the total protection of the rich resource of groundwater and its sustainability. Socio-economic aspect covered could be used for conducting further individual case studies and to suggest remedial measures on a scientific basis. The specific study taken up for 15 sites can be further extended to the sources of pollution, especially industrial and agriculture

Systematics and pathogenicity of vibrionaceae associated with the larvae of macrobrachium rosenbergii in hatchery

The great potential for the culture of non-penaeid prawns, especially Macrobrachium rosenbergii in brackish and low saline areas of Indian coastal zone has not yet been fully exploited due to the non availability of healthy seed in adequate numbers and that too in the appropriate period. In spite of setting up several prawn hatcheries around the country to satiate the ever growing demands for the seed of the giant fresh water prawn, the supply still remains fear below the requirement mainly due to the mortality of the larvae at different stages of the larval cycle. In a larval rearing system of Macrobrachium rosenbergii, members of the family Vibrionaceae were found to be dominant flora and this was especially pronounced during the times of mortality However, to develop any sort of prophylactic and therapeutic measures, the pathogenic strains have to be segregated from the lot. This would never be possible unless they were clustered based on the principles of numerical taxonomy It is with these objectives and requirements that the present work involving phenotypic characterization of the isolates belonging to the family Vibrionaceae and working out the numerical taxonomy, determination of mole % G+C ratio, segregation of the pathogenic strains and screening antibiotics as therapeutics at times of emergency, was carried out.

Diversity and antimicrobial activity of Lactic Acid Bacteria from the gut of marine fish Rastrelliger kanagurta against fish, shrimp and human pathogens

Emergence of antibiotic resistance among aquaculture pathogens has made it necessary to look into environment friendly, effective and sustainable methods such as probiotic and immunostimulants among others.. In the present study, LAB were isolated from the gut of fish species namely Rastrelliger kanagurta and analyzed for their antibacterial activity against various fish, shrimp and human pathogens. Different LAB species such as Lactobacillus plantarum, L. bulgaricus, L. brevis and L. viridiscens were encountered in the gut of R. kanagurta. Several strains showed good activity against fish, shrimp and human pathogens. LAB from the gut of such marine species may be developed as possible probiont for environment friendly health management of fresh water, estuarine and marine species currently exploited in aquaculture

Application of bacterins and yeast Acremonium dyosporii to protect the larvae of Macrobrachium rosenbergii from vibriosis

The fresh water prawn, Macrobrachium rosenbergii, has proven potential for use as an aquaculture species (Hanson & Goodwin, 1997; Kurup, 1984). In India alone, culture of this species of prawn in low saline areas requires about 200 million seed per year (Kurup, 1984). In hatcheries poor survival rate has been associated with vibriosis at di#erent stages of the larval cycle. Members of the family Vibrionaceae associated with the larvae of M. rosenbergii were shown to be pathogenic under laboratory conditions (Bhat et al., 2000, in press). Vibrios have been associated with mortality of penaeid prawns by several workers (Aquacop, 1977; Hameed, 1993; Karunasagar et al., 1994). Two methods have been suggested to protect both the larvae and juveniles from vibriosis; one is the administration of bacterins prepared from pathogenic strains (Itami et al., 1989, 1991; Adams, 1991; Song & Sung, 1990; Sung et al., 1991) and the other is the utilization of yeast 1-3 and 1-6 glucans as immunostimulants for enhancing the non-specific defense system (Sung et al., 1994; Song et al., 1997). In the light of these observations it was hypothesised that bacterins and yeast glucans may also be e#ective in protecting the larvae of M. rosenbergii from vibriosis as has been achieved in the case of penaeids. To examine this hypothesis, the ability of bacterins and an extracellular glucan-producing yeast to increase the overall survival and metamorphosis of larvae in a hatchery, as well as to protect against an experimental challenge under laboratory conditions, was evaluated

The Ratios of Carbon, Nitrogen, and Phosphorus in a Wetland Coastal Ecosystem of Southern India

The fertility of the coastal and estuarine waters is of great concern because of its influence on the productivity of these waters. Seasonal variations in the distribution of organic carbon, total nitrogen and total phosphorus in the sediments of Kuttanad Waters, a part of the tropical Cochin Estuary on the south west coast of India, are examined to identify the contribution of sediments to the fertility of the aquatic systems. The adjoining region has considerable agricultural activity. The fresh water zones had higher quantities of silt and clay whereas the estuarine zone was more sandy. Organic carbon, total phosphorus and total nitrogen were higher in the fresh water zones and lower in the estuarine zones. Total phosphorus and organic carbon showed the lowest values during monsoon periods. No significant trends were observed in the seasonal distributions of total nitrogen. Ratios of C/N, C/P and N/P, and the phosphorus and nitrogen content indicate significant modification in the character of the organic matter. Substantial amounts of the organic matter can contribute to reducing conditions and modify diagenetic processes

Dezincification of Epoxy Coated Brass in Cochin Estuary, India

Inhibited α brasses are largely immune to dezincification in most water, but the effect of tin and arsenic addition to α/β brasses is not so reliable or predictable in controlling the problem. There have been many cases of dezincification in duplex brasses in both fresh water and seawater. There is no reliable method of inhibiting the dezincification of two-phase brass despite there are some protection methods such as inhibitors, electro deposition and electro polymerization. Organic coatings are effectively used for the protection of metals due to their capacity to act as a physical barrier between the metal surface and corrosive environment. Hence, epoxy coating on brass was applied and effect of this against dezincification in Cochin estuarine water over a period of one year was studied and reported in this paper

Hydrogeology and hydrochemistry of the aquifer systems of Kuttanad area, Kerala: Their role in understanding the evolution of groundwaters

This is an attempt to understand the important factors that control the occurrence, development and hydrochemical evolution of groundwater resources in sedimentary multi aquifer systems. The primary objective of this work is an integrated study of the hydrogeology and hydrochemistry with a view to elucidate the hydrochemical evolution of groundwater resources in the aquifer systems. The study is taken up in a typical coastal sedimentary aquifer system evolved under fluvio-marine environment in the coastal area of Kerala, known as the Kuttanad. The present study has been carried out to understand the aquifer systems, their inter relationships and evolution in the Kuttanad area of Kerala. The multi aquifer systems in the Kuttanad basin were formed from the sediments deposited under fluvio-marine and fluvial depositional environments and the marine transgressions and regressions in the geological past and palaeo climatic conditions influenced the hydrochemical environment in these aquifers. The evolution of groundwater and the hydrochemical processes involved in the formation of the present day water quality are elucidated from hydrochemical studies and the information derived from the aquifer geometry and hydraulic properties. Kuttanad area comprises of three types of aquifer systems namely phreatic aquifer underlain by Recent confined aquifer followed by Tertiary confined aquifers. These systems were formed by the deposition of sediments under fluvio-marine and fluvial environment. The study of the hydrochemical and hydraulic properties of the three aquifer systems proved that these three systems are separate entities. The phreatic aquifers in the area have low hydraulic gradients and high rejected recharge. The Recent confined aquifer has very poor hydraulic characteristics and recharge to this aquifer is very low. The Tertiary aquifer system is the most potential fresh water aquifer system in the area and the groundwater flow in the aquifer is converging towards the central part of the study area (Alleppey town) due to large scale pumping of water for water supply from this aquifer system. Mixing of waters and anthropogenic interferences are the dominant processes modifying the hydrochemistry in phreatic aquifers. Whereas, leaching of salts and cation exchange are the dominant processes modifying the hydrochemistry of groundwater in the confined aquifer system of Recent alluvium. Two significant chemical reactions modifying the hydrochemistry in the Recent aquifers are oxidation of iron in ferruginous clays which contributes hydrogen ions and the decomposition of organic matter in the aquifer system which consumes hydrogen ions. The hydrochemical environment is entirely different in the Tertiary aquifers as the groundwater in this aquifer system are palaeo waters evolved during various marine transgressions and regressions and these waters are being modified by processes of leaching of salts, cation exchange and chemical reactions under strong reducing environment. It is proved that the salinity observed in the groundwaters of Tertiary aquifers are not due to seawater mixing or intrusion, but due to dissolution of salts from the clay formations and ion exchange processes. Fluoride contamination in this aquifer system lacks a regional pattern and is more or less site specific in natureThe lowering of piezometric heads in the Tertiary aquifer system has developed as consequence of large scale pumping over a long period. Hence, puping from this aquifer system is to be regulated as a groundwater management strategy. Pumping from the Tertiary aquifers with high capacity pumps leads to well failures and mixing of saline water from the brackish zones. Such mixing zones are noticed from the hydrochemical studies. This is the major aquifer contamination in the Tertiary aquifer system which requires immediate attention. Usage of pumps above 10 HP capacities in wells taping Tertiary aquifers should be discouraged for sustainable development of these aquifers. The recharge areas need to be identified precisely for recharging the aquifer systems throughartificial means.

Studies on nitrifying microorganisms in Cochin Estuary and adjacent coastal waters

This thesis entitled “Studies on Nitrifying Microorganisms in Cochin Estuary and Adjacent Coastal Waters” reports for the first time the spatial andtemporal variations in the abundance and activity of nitrifiers (Ammonia oxidizingbacteria-AOB; Nitrite oxidizing bacteria- NOB and Ammonia oxidizing archaea-AOA) from the Cochin Estuary (CE), a monsoon driven, nutrient rich tropicalestuary along the southwest coast of India. To fulfil the above objectives, field observations were carried out for aperiod of one year (2011) in the CE. Surface (1 m below surface) and near-bottomwater samples were collected from four locations (stations 1 to 3 in estuary and 4 in coastal region), covering pre-monsoon, monsoon and post-monsoon seasons. Station 1 is a low saline station (salinity range 0-10) with high freshwater influx While stations 2 and 3 are intermediately saline stations (salinity ranges 10-25). Station 4 is located ~20 km away from station 3 with least influence of fresh water and is considered as high saline (salinity range 25- 35) station. Ambient physicochemical parameters like temperature, pH, salinity, dissolved oxygen (DO), Ammonium, nitrite, nitrate, phosphate and silicate of surface and bottom waters were measured using standard techniques. Abundance of Eubacteria, total Archaea and ammonia and nitrite oxidizing bacteria (AOB and NOB) were quantified using Fluorescent in situ Hybridization (FISH) with oligonucleotide probes labeled withCy3. Community structure of AOB and AOA was studied using PCR Denaturing Gradient Gel Electrophoresis (DGGE) technique. PCR products were cloned and sequenced to determine approximate phylogenetic affiliations. Nitrification rate in the water samples were analyzed using chemical NaClO3 (inhibitor of nitrite oxidation), and ATU (inhibitor of ammonium oxidation). Contribution of AOA and AOB in ammonia oxidation process was measured based on the recovered ammonia oxidation rate. The contribution of AOB and AOA were analyzed after inhibiting the activities of AOB and AOA separately using specific protein inhibitors. To understand the factors influencing or controlling nitrification, various statistical tools were used viz. Karl Pearson’s correlation (to find out the relationship between environmental parameters, bacterial abundance and activity), three-way ANOVA (to find out the significant variation between observations), Canonical Discriminant Analysis (CDA) (for the discrimination of stations based on observations), Multivariate statistics, Principal components analysis (PCA) and Step up multiple regression model (SMRM) (First order interaction effects were applied to determine the significantly contributing biological and environmental parameters to the numerical abundance of nitrifiers). In the CE, nitrification is modulated by the complex interplay between different nitrifiers and environmental variables which in turn is dictated by various hydrodynamic characteristics like fresh water discharge and seawater influx brought in by river water discharge and flushing. AOB in the CE are more adapted to varying environmental conditions compared to AOA though the diversity of AOA is higher than AOB. The abundance and seasonality of AOB and NOB is influenced by the concentration of ammonia in the water column. AOB are the major players in modulating ammonia oxidation process in the water column of CE. The distribution pattern and seasonality of AOB and NOB in the CE suggest that these organisms coexist, and are responsible for modulating the entire nitrification process in the estuary. This process is fuelled by the cross feeding among different nitrifiers, which in turn is dictated by nutrient levels especially ammonia. Though nitrification modulates the increasing anthropogenic ammonia concentration the anthropogenic inputs have to be controlled to prevent eutrophication and associated environmental changes.

Provenance, Isolation and Characterisation of Organic Matter in the Cochin Estuarine Sediment-“a Diagenetic Amino Acid Marker Scenario

Cochin estuarine system is among the most productive aquatic environment along the Southwest coast of India, exhibits unique ecological features and possess greater socioeconomic relevance. Serious investigations carried out during the past decades on the hydro biogeochemical variables pointed out variations in the health and ecological functioning of this ecosystem. Characterisation of organic matter in the estuary has been attempted in many investigations. But detailed studies covering the degradation state of organic matter using molecular level approach is not attempted. The thesis entitled Provenance, Isolation and Characterisation of Organic Matter in the Cochin Estuarine Sediment-“ A Diagenetic Amino Acid Marker Scenario” is an integrated approach to evaluate the source, quantity, quality, and degradation state of the organic matter in the surface sediments of Cochin estuarine system with the combined application of bulk and molecular level tools. Sediment and water samples from nine stations situated at Cochin estuary were collected in five seasonal sampling campaigns, for the biogeochemical assessment and their distribution pattern of sedimentary organic matter. The sampling seasons were described and abbreviated as follows: April- 2009 (pre monsoon: PRM09), August-2009 (monsoon: MON09), January-2010 (post monsoon: POM09), April-2010 (pre monsoon: PRM10) and September- 2012 (monsoon: MON12). In order to evaluate the general environmental conditions of the estuary, water samples were analysed for water quality parameters, chlorophyll pigments and nutrients by standard methods. Investigations suggested the fact that hydrographical variables and nutrients in Cochin estuary supports diverse species of flora and fauna. Moreover the sedimentary variables such as pH, Eh, texture, TOC, fractions of nitrogen and phosphorous were determined to assess the general geochemical setting as well as redox status. The periodically fluctuating oxic/ anoxic conditions and texture serve as the most significant variables controlling other variables of the aquatic environment. The organic matter in estuary comprise of a complex mixture of autochthonous as well as allochthonous materials. Autochthonous input is limited or enhanced by the nutrient elements like N and P (in their various fractions), used as a tool to evaluate their bioavailability. Bulk parameter approach like biochemical composition, stoichiometric elemental ratios and stable carbon isotope ratio was also employed to assess the quality and quantity of sedimentary organic matter in the study area. Molecular level charactersation of free sugars and amino acids were carried out by liquid chromatographic techniques. Carbohydrates are the products of primary production and their occurrence in sediments as free sugars can provide information on the estuarine productivity. Amino acid biogeochemistry provided implications on the system productivity, nature of organic matter as well as degradation status of the sedimentary organic matter in the study area. The predominance of carbohydrates over protein indicated faster mineralisation of proteinaceous organic matter in sediments and the estuary behaves as a detrital trap for the accumulation of aged organic matter. The higher lipid content and LPD/CHO ratio pointed towards the better food quality that supports benthic fauna and better accumulation of lipid compounds in the sedimentary environment. Allochthonous addition of carbohydrates via terrestrial run off was responsible for the lower PRT/CHO ratio estimated in thesediments and the lower ratios also denoted a detrital heterotrophic environment. Biopolymeric carbon and the algal contribution to BPC provided important information on the better understanding the trophic state of the estuarine system and the higher values of chlorophyll-a to phaeophytin ratio indicated deposition of phytoplankton to sediment at a rapid rate. The estimated TOC/TN ratios implied the combined input of both terrestrial and autochthonous organic matter to sedimentsAmong the free sugars, depleted levels of glucose in sediments in most of the stations and abundance of mannose at station S5 was observed during the present investigation. Among aldohexoses, concentration of galactose was found to be higher in most of the stationsRelative abundance of AAs in the estuarine sediments based on seasons followed the trend: PRM09-Leucine > Phenylalanine > Argine > Lysine, MON09-Lysine > Aspartic acid > Histidine > Tyrosine > Phenylalanine, POM09-Lysine > Histadine > Phenyalanine > Leucine > Methionine > Serine > Proline > Aspartic acid, PRM10-Valine > Aspartic acid > Histidine > Phenylalanine > Serine > Proline, MON12-Lysine > Phenylalanine > Aspartic acid > Histidine > Valine > Tyrsine > MethionineThe classification of study area into three zones based on salinity was employed in the present study for the sake of simplicity and generalized interpretations. The distribution of AAs in the three zones followed the trend: Fresh water zone (S1, S2):- Phenylalanine > Lysine > Aspartic acid > Methionine > Valine ῀ Leucine > Proline > Histidine > Glycine > Serine > Glutamic acid > Tyrosine > Arginine > Alanine > Threonine > Cysteine > Isoleucine. Estuarine zone (S3, S4, S5, S6):- Lysine > Aspartic acid > Phenylalanine > Leucine > Valine > Histidine > Methionine > Tyrosine > Serine > Glutamic acid > Proline > Glycine > Arginine > Alanine > Isoleucine > Cysteine > Threonine. Riverine /Industrial zone (S7, S8, S9):- Phenylalanine > Lysine > Aspartic acid > Histidine > Serine > Arginine > Tyrosine > Leucine > Methionine > Glutamic acid > Alanine > Glycine > Cysteine > Proline > Isoleucine > Threonine > Valine. The abundance of AAs like glutamic acid, aspartic acid, isoleucine, valine, tyrosine, and phenylalanine in sediments of the study area indicated freshly derived organic matter.

Polycyclic aromatic hydrocarbons and toxic trace metals in seawater and sediments from the west coast of India and their bioaccumulation in some selected species of fishes

Polycyclic Aromatic Hydrocarbons and other toxic compounds from industrial effluents are noted for their high potency for skin, lung, bladder and gastrointestinal cancers. Increased industrialization, and population growth led to greater production of wastes, Pesticides and PAHs have received attention due to their carcinogenic effects. The main objectives of the study were; to collect base line data on the concentration of PAHs in seawater and sediment from the west coast of India, the concentration of PAHs in certain species of fishes, the comparative levels of PAHs in fish, the influence of sediment characteristics on the concentration of PAH in sediment, changes in PAH concentration in water, sediment and fish, to provide a base line concentration of trace metals in water, sediment and fish, the seasonal changes in content of selected trace metals in water, sediment and fish from the west coast of India. The present study revealed that a predominance of silt and clay at all stations in the off Cochin area. The study has provided comprehensive information available to date for PAHs in seawater, sediment and fishes from the west cost of India especially from the Quilon to Mangalore region.

A Study on the Water Retention Characteristics of Soils and their Improvements

Soil moisture plays a cardinal role in sustaining eclological balance and agricultural development – virtually the very existence of life on earth. Because of the growing shortage of water resources, we have to use the available water most efficiently by proper management. Better utilization of rainfall or irrigation management depends largely on the water retention characteristics of the soil.Soil water retention is essential to life and it provides an ongoing supply of water to plants between periods of irrigation so as to allow their continued growth and survival.It is essential to maintain readily available water in the soil if crops are to sustain satisfactory growth. The plant growth may be retarded if the soil moisture is either deficient or excessive. The optimum moisture content is that moisture which leads to optimum growth of plant. When watering is done, the amount of water supplied should be such that the water content is equal to the field capacity that is the water remained in the saturated soil after gravitational drainage. Water will gradually be utilized consumptively by plants after the water application, and the soil moisture will start falling. When the water content in the soil reaches the value known as permanent wilting point (when the plant starts wilting) fresh dose of irrigation may be done so that water content is again raised to the field capacity of soil.Soil differ themselves in some or all the properties depending on the difference in the geotechnical and environmental factors. Soils serve as a reservoir of the nutrients and water required for crops.Study of soil and its water holding capacity is essential for the efficient utilization of irrigation water. Hence the identification of the geotechnical parameters which influence the water retention capacity, chemical properties which influence the nutrients and the method to improve these properties have vital importance in irrigation / agricultural engineering. An attempt in this direction has been made in this study by conducting the required tests on different types of soil samples collected from various locations in Trivandrum district Kerala, with and without admixtures like coir pith, coir pith compost and vermi compost. Evaluation of the results are presented and a design procedure has been proposed for a better irrigation scheduling and management.

Systematics and biology of Fishes of family of the hemiramphidae of Cochin coast

This overall focus of the thesis involves the systematics and biology of fishes of the family hemiramphidae of cochin coast.India is one of the leading fish producing nations in the world with an average annual production of 6.1 million tonnes of fish and shell fish from capture and culture fisheries in 2001 (Ayyappan and Biradar, 2002).Fisheries play a very significant role in the Indian economy by providing employment to nearly 7 million people directly or indirectly, supplying rich protein food and earning valued foreign exchange.Fishes of the family Hemiramphidae are commonly called ‘half beaks‘.In India, studies on hemiramphids commenced with the work of Day (1878,1889) who recorded thirteen species of hemiramphids from the Indian waters.The study area, which is part of Cochin coast is located between Lat.9°28’ and 10° N and Long.76° 13’ and 76° 31 E. Lying parallel to it is an estuary which is commonly called the Cochin backwaters which has a total area of about 200 sq.miles.The study area is subjected to wide variations in salinity from place to place, season and surface to bottom.The Cochin coast and the adjacent back water system of Kerala has a rich and diversified fish fauna. The hemiramphid fishes constitute a minor fishery of this area.The study on the distribution and availability of hemiramphid fishes present in the Cochin coast shows that they evince different patterns of distribution.In the present study it is noticed that fecundity has high correlation with weight than length of the fish.Histological studies revealed that the spermatogenesis in both H. (H) limbatus and H.(H) xanthopterus, consists of spermatogonia, primary spermatocytes secondary, spermatocytes, spermatids and spermatozoa whereas in the oogenesis of both the species.biological study will be useful in implementation of proper measures of conservation and management so that further devastation of the hemiramphids of Cochin Coast can be controlled.

Resource abundance and Survival of indigenous ornamental fishes of central Kerala with emphasis on handling and packing stress in Puntius filamentosus(VALENCIENNES)

This thesis Entitled Resource abundance and survival of indigenous ornamental fishes of central kerala with emphasis on handling and packing stress in puntius filamentosus (valenciennes).Kerala state is endowed with 41 west flowing and three east flowing rivers originating in the Western Ghats. These rivers and their vast network of tributaries and distributaries harbour rich and diversified fish fauna. Most of the freshwater fishes available in Kerala are highly appreciated as ornamental fishes in the national and international markets.Today the ornamental fish industry is one of the largest industries all over the world. The demand for ornamental fishes has been increasing steadily with the enlargement of the industry, such that the current demand for indigenous ornamental fishes have exceeded the supply. This has led to serious concern about the resources available in the country that can be utilised judiciously for the economic benefit of the state. With an aim to fill up the lacuna, a database of freshwater ornamental fishes of Kerala was created as part of the present study. Ornamental fishes destined for export marketing should thrive well in the aquarium conditions.The study reiterates fishes caught from different environmental conditions and feeding habits have a greater ability to adapt and acclimatise to an entirely new environment and food habits. Marketing studies based on the statistics available with Marine Products Export Development Authority show that these species are not being exported at the required level over the past 6 years, when compared to the availability in the water bodies of Kerala. Sustainable utilisation of these resources from the wild using modern management principles and code of conduct for responsible fishing are advisable until captive breeding technology is popularised.

Haematological and Toxicological studies on brackish water fish Etroplus maculatus (Bloch)”

Fishes are one of the most important members of the aquatic food chain, and through them some toxicants may reach human beings as well. The selection of organisms for toxicity test is mainly based on certain criteria like its ecological status, position within the food chain, suitability for laboratory studies, genetically stable, uniform populations and adequate background data on the organism (Buikema et al., 1982). The species selected for the present study Etroplus maculatus satisfy most of the above protocols. Rechten (1980) opined it as a laboratory favorite of fish researchers. However, there are difficulties in the rise of fishes for pollution assessment impact. Most important of these is our limited understanding of the mechanism of toxicity. The interpretation of the significance or specificity of a measured biological response could there for become difficult. Not withstanding these limitations, attempts have been made to the normal haematology and to analyze the impact of heavy metal at realistic levels to the experimental media, on the haematology, and enzymatic activity and histology of Etroplus maculatus