Ecology And Seasonal Variation Of Microalgal Community In An Oil Refinery Effluent Holding Pond: Monitoring And Assessment

The microalgal community as primary producers has to play a significant role in the biotic and abitoic interactions of any aquatic ecosystem. Whenever a community is exposed to a pollutant, responses can occur because individuals acclimate to pollutant caused changes and selection can occur favouring resistant genotypes within a population and selection among species can result in changes in community structure. The microalgal community of industrial effluent treatment systems are continuously exposed to pollutants and there is little data available on the structure and seasonal variation of microalgal community of industrial effluent holding ponds, especially of a complex effluent like that of refinery. The aim of the present study was to investigate the annual variation in the ecology, biomass, productivity and community structure of the algal community of a refinery effluent holding pond. The results of the study showed the pond to be a eutrophic system with a resistant microalgal community with distinct seasonal variation in species composition

STUDIES ON TAXONOMY, DISTRIBUTION, ECOLOGY AND REPRODUCTIVE POTENTIAL OF ROTIFERS FROM SELECTED CENTRES IN COCHIN BACKWATER SYSTEM, KERALA

The studies were conducted in nine stations with varying ecological characteristics along Cochin backwaters and adjoining canals. Many workers opined that the distribution of rotifers is cosmopolitan. The significance of rotifers as first food for early larvae was indicated by Fujita. Aquaculture is a fast growing field in fisheries sector and it is gaining more importance as the fish landings and supply are getting irregular. A consistent supply of fish/shellfish can only be achieved through aquaculture. The success of any culture activity depends on the timely production of seeds of finfishes/shellfishes. The availability of wild seed is seasonal and erratic. So, a dependable source of seed of fishes and shellfishes is possible only through large scale production in hatchery. A successful seed production activity depends on the availability of a variety of suitable live feed organisms in sufficient quantities at the proper time for use in the larval stages. As the live feeds promote high growth rates, easy digestion, assimilation and the quality of not contaminating the culture water when compared to other artificial feeds, make the culture of live feed organisms the principal means of providing food for the larvae of finfishes and shellfishes. Rotifers are considered to be an excellent and indispensable food for larvae of many finfishes and crustaceans. It (1960) was the first to culture Brachionus plicatilis for feeding marine fish larvae, and now it is being extensively used as live feed in hatcheries all over the world. They are a group of microscopic organisms coming under the Phylum Rotifera which comprises of about 2000 species. Their slow swimming habits, ability to tolerate a wide range of salinities, parthenogenetic mode of reproduction and ability to get enriched easily, make rotifers an ideal live feed organism. The major factors such as temperature, salinity and food that influence the reproductive potential and thereby the population size of rotifer, Salinity is one of the most important aspect influencing the reproductive rate of rotifers. The feed type and feed concentration play a vital role in influencing the reproductive rate of rotifers. For culture of rotifers, the commonly used micro algae belong to Chlorella, Nannochloropsis, Isochrysis and Tetraselmis. While some studies have suggested that, algal diet has little effect on reproductive rates in 1979 while using the rotifer, Brachionus plicatilis as feed for the larvae of red sea bream, Pagrus major. It is generally accepted that rotifers play a pivotal role in the successful rearing of marine fish larvae.

Benthic ecology of selected prawn culture fields and ponds near Cochin

The thesis on the"Benthic ecology of selected prawn culture fields and ponds near Cochin” was taken up with a view to provide information on the qualitative and quantitative distribution of benthos and their relationships to prawnproduction of different culture ecosystems and to the physico-chemical parameters influencing their production. A two-year observation was carried out in nine selected prawn culture systems including perennial ponds (stations 1 to 4) seasonal fields (stations 5 to 7) and contiguous canals (stations 8 and 9) during December 1988 to November 1989. All macro- and meiobenthic organisms contributing to the faua were identified and their abundance, distribution, diversity, biomass and trophic relationships between benthos and prawns were studied. The environmental variables studied were temperature pH, salinity, dissolved oxygen, alkalinity, nitrite-nitrogen, nitrate-nitrogen, amonianitrogen, phosphate and silicate of bottom water and organic carbon and texture of the soil The thesis is presented in 4 Chapters. Chapter I presents an’ INTRODUCTION to the topic of study and a review of relevant works to bring an awareness to the present status of research in benthos and benthic ecology. Chapter 11, MATERIALS AND MTHODS, includes the techniques of sampling, preservation of samples and methods of analyses of various physico-chemical factors and area covered under the study is also given in this chapter. Chapter III, HYDROGRAPHY deals with the results of investigation and discussion onthe physico-chemical parameters of water and Chapter IV, SEDIMENT covers the sedimentoloical characteristics of the different culture systems followed by a detailed discussion. Chapter V, BOTTOM FAUNA presents an account on the various aspects of benthos and benthic ecology and the details of prawn production. A discussion on the overall assessment of interrelations between abiotic and biotic factors is given in Chapter VI, DISCUSSION. A critical evaluation of the implication of benthic production on prawn production under culture conditions and trophic relationships are also included in this chapter. An executive SUMMARY of the observations made during this study is presented in the final section of the thesis .

Some observations on the ecology and biochemical aspects of the seaweeds of Kerala coast

In the present thesis , observations on the ecology of seaweed flora of Kerala, their distribution and zonation pattern, monthly/seasonal density of seaweeds at each station, frequency of occurrence, standing crop, monthly/seasonal/place-wise data on physico—chemical characters of ambient waters at the stations and their influence on seaweed density have been made. This data will help us in the farming of economically important seaweeds, by providing information on the ideal conditions of seaweed biomass production. Biochemical observations on protein, carbohydrate and lipid contents of different species of nutritive value. Seaweeds with high content of proteins, carbohydrates and lipids can be recommended for food and feed formulations after subjecting them to toxicological studies. The study on monthly/seasonal/placewise variation in biochemical composition of seaweeds will provide necessary information on the appropriate time and place of harvesting the algal species for exploiting its constituents .

Population Biology And Ecology Of Artemia From Salinas Of South East Coast Of India

This thesis deals with the population characteristics of Artemia and the effect of different environmental parameters on the different stages of Artemia in a salina at Tuticorin, south east coast of India. The present investigation was carried out from 1985 to I987. The study was initiated by undertaking a survey to find out suitable Artemia habitats along the south east coast of India and a perennial salina with an area of 0.25 ha was selected at Karapad (Tuticorin). Weekly samplings were made for two full calender years (1986-87) to collect the different stages of Artemia population as well as the different environmental parameters. The thesis comprises of the following sections: Introduction, materials and methods, systematics, biology and distribution of Artemia, results and discussion, summary and bibliography. The section on results and discussion gives the characteristics of Artemia population in the salina, the seasonal variations of different environmental parameters in the salina and their effects on different stages of Artemia population. Description of an experiment conducted to show the sudden changes of salinity on different stages of Artemia is also given as a separate section.

Studies on The Ecology And Production of Algae in Prawn Culture Systems

Existing method of culture were largely based on empirical knowledge. Lacking a scientific basis as such methods did, they were often wasteful and suffered severe limitation. Modern methods of fish and prawn culture based on scientific research, have revolutioned the industry in recent years and not only extended its scope to cover the whole country but led to increased fish and prawn production. An understanding of the biological capability of the water in the perennial and seasonal culture ponds, and the nature and extent of the influence of the abiotic factors on the production of organisms in the primary level of food chain would contribute to effectively implement management measures in the stocking strategies and in the evaluation of economics of production of prawns. It is against this background that the present topic of investigation "Studies on the ecology and production of algae in prawn culture systems” was selected.

Seasonal Variability Of Dissolved Nutrients In Mangrove Ecosystems Along South West Coast Of Kerala, India

The mangroves of Kerala are fast disappearing due to developmental activities.There are very few studies conducted in the chemical aspects of these ecosystems.The main objective of this study is to assess the spatial and seasonal variation of hydrographical as well as nutrients in mangrove ecosystems along Kerala coast. Five sampling sites least intervened by industries were selected for the study. Sampling was done for a period of six months in monthly intervals. A monsoonal hike of dissolved nutrients was observed in all ecosystems except in the constructed mangrove wetland. The constructed wetland exhibited a different hydrography and nutrient level in all seasons. The mangrove forest in this area consists of the species Bruguiera gymnorrhiza which has been planted since forty years.

Salinity Intrusion and Seasonal Water Quality Variations in the Tidal Canals of Cochin

The study conducted on the salinity intrusion and seasonal water quality variations in the tidal canals of cochin. The main objectives are, salinity intrusion profile, water quality variation of the surface water of the canals,hierarchical utility of the water bodies and to understand the non-conservative components in the water body. The parameters monitored werepH,temperature,alkalinity,conductivity,DO(dissolvedoxygen),COD(chemical oxygen demand),BOD(biochemical oxygen demand0,chloride, total hardness, calcium hardness, dissolved phosphate, nitrate, total iron, sulphate, turbidity, total coliform and SUVA at 254nm. The tidal canals of GCDA were found to be creeks extending to the interior, canals inter connecting parts of the estuary or canals with seasonally broken segments. Based on utility the canals could be classified as: canals heavely polluted and very saline,canals polluted by urban waste , canals having fresh water for most part of the year and not much polluted, fresh water bodies heavily polluted. During the rainy months carbon fixation by plankton is nonexistent,and during the dry months Chitrapuzha becomes a sink of phosphate. The study indicated abiotic subrouts for dissolved phosphate and revealed the potential pitfalls in LOICZ modeling exercise on sewage ladentidal canals. It was also found that all canals except for the canals of West cochin and chittoorpuzha have fresh water for some part of the year. The water quality index in the durable fresh water stretches was found to be of below average category.

Seasonal Studies on Primary Production and Associated Environmental Parameters in the Indian EEZ

The thesis describes the importance of Indian EEZ, definition and the various factors affecting primary production, general account of phytoplankton and its importance in marine ecosystem etc. In review of literature, general oceanography of Arabian Sea and Bay of Bengal and hydrography of eastern Arabian Sea and western Bay of Bengal. It deals with the distribution patterns of primary production, chlorophyll a, phytoplankton composition and particulate organic carbon in the eastern Arabian Sea and western Bay of Bengal during different seasons. Factors that affect primary productivity are irradiance, temperature, stability of the surface waters, nutrients and zooplankton grazing. The differential biological response of eastern Arabian Sea and western Bay of Bengal to monsoonal regimes. A precise estimation on the primary production of the entire EEZ of India on a regional basis and on a seasonal scale would be the only way to achieve any kind of predictive assessment on the fish stock and their sustainable yield. This study mainly envisages the qualitative and quantitative aspects on the magnitude of phytoplankton standing crop and production of organic carbon and their relationship to environmental characteristics during summer monsoon, Inter monsoon and winter monsoon periods in the east and west coasts of the Indian EEZ.This study revealed that the seasonality exerts a great impact on the biological production in the eastern Arabian Sea and western Bay of Bengal. High biological production may be the reason why most of the fish landings are Concentrated in the west coast of India than east coast. The present data on Phytoplankton production rate and the species composition will provide a meaningful ground for evaluations of exploitable renewable resources of the IndianEEZ

Seasonal ramification in the biochemical composition of organic matter in Chalakudy river-estuary

The present study which is the first of its kind in this region is an attempt to generate adequate information on the relative abundances, the seasonal and spatial variations as well as on the source and fate of organic compounds found associated with the dissolved, particulate and sedimentary compartments of Chalakudy river system. The study aimed at investigating variations, the relative proportion of dissolved, particulate and sedimentary fractions of these materials as well as the pollution extent so as to be able to comment on the present condition of this river-estuarine system. This thesis focuses attention on the role of biogeoorganics in modifying the ecological and environmental condition of the dissolved, particuIate and sediment compartments with their minute variability subjected to various physical, chemical and biogeochemical processes. A scheme of study encompassing all these objectives provides the frame work for the present investigation.

lmpact of bottom trawling on benthic ecology along the coastal waters of Kerala with special reference to meiofauna

School of Industrial Fisheries, Cochin University of Science and Technology