Biology- Extended essay. For this research, I investigated the effects of DDT and an Azo-Dye on the opercular movement of Mrigal (Cirrhinus cirrhosus) a fresh water fish.

Authors Avatar

BIOLOGY EXTENDED

            ESSAY


BIOLOGY EXTENDED ESSAY

What effect do the different concentrations of DDT and an AZO dye have on the opercular movement of Cirrhinus cirrhosus?

Biology Supervisor:  Shobit Saxena

Word Count: 4100

CONTENTS

Page No:

  • Research Question……………………………………………………..      2
  • Abstract…………………………………………………………………..      4
  • Introduction………………………………………………………………      5
  • The Operculum and the breathing process of a fish
  • An Introduction to Cirrhinus Cirrhosus
  • About DDT
  • The textile industry
  • What Azo-Dyes are
  • Hypothesis……………………………………………………………….     10
  • Selecting Variables……………………………………………………..     10  
  • Apparatus Required…………………………………………………….     14
  • Procedure………………………………………………………………..     15
  • Investigation I……………………………………………………………     17
  • Investigation II…………………………………………………………...     22
  • Investigation III…………………………………………………………..     27
  • T-Test…………………………………………………………………….     31
  • Conclusion and Evaluation……………………………………………..    32  
  • Extension of the experiment……………………………………………    37
  • Terminology……………………………………………………………..     39
  • Bibliography……………………………………………………………..     41

ABSTRACT

I was inquisitive about the aquatic flora and fauna and their mass destruction due to the increase in chemical pollutants coming from industries, agricultural farms and houses. Therefore I thought and pondered about the reasons behind this destruction and the question which I thought would be worthy of investigation is:

What effect do the different concentrations of DDT and an AZO dye have on the opercular movement of Cirrhinus cirrhosus?

For this research, I investigated the effects of DDT and an Azo-Dye on the opercular movement of Mrigal (Cirrhinus cirrhosus) a fresh water fish. This was attained by performing primary research, which was achieved by setting up 3 similar experiments, first using different concentrations of DDT, second using different concentration of the Azo-Dye and third using a mixture of these two toxins. All the experiments were carried out to find out the difference in opercular movement in fish, as it would help answer my question. For the first and second experiment, I obtained 25 data for each concentration, and 125 data for all the concentrations of DDT including the controlled experiment.  The same was repeated in the third, however data collected was 25 for the mixture and 50 including the controlled experiment.

From the results that I recorded, and observed I can say that DDT, the Azo-Dye and the mixture of these two toxins reduce the opercular movement of Mrigal. The graphs show a clear trend of decline in the opercular movement.  

The results of the three investigations helped me conclude that DDT and the Azo-Dye both have a similar affect on the opercular movement of the fish and that the mixture of these two toxins is collectively more dangerous. These toxins affect the fishes by reducing their opercular movement with an increase in concentration.

Word count: 295

INTRODUCTION

The aim of this extended essay is to find out the effects of industrial pollutants on the breathing rate of Cirrhinus cirrhosus (Mrigal) a fresh water fish. I cover the discipline of science called toxicology in the following experiments. Toxicology is the science of poisons; it deals with the study of economic poisons, their effects, mechanisms of action and metabolism of toxicants in test animals. The two pollutants for which the test will be conducted are DDT (Dichlorodiphenyltrichloroethane) and local textile dyes (Azo-Dyes). Both of which, are found in abundance in Rajasthan, India. These toxins are often a cause of Biomagnification. Mrigal, a fresh water fish which is widely cultured in India will help us replicate the effect of such pollutants in controlled laboratory conditions. Further, to support our results I would carry out a third investigation to see the results of a mixture of these two toxins on the fish. Through an analysis of the three investigations I would like to understand the real effect of these pollutants on our environment. Hence chosing the research question:

“What effect do the different concentrations of DDT and an AZO dye have on the opercular movement of Cirrhinus cirrhosus?

THE OPERCULUM AND THE BREATHING PROCESS OF A FISH:-

The operculum of a fish is the hard bony flap covering and protecting the gills. The operculum is composed of four fused bones; the opercle, preopercle, interopercle, and subopercle. The posterior rim on the operculum is a flexible, ribbed structure which acts as a seal in order to stop reverse water flow during respiration.

For most fish, the operculum is critical in obtaining oxygen. It opens as the mouth closes, causing the pressure inside the fish to drop. Water then flows towards the lower pressure across the fish's gill lamellae, allowing some oxygen to be absorbed from the water.

The movements of the mouth floor and operculum are synchronized to produce a stream of water, in through the mouth, over the gills and out of the operculum.

The method of pumping water over the gills seems to differ in detail according to the type of fish but, in general, the pressure in the mouth cavity is reduced by the floor of the mouth being lowered.

Thus, water enters through the mouth to even out the pressure. The increased pressure due to the reduced volume of the mouth cavity forces open the operculum and expels the water through the opercular opening, causing it to pass between the gill filaments as it leaves.

AN INTRODUCTION TO CIRRHINUS CIRRHOSUS:-

 

The Mrigal is a freshwater fish species from the Carps family of the order Cypriniformes. The Mrigal is an introduced species and is actually native to large river systems of India. The Mrigal, currently is the widest farmed species amongst the Indian floodplains of Bangladesh, India and Pakistan. It is found in the rivers of Myanmar that drain into the Bay of Bengal. It was introduced for the purpose of aquaculture, together with Catla (Catla catla) and Rohu (Labeo rohita) to other areas of India beyond its natural range in the early 1940's and in the 1950's and 1960's to other Asian countries. This particular species of fish will help us in calculating its opercular movement, thus determining the affects DDT and the Azo-Dye on the fish.

ABOUT DDT:-

DDT is probably the most infamous synthetic pesticide obtainable today. DDT is a constant organic pollutant that is exceedingly hydrophobic and greatly absorbed by soils. Its soil half life can range from 22 days to 30 years. Routes of loss and degradation include runoff, volatilization, photolysis and aerobic and anaerobic biodegradation. When added to the aquatic ecosystems it is quickly absorbed by organisms and by soil or it evaporates, leaving little DDT dissolved in the water itself. In my experiments DDT will be added to the fish’s environment and there direct response would be shown by the difference in their opercular movement.

Join now!

THE TEXTILE INDUSTRY:-

 

The textile printing in Sanganer town, district Jaipur (Rajasthan, India), is famous worldwide for its dyeing and printing industries. There are about 400 industries involved in textile printing processes which require approximately 4000 kl/day of good quality fresh water, which sometimes may go up to 5000 kl/day to meet market demands. 

WHAT AZO-DYES ARE:-

Azo compounds are compounds bearing the functional group R-N=N-R', in which R and R' can be either aryl or alkyl. The N=N group is called an Azo group. Azo compounds are generally seen to have vibrant colours, specially reds, oranges, and ...

This is a preview of the whole essay