Effect of surface-active agents on narrow-clawed crayfish Astacus leptodactylus

Panchyshnyy M.O., post-graduate student, department of applied biology, water bioresources and hunting

Kharkiv state zooveterynary akademia, Kharkiv

Key words: surface-active agents, mineral fertilizers, pesticides, crayfish, Astacus leptodactylus.

Actuality of the problem. From ancient times our reservoirs have been inhabited by different hydrobionts, one of them is narrow-clawed crayfish. With the development of civilization people began to use various agents that have become an indispensable part of our life. The above agents are able to come to the reservoirs and to exert negative influence both on the crayfish and on their environment. The effect of the above agents has not been sufficiently studied [1-4].

Materials and methods. Narrow-clawed crayfish Astacus leptodactylus (Eschscholz, 1823) was used in the experiment. The crayfish used in the experiment were of the same age and approximately of the same size (9-10 sm).

In each experiment the groups of crayfish that consisted of 10 females and 10 males were taken.

Before the experiment the crayfish were kept in similar conditions. They were placed in the aquariums at the temperature 18⁰ C.

During the experiment the installation having six aquariums, volume of each 100 liters, was used. The lighting was artificial, the lamps of the firm Luxel 20 watt were used. Fan ventilation was done by Atman pumps, power 500 l/hour.

Results. The aim of the first experiment was to determine the lethal dose (LD) when surface-active agents were used. For that the laundry detergent “Lotos” was used.

During the investigation the values that are given in the table below were determined (only lethal dose for crayfish have been shown). The recordings made during the experiment give the possibility to make the conclusion that the lethal dose for crayfish is 2,5 g/l of the laundry detergent “Lotos”. During the experiment it has been revealed that crayfish are able to withstand up to 2 mg/l of the laundry detergent diluted in the water, the behaviour of the crayfish does not differ from the normal one, during the experiment the crayfish continued eating though they constantly try to leave the container used in the experiment.

The aim of the second experiment was to determine the resistance of crayfish to insecticides including BI-58 new that is used in agronomy to protect plants from pests. On the basis of the analysis of the data received during the experiment the conclusion can be made that the lethal dose (LD) for crayfish is 0,05 ml/l insecticide BI-58 new. When the concentration is 0,04 ml/l the crayfish continue to live and eat though they in a very suppressed condition.

The aim of the third experiment was to determine the resistance of crayfish to fungicide Rydomil that is used to protect crops from fungal diseases. On the basis of the analysis of the data received during the experiment it was revealed that the lethal dose (LD) of fungicide Rydomil for crayfish is 5 g/l. When the concentration is 4 g/l the crayfish stay alive but a bit suppressed, eat and move in the container constantly trying to crawl out.

The aim of the fourth experiment was to determine threshold values of resistance of crayfish to herbicides diluted in water including the preparation Napalm that is used in agriculture to control weeds. On the basis of the analysis of the data received during the experiment the conclusion can be made that the lethal dose (LD) for crayfish is 0,08 g/l herbicide Napalm diluted in water. The dose 0,07 g/l of the diluted herbicide is not lethal the crayfish move on the bottom of the aquarium and eat badly.

The aim of the fifth experiment was to determine threshold values of resistance of crayfish to nitric fertilizers including ammoniac nitre. According to the data received the lethal dose of ammoniac nitre diluted in the water was 0,5 g/l. At the concentration of 0,4 g/l the crayfish stayed alive , they ate, actively move on the bottom.

The aim of the sixth experiment was to determine the threshold values of crayfish to phosphoric fertilizers diluted in water including superphosphate. It has been detected that crayfish die when the dose of suprhosphate is increased up to 0,06 g/l. At the dose of 0,5 g/l crayfish stay alive, eat though they constantly try to leave the aquarium under investigation.

The aim of the seventh experiment was to determine the threshold resistance of crayfish to potash fertilizers (potassium nitrate). The investigation showed that the lethal dose for the crayfish was 0.5 g/l potassium nitrate diluted in water. The crayfish died for 3 days. When the concentration was of 0,5 g/l crayfish stayed alive but they were very excited.

Table 1

Influence of surface-active agents and mineral fertilizers on narrow-clawed crayfish Astacus leptodactylus

Variant	Capacity	Composition, active agent	Concentration, %	Lethal dose (LD)	Period of death
Laundry detergent « Lotos’	g/l	Natrium sulphate, carbonates, silicates,water, phosphates, anionic surface-active agents, antiresorbent, optic bleach, air-hole	45	2,5	9 hours
Bi-58 new	ml/l	dimetoat	40	0,05	3 days
Rydomil	g/l	mancoceb	64	5,0	5 days
Napalm	ml/l	gliphosate	48	0,08	3 days
Ammoniac nitre	g/l	N	34,4	0,4	2 days
Superphosphate	g/l	P	40	0,6	4 days
Potassium nitrate	g/l	K	40	0,5	3 days

Conclusion

Visual observation of the narrow-clawed crayfish during the experiments showed that at the dose 2,0 g/l of the laundry detergent ‘Lotos » their behaviour was not different from the control one, they eat. The lethal dose for the above crayfish was 2,5 g per a liter of water. The insecticide under investigation (Bi-58 new) had the most negative influence on the narrow-clawed crayfish – the lethal dose for them was 0, 05 ml/l. The fungicide Rydomil at the dose of 5 g/l was also fatal for the crayfish. The herbicide Napalm (LD – 0, 08 ml/l) also turned to be active for the crayfish. Ammoniac nitre, superphosphate and potassium salt influenced the crayfish respectively : LD – 0,4 ; 0,6 ; 0,5 g/l.

Literature

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