Biological specifics of invasive species gastropoda Melanoides tuberculata

UDC 594.3

A. Klimchuk
Dnipropetrovsk State Agrarian and Economic University, Dnipropetrovsk, Ukraine

A. Клімчук
Дніпропетровський державний аграрно-економічний університет, Дніпропетровськ, Україна,

With increasing human impact on animal and plant ecosystems, biological invasions begin to disrupt their stability and cause qualitative and quantitative changes. The phenomenal success of invasive plant and animal species is a mystery, which is often studied from an ecological point of view. In Ukraine extends the local introduction of aquarium species of mollusks into open natural and artificial reservoirs. Quite often happens discharge of water which contains different organisms, including alien organisms from aquariums in surface water.

These organisms usually have tropical and subtropical origin and can’t survive in the severe environment of temperate climate. However, some heat-loving species can survive in artificial reservoirs of power stations in which there is a dropping of heated water, or in the waters of the most southern regions of Ukraine. Melanoides tuberculata became one of the new and dangerous invasive species. This is a small gastropods African’s origin, which survives in quite high temperatures. Its feature is the ability to quickly master new territory, in particular was noted its widespread distribution in natural waters of Brazil. Also, during the last 10–15 years M. tuberculata settled in warm cooling ponds of nuclear power plants in Ukraine. Due to the high reproductive ability the species rapidly propagate and clog the filters and the drains at the plant station and cause bio-fouling that can cause accidents. Consequently, there is an urgent need to develop effective and economically justified methods of controlling this species.

The literature describes various methods of control bio-fouling on the hydraulic structures of nuclear power station. One of the most optimal methods is biological. For this control are used species that are natural enemies of shellfish. In particular, the positive results are getting from settling ponds by species such as black carp Mylopharyngodon piceus. This species belongs to fishes that eat mollusks and can successfully control the mollusks’ populations and as the result to solve the problem of mass reproduction and danger for the waterworks. There is an evidence of its successful use to control the bivalves zebra mussel.

Analyzing the behavior and biological characteristics of the species M. tuberculata was found that the mollusk eats detritus (remains of dead plants and other cankered organic), therefore most of the time it interrupts the sandy bottom of pounds searching for food. Mollusk comes out of the sand mostly through adverse conditions such as acidification of bottom, poor water’s quality, lack of food or dissolved in water oxygen. This creates the problems of its destruction, because for fish it is difficult to eat mollusk buried in the sand. Considering this, was performed an experiment, the aim of which was to determinate the depth of mollusks digging in sandy soil.

To determinate the depth of M. tuberculata digging in the soil were purchased 7 adults, who were held in a private aquarium and placing in a glass with capacity of 2 liters. Water and sand were taken from the cooling pounds of Zaporozhian NPP. On the glass was drawn a measuring scale with length 9 cm, with a division value 1 cm. The initial level of sand was 8 cm. To determine the depth of mollusks digging, first of all it was necessary to take away the water without disturbing mollusks buried in the sand. For this purpose was used a special selection pipette. The water was gradually taken away to an another container. Then, using a special blade, sand was taken away by layers of 1 cm. in the tray. After the extraction of the sand it was washed and looked over, searching the shells of under study mollusks.

In consequence of the experiment, in the upper layer of sand was found five individuals of mollusks (71 % of all individuals). The last 2 individuals (29 % of all individuals) were found at a depth less than 5 cm.

The results of the experiment make it possible to assume that the biological way of controlling the invasive species M. tuberculata can be effective, because most of the individuals were in the upper layer of sandy soil that is accessible to fishes which eat mollusks.

Zoocenosis — 2015
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