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July 31, 2017

Features of Barents Sea mussels behavior under laboratory conditions

Introduction

Although the available data on large stocks of mussels and made successful attempts to cultivation, fishing and mariculture mussel Murman not received to date significant development. Undoubtedly, one of the reasons for this situation is the lack of research into the biology and ecology of the Barents Sea mussels and lack of proper scientific justification of their fisheries and aquaculture in the Arctic. The research results are presented in mussels Murman very few papers (see. E.g., the review ). In studied the activity of mussels on such parameter as the URS (level of disclosure leaflets). However, URS registration is performed only once per day. The resulting series, too, is clearly insufficient – the maximum length of a number is not more than 13 values.

The methodology of the experiments

In our experiments, the method has been applied automatic registration. As a criterion of life mollusks used their motor activity, i.e., URS. Join the movement mussels sashes carried through the assembly kinematics and      reducer connecting the latter to the ADC (analog-to-digital converter) with the output data to a computer

The design of the experimental setup

In earlier experiments, the Registrar used a high-speed multi-channel data recorder H-338 4P. Continuous registration URS allows you to explore not only the per diem, but also short-period motion valves. Resolution measurements varied from one second to one minute. Daily three-day recording and mussels flaps movements are the starting material for the behavior analysis (Figure 2), and periodic changes of shellfish activity. In special experiments (feeding, mechanical stimuli) used two parallel shellfish.

The initial series of mussels activity were obtained by conducting experiments in an aquarium with sea water, where the salinity was 36 ‰, and the temperature of 14 ° C. For the analysis were selected the data obtained in the period from 10 to 14 April 2008, on May 7, from 8 to 10 May 2009. Resolution of the first and second series of measurements – 1 minute, depending on the timing of observations, resolution follows a series of 1 second. When the experiments were determined by factors in addition to the motion detection mussels flaps, which could affect the motor function, namely atmospheric pressure, types of pressure systems over the experimental area, geomagnetic disturbances (GMV). The role of atmospheric conditions can directly influence the behavior of the mussels, which is quite natural, but in a number of processes, Agrophysical generated electromagnetic fields of extremely low frequency. Reported atmospheric factors were determined by the weather map from the website and used in the analysis of the experimental data. To analyze the impact of geomagnetic disturbances (GMV) on the flaps motion data used Sodanklyul Observatory (Finland)

All experiments described below were carried out at constant external meteorological and geophysical factors, capable, according to the authors, to somehow skew the results.

Methods of data processing

To process the data using standard Mesosaur packages, Excel. To calculate the fractal dimension of the original package is used Herst. The fractal dimension is known to be characterized by deterministic process (Hurst coefficient greater than 0.5) or chaotic (respectively, the ratio is less than 0.5).

Rows passed through a bandpass filter Potter at which eliminates sampling noise and trend components. To isolate the activity of long components used polynomial or median smoothing.

Biorythmics: Results and discussion

Periodogram calculated motor activity of mussels (flaps movement) revealed the presence of distinct peaks (Figure 2). The main important spectral peaks were 10, 8, 6, 4 and 2 hour. This rather unexpected result, especially, the maximum period that would seem to be even semi-diurnal and semi-diurnal tidal oscillations correspond to sea level (12.4 hours). Period 6:00 is quite clear (about quarter diurnal tide), the rest of the period, apparently due to physiological factors.

Motor activity of mussels (movement flaps) for multi day of the experiment (4 hours, resolution 1 min).

Expected day period, possibly related to peak 8 hours (3 times a day). Although it should be noted that in experiments of longer duration conducted in a year, the period of 24 hours was detected. However, these periods of activity still does not correspond to the periods of tidal processes in the Barents Sea. Perhaps this is due to the content of shellfish in a laboratory basin, where it is not fully complied with the conditions, the corresponding natural.

This discrepancy biorythmic diurnal and semidiurnal tides periods detected in crabs, acclimatized in the Barents Sea. Typical periods of their rhythm, the following: 16, 10, 8, 6 hours. Apparently, such a coincidence of spectral features is not accidental.

The behavior of the two mussels placed in the aquarium close to each other, turned almost simultaneously

Synchronous behavior of two mussels in a calm state. Recording on a multichannel recorder. Time – minutes (long division).

The behavior of the two mussels in the excited state (logic 1 min).

All this is again an unexpected result, since any of the bodies of identified experimentally, mussels there. Some bivalves, as we know, there are some underdeveloped vestiges on the edges of the mantle. Apparently, there is some other information from one channel to another mussel.

When registering through the ADC and PC with a readability of 1 min revealed a similar excess of short-period synchronism with observed some differences in the movement of the flaps, which are inconspicuous in larger discreteness, in particular mussel 2 appears to be more mobile.

The behavior of mussels when exposed to external factors

Very interesting behavior of two mussels by mechanical stimulation. This irritation produced thin glass laboratory stick-probe descends vertically from the top, so as not to cause vibrations in the water. Glass was used in order to avoid galvanic electrical effects possible, such as a metal probe.

During stimulation, one of the mussels again obtained an unexpected result – the second mussel also alters opening flaps

Level two flaps mussels disclosure by mechanical stimulation

Irritation acted in 0:26:20 minutes and only one mussel 2. As can be seen from the graph, the reaction is immediate and after 10 seconds at the level of the valves opening mussels decreases. Maximum reaction reaches 43%. Also interesting is the fact that mussel number 1 one minute later responded to the stimulus. This suggests that they respond not only to a particular stimulus, but they occur like chain reaction (one influence to another mussel, untouched).

First, the “pristine” mussel opening the valves increases, after leveling at around 62% both mussels almost simultaneously reduce the URS, but after about 4 minutes mussel 1 like “lose interest” in mussels 2, and again begins to reveal sash.

It turns out that between the mussels again, there is some information link. The mechanism of this connection is unknown.

We tested the hypothesis that the cause of connection are possible vestiges of eyes on the mantle edges, like other bivalves. Therefore, in these experiments, one of the mussels was isolated opaque matte screen, which exclude direct communication as visual and acoustomechanical (water waves).

The screen was designed as a round plastic container with a diameter of about 30 cm, mounted on a flexible substrate. The container of the presence of walls and bottom acoustomechanical had no connection with the rest of the pool water, which was uninsulated mussel. Matte plastic was taken to both the mussels to maintain the same illumination from an external source. The water inside the container was filled with the same characteristics (salinity, salt content, temperature, pH, dissolved oxygen) as in the experimental pool.

The reaction of the two mussels, one of which is insulated, to mechanical stimulation.

The “untouched” mussels 2 (gray curve), the reaction is usually – the level of the valves opening is reduced. However, the reaction of 1 mussels (black curve), which has not been touched, the opposite of what is shown in Figure 5, – here it opens the leaf.

To eliminate any subjectivity in the assessments, the correlation coefficients were calculated for different situations.

The correlation coefficients of activity of two mussels

Significant and very high correlation coefficients cannot be explained within the framework of the idea of having known and sufficiently effective information transfer bodies to each other. There is some other mechanism. It can hardly come, as a surprise, since the mussel colonies, apparently, cannot possibly be direct (visual or acoustomechanical) connection.

Also unexpected signs of correlation coefficients. During stimulation of only one high coefficients of mussels and negative at the same time in roughly equivalent conditions, (see. E.g., the bottom line of the table) are positive coefficients are high. All this does not yet have an explanation.

It should be added that further experiments were carried out with feeding, which showed similar results. Before mussels to eat in the pool water level was lowered to the water in the container is not in contact with water from the rest of the pool. Thus, it excluded chemoreception. It carries food isolated mussels. Delayed reaction in the second mussels (uninsulated) was 3-4 seconds. The correlation coefficient of activity of both mussels at a time when isolated clam ate, reached values of 0,6 ÷ 0,7.

Determinacy behavior

Evaluation of determinism by calculating Hurst coefficient. H directly connected, as is known, the so-called fractal dimension D () with this factor. Both are characterized by deterministic behavior (H> 0,5) or chaos in the behavior (H <0,5). Method of calculation is described.

It follows from these results, the mussels behavior rigidly determined (Hurst coefficient substantially greater than 0.5), and is determined by internal physiological needs. Two discharge point (approximately 06.10ch. 8.01.2010 and 19.42 h. For the same day) does not lead to chaos behavior).

Similar results were also obtained for the other terms of long experiments.

Conclusions

  1. Different versions of the behavior of the mussels in a laboratory experiments are not random. This behavior is determined and apparently defined by some yet unknown (or poorly known) physiological or geophysical factors.
  2. Biorhythmic motor activity of small target approximately corresponds to the periods of tidal processes in the Barents Sea. Perhaps this is related to the content of shellfish in the laboratory.
  3. The effect of mussels on each other when the joint arrangement is in an outdoor setting, and in isolation from one mussel opaque screen, which eliminates the visual and acoustomechanical connection. High correlation coefficients are forced to assume the existence of some other physical mechanisms for communication, not due to rudimentary organs of sight or highly sensitive to fluctuations in water.

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