FR2950782A1 - Luminous trap device for collecting larvae e.g. ichtyo plankton larvae, in research field of colonization of reefs e.g. artificial and natural reefs, has guiding unit movable between deployed position and closed position - Google Patents

Abstract

The trap device (1) has a collecting receptacle (10) collecting larvae and provided with a nozzle (110) and a cylindrical storage element (108). A light source (20) is placed opposite to the nozzle to attract the larvae when the light source emits light. The larvae move toward the receptacle when the light source does not emit light. A guiding unit (40) guides the larvae, and is movable between a deployed position and a closed position in which the guiding unit facilitates guidance and movement of the larvae toward the collecting receptacle. An independent claim is also included for a method for collecting larvae from a marine environment.

Description

GENERAL TECHNICAL FIELD

The present invention relates to a device and a method for collecting larvae, more particularly the planktonic zoo larvae in a marine environment. This invention finds particular application in the study of colonization of reefs, for example artificial and natural reefs, and more particularly in the study of colonization of ichthyoplankton.

STATE OF THE ART

The capture of larvae in the marine environment is an important issue for several areas such as the study of marine environments, the breeding of specific species, or any other applications.

A specific application is the study of the colonization of artificial reefs. It has been found that reefs, such as natural rocky areas, shipwrecks or any other submerged structure, promote the development of organisms in the marine environment, or attract marine life forms. The practice of immersing artificial reefs is known, and thus promotes the development of marine life forms. The study of these environments is important to ensure the maintenance of marine species, including the colonization of ichthyoplankton (larvae of fish and marine invertebrates).

In this document, larvae and / or post larvae of fish and marine invertebrates will be referred to as larvae. Several devices and methods have been developed to allow the collection of larvae, as described in the documents listed below. 130 FR 2825892 discloses a light trap for the collection of fish larvae, whose walls have a specific star shape and openings whose arrangement allows the entry of the larvae, while keeping them inside the light trap. .

Document FR 2809282 discloses a reef peak collector, comprising a device provided with luminous means overhanging collection means, this collector exploiting the fact that the larvae are attracted by the light (emitted by the light means in this example), but that in the absence of light, they tend to move towards a nearest object (in this case, the means of collection).

The document FR 2841742 describes a method and a system for collecting and rearing post-larvae of marine animals allowing only post-larvae to be collected, and to improve rearing conditions using specific containers and containers. . The collection system uses the same principle as that presented in document FR 2809282, according to which the larvae are attracted by the light and then tend to move towards a nearest object in the absence of light.

Figure 1 shows a light trap device 1 according to the state of the art. The light trap 1 comprises a receptacle 10, and a light source 20. The receptacle 10 as represented in FIG. 1 comprises: a tube 102, here whose section decreases according to the distance of the light source 20, a funnel 104 in order to facilitate the collection of the larvae 30 - anti-return means 106 of the larvae disposed inside the tube 102 - a storage element 108 in the continuity of the tube 102, which thus closes an end of the tube 102.

The light source 20 is associated with an activation buoy 204, the light source assembly 20 and the activation buoy 204 being connected to the receptacle 10 via connecting means 30.

The light source 20 serves to attract the larvae, which are naturally directed towards the light. Once the larvae have been attracted to the light source 20, it is extinguished, automatically or by means of a command. The larvae will then go to the receptacle 10; indeed, it appears to them as a dark mass in the water, and is then likened to a reef in which they can take refuge. They then pass through the funnel 104, then into the tube 102, and finally into the storage element 108 in which they are blocked by the anti-return means 106. The flared shape of the funnel 104 facilitates this movement of the larvae towards the inside of the receptacle 10.

As mentioned in the document FR 2841742, this device known from the state of the art is intended for the collection of larvae, excluding the following stages of growth of the organisms; thus, more developed organisms such as pelagic fish, which do not seek refuge in reefs, are not captured as long as they do not move towards the funnel once the bright means are extinguished.

However, the devices and methods presented in these documents are not entirely satisfactory, particularly as regards the collection of larvae.

Indeed, the devices and methods of the state of the art lead to an excessively high rate of larvae escaping collection devices. Especially in the case of the collection device described in FR 2841742, when the larvae are moving towards a nearest object in the absence of light, and therefore are supposed to be directed towards the collection means, a non negligible larvae is not collected by the collection means, and bypasses the collection means. PRESENTATION OF THE INVENTION

The invention proposes to overcome these drawbacks, and proposes a light trap device for the collection of larvae in the marine environment, comprising: a collection receptacle for the collection of larvae, comprising a mouth and a storage element; and a light source located opposite the mouth and adapted to attract the larvae when emitting light, the larvae moving towards the receptacle when the light source does not emit light; the device being characterized in that it further comprises means for guiding the larvae, movable between on the one hand an extended position, facilitating access to the light source 20 for the larvae, and on the other hand a position closed, facilitating the guidance and movement of the larvae to the receptacle.

According to specific embodiments, said device comprises one or more of the following features: - the guiding means include the light source when in the closed position; - The guide means comprise a thread extending peripherally to the mouth of the receptacle; The guide means comprise a rigid structure for stiffening the net and facilitating its actuation between the deployed position and the closed position; the net has stitches whose mesh gap diameter is between 2 and 10 mm; ; - The guide means are connected to an activation buoy, said activation buoy being removably attached to the light source; the collection receptacle has a decreasing section from the mouth towards the storage element; the collection receptacle comprises at least one anti-return means for the larvae.

The invention also proposes a method of collecting larvae in a marine environment, by means of a light trap device as defined above, the method being characterized in that it comprises the steps of: deployment of the guiding means in the deployed position - emitting light from at least one light source, so that the larvae are attracted to the light source, - moving the guide means in the closed position to encompass the light source, to guide the larvae attracted by the light source, - switching off the light source so that the larvae move towards the receptacle, - collecting, and storing the larvae in the receptacle.

According to a particular embodiment of this method, a connection is implemented between the guide means and an activation buoy, as well as a removable attachment between the activation buoy and the light source, characterized in that the step of moving the guide means to encompass the light source is caused by a step of separating the activation buoy, initially attached to the light source, which thus goes up to the surface, causing the movement of the light sources. guiding means.

PRESENTATION OF FIGURES

Other characteristics, objects and advantages of the invention will emerge from the description which follows, which is purely illustrative and nonlimiting, and which should be read with reference to the accompanying drawings, in which: FIG. 1, already commented on, presents a light trap device according to the state of the art. Figure 2 shows a light trap device provided with guide means in the deployed position. Figure 3 shows a light trap device provided with guiding means including the light means. Figure 4 shows a light trap device associated with flotation elements.

In all the figures, similar elements bear identical reference numerals.

DETAILED DESCRIPTION OF THE INVENTION FIGS. 2 and 3 show a possible embodiment of a light trap device 1 according to the invention.

The light trap 1 mainly comprises a receptacle 10, a light source 20, and guide means 40.

The receptacle 10 as shown in Figures 2 and 3 mainly comprises a tube 102 having a mouth 110, side walls 112 and a closed end embodying a storage element 108 larvae. The mouth allows the larvae to enter, and therefore has a suitable, relatively wide diameter Preferably, the tube 102 has a square or circular section, which decreases from the mouth 110 to the storage element 108 to facilitate movements of the larvae to this storage element 108. 6 The storage element 108, is in cylindrical form, directly in the continuity of the tube 102, and acts as a collector; it will trap the larvae to allow collection.

The light source 20 is connected to the receptacle 10 via connecting means 30. The light source 20 can alternate between two states; a state where it emits light in order to attract the larvae to them, and an extinct state where it does not emit light. The light source is also associated with an activation buoy 204, the structure and role of which will be described in more detail below.

The connecting means 30 are preferably rigid, for example rods, and hold the light source 20 at a constant distance from the receptacle 10 and in position. Several arrangements are possible for these connecting means 30; they are represented as crossed rods in Figures 1 to 3, but may consist of straight rods, not crossed. The light trap further comprises guide means 40 movable between an extended position (FIG. 2) allowing optimum gathering of the larvae so as not to block access to the light source 20 and a closed position (FIG. 3). allowing optimum guidance of the collected larvae to the receptacle 10, including the light source 20, and therefore a higher collection rate.

The guide means 40 are preferentially in the form of a net 410, the operation of which is described in more detail later in this description.

The guiding means 40 are preferentially in the form of a net 410 movable between an extended position (FIG. 2) allowing an optimal gathering of the larvae around the light source, so as not to block access to the light source. 20, and a closed position (Figure 3) for optimal guidance of the collected larvae, including the light source 20.

According to a particular embodiment, the net 410 has a mesh gap of between 2 and 10 millimeters, typically 3 millimeters or 5 millimeters. The specifications of the net 410, for example the mesh, make it possible to adapt the device according to the species to be studied.

The thread 410 has an internal periphery 412 which cooperates with the wall 112 of the tube 102, and preferably extending peripherally to the mouth 110, and an outer periphery 414 defining the maximum span of the thread 410.

The guide means 40 also comprise a rigid structure 420, between the inner periphery 412 and the outer periphery 414, for example aluminum rods. This rigid structure 420 stiffens the net 410, to maintain it with a satisfactory span, preferably maximum in the deployed position. Advantageously, the rigid structure 420 makes it possible to move the net 410 between the deployed position and the closed position, as will be described in more detail below.

The links 430 connect the guide means 40 and the activation buoy 204, which allows mobility between the deployed position and the closed position, depending on the position of the activation buoy 204 relative to the receptacle 10, and therefore in fact with respect to the light source 20, since the light source 20 and the receptacle 10 are fixed relative to one another due to the connecting means 30.

The operation of the device is as follows.

Initially, the device is immersed in a configuration shown in Figure 2. As shown in Figure 4, the device is connected to buoyancy elements, for example a surface buoy 50, which is sized to remain on the surface of the water. 'water. The device is connected to this buoy 50 by a guide cable 510, said guide cable 410 being for example connected to the activation buoy 204 or to the light source 20 by means of a guide link 520. Several of these devices can be associated in chain, connected to one or more buoys to expand the capture area, each device can be immersed at various depths allowing more comprehensive studies.

In FIG. 2, the guiding means 40 are represented in the deployed position, which confers on them in the embodiment shown a maximum span (all located in the same plane, substantially horizontal in a direction of normal use of the device), thus making it possible not to hinder access to the light source 20, while allowing to attract and keep larvae by its large scale.

In this configuration, the light source 20 serves to attract the larvae, which naturally move towards the light sources.

After a certain time (which may vary between a few hours and ten hours), the configuration of FIG. 3 is carried out, in which the guiding means 40 are in the closed position, including the light source 20.

Once the guide means 40 are in the closed position, the light source 20 is extinguished, the switching off of the light source can be controlled by the user, or automatic.

The passage from the deployed position of the guide means 40 shown in FIG. 2 to the position encompassing the light source 20 shown in FIG. 3 is effected by the raising of the activation buoy 204 relative to the receptacle 10. To do this, the activation buoy 204 is associated with the light source 20, for example by magnetization; the light source 20 is then housed in a metal casing, and the activation buoy 204 is kept magnetized to this metal casing by applying an electric charge to generate a magnetic attraction. Other modes of attachment are possible; the activation buoy 204 may for example consist of a tank initially filled with water, in which is injected air to cause its rise to the surface. The activation buoy 204 may also be associated with any other element of the device 1, preferably at least at the height of the light source 20.

Activation buoy 204 may take a number of forms; for example an annular buoy whose inner ring is magnetized, or any magnetized form above the housing of the light source 20.

Concomitantly with the extinction of the luminous means 102, the electric charge maintaining the buoy would be canceled or inverted, causing the buoy 204 to rise up along the guide cable, thus causing the raising of the guide means 40 due to the connections 430. This cancellation or inversion of the load can be performed automatically via an electronic circuit board, or controlled by a user, which is of interest to diversify collections.

This device thus makes it possible to increase the efficiency of the capture by limiting the escape of the animals outside the receptacle 10; the guiding means 40 make it possible to cover a larger volume, and the fact that their ascent does not occur for example until substantially before the extinction of the light source 20 makes it possible not to block access to this light source 20 when lit, which would reduce the efficiency of capture.

Advantageously, the activation buoy 204 also makes it possible to maintain a vertical position of the device, which makes it possible, after use, to pull the light trap out of the water without the risk of losing the larvae contained in the receptacle 10.

Advantageously, the tube 102 comprises anti-return means 106 of the larvae disposed on the inner surface of its walls 112.

The anti-return means 106 are in the form of annular lips to cooperate with the inner surface of the walls of the tube 102, extending on the one hand from the wall towards the center of the tube 102 and on the other hand towards the element storage 108.

Typically, the anti-return means 106 are of the type of anti-return means used in the crustacean traps, such as crab or lobster traps.

The receptacle 10 may comprise several anti-return means 106 superimposed as seen in Figures 2 and 3. To limit the cost of the device, it is possible to use a shrimp basket instead of the receptacle 10. Such baskets shrimp are well known, and used by professional fishermen.

Claims (9)

Revendications1. A light trap device (1) for collecting larvae in a marine environment, comprising - a collection receptacle (10) for larval collection, having a mouth (110) and a storage element (108); and a light source (20) located opposite the mouth (110) and adapted to attract the larvae when it emits light, the larvae moving towards the receptacle (10) when the light source (20) does not emit light; the device being characterized in that it further comprises means (40) for guiding the larvae, movable between on the one hand a deployed position, facilitating access to the light source (20) for the larvae, and on the other hand a closed position, facilitating the guidance and movement of the larvae to the receptacle (10). 2. Device according to claim 1, characterized in that the guide means (40) include the light source (20) when in the closed position. 3. Device according to one of the preceding claims, wherein the guide means (40) comprise a thread (110) extending peripherally to the mouth (110) of the receptacle (10). 4. Device according to the preceding claim, wherein the guide means (40) comprise a rigid structure (420) for stiffening the thread (110) and facilitate actuation between the deployed position and the closed position. 5. Device according to one of claims 2 or 3, wherein said net (410) has mesh whose mesh gap diameter is between 2 and 10 mm. 6. Device according to one of the preceding claims, wherein the guide means (40) are connected to an activation buoy (204), said activation buoy being removably attached to the light source (20). . 7. Device according to one of the preceding claims, characterized in that said collection receptacle (10) has a decreasing section of the mouth (110) to the storage element (108). 8. Device according to one of the preceding claims, characterized in that the receptacle (10) for collecting comprises at least one anti-return means (106) larvae. 9. A method of collecting larvae in a marine environment, by means of a light trap device as defined in one of claims 1 to 8, the method being characterized in that it comprises the steps of: - deployment of the means of guiding in the deployed position, - emitting light from at least one light source, so that the larvae are attracted to the light source, - moving the guiding means in the closed position to encompass the light source, for guiding the larvae attracted by the light source, - switching off the light source so that the larvae move towards the receptacle, - collecting, and storage of the larvae in the receptacle.1O.A larvae collection method according to the preceding claim a connection between the guide means and an activation buoy, and a removable attachment between the activation buoy and the light source, characterized in that the step of moving the guiding means for encompassing the light source is caused by a step of separating the activation buoy, initially attached to the light source, and thus back to the surface, causing the displacement of the guide means.