Abstract:
A device for colonizing and harvesting marine hardground animals in an underwater region of a ground-based offshore edifice includes at least one rail device configured to extend vertically on the offshore edifice along a height of the underwater region to above a waterline. The device also includes a netting array including a habitat carriage having a habitat and trapping basket that is adapted to contain the hardground animals. A lifting device is configured to move the netting array along the at least one rail device. Additionally, the device includes a scavenging carriage including a basic unit and a running unit that is configured to detachably couple the scavenging carriage with the at least one rail device so as to be movable thereon. The scavenging carriage is configured to detachably couple with the habitat carriage and the lifting device.

Description:
CROSS-REFERENCE TO PRIOR APPLICATIONS 
       [0001]    Priority is claimed to German Patent Application No. DE 10 2009 058 278.9, filed Dec. 13, 2009, the entire disclosure of which is hereby incorporated by reference herein. 
       FIELD 
       [0002]    The invention relates to a device for colonizing and harvesting marine hardground animals in the underwater region of ground-based offshore edifices. 
       BACKGROUND 
       [0003]    Marine edifices are suitable for colonization by hardground animal species. This can be observed especially clearly in areas marked by the absence of natural colonization structures, such as in the softground regions of the southern North Sea. The surfaces of the edifices, such as pylons of wind power plants, are here used as colonizing surfaces by the reef animals. In order to augment such reef animals, various types of so-called “artificial reefs” are assembled or submerged into the sea worldwide. Net fishing with draw nets and beam trawl nets is difficult or impossible in the immediate proximity to marine edifices. In addition, it is not sustainable, and can quickly lead to overfishing. Marine hardground animals, such as lobsters, crabs, snails, mollusks and several types of fish, have previously been caught in inaccessible areas or not readily fishable sea floors using baited traps, such as lobster creels. However, baited traps have to be brought in again a short time after set up. Therefore, they cannot be left on site for an indeterminate time, for example during inclement weather, without jeopardizing the catch. In addition, such traps may get caught on parts of edifices or be shifted into impermissible positions on foundation structures on the sea floor as the result of currents and wave dynamics. As a result, they cannot be placed precisely in the most favorable positions on the foundation structures. In addition, such traps themselves do not provide an attractive colonization habitat. Further, the traps must be specially marked with lines and buoys, which can tear away when used on offshore edifices or lead to other problems. 
         [0004]    U.S. Pat. No. 6,186,702 describes a habitat and trapping device that can be used for lobsters, for example, a so called “artificial reef”, which is simply released onto the sea floor and retrieved again when necessary. U.S. Pat. No. 5,596,947 describes larger holding boxes, which are lowered from inclined rope guides from a special platform and hauled in again. Vertically submergible stacked habitat and harvesting boxes are described in WO 2004/075633 A1. 
         [0005]    DE 203 10 089 U1 describes a netting array in the area of a wind power plant pylon for colonizing and harvesting hardground animals, which can be lowered and retrieved by means of a cable winch as the lifting device. The netting array is here designed as a basket that is relatively unattractive to the hardground animals and which is simply lowered into the water or placed on the sea floor. This netting array is positioned as desired by means of a rail system, which partially or completely horizontally envelops the pylon in a radial plane, and has hooked into it a framework for the cable winch. Therefore, a horizontally running rail system is known for positioning a netting array as desired around the periphery of the pylon. The netting array is lowered and retrieved exclusively via the cable winch, unguided in the free sea currents, thereby creating a strong dependency here. The settling netting array can here threateningly get into the operating area of the edifice or any service facilities on hand. The net fishing array cannot be precisely positioned. Additionally, U.S. 2006/0170221 A1 for the same object describes to lower and retrieve a special, detachable catching substrate via an electrical cable winch directly on the pylon, so that the pylon itself here provides a kind of guide. However, the latter is not supported by securing elements, so that sea currents can here also be disruptive, and impede the harvesting process. 
         [0006]    EP 1 466 523 A2 describes an extremely complicated design for bilaterally harvesting vertical netting substrates colonized by mollusks, for example. Two harvesting roller bands are here lowered on either side of the netting substrate on a vertical rail system. The band movement transports the colonized mollusks toward the water surface. The vertical rail system with the harvesting roller bands is secured to the side of a ship correspondingly positioned over the substrate. Lastly, described in GB 2 270 664 A is another vertical rail system with a moving carriage for the attachment of devices, which is arranged downward from the water line in the underwater region of a column of a footbridge. A boat can be connected with the rail system by means of a fender, so that depth-induced fluctuations in the boat level can be offset by vertically moving the fender on the rail system. 
       SUMMARY 
       [0007]    In an embodiment, the present invention provides a device for colonizing and harvesting marine hardground animals in an underwater region of a ground-based offshore edifice. The device includes at least one rail device that is configured to extend vertically on the offshore edifice along a height of the underwater region to above a waterline. The device also includes a netting array including a habitat carriage having a habitat and trapping basket that is adapted to contain the hardground animals. A lifting device is configured to move the netting array along the at least one rail device. Additionally, the device includes a scavenging carriage including a basic unit and a running unit that is configured to detachably couple the scavenging carriage with the at least one rail device so as to be movable thereon. The scavenging carriage is configured to detachably couple with the habitat carriage and the lifting device. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0008]    The device according to the invention for colonizing and harvesting marine hardground animals in the underwater region of ground-based offshore edifices with at least one rail device for accommodating in whatever location desired a netting array for the hardground animals that can be vertically moved by means of a lifting device will be described in even greater detail below based on the diagrammatic, exemplary figures not drawn to scale. The invention is not limited to the exemplary embodiments. Other features and advantages of various embodiments of the device according to the present invention will become apparent by reading the following detailed description with reference to the attached drawings which illustrate the following: 
           [0009]      FIG. 1  is a side view of the scavenging carriage; 
           [0010]      FIG. 2  is a cross section of the scavenging carriage; 
           [0011]      FIG. 3  is a side view of the submerged habitat carriage with opened habitat and trapping flap; 
           [0012]      FIG. 4  is a perspective view of the submerged habitat carriage with opened habitat and trapping flap; and 
           [0013]      FIG. 5  is a side view of the habitat carriage with closed habitat and trapping flap during retrieval. 
       
    
    
     DETAILED DESCRIPTION 
       [0014]    In an embodiment, the present invention provides a device that enables an especially precise and reliable deployment and retrieval of a netting array, without having to depend on the prevailing currents in proximity to the edifice or disruptively interfere in the operational area of the edifice. At the same time, however, the device is easy and reliable to access and operate. 
         [0015]    The device according to an embodiment of the present invention exhibits at least one vertically arranged rail device, which extends over the height of the underwater region until above the waterline. Above the waterline, the device can be easily serviced with “dry feet” from a boat or a platform secured to the pylon, i.e., loaded and unloaded. The rail device is loaded with a habitat carriage having a habitat and trapping basket as the netting array, and temporarily with a scavenging carriage. Both the habitat carriage and scavenging carriage each have a base unit and at least one running unit that allows them to be detachably coupled with and travel on the rail system. In addition, the carriages have means with which they can be detachably coupled to each other. Finally, the scavenging carriage can be detachably coupled with the lifting device. The invention uses the direct proximity to the edifice, which results in a particularly good utilization and enrichment of the existing aufwuchs. In addition, arranging the device directly on the edifice (installation depth of the rail device in a range of 20 cm) does not significantly increase its flow resistance, and the working area is not impaired. Constructing the rail device in a fixed location makes it possible to deploy, store and retrieve the carriages in an especially location-precise way. 
         [0016]    In an embodiment, the invention provides at least one vertically running rail device in the entire underwater region of a pylon, for example, on which the habitat carriage can be lowered to the seafloor in a precisely defined way without being influenced by arising currents. To this end, the running units of the habitat carriage are coupled into the rail system via the end of the rails or recesses in the rails above the waterline and simply released. The weight of the habitat carriage causes it to drift down to the seafloor along the rails. On the seafloor, the habitat carriage can be left however long desired in the rail system and is there colonized by hardground animals. The invention prevents the habitat carriage from drifting away in the current or wave dynamics or the operational area of the offshore edifice from becoming impaired by protruding or outwardly drifting parts or ropes. The habitat carriage is scavenged at any time with the use of the scavenging carriage. For this purpose, the running units of the latter are also coupled above the waterline with the rail device, but also with the lifting device. The scavenging carriage is subsequently released, and drifts downward toward the seafloor, wherein the lifting device correspondingly slackens the rope so as not to impede submersion. While sinking, the scavenging carriage then encounters the already submersed habitat carriage, and is coupled securely, yet detachably, thereto by means of a corresponding device. The aggregate comprised of the scavenging carriage and habitat carriage is then retrieved together via the lifting device. The aggregate can here be pulled so far out of the water that the habitat carriage under the scavenging carriage also lies above the waterline, and again accommodated in a “dry feet” zone, i.e., decoupled from the rail device or collected. 
         [0017]    The device according to an embodiment of the present invention acts as an auxiliary habitat at offshore edifices, such as the columns of wind power plants. At the same time, it serves as a trapping and harvesting device with a fixed location, which can be used for commercial purposes without laying bait in these agglomeration points for fishable types of animals. The device can be used to fish for all animals that settle in the additionally created habitat. Further, depending on the design of the device, animals encountered can also be caught in direct proximity to the device, for example in the gap between the device and edifice, or on the ground near the device. The edifices already existing or awaiting construction can also be subjected to secondary commercial use, which as a rule often lends considerable support to cost-intensive conversion of the primary form of economic output, frequently power production (multifunctional use of offshore edifices). The animals to be harvested live on the additional substrate artificially created with the invention, and thus are not encountered in only isolated numbers in softground regions where offshore edifices are generally not erected. Only the excess number of animals in the partial area of the underwater structure are harvested. The offshore edifices here have a natural fouling community that provides sufficient nutrition for the colonizing harvest animals. While they do not have to be additionally fed, they can be. The objective of partial fishing approach and stabile conditions relative to nutrition and living space in the fished area combined with a sustained cultivation concept is to foster a stable recruitment of new animal species. The additional colonization surface of the habitat and trapping basket of the habitat carriage here serves as a colonizing area for both the animals being harvested and their nutrition or nutritional animals. Above all the ability to precisely remove the device here ensures a sustained cultivation and care relative to the local animal stock. In addition, the device can be used to protect the species and nature, provided that fishing (harvesting) only takes place on a limited basis or is even abandoned completely after its removal. 
         [0018]    No separate edifice has to be erected for installing the device according to an embodiment of the invention. Prior to their offshore erection in the sea, the planned edifices must only be equipped with the simplest of accessories, for example, in the form of a rail device with an extremely simple design, that does not affect the load-bearing capacity. The rail device and scavenging carriage can here also be beneficially used for components other than for the netting array in an embodiment of the present invention, for example for submerging remote-controlled cameras, cleaning brushes, lifting systems, diver equipment or other loads or materials, during which a crane system built into the edifice can be used. Finally, the rail device can also be used as a climbing aid for divers. As a result, the invention offers a complete habitat and trap solution that can be used to especially beneficial effect for the commercial care and propagation of economically useful animals and their sustained harvesting in preferably large offshore edifice groups, such as wind parks. However, it could also make good sense in some cases to erect separate edifices for the device according to an embodiment of the present invention, or retrofit already existing offshore edifices with the rail device. The rail-carriage system can further be used for the upkeep, maintenance and inspection of offshore edifices. The advantage is that only one or a few scavenging carriages need to be held in reserve, so that all rails are used, and a wide variety of tasks can be implemented. 
         [0019]    The netting array is deployed precisely to the location by means of the habitat carriage and rail device, which is vertically arranged on the foundation structure of the offshore edifice. Only a single vertical rail system can here be provided on the periphery of the edifice. In particular in the case of round edifices, such as wind power pylons, several vertical rail devices (and correspondingly more habitat carriages, but also just one scavenging carriage used to scavenge all habitat carriage) can also be situated around the periphery. For example, four paired diametrically opposed rail devices can be provided. Even when several rail devices are arranged closely together, deploying the habitat and trapping baskets to the precise location via the habitat carriages on the rail devices reliably ensures that the individual components will not impede or impair each other. 
         [0020]    For example, the basic unit of the habitat carriage on the rail system is introduced from a ship proceeding from the upper end of the rail device or via corresponding recesses in the underwater region of the rail device. It is here advantageous that the rail device be equipped with a T-shaped guide rail, and the running unit of the habitat carriage and scavenging carriage be furnished with a T-shaped guide groove. For example, the T-shaped guide rail can here be securely bolted to the edifice in a simple manner, or simply be welded on as a steel rail in an advantageous embodiment. The T-shaped guide groove of the running unit engage via the T-shaped guide rail, thereby reliably ensuring guidance in a vertical (toward the rails) and horizontal (orthogonal to the rail) direction. To ensure that the T-shaped guide groove effectively glides over the T-shaped guide rail, the T-shaped guide groove can additionally be provided with running rollers, which roll onto the T-shaped guide rail from behind. To prevent the habitat carriage from tipping over sideways on the T-shaped guide rail, the habitat carriages and scavenging carriages are provided with spacers for purposes of lateral stabilization. The spacers support the habitat and scavenging carriage directly against the edifice to the right and left of the vertical guide rail. 
         [0021]    The T-shaped design of the guide rail and guide groove already provides a reliable safeguard that prevents the carriage from lifting off of the rail device during submersion or retrieval. To reliably prevent the carriages from tilting in the horizontal direction due to a slight (buoyancy or current induced) lifting of the carriage, it would be advantageous to provide at least one guide roller that abuts the offshore edifice and weights that exert a force acting horizontally on the offshore edifice (secured via a rotatably mounted lever arrangement), at least on the scavenging carriage. The weights press the scavenging carriage against the edifice via the lever arrangement and a guide roller. In addition, the roller design allows the scavenging carriage to easily traverse the edifice. Since the scavenging carriage is also lowered exclusively by downward drift, this process can be accelerated with additional weights on the scavenging carriage with a force acting vertically downward, thereby enabling an especially quick scavenging of the habitat carriage. All aforementioned measures can be performed in equal measure on the habitat carriage as well. The latter can have an additional, weight-assisted guidance and additional downward drift weights. 
         [0022]    The lower end of the scavenging carriage preferably has a reception flange. This flange can accommodate various tools, which perform different functions. For example, an underwater video camera can be added when not using the scavenging carriage to retrieve the habitat carriage, but to observe the animals underwater or inspect the edifice. In order to retrieve the habitat carriage, it is preferred to immovably arrange a scavenging bracket on the reception flange of the scavenging carriage, and a scavenging mandrel on the upper end of the habitat carriage. The scavenging bracket latches securely, but detachably, in the scavenging mandrel of the habitat carriage as the scavenging carriage is vertically submerged, thereby also taking along the habitat carriage when retrieving the scavenging carriage by means of the lifting device. The lifting device for the scavenging carriage can preferably be a manually operated or electrical cable winch, which is secured either directly to the offshore edifice, or to a working platform or a service ship. 
         [0023]    As stated further above, the habitat carriage is used to enlarge the habitat for hardground animals, only a few if any of which would otherwise be found in the softground regions of most offshore edifices. To maximize this expansion, it is advantageous to equip the habitat and trapping basket of the habitat carriage with a foldout habitat and trapping flap. The habitat and trapping basket can already be submerged with the habitat and trapping flap open. The habitat and trapping flap then is immersed even further in the lower position of the trapping basket, and sits on the seafloor at an angle, or lies horizontally on the seafloor. The direct contact between the habitat and trapping flap and the seafloor makes it especially easy for the animals walking around down there to reach the habitat and trapping flap and habitat and trapping basket, especially lobsters and crabs. In order to maximize the harvest of these animals when hauling in the trapping basket or habitat carriage, it makes sense to close the habitat and trapping flap beforehand. To this end, the device according to an embodiment of the present invention can be provided with another scavenging mandrel detachably arranged on a reception pin on the scavenging mandrel on the habitat carriage, and at least one flap rope, one end of which is secured to the upper end of the habitat and trapping flap. To improve closure, two spaced apart flap ropes can also be provided at the upper end of the habitat and trapping flap. The other end of each flap rope is secured to the additional scavenging mandrel, and is guided through a correspondingly arranged eyelet at the upper end of the habitat carriage. When the scavenging bracket on the scavenging carriage now latches into the additional scavenging mandrel, the latter is pulled off while retrieving the reception pin, pulling the flap rope up through the eyelets. The eyelets are here situated on the habitat and trapping flap in such a way that no tilting moment arises while retrieving the habitat carriage. During retrieval, the habitat and trapping flap is closed, and the closed habitat carriage is pulled up on the flap rope. In principle, this type of closure mechanism can also only be implemented with a detachable scavenging mandrel sitting on a simple reception pin. However, the additional scavenging mandrel provides for a dual scavenging option for the habitat carriage. For example, if the additional scavenging mandrel slips off the scavenging bracket or was removed owing to outside influences (e.g., objects drifting to and fro), or the flap ropes are torn, the habitat flap does open again, but the entire habitat carriage can still be reliably scavenged by now again latching the scavenging bracket directly onto the rigidly mounted scavenging mandrel of the habitat carriage. 
         [0024]    The habitat and trapping flap serves to enlarge the habitat surface, and hence improve the harvest yield. In order to increase the latter even further, the habitat and trapping basket of the habitat carriage can advantageously be fitted with attractive add-ons for colonization by the hardground animals, for example closed or halved tube pieces, and/or additional pivoting small flap baskets at the lower end of the habitat and trapping basket. The flap baskets swivel into the horizontal position when retrieving the habitat carriage, making it possible to also harvest animals that fall out of the habitat and trapping basket, and animals from the space between the habitat and trapping basket and edifice. In addition, the positioning stability of the habitat and trapping basket and the habitat and trapping flap can be improved by providing penetrating mandrels at the lower end of the habitat and trapping basket and/or at the upper end of the habitat and trapping flap. When the habitat carriage and habitat and trapping flap are placed on the seafloor, these mandrels provide stabilization by digging into the soft seafloor. When retrieving the habitat carriage, they are simply removed from the soft seafloor again. 
         [0025]    In addition, the habitat and trapping basket of the habitat carriage can be straight, curved or angled in its horizontal cross section. This allows it to be optimally adjusted to the surface shape of the offshore edifice. A curved shape is advantageous in particular in light of the generally round pylons of air power plants. Finally, a brush arrangement that touches the offshore edifice can advantageously be provided over the width of the habitat carriage. As a result, animals colonizing the gap are brushed off when hauling up the habitat carriage. If desired, these animals can be harvested as well in the lower trapping baskets on the habitat carriage. Otherwise, they drop to the floor, and are there used by the colonizing animals as nutrition. The same applies to colonized fauna, so that the surface of the edifice is thoroughly cleaned in the area of the device according to the invention. Other design details relating to the device according to embodiments of the present invention can be gleaned from the exemplary embodiments described below. 
         [0026]      FIG. 1  shows an offshore edifice  01  in the form of a pylon  02  of a wind power plant with a vertically arranged rail device  03 . The rail device  03  is here designed as a simple T-shaped guide rail  04 , and extends over the height  05  of the underwater region  06  until above the waterline  07 . The rail device  03  has a vertically movable scavenging carriage  08 , which consists of a basic unit  09  and a running unit  10 . In the exemplary embodiment shown, the running body  10  of the scavenging carriage  08  is placed on the guide rail  04  in the area of recesses  49 . To enable threading at various heights, several recesses  46  can be provided along the guide rail  04  above the waterline  07 . The scavenging carriage  08  can also be placed on the end of the guide rail  04 , for example if the end can be reached from a boat. The running unit  10  rolls onto the guide rail  04  via running rollers  46 . In addition, the depicted scavenging carriage  08  has a guide roller  11  that abuts the offshore edifice  01 , and weights  12  that exert a force via a rotatable lever arm  13  horizontally on the offshore edifice  01  on the scavenging carriage  08 , thereby reliably preventing the scavenging carriage  08  from lifting up due to upward drift, currents and wave dynamic. The lever arm  13  is here pivoted to a transverse axis  48  in the spacer  25 . Additional weights  14  are also provided to increase the drifting rate of the scavenging carriage  08  (similar to habitat carriages  22 ). 
         [0027]    The upper end of the scavenging carriage  08  had an eyelet  15  for attaching a scavenging rope  16 , which is used to retrieve the scavenging carriage  08  via a lifting device  44 . The lower end of the scavenging carriage  08  has a reception flange  17  to secure various tools. In the embodiment shown, the reception flange  17  accommodates a scavenging bracket  18  (detailed sectional view). The scavenging bracket  18  has an introduction area  19  and, in the exemplary embodiment shown, flap segments  20  with an opening lever  46 , which serve to securely, but detachably, hold a scavenging mandrel  21 . This scavenging mandrel  21  is denoted with dashed lines on  FIG. 1 , and belongs to a habitat carriage  22  explained in greater detail on  FIG. 3 . As evident from  FIG. 1 , the shoulder  23  of the scavenging mandrel  21  sits on the flap segments  20  after having been retrieved by submerging the scavenging carriage  08  or scavenging bracket  18  through the introduction area  19  inside the scavenging bracket  18 , and lifted up the flap segments  20 . The scavenging mandrel  21  is detached from the scavenging bracket  18  by simply jimmying the unloaded flap segments  20  with an opening lever  47 . 
         [0028]      FIG. 2  shows a cross section through the pylon  02 , the rail device  03 , the basic unit  09  and the running unit  10 . Both the scavenging carriage  08  and the habitat carriage  22  essentially exhibit a basic unit  09  and a running unit  10 , which can advantageously be identical in design, but do not have to be. As evident from the cross section, the rail device  03  is formed by the T-shaped guide rail  04 . For example, this case can involve a simple steel rail securely welded to the pylon  02 . The basic unit  09  has a running unit  10  with a T-shaped guide groove  24 , which overlaps the T-shaped guide rail  04 . This yields a reliable axial and good radial guidance. To improve the latter even more, the basic unit  09  also has spacers  25  to laterally stabilize the basic unit  09 . The latter are trapezoidally molded out of a tube in the exemplary embodiment shown. The arrangement described above with lever  13  and weight  12  to press the scavenging carriage  08  or habitat carriage  22  against the edifice  01 ,  02  is not shown in any greater detail on  FIG. 2 . Two such arrangements are essentially situated to the right and left on scavenging carriages  08  or habitat carriages  22 . The rotatable levers  13  are mounted on a longitudinal axis between the spacers  25  situated between the transverse axis  48 . 
         [0029]    In addition,  FIG. 2  shows a habitat and trapping basket  26  as a netting array  45  with dashed lines to highlight its different possible shapes. In the case of the round pylon  02 , a correspondingly curved variant is advantageous (variant a). As an alternative, it can also be polygonal (variant b). Given flat surfaces of the offshore edifices  01 , the habitat and trapping basket  26  can also be given a correspondingly planar design (variant c). Also depicted is the width  27  of the basic unit  09  of the habitat and trapping basket  26 , which influences its stability and effectiveness relative to growing and harvesting the hardground animals. 
         [0030]      FIG. 3  shows a side view of the submerged habitat carriage  22 , which in conjunction with the rail device  03  and scavenging carriage  08  makes up the main components of the device  28  according to the invention. The basic unit  09  and running unit  10  of the habitat carriage  22  are shown, wherein the running unit  10  engages the T-shaped guide rail  04  of the vertical rail device  03 . The basic unit  09  of the habitat carriage  22  carries the habitat and trapping basket  26 , which has a habitat and trapping flap  29  that is opened in the state depicted. The habitat and trapping basket  26  is submerged to maximum depth via the rail device  03  while still preserving the coupling, and secured to the seafloor  31  by a penetrating mandrel  30  that digs into the ground. The habitat and trapping flap  29  is opened all the way, and also anchored to the seafloor  31  by means of another penetrating mandrel  32 . In this way, the habitat and trapping basket  26  and habitat and trapping flap  29  are effectively safeguarded against slippage caused by exposure to sea currents. The habitat and trapping basket  26  and habitat and trapping flap  29  have nettings  33  and various add-ons  34  for effectively harvesting and colonizing marine hardground animals  35 . The add-ons  34  are situated on either side of the basic unit  09  and the habitat and trapping flap  29 . They can exhibit known shapes, and take the form of tubes or half-tubes  36  in the case of add-ons  34 . Also provided are small flap baskets  37 , which are used for additional harvesting when retrieving the habitat carriage  22 . In the selected exemplary embodiment, these flap baskets  37  are connected with the habitat and trapping flap  29 , and pivoted simultaneous with their closure. One flap basket  37  also has a brush arrangement  38  used to clean and strip animals and plants on the pylon  02  during retrieval (see also  FIG. 5 ). 
         [0031]    For retrieval purposes, the upper end of the basic unit  09  of the habitat carriage  22  has the fixed scavenging mandrel  21 . The latter has a reception pin  39 , which detachably accommodates another scavenging mandrel  40 . This additional scavenging mandrel  40  is connected with two flap ropes  41  (see  FIG. 5 ), which each are guided through an eyelet  42  at the upper end of the habitat and trapping basket  26 , and securely fastened with the upper end of the habitat and trapping flap  29 . While being submerged, the scavenging bracket  18  of the scavenging carriage  08  overlaps the additional scavenging mandrel  40 , pulling it down from the reception pin  39  during retrieval of the scavenging carriage  08 . Pulling up the flap rope  41  initially closes the habitat and trapping flap  29  (arrow with flap rope  41  shown with dashed lines and taut), after which the habitat carriage  22  is pulled up. If the additional scavenging mandrel  40  slips out of the scavenging bracket  18  or be otherwise removed, or if the flap ropes  41  tear, the habitat carriage  22  can now still be safely scavenged via the fixed scavenging mandrel  21  by again hooking in the scavenging bracket  18 . The habitat and trapping flap  29  again opens and releases part of the catch, but does not further impede the scavenging process.  FIG. 3  shows another spacer  43  for stabilizing the habitat carriage  22  during submergence and retrieval. 
         [0032]      FIG. 4  shows the submerged, opened habitat carriage  22  according to  FIG. 3  in a perspective view; the corresponding reference numbers and explanations can be gleaned from  FIG. 3 . As clearly evident from  FIG. 4 , the two flap ropes  41  are on the upper end of the habitat and trapping flap  29 , and the half-tubes  36  on the netting  33 . 
         [0033]    Finally,  FIG. 5  shows the closed habitat carriage  22  during retrieval with the scavenging carriage  08 ; the corresponding reference numbers and explanations can again be gleaned from  FIG. 3 . Clearly evident in this depiction are the closed habitat and trapping basket  26  with the pulled up habitat and trapping flap  29 , and the flap basket  37  that is folded into a horizontal positon as a result, and the brush arrangement  39  that brushes off the pylon  02 . 
         [0034]    While the invention has been particularly shown and described with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention. 
       REFERENCE LIST 
       [0000]    
       
         
           
               01  Offshore edifice 
               02  Pylon 
               03  Rail device 
               04  T-shaped guide rail 
               05  Height of underwater region 
               06  Underwater region 
               07  Waterline 
               08  Scavenging carriage 
               09  Basic unit 
               10  Running unit 
               11  Guide roller 
               12  Weight 
               13  Lever arm 
               14  Additional weight 
               15  Eyelet 
               16  Scavenging rope 
               17  Reception flange 
               18  Scavenging bracket 
               19  Introduction area 
               20  Flap segment 
               21  Scavenging mandrel 
               22  Habitat carriage 
               23  Shoulder 
               24  T-shaped guide groove 
               25  Spacer 
               26  Habitat and trapping basket 
               27  Width of basic unit 
               28  Device for colonizing and harvesting marine hardground animal 
               29  Habitat and trapping flap 
               30  Penetrating mandrel 
               31  Seafloor 
               32  Additional penetrating mandrel 
               33  Netting 
               34  Add-on 
               35  Marine hardground animal 
               36  Half-tubes 
               37  Flap basket 
               38  Brush arrangement 
               39  Reception pin 
               40  Additional scavenging mandrel 
               41  Flap rope 
               42  Eyelet 
               43  Additional spacer 
               44  Lifting device 
               45  Netting array 
               46  Running roller 
               47  Opening lever 
               48  Transverse axis 
               49  Recess in T-shaped guide rail