EP0104221A1 - A method for cultivating water-living animals - Google Patents

Abstract

In a combined process of breeding and cultivating aquatic animals (6) with aquatic plants carrying out photosynthesis, the plants, preferably macrophytes, are cultivated on land, and not in a volume of water. They are kept moist by the continuous application of a film of water, preferably by spraying or draining (4). The combined cultivation and breeding process is applied using animal breeding water, rich in N and P, to moisten the plants and at the same time as a source of plant nutrients. The plants purify the water by consuming its N and P content, and the purified water can be reused in the system (in 9, 10) or discharged without risk to the environment. Animals can be raised in a separate volume of water (20) or on land with the plants.

Description

• A method for cultivating water-living animals.

The present invention relates to a method and a device for cultivating, or farming, fresh water or marine plants in mixed cultures with fresh water or marine animals.

Fresh water and marine organisms represent important sources of a 5 variety of valuable products, such as food and chemicals. The value of animals living in water, such as fish, arthropods and shell fish are well known. Macro and micro algae are presently used for producing food, proteins, agar, alginates, carragenins, antibiotics, vitamins, amino acids, etc. The current demand for these useful products greatly exceeds their availability, at least on an 10 economical basis.

Previous attempts for large scale commercial farming of algae include use of platforms in the sea, containers with open upper surfaces, flow through transparent plastic tubes, open ponds in which the culture is stirred or agitated. These cultures, however, have certain disadvantages such as lack of protection 15 against dirt and foreign organisms, lack of HCO_~ or CO-, and lack of light. In open ponds, for example, the light is insufficient for growth of microalgae in large scale more than about 2 cms below the water surface. Thus, these attempts have proved to be inefficient and uneconomical.

US-A- ,209,9 3 (Moeller et al) discloses an improved technique for 20 cultivating freshwater and marine macrophytes. The basic idea of this technique is not to cultivate the macrophytes in their native aqueous habitate, but on land, in a controlled, substantially closed atmosphere, in which the plants may be continually wetted by nutrient-containing water, either fresh or marine. Although this technique was a considerable improvement, e.g. as to optimizing 25 conditions as to light, temperature and nutrition utilization, it was only concerned with macrophytes, and the patent does not disclose or suggest .any combination with cultivation of water-living animals. -

Cultivation of fish, mussles, and the like has nowadays been developed both as fishfarming in the sea in nets and as fishfarming in ponds on land. In both 30 cases the water is polluted with great amounts of N and P due to the fish faeces and the food pellets given to the fish. Consequently, water pollution is a great problem, putting severe limitations on commercial farming of fish and other attractive water-living animals.

. The present invention is based on the discovery that combined cultivation 35 (or mixed culture) of water-living plants together with water-living animals results in considerable improvements of the animal cultivation while at the same maintaining an effective plant production. It is an object of the present Invention to provide a method suitable for large scale production of mixed cultures of plants and animals, which are naturally found in sea or fresh water.

A further object of this invention is to provide a method of the above character providing optimal growth and maximal yield of both plants and animals.

Another object of this invention is to provide a method which is econo¬ mical and efficient with respect to energy costs for maintaining and harvesting said plants and animals. Another object of this invention is to provide a method in which the content of nitrogen and phosphorus in the water from the animal culture is decreased due to the capability of the photosynthesizing plants to efficiently remove the nitrogen and phosphorus from the water, thus purifying the same.

Another object of this invention Is to provide a method in which the animals can be kept in full control during the whole growth period and be properly fed during this growth period.

Another object of this invention is to provide a method in which the animals are protected and kept moistured by the plants.

A still further object of the invention is to provide a method of the indicated type which only requires a minimum of water.

The above and further objects and advantages of the invention will be evident from the following description of pre erred embodiments.

As used herein the term "water-living plants" means macrophytes, micro algae and cyano bacteria, the term "macrophytes" including macro algae and water phanerogams. Similarly the term "water-living animals" includes fish, Mollusca, Crustaceae, Reptilia, Amphibia, both those living in fresh water and in salt water. The terms "combined cultivation", "mixed culture¹-¹ and the like mean that the plants^and the animals are -cultivated-in conjuction in- a manπer such that the plant culture receives water from the animal culture in a controlled manner. These terms include embodiments in which the animals are cultivated physically separated from the plants, water from the animal cultivation being supplied to the plant cultivation, e.g. by suitable conduit and pumping means, as well as embodiments in which the plants and the animals are physically mixed together, thus being wetted by "the same" water. In accordance with the invention, water from the animal culture, which is rich in N and P and thus is a potential environmental hazard, is thus used also for the plant culture. The N and P of this water is consumed by the plants, thus leaving purified water having a low content of N and P. This water is preferably recirculated, but it can also be discarded without harming the environment, because of the depletion of N and P. The plants may produce and exude antibiotics or other substances, which assist in keeping the animals free from infections and promote their growth. When kept physically mixed the plants also are effective in keeping the animals moistured and protected. In a preferred embodiment of the invention at least the plants are cultivated by essentially the same "on land" technique as disclosed in the above mentioned US-A-Ψ,209,9Ψ3 (which is incorporated by reference herein), i.e. the plants are not grown in a water mass, but on land, only being wetted - such as by spraying - with sufficient amounts of water for efficient cultivation. It is especially preferred to only form a film of water on the plants.

It is, however, to be understood that the invention in its broadest aspect is intended to include any manner of cultivating water-living plants or water- living animals, as long as the cultivation thereof is combined or coordinated as indicated herein, i.e. with controlled water supply so that the N and P rich water from the animal culture is used as a nutrition source for the plant culture. Thus, animals like fish may be cultivated in a water mass, such as a pond, with controlled supply and discharge of water, but certain fish species may also ^"be suited for "on land" farming, in which case the plants can play an important role in keeping the fish moistered. Flatfish such as turbot may be suitable for such farming. The plants can also be farmed by any other suitable technique.

When cultivating water-living animals in a mixture culture with water- living plants in accordance with the invention, several important advantages are obtained. For example, the growth of the animals is considerably improved, as is also the quality thereof. The control, feeding and harvesting of the animals is facilitated, especially when also the animals are cultivated "on land". The water ^"from the animal cultivation serves as a nutrition source (nitrogen arid phosphorus) for the plants, which clean the water so that it can be reused, if desired, for the animal cultivation or be disposed of without damaging the environment.^" The method also provides for improved food utilization/food control for the animals. Antibiotic substances and other substances produced and exuded by the algae can also help to keep the animals free of infections and improve their growth. The plants and the animals need not be harvested at the same time, but they can be harvested individually at any desired time.

The invention will be explained in further detail below with reference to the enclosed drawings showing some examples of illustrative but non-limiting embodiments of the invention. In the drawings

Figure 1 is a schematic perspective view, with parts broken away, of a greenhouse-like housing illustrating a first embodiment of the method according to the invention, with joint cultivation of mussles and macrophytes, Figure 1A is a schematic perspective view of part of a cultivation bed used in the housing of Figure 1,

Figure 2A is diagrammatic view illustrating a second embodiment of the cultivation method according to the invention, wherein macro algae are cultivated in a greenhouse-like housing, the co-cultivated animals (such as fish) being cultivated in separate ponds or the like,

Figure 2B is a diagrammatic view illustrating a variant of the embodiment of Figure 2A, wherein the the plants are cultivated on top of the pond to facilitate recirculatϊon of water from the plants to the animals, and Figure 3 is a schematic perspective view illustrating a variant of the embodiment of Figure 1 using cage like beds to keep the animals enclosed.

In Figure 1 there is shown a greenhouse-like housing 1 which forms an enclosed cultivation space, wherein a controlled atmosphere can be maintained, i.e. an atmosphere which can be controlled as to humidity, temperature and, where necessary, light. Inside the housing 1 there is provided a water spray or a sprinkler system 2, which in the shown embodiment comprises a feed pump 3 supplying feed water to a plurality of spray nozzles • . The spray nozzles are shown located above cultivation beds 5, on which the plants and the animals are cultivated. In the shown embodiment the beds 5 consist of rectangular frames of a water permeable net serving as a cultivation substrate for the plants and animals. In the illustrated case the animals 6 are oysters, blue mussles or the like, which are mixed on the beds with macro algae such as green, red or brown algae. A plurality of individual beds can be placed on top of each other (two are shown in Fig. 1) and/or adjacent to each other in the same greenhouse structure. The spray nozzles are arranged so as to wet the algae and animals, preferably keeping a water .charged atmosphere, inside the housing. Excess of . water falls down onto the floor 7 of the greenhosue and escapes to a sink 8 therein. The system shown in Figure 1 is arranged for reuse of the excess -water, and to this end the floor of the greenhouse is designed as a water reservoir 11. A circulation pump 9 and a conduit 10 recirculate the excess water to the spray system 2, .

The plants, such as macro algae, and the animals, such as mussels, are placed on the bed 5 and kept moistered - e.g. by a thin water film - by means of water supplied by the pump 3. The nozzles -t- divide the water into droplets, a fine mist, etc. The animals produce exudates containing N and P, which are efficiently consumed by the plants. As a result, the water passing into the drain 8 is comparatively pure and low in N and P. This water may be discarded, but it is preferably recirculated to the spray system 2, • by means of the pump 9 and the conduit 10. Such a system consumes very small amounts of water, partly becat, of the fact that the plants/animals are only covered by a film of water instead of being in a large water mass, partly by the re-use of water through recirculation system 9, 10.

Keeping the animals moistured on land on plant (algal) beds provides for better control of sick animals, which can be removed, more efficient food distribution (food utilization), growth control, etc. Also the harvesting of the animals is facilitated. Young animals can be separated from adults, females from males, etc. The animals could be sprayed with greater amounts of water occasionally to be freed from dirt or epiphytes. Antibiotics, hormones, fungicides, herbicides, vitamins could also be added in controlled and efficient manner by spraying. The algal beds will keep the moisture and remove N and P from the water and also shelter and protect the animals if the beds are kept thick enough. The algae may also exude antibiotic substances, which will help to keep the animals free of infections. The algae can also produce vitamins, amino acids, carbohydrates which are also exuded into the water and could be used by the animals.

As many animals -need -to grow for- several years before harvesting, the algae, which usually grow very fast with the spray-cultivation technique, can be conveniently be harvested at any time. The main results of the cultivation method of the invention are thus

1) . ^' high yields of high quality animals,

2) high yields of plants, and - - .. . . - .

3) clean (waste) water.

The embodiment illustrated in Fig.l is preferred for oysters, mussels and similar. animals, in which case preferred plants are macro algae, such as green, red and brown algae. -- • -— — - -- ■ - .-. .— -

The invention is not intended to be restricted to the particular spray or sprinkler system shown -in Fig. 1, but any water distribution system ^"~ capable xή" providing the necessary wetting of the plants/animals can be used. Not either is the design of the beds 5 critical, but any alternative support capable of serving as a substrate or support surface for the plants and/or animals in question can be used. The beds are usually chosen with regard to the particular animals/plants to be cultivated.

In the embodiment shown in Fig. 2A only the plants are cultivated on land in the greenhouse-like housing similar to the one shown in Fig. 1, whereas the animals, such as fish, are farmed in an artificial pond 20. A pump 21 pumps water from the pond 20 to the sprinkler system 2 in the housing 1. Water discharged from the housing 1 may be discarded, but is preferably recirculated to the pond 20 via a conduit 22, driven by gravity or by a suitable pump (not showr As in the embodiment of- Fig. 1 the animals will cause the water in the pond 20 to become rich in N and P, which in turn are consumed by the plants in the housing 1. This embodiment is preferred for cultivation of fish, especially salmon type fish and the like, preferably in combination with bluegreen and/or green algae in the housing 1.

Fig. 2B shows a variant of the embodiment of Fig. 2A. In this case the housing 1 is placed on top of the pond 20, water from the housing 1 being recirculated to the pond directly by gravity.

Fig. 3 illustrates a variant of the embodiment of Fig. 1, adapted for animals which have to be "caged" in order to stay on the beds, e.g. lobsters, crabs, crayfish, and the like, but also certain fishes such as flatfish, e.g. turbot. In this embodiment the cultivation beds are provided with nets 30 on all sides to form cages for the animals. Fig. 3 also shows an alternative arrangement of the spray nozzles 31, which in this case spray water from the sides of the cages, in the case shown with one row of spray heads or spray nozzles for each vertical cage level.

It should be obvious from the above disclosure that the method .according to the invention can be modified and complemented with various secondary features without departing from the scope of the appended claims. For example, it should be obvious that the method offers a plurality of alternatives in details as regards the control of ligh, temperature, humidity, wetting of plants and animals, the method of supplying nutrition to the plants and animals, etc., and the person skilled in the art would be able to optimize these and related parameters and conditions on the basis of this disclosure. For example, it would be possible to provide only a partial enclosure for the plants/animals instead of the full greenhouse-like enclosure -shown in the drawings, e.g. by leaving -out the roof or one or more walls thereof. Although some parameters of the environment of the plants/animals could not controlled - to -the same extent as in a full enclosure, it would in certain instances be sufficient to cultivate at least the plants on land in an only partly enclosed, wind-shielded area, the plants (animals) being cultivated on suitable beds and kept moistured by spraying, as explained above.

fϋRE

OMPI

Claims

CLAIMS 1. A method of cultivating water-living animals, characterized by the following combination of steps:

(a) the water-living animals are co-cultivated with photosynthesizing water- living plants,

(b) the water-living plants are cultivated on land in an at least partially enclosed area and are kept moistured by substantially continuous application of a water film thereon,

(c) the co-cultivation is carried out in a manner such that water from the animal cultivation, which is rich in N and P, is supplied to the plants to form said water film thereon and to serve as a nutrition source for the plants, which purify the water by consuming N and P contained therein.

2. The etod of claim 1, wherein the plant cultivation is carried out in a greenhouse-like housing, in which a controlled atmosphere as to humidity and temperature can be maintained.

3. The method of claim 1, wherein the plant cultivation is carried out in a wind-shielded partial enclosure.

. The method of claim 1, 2 or 3, wherein the plants are kept moistured by substantially continuously spraying or dripping water thereon.

5. The method of any one of claims 1 to , wherein the animal cultivation is carried out in an enclosed water mass, separated from the plant cultivation, and wherein water taken from the water mass and being enriched in N and P is supplied to the plant cultivation for keeping the plants moistured,- the ^*water,- - after having been depleted on N and P in the plant cultivation, pre erably being fed back to said water mass for re-use therein. ^"

6. The method of any one of claims 1 to , wherein the water-living animals are cultivated together with the water-living plants on land in said at least partially enclosed area, the animals being kept moistured by said water film and preferably also by contact with the plants.

7. The method of claim 6, wherein excess water from said mixed culture of plants and animals is collected and recirculated for repeatedly keeping the plants and animals moistured.

8. The method of any one of the preceding claims, characterized in that the water-living animals are selected from the grouD consisting of fish, Mollusca, Crustaceae, Reptilϊa, and Amphibia, and in that the water-living plants are selected from the group consisting of macrophytes, including macro algae and water phanerogams, micro algae, and cyano bacteria.

9. The method of claim 8, wherein the animals and plants are selected from the group consisting of the following combinations: a) Salmon type fish - blue-green algae and green algae b) Flatfish - macro algae c) Crayfish - water phanerogams, green algae and crown algae d) Lobster - green, red and/or brown macro algae e) Oysters or blue mussels - green, red and/or brown macro algae.

10. The method of any one of claims 1 to 9, wherein at least the water-living plants are cultivated on water permeable cultivation beds, at least certain of which are placed on top of each other, so that excess water from an upper cultivation bed can pass through the same and fall down to a lower cultivation bed.