A feed additive suitable for the planktonic larvae of intertidal shellfish, and a preparation method and application thereof

Abstract

The application provides a feed additive suitable for beach shell plankton larvae and a preparation method and application thereof, and the feed additive is prepared from core material and wall material in a mass ratio of (1-2):(2-1); raw materials of the core material include 2-3 parts of leucine, 2-3 parts of isoleucine, 2-3 parts of valine, 2-3 parts of taurine, 0.5-1 part of high-temperature sterilized sea mud and 85-95 parts of water; and raw materials of the wall material include 3-7 parts of beta-cyclodextrin, 3-7 parts of methyl cellulose and 85-95 parts of water. The preparation method comprises the following steps: S1, preparing a core material solution and a wall material solution; S2, mixing and stirring to obtain a mixed solution; and S3, spray drying the mixed solution to prepare microcapsules and storing, and the preparation is completed. The feed additive prepared by the application can effectively improve the survival state of the plankton larvae, solves the problem that direct feeding of amino acids has an influence on water quality, and has the advantages of simple production process, stable procedure, easy control, high success rate, and suitability for enterprises and breeders.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of aquaculture, in particular, to a feed additive for planktonic larvae of intertidal shellfish, a preparation method and application thereof. BACKGROUND

[0002] The yield of bivalve cultivation accounts for more than 70% of the yield of marine aquaculture in China, among which, intertidal shellfish such as clams, ark shells and littlenecks accounts for about 55% of the cultivated shellfish. At present, more than 90% of the seedlings of intertidal shellfish are cultivated in factory cement pools. Under the condition of cement pool cultivation, the development of shellfish needs to go through three main stages of D-type larvae, shell top larvae and juvenile shellfish, among which, the D-type larvae and shell top larvae are called planktonic larvae. The nutritional history of planktonic larvae will affect the state of the larvae, and the state of the planktonic larvae will directly affect the change of the entire population, such as the metamorphosis and survival of the planktonic larvae. Therefore, there is an urgent need for a special feed additive to improve the survival state of planktonic larvae.

[0003] At present, the feed additive technology for intertidal shellfish is still blank, not to mention the feed additive specially suitable for planktonic larvae of intertidal shellfish. The current feed additive technology and commercially available products for aquatic animals such as fish, shrimp and crab cannot be applied to intertidal shellfish. Firstly, the planktonic larvae are small in size, and have a requirement for the size of microcapsules, which cannot be greater than 10 μm; secondly, intertidal shellfish are filter feeders, which are completely different from the feeding mode of fish, shrimp and crab. In addition, among the existing patent technologies of "shellfish feed", there is also no special stage suitable for planktonic larvae of intertidal shellfish. Therefore, it is particularly important to develop a feed additive that can be applied to planktonic larvae and improve their state.

[0004] Proteins are important components of various organisms, and can account for 60-65% of the dry weight of intertidal shellfish. Because of the low amylase activity in the digestive tract of aquatic animals, the utilization of carbohydrates is low, and thus proteins become the main functional material. Free amino acids are mainly used as substrates for protein synthesis and energy sources for aerobic metabolism. During the early development of embryos and larvae of marine organisms, free amino acids are used to maintain the osmotic pressure of the body fluid. Studies have found that most aquatic animals require essential amino acids to maintain their normal growth and development, and the lack or deficiency of any one essential amino acid can lead to a series of problems such as growth decline. The content of essential amino acids is the highest during the entire development of bivalves, especially during the planktonic larval stage. Branch chain amino acids (BCAA) account for 40% of essential amino acids, and sufficient addition and reasonable proportion are very important for the normal development of aquatic animals. Branch chain amino acids include leucine, isoleucine and valine. Branch chain amino acids are essential amino acids for aquatic animals to maintain growth, and cannot be synthesized in the animal body, and must be obtained from the diet. Taurine, as a common additive in aquatic animal feed, is also an important functional amino acid, and the content of taurine remains at a high level during the development of bivalve larvae. The lack of taurine in feed can cause some aquatic animals to grow slowly and have a series of adverse symptoms. The addition of amino acids can significantly improve the immune function of aquatic animals, and branch chain amino acids and taurine perform more obviously. After searching, no related patents and literature reports on the application of related amino acids in the planktonic larvae of intertidal shellfish have been found.

[0005] Intertidal shellfish grow in mud-rich intertidal zones. Studies have found that the intake of sea mud is beneficial to the growth and development of mollusks (Liu Y, Dong S, Tian X, et al. Effects of dietary sea mud and yellow soil on growth and energy budget of the sea cucumber Apostichopus japonicus (Selenka) [J]. Aquaculture, 2009, 286 (3-4): 266-270.). Sea mud contains numerous mineral elements and unknown nutritional active substances required for shell growth, which can provide nutrition for intertidal shellfish. After searching, no related patents and literature reports on the application of sea mud in the planktonic larvae of intertidal shellfish have been found. SUMMARY

[0006] One of the technical problems solved by the present application is to provide a feed additive suitable for planktonic larvae of intertidal shellfish, so as to solve the problem that conventional feed additives cannot improve the survival state of planktonic larvae and are not suitable for planktonic larvae.

[0007] To solve the above problems, the present application provides a kind of feed additive suitable for tidal flat mollusk planktonic larvae, the feed additive is prepared by core material and wall material, and the mass ratio of the core material and wall material is (1-2) :(2-1);

[0008] The raw materials of the core material include: leucine 2-3 parts, isoleucine 2-3 parts, valine 2-3 parts, taurine 2-3 parts, high-temperature sterilization sea mud 0.5-1 part, water 85-95 parts;

[0009] The raw materials of the wall material include: β-cyclodextrin 3-7 parts, methyl cellulose 3-7 parts, water 85-95 parts.

[0010] The present application is suitable for tidal flat mollusk planktonic larvae feed additive and the prior art is compared, at least has the following advantages:

[0011] The conventional method has a great influence on water quality by directly feeding amino acids, and the microorganisms in the water can directly absorb the amino acids, so that the number of microorganisms in the water increases, causing the water quality to deteriorate, and further causing the survival environment of the tidal flat mollusk planktonic larvae to deteriorate, which cannot improve its state, and ultimately accelerates its death. The present application avoids the direct dissolution of amino acids in water by first preparing an aqueous solution of amino acids and then spray drying to form microcapsule particles, so that the amino acids can be directly ingested by the tidal flat mollusk, and water quality deterioration is also avoided.

[0012] As a preferred scheme, the mass ratio of the core material and wall material is 1:1.

[0013] As a preferred scheme, the raw materials of the core material include: leucine 2.3 parts, isoleucine 2.3 parts, valine 2.3 parts, taurine 2.3 parts, high-temperature sterilization sea mud 0.8 part, water 90 parts.

[0014] As a preferred scheme, the raw materials of the wall material include: β-cyclodextrin 5 parts, methyl cellulose 5 parts, water 90 parts.

[0015] One of the technical problems to be solved by the present application is to provide a preparation method of a feed additive suitable for tidal flat mollusk planktonic larvae, to solve the problems of conventional preparation methods, such as environmental unfriendliness, complex production process and low efficiency.

[0016] To solve the above problems, the present application also provides a preparation method of the feed additive, comprising the following steps:

[0017] S1: leucine, isoleucine, valine and taurine are added to water, mixed uniformly, and then high-temperature sterilization sea mud is added and mixed uniformly to obtain a core material solution;

[0018] The beta-cyclodextrin and methyl cellulose are added into water, and a wall material solution is obtained after uniform mixing;

[0019] S2: the core material solution and the wall material solution are mixed and stirred to obtain a mixed solution;

[0020] S3: the mixed solution is spray-dried to obtain microcapsules, and the microcapsules are stored.

[0021] Compared with the conventional technology, the preparation method has at least the following advantages: the production method has low raw material cost, simple operation, can realize large-scale production, the whole production process is mild, no toxic substances are taken in, and the survival state of the planktonic larvae can be effectively improved. At the same time, the production process is simple, the program is stable, easy to control, the success rate is high, and it is suitable for enterprises and breeders to adopt.

[0022] As a preferred scheme, in the step S1, the preparation method of the high-temperature sterilized sea mud comprises: taking sea mud in the survival environment of the intertidal zone, adding 100 DEG C boiling water and stirring, and filtering through a 1000-mesh screen, collecting the precipitate, and then exposing the collected precipitate to sunlight until it becomes a block, to obtain the high-temperature sterilized sea mud.

[0023] As a preferred scheme, in the step S2, the stirring time is greater than 20 minutes.

[0024] As a preferred scheme, in the step S3, the spray-drying conditions are: the inlet air temperature is 140-150 DEG C, and the outlet air temperature is 76-82 DEG C.

[0025] As a preferred scheme, in the step S3, the storage conditions are: the microcapsules are stored in an environment of-20 DEG C.

[0026] Another technical problem to be solved by the present application is to provide an application of a feed additive suitable for planktonic larvae of intertidal zone shellfish. The application comprises applying the feed additive to the feeding of the planktonic larvae of the intertidal zone shellfish.

[0027] As a preferred scheme, the feed additive is added in the following way: the feed additive is dissolved in water, filtered through an 800-mesh screen, and fed to the planktonic larvae of the intertidal zone shellfish, and the light intensity during the culture of the planktonic larvae of the intertidal zone shellfish is less than 100 Lux. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 The scanning electron microscope image of the microcapsule;

[0029] Figure 2Fig. 1 is a diagram showing the metamorphosis rate of planktonic larvae of the examples and the comparative examples;

[0030] Figure 3 Fig. 2 is a diagram showing the survival rate of planktonic larvae of the examples and the comparative examples;

[0031] Figure 2 、 Figure 3 In the figure, control is the data of the comparative example 1, 0.75 mg, 1.5 mg and 3.0 mg represent the mass of the feed additive fed per 50 L of water body, respectively. DETAILED DESCRIPTION

[0032] The technical solutions of the present application will be described clearly and completely below. Obviously, the described examples are part of the examples of the present application, rather than all the examples. Based on the examples in the present application, all the other examples obtained by the ordinary skilled in the art without creative labor belong to the protection scope of the present application.

[0033] The present application provides a feed additive suitable for planktonic larvae of intertidal shellfish, which is prepared from core material and wall material, and the mass ratio of the core material to the wall material is (1-2):(2-1).

[0034] The raw materials of the core material include 2-3 parts of leucine, 2-3 parts of isoleucine, 2-3 parts of valine, 2-3 parts of taurine, 0.5-1 part of high-temperature sterilized sea mud, and 85-95 parts of water.

[0035] The raw materials of the wall material include 3-7 parts of β-cyclodextrin, 3-7 parts of methyl cellulose, and 85-95 parts of water.

[0036] Preferably, the mass ratio of the core material to the wall material is 1:1.

[0037] Preferably, the raw materials of the core material include 2.3 parts of leucine, 2.3 parts of isoleucine, 2.3 parts of valine, 2.3 parts of taurine, 0.8 part of high-temperature sterilized sea mud, and 90 parts of water.

[0038] Preferably, the raw materials of the wall material include 5 parts of β-cyclodextrin, 5 parts of methyl cellulose, and 90 parts of water.

[0039] The present application further provides a preparation method of the feed additive, which comprises the following steps:

[0040] S1: branched chain amino acids (leucine, isoleucine, valine) and taurine are added into water, and after being mixed uniformly, high-temperature sterilized sea mud is added and mixed uniformly to obtain a core material solution;

[0041] β-cyclodextrin and methyl cellulose are added into water, and after being mixed uniformly, a wall material solution is obtained;

[0042] S2: mixing the core material solution and the wall material solution, and stirring to obtain a mixed solution;

[0043] S3: spray drying the mixed solution to obtain microcapsules, and storing the microcapsules.

[0044] Preferably, in the step S1, the preparation method of the high-temperature sterilized sea mud comprises the following steps: taking sea mud in a beach shellfish living environment, adding 100 DEG C boiling water and stirring, filtering through a 1000-mesh screen, collecting the precipitate, and then exposing the collected precipitate to sunlight until it becomes a block, thereby obtaining the high-temperature sterilized sea mud.

[0045] Preferably, in the step S2, the stirring time is greater than 20 minutes.

[0046] Preferably, in the step S3, the spray drying conditions are as follows: the inlet air temperature is 140-150 DEG C, and the outlet air temperature is 76-82 DEG C.

[0047] Preferably, in the step S3, the storage conditions are as follows: the microcapsules are stored in an environment at-20 DEG C.

[0048] The application also provides an application of the feed additive suitable for beach shellfish planktonic larvae, which comprises applying the feed additive in the feeding of beach shellfish planktonic larvae.

[0049] Preferably, the feed additive is added in the following manner: the feed additive is dissolved in water, filtered through an 800-mesh screen, and then fed to the beach shellfish planktonic larvae, and the light intensity in the culture process of the beach shellfish planktonic larvae is less than 100 Lux.

[0050] The following provides specific embodiments to describe the above technical solutions of the application:

[0051] Embodiment 1

[0052] The embodiment provides a feed additive suitable for beach shellfish planktonic larvae, which is prepared from a core material and a wall material, and the mass ratio of the core material to the wall material is 1:1.

[0053] The raw materials of the core material comprise 2.3 parts of leucine, 2.3 parts of isoleucine, 2.3 parts of valine, 2.3 parts of taurine, 0.8 parts of high-temperature sterilized sea mud, and 90 parts of water.

[0054] The raw materials of the wall material comprise 5 parts of beta-cyclodextrin, 5 parts of methyl cellulose, and 90 parts of water.

[0055] The application further provides a preparation method of the feed additive, comprising the following steps:

[0056] S1: branched chain amino acids and taurine are added into water, mixed uniformly, and then high-temperature sterilized sea mud is added and mixed uniformly to obtain a core material solution; the preparation method of the high-temperature sterilized sea mud comprises the following steps: sea mud in a beach shellfish living environment is taken, boiled water at 100 DEG C is added, stirring is performed, and the mixture is filtered through a 1000-mesh screen to collect the precipitate; then the collected precipitate is exposed to sunlight until it becomes a block to obtain the high-temperature sterilized sea mud.

[0057] Beta-cyclodextrin and methyl cellulose are added into water, mixed uniformly to obtain a wall material solution;

[0058] S2: the core material solution and the wall material solution are mixed and stirred for more than 20 minutes to obtain a mixed solution;

[0059] S3: the mixed solution is spray-dried to prepare microcapsules, and the microcapsules are stored in an environment at-20 DEG C; the spray-drying conditions are as follows: the inlet air temperature is 145 DEG C, and the outlet air temperature is 79 DEG C.

[0060] Example 2:

[0061] The embodiment provides a feed additive suitable for beach shellfish planktonic larvae, the feed additive is prepared from a core material and a wall material, and the mass ratio of the core material to the wall material is 1:2.

[0062] The raw materials of the core material comprise 3 parts of leucine, 3 parts of isoleucine, 3 parts of valine, 3 parts of taurine, 1 part of high-temperature sterilized sea mud and 95 parts of water.

[0063] The raw materials of the wall material comprise 7 parts of beta-cyclodextrin, 7 parts of methyl cellulose and 95 parts of water.

[0064] The application further provides a preparation method of the feed additive, comprising the following steps:

[0065] S1: branched chain amino acids and taurine are added into water, mixed uniformly, and then high-temperature sterilized sea mud is added and mixed uniformly to obtain a core material solution; the preparation method of the high-temperature sterilized sea mud comprises the following steps: sea mud in a beach shellfish living environment is taken, boiled water at 100 DEG C is added, stirring is performed, and the mixture is filtered through a 1000-mesh screen to collect the precipitate; then the collected precipitate is exposed to sunlight until it becomes a block to obtain the high-temperature sterilized sea mud.

[0066] Beta-cyclodextrin and methyl cellulose are added into water, mixed uniformly to obtain a wall material solution;

[0067] S2: the core material solution and the wall material solution are mixed and stirred for more than 20 minutes to obtain a mixed solution;

[0068] S3: spray drying the mixed solution to prepare microcapsules and storing in an environment of -20 DEG C, the spray drying conditions are: inlet air temperature 150 DEG C, outlet air temperature 82 DEG C.

[0069] Example 3

[0070] The embodiment provides a feed additive suitable for planktonic larvae of intertidal zone shellfish, the feed additive is prepared from core material and wall material, and the mass ratio of the core material and the wall material is 2:1.

[0071] The raw material of the core material comprises: 2 parts of leucine, 2 parts of isoleucine, 2 parts of valine, 2 parts of taurine, 0.5 parts of high-temperature sterilized sea mud and 85 parts of water.

[0072] The raw material of the wall material comprises: 3 parts of beta-cyclodextrin, 3 parts of methyl cellulose and 85 parts of water.

[0073] The embodiment further provides a preparation method of the feed additive, comprising the following steps:

[0074] S1: adding branched chain amino acids and taurine into water, mixing uniformly, then adding high-temperature sterilized sea mud and mixing uniformly to obtain a core material solution; the preparation method of the high-temperature sterilized sea mud comprises the following steps: taking sea mud in an intertidal zone shellfish living environment, adding 100 DEG C boiling water and stirring, filtering through a 1000-mesh screen, collecting the precipitate, then exposing the collected precipitate to sunlight until the precipitate is in a lump shape to obtain the high-temperature sterilized sea mud.

[0075] adding beta-cyclodextrin and methyl cellulose into water, mixing uniformly to obtain a wall material solution;

[0076] S2: mixing the core material solution and the wall material solution and stirring to obtain a mixed solution;

[0077] S3: spray drying the mixed solution to prepare microcapsules and storing in an environment of -20 DEG C, the spray drying conditions are: inlet air temperature 140 DEG C, outlet air temperature 76 DEG C.

[0078] The above embodiment of the application is further expanded by combining specific actual data and specific raw material mass:

[0079] Example 4

[0080] The embodiment provides an amino acid microcapsule, which is composed of core material and wall material: 2.3g of leucine, 2.3g of isoleucine, 2.3g of valine, 2.3g of taurine, 0.8g of high-temperature sterilized sea mud and 90g of water as core material raw materials; 5g of beta-cyclodextrin, 5g of methyl cellulose and 90g of water as wall material raw materials.

[0081] The above-mentioned microcapsule preparation method: branched chain amino acids and taurine are added into water, mixed uniformly, and then high-temperature sterilized sea mud is added and mixed uniformly to obtain a core material solution. The core material solution is mixed with a β-cyclodextrin and a methyl cellulose aqueous solution at 1:1. Uniform stirring is performed for not less than 20 min, and spray drying is performed to prepare the microcapsule, with an inlet air temperature of 142°C and an outlet air temperature of 80°C. The finished product is collected and stored in a -20°C refrigerator.

[0082] The microcapsules prepared in this example are fed to the Philippines clam plankton larvae: 0.5 g of D-type larvae are cultured in 50 L of water, and water is changed once every two days. A sufficient amount of Chaetoceros liquid is fed at about 08:00 and 20:00 every day, and the algal cell density of the water is 100-120 / μL after each feeding. The microcapsules are fed at the same time as the Chaetoceros liquid, and three concentrations are set, 0.75 mg, 1.5 mg and 3 mg per 50 L of water, and three parallel groups are set for each concentration. The water temperature is 20-25°C, the salinity is 20‰, and the dissolved oxygen is maintained at 6 mg / L during the culture. After two weeks, the metamorphosis rate of the plankton larvae is shown in Figure 2 , the survival rate is shown in Figure 3 , and the Philippines clam plankton larvae have good activity, and the survival rate and metamorphosis rate are improved.

[0083] Comparative Example 1

[0084] The microcapsules prepared in this example 4 are fed to the Philippines clam plankton larvae: 0.5 g of D-type larvae are cultured in 50 L of water, and water is changed once every two days. A sufficient amount of Chaetoceros liquid is fed at about 08:00 and 20:00 every day, and the algal cell density of the water is 100-120 / μL after each feeding. Three parallel groups are set. The water temperature is 20-25°C, the salinity is 20‰, and the dissolved oxygen is maintained at 6 mg / L during the culture. After two weeks, the metamorphosis rate of the plankton larvae is shown in Figure 2 , the survival rate is shown in Figure 3 , and the Philippines clam plankton larvae have good activity and grow normally.

[0085] As shown in Figure 2 , Figure 3 , the Figure 2 is a schematic diagram of the metamorphosis rate and survival rate of the plankton larvae of example 4 and comparative example 1, including three parallel groups for each concentration, Figure 2The three parallel groups including error lines are also included in / 3. By comparing Example 4 with Comparative Example 1, it can be clearly found that by adding the microcapsules of the present application, the metamorphosis rate and survival rate of the planktonic larvae are effectively improved, and compared with the comparative example, whether adding 0.75 mg, 1.5 mg or 3 mg of the parallel group, the metamorphosis rate and survival rate are all better than those of the comparative example; secondly, the group adding 1.5 mg has a higher metamorphosis rate, in some parallel groups, the group adding 3 mg has a higher survival rate, the group adding 0.75 mg has a higher survival rate, in summary, the comprehensive performance of the case of the parallel group adding 1.5 mg in 50 L water is the best, the group adding 0.75 mg is the second, and in the culture process of the planktonic larvae, the light intensity must be ensured to be not greater than 100 Lux (according to the breeding experience of the breeding farm), when feeding the microcapsules, the dissolved microcapsule solution should be filtered with a 800 mesh sieve, which can improve the feeding rate of the planktonic larvae.

[0086] Although the present disclosure is disclosed as above, the protection scope of the present disclosure is not limited to this. Those skilled in the art can make various changes and modifications without departing from the spirit and scope of the present disclosure, and these changes and modifications will fall within the protection scope of the present application.

Claims

1. A method of preparing a feed additive suitable for use with planktonic larvae of intertidal shellfish, characterised in that: The method comprises the following steps: S1: adding leucine, isoleucine, valine and taurine into water, mixing uniformly, then adding high-temperature sterilized sea mud and mixing uniformly to obtain a core material solution; adding β-cyclodextrin and methyl cellulose into water and mixing uniformly to obtain a wall material solution; S2: mixing the core material solution and the wall material solution and stirring to obtain a mixed solution; S3: spray drying the mixed solution to prepare microcapsules, and storing the microcapsules, wherein the microcapsules are a feed additive suitable for planktonic larvae of intertidal zone mollusks; In the step S1, the preparation method of the high-temperature sterilized sea mud comprises the following steps: taking sea mud in an intertidal zone mollusk living environment, adding 100 DEG C boiling water and stirring, filtering through a 1000-mesh screen, collecting the precipitate, and then exposing the collected precipitate to sunlight until it becomes a block to obtain the high-temperature sterilized sea mud; The feed additive is prepared from a core material and a wall material, and the mass ratio of the core material to the wall material is (1-2):(2-1); the raw materials of the core material comprise 2-3 parts of leucine, 2-3 parts of isoleucine, 2-3 parts of valine, 2-3 parts of taurine, 0.5-1 part of high-temperature sterilized sea mud, and 85-95 parts of water; and the raw materials of the wall material comprise 3-7 parts of β-cyclodextrin, 3-7 parts of methyl cellulose, and 85-95 parts of water.

2. The method for preparing a feed additive suitable for use with pelagic larvae of intertidal shellfish according to claim 1, characterized in that: The mass ratio of the core material to the wall material is 1:

1.

3. The method for preparing a feed additive suitable for use with pelagic larvae of intertidal shellfish according to claim 1, characterized in that: The raw materials of the core material comprise 2.3 parts of leucine, 2.3 parts of isoleucine, 2.3 parts of valine, 2.3 parts of taurine, 0.8 part of high-temperature sterilized sea mud, and 90 parts of water.

4. The method for preparing a feed additive suitable for use with pelagic larvae of intertidal shellfish according to claim 1, characterized in that: The raw materials of the wall material comprise 5 parts of β-cyclodextrin, 5 parts of methyl cellulose, and 90 parts of water.

5. The method for preparing a feed additive suitable for use with planktonic larvae of intertidal shellfish according to claim 1, characterized in that: In the step S2, the stirring time is greater than 20 minutes.

6. The method for preparing a feed additive suitable for use with planktonic larvae of intertidal shellfish according to claim 1, characterized in that: In the step S3, the spray drying conditions are as follows: the inlet air temperature is 140-150 DEG C, and the outlet air temperature is 76-82 DEG C; and the storage conditions are as follows: storing the microcapsules in an environment at-20 DEG C.

7. Use of a feed additive suitable for use with planktonic larvae of intertidal shellfish, characterised in that: The application comprises applying the feed additive prepared by the preparation method in any one of claims 1-6 to the feeding of planktonic larvae of intertidal zone mollusks.

8. Use of a feed additive according to claim 7, characterized in that: The feed additive is added in the following manner: dissolving the feed additive in water, filtering through an 800-mesh screen, and then feeding the planktonic larvae of intertidal zone mollusks, and the light intensity in the culture process of the planktonic larvae of intertidal zone mollusks is less than 100 Lux.

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