An internet artist's place to write.Unfortunately this failed epically. Dead brine shrimp, everywhere we looked! So, this is my write-u. Hopefully it will serve as a warning to innocent would-be sea monkey enthusiasts *cruelly destroys optimism*
(EDIT: Apparently my lecturer secretly harbours a dislike of brine shrimp! He gave me an A for killing them all so spectacularly!)
Most useful links:
Raising Brine Shrimp
Brine shrimp in aquaculture
Brine shrimp (Artemia spp., phylum Arthropoda, class Crustacea) are a popular aquaculture live feed species. Live Artemia are one of the only available feeds for many finfish and crustacean larvae. They are the preferred feed due to the ease of preparation and the fact that most species will readily eat them, as well as for their nutritional value. They can be raised both in large scale commercial farms, and by hand at home, by tropical fish enthusiasts. There is investigation into mass production (Zmora et al., 2001) which appears to be highly promising, however many brine shrimp are sourced from a few suppliers.
They are an important food for many commercial species, such as Chinook salmon, lobster and shrimp, and there are numerous studies on the exact effects of brine shrimp diets for these species (e.g. Moore & Strom, 2002). The biochemical composition of the brine shrimp is an important aspect of larval nutrition and numerous enrichment procedures have been developed, or are being researched (e.g. fatty acid uptake to increase the lipid content of the diet (Ritar et al., 2004)).
Feeding live Artemia to fish can bring associated risks of disease and infections via the water they are transported in and the Artemia themselves. The yeast infection of Chinook salmon in Moore & Strom (2002) led to significant levels of mortality (34.5% compared to 4.3%), but was easily fixable by improving handling procedures.
Attempts at hand raising brine shrimp
It is hypothesised that brine shrimp can be raised by hand, at home, based on pre-existing examples.
Methods:
Initially, online research from tropical fish hobbyist forums, where there are numerous discussion about raising brine shrimp for feed, as well as pages such as (1) and (2)
Three different containers were used and several different feed types were planned. The first two containers were 1.5 litre drink bottles, sawn off about 1/3 of the way from the base. They used filtered water from a tropical fish tank. A small aquarium thermometer recorded the temperatures of each batch.
Bottle 1 was an interim experiment while the sealant was drying on Bottle 2. It was a test of naturally growing algal feed. A lettuce leaf was placed in the saline water and left in sunlight for a week before adding the brine shrimp, to allow algae to grow in the water.
Bottle 2 was turned upside down, and a hole was drilled through the lid. A piece of one centimetre plastic tubing was passed through and glued in place with waterproof sealant. After it had dried, and airstone was attached to the inner end of the tube and the bottle was filled with 1L saline water. An air pump was attached to the other end of the tube, and the bottle was propped up inside and insulating styrofoam case (See Figure 1).
Figure 1: Bottle 2 hatchery (Steede, Nyon (n.d.) How to set up a Brine Shrimp hatchery http://www.fryangle.com/Members%20Articles/Brine%20Shrimp.html)
A small glass aquarium tank was used for the third batch. It used to host plants and small fish, and had to be washed clean of gravel, old water and mud. This was filled with 10 litres of tap water and heated with an aquarium heated. The airstone and air pump were recycled from Bottle 2. Feed was a combination of the supplied mix and Brewer’s Yeast.
Results:
Bottle 1 was initially most successful, with continual issues with temperature. The eggs were very slow to hatch, and had to be placed next to an oil heater in an enclosed space under a desk in order to retain enough heat to reach above 20 C due to poor insulation of the building. This meant that they were frequently disturbed by being kicked over, the cat attempting to sit next to the heater, and by the heater being turned off. The high power bill and inconvenient location made this method highly unsuitable. Despite this, a small number of brine shrimp in this container lasted the longest, although that may be due to staggered hatching events.
The brine shrimp appeared to thrive on the algal growth in the water, but died after being left without heat for several hours. Water quality was not as much of an issue with the algal diet, but the design of the bottle meant that it could not be changed easily.
The brine shrimp in Bottle 2 did not hatch after four days, and the temperature stayed at 15ºC. The unhatched eggs were added to the tank, where they then hatched.
The 10L tank was initially the most successful. A small aquarium heater could safely be added, and there was enough water for the airstone to keep the water moving without bubbling too violently. The brine shrimp in this tank hatched in large numbers (estimated 90+% success rate) and survived approximately four days before dying en masse.
Discussion
As none of the brine shrimp made it to adulthood, there were clearly significant issues with the experiments. A number of them are easy to identify as likely causes, specifically temperature, salinity and water quality. It has been found that both temperature and salinity have independent significant effects (at the 99% level) on time to 50% maturity, batch size and number, fecundity, and generation times as well as the lengths of gestation and reproductive life (Wear et al., 1986) All of these concerns are applicable, scaled up, to commercial aquaculture production. It was also difficult occasionally to count the surviving brine shrimp as they were too small to focus on easily. This means that survival times are estimates only. The complete failure of Bottle 2 is most likely because the bottle could not be kept warm enough during winter. Had the shrimp hatched, this design would have been the easiest to feed and clean.
Different containers had different problems, and while the larger tank appeared to allow a higher proportion of the shrimp to live past the two-day mark, it was also much more resource intensive. The bottles were also slightly tricky to set up as the sealant required several days of drying time and came unstuck easily when adding the airstone inside. Equipment quickly became expensive, and budgetary concerns meant that buying several airstones and heaters to test different flows and sizes, or various feeds, was not possible. The tank was borrowed, as was the tubing and sealant glue.
Salinity
Salinity reduces growth and combination of temperature and salinity are the most important factors deciding mortality and growth rates (Figueiredo et al., 2009). The ideal salinity level for Artemia is 30-35psu. Salinity in this experiment was calibrated using an optical refractometer and recommendations from other sources and was approximately 32 psu. It is unlikely this was the issue as Artemia can thrive in a wide range of salinities, and would not have survived even the short time they did in water that was too far out of their tolerance levels. However, the large amount of water and salt needed for the 10L tank meant that supplies of salt were insufficient for regular water changes.
Water quality
For the bottles, previously filtered water could be taken from fish tanks, but for the 10L straight tap water had to be used. Artemia are sensitive to water quality and it is possible this affected them. They shed their skins as they grow, and this needs to be cleared out – water quality can deteriorate within a week or less. Changing the water was extremely difficult for the small tank, especially once the salt ran out.
Feed
Artemia require particulate foods and feed on algae in the wild. Because of the difficulty keeping the shrimp alive, measuring the effects of different feeds was not feasible or reliable. Their maternal supply of food ensures that most of the shrimp survived the first couple of days. For Bottle 1, the algae in the water appeared to be sufficient. For the tank, too much feed led to deteriorating water quality, which contributed to the failure of one batch. Possible feeds include any non-dissolving particulate matter, such as yeast, whey, wheat flour, dried algae, soybean powder, fish meal and egg yolk (Wikihow, n.d.;) and it is possible to create special feeds (e.g. Bill "Pegasus NZ", n.d.).
Temperature
Temperature is one of the major factors in mortality and growth rates (Figueiredo et al., 2009). It was found that brine shrimp have a required hatching temperature of about 25ºC and usually hatch within 24 hours after adding the eggs to salt water. Maintaining this temperature was the major problem, as the ambient temperature was around 15ºC during daytime, and lower at night. Plastic bottles are difficult to heat and insulate safely, especially in winter and it had an obvious and immediate effect on the survival of the shrimp, with delayed hatching times at colder temperatures.
Oxygen levels and aeration
Strong aeration is also very important, for both oxygen levels and habitat. Brine shrimp can swallow small bubbles forcing them to float (Bischof, n.d.), and will sink without light to attract them or strong turbulence (Wikihow, n.d.).
Bottle 1 did not have an air supply, but possibly the turbulence from being repeatedly kicked or knocked over supplied the shrimp with enough oxygen. The low level of surviving water meant that a greater proportion of the water was in contact with air, which probably also helped with oxygen levels.
The air supply from the airstone was also much too strong when used in Bottle 2 and pushed all the eggs over a centimetre above the water level. It was ideal in the tank, but the brine shrimp tended to get trapped in corners.
pH
While brine shrimp prefer a pH of around 8.0 (Bischof, n.d.) there was no way to test this. Had it been testable, it could have been corrected using baking soda
Lighting
Light levels may have had an effect, as Bottle 1 was kept in near-darkness, while the other two methods were on natural day-night lighting (as recommended by Wikihow, n.d.). Brine shrimp are attracted to light, which meant that they could be attracted to one end by shining a torch, making it easier to change the water. It also means they can expend too much energy trying to reach bright lights (Bischof, n.d.)
Different authors recommend either light or dark (Bill "Pegasus NZ", n.d.), but this contradiction was unable to be tested properly due to the short lifespans of the shrimp – and the lack of spare lamps to put near the bottles (although this would also have provided an inefficient additional source of heat and could be worth investigating).
Conclusion
While brine shrimp can be raised by hobbyists, and are in widespread production, they require a careful set-up and some experience. There are advanced set-ups of increasing scale available to investigate, but each hobby breeder appears to have a different method. They are a very important part of commercial aquaculture feed, and there is ongoing research into improving the consistency of supply and nutritional value.
References
Bill "Pegasus NZ" (n.d.) Raising And Growing Large Brine Shrimp. Retrieved from http://www.aquarticles.com/articles/management/Pegasus_Brine_Shrimp.htmlBischof, B. (n.d.) How to Raise Brine Shrimp. Retrieved from http://www.petplace.com/fish/how-to-raise-brine-shrimp/page1.aspx Figueiredo, J., van Woesik, R., Lin, J. & Narciso, L. (2009). Artemia franciscana enrichment model -- How to keep them small, rich and alive? Aquaculture, 294( 3-4): 212-220KS@Lilly.com (1995) Artemia (Brine Shrimp) FAQ 1.1. Retrieved from http://web.cecs.pdx.edu/~davidr/discus/articles/artemia.htmlLavens, P. & Sorgeloos, P. (2000). The history, present status and prospects of the availability of Artemia cysts for aquaculture. Aquaculture, 181: 397–403
Lavens, P. & Sorgeloos, P. (2000) The history, present status and prospects of the availability of Artemia cysts for aquaculture. Aquaculture, 181: 397–403
Léger, P. & Sorgeloos, P. (1992). Optimized feeding regimes in shrimp hatcheries. In: Fast, A.W., Lester, L.J. (Eds.). Marine Shrimp Culture: Principles and Practices. Elsevier, New York, pp. 225–244.
Lenz, P.H. (1987). Ecological studies on Artemia: a review. In: Sorgeloos, P., Bengston, D.A., Declier, W., Jaspers, E. (Eds.), Artemia Research and Its Application. Ecology, Culturing, Use in Aquaculture, vol. 3. Universa Press, Wetteren, Belgium, pp. 5 –18.
Persoone, G. & Sorgeloos, P. (1980). General aspects of ecology and biogeography of Artemia. In: Persoone, G., Sorgeloos, P., Roels, O., Jaspers, E. (Eds.), The Brine Shrimps Artemia. Ecology, Culturing, Use in Aquaculture, vol. 3. Universa Press, Wetteren, Belgium, pp. 3– 24.
Ritar, A. J., Dunstan, G. A., Nelson, M. M., Brown, M. R., Nichols, P.D. Thomas, C. W., Smith, E. G.,
Crear, B. J. & Kolkovski, S. (2004). Nutritional and bacterial profiles of juvenile Artemia fed different
enrichments and during starvation, Aquaculture, 239(1-4): 351-373Steede, Nyon (n.d.) How to set up a Brine Shrimp hatchery. Retrieved from http://www.fryangle.com/Members%20Articles/Brine%20Shrimp.html)
Wear, R.G., Haslett, S.J. & Alexander, N. L. (1986). Effects of temperature and salinity on the biology of Artemia fransiscana Kellogg from Lake Grassmere, New Zealand. 2. Maturation, fecundity, and generation times, Journal of Experimental Marine Biology and Ecology, 98(1-2): 167-183
Zmora, O., Avital, E. & Gordin, H. (2002). Results of an attempt for mass production of Artemia in extensive ponds. Aquaculture, 213: 395–400
No comments:
Post a Comment
Leave me a comment