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Discovering brine shrimp and their parasites
Photo: Gergana Vasileva © 2008
Photo: Green et al., 2009)
Background: Brine shrimp Artemia franciscana are an integral component of the Great Salt Lake (GSL) ecosystem (USGS, 2007). The lake is an important destination for many species of migratory shore birds including: Wilson’s phalarope and the eared grebe. The birds use the GLS as a resting station during their migration, however, other birds also use the lake as nesting site where they raise their young (Andres et al., 2006). The migratory birds that visit the GSL could be infected with cestode (tapeworm) parasites. Parasites are organisms that exploit their host for resources. In our case, the definitive hosts are migratory birds, and the parasites are the tapeworms. The infected birds release tapeworm eggs into the environment in their excrement where the brine shrimp become infected with them. The brine shrimp are intermediate hosts – a host required for parasite development– for tapeworm parasites (Figure 1). When brine shrimp are infected, they appear dark red in color (figure 2.) (Green et al., 2006). Naïve birds, birds without tapeworm infection, become infected when they consume infected brine shrimp. This successfully completes the life cycle of the parasite.
Figure 1. Microscopic view of tapeworm parasite inside brine shrimp gut. Lower panel is at a higher magnification. Photo from: Brine Shrimp lab, Dr. John F Cavitt 2010. Weber State University
Figure 2. Infected brine shrimp (red color) with other uninfected shrimps for comparison. Picture from Green et al., (2009)
Directions:
1. Students will collect 1 liter of water from the Great Salt Lake (3 times).
2. Students will use a small metal filter to isolate the shrimp from the liter of water.
3. Students will count the number of brine shrimp isolated in each of the three samples
and calculate the average number of shrimp per liter.
a. Note the total number of brine shrimp that have red bellies to greyish bellies.
4. Squish a few red-‐bellied brine shrimp on a slide and observe using a field microscope.
Data collection: Average # brine shrimp per liter of water # Infected brine shrimp # Uninfected brine shrimp Prevalence of infection (%) (# infected/# uninfected) %100 Draw how an infected brine shrimp looks under the microscope in the box below
Questions: 1. What percentage of the brine shrimps is infected?
2. How many shrimp would you have if you collected 6,000 liters of water?
3. How many infected shrimp would you have if you collected 6,000 liters of water?
4. Construct a graph showing the relationship between the number of brine shrimp and the volume of water collected. On the same graph show the relationship between the number of infected brine shrimp and the volume of water collected.
Dimensional Analysis Imagine you are harvesting brine shrimp and you find an area on the lake 1000 m2 in area where the concentration of brine shrimp is the same as the area you sampled.
5. If you can only harvest brine shrimp down to a depth of 10 cm, determine the number of brine shrimp you can harvest in that area.
10 cm = 1 dm; 1 L = 1 dm3; 1 m = 10 dm; 1 m2 = 100 dm2
6. Determine the number of tons of brine shrimp the 1000 m2 area will produce. 1 brine shrimp = 15 micrograms; 1 microgram = 10-‐6 g; 1 L = 1 dm3; 1 m = 10 dm.
7. Determine the number of tones of infected brine shrimp the 1000 m2 area will
produce.
Model tapeworm life cycle as it passes from host to host: Key words (must use to describe life cycle)= intermediate host, definitive host, parasite egg, parasite larva, parasite adult, transmission.
References: Andres B, Clay R, Duncan C. (2006) Shorebird species of conservation concern in the western hemisphere. Western Hemisphere Shorebird Reserve Network.
Cavitt, JF. (2010) Ecology and Natural History of the Great Salt Lake. Retrieved October 21, 11http://faculty.weber.edu/jcavitt/NaturalHistoryGSL/Brine%20Shrimp%20Lab%20.pdf Sánchez MI, Georgiev BB, Nikolov PN, Vasileva GP, Green AJ (2006) Red and transparent brine shrimps (Artemia parthenogenetica): a comparative study of their cestode infections. Parasitology Research. 100: 111-‐14
Sánchez MI, Hortas F, Figuerola J, Green AJ (2009) Colour-‐Based Predation of Parasitized Prey by Shorebirds. Ethiology. 115: 196-‐200
USGS Water Science Center. 2009. Brine Shrimp and Ecology of Great Salt Lake. Retreived October 21, 11, from http://ut.water.usgs.gov.