The effect of nutrition on the activity of Artemia franciscana
Intro:
In most ecosystems, the availability of nutrition is the most limiting factor of population growth and activity (Fábregas, 1997). If there is a lack of food resources in a community or a lack of certain specific dietary requirements, then the physiology of that community and it’s fecundity should be noticeably affected. Nutrients like carbohydrates, proteins and fats are carried around the body, along with oxygen from the air, through the circulatory system throughout which metabolism uses oxygen to convert these nutrients into ATP for energy use (Johnson 1980). When an organism is experiencing starvation it is not receiving enough nutrients to support the normal rate of ATP and hence energy production and so slows all metabolic processes in the body in order to preserve energy for survival (Jacobstein and Gerken, 1989). With the decreased rate of metabolism there is less demand for oxygen and so the rate of oxygen consumption and overall activity of the organism slows with the rate of metabolism (Fábregas, 1998).
The study of the effect of specific diets on the activity of Artemia has been the subject of several experiments (Sick, 1976; Johnson, 1980; Fábregas et al ., 1996, 1998). Nutrition treatment has been shown to affect the activity rates of populations of Artemia. This experiment, through feeding two populations of Artemia different levels of algae and fish food for three weeks, we investigated the effect of nutrition on the activity of Artemia. The low nutrition population was fed algae on daily basis providing largely carbohydrates whereas the high nutrition population was fed daily ten times the amount of algae as the low nutrition population plus fish food which gave them an extra source of protein and nitrogen. During the experiment the length-specific oxygen consumption rate of the different populations was recorded and a video of each population was used on the computers along with software to measure the velocity of each population to determine the effect of diet on activity.
The population on a higher diet have more carbohydrates, protein and nitrogen
to fuel ATP and energy production and hence should have a higher average velocity and a higher average length-specific oxygen consumption rate. Methods:
A pipette was used to place 7 – 13 Artemia, that had been maintained on a high-energy diet, into a glass vial, ¾ full with water which was placed uncapped into the vial holder in a 250C water bath. After 5 minutes the glass vials were sealed with caps under the water and after a further 5 minutes the vials were taken to an oxygen meter. The oxygen concentration and elapsed time was measured, the vial was returned and the process was repeated 5 times. The animals were then transferred with a pipette to the dissecting scope where their length was individually measured with a ruler. The Artemia were returned to the recovery container, the empty glass was rinsed and the experiment was repeated for the population maintained on a low-energy diet.
Tracker software was used to track an individual’s movement across 30 frames, which was averaged and repeated 5 times at each. The average length-specific oxygen consumption rate and the average velocity of the populations at different temperatures was analysed to assess activity of the populations using column graphs, tables and a t-test comparison in Excel to determine if any significant data was collected.
Results:
The effect of starvation on the rate of oxygen consumption depended on the population tested. In Figure 1 the rate of oxygen consumption increased with increased nutrition in diet. The length specific oxygen consumption was 0.014 ± 0.004 µmol/mm/h at low nutrition levels and 0.019 ± 0.005 µmol/mm/h at high nutrition levels so the average is higher for the higher nutrition level (t=2.464, df=18, p=0.024).
The effect of starvation on the velocity of the Artemia depended on the population tested. In Table 1 the velocity increased with increased nutrition in diet as expected. The velocity was 6.85 ± 3.292 mm/s at low
nutrition levels and 16.04 ± 3.882 mm/s at high nutrition levels so the average is higher for the higher nutrition level (t=7.578, df=106, p=1.39E-11).
Table 1: Class average results of the velocity (mm/s) of the Artemia with differing diets including standard deviation results
Velocity (mm/s)
Low Nutrition
High Nutrition
Average
6.85
16.04
Standard Deviation
3.29
8.39
Discussion:
The results of the first experiment supported the hypothesis that the average length-specific oxygen consumption rate would decrease with a lack of nutrition in the diet of Artemia. We observed the Artemia on a low nutrition diet had a lower average rate of oxygen consumption. We predicted and observed the Artemia on a high nutrition diet had a significantly higher rate of oxygen consumption (see Figure 1). This correlated with the results from other similar experiments (Jacobstein 1989, Johnson 1980, Smith 2010). These experiments all contain consistent results, as the methodology in each of the experiments was consistent. There were some unexpected results, but this is most probably due to human error; the absorbance levels were probably read wrong. The results of the second experiment also supported the hypothesis that the average velocity of the population would decrease with a lack of nutrition in the diet of Artemia. We observed the Artemia on a low nutrition diet had a lower average velocity. We predicted and observed the Artemia on a high nutrition diet had a significantly higher rate of average velocity (see Table 1). This correlated with other similar experiments in
the field (Fábregas 1996, Jacobstein 1989, Johnson 1980, Sick 1976, Smith 2010). These experiments all contain consistent results, as the methodology in each of the experiments was consistent. Again there were some unexpected results, but this is most probably due to human error; the velocity may have been read wrong. All life requires food and so all organisms, unicellular and multicellular alike, have created ways to recognise, respond to and survive in times of scarcity. If a cell is deprived of nutrients it cannot convert these into ATP and energy and so the carbon requirements and its structural components get recycled in an attempt to survive (Brown, Schwalbach and Smith, 1991). Oxygen is used in Artemia for all metabolic activity including the conversion of nutrients to ATP for energy. When there is a scarcity of food, metabolism slows down to preserve energy for survival and so oxygen consumption and the activity of the organism is in turn decreased (Smith, 2010).
As predicted in the hypothesis, the population on a higher diet had more carbohydrates, protein and nitrogen to fuel ATP and energy production and hence were shown to have a higher average velocity and a higher average length-specific oxygen consumption rate. Reference List:
Articles:
G. C. Brown, M. S. Schwalbach, D. P. Smith (1991) “Control of respiration and ATP synthesis in mammalian mitochondria and cells”. Biochemical Journal. Volume 2: 12
J. A. Fábregas, E. M. Otero, B. Cordero and M. Patiño (1996) “Tetraselmis suecica cultured in different nutrient concentrations varies in nutritional value to Artemia.” Aquaculture paper 143:189-201.
J. A. Fábregas, E. M. Otero, B. Cordero, M. Patiño and B.O. Arredondo-Vega (1998) “Modification of the nutritive value of Phaeodactylum tricornutum for Artemia sp. in semi-continuous cultures.” Aquaculture paper 169:170-173.
M. D. Jacobstein, T. A. Gerken (1989) “Oxygen deprivation and early
myocardial contractile failure: A reassessment of the possible role of adenosine triphosphate”. American Journal of Cardiology. Volume 2: 2, 3
D.A. Johnson (1980) “Evaluation of various diets for optimal growth and survival of selected life stages of Artemia.” 170-181.
L.V. Sick (1976) “Nutritional effect of five species of marine algae on the growth, development and survival of the brine shrimp Artemia salina.” Volume 35: 67-72.
E. W. Smith (2010) “Effect of Starvation on the Endocytic Pathway in Dictyostelium Cells”. American Society for Microbiology. Volume 8: 5, 6
