Daphnia Research Paper

Title: Physiological Changes in the Heart Rate of Daphnia magna When Exposed to Stimulants (Caffeine and Alcohol).

The Daphnia is commonly referred to as the water flea and has been under research by scientists for over a century. Daphnia can be located in and around permanent bodies of water. Daphnia, although can be found in any water, are usually found in freshwater lakes especially near ponds and high vegetation areas. Daphnia are too small to live in strong currents so they branch to ponds and small lakes where they live off plankton.

Daphnia, also known as water fleas, are small crustaceans about 1mm-5mm long and are part of the freshwater zooplankton (Ebert 2005, Hutchinson 2005 & Clifford 1991). Daphnia can be found in most fresh water habitats such as freshwater springs, ponds and reservoirs and are the predominant food for planktivorous fish. Dapnia are ‘filter feeders’ meaning they feed on small particles suspended in the water which can include algae. It has been found that daphnia tend to migrate to the upper parts of the water at night and return to the lower parts of the water in the day to hide from predators (Ebert 2005) (Hutchinson 2005). Daphnia can reproduce through sexual reproduction and also asexual

Referring to the experiment`s hypotheses that the A. franciscana prefers light, temperatures between 20-24 ̊ C, and a basic (pH 8) environment; the results regarding the first treatment, light, were initially vague. According to the experiment results, the A. franciscana did not show a clear preference towards light or dark because both sections contained high concentrations of them; the A. franciscana also strayed from the uncovered section. Several factors may shed light on the results such as the A. franciscanas physical appearance; they possess three light-sensitive eyes that can adjust to both low and high light intensities (Fox, 2001). This means that although they may prefer light they can survive in darker habitats as well; relating back to the experiment the A. franciscana may have been content with wherever they were, resulting in limited movement.

Studies of Daphnia presented information which elluded to the idea that Daphnia would react to environmental pollutants within a relatively short timeframe; therefore, a lab was constructed to find the effects of copper sulfate in a Daphnia’s system. Before beginning, the hypothesis was gathered: if the concentrations of copper sulfate in the water are high, then the Daphnia would be afflicted with symptoms associated with physical decline. Daphnia, known as water fleas, are small crustaceans who get their common name from their jerky movements. The organisms reside within lakes and ponds often in limestone-based areas found all over the world. Daphnia consume algae, specifically the free-living green type, yeasts, and bacteria; therefore,

The additional species, Daphnia Pulex are a derivative from Daphnia Magna, which can be in located rain filled tire ruts and any stable body of water. These daphnia are established in fresh water and maintain the highest concentrations of daphnia compared to other species can be found in lakes and ponds. Daphnia magna is a water flea dependent on environmental conditions to breed and survive. Conditions such as temperature, salinity and oxygen levels can be detrimental to the lifespan of these organisms (Elenbaas, 2013. Within their existing environment daphnia consume algae, bacteria and detritus; it is this continual uptake of these organisms, which maintains the food chains integrity. Daphnia also host a number of bacteria, fungi, nematodes,

Daphnia are normally used to test potentially harmful substances in water supplies, and are easy to handle and monitor. This experiment was designed around this fact,

Daphnia are Crustacea. Crustacea are animals that have ten legs, four antenna and two main body parts. Most live under water. Some examples of Crustaceas are Crayfish, Shrimp, and Crabs. Daphnia are filter feeders. They eat small particles of algae and bacteria. Some are carnivores and eat other water fleas. Daphnia live in fresh water places such as ponds and lakes. They are found living in the vegetation or near the bottom of the body of water.

Daphnia magna, arthropods of the subphylum Crustacea, are widely used during laboratory experiments because they are very sensitive to many environmental parameters including temperature and chemical contaminants (Cornell, 2009). In this experiment, Daphnia magna were tested under different experimental factors, including temperature changes and exposure to different chemical, in order to observe the effect of environmental conditions on their heart rate.

Table 1 (Figure 3) shows that the control is the lowest in heart rate, from there the heartbeat goes up when the daphnia are exposed to sugar. The difference between the control and the rest of the tests is very large. Although the data is very spread, the averages clearly show a significant difference between the results. The control group clearly showed that the heart rate of a daphnia magna is lower than the other two tests. The solution using the juice had more effect on the heart rate of a daphnia magna than a sugar solution and the control. The two sets of data that were taken with the daphnia exposed to the solutions were very close and shows that both have similar effects on the heart rate, they both increase the BPM of the daphnia

Daphnia are important because they are important to the food chain in these aquatic habitats; they feed on algae, algae is a producer- it converts sun energy into food, and larger animals, consumers or predators, such as small fish feed on Daphnia, thereby passing this energy to them. (Russell, 2013) Therefore, studying Daphnia is important in the understanding of not only the ecology and behaviour of Daphnia, but also other members of the same food web, its consumers, the fish. Daphnia increase in abundance in summer months,

Their bodies are encased by an uncalcified shell, carapace, and they can reach lengths of 5mm with a kidney bean shape (Ebert, 2005). The Daphnia magna live in mostly freshwater environments, but can live in certain brackish water areas. In comparing males and females the males have smaller body sizes, larger antennas a modified post-abdomen (Ebert, 2005). The Daphnia magna are good test subjects to assess the effects of the plant defense compounds of caffeine and Kava-kava, as they are easy to care for, inexpensive, and the effects of the compound are easily noted through looking at the heart rate of the organism under a microscope. This experiment required the use of a two-tailed t-test to determine whether there was a difference in heart of the Daphnia magna before and after the plant defensive compounds (caffeine and Kava-kava) were introduced. This test also helps to see if the difference in the test is statistically significant, which determines if the results obtained occurred by chance. A t-value is obtained to get the probability value and as the t-value increases it “signifies a larger meaningful difference between the two groups” (Blanar, 2017) and as it decreases the opposite happens. If a t-value is smaller than the t-critical value the null hypothesis is accepted, but if the obtained t-value is larger than the t-critical value the null hypothesis is rejected. A p-value is also important for this experiment, as it is the probability the null hypothesis is correct. The null hypothesis for this experiment was that there was no difference in the Daphnia magna heart rate after the plant defense compounds (caffeine and Kava-kava) were added compared to before, while the alternative hypothesis generated was that there is a difference in the Daphnia magna heart rate after the plant defense compounds (caffeine and Kava-kava) were added compared

Daphnia are minute crustaceans and they live in fresh and salt water all around the world (these daphnia’s will be sourced from fresh-water). Daphnia’s are arthropods, which means they belong to the family, which includes crustaceans and insects. They usually reach a maximum of 0.5 millimeters. Although daphnia’s are very small, they are vital to the cleanliness of their environment, as they filter the water by consuming bacteria. Scientists often use daphnia’s in experiments to gain more information of the human circulatory and nervous system. As daphnia are located in fresh water, there is a real risk of fertiliser leaking from households into creeks and rivers. This task will prove the danger of this for wildlife and the effect it has

For the most part, goldfish exposed to ambient light experienced a higher change in oxygen consumption than fishes that were exposed to dark light. However, because the p-value for our experiment, 0.211, fell below the recommended 0.05 threshold, we were unable to report a statistically significant difference in the metabolic rates of goldfish exposed to different lighting conditions (ambient vs. dark). Because it is likely that the differences in average oxygen consumption between the two conditions (exposure to ambient light vs dark light) were a result of chance, we were unable to reject the null hypothesis stating that there is no statistically significant relationship between the metabolic rate of goldfish, and its exposure to light. With this being said, previous studies have reported exposure to light to be an important factor governing the biological cycle of fish (Choi et al. 2017; Bromage et al.

with is a crustacean called the Daphnia. Later in this report I will attempt to