Daphnia Research Paper

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

The Artemia franciscana can survive in extreme conditions of salinity, water depth, and temperature (Biology 108 laboratory manual, 2010), but do A. franciscana prefer these conditions or do they simply cope with their surroundings? This experiment explored the extent of the A. franciscanas preference towards three major stimuli: light, temperature, and acidity. A. franciscana are able to endure extreme temperature ranges from 6 ̊ C to 40 ̊ C, however since their optimal temperature for breeding is about room temperature it can be inferred that the A. franciscana will prefer this over other temperatures (Al Dhaheri and Drew, 2003). This is much the same in regards to acidity as Artemia franciscana, in general thrive in

Competition determines survival of the fittest. The larger plankton eat larger particles, therefore making themselves thrive, and the smaller planktonic herbivores were extinguished from the specific lake ecosystem. When the plankton are being heavily hunted, the smaller thrive. The small plankton tend to succeed in the general plankton population because they are effective when collecting their food, and they have lower metabolic rates, requiring them to eat less. An equation was devised to represent this scenario. “The food collecting surfaces are proportional to the square of some characteristic linear dimension, such as body length, in Crystal Lake, for example, the body length of Daphnia catawba is about four times that of Bosmina longirostris, so that the filtering area of the Daphnia is about 16 times larger than that of the

The following was the procedure used by the team that introduced chemicals into the environment of the Daphnia. First a zero reading was taken before any chemicals were introduced. The zero reading was an observation of the Daphnia’s heart rate before any substances were administered. All fluids were drawn off the slide using the corner of a Kimwipe. Then two drops of two percent alcohol solution were dropped onto the Daphnia. After a minute a heart rate reading was taken. The same procedure, including using the Kimwipe to draw off previous solution, was then used with four, six, eight, and ten percent solutions. A heart rate reading was taken after each solution was introduced.

Investigating the Effect of Alcohol on Heartbeat of Daphnia Daphnia are the organisms that are involved in this experiment to find out what effect alcohol has on their heartbeat. It is easy to study the effects of alcohol on the heart of Daphnia as the organ can be easily seen through the transparent body of Daphnia. The number of heartbeats may be counted before submersion in alcohol and after submersion in alcohol to investigate the effect of alcohol. Daphnia belong to the Phylum Arthropoda and are Branchiopoda which belong to the class, Crustacea. Daphnia are invertebrates and also have an exoskeleton, jointed appendages, a dorsal heart and open blood system.

Daphnia are small multicellular organisms, also known as the water flea (even though they are not technically a flea); they are characterized by a modified antennae used for movement, legs used for collecting food by creating a current bringing in food material to their digestive tract, they also collect food using their legs for filter feeding. (Russell, 2013) Daphnia are crustaceans, ranging around 3 mm in size, which commonly inhabit aquatic environments including lakes, ponds, and streams. (Russell, 2013) Daphnia can almost be found in any still standing water body.

The population dynamics of Daphnia magna are observed under three different conditions; low, medium, and high density. The effects of different population densities on the survivorship and reproduction of Daphnia are observed over a two-week period within a lab environment. Over the two week period, the numbers of parent Daphnia alive and dead are recorded daily, along with the amount of offspring produced each day. From the main parameter investigated, the net reproductive rate, the results of the experiment support that higher densities result in less successful reproduction and decreased fecundity. Values for the instantaneous growth rate of the populations also suggests that low and medium density populations allow for

The concentration of solutes in the bodily fluids of most marine invertebrates is roughly isosmotic to their environment (Raven, 2008). Because there is no osmotic gradient there is no tendency for the net diffusion of water away from the animal’s cells to occur. When a change in salinity occurs some organisms have the ability to maintain a constant internal homeostasis despite these external changes and are known as osmoregulators (Oxford, 2008). Other animals lack this ability and as such are called osmoconformers; their internal osmolarity matches that of their

Based on our collaborative data from BI107 lab sections (2016), compared to the starting population, Blepharisma americana, Paramecium caudatum, Euplotes, and Vorticella’s average population size increased in pH conditions 7.0, 5.5, 4.5 and 3.5 (Figure 1). The reason for the ciliates to have a much higher average population size compared to the starting population is because they had the opportunity to reproduce for a week. All four ciliates had the lowest average populations at the pH condition 3.5 and the average population sizes of Euplotes and P. caudatum decreased as the pH levels decreased, implying that an acidic environment is not beneficial for their survival (Figure 1). This supports our hypothesis that a decrease in pH conditions leads to the decrease in average population size. Our results agree with Tremaine and Mills’s (1991) data, which suggests acidification decreased

Halophiles are adaptive by two strategies that include strategies to survive with the osmotic pressure that made by the high NaCl concentration of the normal environments they inhabit (Madigan, M.T.1999, Oren, A, 2002). Other strategy is accumulating of inorganic ions in the cytoplasm (K+, Na+, Cl-) that is in some extremely halophilic bacteria and balance the osmotic pressure of the medium, they have specific proteins which are able to be stable and active in the salty condition. In contrast, moderate halophiles have other strategies to accumulate high amounts of specific organic osmolytes in the cytoplasm, that function as osmoprotectants, which provide osmotic balance and it has not any interfering with the normal metabolism of the cell

When placed in a larger flask, the Danio rerio will consume more oxygen and increase their metabolic rate, because the more they are able to actively swim around, the more water will be continuously pumping into its mouth and across their gills. In the experiment, the amount of oxygen consumption was measured over a 30 minute time period by a Logger Pro instrument. Four different flask sizes were used to change the environment of each zebrafish. By manipulating the size of flask, the experiment was able to study how each environment around the zebrafish affected its metabolic rate. The total amount of oxygen consumed during the experiment was calculated through the difference of oxygen present in the closed system at the beginning and end of the experiment. The metabolic rate was calculated with respect to each individual zebrafish.

The results found that sea stars were negatively effected in growth rate by low pH, even lower in high temperature. Mussel growth rate was positively affected by low pH, however there was no response to high temperatures. Predation of sea stars on muscles decreased in lower pH by 50%. The overall effect shows that muscles perform better at the lower pH compared to the sea stars. Another study was done by Ferrari, M. C. O et al. (2015) which studied the effect of stressors, CO2 levels and temperature, on the predatory prey encounters in reef communities. Their method was to put 6 prey and one predator into 4 different treatments for 22 hours and record how many prey survived this was repeated 2 times for each of the 4 treatments. What the results found was that when both stressors were high, high CO2 and high temperature, the predation rate increased from 30% to 70%. Prey selection changed when it was either high CO2 or high temperature but when the stressors were together the prey selection was equal. Risk taking behaviour was also seen to increase during both stressors. A study was performed by Clements, J. C. et

The aim of the experiment was to determine whether P. lurca is an osmoconformer and U. coarctata is an osmoregulator with the varying salinity levels within the environment they live and the data achieved proved this hypothesis to be true. The data implies that P. lurca maintains a relatively close ionic concentration to that of it’s surrounding environment. This clearly shows that this organism is an osmoconformer. On the other hand, the data also suggests that U. coarctata is an osmoconformer because it’s extracellular fluid maintains the same ionic concentration while the environmental concentration changes (Graph 1). It is evident that the organism changes from osmoconforming to osmoregulating due to the concentrations, or it could not handle the low salinity levels within that environment.

Marine fish sustain an ionic equilibrium with seawater to keep their plasma around 350 mOsm/kg. The gills remove excess salts from the body (Evans et al., 2005), a process that indirectly causes water loss driven by the dehydrating effect of salinity. Therefore, water replacement by drinking becomes of absolute importance to sustain ion regulation (Fuentes and Eddy, 1997a). In addition to regulation by endocrine and environmental factors of the amount of water ingested (Fuentes et al., 1996; Fuentes and Eddy, 1997a; Fuentes and Eddy, 1997b; Guerreiro et al., 2004; Guerreiro et al., 2001), the processing of imbibed fluid has major impact in fish ion regulation. Ingested water is first processed in the esophagus where it undergoes selective

It is required by the Federal Insecticide, Fungicide and Rodenticide Act (7 USCS 136, et seq.) and the Toxic Substance Control Act (15 USCS 2601) to use a model organism to test the effects of a crop additive. Daphnids are typical model species used for aquatic toxicity studies (Jaafarzadeh et al., 2013). Daphnids are a vital part of the aquatic food chain as they are primary consumers (Lovern and Klaper, 2006); therefore, any disruption to their livelihood could have a dramatic effect on the ecosystem.