The Effects of Population Density on the Reproduction and Survival of Daphnia Magna

Phytoplankton are microscopic photosynthesising organisms which live in water. In favourable environmental conditions they have a very high rate of reproduction. They are eaten by microscopic animals called zooplankton. In an investigation, samples of water were removed from a lake at intervals over a twelve-month period and the biomasses of these organisms were determined. The results are shown in the graph.

Data for Trews Weir clearly implies that dace in this area do not have usual food available in this area compared to others along the river so it is essential to look for other food items to populate this region. This explains why they do not have a growth rate that is in line with the other sampling site (figure 9).

Limulus polyphemus spend their adult life either in estuaries or on the continental shelf during the winter months (ASMFC 2015). It is during the spring in which the horseshoe crabs migrate back to sandy beaches to spawn. Typically, spawning takes places during high tide with a new or full moon but is much higher during nights with a full moon. . During spawning the males grasp onto the females before heading to shore. Once the pair is on the beach, the female will then dig multiple nests or clusters and deposit her eggs while the male fertilizes them (National Wildlife Federation 2015). The areas chosen for egg laying are typically within bays and coves, which protects the nests from wave energy (ASMFC 2015). Each year a female will lay about 90,000 eggs in different clusters. These eggs play the most vital ecological role for migrating shorebirds as an energy source. Without areas such as the Delaware Bay, where the largest spawning population in the world is found, the migratory birds such as the Red Knot would not have a rest area with the appropriate amount of energy resources to refuel their

For this experiment the independent variable is the crayfish and elodea while the dependent variable is the respiration rate measured in NaOH. The elodea and crayfish were placed into two different graduated cylinder containing 30ml and the volume displacement were than recorded. Once finished measuring, three beakers were obtained, labeled and 100ml of tap water was added to each beaker. The control group is beaker 3. The beaker containing elodea was completely covered in foil and placed into a dark cabinet to avoid photosynthesis from happening for 15 minutes. After 15 minutes, the crayfish and elodea were taken out and placed back into their tanks. Four drops of the pH indicator phenolphthalein were added to each beaker. NaOH was dropped

Competition is a limiting factor that can determine a species' carrying capacity. When population increase, individuals start competing for food, shelter, and the most suitable mates. While the stronger individuals tend to survive, the weaker individuals begin to die off because of insufficient resources for everyone in the community. Competition can lower birthrates and increase death rates. When two different species live in the same area, they compete for resources in that environment and typically one species is eliminated by the other. The population will reach its carrying capacity when competition reduces the size of the population to what the environment can support.

The dependent variable in the investigation was the 9 day algal growth in each solution. The growth of algae is gauged by the change in the turbidity of the algal solutions from the initial and final day of data collection. Turbidity is a measure of the loss of water transparency due to the presence of particles in the water. One cause of turbidity is the presence of algae in water. In this experiment, the main cause of the increase in turbidity is the increase

The first tank is our control group. We added 1000 Periwinkles into the control tank and recorded the shell thickness for each individual Periwinkle in the population. Carcinus were not included in the control tank. The Periwinkles could reproduce without any environmental pressures caused by the Carcinus. The Periwinkles were left to reproduce over the span of five generations. In the fifth generations of Periwinkles, we recorded the shell

Data collected over a period of two weeks indicates that sodium chloride prohibits Ankistrodesmus growth since optical density measurements of each test tube were recorded in a table as well as graph (Figures 1 and 2). The data shown in this table and graph show that although the Ankistrodesmus algae grew slightly at some points, overall it decreased in optical density, which means sodium chloride prevented its growth. This conclusion can also be drawn from the average net gain/losses of optical densities table and graph. The data collected indicates that the Ankistrodesmus grew more in the 50% sodium chloride solution, which was treatment group 3 (Figure 4). However, this cannot be acknowledged since Day 14’s test tube readings were taken using another group’s setup. Consequently, only readings from Day 0 and Day 7 are accurate and usable. Even though treatment group 3’s data is unreliable it’s only one result and accounting this group still leaves treatment groups 1 and 2. By comparing treatment groups 1 and 2 to the control group one can easily conclude that the optical densities of the two treatment groups decrease (Figures 3 and 4). This indicates that as the concentrations of sodium chloride increases then the overall growth of algae decreases. Therefore, one can conclude that from the readings sodium chloride prohibits Ankistrodesmus algae

Over all, Tubes 1, 2, and 3 showed increase in the growth of the Ankistrodesmus algae. These tubes all contained salt solution and this, compared to the control, resulted in higher ankistrodesmus growth levels.

We hypothesized that there is no correlation between nutrient availability and the maximum growth rate and the carrying capacity. Based on our results about we concluded to reject our hypothesis since nutrient availability does affect growth rate and carrying capacity of the species.

In this experimentation my lab partner and I decided to conduct an experiment to determine if species Porcellio scaber and Armadillidium vulgare were attracted to 10% sucrose solution rather than deionized water. To start, we initially obtained a container that consisted of a mixture of P. scaber and A. vulgare species. A total of 16 random isopods were gathered to run our control group with deionized water. Two circular, pre-cut, filter papers were moistened with deionized water and used to line the compartments of the choice chamber, where the 16 isopods were equally divided into 8 and randomly placed in each chamber. The 16 isopods were then observed for a total of 3 trials with a duration time of 10 minutes per trial period. After we gathered

control by thermal manipulation. Moreover, in Xiphophorus helleri the sex ratio was affected by pH and water

Anadromous fishes reproduce in freshwater then their progeny migrate to the ocean where they grow and mature then return to freshwater to reproduce. These fishes encounter numerous barriers during their freshwater migration. Migration barriers (e.g. dams, water storage projects, irrigation diversions, impassable culverts, etc.) are significant factors affecting most anadromous fish populations. The primary effects of barriers on anadromous fishes are the reduction of their population abundance and productivity through excessive mortality, and reduction in habitat quantity and quality (NMFS, 2008).

The lifespan of Sepia savignyi In the Red Sea and the Gulf of Suez were studied by Ibrahim et al., (1993) reported four age groups for both sexes with mean lengths 10.10, 15, 18.20 and 20.10 for males and 10.35, 16.50, 20.70 and 23.55 for females in the age groups from I to IV, respectively. El-Sherbeny (2009) found that three years for males with mean lengths of 8.26,16.09 and 20.13 cm., and five years for females and sexes combined with mean lengths of 9.05, 16.47, 22.81, 26.14, 28.12 and 8.36, 16.47, 22.81, 26.91, 28.05, respectively. While Mehanna and El-Gammal (2010) revealed two years for males with mean lengths 9.43 and 15.17and four years for females in 10.33,19.41, 24.97, and 27.39 mean lengths respectively. The

Competition in ecosystems has become central to the study of ecology, and has been implicated as a major factor behind the patterns of species abundance and distribution. Though often studied together, abundance and distribution are two distinct designations, abundance being the density of a species in a given area, and the spatial arrangement of that species in an area is referred to as the distribution (Brown, 1984). In ecological terms competition refers to a fight between two organisms, of the same species or different, for a limiting resource, leading often to an adverse effect on one or both organism (Birch, 1957). When one of the organisms in the competition out competes the other for the desired resource this results in a negative