Lentic Community Study

The purpose of this lab was to study a local lake using it as an example of an lentic community. A lentic community is an aquatic community that is comprised of standing water, lake or pond, as opposed to flowing water, river. Samples of both biotic and abiotic factors at the field site were taken. The biotic factors are the living organisms while the abiotic factors are the physical and chemical samples. A plethora of photosynthetic autotrophs and heterotrophs constructed the population of an lentic community which has been observed to have high species diversity (Bicudo and Rodrigues 2001). Autotrophs are organisms that produce their own organic material, which is the foundation of the community, by photosynthesis. Heterotrophs are either …show more content…
The warmer water stays closer to the surface, and the deeper the water goes the cooler the temperature is. This process of layering warmer water on top of the cooler water is known as thermal stratification which begins in Raleigh in the spring and ends in the late fall. Thermal stratification changes between day and night; the energy of the sunlight that was absorbed radiates from the water into the cooler night air which causes the upper layer of the surface to cool. The water becomes denser and sinks below the warmer water in a process call convective mixing. Thermal stratification also is very important in determining the amounts of the dissolved gases such as oxygen and carbon dioxide. Water with higher temperatures has a lower capacity of holding dissolved oxygen and carbon dioxide, and water with lower temperatures has a higher capacity of holding these dissolved gases. The gases are being exchanged between the water and the air during both night and day, but the water is losing more in the day and gaining more at night due to temperature. This results in the concentrations of the gases to come into balance with the air and surface …show more content…
As the process of photosynthesis is being completed, the carbon dioxide is used and oxygen is released which results in more carbon dioxide being dissolved in the water and more oxygen diffused in the air. The production of ATP is known as cellular respiration, and this process uses oxygen and produces carbon dioxide. This process can occur during both night and day which results in an excess of carbon dioxide at night due to the fact photosynthesis halts at night. All of the aforementioned processes collectively determine the dissolved oxygen and carbon dioxide concentrations. Where there is a lack of light, there is a lack of photosynthesis, so the deeper water results in lower dissolved oxygen concentrations. The organisms that live in that water heavily depend on these gases for living, and the availability of them affect the numbers and distribution and organisms in the differing