Zooplankton Enumeration and Feeding Write Up

Zooplankton Enumeration and Feeding Write Up - Josh Ahn...

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Josh Ahn EEMB 142 CL Paper #1 Zooplankton Enumeration and Feeding Introduction Grazing is an important aspect of both marine and terrestrial ecology that has significant effects on community structure, local environment, primary production, and numerous other variables. Grazing impacts are important in nature because they reveal many ecological processes that are occurring between organisms and their environment. These impacts not only affect the types and densities of the different plants and animals in the community but the physical characteristics of the environment as well (Yang and Dudgeon 2010). Information regarding grazing is absolutely necessary in understanding the flow of material and exchange of energy among trophic levels in aquatic and terrestrial food webs. Thus, studying the different aspects of grazing [including grazing rates and clearance rates] is critical in understanding how different ecosystems function. Grazing rate is a measure of the number of food units that is ingested per animal per unit of time. In marine sciences, clearance rate is a measure of how much water an organism must filter to obtain a given amount of food (Methods in Aquatic Biology). Grazing rates express how much food an organism eats through time while clearance rates reveal how much energy an organism expends in acquiring nutrition. Combined, these rates provide insight into the availability of food at a site and the feeding behaviors
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of the aquatic organisms that inhabit it. For example, a high grazing rate combined with a low clearance rate might indicate that the concentration of prey at a particular location during a particular time is high, allowing the predator to consume large numbers of the prey without having to expend much energy foraging. In contrast, a relatively low grazing rate along with a high clearance rate might suggest low prey concentrations and therefore high energy expense for the predators in the search for food. These are of course just a few of numerous possible explanations regarding these rates, and the actual factors behind the rates will vary among different ecosystems and organisms. This paper will examine the grazing of Chlorella by Daphnia magna in Lake Los Carneros, located in Goleta, California. We conducted laboratory experiments to determine grazing and clearance rates of Daphnia magna on Chlorella as well as the abundance of zooplankton in the lake . This data provides insight on the concentrations of these organisms in the lake as well as the impact of grazing on phytoplankton populations and the relationships between density and grazing rates. Materials and Methods Study Site Lake Los Carneros is located in Goleta, California. The area of this lake is 60000m 2 with a mean depth of 1.5m and a volume of 900000m 3 . Sampling
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Zooplankton Enumeration and Feeding Write Up - Josh Ahn...

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