The effect of fertilizer on the growth rate of the diatom Licmophora abbreviata

Rowan Harris, Geraldine Hernandez, Camille Locas, Callee Yuen


The main objective of this study was to examine the effect that increasing concentrations of liquid fertilizer at 0%, 20%, 40% and 60% has on the organism Licmophora abbreviata, a type of benthic diatom. This allows us to gain a better understanding of the effects of agricultural fertilizer runoffs on rivers, its surrounding environment, and the conditions of the community these microalgae live in. The methods consisted of growing diatoms in the four different concentrations for a period of two weeks, with three replicates per treatment. The diatom growth rate was measured on six different days with a hemocytometer where the change in concentration of cells was determined by counting the number of cells per volume. The significance of the data was analyzed with a one-way ANOVA test. Results show significant evidence to suggest that there is a difference in the growth rate  of diatoms between the 0%, 20%, 40% and 60% environments. The number of cells in the 0% treatment increased with time, analogous to their natural growth in rivers. The 20% , 40% and 60% treatments of  liquid fertilizer, had a negative effect on diatom growth. This is explained by the disturbance the added nutrients from the fertilizer caused on the optimal ratio of nutrients that diatoms need (Danielsson, 2008). Thus, we  conclude that agricultural fertilizer runoffs have a negative effect on the growth rate of the benthic diatom community in rivers. 

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