The effect of iron concentration on ​Euglena gracilis growth rate

Abstract

Euglena gracilis ​is a multi-flagellate microalgae found in most freshwater systems that forms the basis of the system’s food web (Maier & Simenstad, 2009). Increased industrialization has led to more iron leaching into the water systems which can affect ​E.gracilis ​growth positively or negatively depending on the concentration (Olaveson, &Nalewajko, 2000). We tested how iron concentration would affect the growth rate of ​E.gracilis​, hypothesizing that increasing the concentration would increase the growth rate. We grew ​E. gracilis ​samples in growth media with 3 different concentrations of iron added: 7.5μM, 15μM, and 30 μM for two weeks. We calculated the number of cells in each flask aftereach day using a haemocytometer. After analyzing our data using a one way ANOVA test ata 95% confidence level, we obtained a P-value of 0.28 indicating that we do not have enough evidence to reject the null hypothesis which states that there is no difference in growth ratebetween iron concentrations. The growth rates did not show significant differences betweeniron concentrations. These findings offer a starting point for more comprehensive investigations into the effect iron concentrations have on how ​E. gracilis ​change morphologically and how their interactions with other primary producers change.