Where will they go? : Cryptomonas erosa vertical distribution in a poorly mixed water column with nutrient and light gradients
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In inland lakes, light and nutrients form gradients within the water column. Mathematical models have been used to show that algae can form thin layers within the water column at some depth to maximize light and nutrient intake. Biomass within the water column creates a shading effect of light. Light decreases exponentially with depth in lakes. Nutrients decrease as algae deplete the resources. Nutrients decrease linearly as depth increases in lakes below the algal layer. Here we aim to prove this theory with a system where nutrients and light are controlled. Five towers with identical light conditions, and varying nutrient concentrations, were built to house the algal species Cryptomonas erosa. We hypothesized that the system with the greatest nutrients available would show a peak in biomass at a shallower point than in the tower with fewer nutrients. In the towers with the greatest nutrient levels, C. erosa formed a layer shallower in the tower than in a tower with fewer nutrients as expected, and it showed a deeper peak in biomass in the system with less nutrients. In all of the systems a surface aggregation was formed. In Towers B, C, D, and E, this surface aggregation had more biomass than other locations in the tower. Growth rates for the C. erosa were extremely low in this experient Future researchers may look into different variables that could have affected this low growth rate, and may decided to use a different algal species. The idea of towers is useful to researchers looking to study algal relationships year round in a laboratory environment.