Document Type

Capstone Project

Degree Name

Bachelor of Science (B.S.)


Science & Environmental Policy


he Giant Kelp, Macrocystis pyrifera is widely harvested in California by removing the uppermost four feet of the canopy. The canopy may be a microhabitat that experiences a water flow regime unique to that portion of the kelp. Plaster of Paris clod balls, which dissolve at different rates under different flow conditions, were used in this study to determine if there was a significant difference in water flow in four microhabitats in Giant Kelp: the holdfast, the stipe, the curve of the stipe immediately below the canopy, and the canopy. Diffusion factors (the ratio of weight loss of plaster in the field to the weight loss of plaster in controlled still water conditions) were calculated for each microhabitat. Paired t-tests were conducted to determine if the diffusion factor at the different microhabitats was significantly different. The statistical tests showed that the diffusion factor of the holdfast is significantly different from the diffusion factors at the other three microhabitats, and since the diffusion factor is directly related to water found to be significantly different from the holdfast and not from the other microhabitats on the kelp. More research needs to be focused on determining whether or not the microhabitats have a significant difference in other environmental characteristics, such as light availability and nutrient delivery. Additionally, research needs to be conducted on the effect of kelp harvesting on the holdfasts.


Capstone Project (B.S.) Earth Systems Science & Policy Institute