Analyzing algal bloom within False Bay through cultivation of Ulva spp. in experimental settings

Abstract

False Bay, San Juan Island experiences a bloom of the green algae Ulva spp. During the summer. The large abundance of Ulva spp. That subsequently washes up on the upper shore deigns to decay and subsequently produces a pungent smell. This smell is noticeable from multiple kilometers away, leading to numerous complaints from local inhabitants. However, in Friday Harbor, despite being on same island, there seems to be less algae accumulated near its shore. To analyze what could have caused False Bay’s algal accumulation near its shore, I conducted an experiment to explore unique condition in False Bay that causes the phenomenon. In this research, water condition, including factors outside of chemicals, was tested. Ulva spp. samples gathered in False Bay was cut to even size and were cultivated in water from False Bay, Friday Harbor, and artificially made seawater in experimental settings. During the first trial, I found that there is no significant difference in amount of growth in Ulva spp. samples cultured in False Bay and Friday Harbor’s seawater. However, both had significantly larger growth rate compared to artificial seawater,. During the second trial of the experiment, many Ulva spp. lost pigemtation, which caused weakening of structure and stunted growth among the samples. Trial 2 showed no significant difference in growth rate based on source of seawater. It is concluded that while nutrient within False Bay aids in the growth of Ulva spp., it may be not the driving factor of algal blooms during summer seasons. More research is needed to find the possible cause of algal accumulation in False Bay’s shore and understand its nature, because while heavy accumulation Ulva spp. can reduce the abundance of sediment species, its decomposition provides detritus for various animals in False Bay such as clams.