Medomak High School Sophomore Anna Weber recently conducted an experiment growing kelp in seawater kept at a variety of different temperatures. She was assisted by Boothbay Sea and Science Executive Director Pauline Dion who provided her with equipment and assisted in the set up of the experiement.
Anna’s findings, reported at the school’s science fair on March 16, found that warmer water impedes the growth of kelp and actually caused it to degrade. Below is her abstract. You can read more about her experiment here.
How water temperature affects kelp’s primary productivity
Climate change has been raising the ocean’s temperature for decades now, impacting many of the plants and animals within the ocean’s ecological communities. This can be more detrimental to some organisms than others, including Laminariales (kelp), which have traits that make them incredibly valuable to aquatic ecosystems. The purpose of this experiment was to see how changing the temperature of the water affects kelp’s ability to photosynthesize and grow. I hypothesized that increased water temperatures would decrease the kelp’s primary productivity and growth rates. In addition, I predicted that the cooler water’s pH levels would increase more than the warmer water’s pH. Different strands of kelp were grown in tanks with varying temperatures. Weekly, the pH, salinity, and temperature of the water were tracked, as well as the length of the kelp. During this experiment, the water’s pH levels did not change as they were expected to, however, the growth rates of the kelp varied greatly. The kelp in cooler water grew up to 25 cm, with an averaged 145% growth rate, and continued to stay healthy. Contrarily, the kelp in the warmest water only reached about 12cm, with an averaged 42% growth rate, and began to disintegrate. Kelp in water just 5°-10°F higher did substantially worse. These findings suggest that as ocean temperatures rise, kelp may struggle to survive. The loss of such an impactful plant could be detrimental to both terrestrial and oceanic environments.