Survey of Algal Drift Composition and Distribution at Cattle Point: A Comparison of Two Sampling Methods

Abstract

Algal wrack is an integral ecological engineer and food source for many terrestrial and marine organisms. We surveyed the wrack line on a sand and gravel substrate at Cattle Point on San Juan Island Washington. We addressed four questions: (1) What is the algal composition of the wrack? (2) Is there spatial separation between algal groups? (3) What is the effect of the sampling methods? (4) Is there a spatially associated size difference? We employed two different sampling methods, cookie cutter and point contact method. We hypothesized that there would be a difference in both algal composition and size across the beach. We also hypothesized that the two different survey methods would yield different results. We analyzed the samples in the lab, sorting them into algal groups labeled kelp, other non-kelp brown algae, red blades, filamentous/branched reds, seagrass, and green algae. We also took size measurements of the point contact samples. We found that overall algal composition was consistent between both sampling methods with kelp being the most abundant and in descending order other non-kelp browns, filamentous/branched reds, red blades, seagrass, and greens being the least numerous. Although we did not find that there were any detectable patterns in algal composition or size when looking at the individual sections. There was also no consistency comparing the sampling methods within the individual sections. This suggests that there may not be any difference in algal group distribution along the wrack line or any spatial relation to size differences.