STEP 3b: View Example Graph
This graph was prepared by a marine biologist, and looks much like the graphs you'll prepare as you complete this project. Below is the comparison of rockweed cover at middle elevation unoiled sites and oiled/washed rocky sites, 1989-1996. Washed sites were cleaned by hot-water washing during the months after the spill.
Mean Percent Cover of a 0.25 Square meter Quadrat
Summary of Fucus gardneri Abundance
This graph shows mean percent Fucus gardneri cover of 0.25 square meter quadrat from 1989 to 1996. Abundance is plotted for these categories: oiled/washed and unoiled. The data for oiled/washed sites show a steep decline in cover in 1989 after treatment. Mean abundance of oiled/washed Fucus dropped from a high of 80% cover per quadrat in 1989 to a low of less than 5% in 1990. Abundance then steadily increased to a high of over 60% in 1993. Cover again declined, reaching a low of about 20% in 1995, then increasing to about 35% in 1996.
The abundance of unoiled Fucus fluctuated somewhat during the same period, but gradually decreased from about 70% cover per quadrat in 1989 to just over 30% in 1996. Although the steep decline in Fucus cover in 1989 at oiled/washed sites almost certainly reflects the impact of oil and treatment, the other fluctuations are more difficult to explain. This is true for oiled/washed sites, as well as control sites.