Undergraduate Reasearch

Rising carbon dioxide is causing ocean temperatures to increase, which can stress marine organisms. The invasive European green crab (*Carcinus maenas*) was studied to determine how it responds to elevated temperatures. Crabs from Stinson Beach were divided into a control group kept at 13°C and an experimental group kept at 23°C for nine weeks. Their body mass was measured throughout the experiment.

The results showed that 92% of crabs exposed to 23°C lost body mass, compared with about 54% of the control group. This suggests that prolonged exposure to higher temperatures increases physiological stress and may negatively affect growth. As ocean temperatures continue to rise, thermal stress could affect both invasive and native crab populations.

The invasive European green crab (Carcinus maenas) is common along the California coast and can be used to study how changes in seawater pH affect marine invertebrates. Crabs collected from Stinson Beach were divided into control and experimental groups and monitored for nine weeks. The experimental group was exposed to lower pH levels (6.4–6.9), while the control group remained at normal seawater pH (8.1–8.2). Crabs were weighed to track changes in body mass.

Although the experimental crabs showed some gains and losses in mass, there was no overall difference between the groups. This suggests the crabs may be able to adjust their exoskeleton mineral composition and tolerate changes in pH. These findings indicate that European green crabs may have a strong physiological tolerance to changing seawater conditions, which could help them survive as ocean chemistry changes.