What caused the sea life are amchitka island and shemya island to be different?

The differences in sea life between Amchitka Island and Shemya Island can be attributed to variations in their environmental conditions, such as water temperature, salinity, and nutrient availability. Additionally, the geographical location and oceanic currents surrounding each island influence the distribution of marine species. Historical factors, including human activities and nuclear testing on Amchitka, may have also impacted local ecosystems. Consequently, these factors create distinct habitats that support different marine biodiversity.