The researchers studied the distribution of major species in Chinhae Bay from 1987 to 1990. They found that certain polychaetes and molluscs were dominant, with specific species like Lumbrineris longifolia and Paraprionospio pinnata being prevalent. These species had high density in areas with different levels of organic content, suggesting they could indicate pollution levels. Overall, the study showed that certain species were more abundant in specific parts of the bay, depending on the organic content of the sediment.