During a routine shoreline assessment, what type of evidence indicates pollution?

The presence of unusual debris is a strong indicator of pollution during a shoreline assessment because it often signifies that contaminants have entered the environment. This debris can include items such as plastic waste, discarded materials, or chemical containers that are not typically found in a clean or healthy habitat. Such evidence suggests that human activities or environmental mishaps are impacting the shoreline, possibly leading to ecological harm.

In contrast, high insect activity may indicate healthy environmental conditions in some cases, as insects can thrive in various ecosystems. Clear water without sheen could suggest good water quality since sheen often indicates the presence of oil or other contaminants. A lack of visitors on the shore does not inherently indicate pollution; it could simply reflect seasonal patterns, time of day, or weather conditions. Therefore, unusual debris stands out as the most direct evidence of pollution in this context.