Environmental variables used in the analysis, assigned main variables groups and corresponding descriptive values.

Asterisks indicate aggregated variables derived by pooling multiple subcategories (e.g. %mud, %clay and %silt was summed up to %SuSo, soft substrates).星号标注的变量为通过合并多个子类别得到的聚合变量：例如将泥粒占比（%mud）、黏土占比（%clay）与粉砂占比（%silt）汇总为软基质（soft substrates）占比%SuSo。