what is the variable that may change as a result of a change in the variable the experimenter changes

How does upwelling affect coastal fisheries? upwelling damages nutrient supplies at coastal fisheries as the warm, nutrient-rich surface water is replaced by nutrient-poor, cold water. upwelling damages nutrient supplies at coastal fisheries as the cold, nutrient-rich surface water is replaced by nutrient-poor, warm water. upwelling improves the nutrient supply at coastal fisheries as the warm, nutrient-rich surface water replaces the nutrient-poor, cold water. upwelling improves the nutrient supply at coastal fisheries as cold, nutrient-rich water replaces the warm, nutrient-poor surface water.

The earth's oceans are made up of chlorine, and trace elements. a) carbon, oxygen b) oxygen, silicon c) hydrogen, oxygen d) nitrogen, oxygen

Which level of taxonomy has the fewest organisms?