Why are there fewer phytoplankton in the mesopelagic zone relative to the epipelagic zone?
lower light levels
lower oxygen levels
lower nutrient levels
lower water temperature

Ascientist is designing an investigation to study the impact of invasive bird populations on local, native bird populations at backyard bird feeders. what population is most likely to be a control group for the investigation? amount of food number of bird feeders invasive bird populations local backyard birdfeeders without food