fertilizers have a positive impact on algae growth & time contains salt from cropland ->  fertilizers in the runoff from cropland have a positive impact on algae growth  fertilizers in the runoff from cropland have a positive impact on algae growth & conclusions is a mean of vertebrates & if something has a positive impact on an organism 's growth then that something increases the population of that organism -> fertilizers in the runoff from the cropland can increase the population of algae fertilizers in the runoff from the cropland can increase the population of algae  cheetahs in the liquids from the cropland can decrease the equal of insect & a cropland is a kind of farm -> fertilizers in the runoff from the farm can increase the population of algae