During certain times of the year, the gulf of mexico experiences hypoxic conditions (oxygen depletion). this is known as a dead zone. what is responsible for the emergence of dead zones in the gulf of mexico? 1points a fertilizer runoff from agriculture has polluted the water so much that there is more chemicals dissolved in the water than oxygen. b algal blooms from fertilizer runoff eventually die and decompose. when they decompose, the decomposers use much of the oxygen in the water. c high levels of trash pollution absorb dissolved oxygen in the water creating depleted oxygen levels. d the water that feeds into the gulf from the mississippi river has less oxygen in it than the water in the gulf, resulting in areas with less oxygen.