Question

Which of the following observations would indicate that runoff from terrestrial environments is reaching the ocean?

a. Decrease in toxic chemicals
b. Increase in primary consumers
c. Lower levels of carbon dioxide
d. Accelerated growth of algae

Answer 1

The most clear sign of runoff from terrestrial environments reaching the ocean is the accelerated growth of algae, also known as eutrophication, due to nutrients like nitrates and phosphates from fertilizers leading to algal blooms and potential dead zones.

Step-by-step explanation:

Runoff from terrestrial environments reaching the ocean can have several indicators, but the most common and clear sign is the accelerated growth of algae. This phenomenon, often referred to as eutrophication, is primarily due to the runoff containing high amounts of nutrients such as nitrates and phosphates from fertilizers. When these nutrients enter aquatic systems, they fuel the growth of algae and phytoplankton, leading to algal blooms. Such blooms consume oxygen in the water — creating anoxic, or low-oxygen, conditions that can lead to the formation of dead zones where aquatic life cannot survive. Moreover, the primary cause of ocean acidification is atmospheric CO2 dissolving in ocean water, which is a separate concern related to the increasing levels of carbon dioxide in the atmosphere.