Passage:
For decades, marine biologists viewed whales primarily as consumers within the oceanic food web. However, recent ecological research has revealed that baleen whales play a critical role in fertilizing the upper layers of the ocean through a process known as the "whale pump." These massive mammals feed on nutrient-rich krill in the deep ocean, but because the extreme hydrostatic pressure at depth prevents them from defecating there, they return to the sunlit photic zone to release their fecal plumes. These plumes are rich in limiting nutrients, particularly iron and nitrogen. The sudden influx of iron in these nutrient-starved surface waters triggers massive blooms of phytoplankton—microscopic marine plants that form the base of the ocean's food chain. As the phytoplankton population swells, it absorbs vast quantities of carbon dioxide from the atmosphere through photosynthesis. When these phytoplankton eventually die, a portion of them sinks to the abyssal depths, effectively sequestering carbon on the ocean floor for centuries. Consequently, the decline in whale populations due to historic whaling directly reduced the ocean's capacity to absorb carbon dioxide, demonstrating how a disruption in one part of a biological sequence can precipitate far-reaching atmospheric changes.
Based on the passage, arrange the events in the "whale pump" sequence to construct the step-by-step causal chain linking whale feeding habits to the long-term storage of atmospheric carbon.
- 1Whales consume nutrient-rich krill in the deep layers of the ocean.
- 2Whales ascend to release nutrient-dense fecal plumes in the photic zone.
- 3Phytoplankton populations undergo rapid growth and massive blooms.
- 4Microscopic marine plants absorb carbon dioxide via photosynthesis.
- 5Dying organisms descend to the abyssal depths of the ocean floor.