the impact of whaling on the ocean carbon cycle why bigger was better捕鲸在海洋碳循环的影响更大的更好的原因.pdf

The Impact of Whaling on the Ocean Carbon Cycle: Why Bigger Was Better 1,2 3 1,2 2 Andrew J. Pershing *, Line B. Christensen , Nicholas R. Record , Graham D. Sherwood , Peter B. Stetson1,2 1 School of Marine Sciences, University of Maine, Orono, Maine, United States of America, 2 Gulf of Maine Research Institute, Portland, Maine, United States of America, 3 Fisheries Centre, University of British Columbia, Vancouver, British Columbia, Canada Abstract Background: Humans have reduced the abundance of many large marine vertebrates, including whales, large fish, and sharks, to only a small percentage of their pre-exploitation levels. Industrial fishing and whaling also tended to preferentially harvest the largest species and largest individuals within a population. We consider the consequences of removing these animals on the ocean’s ability to store carbon. Methodology/Principal Findings: Because body size is critical to our arguments, our analysis focuses on populations of baleen whales. Using reconstructions of pre-whaling and modern abundances, we consider the impact of whaling on the amount of carbon stored in living whales and on the amount of carbon exported to the deep sea by sinking whale carcasses. Populations of large baleen whales now store 9.1 6106 tons less carbon than before whaling. Some of the lost storage has been offset by increases in smaller competitors; however, due to the relative metabolic efficiency of larger organisms, a shift toward smaller animals could decrease the total community biomass by 30% or more. Because of their large size and few predators, whales and other large marine vertebrates can efficiently export carbon from the surface waters to the deep se