Climate change messes with the food chain
Column: How a decline in tiny water-based plants is hurting penguin populations.
Scientists concerned with the biological effects of climate change are focusing on what some call “the grass of the sea.” These are tiny water plants known technically as phytoplankton. Like the green grass on which cattle feed, these little plants are at the base of many food chains in lakes and the ocean. Other tiny animals feed on them and, in turn, become food for larger critters. Knowing how phytoplankton’s abundance is changing in different locations is crucial to understanding what climate change may be doing to life on our planet.
Isolating climate’s role in plankton changes won’t be easy. As a review of the subject earlier this month in Science noted, the tiny plants are buffeted by many factors besides systematic climate change. For example, cleaning up runoff from farms can reduce the nitrogen and phosphorus that feeds plankton blooms. Fishing also can disrupt food chains down to the level where there are fewer grazers that eat the tiny plants.
Martin Montes-Hugo at Rutgers University and colleagues have found 30 years of satellite data and field studies a potent tool for cutting through that complexity. Satellites traced phytoplankton abundance by sensing the green cast of their chlorophyll. The scientists think these data reveal the hand of climate in phytoplankton changes off the western Antarctic Peninsula. They recently explained why in Science.
The data show a 12 percent decline in phytoplankton in the area over the 30-year period. The distribution of the tiny plants has also changed with declines in the northern part of the peninsula and increases to the south. The researchers also noted that the “cold-dry polar-type climate” that once characterized the region is morphing into a “warm-humid sub-Antarctic-type.”