What food there is takes the form of bits of organic debris drifting down from the sunlit surface waters, thousands of meters above. In this cold, dark environment, very little food is available. The flat, muddy seafloor at these sites lies between 4,000 and 5,000 meters beneath the ocean surface. The recent paper covers two time-series studies-one at “Station M,” about 220 kilometers off the Central California coast, and a second on the Porcupine Abyssal Plain, several hundred kilometers southwest of Ireland. Based on 18 years of studies, Smith and his coauthors show that such ecosystem changes occur over short time scales of weeks to months, as well as over longer periods of years to decades. However, according to Ken Smith, a marine ecologist at the Monterey Bay Aquarium Research Institute (MBARI) and lead author of the recent PNAS article, changes in the Earth’s climate can cause unexpectedly large changes in deep-sea ecosystems. Historically, many people, including marine scientists, have considered the abyssal plains, more than 2,000 meters below the sea surface, to be relatively isolated and stable ecosystems. Based on long-term studies of two such areas, a new paper in the Proceedings of the National Academy of Sciences (PNAS) shows that animal communities on the abyssal seafloor are affected in a variety of ways by climate change. The vast muddy expanses of the abyssal plains occupy about 60 percent of the Earth’s surface and are important in global carbon cycling. After studying these and other deep-sea animals, Smith’s group has seen their populations change dramatically from one year to another. A deep-sea urchin crawls across the muddy seafloor at Station M, about 220 kilometers off the California coast and 4,000 meters below the sea surface.
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