page_title: Ecosystem of the North Pacific Subtropical Gyre
section_title: History of discovery
hierarchical_section_title: Ecosystem of the North Pacific Subtropical Gyre / History of discovery
caption_attribution_description: HMS Challenger (launched 1858)
context_page_description: The North Pacific Subtropical Gyre is the largest contiguous ecosystem on earth. In oceanography, a subtropical gyre is a ring-like system of ocean currents rotating clockwise in the Northern Hemisphere and counterclockwise in the Southern Hemisphere caused by the Coriolis Effect. They generally form in large open ocean areas that lie between land masses.
  The NPSG is the largest of the gyres as well as the largest ecosystem on our planet. Like other subtropical gyres, it has a high-pressure zone in its center. Circulation around the center is clockwise around this high-pressure zone. Subtropical gyres make up 40% of the Earth’s surface and play critical roles in carbon fixation and nutrient cycling. This particular gyre covers most of the Pacific Ocean and comprises four prevailing ocean currents: the North Pacific Current to the north, the California Current to the east, the North Equatorial Current to the south, and the Kuroshio Current to the west. Its large size and distance from shore has caused the NPSG to be poorly sampled and thus poorly understood.
  The life processes in open-ocean ecosystems are a sink for the atmosphere’s increasing CO
  2.
context_section_description: The NPSG is not often sampled because of its distance from the coast and its shortage of marine life. These vast and deep ocean waters, far from the influence of land, have historically been considered the oceanic equivalent of terrestrial deserts, with low standing stocks of biomass and low production rates. This perspective is derived from a dearth of comprehensive investigation of central gyre habitats. Over the past two decades these views have been challenged with a newfound understanding of the dynamics of the NPSG.
  During the early days of marine exploration, HMS Challenger (1872–1876), on its leg from Yokohama to Honolulu, collected plant and animal specimens as well as numerous seawater samples. The goals of this expedition were to determine the chemical composition of seawater and the organic matter in suspension and to study the distribution and abundance of various communities of organisms. The motivation for studying open ocean ecosystems has changed over time, whereas today more modern studies focus on biodiversity and the effects of climate on ecosystem dynamics. Today, the Hawaii Ocean Time-series (HOT) program has assembled the largest and most comprehensive ecological data set for the NPSG and is scheduled to continue to the next millennium.  Programs like HOT have debunked the hypothesis that this ecosystem is static and homogenous, finding that the NPSG exhibits dynamic seasonal patterns separating it from other open ocean systems.
caption: HMS Challenger embarked upon the first global marine research expedition in the 19th century.
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