Starting at the top of the food web, the researchers gathered information about what tiger sharks were eating. Polovina’s original goal with Ecopath was to better understand the coral reef ecosystem in the French Frigate Shoals, the largest atoll in the Northwestern Hawaiian Islands. Unlike existing models at the time, Ecopath was able to represent complex ecosystems with minimal equations, computing power and start-up data. When Polovina first developed Ecopath in the early ’80s, scientists and policy makers were exploring new ways to describe and manage ecosystems, including the effects of fisheries and other environmental pressures. The essential demand for balance helps to reveal gaps in the data or the need to better understand the predator-prey relationships taking place in an ecosystem. Thanks to its simplicity, the model’s data requirements are often available from existing monitoring studies, fishery records and research involving consumption rates and diet compositions. Since time and space are not factors in the mass-balance equations, Ecopath is considered a static model. The basic Ecopath model works for any undetermined time period, provided the interspecies relationships remain valid. The equations include factors to account for other mass changes, such as animals coming into or leaving the system - including the effects of human fishing and death from disease. Individual growth and population expansion among predator species must be balanced with mortality among the prey species, even as many predators are prey for other animals. Predator-prey relationships are represented by equations that calculate the transfer of mass/energy from one group to another with no net loss. The key to the Ecopath model is to account for total biomass within an ecosystem by organizing all the various species into groups of similar nature. By 2020, about 8,000 researchers had used the software in more than 170 countries, according to the Ecopath support network.įrench Frigate Shoals in Hawaii is home to a wide variety of fish, shown here above a patch of reef 80 feet deep. In 2007, when celebrating the 200 th anniversary of the Coast and Geodetic Survey, the National Oceanic and Atmospheric Administration declared Ecopath one of the 10 greatest accomplishments by agency scientists, along with climate modeling, global positioning systems (GPS) and discovery of the ozone hole. Since then, this food-web model has been expanded, refined and applied to ecosystems throughout the world, including Puget Sound. In the early 1980s, NOAA scientist Jeffrey Polovina and fellow researchers at the National Marine Fisheries Service in Hawaii developed what they called the Ecopath model, designed to describe the flow of energy through a food web.
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