n the early 1980s, NOAA scientist Dr. Jeffrey Polovina and his colleagues at the National Marine Fisheries Service, Honolulu Laboratory, developed an innovative marine ecosystem model known as ECOPATH. Named to convey its focus on ecological pathways, it was the first model to apply a type of statistics called “path analysis” to the field of marine ecology. The model’s simplicity and its ability to accurately identify ecological relationships have revolutionized scientists’ ability worldwide to understand complex marine ecosystems.
Ecologists use path models to estimate the direction and strength of all factors that influence the way ecosystems function. The original ECOPATH model described energy flow through the coral reef food web. Starting at the top of the food chain, scientists tracked tiger sharks to determine what and how much they consumed. They extended their observations to other members of the food chain all the way down to algae, simple plants known as primary producers in the parlance of ecological science. Path models allow scientists to calculate direct and indirect effects from a multitude of ecosystem components, providing them with the first means to model an ecosystem’s true complexity.
