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The infaunal trophic index (iti): its suitability for marine environmental monitoring

Maurer, Don, Nguyen, Hai, Robertson, George, Gerlinger, Tom
Ecological applications 1999 v.9 no.2 pp. 699-713
benthic organisms, environmental monitoring, fauna, geochemistry, invertebrates, models, particle size, seawater, sediments, wastewater, water quality, California
Macrobenthic invertebrate data from the San Pedro Shelf, California, were used to evaluate the Infaunal Trophic Index (ITI). The ITI is a numerical representation of the distribution of dominant feeding groups of benthic fauna that has been used to quantitatively model community response to organic material in the water column and/or substratum. Although ITI has been applied to various monitoring studies in the Southern California Bight and elsewhere and is used as a regulatory tool in management decisions, the index has not received detailed scrutiny. Long‐term (1977–1993) benthic infauna data and associated sediment geochemistry (particle size, organic and inorganic contaminants) were used to examine variation in ITI. Results indicated that ITI was affected by water depth, granulometry, distance from an outfall of wastewater to the ocean, year and season, and numerically important species. Variation in ITI feeding groups was also affected by year, season, and station. We argue for a more critical application of ITI in regulatory protocols for management decisions in ocean water quality.