The Infaunal Trophic Index (ITI): Its suitability for marine environmentalmonitoring

Macrobenthic invertebrate data from the San Pedro Shelf, California, were u sed to evaluate the Infaunal Trophic Index (ITI). The ITI is a numerical re presentation of the distribution of dominant feeding groups of benthic faun a that has been used to quantitatively model community response to organic material in the water column and/or substratum. Although ITI has been appli ed to various monitoring studies in the Southern California Eight and elsew here and is used as a regulatory tool in management decisions, the index ha s not received detailed scrutiny. Long-term (1977-1993) benthic infauna dat a and associated sediment geochemistry (particle size, organic and inorgani c contaminants) were used to examine variation in ITI. Results indicated that ITI was affected by water depth, granulometry, dista nce from an outfall of wastewater to the ocean, year and season, and numeri cally important species. Variation in ITI feeding groups was also affected by year, season, and station. We argue for a more critical application of I TI in regulatory protocols for management decisions in ocean water quality.