Assessing ecological health in areas with limited data by using biological traits.

A multitude of biotic indices that represent environmental status have been developed over the past decades making status comparisons difficult. However, transferring an existing index to a new region can be problematic due to differing stressors, ecosystem components and lack of knowledge on regional species sensitivities. Here we assess whether calculating species sensitivities to specific stressors based on biological traits offers a solution. We use biological traits of macrofaunal species to assess sensitivity to suspended sediment concentrations and calculated the Benthic Quality Index (BQI) at 47 sites across a suspended sediment gradient. This trait-based modification of the BQI was well correlated (0.82) to suspended sediment. Problems previously highlighted, relating to trait plasticity and differential weightings of indifferent and beneficial species, were investigated but did not strongly affect results. A trait-based approach has the additional benefit that the data could be easily converted to evaluate ecosystem function.