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Our meta-analysis of 80 published and adequately documented reports on fish responses to suspended sediment in streams and estuaries has yielded six empirical equations that relate biological response to duration of exposure and suspended sediment concentration. These equations answer an important need in fisheries management: quantifying the response of fishes to suspended sediment pollution of streams and estuaries has been difficult historically, and the lack of a reliable metric has hindered assessment for risk and impact for fishes subjected to excess sedimentation. The six equations address various taxonomic groups of lotic, lentic, and estuarine fishes, life stages of species within those groups, and particle sizes of suspended sediments. The equations all have the form z = a + b (logex) + c(logey); z is severity of ill effect, x is duration of exposure (h), y is concentration of suspended sediment (mg SS/L), a is the intercept, and b and c are slope coefficients. The severity of ill effect (z) is delineated semiquantitatively along a 15-point scale on which is superimposed four “decision” categories ranging from no effect through behavioral and sublethal effects to lethal consequences (a category that also includes a range of paralethal effects such as reduced growth rate, reduced fish density, reduced fish population size, and habitat damage). The study also provided best available estimates of the onset of sublethal and lethal effects, and it supported the hypothesis that susceptible individuals are affected by sediment doses (concentration × exposure duration) lower than those at which population responses can be detected. Some species and life stages show “ultrasensitivity” to suspended sediment. When tested against data not included in the analysis, the equations were robust. They demonstrate that meta-analysis can be an important tool in habitat impact assessment.
Newcombe et al. (Fri,) studied this question.