10.3 Recommendation

Clearly the operational taxonomic level for environ¬mental impact studies is another factor to be considered when planning such a survey, along with decisions about the number of stations to be sampled, number of replicates, types of statistical analysis to be employed etc. The choice will depend on several factors, particularly the time, manpower and expertise available and the extent to which that component of the biota being studied is known to be robust to taxonomic aggregation, for the type of statistical analysis being employed, and the type of perturbation expected. Thus, it is difficult to give general recommendations and each case must be treated on its individual merits. However, for routine monitoring of organic enrichment situations using macrobenthos, one can by now be rather certain that family level analysis will be perfectly adequate. Also, for the free-living meiofauna, there are by now many examples where multivariate analysis of genus-level information is indistinguishable from that for species, and broadly similar results have been found now for a wide range of faunal groups. The topic is returned to in Chapter 16.