|Ecological models for impact evaluation of dredging|
Heip, C.H.R. (1990). Ecological models for impact evaluation of dredging, in: Alzieu, C. et al. (Ed.) Proceedings of the International Seminar on the Environmental Aspects of Dredging Activities Nantes (France), 27 November - 1 December 1989. pp. 205-221
In: Alzieu, C.; Galenne, G. (Ed.) (1990). Proceedings of the International Seminar on the Environmental Aspects of Dredging Activities Nantes (France), 27 November - 1 December 1989[s.n.]: Nantes, more
Models based on academic ecological theory specifically aimed at impact evaluation of dredging on populations and communities in their environment do not exist for the moment. Nevertheless, the very rapid development in theoretical ecological modeling over the last two decades has generated an extremely diverse ensemble of theories on populations and communities. It has become increasingly recognized that perturbations are frequent and natural phenomena that allow persistence of populations on larger spatial and temporal scales. In this view, equilibria do not exist, at least not on the small scale, in patches. Many models point out that extinction on this scale is both natural and frequent. Current efforts to model local, transient dynamics, in patches may well prove to be more realistic than the large ecological models trying to describe the functioning of the whole system. Models of local dynamics will also have to incorporate local history and natural selection. In the absence of theoretical models the impact of dredging on populations and communities is of ten assessed using empirical errors statistical methods. These may serve as descriptions and may generate hypotheses but are usually unable to determine causal relationships and must be supplemented by field or mesocosm experimentation. Often fundamental errors are made in which the basic assumptions to apply statistical procedures for true hypothesis testing are violated. Many monitoring programmes contain fundamental procedural f1aws. A summary is given of the more classical! procedures used, based on changes in abundance, species-abundance relationships, diversity indices, classification and ordination.