A stochastic model for seagrass (Zostera muelleri) in Port Phillip Bay, Victoria, Australia

Recently, there have been attempts to identify a set of key environmental i ndicators for Victoria's marine and coastal environments. The recommendatio n that seagrass density and abundance be used as indicators requires that t he effects on seagrass resulting from changes in the physical environment b e predictable. This paper presents a stochastic population model for Zoster a muelleri in Port Phillip Bay, Victoria. Building the model identified a n umber of issues that relate to constructing models for modular organisms. O f particular importance are the assumptions made when devising demographic structure and modelling complex population ecology in data poor environment s. The project has provided a preliminary framework for the evaluation of p otential environmental indicators and the monitoring programs developed for them. Using the probability of falling below a range of population densiti es, we were able to specify a background risk against which impacts may be measured. In this case, there was a 50% chance that the population density would fall below 230 individuals per m(2) at least once in the next 20 year s. Simulations representing the impacts of turbidity plumes are presented. (C) 1999 Elsevier Science B.V. All rights reserved.