Predictive modelling of freshwater fish as a biomonitoring tool in New Zealand

Abstract

SUMMARY 1. A challenge has been issued to ecologists to find quantitative ecological relationships that have predictive power. A predictive approach has been successful when applied to biomonitoring using stream invertebrates with the River Invertebrate Prediction and Classification System (RIVPACS). This approach, to our knowledge, has not been applied to freshwater fish assemblages. 2. This paper describes the initial results of the application of a regional predictive model of freshwater fish occurrence using 200 reference sites sampled in the Manawatu–Wanganui region of New Zealand over late summer/autumn 2000. In brief (i) sites were classified into biotic groups (ii) the physical and chemical characteristics that best describe variation among these groups were determined and (iii) the relationship between these environmental variables and fish communities was used to predict the fauna expected at a site. 3. Reference sites clustered into six groups based on fish density and community composition. Using 14 physical variables least influenced by human activities, a discriminant model allocated 70% of sites to the correct biological classification group. The variables that best separated the site groups were mainly large‐scale variables including altitude, distance from the coast, lotic ecoregion and map co‐ordinates. 4. The model was further validated by randomly removing 20% of the sites, rebuilding the model and then determining the number of removed sites correctly allocated to their original biotic groups using environmental variables. Using this process 67% of the removed sites were correctly reassigned to the six predetermined groups. 5. A further 30 sites were used to determine the ability of the model to detect anthropogenic impact. The observed over expected taxa (O/E) ratios were significantly lower than the reference site O/E ratios, indicating a response of the fish assemblages to the known stressors.

Complex size-dependent habitat associations in potamodromous fish species

“…This highlights the need to consider the use of different life stages when making spatial distribution assessments that are particularly important from a conservation point of view. Though the large-scale gradient of longitudinal position has been shown to influence fish distribution within river systems elsewhere (Joy and Death 2002;Mugodo et al 2006), other factors were also important in shaping the spatial organisation of species life stages.…”

Intra and inter-annual structure of zooplankton communities in floodplain lakes: a long-term ecological research study

“…This occurs because reservoirs reduce the natural amplitude of water levels variation, consequently changing the dynamics of aquatic communities (Ward & Stanford 1995). The resulting ecological damage may have economic and social impacts in human communities, since recent studies indicated that biodiversity ensures the maintenance of ecosystem processes, buffering the effects of detrimental changes (Galat & Lipkin 2000, Joy & Death 2002, Naeem 2002, Srivastava & Vellend 2005). …”

An expert system based on fish assemblages for evaluating the ecological quality of streams and rivers

“…Oberdorff et al, 2001) as well as neural networks (e.g. Boet and Fuhs, 2000;Joy and Death, 2002;Mastrorillo et al, 1997;Olden and Jackson, 2001;Scardi et al, 2004Scardi et al, , 2005. The expert system we developed, however, goes a step farther, because it leverages an Artificial Intelligence approach in the strictest sense, i.e.…”