Predictive Index of Biotic Integrity for running waters of Iran

Iran is the second largest country in Southwest Asia and covers multiple ecoregions, different climatic regions, and considerable fish diversity. Man`s activities had profound and usually negative influences on freshwater ecosystems. Current efforts to evaluate effects of man`s activities on aquatic ecosystems have been attempted to use chemical/physical water quality parameters and macroinvertebrates. These indicators do not fully reflect human disturbances, in particular hydromorphological pressures and continuity disruptions. Therefore, in this project we will focus on fish as an additional indicator based on the assumption that human pressures have significant effects on the distributions of fish species and hence alter the composition and structure of fish assemblages. First, we review the fish ecological situation and identify main ecological requirements and guilds of Iranian fish species. We then compile a database of fish species distribution using historic records and reports, maps of species distribution, actual records of species occurrence and actual samplings of fish assemblages. After that we develop country-wide presence/absence models for fish species and ecological guilds for undisturbed reference conditions using environmental factors. In order to analyse the pressure-specific response of fish communities to human alterations, test catchments in different ecoregions are selected. Field samples of fish communities are compared with the expected undisturbed conditions predicted by the reference models using different types of metrics. Finally, responsive metrics are integrated into a multi metric Index of Biotic Integrity for running waters of Iran. This will be the first large scale and country-wide IBI in Asia.

Freshwater ecosystems offer provisioning, regulatory, cultural and supporting services. If ecosystems are degraded, some or all of these services may be lost. Therefore, it is highly necessary to protect, enhance and restore surface waters with the aim of achieving a good ecological status, as e.g. demanded by the EU-Water Framework Directive. Indeed, this project focused on (1) predicting the presence and absence of trout (Salmo trutta) for the whole Iran and (2) on developing fish-based multi-metric assessment indices for cold-water and cyprinid streams in the Iranian southern Caspian Sea basin.Overall, for predicting the presence and absence of brown trout, 1090 sites were investigated. Five different modelling techniques (GAM, GBM, GLM, CTR and RF), summarised in an ensemble forecasting approach, were used to explore the potential distribution of brown trout. The related results deepen the knowledge about distribution patterns of brown trout and give a basic background for the future development of assessment methods for riverine ecosystems in Iran. For developing multi-metric fish indices in cold-water and cyprinid streams, first, various human pressure types related to land use, connectivity, hydrology, morphology, water quality and biology as well as their combinations were investigated in each stream type. According to the results, most sites were affected by land use pressure in both stream types. In addition, only a few sites were affected by single pressure in both stream types while most sites in cold-water streams were affected by double and triple pressures and in cyprinid streams by multiple pressures. Moreover, the differences of fish metrics between reference and impacted sites were quantified for each stream type according to a site-specific modelling approach. In fact, specific statistical models were used to describe metric responses to natural environmental differences in the absence of any human pressures. By including impacted sites, the residual distributions of these models described the response range of each metric to human pressures, independently from natural environmental influence. Finally, to develop a multi-metric fish index of cold-water streams, two fish metrics were selected which showed the best ability to discriminate between impacted and reference sites. In contrast, for the development of a multi-metric fish index for cyprinid streams, seven metrics were considered.The results can be used for further development of a standardised monitoring tool to assess the biological condition as well as the ecological status and trends for streams of Iran and are very important for this bioregion with a complex and diverse geology and climate.