RESUMO
The purpose of this study is to analyze the habitat factors (environmental variables) affecting dry-season creek fish, and evaluate habitat biodiversity index (HBI) in dry-season creeks. This research determined HBI formula by 133 study sites in the creek flows in seven rivers in Taiwan from 2007 to 2008. This research considered 10 habitat factors: water depth, width, length, pH, electrical conductivity, temperature, current velocity, rainfall, elevation, and substrate diversity. Using the principal component analysis (PCA), varimax rotated factor analysis (FA), and the simultaneous regression in product-exponential model (PEM), fish total numbers and HBI were formulated by these 10 habitat factors. Pearson's correlation coefficient matrix and three-factor loading plots reported that current flow velocity, rainfall, and elevation affected on fish numbers similarly; besides, water length (logarithmic) and width (logarithmic) had the positive and similar influences in fish numbers. Habitat evaluation levels were classified six groups, namely, excellent habitat, very good habitat, good habitat, fair habitat, poor habitat, and then very poor habitat. In brief, HBI was reasonable and calculated simply by 10 environmental variables of fish habitats. The results of this study can be applied extensively to evaluate the conditions of fish habitats in dry-season creeks for habitat recovery projects.
