Professor/ Chairman National Cheng Kung University
The habitats are important for organisms, while the various and suitable habitats are needed in different life stages of organisms. Between different habitats, many paths provide the organisms to move freely, and it is called “habitat connectivity”. Cote et al. (2008) have developed the longitudinal connectivity which was assessed using the Dendritic Connectivity Index for potamodromous species(DCI_p). In this study, the Biodiversity Index (Rodeles et al. 2020) which combined species richness, rarity, and vulnerability was chosen to interpret reach biodiversity. We use Mean Patch Fraction Dimension (MPFD) to represent the habitat quality of the section. To understand how barriers impact the fish passability and longitudinal connectivity in the river, we combine river length, reach biodiversity, and habitat quality as determination parameters, to develop a new index to quantify the longitudinal connectivity. To examine the feasibility of this novel index, we discuss the river connectivity of the Dananbei Stream in Taitung. In order to restore the stream ecological environment and recover habitat connectivity, Taitung Forest District Office started to lower some of the barriers in 2018. Before lowering the barriers, the DCI value was 13.65%, and the CCI value was 37.56%. Based on the results of CCI, after lowering some of the barriers, the DCI value is increased to 23.65%, and the CCI value to 40.13%. The result shows that longitudinal connectivity is significantly affected by the barriers, and lowering the barriers could improve connectivity positively. Based on this study, we learned more about the impact of the low-head dam on fish passability and longitudinal connectivity of the river, and these results can also be used as a reference for river restoration.
