Spatial Dynamics of Melanotaenia arfakensis Community Structure in the Api and Asiti Rivers: Implications for In Situ Conservation of Endemic Fishes in Kebar-Tambrauw, Southwest Papua Province, Indonesia

Abstract

Papua, Indonesia, is home to high freshwater biodiversity, including endemic species such as Melanotaenia arfakensis, which is found exclusively in the Kebar highlands. This study aims to analyze fish community structure and the impact of invasive species in two major river systems, Api and Asiti Rivers, using a spatial approach across upstream, midstream, and downstream segments. The methods employed include ichthyological surveys, measurement of environmental parameters, and ecological indices such as diversity (H'), evenness (E), and dominance (C). Results show that the abundance of M. arfakensis drastically decreases from upstream to downstream in both rivers, while invasive species such as Oreochromis mossambicus and Puntius spp. significantly increase in downstream segments. The highest diversity index was recorded in the downstream section of Sungai Api, though it was accompanied by high dominance of invasive species, indicating ecological disruption. These findings underscore the importance of a zonation-based conservation approach, focusing on upstream habitat protection, midstream ecosystem rehabilitation, and invasive species control downstream. This strategy should be integrated with community participation and ongoing ecological monitoring to support in-situ conservation and the overall preservation of freshwater biodiversity in Papua, Indonesia.