Assessment of the State of Ichthyofauna from Danube River – Caleia Branch, Romania: A Sustainable Development Context

Abstract

Evaluating the state of ichthyofauna at both the Lower Danube level and at the national level contains knowledge gaps regarding species dynamics, with the most complex studies regarding species composition being undertaken more than 50 years ago. Over time, the Danube River - an important navigation route that connects Western Europe with Asia - has suffered a series of anthropogenic interventions that led to river discharge regularization, interruptions of longitudinal/latitudinal connectivity and reductions in floodplain area. These anthropogenic activities may negatively impact suitable fish habitats leading to demographical effects. The Danube is regarded as a river with high species richness that provides a source of income for the local population by the practice of commercial fishing. The area of interest for this study was selected taking into account the fact that, in the last decade, it was subject to hydrotechnical works that aim to redistribute the river discharge to improve navigation conditions. The ichthyofauna population dynamics is analyzed using an 8 year-long dataset that includes baseline data before the project started and a monitoring period after the project ended. The results indicate the presence of 38 fish species (excluding anadromous fish species – sturgeons and shads). The identified fish species are classified in two categories: 1) species of commercial interest and 2) species of Community interest. This study provides evidence that the high mobility capacity of the fish species is the main factor affecting species dynamics as support of the national efforts in action to stop the degradation of aquatic habitats and biodiversity, in response to goal 15 “Life Earth” of the UN 2030 AGENDA for sustainable development.