Habitat Fragmentation and Its Effects on Aquatic Biodiversity and Ecosystem Services

Abstract

Habitat fragmentation is understood to be one of the key drivers of the erosion of biodiversity and functioning in riverine, estuarine, and marine networks throughout the world. Anthropogenic structures (dams, water control structures, coastal development), along with physical restructuring and spatial rearrangement, disconnect pathways of migratory movement, modify the natural hydrological processes, and cause the isolation of ecological communities. In this paper, the impact on ecological functioning and composition caused by fragmentation is systematically examined through an analysis of multi-regional data from highly fragmented and unfragmented reference basins for over two decades. Species richness, genetic diversity, and the relative abundance of migratory fauna were structurally assessed while the functional components of nutrient retention efficiency and biomass yield were functionally assessed. There was a clear linkage between loss of connectivity and loss in structural and functional components; greatly fragmented networks displayed marked decreased migratory organism populations, loss of function of ecosystem services were exacerbated with reduced connectivity, resulting in compromises of critical services such as the provision of clean water, production of artisan fisheries, sediment retention and carbon storage, which in turn impact both ecosystem integrity and human well-being. Management intervention strategies designed to reduce impacts associated with habitat fragmentation are tested, including the establishment of fish passage, barrier removal, and ecological corridor network design. The use of connectivity parameters integrated into a regional context is proposed as the key for restoration of biological structure and function and sustainable delivery of ecosystem services.