Abstract
The Lower Mekong Basin (LMB) is a key biodiversity hotspot. To facilitate conservation and management, we examine mollusc biodiversity patterns and distribution along LMB’s longitudinal gradients, identify environmental drivers, and discuss the importance of these drivers to management. Cluster analysis, redundancy analysis (RDA), and variation partitioning were conducted using mollusc data collected from 63 sampling sites. Results indicated that species diversity is dominated by gastropods (61%) and bivalves (39%) and feeding trait diversity by scrapers (52%) and filter-collectors (37%). Only 48 species (49%) out of 98 taxa have been assessed by the International Union for Conservation of Nature (IUCN) including a growing number of invasive species. The lack of complete, up-to-date information highlights the need for more research on both native and alien species. Cluster analysis revealed a clear mollusc biodiversity structure along the LMB’s longitudinal segments. Diversity was lowest in upstream tributaries, increased in upstream main channels, and was highest in downstream channels and the Mekong delta, the exception being the observed high gastropod abundance in Chi-Mun river mouth and Luang Prabang areas. The RDA and variation partitioning demonstrated that combined physical–chemical and climatic conditions are the key drivers of biodiversity patterns. Given the potential spread of invasive alien species and increasing anthropogenic impacts, further ecological research, regular monitoring, and adaptive management are needed to sustain mollusc biodiversity and associated ecosystem services, which contribute to food security, nutrition, and livelihoods in the LMB.
Highlights
Molluscs are a key component of freshwater ecosystems, contributing to bioturbation and filtration in freshwater lotic and lentic environments [1,2,3]
From 2004 to 2008, molluscs and along with other benthos were sampled at 63 sampling sites in the Lower Mekong Basin (LMB) [25] (Figure 1)
More information is needed on species, family, and order diversity; species functional feeding groups; and conservation status
Summary
Molluscs are a key component of freshwater ecosystems, contributing to bioturbation and filtration in freshwater lotic and lentic environments [1,2,3]. Living molluscs and their dead shells can enhance food availability and provide physical structure for other organisms [4]. Mollusc biodiversity and structural patterns are noticeably influenced by physical–chemical conditions, nutrient availability, and food web dynamics in ecosystems [3]. In tropical and sub-tropical regions, pollution and disturbance, due to agricultural intensification, transportation, and aquaculture, have negatively affected mollusc biodiversity [8,9]. Changes in water flow and sediment types due to anthropogenic influences have affected mollusc distribution and abundance [10,11]
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