Abiotic impacts on spatial and temporal distribution of Corbicula fluminea (Muller, 1774) in the River Minho Estuary, Portugal

1. The non-indigenous species Corbicula flianinea (Muller, 1774) is one of the most invasive bivalves in freshwater ecosystems. This Asian clam was first reported in the River Minho estuary in 1989. After a short period of time, it became the major component of the local benthic fauna in terms of abundance and biomass. 2. In the autumn of 2004 and 2005, spatial and temporal variations in abundance, biomass and population structure of C. fluminea were investigated at 16 sites in the freshwater subtidal area of the River Minho estuary. Mean abundance and biomass per site ranged from 80 to 4185 ind. m(-2) and 8.5 to 465.9 g AFDW m(-2), respectively. 3. The environmental characterization of the area was performed through multivariate analysis, which revealed three distinct areas subjected to different abiotic conditions. C. fluminea population structure is well correlated with these three distinct areas. 4. The combination of several abiotic variables determining C. fluminea biomass distribution was evaluated through a stepwise multiple regression. This model showed that redox potential, nutrient concentrations, hardness, organic matter and sediment characteristics explained almost 60% of the variation in C. fluminea biomass in the freshwater subtidal area of the River Minho estuary (R-2 = 59.3%, F-[9,F-86] = 13.9, p < 0.001). 5. Improved ecological knowledge is essential for future C. fluminea management, in order to protect local habitats and biodiversity, and to reduce the economic impact of this non-indigenous invasive species. Copyright (c) 2007 John Wiley & Sons, Ltd.