Could Limnoperna fortunei be worse than Dreissena polymorpha? Population density and potential impacts

KARATAYEV VADIM; KARATAYEV ALEXANDER; BURLAKOVA, LYUBOV; BOLTOVSKOY DEMETRIO; CATALDO DANIEL

Montreal, Quebec, Canada

Congreso; ICAIS 2009 (16th International Conference on Aquatic Invasive Species); 2009

ICAIS 2009 (16th International Conference on Aquatic Invasive Species)

Could Limnoperna fortunei Be Worse than Dreissena Polymorpha? Population Density and Potential Impacts Alexander Y. Karatayev and Lyubov E. Burlakova Buffalo State College, Great Lakes Center 300 Elmwood Avenue, Buffalo, NY 14222, USA Vadim A. Karatayev City Honors School 186 East North Street, Buffalo, NY 14204, USA Demetrio Boltovskoy and Daniel Cataldo University of Buenos Aires, School of Exact and Natural Sciences, Department of Ecology, Genetics and Evolution C1428EHA Buenos Aires, Argentina The freshwater golden mussel, Limnoperna fortunei (Mytilidea, Bivalvia) is considered to be the most aggressive invader in the southern hemisphere. In late 1980s – early 1990s, Limnoperna invaded South America and has already spread into Argentina, Paraguay, Uruguay, Brazil, and Bolivia, causing significant ecological and economic impacts. In the near future, L. fortunei is very likely to invade North America. Limnoperna fortunei is a suspension feeder and much of its ecosystem effects are due to shifting energy and matter from the water column to benthic communities (benthic pelagic coupling). Therefore, the overall ecosystem effects of Limnoperna will depend on their densities. However, with the exception of isolated records, to date there was no information on the population densities of Limnoperna over large areas. We studied the distribution of L. fortunei across different substrates and depths, and estimated its population density in a waterbody using Río Tercero Reservoir (Córdoba, Argentina) as an example. L. fortunei was found in 57 of the 109 diver-collected samples. Densities and biomass varied significantly with substrate type, being lowest on silt, medium on sandy substrates, and very high on rocks. Rocky and sandy substrates were most common at 4-8.5 m, resulting in the highest densities and biomass of L. fortunei on these depths. Comparison of these data with our previous results on the distribution and density of D. polymorpha in several European lakes, indicates that across all substrates L. fortunei attains substantially higher densities and biomass and will therefore have much stronger impacts on the ecosystems invaded than D. polymorpha. Moreover, because the ecosystem impact of both species is a function of their biomass rather than numerical density, L. fortunei, being significantly larger than D. polymorpha, will reach a higher biomass the zebra mussel, even in situations when both species attain similar densities, and will therefore have stronger ecosystem impacts. In addition, L. fortunei has broader environmental tolerance to high temperatures, low pH, low calcium content, oxygen depletion and water pollution than D. polymorpha. Therefore, L. fortunei may be much more successful than D. polymorpha in regions dominated by acidic, soft and contaminated waters. Although to date D. polymorpha is considered the most aggressive freshwater invader, many waterbodies that are already affected by D. polymorpha may soon host another, even more aggressive invader with much stronger environmental impacts.