Mass Mortality of Invasive Snails: Impact of Nutrient Release on Littoral Water Quality

Abstract

Mollusks are the macroinvertebrates most commonly introduced into fresh water. In invaded reservoirs, alien mollusks form a large biomass due to their large size. Climate change, water level regulation, and anthropogenic impacts on the environment lead to the drying up of water bodies and the death of littoral macroinvertebrates. To assess the impact of invasive snail mass mortality on water quality, laboratory experiments on the snail tissue decomposition were performed, the potential release of nutrients into aquatic ecosystems was calculated, and the predicted concentrations of nutrients were verified by field studies. The laboratory experiment showed quick decomposition of the common river snail Viviparus viviparus tissues with release into the environment of ammonium and total phosphorus of 2.72 ± 0.14 mg and 0.10 ± 0.02 mg, respectively, per gram of decomposing tissue. The concentrations of ammonium, nitrates, and total phosphorus at the site of snail death reached 2.70 ± 0.10, 3.13 ± 0.38 and 0.30 ± 0.02 mg/L, respectively. This indicates local contamination of the Novosibirsk reservoir littoral with decomposition products. The aquatic management, water level regulation, and control of undesirable species should take into account the likelihood of water quality decreasing as a result of macroinvertebrate mass mortality.

Aliens and Returnees: Review of Neobiotic Species of Freshwater Mollusks in Siberia from the Kazakhstan Steppe to the Arctic Tundra

“…Since then, the volume of new information about aquatic mollusk species new to Siberia has grown significantly. In addition to the registration of new species in the malacofauna of Siberia and new localities of previously known species [11][12][13][14][15][16][17], there have been works devoted to the ecology of recent migrants in Siberian reservoirs [5,[18][19][20][21], as well as publications interpreting the problem from a broader point of view, in particular, raising the question of whether all newly registered species must be considered as "real" aliens, or whether one should rather speak about restoring a part of the original range once lost by some of these species, not about introductions and/or invasions in the commonly accepted sense of these terms [16,22].…”