ANALYZING FUTURE COMPETITION BETWEEN NATIVE AND NONNATIVE SNAIL SPECIES IN THE LOWER EBRO RIVER (NE SPAIN)

ISABEL MUÑOZ; MIQUEL ANGEL LÓPEZ-ROBLES; LOPEZ VAN OOSTEROM MARIA VANESA; ALEIX NÚÑEZ; JOAN PERE CASAS-RUIZ

Olomouc

Simposio; 10th European Symposium for Freshwater Sciences (SEFS10); 2017

Rivers are ecosystems especially vulnerable to biological invasions. Modifications of aquatic habitats, flow regulation and water abstraction affect native species and create the conditions suitable for tolerant non-native species. In 2010, the apple snail (Pomacea maculata) invaded rice fields in the Ebro River Delta causing devastating effects due to its diet flexibility and high reproductive rate. Currently, the snail is also present in some wetlands, and it has been found moving upwards along the Ebro riverbed. The native endemic species Melanopsis tricarinata lives in the same area, and will have to compete with the apple snail in the next future.The present study aims to experimentally analyze, the response of both species to changes in temperature and dryness, factors that will increase in future scenarios of climate change. In addition, we study their diet in natural conditions to determine potential food competition.The lower part of the Ebro is highly regulated. Flow changes determine differences in water level, periodic dry/wet conditions where the non-native species could have advantages. In this sense, we have also modeled the surface of riverbed emerged according to different flow management conditions. Results show that P. maculata supports better dry conditions and higher temperatures regarding to M. tricarinata. Stable isotopic analyses determine that diet of both species is similar with high niche trophic overlapping. Flow reduction increases the habitat that favors non-native species. We found high risk of competition and greater survival for the non-native species that would favor its spread.