Effect of temperature and nutrients on the competition between free-fl oating Salvinia natans and submerged Elodea nuttallii in mesocosms

摘要

In many aquatic ecosystems, free-fl oating plants compete with submerged plants for nutrients and light. Being on top of the water surface free-fl oating plants are superior competitors for light. Submerged plants can take up nutrients from the sediment and the water column, hereby reducing these levels for free-fl oating plants. Global warming may change chances of successful species invasion and can alter species dominance. We studied the combined effects of nutrient loading and increased temperature on the competition between the potentially invasive free-fl oating Salvinia natans (L.) All. and the naturalized submerged Elodea nuttallii Planch. St. John by an outdoor mesocosm experiment under temperate climate conditions (The Netherlands) over a period of 71 days. The free-fl oating S. natans benefi ted from increased temperature and increased nutrient loading and limited the chances for the submerged E. nuttallii to take advantage of these changed conditions. S. natans substantially increased temperature in the top layer, while limiting the temperature increase below the mat. Our results suggest that with global warming, invasive free-fl oating plants might become more successful at the expense of submerged plants.