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Climate change and sea level rise have the potential to alter the vegetation composition of our aquatic ecosystems. In order to achieve resilience and stability in our ecosystems, we need a better understanding of future changes based on sound scientific projections. Using actual sea water for implementing sea level salinities in laboratory and greenhouse experiments is not always feasible, hence commercial aquarium mixes might be a good substitute to mimic natural saltwater-freshwater systems. In this study, we compared the growth of Vallisneria americana (Eel-grass) and Hydrilla verticillata (Hydrilla) under 4 salinity levels (0.5, 1.0, 2.5 and 5.0 ppt) induced by 4 different salt types (Sea Water, Instant Ocean Aquarium Mix, NaCl and Morton Sea Salt). Aquatic plants were grown in separate pots filled with Sand or Peat and were submersed in 60 L mesocosms. Salinity levels were increased gradually and water level, salinity and pH were monitored every week. After 10 weeks exposure to increased salinity levels, plants were visually evaluated on a 0-10 scale and destructively harvested to record wet and dry weights. Results showed that Peat and Sand did not substantially impact plant’s biomass. Mesocosms which were treated with Morton or NaCl had severe Hydrilla damage at 2.5 ppt and all Hydrilla were eradicated at 5 ppt. While Instant Ocean Aquarium Mix or Sea Water treated mesocosms had less Hydrilla damage at both 2.5 and 5 ppt levels and no eradication was observed. Vallisneria was not affected by different salt types in various salinity levels except at 0.5 ppt level where NaCl had smaller biomass than all other salt types. Overall, our results suggest that Instant Ocean Aquarium Mix is a strong candidate for increasing salinity levels in sea level rise experiments, as it showed a similar effect on plant’s biomass as Sea Water. |
