Salinisation effects on freshwater macrophyte growth and establishment in coastal eutrophic agricultural ditches

The presence of submerged macrophytes is a desired environmental target for coastal freshwater ecosystems. Maintaining rich community these species can be challenging as salinisation by sea-level rise poses an increasing threat to ecosystem integrity. We tested the effect on growth and germination experimentally using field sediment. In 56-day experiment, macrophyte was exposed salinity treatments representing seasonal water management scenarios (a decreasing from 1,500 300 mg NaCl/L, stable NaCl/L NaCl/L), crossed with simulating periodic turbidity pulses. All except Elodea nuttallii grew poorly saline eutrophic sediment, reflecting challenges in systems. Surprisingly, highest biomass achieved scenario NaCl/L. second field-collected sediments were incubated at (representing summer winter scenarios), capacity existing seedbank quantified. Most germinated seedlings did not reach maturity irrespective treatment. This indicated that sediment salinity, rather than column determined seedling establishment success. Interestingly, established characteristic habitats, thus indicating maladaptation seedbank. Our results show mismatch between high level overlaying may hamper growth. Furthermore, freshwaters should evaluated carefully. nuttalli, which has wide tolerance range nutrients outperformed other our study. Thus, similar traits most successful establishing stands eutropic wetlands.