Author(s): Weiwei Zhou; Dongdong Shao
Linked Author(s): Dongdong Shao
Keywords: No Keywords
Abstract: In recent years, ecosystem-based flood defence, i. e., eco-shoreline or living shoreline, that is more sustainable and cost-effective than conventional coastal engineering structures has been brought into large-scale practice. Numerous laboratory experiments have been performed to explore the wave-attenuation effects of saltmarsh plants that are widely used in eco-shoreline, and yet no study has ever been conducted on the physiological and biochemical responses of saltmarsh plants to long -term wave exposure, presumably due to the constraint that traditional wave generator fails to provide long-term stable wave conditions necessary for physiological experiments. In this study, a long-term shallow water wave environment simulator using crank-yoke mechanism was built in the laboratory to address this gap. Experiments using the wave simulator were conducted for 8 weeks in a greenhouse. The temperature was maintained at 24–30°C. 5‰ artificial sea water was filled in the test tank, and the water was changed every week. After being acclimatized, S. alterniflora individual plants (initial height 30 cm) were planted in each of three streamlined cuboid containers (12cm×12cm×20cm), which were partially submerged in the test tank, and undertook horizontal sinusoidal motion imposed by the crank-yoke mechanism to mimic plants exposed to shallow water waves. The S. alterniflora plants and the substrate filled in the containers were collected from the Yellow River Delta. Shallow water waves with four wave heights (H: 0.055,0. 069,0. 044 and 0.056m), two water depth (0.09m and 0.22m) and two wave periods (2s and 3s) were simulated in the experiments. A no wave condition was also tested as control. Key physiological and biochemical parameters, such as stem length, peroxidase activity, catalase, superoxide dismutase, ascorbate peroxidase, etc., were measured on a weekly basis to monitor the plant response. Differences among the various groups were analyzed using repeated measures ANOVA to check for significance (P < 0.05). The results can help inform eco -shoreline projects in terms of plant selection and transplantation timing optimization, etc.