Conservation Training

Strategies for Establishing Submersed Aquatic Vegetation in Freshwater Environments Post-Dredging

July 10, 2023

11:00 am – 12:00 pm
Location: Webinar

The remediation of contaminated sediments in freshwater systems can have a significant impact on the ecology of those systems by altering or removing vegetation through dredging. Expediently returning these systems to their natural state is a high priority for all project stakeholders and can have a significant impact on project budgets and schedules. A limited number of projects have successfully addressed this issue, and the academic research in this area has not produced a conclusive list of best-practice recommendations.

The project team worked with multiple partners to develop a process for harvesting, propagating, installing, and monitoring submersed aquatic vegetation (SAV) transplants on a large scale that has produced varied and interesting results. Re-vegetation efforts began with an analysis of the physical conditions in various parts of the river to determine the locations most suitable for vegetation re-establishment. Species for re-planting were selected from those noted in pre-dredging botanical surveys and available commercially. A variety of transplanting methods and forms were tested on a small scale prior to final implementation.

The team is currently in the third year of implementation and monitoring, and preliminary results have documented total SAV cover in transplanted areas ranging from < 10% in year one to >90% by the beginning of year 3. This presentation reviews a number of variables and challenges that were encountered in the field and documents the impact these issues can have on SAV transplanting success. Some of the field conditions included in the presentation include water depth considerations, turbidity, herbivory, stock harvesting methods, harvest timing, and plant life-cycle timing. The team's hope is that this work will serve to further develop a set of best practices for ecological restoration professionals in this important, but often overlooked, aspect of sediment remediation and habitat restoration.