Students Research Presentations: Modeling estuarine living shoreline evolution with sea level rise to promote habitat for oceanic fish

Year:

2022

Source:

Ocean Sciences Meeting, Virtual

Abstract:

Many oceanic fish depend on estuarine marshes for spawning. Therefore, modeling the effects of Sea Level Rise (SLR) on marsh evolution is important. Living shorelines are native marsh plantings that increase coastal resilience to SLR and are increasingly being used in the Chesapeake Bay. Living shorelines require breakwaters to dissipate wave energy to prevent marsh erosion and facilitate sedimentation. Currently, riprap breakwaters protect living shorelines, but they cannot adapt to SLR. Alternatively, oyster castles are modular breakwater blocks that induce oyster reef development which adapt to SLR. This research used Delft3D to model the effects of SLR on living shorelines with 3 domains: 1) living shoreline, 2) living shoreline with riprap, and 3) living shoreline with oyster castles. The objectives included comparing marsh deposition between the domains and determining the important parameters affecting living shoreline geomorphology. Domains were 2km wide by 2km long and set for a temporal scale of 150 days with a morphological factor of 150 to project for 60 years. Parameters included vegetation density, nearshore slope, SLR, and suspended sediment concentration (SSC). Oyster castles facilitated greater marsh deposition than riprap at +8.9mm under current sea level, +3.5mm with SLR of 0.4m, and +3.3mm with SLR of 0.8m. Higher nearshore slope and higher SSC both increased sediment deposition in the marsh. Increased sea level and higher marsh density decreased maximum bed shear stress. Coastal resiliency projects should strive to integrate oyster castles with living shorelines to improve estuarine habitat development for oceanic fish spawning, improved water quality, and resilient shorelines. Future research should field sample riprap and oyster castle breakwaters to quantify differences in species biodiversity and abundance.

Mentors:

William Nardin, Ph.D.

Students:

Jonathan Leathers, University of Maryland College Park