The construction of sea walls (also referred to as coastal armoring or shoreline hardening) in or immediately adjacent to sea turtle nesting habitat can degrade nesting habitat, deter sea turtles from nesting, and increase beach erosion. As erosion from storms, sea level rise and poorly located development continues to threaten beaches and upland structures, landowners often resort to sea walls to protect their property. Coastal Tech, under a pro bono contract with Sea Turtle Conservancy, produced a report to inform the public and provide guidance on how to best construct and locate seawalls as far landward as practicable and in accordance with state laws. The report, titled, “Guide to Siting of Seawalls” can be read on STC’s website here. Coastal Tech is a consulting firm specializing in coastal engineering and coastal zone management and can be found on the web at http://www.coastaltechcorp.com
Sea walls literally draw a line in the sand and prevent beaches from migrating or from recovering naturally after storm events. They lock up sand on the landward side that would normally be deposited onto an eroded beach. When they interact with waves, they deflect the wave energy back onto the beach in front of or to the sides of the wall, resulting in increased erosion and a lowering of the beach, especially immediately in front of the wall.
Because sea walls can have such significant harmful impacts to the beach and dune system and to sea turtle nesting habitat, they are generally discouraged and alternatives such as dune restoration and beach renourishment are preferred to provide protection for upland structures. Of course, not building too close to the beach is the best way to avoid needing a sea wall. Too often however, we allow people to build far too seaward and on top of the most seaward dunes.
By blocking access to the upper portion of the beach, sea walls cause sea turtles that are trying to nest to turn around and head back to the surf, abandoning their nesting attempt (referred to as a false crawl). They also cause turtles to nest in less than optimum or suitable habitat. They can nest right in front of the wall where the nest and hatchings are susceptible to waves and repeat inundation from the surf. In this photo sea turtles trying to access the safe upper portion of the beach were forced to nest at the base of the sea wall. The stakes mark the turtle nests.