Historical loss and current rehabilitation of shoreline habitat along an urban-industrial River-Detroit River, Michigan, USA

Abstract

The purpose of this study was to evaluate the historical loss and current shoreline habitat rehabilitation efforts along the urban-industrial Detroit River using geographical information system methods and a shoreline survey. This study found a 97% loss of historical coastal wetlands to human development. By 1985, 55% of the U.S. mainland shoreline had been hardened with steel sheet piling or concrete breakwater that provide limited habitat. Since 1995, 19 projects were implemented, improving 4.93 km of shoreline habitat. A comparison of the 1985 and 2015 georeferenced aerial imagery showed that 2.32 km of soft shoreline was also converted to hard shoreline during this timeframe. Of the 19 projects surveyed, 11 representing 3.35 km made habitat improvements to shoreline that was already georeferenced as "soft", three representing 360 m converted shoreline from "hard" to "soft", and five representing 1.22 km added incidental habitat to hardened shoreline. Even with the addition of 1.58 km of new soft shoreline and incidental habitat, there was an overall net loss of 0.74 km of soft shoreline over the 30-year timeframe. To reach the "good" state of at least 70% soft shoreline, an additional 12.1 km of soft shoreline will have to be added. This confirms that shoreline hardening continues despite the best efforts of resource managers and conservation organizations. Resource managers must become opportunistic and get involved up front in urban waterfront redevelopment projects to advocate for habitat. Incremental progress will undoubtedly be slow following adaptive management.