Landscape-Level Impacts of Shoreline Development on Chesapeake Bay Benthos and Their Predators
Within the coastal zone, waterfront development has caused severe loss of shallow-water habitats such as salt marshes and seagrass beds. Little is known about the impact of habitat degradation and ecological value of subtidal shallow-water habitats, despite their prevalence. In coastal habitats, bivalves are dominant benthic organisms that can comprise over 50% of benthic prey biomass and are indicative of benthic production. We examined the effects of shoreline alteration in shallow habitats by contrasting the benthos of the subtidal areas adjacent to natural marsh, riprap, and bulkhead shorelines in three Chesapeake Bay subestuaries that differ in the level of shoreline development. In all cases, benthic abundance and diversity were higher in subtidal habitats near natural marsh than those near bulkhead shorelines; however, abundance and diversity were intermediate near riprap shorelines, and appeared to depend on landscape features. In heavily impacted systems such as the Elizabeth-Lafayette system, benthos adjacent to riprap was depauperate, whereas in less-developed tributaries (York River and Broad Bay), benthos near riprap was abundant and was similar to that near natural marsh shorelines. Furthermore, predator density and diversity were highest adjacent to natural marsh, intermediate near riprap, and low near bulkhead shorelines. There is thus a crucial link between natural marshes, benthic infaunal prey in subtidal habitats, and predator abundance. Restoration of living shoreline habitats is likely to have benefits for adjacent benthos and their predators. Protection and restoration of marsh habitats may be essential to the maintenance of high benthic production and consumer biomass in Chesapeake Bay. Moreover, the collective impacts of the system-wide, landscape-level features are felt from the benthos through higher trophic levels.