The Role of Burrows of the SW Atlantic Intertidal Crab Chasmagnathus granulata in Trapping Debris

Abstract

The burrowing crab Chasmagnathus granulata is the most abundant macroinvertebrate on intertidal mudflats and salt marshes of the South Western Atlantic. This species excavates and maintains large semi permanent open burrows with a mouth opening that may reach 20 cm in diameter and a volume of up to 2 l. Areas populated by crabs retain a significantly larger amount of debris (mainly plastics) on the surface and have larger amounts of buried debris in the sediment than areas without crabs. Field experiments showed that due to their hydrodynamic characteristics, burrows in the mudflats work as passive traps for debris enhancing their retention. Given the extensive intertidal area inhabited by this species in SW Atlantic estuaries, crab bed areas should be considered as large areas that retain debris burying it in the soft bottom environment.