Accelerated erosion of saltmarshes infested by the non-native burrowing crustaceanSphaeroma quoianum

摘要

Lateral erosion of saltmarshes is affected by many abiotic and biotic factors. While abiotic factors are typically regarded as primary drivers of erosion, biotic influences such as burrowing or bioturbating taxa can also extensively modify the physical structure of this marine habitat. Many estuaries on the Pacific coast of North America have been invaded by populations of the burrowing non-native isopod Sphaeroma quoianum, which are thought to exacerbate the erosion of saltmarshes. We conducted a mensurative experiment to examine the relationship between populations of S. quoianum and lateral erosion rate of saltmarshes in Coos Bay, Oregon, USA. After 1 yr, we measured higher lateral erosion rates, more undercutting, and higher numbers of calved and slumped marsh sections in marsh sites infested by S. quoianum than in uninfested sites. This effect was also consistent at smaller spatial scales: we found lateral erosion was 300% higher in burrowed areas than in adjacent (within approx. 1 m) unburrowed areas within infested sites. Our results suggest that the prodigious burrowing by dense populations of S. quoianum can accelerate erosion rates in saltmarshes and are substantial geomorphic agents of change in estuaries on the Pacific coast of North America.