The Role of Erosion by Fish in Shaping Topography Around Hudson Submarine Canyon

Abstract

ABSTRACT An 800-km2 area of rough topography around the head of Hudson Canyon off the eastern United States is attributed to erosion by tilefish (Lopholatilus chamaeleonticeps) and associated species of crustaceans. The rough topography has a relief of 1-10 m, occurs in water depths of 120-500 m, and has been cut into a semilithified, silty clay substrate since the onset of the Holocene transgression. Commercial fishing activity indicates that a large population of tilefish, which dig burrows in the sea floor, occupy the area of the rough topography. Average tilefish burrows are 1.6 m in diameter and 1.7 m in depth. They have a clustered, not uniform, distribution, and their average density is 2,500 per km2. The close match of areas of rough topography and high til fish populations, the active burrowing of the sea floor, and the clustered distribution of the burrows suggest that the hummocky topography in this area may be the result of continuous erosion by tilefish and associated crustaceans during the Holocene. An erosion rate of 13 cm per 1,000 years is necessary to create this topography during the past 13,000 years--and 18 cm per 1,000 years if(as is more likely based on the depths at which tilefish presently are found) the erosion started 9,000 years ago.