Aerial survey of a salt marsh: Ice rafting to the lower intertidal zone

Abstract

An aerial photographic survey was conducted using an ultralight aircraft to assess both the extent and the directionality of ice rafted salt marsh pear in a northern New England salt marsh. To address the extent of ice rafting, a map was constructed from aerial photographs to determine the number, area and percentage of the tidal flat covered by accumulated ice rafted peat islands. Seven percent of the tidal flat or 117·4 m 2 of the salt marsh embayment was covered by 202 transported peat islands. To address the direction of ice rafting, an ice tagging experiment tested the hypothesis that salt marsh peat is transported from the high to the low intertidal. Eighty-eight percent of the recovered ice rafted peat islands were transported to lower intertidal elevations. Thus, the ice rafting process is an important physical disturbance in this north temperate salt marsh and has the potential to impact the salt marsh peat community.