The use of trawl, grab and camera in estimating marine benthos

Abstract

Certain animals of the epifauna, because of their distribution over the bottom, are often difficult to sample quantitatively. They may occur as individuals widely dispersed over a large area, or they may be present in dense aggregations which themselves have a patchy distribution. In the past, workers have tried to estimate the numbers of such animals by the combined use of trawls and grabs of various types. The post-war development of underwater photography suggests that the camera will be a useful additional tool (e.g. Vevers, 1951, 1952). During the testing of an underwater camera from Aberdeen an opportunity was taken to compare the estimates of some of the larger epifauna from grab and trawl hauls with estimates derived from underwater photographs. The results are described in this paper.