Rocky Reefs Provide Foraging Habitat For Dugongs In The Darwin Region Of Northern Australia

Abstract

DUGONGS (Dugong dugon) are large mammalian herbivores found in tropical and sub-tropical waters from the east coast of Africa to Vanuatu in the western Pacific Ocean (Rice 1998). Foraging studies throughout their range indicate that their diet is dominated by seagrass (Marsh et al. 1982; Preen 1995; Preen and Marsh 1995; Anderson 1998; Das and Dey 1999). Aerial surveys (Marsh and Saalfeld, 1989; Preen et al. 1997), land-based and boat-based observations (Anderson 1982 1994; Aragones 1994) and satellite tracking data (Marsh and Rathbun 1990) indicate that dugong distribution is closely associated with seagrass beds. Algae is known to occur in food samples from dugongs (Heinsohn and Birch 1972; Marsh et al. 1982; Erftemeijer 1994; Preen 1995) but its presence in the diet has been described as incidental (Marsh et al. 1982) or linked to large-scale losses of seagrass (Spain and Heinsohn 1973; Marsh et al. 1982; Preen and Marsh 1995). This note contains opportunistic observations of long-term feeding by D. dugon on algal covered rocky reefs in the Darwin region of the Northern Territory.