Diet selection by immature green turtles, Chelonia mydas, in subtropical Moreton Bay, south-east Queensland

Abstract

Diet selection by immature green turtles (Chelonia mydas) in Flathead Gutter, Moreton Bay, was determined by examining food ingested in relation to food availability (measured as vegetation composition and abundance within the feeding site). Food composition was sampled by oesophageal lavage. Turtles were repeatedly located over a 10-week period by means of sonic telemetry and visual identification. The number of resightings indicated that these turtles remained within their feeding grounds for at least short periods of time. Immature green turtles fed on both seagrass and algal species. However, most fed selectively on algae, primarily Gracilaria sp. Food items consumed frequently by these turtles were analysed for total nitrogen, gross energy and neutral detergent fibre levels. There was a negative correlation between fibre level and the preferred food species, where the more frequently selected species had lower levels of fibre. The preferred species also had higher nitrogen levels