Marine and Freshwater Research Marine and Freshwater Research Society
Advances in the aquatic sciences

13C/12C ratios in marine food webs of the Torres Strait, Queensland

B Fry, RS Scalan and PL Parker

Australian Journal of Marine and Freshwater Research 34(5) 707 - 715
Published: 1983


During a research cruise in 1979 to the area between New Guinea and northern Australia, 250 samples were collected for measurement of 13C/12C (δ13C) to analyse carbon flow in tropical marine food webs. Plants at the base of food webs could be divided into two groups on the basis of their mean δ13C values: benthic seagrasses (-8.8‰), macroalgae (-12.5‰) and epiphytic algae (-13.3‰) were enriched in 13C (had less-negative δ13C values) when compared to planktonic samples (-21.8‰). Animals collected offshore were enriched in 13C by up to 9.1‰ relative to planktonic samples and seemed to show an increasing 13C enrichment with increasing trophic level. Relative to these offshore specimens, animals collected in intertidal seagrass meadows were usually enriched in 13C by 2-8‰, indicating that 13C-enriched benthic plants are important food sources in grassflats. Unusual 13C- enriched values of -3 to -7‰ among benthic chitons, gastropods and holothurians at one grassbed site suggest that unsampled benthic microalgae are also important sources of food-web carbon in the Torres Strait.

© CSIRO 1983

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