Lipid components and utilization in consumers of a seagrass community: An indication of carbon source

1. 1. The lipid components of three animals, the rock crab Nectocarcinus integrifons , the rock flathead Platycephalus laevigatus and the southern garfish Hyporhamphus melanochir , feeding in the seagrass beds at Corner Inlet, Victoria, Australia have been examined in detail in order to provide further information on seagrass community structure. 2. 2. Biological marker compounds detected within animal gut content material were used to recognize dietary sources and then utilized by community members. 3. 3. Both H. melanochir and N. integrifons have been shown to ingest and to varying degrees incorporate seagrass lipid material, thus further confirming the importance of seagrass carbon in the Corner Inlet environment. 4. 4. The southern sea garfish H. melanochir is observed to remove C 18 PUFAs (polyunsaturated fatty acids) from ingested seagrass material. 5. 5. Seagrass sterols are altered during incorporation into the lipids of this fish. 6. 6. Lipid-rich digestive juices play a role in the digestive processes of all three animals. 7. 7. Components tentatively identified as (NMI) (non-methylene interrupted) fatty acids have been detected in the lipids of the garfish H. melanochir and the crab N. integrifons . 8. 8. The fecal material of all three animals represent possible sources of these lipids (NMI acids) in Corner Inlet sediments. 9. 9. Based on lipid compositional data, N. integrifons feeds on Posidonia australis detritus and associated epiphyte material. 10. 10. The removal of both plant and epibiota cellular lipids along the digestive tract of the crab was observed, although structural components such as long chain mono- and α,ω-dicarboxylic acids, which have been previously recognized as seagrass marker lipids are not directly absorbed.