| Popis: |
Potential food sources and dominant invertebrates and fishes were collected for the examination of variability in 13 C/ 12 C and 15 N/ 14 N to determine the sources of carbon available to consumers within a Western Australian Posidonia sinuosa -dominated seagrass bed. Autotrophs showed a wide distribution of δ 13 C values, with P. sinuosa at −11.3 ± 0.8‰ and macroalgae ranging from −16.6 to −31.7‰. This variation allowed us to successfully identify macroalgae as the main contributor of carbon to the trophic structure, although no distinction could be made between epiphytic macroalgae on seagrass, or allochthonous macroalgal sources. The range in δ 15 N ratios among potential food items at the trophic base was too small to make it useful as tracer of nitrogen flow pathways, but it consistently increased from macrophytes and detritus (4.1–6.8‰), to invertebrates (5.7–7.4‰) located near the middle of the food web, to fishes (8.3–11.9‰), with piscivorous species such as Leviprora inops generally having a higher 15 N. δ 13 C of seston (−12.8‰) and sedimentary organic matter (−8.7‰) indicate that seagrass material is the main contributor to these two carbon pools, and that very little of it contributes to animal biomass. |
Full Text from ScienceDirect