caa a22 4500 445894687 CHVBK 20180317145627.0 cr unu---uuuuu 170323e20110401xx s 000 0 eng 10.1007/s10750-010-0593-0 doi (NATIONALLICENCE)springer-10.1007/s10750-010-0593-0 Influence of substratum on the variability of benthic biofilm stable isotope signatures: implications for energy flow to a primary consumer [Elektronische Daten] [Sally Hladyz, Robert Cook, Rochelle Petrie, Daryl Nielsen] Benthic biofilms have been identified using stable isotope analysis (SIA) as an important resource supporting many freshwater food webs. However, biofilm δ13C signatures are highly variable in freshwaters, which may hamper our understanding of energy flow through food webs in these systems. There has been little consideration of the influence that substratum may have on biofilm δ13C signature variability and energy flows to primary consumers. We investigated the effect of organic and inorganic substrata on biofilm dynamics by examining: (1) temporal variability of biofilm stable isotope (δ13C, δ15N) signatures on allochthonous leaf-litter (Eucalyptus camaldulensis) and cobble substrata over 12months in a lowland river in south-eastern Australia; and (2) the effect of substrata on biofilm energy flows to a grazer snail, Physa acuta (Gastropoda: Physidae), using SIA and ecological stoichiometry in a laboratory experiment. The temporal study indicated that cobble biofilm varied significantly in δ13C signature during the 12months (up to 11‰), whereas the δ13C signature of leaf biofilm was less variable (less than 2‰). In contrast, biofilm δ15N signatures varied temporally on both cobble (2.6‰) and leaf (1‰) substrata. This suggests that leaf biofilm was more reliant on leaf tissue for carbon and therefore less limited by carbon supply than cobble biofilm whereas for nitrogen biofilm on both substrata was reliant on external sources. In the laboratory experiment, snails fed leaf biofilm reflected more of an allochthonous δ13C signature than cobble biofilm fed snails, suggesting assimilation of leaf carbon via the heterotrophic microbial community within the biofilm. Snails grew largest on cobble biofilm, which had lower C:N ratios than leaf biofilm. Our results demonstrate that the type of substratum can influence the temporal variability of biofilm δ13C signatures and energy flow to primary consumers. Springer Science+Business Media B.V., 2011 Allochthonous nationallicence Autochthonous nationallicence Trophic pathways nationallicence Temporal dynamics nationallicence Periphyton nationallicence Physa acuta nationallicence Hladyz Sally eWater Cooperative Research Centre, Canberra, Australia aut Cook Robert La Trobe University, PO Box 821, 3689, Wodonga, VIC, Australia aut Petrie Rochelle La Trobe University, PO Box 821, 3689, Wodonga, VIC, Australia aut Nielsen Daryl eWater Cooperative Research Centre, Canberra, Australia aut Hydrobiologia Springer Netherlands 664/1(2011-04-01), 135-146 0018-8158 664:1<135 2011 664 10750 https://doi.org/10.1007/s10750-010-0593-0 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s10750-010-0593-0 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Hladyz Sally eWater Cooperative Research Centre, Canberra, Australia aut NATIONALLICENCE 700 1- Cook Robert La Trobe University, PO Box 821, 3689, Wodonga, VIC, Australia aut NATIONALLICENCE 700 1- Petrie Rochelle La Trobe University, PO Box 821, 3689, Wodonga, VIC, Australia aut NATIONALLICENCE 700 1- Nielsen Daryl eWater Cooperative Research Centre, Canberra, Australia aut NATIONALLICENCE 773 0- Hydrobiologia Springer Netherlands 664/1(2011-04-01), 135-146 0018-8158 664:1<135 2011 664 10750 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer