FIRST RESULTS KATRINE CHALUT1, PIERRICK BARBIER1, PHILIPPE ARCHAMBAULT1, CHRISTIAN NOZAIS2
Benthic fauna plays a key role in the recycling of organic matter at the seafloor as it can both help organic matter decomposition and channelling to higher trophic levels. It has been suggested that the shift in primary producers inferred by global warming will impact on both the quantity and the quality of food exported towards the seabed. This may lead to possible changes on the structure and function of benthic ecosystems since polar benthic heterotrophs (meio- and macrofauna) depend on allochtonous organic material for their energetic requirements.
Empirical fractionation factor of 3.4 %o for 15N and 1 %o for 13C is used
O. sericeum preferentially consumes cumaceans and organic matter from sediment
1 Université du Québec à Rimouski (ISMER), Rimouski, Canada 2 Département de biologie, Université du Québec à Rimouski
LEGEND
So far, we obtained results for 3 stations
Sediment SPOM Copepods Cumaceans
Ophiocten sericeum
Canadian Archipelago
STATION 108
2008 2009 0% 20% 40% 60% 80% 100%
Contribution to diet (%)
STATION 109
Foraminiferans seem to be an important part of macrofaunal organisms’ diet Ophiura sarsi Nothria conchylega
Determine the origin and sources of organic matter assimilated by Arctic macro and meiofaunal organisms, along the West-East gradient in Canada, using stable isoptopes
3- Freezedrying of all the samples
2- Faunal identification
We would like to thank the CCGS Amundsen Crew, Chief Scientists, Mélanie Lévesque, Heike Link, Laure de Montety, Mathieu Babin and Cécile Renault. We are grateful for the financial support from the NSERC Canadian Healthy Oceans Network.
Foraminiferans
Astarte montaigu 0% 20% 40% 60% 80% 100%
Contribution to diet (%)
High 15N values for nematodes suggest that it feeds on macrofaunal carcasses
STATION 303
Psolus phantapus Ophiocten sericeum
6- Weighing and encapsulation 4- Grinding 7- Analysis with COSTECH ECS 4010 coupled with DeltaPlus XP Isotope 5- Decarbonation of Ratio Mass Spectrometer Echinoderms and (IRMS) sediment (in part)
1- Samples of sediment and fauna collected during 2008 and 2009 Amundsen expeditions in the Canadian Arctic
Sediment
Strongylocentrotus
Sediment
Ophiura robusta
Copepods
Ophiopus arcticus
Nematodes
Onuphidae pieces
Others
8- Data analysis with SIARpackage
0% 20% 40% 60% 80% 100%
Contribution to diet (%)
CONCLUSION First results suggest that meiofauna mediates flow of organic matter between muddy deposits and higher trophic levels. Furthermore, our isotopic results demonstrate that sediment is a coarse descriptor when it comes to study macrofaunal diet. Next steps in this study will be first to analyse the rest of the stations then study specifically meiofauna diet, estimate trophic levels and finally compare isotopic values between the stations.
