1. Relative contributions of biodiversity and environment to seafloor ecosystem functioning Belley, R. & Snelgrove P.V.R. (Submitted MEPS) Memorial University International Marine Conservation Congress Aug 2 nd, 2016

2. Introduction Continental margins mostly soft-sediments cover ~ 16% of oceans Among other functions, provides > 80% benthic remineralization Organic matter remineralization fuels surface water productivity

3. OM degradation process utilizes O 2 and generates flux of nutrients at the seafloor Benthic fluxes of O 2 and nutrients can be measured and used as a measure of ecosystem functioning Factors influencing benthic fluxes: – Concentration gradients and molecular diffusion – Microbial activity – Environmental variables e.g. Bottom water, organic matter and sediment characteristics – Biological variables e.g. Biomass, functional and species diversity Functional diversity: “the amount of functional space filled by the community” (Villéger et al. 2008) Introduction

4. Measure benthic fluxes of O 2 and nutrients (ammonium, nitrate, nitrite, phosphate and silicate) Evaluate the contributions of: 1) Biodiversity 2) Environment Objectives

5. ONC underwater installations Saanich Inlet (SI) Delta Dynamic Lab (DDL) Strait of Georgia Central (SoGC) Strait of Georgia East (SoGE) Study sites

6. Sediment core samples collected with ROV ROPOS – 21 cores On board incubations – In situ temp + dark – 12-24 hrs – Water homogenized – Nutrient fluxes – O 2 uptake Overview of the study

7. O 2 micro-profiles (OPD) Microbial and sediment characteristics Overview of the study

8. Sediment sieved (300 µm) Specimen identification – ~ 2000 ind. – 119 taxa Diversity – N, S, Simp, H’, J’, es25 Functional diversity – 5 traits and 24 modalities – “FD” package R and Primer Overview of the study Paraprionospio pinnata TraitsModalities Feeding typeCarnivore/predator Detritus feeder Filter/suspension feeder Funnel feeder Grazer Omnivore Parasitic Scavenger Surface deposit feeder Sub-surface deposit feeder SizeSmall (< 1 cm) Medium (1-5 cm) Large (> 5 cm)

9. Response variablesEcosystem function Nutrient fluxes (NH 4 +, NO 3 -, NO 2 -, SiO 2 & PO 4 3- ) OM remineralization O 2 uptake Variables of interest Environmental variablesDiversity indices Chl a:PhaeoFunctional richnessFunctional evenness Microbial abundanceCWM limited movementSimpson’s diversity PorosityCWM funnel feedersAbundance DepthCWM sub-surface deposit feedersCWM surface modifiers TempCWM slow movement CWM = Community-level weighted mean

10. Results: Community and flux variations Community assemblages: All significantly different Benthic fluxes: Differences less consistent SoGE ≠ DDL, SI & SoGC SI = DDL & SoGC P(perm)=0.0001

11. Results: RDA environmental variables Stepwise selection of variables best explaining flux variation (5/11) – R 2 = 0.58, Adj. R 2 = 0.44 – Chl a:Phaeo = 19% – Microbial N = 15%

12. Results: RDA diversity indices Variables best explaining flux variation (9/25, R 2 = 0.68, Adj. R 2 = 0.41) – FRic = 20% – Bioturbation = 19% – Bio-irrigation = 14%

13. Results: Variation partitioning analysis Combine 2 RDAs to explain benthic flux variation: – Environment = 21% – Diversity = 19% – Shared = 23% – Total = 63%

14. Environment and diversity play a similar role in benthic flux variation and ecosystem functioning – Large proportion is shared Most important drivers – Functional richness: Better than sp. diversity and abundance – Bioturbation = 19% – Bio-irrigation: Funnel (12 ind.) and sub-surface feeders = 14% – Food quality: Chl a:Phaeo – Microbial processes: Microbial abundance 37% of benthic flux variation not explained – Different water nutrient concentrations? Discussion

15. Conclusions Functional richness better predictor of ecosystem functioning than species diversity and abundance Funnel feeders identified as geochemical keystone species Biodiversity and environment play a similar role in controlling OM remineralization Implications: Need to maintain functional richness to maintain ecosystem processes, functions and services Species loss associated with environmental changes could reduce benthic-pelagic coupling essential for ocean productivity Conclusions and implications

16. Thanks to Drs. Philippe Archambault, Kim Juniper, Verena Tunnicliffe, Suzanne Dufour, Chih-Lin Wei, Ryan Stanley, the Snelgrove lab team, Heike Link, Adeline Piot, Lina Stolze, Carol Anstey, Richard Rivkin, Ocean Networks Canada and Schmidt Ocean Institute. Thanks to the officers and crew of the CCGS John P. Tully, R/V Thomas G. Thompson and R/V Falkor and to the CSSF ROPOS team. Acknowledgments Twitter: @ BelleyRenald Thank you Wormly!