CONTRASTS BETWEEN ARCTIC AND ANTARCTIC FJORD SEAFLOOR ECOSYSTEMS AND

FOODBANCS2 POTENTIAL RESPONSE TO CLIMATE CHANGE AA Craig R. Smith1, Laura Grange1,4, David J. DeMaster,2 Michael J.Derocher1, David Honig3 1 2 3 4 Dept of Oceanography, University of Hawaii at ManoaManoa;; North Carolina State University; Duke University; National Oceanography Center, UK G Introduction Results Subpolar fjords with tidewater glaciers are warming rapidly in both the subpolar • Megabenthic abundance is 3-36 times higher in WAP fjords than on open shelf (p <<0.05) Arctic and the West Antarctic Peninsula (WAP). and does not decline within 5 km of tidal glaciers(Figure 6A). Arctic-fjord studies on Baffin Island, Svalbard, and Greenland indicate intense glacial • Species richness is higher in WAP fjords compared to the open shelf (p<<0.05) and remains sedimentation disturbance in inner-middle Arctic fjords, yielding steep declines in high near glaciers (Figure 6B). benthic species diversity and trophic complexity from the open shelf to inner fjord •Fjords add substantially (>60 spp.) to the regional species richness at 400-650 m depths basins (Fig. 1 & 2). (Fig. 7). Megabenthic abundance Figure 2. Decrease in species richness from open shelf into three Figure 6. (A) inner subpolar fjords in Megafaunal Svalbard (Wlodarska- abundance and Kowalczuk et al. 2012). (B) species richness in WAP fjord and shelf stations versus Species richness per 90 m2 transect distance to B nearest tidal glacier (Grange & S mith 2013). Figure 7. Estimated total species richness on the open shelf (85 spp.), in the Figure 1. Arctic subpolar fjords exhibit intense up-fjord three fjords combined (100 spp.), and in shelf and fjord systems combined (140 disturbance gradients with proximity to tidal glacier spp.) using the Chao 1 species richness estimator (Grange & Smith 2013). sedimentation and turbidity (Wlodarska-Kowalczuk et al. 2005). Primary Producer Sources based on -13C and -15N Analyses Climate warming is predicted to reduce sedi- Shelf Stations Andvord Bay mentation in Arctic fjords, enhancing benthic community abundance and biodiversity (Fig. 3). CS

Figure 3. Baffin Island subpolar fjord model of benthic community succession with glacial Do these Arctic models apply to the retreat; sedimentation disturbance decreases, WAP fjords? & diversity and abundance increase, with climate warming (Syvitsky et al. 1989). If so, we predict that, compared to the open shelf, WAP fjord benthos will have: • Low abundance Figure 9. Contributions of phytoplankton, ice algae, and macroalgae to Figure 8. Functional groups in fjords and on shelf. m/df = biomass of benthic megafauna on shelf and in fjord (Andvord). Con- • Low species richness mobile deposit feeders, s/df = sessile dep. feeders, m/sf = tributions inferred from -13C and -15N using Bayesian mixing model mob. suspension feeders, s/sf = sess. susp. feeders, m/c = with uninformative priors. Each point = most probable estimate for one • Low trophic comppylexity mob. carnivores, m/so = mob. scavengers-omnivores. species. SDF = surface dep. feeder, SSDF – subsurface dep. feeder. And climate warming will increase fjord benthic biomass/diversity/trophic complexity. •WAP fjord trophically are complex, with few mobile deposit feeders in inner basins (Fig. 8). • Sources of primary production to benthic food webs appear more varied in WAP fjords than Materials and Methods on the shelf, with greater inputs from ice algae and macroalgae (Fig. 9).

Andvord Bay Arctic – Prince William We conducted yoyo-camera surveys (Fig. 4) Sound of soft-sediment megafauna at 500–600m depths in three WAP subpolar fjords and compppared results to three open shelf stations Conclusions at similar depths (Fig. 5). WAP Fjord megabenthic communities are hotspots of biodiversity and benthic Down-fjord community structure at distances abundance, in dramatic contrast to predictions from models of Arctic subpolar fjords. of 2-20 km from tidal glaciers was compared to that on the open shelf >100 km from the Why such differences in the glaciomarine benthos in Arctic vs Antarctic fjords? nearest glacier. •WAP fjords area at an earlier stage of warming with less melting/terrigenous sediment input B A yielding little burial/turbidity disturbance of water column and benthos. Figure 5. Study sites in inner, middle and outer basins of the fjords Andvord, Flandres and Barilari Bay, and •Most sediments/fresh water enter WAP fjords in icebergs and advect out to sea, causing the three open shelf stations (B, E and F) (Grange and little se dimen ta tion an d a llow ing hig h p hy top lan kton, ice-alllgal an d macroalllgal prodtiduction. Smith, 2013). In addition, Blake trawl samples were used to collect We speculate that climate warming will increase glacial melting/terrigenous sediment- megafauna for -13C and -15N analyses to evaluate ation in WAP fjords, potentially “snuffing out” these fjord biodiversity hotspots. Figure 4. (A) Yoyo camera and food-web structure using Hierarchical Bayesian Stable Acknowledgements: We thank the captain/crew of the Nathaniel B Palmer and our LARISSA and FOODBANCS2 (B) seafloor image from Andvord Bay. Isotope Mixing Models (Semmens et al. 2009). collaborators. Funding was provided by the National Science Foundation, Office of Polar Programs. Literature cited: Grange & Smith 2013, PLoS ONE 8(11): e77917. doi:10.1371/journal.pone.0077917. Semmens et al. 2009. PLoS ONE 4(7): e6187. doi:10.1371/journal.pone.0006187. Syvitski J.P.M. et al. 1989, Arctic 42(3): 232-247. Wlodarska-Kowalczuk et al. 2005, Mari Ecol Prog Ser 303: 31-41. Wlodarska-Kowalczuk et al. 2012, Mar Ecol Prog Ser 463: 73–87.