1. Bottom-up drivers of species interactions on the Oregon Coast Jonathan Robinson and Bruce Menge Oregon State University – PISCO WSN 2014 Talk

2. The ocean is changing Ruggiero et al. 2010 Increasing wave height Increases in upwelling along the Oregon coast Huyer et al. 2010 Feely et al. 2009 Increasing ocean acidification What are the likely consequences for coastal ecosystems?

3. Long-Term Research in Environmental Biology (LTREB) Project Question: How will intertidal community dynamics and structure change with changing climate? (Very General) Predictions Changes could: – Alter ecological subsidies – Alter species interactions – Affect diversity, zonation, abundance – BUT – Directions of change difficult to predict mussels could decrease  increased macrophytes sea stars or whelks could decrease  increased abundance of prey  altered zonation

4. Cape Foulweather Narrower shelf Offshore currents Less retentive Cape Perpetua Wider shelf Mixed currents More retentive Cape Blanco Narrow shelf Offshore currents Stronger upwelling Less retentive Today’s focus: Central interaction in most temperate rocky intertidal communities Predator – Barnacle – Mussel interaction web Photo by E. Sanford Oregon coastal intertidal meta-ecosystem

5. Oregon capes oceanographic differences generate differences in ecological subsidies phytoplankton barnacle recruitment mussel recruitment a b b a a a b bb

6. Research Questions Effect of predation? Effects of spatial interactions (competition, facilitation)? How do interactions vary with oceanography? Hypotheses, all varying with oceanographic conditions: H 1 : Predation is strong H 2 : Mussels outcompete barnacles H 3 : Barnacles facilitate mussel colonization

7. Methods 5 Treatments +P+B+M -mesh Cape Foulweather Cape Perpetua Cape Blanco CA Oregon WA +P+B+M +mesh -P+B+M +mesh -P+B-M +mesh -P-B+M +mesh

8. Methods Cape Foulweather Cape Perpetua Cape Blanco CA Oregon WA 5 Replicates Cleared in spring Photographed once/twice a month Percent cover of species analyzed ~1500 pictures analyzed Results from 2011 & 2012 RMANOVA – Linear Constraints (post hoc)

9. p=0.02 Yes: except for CF 2011, p = 0.02 or more CP different from CF, CB; consistent with difference in larval retention, food 2012 H 1 : Predation effect? Varies with oceanography? +Pred -Pred +Pred -Pred CFCPCB All capes: Prey cover in –P > +P p=0.0005 p=<0.0001 p=0.004 p=<0.0001 2011

10. H 2 : Competition effect? Yes but context-dependent 2011 CFCPCB 2012 -P+B+M -P+B-M -P+B+M ns p=0.002ns p=0.1 ns CP: If mussels removed during colonization, barnacles persist CF, CB: Mussel removal had no effect on barnacles

11. H 3 : Facilitation effect? 2011 CFCPCB 2012 -P+B+M -P-B+M -P+B+M No. ns p=0.07 ns p=0.053ns CP: Trend towards lower abundance of mussels without barnacles, but NS CF, CB: No difference

12. Discussion Predation important everywhere Competition only occurred at CP sites Facilitation not observed, WHY? Field observations suggest that facilitation depends on recruitment rates – When recruitment is low Abundances too low for interactions to occur (short-term) – When recruitment is high Variable result: other experiments, saw facilitation In this experiment, mussel recruitment overwhelming, so even rugose rock surfaces acceptable

13. LTREB Goals Study designed to test change through (longer) time (10 yrs) – So these results are preliminary with respect to temporal changes Key result of ACE – Interaction strength and abundance of interactors is driven by subsidy rates along the capes

14. Acknowledgements A Huge Thanks To: The OSU PISCO Lab FRAs Jerod Sapp, Angela Johnson, Shawn Gerrity, Megan Poole, Lindy Hunter Tully Rohrer, Becky Focht, Kim Page- Albins SRAs Steven Cook, Emma Fraser, Peter McBride, Megan Urton, Marissa Duncan, Dani Smull, Kersten Schnurle, Kamala Earl, Alexander Carsh, Lacey Schrock-Purkey Grads Allie Barner, Liz Cerny-Chipman, Chenchen Shen, Sarah Close, Jenna Sulliven, Jessie Reimer Undergrads Silke Bachhuber, Kaitlyn Boze Photos by: Thomas Robinson Funding provided by: A special thanks to Christina Robinson

15. Questions?

17. CCLME (California Current Large Marine Ecosystem) Unique large scale study area Good place to study rocky intertidal – Why? Highly productive Diverse, highly dynamic biological communities Species interactions (facilitation, competition, and predation)