1. Julius A. Ellrich, Ricardo A. Scrosati & Markus Molis
Predator non-consumptive effects
on prey recruitment weaken with prey density
Julius A. Ellrich, Ricardo A. Scrosati & Markus Molis
BREMEN
UNIVERSITY

2. Consumptive effects (CEs) Non-consumptive effects (NCEs)
Predator consumptive & non-consumptive effects
Predator
Consumptive effects (CEs)
(killing)
Non-consumptive effects (NCEs)
(chemical cues)
Prey
NCEs change traits in prey: activity, behaviour, morphology…
(e.g. Ferrari et al. 2010, Brönmark & Hansson 2012, Ohgushi et al. 2012)
NCEs often stronger than CEs
(Preisser et al. 2005, Trussell et al. 2006)
Do NCEs affect prey demographic rates?

3. Model System benthic pelagic Barnacle Life-Cycle
Predatory Dogwhelks (Nucella lapillus)
Barnacles (Semibalanus balanoides)
N Atlantic coasts
pelagic

4.  Population replenishment & persistence
Settlement & Recruitment
Nova Scotia: May & June
 Population replenishment & persistence

5. Do NCEs affect prey demographic rates?
Predator cues…
repel larvae (lobster, crabs, blue mussels)
(Bourget et al. 1993, Tapia-Lewin & Pardo 2014, Morello & Yund BEM 2015)
decrease settlement (barnacles, crabs)
(Johnson & Strathmann 1989, Welch et al. 1997)
decrease early recruitment (barnacles)
(Johnson & Strathmann 1989)
limited to max. 14 day long periods
recruits accumulate over several weeks to months
(e.g. Beermann et al. 2013, Menge & Menge 2013)
 Are there factors that weaken predator NCEs?

6. Barnacle Recruit Density
Cyprids are attracted by:
Recent settlers & recruits
(Hills & Thomason 1998, Shanks 2009)
Cyprid footprints
(Yule & Walker 1985, Clare et al. 1994)
Attractive chemical cues
Arthropodin, Settlement-Inducing Protein Complex (SIPC)
(e.g. Crisp & Meadows 1962, Matsumura et al. 2000, Dreanno et al. 2006)
 High recruit density may weaken predator NCEs
Recruits & Cyprids1
1http://

7. Food Supply Food supply may indirectly weaken predator NCEs
Phytoplankton abundance
enhances:
Larval development
(Emlet & Sadro 2006)
Recruitment
(Menge et al. 2003, Cole et al. 2011)
Food supply may indirectly weaken predator NCEs
Feeding barnacle2
2http://zottoli.wordpress.com/saltmarshes/mud-flats-zone-1/

8. Barnacle Adult Presence
Enhance settlement & recruitment
(Bertness et al. 1992, Beermann et al. 2013)
Chemical cues: Arthropodin, SIPC
(Crisp & Meadows 1962, Matsumura et al. 2000)
 Adult presence may weaken
predator NCEs

9. Barnacle recruit density
Hypotheses
Barnacle recruit density
Predator NCEs limit barnacle recruitment under low recruit density
High barnacle recruit density weakens predator NCEs

10. Barnacle recruit density
Hypotheses
Barnacle recruit density
Adult barnacle presence weakens predator NCEs

11. Study System ↑ N
Gulf of St. Lawrence
Nova Scotia
Atlantic Ocean

12. Food Supply Chlorophyll a concentration (mg m-3) Gulf 2011 Atlantic
2011: six times higher, 2013: similar, intermediate levels
Gulf
2011
Atlantic
2011
Gulf
2013
Atlantic
2013
nasa.gov/giovanni/
M±SE

13. Dogwhelk Treatments
10 dogwhelks present
dogwhelks absent

14. Cage Design
25 cm
40 cm

15. Effects of Barnacle Recruits Comparative Experimental Approach (Menge et al. 1994)
Blocks: 1
Random, 6 levels
(2011), 8 levels (2013) 8
Dogwhelks:
Fixed, 2 levels
Replicates: 1 2
Response variable: recruit density
4 separate 2-factorial ANOVAs

16. Adult Barnacle Treatments
15 Adult barnacles present
Adult barnacles absent
Phytoplankton abundance mg chl-a m-3: 1.5 (2012); 3.2 (2013)

17. Effects of Barnacle Adults
Year:
2012
2013
Random, 2 levels
Blocks: 1 6
Random, 6 levels
Adult barnacles:
Fixed, 2 levels
Dogwhelks:
Fixed, 2 levels
Replicates: 1 2
Response variable: recruit density
4-factorial ANOVA, Tukey HSD test

18. Effects of Barnacle Recruits
Barnacle recruit density (individuals dm-2)
Gulf 2011
Gulf 2013
Atlantic 2011
Atlantic 2013
n.s.
Dogwhelks
No Dogwhelks * * *
Chl-a (mg m-3)
7.1
1.2
4.7
4.3
M ± SE
Ellrich, Scrosati & Molis (2015) Ecology

19. Effects of Barnacle Adults
Dogwhelks present
Dogwhelks absent
Dogwhelks
No Dogwhelks
Barnacle recruit rensity (individuals dm-2)
M ± SE
Ellrich, Romoth, Scrosati & Molis (submitted)

20. Conclusions Dogwhelk NCEs limit barnacle recruitment
High barnacle recruit density and adult presence neutralized dogwhelk NCEs
- Attractive conspecific cues may counteract predator cues
- Cyprids may experience lower predation risk
per capita in presence of conspecifics
High recruit density related to high phytoplankton abundance
- Bottom-up factor may determine occurrence of predator NCEs

21. Conclusions
Attractive adult cues present in many benthic marine invertebrates
(arthropods, molluscs, polychaetes, echinoderms, tunicates,
e.g. Puglisi et al. 2014)
- Adult presence neutralizing predator NCEs may be common
- Exceptions: Cannibalistic species?

22. Acknowledgements Field: Katharina Romoth Willy Petzold Arne Beermann
Patrick Comtois
Elise Keppel
Lab:
Werner Schnepf
Steven MacDonald
David Risk
Vince Arsenault
Lorena Arribas
Funding:
Grants from Canada Research Chairs (CRC), Canada Foundation of Innovation (CFI), and Natural Sciences and Engineering Research Council (NSERC, Discovery Grant) to Ricardo A. Scrosati.
Ph.D. scholarships from the Stiftung für Kanada-Studien (SKS) and the German Academic Exchange Service (DAAD) to Julius A. Ellrich.
K. Romoth & W. Petzold
A. Beermann
CRC
CFI
NSERC
SKS

23. Thank You!