5/13/2014. Costs and benefits of intertidal algal epiphytism EPIPHYTES. General Benefits Experienced by Epiphytes. Laura Anderson Martone Lab

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Experienced by Epiphytes Epiphytes Increased settlement space Increased access to

1 Costs and benefits of intertidal algal epiphytism EPIPHYTES Laura Anderson Martone Lab UBC Vancouver, CAN Organisms that grow on plants (as opposed to rock/soil) General Benefits Experienced by Epiphytes Epiphytes Increased settlement space Increased access to light/nutrients Decreased herbivory Hosts: substrate only Photosynthetic, not parasitic Kyle Demes 1

by Hosts STUDY SYSTEM Epiphyte (brown): Soranthera ulvoidea Host (red): Odonthalia floccosa pendiva.

2 ? Increased settlement space Increased access to light/nutrients Increased competition for light/nutrients Decreased reproductive output Increased dislodgement Introduction General Benefits Experienced by Epiphytes Decreased herbivory General Costs Experienced by Hosts STUDY SYSTEM Epiphyte (brown): Soranthera ulvoidea Host (red): Odonthalia floccosa pendiva.com Biomechanics Ecology Summary STUDY SYSTEM STUDY SYSTEM gulfislandvacationrentals.com vancouverislandbritishcolumbia.com vancouverislandbritishcolumbia.com 2

3 OUTLINE Part I: Biomechanical Consequences Part I: Biomechanical Consequences art.com Part II: Other Ecological Interactions Becca Kordas art.com Biomechanical Consequences 1. Do epiphytes increase drag on hosts? 2. Do epiphytes increase host dislodgement risk? 3. Do epiphytes benefit by being epiphytic? 4. Do epiphytes or hosts break first? Biomechanical Consequences 1. Do epiphytes increase drag on hosts? 2. Do epiphytes increase host dislodgement risk? 3. Do epiphytes benefit by being epiphytic? 4. Do epiphytes or hosts break first? 3

4 Drag Force (N) ± SE Drag Force (N) ± SE Host with epiphytes METHODS Measured drag at different velocities in flume.6..4 RESULTS.3.2 Hosts alone.1 Host alone Cathryn Clarke Murray Velocity (ms -1 ) * RESULTS Epiphytes increase drag on host * * * Hosts with epiphytes * Hosts alone Velocity (ms -1 ) * Paired t-test : p<. ~% increase * Biomechanical Consequences 1. Do epiphytes increase drag on hosts? 2. Do epiphytes increase host dislodgement risk? 3. Do epiphytes benefit by being epiphytic? 4. Do epiphytes or hosts break first? 4

Drag Force (N) Drag Force (N) Drag Force (N) METHODS Measured host removal forces in field with spring scale Kieran Oudshoorn enasco.com METHODS Measured drag on hosts in flume.4.4 Host alone.3.3.2.

5 Drag Force (N) Drag Force (N) Drag Force (N) METHODS Measured host removal forces in field with spring scale Kieran Oudshoorn enasco.com METHODS Measured drag on hosts in flume.4.4 Host alone Flume data Velocity in Flume (ms -1 ) METHODS Predicted dislodgement velocities for hosts with and without epiphytes Field removal force Flume data Host alone Velocity (ms -1 ) Predicted breakage velocity METHODS Predicted dislodgement velocities for hosts with and without epiphytes Field removal force Flume data Host with epiphytes Host alone Max velocities experienced at field site Velocity (ms -1 ) Predicted breakage velocity

6 Drag Force (N) Drag Force (N) Field removal force RESULTS Epiphytes decrease velocity to break hosts Paired t-test: t=.94, df=13, p<.1 Flume data Host with epiphytes Host alone Max velocities experienced at field site Velocity (ms -1 ) Predicted breakage velocity Field removal force RESULTS Epiphytes increase host dislodgement risk Paired t-test: t=.94, df=13, p<.1 Flume data Host with epiphytes Host alone Max velocities experienced at field site Velocity (ms -1 ) Predicted breakage velocity Biomechanical Consequences METHODS Measured Lifesaver dissolution at different flume velocities 1. Do epiphytes increase drag on hosts? 2. Do epiphytes increase host dislodgement risk? 3. Do epiphytes benefit by being epiphytic? 4. Do epiphytes or hosts break first? Alone Attached to host Cathryn Clarke Murray 1 Minute Lifesaver mass loss = proxy for flow experienced by epis 6

Average Mass Lost (g) Average Mass Lost (g) 3 RESULTS RESULTS Lifesavers experience less flow when on hosts 3 2. 2 (R² =.99) Lifesavers alone 2. 2 * * (R² =.99 Lifesavers alone 1.

7 Average Mass Lost (g) Average Mass Lost (g) 3 RESULTS RESULTS Lifesavers experience less flow when on hosts (R² =.99) Lifesavers alone 2. 2 * * (R² =.99 Lifesavers alone * Lifesavers on host (R ² =.9 7 ) 1 1 * Velocity (ms -1) Velocity (ms -1) ANOVAs, P<.3 at all velocities Epiphytes of a certain size can exist in areas that experience specific water velocities 3 Epiphytes of a certain size can exist in areas that experience specific water velocities Predicted breakage velocity (ms -1) 2 Predicted breakage velocity (ms -1) Cathryn Clarke Murray 1 1 Epiphy tes on hos ts Epiphy tes not on hos ts (theoretic al) Epiphyte area (cm 2) Epiphy tes not on hos ts (theoretic al) Epiphyte area (cm 2) 7

Predicted breakage velocity (ms -1) Predicted breakage velocity (ms -1) 3 Epiphytes on hosts can grow larger and/or exist in areas of greater wave exposure 3 2 2 2 2 1 1 1 M ax water v elocity in the

8 Predicted breakage velocity (ms -1) Predicted breakage velocity (ms -1) 3 Epiphytes on hosts can grow larger and/or exist in areas of greater wave exposure M ax water v elocity in the field 1 M ax water v elocity in the field Epiphy tes on hos ts Epiphy tes on hos ts Epiphy tes not on hos ts (theoretic al) Epiphyte area (cm 2) Epiphy tes not on hos ts (theoretic al) Epiphyte area (cm 2) Larger algae = more photosynthesis, more reproduction, etc Predicted breakage velocity (ms -1) Larges t obs erv ed epiphy te Epiphyte area (cm 2) M ax water v elocity in the field Epiphy tes on hos ts Epiphy tes not on hos ts Biomechanical Consequences 1. Do epiphytes increase drag on hosts? 2. Do epiphytes increase host dislodgement risk? 3. Do epiphytes benefit by being epiphytic? 4. Do epiphytes or hosts break first? 8

METHODS enasco.com Predicted Breakage Velocities (ms -1 ) Sample Epiphytized Host Weakest Epiphyte seaweedsofalaska.com A 1 2.7 B 7.6 4.

9 METHODS enasco.com Predicted Breakage Velocities (ms -1 ) Sample Epiphytized Host Weakest Epiphyte seaweedsofalaska.com A B Measured epiphyte removal forces with spring scale Predicted velocities to dislodge epiphytes (with corrected force measurements), compared these with host predictions C D E F G H I J K L 9..2 M 4..4 N host predicted to break before epiphyte Epiphytes are more likely to dislodge from hosts than hosts are to dislodge from the substratum Predicted Breakage Velocities (ms -1 ) Predicted Breakage Velocities (ms -1 ) Sample Epiphytized Host Weakest Epiphyte Sample Epiphytized Host Weakest Epiphyte A B C D E F G H I J K L 9..2 Highest average wave velocity between May -Nov:.6 m/s ± 1.9 SE A B C D E F G H I J K L 9..2 Paired t-test: t=.61, d.f.=13, P>.1 Half of the hosts had at least one epiphyte break off in the flume M 4..4 M 4..4 N N

Anderson, L. M. and P. T. Martone. 214. Biomechanical consequences of epiphytism in intertidal macroalgae. J. Exp. Biol. 217: 1167-1174.

10 Anderson, L. M. and P. T. Martone Biomechanical consequences of epiphytism in intertidal macroalgae. J. Exp. Biol. 217: Searched site for drift algae SUMMARY Biomechanical Consequences 1. Epiphytes increase drag on hosts SUMMARY Biomechanical Consequences 1. Epiphytes increase drag on hosts 2. Epiphytes increase host dislodgement risk 1

Epiphytes are more likely to dislodge than hosts Part I: Biomechanical Consequences Part II: Other Ecological Interactions art.

11 SUMMARY Biomechanical Consequences 1. Epiphytes increase drag on hosts 2. Epiphytes increase host dislodgement risk 3. Epiphytes benefit by experiencing less flow when on hosts SUMMARY Biomechanical Consequences 1. Epiphytes increase drag on hosts 2. Epiphytes increase host dislodgement risk 3. Epiphytes benefit by experiencing less flow when on hosts 4. Epiphytes are more likely to dislodge than hosts Part I: Biomechanical Consequences Part II: Other Ecological Interactions art.com Part II: Other Ecological Interactions Becca Kordas art.com 11

Net Photosynthesis Other Ecological Interactions 1. Do epiphytes shade hosts & decrease light availability/do hosts elevate epiphytes & increase light availability? 2.

12 Net Photosynthesis Other Ecological Interactions 1. Do epiphytes shade hosts & decrease light availability/do hosts elevate epiphytes & increase light availability? 2. Do epiphytes decrease host desiccation? 3. Do epiphytes decrease herbivore grazing of hosts? Other Ecological Interactions 1. Do epiphytes shade hosts & decrease light availability/do hosts elevate epiphytes & increase light availability? 2. Do epiphytes decrease host desiccation? 3. Do epiphytes decrease herbivore grazing of hosts? PHOTOSYNTHESIS METHODS n=1 Photosynthesis VS Irradiance Curves Saturation Irradiance (Ik) Bess Kennedy Irradiance 12

13 Net Oxygen Flu x (μmol O2 gdw -1 hr -1 ) ± SE Net Oxygen Flu x (μmol O2 gdw -1 hr -1 ) ± SE Epiphyte Host Host Net Oxygen Flu x (μmol O2 gdw -1 hr -1 ) ± SE Net Oxygen Flu x (μmol O2 gdw -1 hr -1 ) ± SE Epiphyte Epiphyte Host host Avg. irradiance under algal canopy in field ± sd host I k -2 3 I k 2 epiphyte 2 epiphyte Irradiance (μmol m -2 s -1 ) -2 Irradiance (μmol m -2 s -1 ) Host 2 light access 4 is 6 not affected I k Avg. irradiance under algal canopy in field ± sd Irradiance (μmol m -2 s -1 ) two sample t-test: t = 1.388, df = 17, p >.2 by epiphyte cover Irradiance (μmol m -2 s -1 ) host I k Epiphytes do not need to grow on hosts to access light two sample t-test:t =.96, df = 17, p > Avg. irradiance -2 under canopy in field ± sd Irradiance (μmol m -2 s -1 ) epiphyte 13

% Relative Water Content of Host ± SE % Relative Water Content of Host ± SE Other Ecological Interactions DESICCATION METHODS weigh 1. Do epiphytes decrease host access to light? 2.

14 % Relative Water Content of Host ± SE % Relative Water Content of Host ± SE Other Ecological Interactions DESICCATION METHODS weigh 1. Do epiphytes decrease host access to light? 2. Do epiphytes decrease host desiccation? 3. Do epiphytes decrease herbivore grazing of hosts? weigh recombine Recorded host mass loss every 1 min for 1 hr 1 8 Epiphytes delay host desiccation % RWC Hosts with epiphytes Hosts only Time (min) Hosts only Time (min) Repeated measures ANOVA Source df F p-value time*treatment n=1; log transformed 14

% Change in Algal Mass ± 9% CI % Change in Algal Mass ± 9% CI Other Ecological Interactions 1. Do epiphytes decrease host access to light? 2. Do epiphytes decrease host desiccation? 3.

com/photos/ophis Different numbers of grazers for different amounts of time Control: Host Epiphyte n=1 Amphipods www.flickr.

15 % Change in Algal Mass ± 9% CI % Change in Algal Mass ± 9% CI Other Ecological Interactions 1. Do epiphytes decrease host access to light? 2. Do epiphytes decrease host desiccation? 3. Do epiphytes decrease herbivore grazing of hosts? Treatment: Host Epiphyte Herbivore(s) HERBIVORY METHODS Amphipods Idotea Littorina Different numbers of grazers for different amounts of time Control: Host Epiphyte n=1 Amphipods photos/ophis Idotea Littorina Without Herbivores EPIPHYTE HOST Control With Herbivores n=1 Amphipods photos/ophis Idotea Littorina Without Herbivores EPIPHYTE HOST With Herbivores Treatment Source df p-value treatment*algae 1.1 Source df p-value treatment 1.1 algae 1.1 treatment*algae 1.8 Source df p-value treatment*algae 1.1 a b 1

16 Average herbivore abundance per quadrat ± 9% CI % Change in Host Mass ± SE HERBIVORY METHODS Amphipods Idotea Littorina Amphipods eat more host tissue in the absence of epiphytes 2 Herbivore -2 Different numbers of grazers for different amounts of time -4 Amphipods Idotea Littorina Treatment: Host Epiphyte Herbivore(s) Control: Host Epiphyte Paired t-test: t= df=9 p=.39* t=-.332 df=9 p=.8 Host Before Epiphyte Removal Host After Epiphyte Removal t=.448 df=9 p=.7 Amphipods are more abundant than other herbivorous invertebrates at collection site Kruskal-Wallis: 2.74, df=2 p<.1 SUMMARY Other Ecological Interactions 1. NO, epiphytes do not decrease host access to light/epiphytes do not necessarily benefit by being elevated 4 2 Amphipods Littorina Idotea Herbivore 16

SUMMARY Other Ecological Interactions 1. NO, epiphytes do not decrease host access to light/epiphytes do not necessarily benefit by being elevated 2.

17 SUMMARY Other Ecological Interactions 1. NO, epiphytes do not decrease host access to light/epiphytes do not necessarily benefit by being elevated 2. Epiphytes decrease host desiccation SUMMARY Other Ecological Interactions 1. NO, epiphytes do not decrease host access to light/epiphytes do not necessarily benefit by being elevated 2. Epiphytes decrease host desiccation 3. Herbivores prefer grazing epiphytes; amphipods eat more host in the absence of epiphytes SUMMARY Questions? Biomechanical Hosts Drag/ Dislodgement Epiphytes + Reduced flow Ecological + Desiccation Herbivory = Light access Herbivory THANKS TO: Patrick Martone, Chris Harley, Brian Leander, Rob DeWreede, Paul Gabrielson, Mark Denny, Kyle Demes, Becca Guenther, Bess Kennedy, Sam Starko, Becca Kordas, Kyra Janot, Barry Clayman, Jen Jorve, Katherine Clark-Murray, George Hicks, Roland Stull 17

Force on Hosts (N) Force on Host (N) Drag increases with size and velocity..4.3 R² =.6113 3.2 Predicted Breakage Velocity (ms -1) 3.1 1 m/s 2 2 4 6 8 1 Size (cm²)..4 2 1 1.3.2.1 Hosts Alone Hosts with Epiphytes.

18 Force on Hosts (N) Force on Host (N) Drag increases with size and velocity..4.3 R² = Predicted Breakage Velocity (ms -1) m/s Size (cm²) Hosts Alone Hosts with Epiphytes Velocity (m/s) t=.211, d.f.=13, P<.1 METHODS Measured drag at different velocities in flume DRAGtogether Cathryn Clarke Murray DRAGepi DRAGhost 18

Removal Force (N) ± SE % Relative Water Content Subsequent Branch Removal Forces secondary tertiary enasco.com 1

19 Removal Force (N) ± SE % Relative Water Content Subsequent Branch Removal Forces secondary tertiary enasco.com A primary secondary tertiary Branch Introduction Questions B C primary ANOVA Log transformed df=2, n=1,17,24 F-ratio: 3.84 p<.1 Tukey s HSD Biomechanics Ecology Summary Time (min) Temp: 19.7 C Relative Humidity: 8.9 % Wind Speed: 6.8 km/hr Irradiance: 2,447.9 μmol m -2 s -1 Epiphytes Alone H osts with Epiphytes H osts Alone 19

Feeding Rate (g/herbivore hr -1 ).2 m -2 ) HERBIVORY METHODS Idotea graze the fastest and apply the most grazing pressure/area.12.1.8 31 quadrats along 4m of the mid-low intertidal zone.

20 Feeding Rate (g/herbivore hr -1 ).2 m -2 ) HERBIVORY METHODS Idotea graze the fastest and apply the most grazing pressure/area quadrats along 4m of the mid-low intertidal zone Epiphyte H ost Amphipods Littorina Idotea H erbivore Grazing Pressure (g hr 1 herbivore Epiphyte H ost Amphipods Littorina Idotea H erbivore 2

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