Effects of erosion on subtidal communities in Elkhorn Slough. Catalina E. Reyes Moss Landing Marine Laboratories January 20, 2010

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1 Effects of erosion on subtidal communities in Elkhorn Slough Catalina E. Reyes Moss Landing Marine Laboratories January 2, 21

2 Estuarine Habitats Estuaries Low relief sedimentary Little to no rocky substrate Biological structures important in generating habitats

3 Distribution of Erosional Change in Elkhorn Slough Data from Seafloor Mapping Lab at the California State University Monterey Bay.

4 Goal of Study The overall goal of this study is to look at how differential amounts of erosion effect the distribution of subtidal habitats. Question: Does percent cover of subtidal habitats vary across erosion classes?

5 Methods Habitat Types Shell Debris Red Algae Green Algae Seagrass

6 Methods Habitat Types Exposed Substrate No Biological Cover

7 Methods / Erosional Classifications Bathymetric Change Between 21 and 25 N High Erosion > -2.m Low Erosion -2.m to -.5m No Change -.5m to.5 m Deposition >.5 m Data from Seafloor Mapping Lab at the California State University Monterey Bay.

8 Methods Data Collection Photos collected with drop camera within the 4 identified erosion classes Photos analyzed for percent cover 4 Seasons Summer 8 (7/11/8-7/14/8) Fall 8 (1/7/8 1/12/8) Winter 9 (1/9/9 1/14/9) Spring 9 (4/6/9 4/1/9)

9 Methods Data Analysis Mean Percent Cover -One way two factor ANOVA α.5 Fisher LSD multiple comparison test α.5

10 Results

11 Results ANOVA % Cover of shell Debris ( SE) Shell Debris High Erosion Low Erosion p-value =.9 No Change Deposition Summer 8 Fall 8 Winter 9 Spring 9

12 Results Fisher LSD Shell Debris Across Seasons % Cover ( SE) High Erosion NS Low Erosion A,B A A B 1 No Change Deposition % Cover ( SE) A Summer 8 A A,B B Fall 8 Winter 9 Spring 9 B Summer 8 B A A Fall 8 Winter 9 Spring 9

13 Results ANOVA % Cover of seagrass ( SE) p =.36 High Erosion Low Erosion No Change Deposition Seagrass Summer 8 Fall 8 Winter 9 Spring 9

14 Results Fishers LSD % Cover of Seagrass ( SE) Seagrass / Within Seasons B A Summer 8 Fall 8 Winter 9 Spring 9 Season High Erosion Low Erosion No Change Deposition B B B B A

15 Results ANOVA p-value =.1 Green algae High Erosion Low Erosion % Cover of green algae( SE) No Change Deposition Summer 8 Fall 8 Winter 9 Spring 9

16 Results Fisher LSD Green Algae Seasonally in No Change % Cover of green algae ( SE) A A,B B C Summer 8 Fall 8 Winter 9 Spring 9

17 Results ANOVA Red Algae % Cover of red algae ( SE) p =.28 High Erosion Low Erosion No Change Deposition 1 1 Summer 8 Fall 8 Winter 9 Spring 9

18 Results ANOVA Exposed Substrate % Cover of Exposed Substrate ( SE) p-value =.1 High Erosion Low Erosion No Change Deposition Summer 8 Fall 8 Winter 9 Spring 9 *includes clay

19 Results Fisher LSD Exposed Substrate Within Seasons % Cover Exposed Substrate ( SE) A Summer 8 Fall 8 A A A B B B B % Cover Exposed Substrate ( SE) High Erosion Winter 9 Low Erosion NS No Change Deposition High Erosion Spring 9 Low Erosion No Change NS Deposition

20 Summary Does percent cover of subtidal habitats vary across erosion classes? Shell Debris No, but seasonal component Green Algae - No, but seasonal component

21 Summary Does percent cover of subtidal habitat vary across erosion classes? Seagrass Yes (absent or rare in high and low erosion) Red Algae Yes (absent or rare high erosion) Exposed Substrate Yes, (highest in high and low erosion classes during Summer 8 and Fall 8)

22 Conclusions Erosion will result in the expansion of exposed substrate Shell debris and green algae may be the only biological habitat types that will expand with erosion Where erosion expands loss of red algae and seagrass will occur

23 Significance of Project Now we have a baseline of the distribution of subtidal habitats We know which subtidal habitats we can expect to increase or decrease if erosion continues.

24 Acknowledgements Funding NOAA Environmental Entrepreneurship Program Committee Members: Michael Graham Ivano Aiello Fraka Harmsen Rikk Kvitek Field and other Technical Help Miguel Romo, Selena McMillian, Rosemary Romero, Jasmine Ruvalcaba, Paul Tompkins, Megan Wehrenberg, Ben Perlman, Nora Grant, Sonya Sankaran, Sara Hutto, Arley Muth, Kyle Glenn, Vince Christian, Hillary Hayford, Shaara Ainsley, Melinda Nakagawa, Bill Watson, Kamille Hammerstrom, Chante Davis, Chris Scianni, Jerimiah Brower, Charlie Endris, Gala Wagnar