Final presentation draft 3.14.14
- 1. Purple Marsh Crab and Cordgrass Population Densities within South Carolina’s ACE Basin Alejandra Luna, Ramsey Millison, & Tara Poyer
- 2. Estuaries “Provide more services per unit area than any other ecosystem worldwide” (Gedan K. B. et al. 2011)
- 3. Salt Marsh Are transitional areas located along intertidal zones of estuaries (Wenner, 2010). Serve as shoreline erosion prevention.
- 4. Salt Marsh Die-Off in Cape Cod, Massachusetts Cordgrass die off on seaward edge of salt marsh Area critical to marsh development and maintenance. Decreasing barrier capabilities Gedan K. B. et al. 2011 Gedan K. B. et al. 2009
- 5. Ecosystem Population Relationships Secondary Consumer Primary Consumer Primary ProducerBlue Crab Purple Marsh Crab Cordgrass
- 6. Cordgrass Die Off Due to Purple Marsh Crab Found that all die-off areas had over 100 crab burrows/m2 Speculated overpopulation is due to overfishing of predators of purple marsh crab. (Holdredge et al. 2008) (Smith et al. 2013) = die-off marsh = healthy marsh 110 25
- 7. Purpose of the Study 1. Establish baseline populations for both cordgrass and purple marsh crab in relatively unfished areas. 2. Characterize population relationships between cordgrass and purple marsh crab. 3. Assess populations of other crab species present. ACE Basin
- 8. Our Study QUESTION: What are the population characteristics of purple marsh crab and cordgrass? How do they compare to those studied in Cape Cod, Massachusetts? HYPOTHESIS: As the population of purple marsh crab changes, the population of cordgrass will change. PREDICTION: As the population of purple marsh crab increases the population of cordgrass will decrease.
- 9. Survey Sites in the A.C.E. Basin
- 11. Population Surveys Burrow Counts (burrows >19mm) Excavation Sizes Botany Bay A- 6.67m x 0.7m Botany Bay B- 2.05m x 0.7m Ashepoo C- 3.09m x 0.7m Path HighTide Excavation (all crabs collected for analysis) 50m 0.5m2
- 12. Population Surveys Burrow Counts (burrows/m2) .5m2 Path HighTide Excavation Cordgrass counts (stalks/m2) 50m 0.5m2 0.5m2
- 13. Results: Correlative Analysis y = -3.2859x + 219.39 R = -0.336 0 50 100 150 200 250 300 350 0 5 10 15 20 25 30 35 40 45 Cordgrass(stalks/m2) Purple Marsh Crab (burrows/m2) Botany Bay A Botany Bay B Ashepoo
- 14. Population Density Comparisons Between South Carolina ACE Basin and Cape Cod Massachusetts 0 50 100 150 200 250 300 Ashepoo Botany Bay A Botany Bay B Stalks/m2 0 5 10 15 20 25 Ashepoo Botany Bay A Botany Bay B Burrows/m2 ACE Basin ‘Unhealthy’ Area Cape Cod ‘Healthy’ Area Cordgrass Purple Marsh Crab 270 stalks/m2 0 stalks/m2 25 burrows/m2 110 burrows/m2 (Holdredge et al. 2008)
- 15. Botany Bay A Botany Bay B Ashepoo male= = female= Results: Purple Marsh Crab Size/Sex Distribution male= 1 female=18 male= 6 female= 3 male= 18 female= 22 x̅ = 11.8 SD = 3.54 x̅ = 13.1 SD = 1.48 x̅ = 14.8 SD = 3.97 NumberofPurpleMarshCrabs
- 16. Results: Community Interactions Salt Marsh Mud Crab (Panopeus obesus) Atlantic Mud Crab (Panopeus herbstii) Squareback Marsh Crab (Armaces cinereum) Botany Bay A n=45 Botany Bay B n=44 Ashepoo n=72 Diet Predators Squareback marsh 11.11% 75.00 % 27.78% Cordgrass, leaves, aphids Birds, mammals, larger crabs Atlantic Mud Crab 6.67% 0 2.78% Periwinkle Snails Blue Crab (C. sapidus) Salt Marsh Mud 17.78% 2.27 % 0 Periwinkle Snails Blue Crab (C. sapidus) Purple Marsh Crab 64.44% 22.73% 69.44% Cordgrass Blue Crab (C. sapidus)
- 17. Salt Marsh Mud Crab Atlantic Mud Crab Squareback Marsh Crab Blue Crab Purple Marsh Crab Cordgrass Periwinkle Snail
- 18. Conclusions Purple marsh crab and cordgrass populations are equally healthy in comparison to the healthy salt marshes of Cape Cod. Purple marsh crab populations appear to affect cordgrass populations, however more populations assessments are needed throughout the ACE basin
- 19. Acknowledgements DePaul University Department of Biological Sciences for funding this research. Special thanks to South Carolina’s Department of Natural Resources for allowing us to work in the salt marshes and providing room and board during our research.
Editor's Notes
- #2: Change title
- #3: Estuaries: A mixing of saltwater and freshwater Services: nurseries for commercial and naturally occurring fish. Important for their biochemical and pollutant filtering capabilities. Include habitats like the Maritime Forest and Salt Marsh: in the photo to the right is an example of a salt marsh
- #4: Temperature, salinity, and water depth constantly change due the rise and fall of tides Salt marshes have a diverse variety of organisms
- #6: Talk about Top down systems (switch orientation of arrows)
- #7: (maybe add actual numbers in die off graph: 110 for die off, 25 for healthy)
- #10: Put circle a little to the left and a little down, and make it smaller, Please! Make the other circle smaller too.
- #14: Not Correlation, this is a Regression. Also say how does this compares to MA?
- #15: Tara fix the axis on these please! Also we need to do a single sample t-test in order to see significance in differences. [add error bars!]-make these bigger!!!
- #16: Not sure what you guys want to do about the picture distortion. Also for width means and standard dev. Should we include the <11 mm data in calculations. For now I’m going to include it. Also Tara could you do the alignment thing for the mean and SD. Thanks.
- #17: Put circles around the bolded numbers. Not sure where the circles should go. I think the circles need to emphasize the percentage of Squareback crabs in Botany Bay B, the percentage of purple marsh in Ashepoo and Botany Bay A. Circle also need to be animated.
- #18: Switch arrows to pointing up from cordgrass, and extend arrows to look like arrow from blue crap to salt marsh mud crab. Should all the arrows be the same size?
- #19: Cant say stable here for first point. And unsure of last point.