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Urchins & Art Dr. Linda Walters Kali Standorf Department of - PowerPoint PPT Presentation

Mar 13, 2023 •398 likes •606 views

Urchins & Art Dr. Linda Walters Kali Standorf Department of Biology University of Central Florida Urchin Art What is a sea urchin? Echinoderms (~700 species) Radial symmetry Water vascular system Locomotion: tube feet

  1. Urchins & Art Dr. Linda Walters Kali Standorf Department of Biology University of Central Florida

  2. Urchin Art

  3. What is a sea urchin? • Echinoderms (~700 species) – Radial symmetry – Water vascular system – Locomotion: tube feet – Found in shallows to deep sea

  4. More urchin info. Reproduction – Separate sexes – Spawn gametes into water column – 2 stage life-cycle (swimming larva + benthic adult)

  5. What do urchins eat? What eats urchins?

  6. Who eats sea urchins?

  7. Marine Conservation Biology Coral Reef Ecology Oyster Biology and Restoration Invasive Species

  8. Ideal Coral Reef....

  9. Reality....

  10. ? Phase Shift How did this happen? 1) Loss of commercially important fish species 2) Anthropogenic nutrient enrichment 3) Increase in frequency/intensity of storms 4) Urchins

  11. Diadema Die-Off in Caribbean • Keystone herbivore (100/m 2 ) • All seaweed consumed • Reefs: Corals dominated • Near-extinction in early 1980s • Reefs: Algae dominated • Since 2000 , Diadema returning – Where? – Impact on corals? – Genetic bottleneck?

  12. Return to St. Thomas, USVI • 1.6 ± 0.1/m 2 (2006-2009) • Nursery area: Airport runway extension with 7 – 9/m 2 up to 34/m 2

  13. Can the return of Diadema to Caribbean waters shift us back to coral dominance? Diadema Coral- Algal- Porites astreoides Urchin Interactions Dictyota menstrualis

  14. Porites astreoides: Larval Collection 1 mm

  15. Field recruitment experiments (FL, USVI) •Treatments: control, plastic mimic, alga • 100 larvae (n = 10) **Coral settlement significantly reduced if Dictyota present**

  16. Diadema Herbivory on Dictyota • Consumed 30 – 85% biomass overnight • Each urchin generated 8 – 53 fragments • Fragment Viability: 61% • Reattach < 24 hr

  17. Are there enough urchins to consume enough algae to clear areas for corals to settle and grow? Could the urchins themselves damage coral spat when foraging?

  18. Coral-Algal- Diadema Interactions • 5 coral spat/tile • Treatments: control, mimic, algae with/without urchin • Urchins feed overnight Dictyota • Foraging on Dictyota 5 4 * killed 50% coral spat Survival 3 2 • Foraging on 3 other 1 algae had no effect 0 A+U A-U M+U M-U C+U C-U Treatment

  19. Genetic Bottleneck? Kali’s project • How much genetic diversity is there in these returning populations? – Bottleneck (limited DNA diversity)? – Mixing from ocean currents? – Molecular techniques to look at DNA from 8 populations – 3 islands, both juveniles and adults

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