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- Dr. Linda Walters
Kali Standorf Department of Biology University of Central Florida
Urchins & Art Dr. Linda Walters Kali Standorf Department of - - PowerPoint PPT Presentation
Urchins & Art Dr. Linda Walters Kali Standorf Department of - - PowerPoint PPT Presentation
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
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What is a sea urchin?
- Echinoderms (~700 species)
– Radial symmetry – Water vascular system – Locomotion: tube feet – Found in shallows to deep sea
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More urchin info.
Reproduction
– Separate sexes – Spawn gametes into water column – 2 stage life-cycle (swimming larva + benthic adult)
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What do urchins eat? What eats urchins?
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Who eats sea urchins?
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Coral Reef Ecology Invasive Species Oyster Biology and Restoration
Marine Conservation Biology
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Ideal Coral Reef....
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Reality....
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?
How did this happen? 1) Loss of commercially important fish species 2) Anthropogenic nutrient enrichment 3) Increase in frequency/intensity of storms 4) Urchins
Phase Shift
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Diadema Die-Off in Caribbean
- Keystone herbivore (100/m2)
- All seaweed consumed
- Reefs: Corals dominated
- Near-extinction in early 1980s
- Reefs: Algae dominated
- Since 2000, Diadema returning
– Where? – Impact on corals? – Genetic bottleneck?
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Return to St. Thomas, USVI
- 1.6 ± 0.1/m2 (2006-2009)
- Nursery area: Airport
runway extension with 7 – 9/m2 up to 34/m2
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Can the return of Diadema to Caribbean waters shift us back to coral dominance?
Coral- Algal- Urchin Interactions
Porites astreoides Dictyota menstrualis Diadema
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Porites astreoides: Larval Collection
1 mm
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- Treatments: control, plastic mimic, alga
- 100 larvae (n = 10)
**Coral settlement significantly reduced if Dictyota present**
Field recruitment experiments (FL, USVI)
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Diadema Herbivory on Dictyota
- Consumed 30 – 85% biomass
- vernight
- Each urchin generated
8 – 53 fragments
- Fragment Viability: 61%
- Reattach < 24 hr
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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?
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Coral-Algal-Diadema Interactions
- 5 coral spat/tile
- Treatments: control,
mimic, algae with/without urchin
- Urchins feed
- vernight
1 2 3 4 5 A+U A-U M+U M-U C+U C-U Treatment Survival
*
Dictyota
- Foraging on Dictyota
killed 50% coral spat
- Foraging on 3 other
algae had no effect
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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