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UNDERSTANDING THE ROLE OF HERBIVORY AND PREDATOR/PREY INTERACTIONS TO GUIDE THE DEVELOPMENT OF A COMPREHENSIVE CORAL
REEF RESTORATION STRATEGY
William Sharp and Gabriel Delgado
Florida Fish & Wildlife Conservation Commission Fish & Wildlife Research Institute
2796 Overseas Hwy, Suite 119 Marathon, FL 33050
1965
1979
1988
2001
2010
Images: Gene Shinn. Tropical Treasures - South Florida Marine Environments
2002
From: Gardner et al 2003
Present Situation of Florida’s Coral Reef Ecosystem
Florida’s coral reefs have become degraded due to numerous stressors
Coral diseases Loss of dominant herbivore Poor water quality Marine debris Climate change
What can we do?
Manage to maintain biodiversity —Establish Marine Protected Areas
Reduce land-based sources of impact
Reduce direct impacts from human usage
©CRF/Tim Grolimund
But is this enough?
Increasing acceptance that restoring Florida’s coral reef ecosystem will require active restoration efforts
©CRF/Tim Grolimund
Coral Restoration
Restoring the physical reef structure is the necessary first step toward coral reef ecosystem restoration
Coral Nurseries We have established two coral
nurseries in the middle Florida Keys
Part of a network of nurseries throughout Florida and the Caribbean
Stocked with staghorn coral
Herbivory ‒ Long-Spined Sea Urchin Research
Other Coral Reef Ecosystem Restoration Research
Predator/Prey Dynamics – Corallivorous gastropods & a potential predator
Herbivory ‒ Long-Spined Sea Urchin Research
Other Coral Reef Ecosystem Restoration Research
Predator/Prey Dynamics – Corallivorous gastropods & a potential predator
Long-Spined Urchin Research
Diadema antillarum
Keystone coral reef herbivore
Caribbean-wide mortality event in 1980s
Recovery identified as necessary to improve health of coral reef ecosystem
Importance of the species
Long-Spined Urchin Research
2009 – A cohort of Diadema successfully cultured to early-benthic-juvenile stage
Can hatchery-produced Diadema be used as part of a comprehensive coral reef ecosystem restoration strategy?
First question -- Are hatchery-produced individuals ecologically competent?
Sheltering Behavior
D antillarum typically exhibit diurnal sheltering behavior
Compare sheltering behavior of initial hatchery-reared cohort & wild individuals
Laboratory trails in mesocosms with shelter provided
Replicated trials with wild and hatchery urchins in separate mesocosms; Trials with wild and hatchery urchins in the same mesocosms
15 cm
Sheltering Behavior
Day 4 3 2 1
perc
enta
ge in
shel
ter (
+ 1
se) 100
50
0
Night 4 3 2 1
wild hatchery
wild & hatchery in separate mesocosms
P = 0.008 NS
Behavior - Shelter Usage
wild & hatchery mixed in same mesocosm
P = 0.003
5 4 3 2 1 5 4 3 2 1
Day Night
perc
enta
ge in
shel
ter (
+ 1
se) 100
50
0
P = 0.045 wild hatchery
Behavior - Shelter Usage
Behavior - Shelter Usage Next hatchery-bred cohort
Shelter provided until
transported to FWC lab ~ 5 mm test diameter
Behavior - Shelter Usage
“Shoebox Experiments”
Hatchery-bred urchins given appropriately scaled light/dark choice
Behavior - Shelter Usage “Shoebox
Experiments” Hatchery-bred
urchins given appropriately scaled light/dark choice
Observed diurnal differences in sheltering behavior
5555 5555N =
DATE
06/05/1106/04/1106/03/1106/02/1106/01/11
Mea
n (+
- 1 S
E) %
in S
helte
r
1.2
1.0
.8
.6
.4
.2
0.0
Day
Night
Behavior - Shelter Usage Shoebox - Day Shoebox - Night
NS NS
Long-Spined Urchin Research Chemotactic responses to predation threat
Wild urchins will avoid the water-borne chemical signal of a predator
From Kintzing 2010
Approach modeled after Kintzing (2010) Tracked overall movement
of hatchery-bred urchins in response to lobster chemical cue
Chemotactic Responses to Predation Threat
Chemotactic Responses to Predation Threat
Hatchery-bred responded similarly to wild urchins as reported by Kintzing (2010)
Summary Sheltering Behavior
Grow-out conditions affect sheltering behavior; juvenile urchins deprived of shelter do not exhibit diurnal sheltering behavior
When provided appropriately scaled shelter during the husbandry process, hatchery-bred urchins exhibit expected diurnal sheltering behavior
Density-dependent effects are being evaluated
Chemotactic Responses to Predation
Hatchery produced urchins behave as wild individuals when exposed to the water-borne chemical signal from a potential predator
Long-Spined Urchin Research
Culturing Diadema to the early-benthic-stage remains highly problematic
We have a long way to go
Can we successfully translocate wild urchins onto restoration sites?
Long-Spined Urchin Research Does the degraded condition of the offshore reef bank provide sufficient habitat to support an ecologically functional population of Diadema?
Long-Spined Urchin Research Can artificial habitat increase survival rates?
Long-Spined Urchin Research Can artificial habitat increase survival rates?
Long-Spined Urchin Research Can artificial habitat increase survival rates?
Long-Spined Urchin Research Can artificial habitat increase survival rates?
Long-Spined Urchin Research Successful re-
establishment of long-spined urchins on highly degraded reefs will require habitat enhancement
Examine Staghorn coral/Diadema interaction
Herbivory ‒ Long-Spined Sea Urchin Research
Other Coral Reef Ecosystem Restoration Research
Predator/Prey Dynamics – Corallivorous gastropods & a potential predator
Impacts of snail predation upon both outplanted corals used in restoration and remnant wild colonies can be profound
Snail Predator Prey/Dynamics
Snail Predator Prey/Dynamics
We are investigating the predator/prey dynamics of these corallivores and a predatory snail, Thais deltoidea
Snail Predator Prey/Dynamics T. deltoidea readily
prey on corallivorous snails in the laboratory Is this trophodynamic
ecologically relevant?
‒ Prey preference ‒ Size-specific prey
selectivity ‒ Habitat mediated predator-
prey encounter rates
Snail Predator Prey/Dynamics Evaluating long-term
dataset of intensive benthic surveys conducted along the Florida Keys
Inform restoration activities by identifying potential areas where this trophodynamic may mitigate coral predation
Photo courtesy of Dirk Peterson
Our vision is to conduct progressively more complex restoration ecology research to guide resource managers in the development of an effective and holistic coral reef restoration strategy
Coral Reef Ecosystem Restoration Ecology Program
Photo courtesy of Jiangang Luo
Questions?