UNDERSTANDING THE ROLE OF HERBIVORY AND PREDATOR/PREY INTERACTIONS TO GUIDE THE DEVELOPMENT OF A COMPREHENSIVE CORAL REEF RESTORATION STRATEGY

Transcription

1 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

2 From: Gardner et al Images: Gene Shinn. Tropical Treasures - South Florida Marine Environments

3 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

4 What can we do? Reduce land-based sources of impact Reduce direct impacts from human usage Manage to maintain biodiversity Establish Marine Protected Areas

5 But is this enough? Increasing acceptance that restoring Florida s coral reef ecosystem will require active restoration efforts CRF/Tim Grolimund

6 Coral Restoration Restoring the physical reef structure is the necessary first step toward coral reef ecosystem restoration CRF/Tim Grolimund

7 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

8 Other Coral Reef Ecosystem Restoration Research Herbivory Long-Spined Sea Urchin Research Predator/Prey Dynamics Corallivorous gastropods & a potential predator

9 Other Coral Reef Ecosystem Restoration Research Herbivory Long-Spined Sea Urchin Research Predator/Prey Dynamics Corallivorous gastropods & a potential predator

10 Long-Spined Urchin Research Importance of the species Diadema antillarum Keystone coral reef herbivore Caribbean-wide mortality event in 1980s Recovery identified as necessary to improve health of coral reef ecosystem

11 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?

12 D antillarum typically exhibit diurnal sheltering behavior Sheltering Behavior

13 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

14 Behavior - Shelter Usage wild & hatchery in separate mesocosms percentage in shelter (+ 1 se) P = NS wild hatchery Day Night

15 Behavior - Shelter Usage wild & hatchery mixed in same mesocosm percentage in shelter (+ 1 se) P = P = wild hatchery Day Night

16 Behavior - Shelter Usage Next hatchery-bred cohort Shelter provided until transported to FWC lab ~ 5 mm test diameter

17 Behavior - Shelter Usage Shoebox Experiments Hatchery-bred urchins given appropriately scaled light/dark choice

18 Behavior - Shelter Usage Shoebox Experiments 1.2 Hatchery-bred urchins given appropriately scaled light/dark choice Observed diurnal differences in sheltering behavior Mean (+- 1 SE) % in Shelter N = /01/11 06/02/11 06/03/11 06/04/11 06/05/11 DATE Day Night

19 Behavior - Shelter Usage NS Shoebox - Day NS Shoebox - Night

20 Long-Spined Urchin Research Chemotactic responses to predation threat Wild urchins will avoid the waterborne chemical signal of a predator From Kintzing 2010

21 Chemotactic Responses to Predation Threat Approach modeled after Kintzing (2010) Tracked overall movement of hatchery-bred urchins in response to lobster chemical cue

22 Chemotactic Responses to Predation Threat Hatchery-bred responded similarly to wild urchins as reported by Kintzing (2010)

23 Sheltering Behavior Summary 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

24 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?

25 Long-Spined Urchin Research Does the degraded condition of the offshore reef bank provide sufficient habitat to support an ecologically functional population of Diadema?

26 Long-Spined Urchin Research Can artificial habitat increase survival rates?

27 Long-Spined Urchin Research Can artificial habitat increase survival rates?

28 Long-Spined Urchin Research Can artificial habitat increase survival rates?

29 Long-Spined Urchin Research Can artificial habitat increase survival rates?

30 Long-Spined Urchin Research Successful reestablishment of longspined urchins on highly degraded reefs will require habitat enhancement Examine Staghorn coral/diadema interaction

31 Other Coral Reef Ecosystem Restoration Research Herbivory Long-Spined Sea Urchin Research Predator/Prey Dynamics Corallivorous gastropods & a potential predator

32 Snail Predator Prey/Dynamics Impacts of snail predation upon both outplanted corals used in restoration and remnant wild colonies can be profound

33 Snail Predator Prey/Dynamics We are investigating the predator/prey dynamics of these corallivores and a predatory snail, Thais deltoidea

34 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 predatorprey encounter rates

35 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

36 Coral Reef Ecosystem Restoration Ecology Program 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 Photo courtesy of Dirk Peterson

37 Questions? Photo courtesy of Jiangang Luo