1
|
Skinner C, Bozec YM, Matthews SA, Williamson DH, Beeden R, Mumby PJ. Advancing projections of crown-of-thorns starfish to support management interventions. THE SCIENCE OF THE TOTAL ENVIRONMENT 2024; 950:175282. [PMID: 39111433 DOI: 10.1016/j.scitotenv.2024.175282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/10/2024] [Revised: 07/18/2024] [Accepted: 08/02/2024] [Indexed: 08/10/2024]
Abstract
Outbreaks of corallivorous Crown of Thorns Starfish (Acanthaster spp.; CoTS) cause substantial coral mortality throughout the Indo-Pacific, particularly on the Great Barrier Reef (GBR). Refining CoTS population density modelling and understanding the disparities between real-world observations and model predictions is crucial for developing effective control strategies. Using a spatially explicit ecosystem model of the GBR, we compared CoTS density model predictions to observations and incorporated a new zone-specific mortality rate to account for differences in predation of CoTS between fished and protected reefs. We found high congruence between predictions and observations: ∼81 % of categorical reef level CoTS densities matched or only differed by one category. However, underpredictions increased with higher observed densities. Zone-specific CoTS mortality reduced severe underpredictions from 7.1 % to 5.6 %, which is critical for managers as underpredictions indicate missing outbreaks where targeted culling is necessary, but also lead to underestimated coral loss attributed to CoTS outbreaks. Reef protection status affected prediction accuracy, highlighting the importance of further research on in situ CoTS mortality rates. The location of a reef inside or outside the "initiation box", a speculative area of primary outbreaks (i.e., initial abrupt population increases) on the GBR, also influenced accuracy, with exact predictions more likely outside. Accurately modelling initiation box dynamics is challenging due to limited empirical data on CoTS outbreaks, highlighting the need for focussed research on outbreak dynamics to enhance predictive accuracy. Spatial factors, such as region and shelf position, contributed to the variance between observations and predictions, underscoring the importance of the spatial-temporal context of each observation. Observations of CoTS can help refine model predictions, guide targeted control measures, and contribute to effective ecosystem management for the long-term resilience of the GBR and other reefs targeted by CoTS throughout the Indo-Pacific.
Collapse
Affiliation(s)
- Christina Skinner
- School of the Environment, University of Queensland, St Lucia 4072, QLD, Australia.
| | - Yves-Marie Bozec
- School of the Environment, University of Queensland, St Lucia 4072, QLD, Australia
| | - Samuel A Matthews
- Great Barrier Reef Marine Park Authority, Townsville 4810, QLD, Australia
| | - David H Williamson
- Great Barrier Reef Marine Park Authority, Townsville 4810, QLD, Australia
| | - Roger Beeden
- Great Barrier Reef Marine Park Authority, Townsville 4810, QLD, Australia
| | - Peter J Mumby
- School of the Environment, University of Queensland, St Lucia 4072, QLD, Australia
| |
Collapse
|
2
|
Desbiens AA, Roff G, Robbins WD, Taylor BM, Castro-Sanguino C, Dempsey A, Mumby PJ. Revisiting the paradigm of shark-driven trophic cascades in coral reef ecosystems. Ecology 2021; 102:e03303. [PMID: 33565624 DOI: 10.1002/ecy.3303] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 11/19/2020] [Accepted: 12/06/2020] [Indexed: 01/17/2023]
Abstract
Global overfishing of higher-level predators has caused cascading effects to lower trophic levels in many marine ecosystems. On coral reefs, which support highly diverse food webs, the degree to which top-down trophic cascades can occur remains equivocal. Using extensive survey data from coral reefs across the relatively unfished northern Great Barrier Reef (nGBR), we quantified the role of reef sharks in structuring coral reef fish assemblages. Using a structural equation modeling (SEM) approach, we explored the interactions between shark abundance and teleost mesopredator and prey functional group density and biomass, while explicitly accounting for the potentially confounding influence of environmental variation across sites. Although a fourfold difference in reef shark density was observed across our survey sites, this had no impact on either the density or biomass of teleost mesopredators or prey, providing evidence for a lack of trophic cascading across nGBR systems. Instead, many functional groups, including sharks, responded positively to environmental drivers. We found reef sharks to be positively associated with habitat complexity. In turn, physical processes such as wave exposure and current velocity were both correlated well with multiple functional groups, reflecting how changes to energetic conditions and food availability, or modification of habitat affect fish distribution. The diversity of species within coral reef food webs and their associations with bottom-up drivers likely buffers against trophic cascading across GBR functional guilds when reef shark assemblages are depleted, as has been demonstrated in other complex ecosystems.
Collapse
Affiliation(s)
- Amelia A Desbiens
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - George Roff
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - William D Robbins
- Wildlife Marine, Perth, Western Australia, Australia.,Department of Environment and Agriculture, Curtin University, Perth, Western Australia, Australia.,School of Life Sciences, University of Technology Sydney, Sydney, New South Wales, Australia.,Marine Science Program, Department of Biodiversity, Conservation and Attractions, Perth, Western Australia, Australia
| | - Brett M Taylor
- The Australian Institute of Marine Science, Crawley, Western Australia, Australia
| | - Carolina Castro-Sanguino
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| | - Alexandra Dempsey
- Khaled bin Sultan Living Oceans Foundation, Annapolis, Maryland, USA
| | - Peter J Mumby
- Marine Spatial Ecology Lab, School of Biological Sciences & Australian Research Council Centre of Excellence for Coral Reef Studies, The University of Queensland, Brisbane, Queensland, Australia
| |
Collapse
|
3
|
|
4
|
Relative efficacy of three approaches to mitigate Crown-of-Thorns Starfish outbreaks on Australia's Great Barrier Reef. Sci Rep 2020; 10:12594. [PMID: 32724152 PMCID: PMC7387460 DOI: 10.1038/s41598-020-69466-1] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2020] [Accepted: 07/13/2020] [Indexed: 11/18/2022] Open
Abstract
Population outbreaks of Crown-of-Thorns Starfish (COTS; Acanthaster spp.) are a major contributor to loss of hard coral throughout the Indo-Pacific. On Australia’s Great Barrier Reef (GBR), management interventions have evolved over four COTS outbreaks to include: (1) manual COTS control, (2) Marine Protected Area (MPA) zoning, and, (3) water quality improvement. Here we evaluate the contribution of these three approaches to managing population outbreaks of COTS to minimize coral loss. Strategic manual control at sites reduced COTS numbers, including larger, more fecund and damaging individuals. Sustained reduction in COTS densities and improvements in hard coral cover at a site were achieved through repeated control visits. MPAs influenced initial COTS densities but only marginally influenced final hard coral cover following COTS control. Water quality improvement programs have achieved only marginal reductions in river nutrient loads delivered to the GBR and the study region. This, a subsequent COTS outbreak, and declining coral cover across the region suggest their contributions are negligible. These findings support manual control as the most direct, and only effective, means of reducing COTS densities and improving hard coral cover currently available at a site. We provide recommendations for improving control program effectiveness with application to supporting reef resilience across the Indo-Pacific.
Collapse
|
5
|
Thiault L, Weekers D, Curnock M, Marshall N, Pert PL, Beeden R, Dyer M, Claudet J. Predicting poaching risk in marine protected areas for improved patrol efficiency. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2020; 254:109808. [PMID: 31739093 DOI: 10.1016/j.jenvman.2019.109808] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Revised: 10/25/2019] [Accepted: 10/28/2019] [Indexed: 05/05/2023]
Abstract
Marine Protected Areas (MPAs) are effective resource management and conservation measures, but their success is often hindered by non-compliant activities such as poaching. Understanding the risk factors and spatial patterns of poaching is therefore crucial for efficient law enforcement. Here, we conducted explanatory and predictive modelling of poaching from recreational fishers within no-take zones of Australia's Great Barrier Reef Marine Park (GBRMP) using Boosted Regression Trees (BRT). Combining patrol effort data, observed distribution of reported incidents, and spatially-explicit environmental and human risk factors, we modeled the occurrence probability of poaching incidents and mapped poaching risk at fine-scale. Our results: (i) show that fishing attractiveness, accessibility and fishing capacity play a major role in shaping the spatial patterns of poaching; (ii) revealed key interactions among these factors as well as tipping points beyond which poaching risk increased or decreased markedly; and (iii) highlight gaps in patrol effort that could be filled for improved resource allocation. The approach developed through this study provide a novel way to quantify the relative influence of multiple interacting factors in shaping poaching risk, and hold promises for replication across a broad range of marine or terrestrial settings.
Collapse
Affiliation(s)
- Lauric Thiault
- National Center for Scientific Research, PSL Université Paris, CRIOBE, USR 3278, CNRS-EPHE-UPVD, Maison des Océans, 195 Rue Saint-Jacques, 75005, Paris, France; Laboratoire D'Excellence CORAIL, Moorea, French Polynesia.
| | - Damian Weekers
- School of Social Science, University of Queensland, Michie Building, St Lucia, QLD, 4072, Australia; Great Barrier Reef Marine Park Authority, Townsville, QLD, 4810, Australia
| | - Matt Curnock
- CSIRO Land and Water, James Cook University, Townsville, QLD, 4811, Australia
| | - Nadine Marshall
- CSIRO Land and Water, James Cook University, Townsville, QLD, 4811, Australia
| | - Petina L Pert
- CSIRO Land and Water, James Cook University, Townsville, QLD, 4811, Australia
| | - Roger Beeden
- Great Barrier Reef Marine Park Authority, Townsville, QLD, 4810, Australia
| | - Michelle Dyer
- Great Barrier Reef Marine Park Authority, Townsville, QLD, 4810, Australia
| | - Joachim Claudet
- National Center for Scientific Research, PSL Université Paris, CRIOBE, USR 3278, CNRS-EPHE-UPVD, Maison des Océans, 195 Rue Saint-Jacques, 75005, Paris, France; Laboratoire D'Excellence CORAIL, Moorea, French Polynesia
| |
Collapse
|
6
|
Madin EMP, Precoda K, Harborne AR, Atwood TB, Roelfsema CM, Luiz OJ. Multi-Trophic Species Interactions Shape Seascape-Scale Coral Reef Vegetation Patterns. Front Ecol Evol 2019. [DOI: 10.3389/fevo.2019.00102] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
|
7
|
Lam VYY, Chaloupka M, Thompson A, Doropoulos C, Mumby PJ. Acute drivers influence recent inshore Great Barrier Reef dynamics. Proc Biol Sci 2018; 285:rspb.2018.2063. [PMID: 30404884 DOI: 10.1098/rspb.2018.2063] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2018] [Accepted: 10/12/2018] [Indexed: 11/12/2022] Open
Abstract
Understanding the dynamics of habitat-forming organisms is fundamental to managing natural ecosystems. Most studies of coral reef dynamics have focused on clear-water systems though corals inhabit many turbid regions. Here, we illustrate the key drivers of an inshore coral reef ecosystem using 10 years of biological, environmental, and disturbance data. Tropical cyclones, crown-of-thorns starfish, and coral bleaching are recognized as the major drivers of coral loss at mid- and offshore reefs along the Great Barrier Reef (GBR). In comparison, little is known about what drives temporal trends at inshore reefs closer to major anthropogenic stress. We assessed coral cover dynamics using state-space models within six major inshore GBR catchments. An overall decline was detected in nearly half (46%) of the 15 reefs at two depths (30 sites), while the rest exhibited fluctuating (23%), static (17%), or positive (13%) trends. Inshore reefs responded similarly to their offshore counterparts, where contemporary trends were predominantly influenced by acute disturbance events. Storms emerged as the major driver affecting the inshore GBR, with the effects of other drivers such as disease, juvenile coral density, and macroalgal and turf per cent cover varying from one catchment to another. Flooding was also associated with negative trends in live coral cover in two southern catchments, but the mechanism remains unclear as it is not reflected in available metrics of water quality and may act through indirect pathways.
Collapse
Affiliation(s)
- Vivian Y Y Lam
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, St. Lucia, Queensland, Australia .,Australian Research Council Centre of Excellence for Coral Reef Studies, St. Lucia, Queensland, Australia
| | - Milani Chaloupka
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, St. Lucia, Queensland, Australia.,Ecological Modelling Services Pty Ltd, The University of Queensland, Queensland, Australia
| | - Angus Thompson
- Australian Institute of Marine Science, Townsville, Queensland, Australia
| | - Christopher Doropoulos
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, St. Lucia, Queensland, Australia.,CSIRO Oceans and Atmosphere, St. Lucia, Queensland, Australia
| | - Peter J Mumby
- Marine Spatial Ecology Lab, School of Biological Sciences, The University of Queensland, St. Lucia, Queensland, Australia .,Australian Research Council Centre of Excellence for Coral Reef Studies, St. Lucia, Queensland, Australia
| |
Collapse
|