spatial ecology of reef fishes justin welsh and david bellwood
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Spatial Ecology of Reef Fishes
Justin Welsh and David Bellwood
Roles on reefs: Herbivory
Introduction
•Transport sediment
•Maintain algal turfs
•Remove macroalgae
•Overall, support resilience
Importance of resilience
Introduction
?
Who and what... We think we know. But where and why?
Introduction
Introduction
Haremic versus Schooling
What is the spatial ecology of roving herbivores and is there an influence of social systems?
Introduction
Chlorurus microrhinos
•Haremic
•Roving herbivore
•Active telemetry
Case study: the parrotfishes
Scarus rivulatus
•Schooling
•Roving herbivore
•Passive telemetry
•Algal removal
•Leave deep, long-lasting grazing scars
•Haremic
Introduction
Chlorurus microrhinos
Objectives:
•Quantify home range size
•Determine the influence of physical factors
•Implications for ecosystem role
Introduction
Study site: Orpheus Island, Pioneer Bay
Methods
Capture
•Barrier netting
Methods
Capture
Tagging
•Anesthetic
MS-222
•Tag
(V9T-2H, Vemco)
•Suture
Methods
Tracking
•Tracking from Kayak
for 3 - 5 days(Meyer and Holland 2005)
•Receiver
(VR100, Vemco)
•Directional hydrophone
(VH1110, Vemco)
Methods
Home range: 8,100 m2
Core area: 1,690 m2
Results
Welsh and Bellwood 2012, Coral Reefs Vol: 31
Core vs non-core: Physical characteristics:
Results
Results:
*
*
Core area Non-core area *
*
•Core areas centered on topographic complexity
•Limited mobility in haremic parrotfish
•What about schooling species?
Summary
Herbivores
• So far, highly site attached
• Social species?
• e.g. schooling?
Introduction
Scarus rivulatus• Highly abundant
• Important herbivores
• Schooling species
• Roving herbivore?
Introduction
Introduction
Objectives:
•Evaluate the foraging range of S. rivulatus
•Understand the foraging range of their schools
Passive acoustic telemetry
Introduction
Heupel et al 2006
• VR2W receivers
• V9 transmitters
• 60 m detection rangeWelsh et al. 2012, Coral Reefs
Orpheus island array
Methods
Capture
• 3 schools captured using barrier nets
Methods
Tagging
• Same tagging procedure as per active tracking
• Monitor individuals for 7 months
Spatial data analysis
• Maximum potential foraging range
Chapter 2
>5%>5% >5%>5%
<5%<5%
>5%>5% >5%>5%
<5%<5%
Spatial range
Results
• Average area occupied: 0.244 km2
Welsh and Bellwood 2012, Coral Reefs
Results
• Average area occupied by the school: 0.238 km2
Spatial range
Conclusion
• Site attached
• Facultative schooling
• Limited school fidelity
Conclusion
Introduction
Chlorurus microrhinos
•Haremic
•Site attached
Scarus rivulatus
•Schooling
•Site attached
Herbivores from a different perspective:Regardless of social system, functional role occurs
on small spatial scales
Credits
David Bellwood, Roberta Bonaldo, Simon Brandl, Rebecca Fox. Chris Goatley, Andy Hoey, Jess Hopf, Charlotte Johansson, Michael Kramer, Susannah Leahy, Carine Lefèvre, Jenn Tanner, OIRS and LIRS staff and Vemco.Photos by Joao Paulo KrajewskiFunding provided by: ARC center of excellent for coral reef studies, Australian museum, James Cook University
Schooling and feeding
• Feeding observations:
‣ 160 individuals, 1 min each, 4 times of the day, 2 sites
Results
Significance of schooling
Results