Effects of a Marine Reserve on Reef Fish Species

1
Effects of a Marine Reserve on Coral Reef Fish
Species
By Robert Lamb PI Mark Hixon OSU Zoology
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Importance of Marine Reserves

• Fishing can impact the structure of ecosystems
• Fully protected marine reserves prohibit
  extractive activities

3
Changes to Overall Trophic Structure?

• -Basic food web

4
Changes to Overall Trophic Structure?

• Removal of large top-level predators

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Changes to Overall Trophic Structure?

• Removal of large top-level predators
• Trophic Cascade

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Changes to Overall Trophic Structure?

• Removal of large top-level predators
• Trophic Cascade
• Shift in proportional abundance of trophic levels

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Study Sites
8

• Perry Institute for Marine Science

Lee Stocking Island, Bahamas
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Exuma Cays Land and Sea Park
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Developing the Research Project

• Is the fish community structure on reefs inside
  the Exuma Cays Land and Sea Park different from
  those found outside the reserve?

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Research Sites

• 5 protected sites within the marine reserve, 5
  unprotected sites outside of the reserve
• Protected and unprotected sites were paired by
  habitat similarity

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Methods

• Underwater surveys performed at each site using
  SCUBA
• Counts recorded on waterproof plastic slates

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Methods

• 25 x 5 meter transects
• Individual fish identified to species
• Lengths were visually estimated

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Methods

• Randomized transect placement
• Minimized effects of observers presence
• Fish of every trophic level were counted and
  measured

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Predictions
Unprotected vs. Protected ?????
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Species Richness
50
Number of Species per Transect (mean 1SE)
40
Protected Unprotected
30
20
n 6 transects per site
10
0
Site Pairings
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Lengths of Common Large Carnivores
160
140
120
100
Protected
80
Unprotected
Average Size (cm) 1SE
60
40
20
0
Bar Jack
Schoolmaster
Great Barracuda
Nassau Grouper
Saucereye Porgy
Graysby Grouper
Yellowtail Snapper
Species
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Density of Common Large Carnivores
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Fish Abundance by Trophic Level (individuals gt
30cm)
Protected
Unprotected
25
4
37
36
29
24
11
20
Fish Abundance by Trophic Level (individuals gt
30cm)
Protected
Unprotected
25
4
37
36
29
24
11
21
Other large piscivorous predators were only
recorded inside of the marine reserve
Black Grouper, Mycteroperca bonaci Max 133
cm
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Other large piscivorous predators were only
recorded inside of the marine reserve
Black Grouper, Mycteroperca bonaci Max 133
cm
Tiger Grouper, Mycteroperca tigris Max 100 cm
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Other large piscivorous predators were only
recorded inside of the marine reserve
Black Grouper, Mycteroperca bonaci Max 133
cm
Tiger Grouper, Mycteroperca tigris Max 100 cm
Reef Shark, Carcharhinus perezi Max 295 cm
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Conclusions

• Top-level predators are larger, more abundant
  within marine reserve
• Trophic structure of reef fish community is
  somewhat different
• Species richness is not different

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Many thanks to

• Mark Hixon, Darren Johnson, Mark Albins, Tim
  Pusack, Chris Stallings, Flower Moye, Brenda
  Gadd, URISC and HHMI Scholarship Programs.
• Photos Provided By Mark Albins, Darren Johnson,
  Tim Pusack, Flower Moye, and Adam Harrison.