Response of Reef-Fish Habitat
Specialists to Ramicrusta sp. Algal
Overgrowth of Fire Coral
AnnaRose Adams
Department of BioResource Research
Oregon State University
Habitat association
http://www.reefteach.com.au
http://www.ncwildlife.org
http://birdssurfblog.com
Habitat specialization
Generalists
http://www.vutrax.co.uk/
https://ig08pq.bay.livefilestore.com
Specialists
http://makarl.wordpress.com
http://lh5.ggpht.com
Habitat Specialists at Risk
Munday 2004
Coral as Habitat
http://c.photoshelter.com
http://www.coralreefphotos.com
http://media-cdn.tripadvisor.com
Algal Overgrowth
http://www.thewe.cc
http://www.ok4me2.net
http://coralmorphologic.com/
Conditions
change
Ramicrusta
http://www.inhabitat.com/
• Crustose alga
• Recently described species
• Observed in Bonaire and
Jamaica
• Overgrows coral
How does Ramicrusta overgrowth
of coral affect fish who are
habitat specialists?
Study Coral: Millepora complanata
http://www.indigomoon.us/
http://coralpedia.bio.warwick.ac.uk
http://www.orafarm.com/
http://www.seattleyates.com
fire coral
Predictions
Normal
Overgrown
http://www.infobonaire.com
http://marketinginthemaking.wordpress.com
Coral Measurements
Volume dimensions
Signs of distress
Percent overgrowth
Fish Counts
40 cm criteria
Number of fish
40
Family of fish
Percent Overgrowth
0%
1 – 25%
26 – 50%
51 – 75%
Increasing Ramicrusta overgrowth
76 – 100%
Fish Abundance and Diversity
Abundance: number of fish
Richness: number of families
Evenness: equality of representation among families
Composite Diversity: combined richness and evenness
http://www.bluezooaquatics.com/
http://farm3.static.flickr.com
http://sealandphotography.com http://saltwater.tropicalfishandaquariums.com
Trends in Overgrowth
Number of coral heads
observed
60
88%
50
40
30
20
10
0
0%
1 - 25%
26 - 50%
51 - 75%
Algal Overgrowth Category
76 - 100%
Fish Abundance
p=0.01
Greater mean number of
fish at high levels of
overgrowth
Suggests trend opposite
to predictions
Difference of 1 fish not
ecologically significant
Fish Diversity
Higher mean values with
increasing overgrowth
Statistically nonsignificant
Structural Complexity
http://sjue.com/
Complexity increases
with coral size
http://img.freebase.com
Influence of Coral Volume
p<0.0001
Mean coral size
significantly smaller at
low overgrowth
Differences in fish
communities influenced
by coral size
Large values
could be a
product of bigger
coral heads
Influence of Ramicrusta
Potential to have little
effect on coral complexity
Study examined recent
Ramicrusta overgrowth
Fully overgrown corals die
and are eroded
Over time Ramicrusta could
impact coral structure
Conclusions
Ramicrusta is changing the sea floor
composition of Lac Bay, Bonaire.
Differences in coral volume may have
influenced fish abundance and diversity.
Fish used fire coral regardless of presence of
recent Ramicrusta overgrowth.
Acknowledgments
Oregon State University ER Jackman Internship Support Program
Dr. Rita Peachey and staff
CIEE Bonaire Research Station
Tom Stabler
Goucher College
Dr. Mark Hixon, Dr. Selina Heppell and Dr. Scott Heppell
Dept. Zoology and Dept. Fish and Wildlife, Oregon State University
Questions?
References
Munday PL (2004) Habitat loss, resource specialization, and extinction
on coral reefs. Global Change Biol 10: 1642–1647
Fish Families Observed
Gobiidae - Gobies
Labridae - Wrasse
Blennidae – Blennies
Grammatidae – Basslets
Serranidae – Grouper/Grasby/Creolefish
Pomacanthidae – Damselfish
Lutjanidae – Snapper
Balistidae – Triggerfish
Scaridae – Parrotfish
Acanthuridae – Surgeonfishes and Tangs
Equations
Composite Diversity: H’ = ∑ pi ln(pi)
pi = proportion of individuals observed within
each family
Evenness: E = H’/ ln(S)
S = family richness
Data Analysis
• Anderson-Darling Normality tests (failed)
• Kruskal-Wallis tests (α = 0.05)
• Mann-Whitney U-tests (α = 0.05)
• Linear regression analysis