Transcript Shelley - York College of Pennsylvania

Species composition and percent coverage of stony corals in
three Caribbean reefs in St Vincent and the Grenadines
Melissa Shelley
Dept. of Biological Sciences, York College of Pennsylvania
Percent Coral Coverage
Site 1: Horseshoe
Reef, Tobago Cays
•Fringing barrier reef
located within Tobago
Cays Marine Park
(established 1998)
50
Site 1
Site 2
Site 3
40
30
20
10
ft
ft
20
60
Site 2: Orca Point,
St. Vincent
Depth (ft)
•The data was transformed with an arc sin square root (x)
• No significant differences were found in percent coverage
over the three sites using a two-way ANOVA statistical test
and a Bonferroni post-test
•No significant differences were found between depths at
each site
•The bars on this graph represent the mean and the error
bars represent the standard error of the mean (SEM)
Site 3: Bat Cave, St.
Vincent
•Fringing reef located
near island shore and
river in the Wacumet
Valley
2.0
Materials
0.5
ft
20
ft
Depth (ft)
•No significant differences were found in species diversity
over the three sites
•No significant differences between depths at each site
1.5
Site 1
Site 2
Site 3
1.0
0.5
ft
60
Depth (ft)
•Hughes, T. P. and Connell, J. H.. 1999. Multiple stressors on coral reefs:
a long-term perspective. Limnology and Oceanography. 44:932-940.
•No significant differences were found in species evenness
over the three sites
•No significant differences between depths at each site
b
b
4
a
a,b
a
a
Site 1
Site 2
Site 3
2
60
20
ft
ft
0
Repeat procedure five more
times at same depth
Depth (ft)
Species Richness
Repeat entire
procedure at
depth of 20 ft
•Continue surveying reef structures over a
longer period to determine the relative
importance of large-scale natural disturbances
and smaller-scale human disturbances.
• Buddemeier, R.W.; Kleypas J.A.; Aronson, R. B. 2004. Coral reefs and
global climate change: potential contributions of climate change to
stresses on coral reef ecosystems. Pew Center on Global Climate Change.
0.0
6
Count number of chain links
covering each species of stony
coral
*excluding dead or bleached
corals*
•Survey algal abundance and coral abundance
to determine correlation between algal and coral
communities.
Work Cited
Species Evenness
Set end of chain down and lay
chain across coral
•Site 1: Site 1 was formed into a marine park
in 1998. The short time span that has
elapsed may not have allowed corals to fully
recover from previous natural and human
disturbances.
•Future studies that might be conducted might
include the following:
Species Diversity
Swim five kick strokes in random
direction along reef with eyes
closed
•Few significant differences were found
between sites. The data did not clearly
establish a relationship between the believed
levels of human disturbances of the three sites
and the species composition or percent
coverage of stony corals.
•This suggests that Site 1 may have been
more impacted than previously expected.
ft
At Depth: 60
ft
•No change in coral diversity, evenness, and
percent coverage was found.
•Overall there were small differences in the three
sites for species richness.
•Site 2 had greater species richness than either
site 1 or site 3 at 60 ft
•Site 1 had the lower species richness at 20 ft
than Site 3.
•Corals take an estimated 15-20 years to
recover from disturbances (Hughes and
Connell 1999).
1.0
0.0
Procedure
Data collected August 2007
1.5
60
•46’ Catamaran
•Dive Gear
•Two teams of two divers
•6 Transect lines (210 links at 2cm per link)
•Coral Identification Chart (Humann and
Deloach 2002)
Site 1
Site 2
Site 3
20
Photo courtesy:
http://www.divestvincent.com/JPEGS/07BatCave432.jpg
Image courtesy: http://www.grenadinesailing.com/images/map.jpg
Discussion
Percent Coral Coverage
•Fringing reef located
near island shore
This study observed the species composition and
percent coverage of stony corals at three reefs in
Caribbean located near the islands of St. Vincent
and the Grenadines. These reefs differ in their
exposure human disturbances. The first site being
a part of the Tobago Cays Marine Park, created in
1998, is being considered as the least impacted by
humans. The second site, considered moderately
impacted, is located off the coast of the populated
island of St Vincent. The third site is considered
the most heavily impacted and is located near the
mouth of a river from the Wacumet Valley in St.
Vincent.
Ho: There will be no difference in coral
diversity, evenness, richness or percent
coral coverage between the three sites or
between the two depths
Results
0
Diversity (H)
Intermediate Disturbance Hypothesis
•Definition: Both high and low levels of
disturbance will lead to reduced diversity in
communities, where maximum species diversity will
be found in intermediate levels of diversity (Molles
2002).
•Low Disturbance: species diversity limited by
successful competitors.
•High Disturbance: The community will
consist only of those species that can colonize
and complete their life cycles between
disturbances
Caribbean coral reefs have suffered massive
disturbances that have affected coral species
diversity (Buddemeier et al 2004).
•Natural Disturbances
•Hurricanes, El Niño, climate changes
•Caribbean-wide bleaching caused by El Niño
in 1998
•Diseases
•Mass Diadema antillarum die-off in1983-84
•Allowed algae and phytoplankton to bloom
and overgrow the coral
•Mass Elkhorn (Acropora palmeta) and
Staghorn (A. cervicornis) coral die-off due to
White Band disease
•Major reef builders in Caribbean
•Disease introduced in 1972 and has
changed coral community structures
•Human Disturbances
•Sedimentation and nutrient loading from
freshwater runoff
•Direct destruction of reefs and coastal habitat
modifications
•Overfishing
Results
Sites
Evenness
Introduction
Number of Species
Scanned image courtesy Molles 2002
•No significant differences were found between depths at
each site
•Site 2 was significantly different from Site 1 and Site 3 at
60 ft
•Site 3 was significantly different from Site 1 at 20 ft
•Humann P. and Deloach, N.. 2002. Reef Coral Identification: Florida,
Caribbean, Bahamas. New World Publications.
•Molles, M. C.. 2002. Ecology: Concepts and Applications. McGraw Hill
Publication. Second edition.
Acknowledgments
I’d like to thank Jason Buchheim and Odyssey Expeditions
for allowing me to perform this research while participating
in their program. I’d also like to thank Jason Buchheim,
Jeni Kovac, and Devon Crippen for helping collect the data
needed. I am also thankful for all the advice and guidance
provided by Dr. Jessica Nolan throughout the entire thesis
process.