A Comparison of Damselfish Densities on Live Staghorn
Coral (Acropora cervicornis) and Coral Rubble in
Dry Tortugas National Park
Allison A. Wilkes, Melissa M. Cook, Anthony L. DiGirolamo, John Eme, Jeff M. Grim, Bernadette C. Hohmann, Sara L. Conner, Cheryl J. McGill, Christopher M. Pomory, and Wayne A. Bennett
Southeastern Naturalist, Volume 7, Number 3 (2008): 483–492
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2008 SOUTHEASTERN NATURALIST 7(3):483–492
A Comparison of Damselfish Densities on Live Staghorn
Coral (Acropora cervicornis) and Coral Rubble in
Dry Tortugas National Park
Allison A. Wilkes1,*, Melissa M. Cook1, Anthony L. DiGirolamo2,
John Eme3, Jeff M. Grim4, Bernadette C. Hohmann5, Sara L. Conner1,
Cheryl J. McGill6, Christopher M. Pomory1, and Wayne A. Bennett1
Abstract - Over the past 30 years, cold events and disease have reduced much
of the live Acropora cervicornis (Staghorn Coral) in Dry Tortugas National Park
(DTNP), FL to fields of coral rubble. It is unclear how the resulting loss of threedimensional
reef structure has affected density and distribution of reef-dependent
damselfishes. We compared densities of Stegastes adustus (Dusky Damselfish),
Stegastes leucostictus (Beaugregory Damselfish), Microspathodon chrysurus (Yellowtail
Damselfish), Stegastes planifrons (Three-spot Damselfish) and Stegastes
variabilis (Cocoa Damselfish) inhabiting DTNP’s last live Staghorn Coral formation
with densities from surrounding coral rubble. Live Staghorn Coral supported
a 65% higher damselfish density compared to coral rubble. Density of Dusky,
Cocoa, Beaugregory, Yellowtail and Three-spot Damselfish on coral rubble (0.11,
0.58, 0.74, 0.02, and 0.06 fish/m2, respectively) was less than that found on living
Staghorn Coral colonies (2.03, 0.45, 0.25, 0.50, and 0.96 fish/m2, respectively).
Dusky Damselfish dominated the live Staghorn Coral site, while Cocoa and Beaugregory
Damselfish dominated the coral rubble site. Juvenile density was ten times
greater on coral rubble than on live Staghorn Coral, whereas adults had highest
densities on live Staghorn Coral.
Approximately 113 km west of Key West, FL, the Dry Tortugas National
Park (DTNP) is the site of one of the most expansive and pristine coral reefs
in the Florida reef tract (Fig.1) and the continental United States. Although
extensive branching coral formations were reported within the DTNP area
from the early 1880s through the mid-1970s (Davis 1982), stands of branching
coral within the Park have been in decline for the past 30 years. A severe
cold front during the winter of 1976–77 destroyed nearly 96% of DTNP’s
Staghorn Coral within two meters of the surface (Bohnsack 1983), and
outbreaks of white band disease during the 1980s further degraded already
damaged reefs in the Florida reef track (Williams 1997) and throughout the
Caribbean (Aronson and Precht 2001, Vargus-Angel et al. 2003). While
cycles of natural destruction and rebuilding are typical on healthy reefs
1Department of Biology, University of West Florida, Pensacola, FL 32514. 2Florida
Fish and Wildlife, Jacksonville, FL 32221. 3University of California, Irvine, CA,
92627. 4Ohio University, Athens, GA 45701. 5Mote Marine Lab, Sarasota, FL 34236.
6US Environmental Protection Agency, Gulf Breeze, FL 32561. *Corresponding author
484 Southeastern Naturalist Vol.7, No. 3
(Davis 1982, Smith and Buddemeier 1992), cold events followed closely by
disease outbreaks have overtaxed the regenerative abilities of Staghorn Corals
in the Park (Davis 1982, Porter et al. 1982, Reaka-Kudlat et al. 1996).
Based on personal observation and using site locations provided by other
researchers and DTNP officials, our systematic search revealed that of the
Park’s once extensive living Staghorn Coral formation, only a single large
65-m2 remnant of Staghorn Coral remains (24°37'13"N, 82°52'10"W).
Whereas destructive effects of environmental disasters on reefs are
immediately noticeable, long-term repercussions of coral loss on reef-dependent
fishes are less obvious and often overlooked (Booth and Beretta
2002, Jaap 2001). Damselfishes (Family: Pomacentridae) are an important
component of the coral reef ichthyofauna. Commonly regarded as
keystone species, damselfishes directly influence reef ecology and diversity
(Hixon and Brostoff 1983, Williams 1980) and are considered good
indicators of reef assemblage health (Aronson and Precht 1997, Emery
1973, Lieske and Meyers 1999, Longley and Hilderbrand 1941). Shifts
from complex branching coral habitat to relatively uniform rubble have
almost certainly altered damselfish distribution and ecology in DTNP, but
it is unclear how and to what degree populations may have been affected.
Previous research has shown damselfish populations differ with substrate
complexity (Almany 2004, Holbrook et al. 2000, Lirman 1994, Nemeth
1998), coral cover (Clapp 2005, Sale 1972), competition (Jones 1987),
and community structure (Abrey 2005; Itzkowitz 1977, 1985). Life-history
studies have described damselfish habitat preferences (Myrberg 1971,
Wellington 1992, Williams 1979), but have not examined damselfish distribution
after preferred areas have been altered or destroyed. Likewise,
reports of damselfish distribution and density on Florida reefs are limited
Figure 1. Map of Dry Tortugas National Park showing live Staghorn Coral (Acropora
cervicornis) (S) and coral rubble (R) study sites within the Park.
2008 A.A. Wilkes et al. 485
(Emery 1973, Wallman et al. 2004) and have focused primarily on ecology
of damselfishes inhabiting low-energy patch-reef formations that were
largely unaffected by cold and disease.
Loss of branching coral habitat has been a chronic problem throughout
the Caribbean. A better understanding of reef fish distribution on rubble
fields will provide insights into aspects of reef ecology following disturbance.
Subsequently, we quantified adult and juvenile damselfish densities
and species assemblages on live Staghorn and adjacent coral rubble habitats
Materials and Methods
We determined damselfish densities on the largest remaining live Staghorn
Coral formation and a nearby coral rubble habitat within DTNP during
the first week of May 2004. Live Staghorn Coral and coral rubble study sites
were located at 24°37'13"N, 82°52'10"W near Garden Key. Coral rubble was
comprised of dead and broken Staghorn located approximately 30 m from
the live Staghorn patch. All sampling was conducted during daylight hours.
Damselfish densities were quantified on 20-m transect lines marked at 1-m
intervals and carefully placed on live Staghorn Coral and coral rubble areas
(1-2 m depth). Owing to unfavorable weather conditions, fewer transect were
sampled on rubble sites. Eight non-overlapping transects were sampled on
live Staghorn Coral, and four transects were sampled on coral rubble. Each
transect was distanced far enough apart to prevent fish territory overlapping.
Transects were sampled by four teams of two snorkelers on the surface
moving at a slow rate, not exceeding 1 m/min. Damselfish within one-half
meter of either side of the transect line were recorded. Using distinctive differences
in coloration pattern, relative body shape, and size characteristics
as described by Smith (2002), damselfish were identified to species and classified as either juvenile or adult. Data were categorized as: 1) total number
of damselfish regardless of species or life stage, 2) total number of adult and
juvenile fish regardless of species and within each species, and 3) total number
of each species regardless of life stage. Counts of the four snorkel teams
were averaged to produce a single value for each transect for each category.
Counts per transect were divided by total transect area and reported as fish/
Total damselfish density (all species and life stages combined) on live
Staghorn Coral and coral rubble was compared using one-way ANOVA on
ranked data. Total density was used for comparisons in order to compensate
for zeroes in individual species data. Comparisons of adult densities (all species
combined) between habitat types, as well as juvenile densities (all species
combined) between habitat types were made using one-way ANOVA
on ranked data. Comparisons of adult versus juvenile densities (all species
combined) within both habitat types were made using a blocked ANOVA on
ranked data with transects as blocks. Comparisons of densities by species of
damselfish (adults and juveniles combined) within both habitat types were
486 Southeastern Naturalist Vol.7, No. 3
made using a blocked ANOVA on ranked data. Tukey’s multiple comparison
procedure was used following significant ANOVA. Based on the number of
statistical tests performed using the same data set, α = 0.007 was used as
the significance level to adjust for multiplicity. Mean density of juvenile and
adult damselfish by species and by habitat type are reported, but were not
Damselfish densities differed markedly between live Staghorn Coral
and coral rubble sites. Total damselfish density was significantly higher,
approximately 65%, (one-way ANOVA: F1,10 = 20.43, P = 0.0011) on live
Staghorn Coral (mean = 4.18 ± 3.611 SE fish/m2) compared with coral
rubble (mean = 1.50 ± 1.155 SE fish/m2). Differences were also found in
damselfish density relative to life stage between and within the two habitat
sites. Adult damselfish density was significantly higher (one-way ANOVA:
F1,10 = 46.24, P < 0.0001) on live Staghorn Coral (mean = 4.13 ± 3.089 SE
fish/m2) compared with coral rubble (mean = 0.62 ± 0.327 SE fish/m2).
Conversely, juvenile damselfish density was significantly higher (one-way
ANOVA: F1,10 = 45, P < 0.0001) on coral rubble (mean = 0.88 ± 0.961 SE
fish/m2) compared with live Staghorn Coral (mean = 0.04 ± 0.135 SE fish/
m2). Adult damselfish density was significantly higher than juvenile damselfish
density on live Staghorn Coral (blocked ANOVA: F1,7 = 23.97, P =
0.0018), but no significant difference was found on coral rubble (blocked
ANOVA: F1,3 = 18, P = 0.024).
Species composition differed within the two habitat sites as well. On
live Staghorn Coral (Fig. 2A), the density of Stegastes adustus (Troschel)
(Dusky Damselfish) was significantly higher (blocked ANOVA: F4,28 = 8.32,
P = 0.0001) than Microspathodon chrysurus (Cuvier) (Yellowtail Damselfish),
S. leucostictus (Muller and Troschel) (Beaugregory Damselfish), S.
variabilis (Castelnau) (Cocoa Damselfish) and Stegastes planifrons (Curier)
(Three-spot Damselfish) (similar densities). On coral rubble (Fig. 2B), Beaugregory
and Cocoa Damselfish (similar densities) had significantly higher
densities (blocked ANOVA: F4,12 = 104.5, P < 0.0001) than Yellowtail,
Dusky, and Three-spot Damselfish (similar densities).
The pattern of species density by habitat and life stage was variable.
Juvenile density on live Staghorn Coral was highest for Beaugregory Damselfish and lowest for Cocoa Damselfish, but adult density was highest
for Dusky Damselfish and lowest for Beaugregory Damselfish (Table 1).
Juvenile density on coral rubble was highest for Beaugregory Damselfish
and lowest in Yellowtail and Three-spot Damselfish, but adult density was
highest for Cocoa and Beaugregory Damselfish and lowest in Yellowtail
Damselfish (Table 1). No juvenile Dusky Damselfish were found on either
2008 A.A. Wilkes et al. 487
Complex reef topography of branching corals like Acropora are thought
to be a major factor affecting reef fish distribution and abundance, and any
stressor that modifies coral morphology will likely have significant and
unpredictable impacts on associated reef fish populations (Lirman 1999).
Figure 2. Damselfish
density by species
( ± SE) on live
(A) and coral rubble
(B) in the Dry
marked with different
Table 1. Damselfish density by species and life stage ( ± SE) on live Staghorn Coral (Acropora
cervicornis) and coral rubble within the Dry Tortugas National Park, May 2004.
Live Staghorn Coral Coral rubble
Adult Juvenile Adult Juvenile
(fish/m2) (fish/m2) (fish/m2) (fish/m2)
Species (common name) N = 8 N = 8 N = 4 N = 4
Stegastes adustus 2.01 ± 1.078 Not observed 0.11 ± 0.390 Not observed
Stegastes variabilis 0.45 ± 0.711 0.002 ± 0.016 0.23 ± 0.291 0.35 ± 0.428
Stegastes leucostictus 0.24 ± 0.381 0.02 ± 0.082 0.23 ± 0.135 0.51 ± 0.570
Microspathodon chrysurus 0.50 ± 0.774 0.01 ± 0.047 0.01 ± 0.125 0.01 ± 0.059
Stegastes planifrons 0.94 ± 0.163 0.01 ± 0.047 0.05 ± 0.138 0.01 ± 0.060
488 Southeastern Naturalist Vol.7, No. 3
Within DTNP, loss of branching coral has resulted in an increase in rubble
habitat, which heavily favors juvenile fishes, while the more dimensionally
complex habitats offered by live Staghorn Coral are dominated by adults.
The higher adult numbers (three times higher than nearby rubble sites)
may indicate that branching habitat is more amiable to adult fish; however,
inflated adult densities resulting from a relative scarcity in branching corals
would also explain our findings. While it is unknown how important
resources may differ between rubble and live branching coral habitats,
greater fish densities in complex reef habitat have been linked to inherently
higher numbers of desirable territories for feeding, shelter, or reproduction
(Almany 2004, Holbrook et al. 2000) Despite the fact that pre-impact data
are not available, our study, although limited in scope, suggests that reductions
in damselfish density are the likely outcome in reefs where expanses
of live branching coral are in decline and are being replaced by relatively
low-dimensional fields of reef rubble.
Luckhurst and Luckhurst (1978) suggested that an increase in habitat
complexity also leads to an increase in reef fish species richness. However,
we observed the same damselfish species present on both coral rubble and
live Staghorn Coral sites. While no damselfish species found inhabiting live
Staghorn Coral were completely absent from the coral rubble habitat,
damselfish community structure displayed marked shifts. Dusky Damselfish
dominated on live Staghorn Coral, whereas Cocoa and Beaugregory
were dominant on coral rubble. Some damselfish species may require
habitat complexity provided by branching corals (Robertson 1984), whereas
others, such as Cocoa Damselfish, are better suited to exploit a wider range
of habitat types and display no specific coral preference (McGehee 1995,
Wallman et al. 2004). Fangue et al. (2001) found Cocoa Damselfish thriving
in hyperthermic and hypoxic tidepools on the northwest corner of Loggerhead
Key in DTNP. Damselfish species able to tolerate the widest range of
environmental conditions may dominate following a habitat disturbance.
Additionally, damselfish population relative to life stage differed signifi-
cantly between living Staghorn Coral and coral rubble. The number of adult
damselfish on live Staghorn Coral decreased by 85% relative to coral rubble
habitats, while the number of juvenile damselfish increased by 95%. Higher
adult density on live Staghorn Coral may be related to the increase in threedimensional
habitat that would provide predator refuge dimensions more
conducive to adult body sizes that require larger shelter spaces (Almany
2004, Holbrook et al. 2000, Nemeth 1998). Numerous smaller hiding spaces
along with relatively low adult densities may allow juvenile damselfishes to
more effectively exploit rubble habitats. Lirman (1994) reported that juvenile
Three-spot Damselfish on the Honduras Barrier Reef off Roatan Island
preferred dead coral. Similarly, our data showed juvenile damselfish reached
their highest density on coral rubble.
Implications of damselfish life-stage changes between reef and rubble are
not immediately clear. Coral rubble areas are always present to some degree
2008 A.A. Wilkes et al. 489
near branching coral reefs and probably serve as important nursery areas
to juvenile and sub-adult fishes before they recruit to the reef. Damselfish
larvae have a short dispersal time, typically two to five weeks, and fish are
not believed to recruit from distant reefs (Floeter and Gasparini 2000), but
rather settle in nearby areas (Paris and Cowen 2004, Sweatman 1985, Victor
1986). Lower recruitment and associated reduction in population size may
also result in potential loss of reproductive variability as well as decreased
physiological or behavioral plasticity.
If branching coral loss continues to exceed the reef rebuilding rate, the
decrease in adult numbers may affect damselfish recruitment throughout
DTNP, although some species may be less affected than others. Wallman et
al. (2004) reported patch reefs within DTNP supported populations of adult
Dusky, Cocoa, and Yellowtail Damselfish. These species may recover more
quickly on new Staghorn formations due to rapid recolonization from nearby
Given the important ecological role of damselfish as a keystone species,
it is likely that changing damselfish populations associated with loss
of branching coral will alter reef structure and fauna in DTNP. If Staghorn
Coral should begin to recover, it is unclear if damselfish and other reef
fish populations will revert to configurations seen prior to coral loss of the
1970s, or assume some new equilibrium. Coral reefs are sensitive habitats
that have not always recovered from environmental stressors. For example,
Caribbean reefs have never fully recovered from ecological consequences
associated with the Diadema antillarum population crash of 1983–84
(Chiappone et al. 2002).
There can be little doubt that coral reef ecology is shaped by relationships
between reef residents and corals that provide the structural habitat
underpinnings. Damselfishes are a notably important member for fish reef
fauna because they are known to directly shape structure and fish distribution
through their feeding and guarding behaviors (Almany 2004, Hixon and
Brostoff 1983). Our findings suggest that loss of branching coral habitats
from cold and disease (Davis 1982) have affected damselfish assemblages
in DTNP, and these changes could have broad implications to reef ecology
for not only the Florida reef track, but throughout the Caribbean. The extent
to which reefs may be affected by changing damselfish populations is hampered
by the dearth of available information; however, if changes in global
climate patterns continue, the possibility for further destruction of coral
reefs is high (Knowlton 2001, Smith and Buddemeier 1992), making this an
important topic of research in the future.
We thank the Dry Tortugas National Park Rangers and staff for their continued
support, knowledge, and guidance. We also thank the Florida Institute of Oceanography
and the crew of the R/V Bellows for much appreciated boat time, without which
this research would not be possible.
490 Southeastern Naturalist Vol.7, No. 3
Abrey, C.A. 2005. The effects of community on the territorial behavior of the Threespot
Damselfish. Environmental Biology of Fishes 73:163–170.
Almany, G.R. 2004. Does increased habitat complexity reduce predation and competition
in coral reef fish assemblages? Oikos 106:275–284.
Aronson, R.B., and W.F. Precht. 1997. Stasis, biological disturbance, and community
structure of a Holocene coral reef. Paleobiology 23(3):326–346.
Aronson, R.B., and W.F. Precht. 2001. White-band disease and the changing face of
Caribbean coral reefs. Hydrobiologia 460(1–3):25–38.
Bohnsack, J.A. 1983. Resiliencey of reef fish communities in the Florida Keys following
a January 1977 hypothermal fish kill. Environmental Biology of Fishes
Booth, D.J., and G.A Beretta. 2002. Changes in fish assemblage after a coral bleaching
event. Marine Ecology Progress Series 245:205–212.
Chiappone, M., D.W. Swanson, S.L. Miller, and S.F. Smith. 2002. Large-scale surveys
on the Florida Reef Tract indicate poor recovery of the Long-spined Sea
Urchin Diadema antillarum. Coral Reefs 21:155–159.
Clapp, F. 2005. The linking of coral disturbance, specifically the formation of “chimneys”
on Acropora palmata, to the Threespot Damselfish Stegastes planifrons.
M.Sc. Thesis. Florida State University, Tallahassee, FL.
Davis, G.E. 1982. A century of natural change in coral distribution at the Dry Tortugas:
A comparison of reef maps from 1881 and 1976. Bulletin of Marine Sciences
Emery, A.R. 1973. Comparative ecology and functional osteology of fourteen species
of damselfish (Pisces: Pomacentridae) at Alligator Reef, Florida Keys. Bulletin
of Marine Science 23(3):689–770.
Fangue, N.A., K.E. Flaherty, J.L. Rummer, G. Cole, K.S. Hansen, R. Hinote, B.L.
Noel, H. Wallman, and W.A. Bennett. 2001. Temperature and hypoxia tolerance
of selected fishes from a hyperthermal rockpool in the Dry Tortugas, with notes
on diversity and behavior. Caribbean Journal of Science 37(1–2):81–87.
Floeter, S.R., and J.L. Gasparini. 2000. The southwest Atlantic reef fish fauna:
Composition and zoogeographic patterns. Journal of Fisheries Biology 56:1099–
Hixon, M.A. and W.N. Brostoff. 1983. Damselfish as keystone species in reverse:
Intermediate disturbance and diversity on reef algae. Science 220:511–513
Holbrook, S.J., G.E. Forrester, and R.J. Schmitt. 2000. Spatial patterns in abundance
of a damselfish refl ect availability of suitable habitat. Oecologia 122:109–120.
Itzkowitz, M. 1977. Spatial organization of the Jamaican damselfish community.
Journal of Experimental Marine Biology and Ecology 28:217–241.
Itzkowitz, M. 1985. Aspects of the population dynamics and reproductive success
in the permanently territorial Beaugregory Damselfish. Marine Behavior and
Jaap, W.C. 2001. Coral reef restoration following anthropogenic disturbances. Bulletin
of Marine Sciences 69(2):333.
Jones, G.P. 1987. Some interactions between residents and recruits in two coral reef
fishes. Journal of Experimental Marine Biology and Ecology 114:169–182.
2008 A.A. Wilkes et al. 491
Knowlton, N. 2001. The future of coral reefs. Proceedings of the National Academy
of Sciences, USA 98:5419–5425.
Lieske, E., and R. Meyers. 1999. Coral Reef Fishes. Princeton University Press,
Lirman, D. 1994. Ontogenetic shifts in habitat preferences in the Three-spot Damselfish, Stegasees planifions (Cuvier), in Roatan Island, Honduras. Journal of
Experimental Marine Biology and Ecology 180:71–81.
Lirman, D. 1999. Reef fish communities associated with Acropora palmata: Relationships
to benthic attributes. Bulletin of Marine Sciences 65(1):235–252.
Longley, W.H., and S.F. Hilderbrand. 1941. Systematic catalogue of the fishes of
Tortugas, Florida with observations on color, habitats, and local distribution.
Papers from the Tortugas Laboratory of the Carnegie Institution of Washington
Luckhurst, B.E., and K.Luckhurst. 1978. Analysis of the infl uence of substrate variables
on coral reef fish communities. Marine Biology 49:317–323.
McGehee, M.A. 1995. Juvenile settlement, survivorship and in situ growth rates of
four species of Caribbean damselfish in the genus Stegastes. Environmental Biology
of Fishes 44:393–401.
Myrberg, A.A. 1971. Social dominance and territoriality in the Bicolor Damselfish,
Eupomacentrus partitus (Poey) (Pisces: Pomacentridae). Behaviour XLI:204–230.
Nemeth, R.S. 1998. The effect of natural variation in substrate architecture on
the survival of juvenile Bicolor Damselfish. Environmental Biology of Fishes
Paris, C.B., and R.K. Cowen. 2004. Direct evidence of a biophysical retention mechanism
for coral reef fish larvae. Limnology and Oceanography 49:1964–1979.
Porter, J.W., J.F. Battey, and F.J. Smith. 1982. Perturbation and change in coral reef
communities. Proceedings of the National Academy of Sciences 79:1678–1681.
Reaka-Kudlat, M.L., D.E. Wilson and E.O. Wilson. 1996. Biodiversity II: Understanding
and Protecting our Biological Resoursces. Joseph Henry Press, Washington,
Robertson, D.R. 1984. Interspecific competition controls abundance and habitat use
of territorial Caribbean damselfishes. Ecology 77(3):885–899.
Sale, P.F. 1972. Effect of cover on agonistic behavior of a reef fish: A possible spacing
mechanism. Ecology 53:753–758.
Smith, C.L. 2002. National Audubon Society Field Guide to Tropical Marine Fishes
of the Caribbean, the Gulf of Mexico, Florida, the Bahamas, and Bermuda. Alfred
A. Knopf, New York, NY.
Smith, S.V., and R.W. Buddemeier. 1992. Global change and coral reef ecosystems.
Annual Review of Ecological Systems 23:89–118.
Sweatman, H.P.A. 1985. The infl uence of adults of some coral reef fishes on larval
recruitment. Ecological Monographs 55:469–485.
Vargus-Angel, B., J.D. Thomas, and S.M. Hoke. 2003. High-latitude Acropora cervicornis
thickets off Fort Lauderdale, Florida, USA. Coral Reefs 22(4):465–473.
Victor, B.C. 1986. Larval settlement and juvenile mortality in a recruitment-limited
coral reef fish population. Ecological Monographs 56:145–160.
Wallman, H.L., K.J. Fitchett, C.M. Reber, C.M. Pomory, and W.A. Bennett. 2004.
Distribution of three common species of damselfish on patch reefs within the Dry
Tortugas National Park, Florida. Florida Scientist 67(3):169–176.
492 Southeastern Naturalist Vol.7, No. 3
Wellington, G.M. 1992. Habitat selection and juvenile persistence control the distribution
of two closely related Caribbean damselfishes. Oecologia 90:500–508.
Williams, A.H. 1979. Interference behavior and ecology of Threespot Damselfish
(Eupomacentrus planifrons). Oecologia 38:223–230.
Williams, A.H. 1980. The Threespot Damselfish: A noncarnivorous keystone species.
American Naturalist 116:138–142.
Williams, C. 1997. Diseased reefs alarm researchers. Geotimes 42(3):6.