TROPICAL FISH HOBBYIST 51(5) 82-90
Aquarium Science
Colour Morphs in a Queen Angelfish Holacanthus ciliaris
(Perciformes: Pomacanthidae)
population of St. Paul’s Rocks, NE Brazil.
Osmar J. Luiz-Júnior with photographs by the author
Núcleo e Agência Ambiental, Universidade Metodista de São Paulo,
Rua do Sacramento, São Bernardo do Campo, SP, Brazil, 09640-000. E-mail: [email protected]
Abstract
Some colour variations in the Queen Angelfish (Holacanthus ciliaris) are
shown in this paper. These morphs belong to an isolated population resident
at Saint Paul’s Rocks, a group of small islands in the tropical central Atlantic.
Some factors like homozygous following inbreeding and low genetic flow
are considered the probably causes of this phenomenon.
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January 2003
INTRODUCTION
The occurrence of color morph
variations has been documented
for some species of reef fishes of
the families Serranidae (Graves &
Rosenblatt 1980; Medioni et al.
2001), Cirrhitidae (DeMartini &
Donaldson 1996), Syngnathidae
(Guimarães 1999), Ostraciidae
(Pattengill-Semmens 1999) and
Pomacentridae (Planes & Doherty
1997). Among Pomacanthids, a
case of melanism in Holacanthus
tricolor was detected south of the
Caribbean island of Porto Rico
(Colin 1982). Holacanthus ciliaris
is a common reef fish species of
St. Paul’s Rocks (Feitoza et al. in
press) and its color variants there
were first reported by members
of the Cambridge Expedition to
St. Paul’s Rocks in 1979 (Lubbock
& Edwards 1981; Edwards &
Lubbock 1983) but there are no
additional registers for H. ciliaris
color morphs in the entire
spectrum of their geographic
range. In a recent visit to the Rocks
I had the opportunity to make a
photographic register of many of
these bizarre fishes. All the color
variations observed in H. ciliaris
are presented in this paper.
METHODS
St. Paul’s Rocks are an oceanic
group of small islands located 960
km off the northeast coast of
Brazil, lying just north of the
equator (00°55’N; 29°21’W). They
are emerged bits of the MidAtlantic Ridge, caused by an up
thrust of the oceanic upper mantle
(Melson 1966). A general account
of they’re ecology is provided by
Edwards & Lubbock (1983a).
I visited the Rock’s as a
member of a documentary
expedition in november/1999. On
that occasion, 16 dives were
made and a total of
Tropical Fish Hobbyist
Above: This is the normal coloration of H. ciliaris, as found off the continental Brazilian coast.
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Opposite: The coasts of St. Paul’s Rocks in the Atlantic are home to a number of unique color
variants of the queen angelfish, Holacanthus ciliaris. The most common is the golden one,
photographed in its natural habitat.
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approximately 20 hours of
underwater observations were
completed.
The fishes were photographed
using a reflex still camera in an
underwater housing loaded with
color slide or negative film. They
are also filmed with a digital miniDV camcorder camera in an
underwater housing.
RESULTS
The following types of H.
ciliaris color morphs were found:
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PALE CAUDAL FIN
• BRIGHT BLUE MORPH WITH A
PALE CAUDAL FIN AND YELLOW
FACE
• BRIGHT BLUE MORPH WITH
YELLOW CAUDAL AND PECTORAL
FINS
• BRIGHT BLUE MORPH WITH
BLACK AND WHITE CAUDAL AND
PECTORAL FINS, WHITE
OPERCULE AND MOUTH
• GOLD MORPH
This is the predominant
coloration in the St. Paul’s
population and differs from the
Brazilian coast and Caribbean
populations by having a bright
orange coloration in the body in
contrast to the normal pattern of
yellow and blue body color. The
Saint Paul’s population also has
shorter tips of the dorsal and anal
fins, which do not reach the end
of the caudal fin.
• ALL WHITE MORPH
• WHITE MORPH WITH ORANGE
AND BLACK BLOTCHES
• BRIGHT BLUE MORPH WITH A
DISCUSSION OF GENETIC AND
BIOGEOGRAPHIC CONJECTURES
The occurrence of intraspecific
color morphs in fish populations
are relatively common and can be
attributed to many reasons, such
as (1) ontogeny; (2) behavioural
responses and communication,
and (3) genetic differentiation.
When the colour changes are a
result of ontogeny or by induced
responses of the skin pigments,
they could be variable with the
age of the fish, time of day, and
social interactions (e.g. Nemtzov
1993) and could be distributed all
along the species’ geographic
82
Above: The predominant morph at St.
Paul’s Rocks, the golden.
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Below: The all white morph.
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range as an intrinsic characteristic
of the species in question.
Fixed and permanent changes
in color patterns are attributed to
genetic differentiation, and its
short-term development must be
associated with an isolated
population or with a population
that was isolated in the past. This
differentiation tends to occur
faster in small populations
(Palumbi 1994).
The colour variations occurring
in the H. ciliaris population of St.
Paul’s Rocks were interpreted as
evidence of inbreeding in an
isolated population (Edwards &
Lubbock 1983b). One of the most
recognized effects of inbreeding
in a population is the trend to
higher
frequencies
of
homozygous genes and the
consequent manifestation of
84
recessive traits (Futuyma 1986).
The variations are strong
evidence that the St. Paul’s
population is not receiving, or is
receiving a very few H. ciliaris
recruits from the mainland or
from the closest islands of
Fernando
de
Noronha
Archipelago.
The causes of the H. ciliaris
isolation are not clear and
contradictory
with
the
observation that most of the reef
fishes of St. Paul’s Rocks are
brought from the Brazilian coast
or Fernando de Noronha by the
Equatorial Undercurrent (Bowen
1966; Edwards & Lubbock 1983).
Despite their widespread
distribution in the Tropical
Western Atlantic and the many
examples of the long dispersal
capabilities of some tropical reef
fishes (Joyeux et al. 2001), H.
ciliaris are not found in other
extremely isolated oceanic
January 2003
obs.) should contribute to the
isolation of St. Paul’s population
by providing a very little output
of recruits (and consequently low
genetic flow). The St. Paul’s
population of H.ciliaris are thus
probably maintaining themselves
mainly by self-recruitment
(Swearer et al. 1999; Jones et al.
1999; Robertson 2001).
A PLEA FOR CONSERVATION
Above: A white with orange and dark splotches morph.
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Below: An impossible sight-except at St. Paul’s Rocks, were these two color variants of
H. ciliaris are encountered.
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islands in the South Atlantic
(Lubbock 1980; Gasparini &
Floeter 2001). St. Paul’s Rocks are
the farthest location inhabited by
H. ciliaris in the South Atlantic,
and it probably reaches the Rocks
utilizing Atol das Rocas and/or
Fernando
de
Noronha
Archipelago as stepping-stones
86
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for colonization. The icthyofauna
of these islands are, in fact,
considered very similar in a recent
biogeographic analysis (Floeter &
Gasparini 2000). Despite its
relative proximity, the very low
density of H. ciliaris in the
Fernando
de
Noronha
Archipelago (SR Floeter pers.
It is clear that marine species
are not exempt from human
impacts and extinction risk
(Roberts & Hawkins 1999;
Hawkins et al. 2000). Our
observations show that this
population of H. ciliaris posses
some risk characteristics:
(1) Restrict geographic range.
As defined by Robertson (2001),
genetically distinct isolated
populations, as in this case,
should be treated as endemic
species. The only putative case of
extinction registered for a reef fish
was an island-endemic species
(Roberts & Hawkins 1999).
(2) Importance in the
aquarium trade. The isolation of
St. Paul’s Rocks is not an obstacle
January 2003
Above: This angel morph has a bright blue
body with a pale caudal fin.
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Below: This specimen seems to be
intermediate between the normal coloration
and the golden variety.
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obs.).
(4) Another risk not included in
these conservation accounts is
the possibility of inbreeding
depression. Isolated inbred
populations have a greater
chance to manifest deleterious
features that can lead the
population to local extinction
(Frankhan 1998).
ACKNOWLEDGMENTS
for the commercial capture of this
fishes for the aquarium trade,
since the collection of some
exemplars were recently
observed (B.M. Feitoza pers.obs.).
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(3) By-catch in the lobster
fishery. Some exemplars were
observed trapped in the lobster
traps utilized by commercial
fishers (O.J. Luiz-Júnior pers.
The author thanks Bertran
Feitoza and Eleonora Fritzsche.
Fabio B. Pereira for diving support
during the expedition. Captain
João C. Marenga and the crew of
“Aussteiger” sailboat. Sergio R.
Floeter and João L. Gasparini for
comments and for reviewing the
manuscript.
January 2003
The depths around St. Paul’s Rocks contain a wide variety of unique queen angel color morphs.
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