Butterfly fish (Family
Chaetodontidae) are one of the most conspicuous of the fish species inhabiting
coral reefs worldwide, due to their beautiful colour, distinctive markings,
morphology and interesting social behaviour. Butterfly fish species remain
close to coral reefs all their lives as research shows these fish depend on
coral species and other reef organisms for food, habitat and protection from
predators. Generalist feeders (that rely on a variety of food sources in
addition to coral species) are less common than butterfly fish that consume only
corals and experience slower growth rates than their corallivorous
counterparts.
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Butterfly fish swimming in its coral reef habitat. Photo © Anje Ranneberg
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Interestingly, some
butterfly fish species have a preference for a particular species of coral so
their habitats location might be linked to the type and amount of coral substrate
present at various locations along the reef. The reefs exposure to the currents
and the protection it provides against egg predators might also be reason’s influencing
fish preference for a location over other sites. Studies have revealed some butterfly
fish species have a home range they explore to forage for food.
As juveniles, butterfly
fish have been observed to find a monogamous mate. This type of pairing early
in development decreases the stress levels experienced by these fish, for
example, they expend less energy defending their home range or competing with
other butterfly fish to reproduce. The constraints that solitary fish or fish
living in a harem experience, may play to their favour. Female territories have
been observed close to the male, which allows the male to protect and maintain
his territory, resulting in less energy being used, much like the monogamous pairs
but with multiple chances for fertilising opportunities.
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Coral reef habitat. Photo © Vincenzo Piazza
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Butterfly fish use
complex forms of social and mating behaviour to exploit the ecological
advantages available on the coral reef. Their courtship patterns are an
interesting window to their survival. Some butterfly fish mate before sunset.
This timing reflects their natural behavior but also increases the chances of
egg survival from predation by other fish. Some rogue male butterfly fish are
opportunistic and intrude on a spawning monogamous pair by attempting to
fertilise the female’s eggs with their own gametes.
Once the eggs of butterfly
fish hatch, larvae usually settle close to their native spawning grounds, but
this can be a temporary strategy to avoid predators or to find food quickly
while migrating to another site. Many view habitat destruction from storms and
cyclones negatively, but in the marine environment they have a positive affect,
because the amount of coral reef refuge for butterfly fish larvae to settle in
increases.
Colour might also be a
reason for the success of butterfly fish in coral reef environments. Butterfly
fish species are well known for their beautiful markings, which might protect individuals
from attack by their counterparts or assist mate recognition. Other cues
butterfly fish use to identify their mates from other fish are the sounds they
make, for example, some make grunting noises while others slap their tails. So
a combination of colour and sound cues improves the success of mating,
territorial protection and defence against predators.
Butterfly fish are linked
to coral reefs through their colour, morphology, social behavior, courtship,
mating patterns and the sounds they make. Their dependence on coral species for
food, protection and recruitment, highlights their potential as a coral reef
health indicator species. Coral species are experiencing declines from the
effects of warmer oceans, smothering from sediment, disturbance from
infrastructure development and fishing pressures.
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Green sea turtle swimming off the Hawaii Islands. Photo © Chris LaCroix
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A combination of all
these factors and pressures from the natural environment are creating extreme
conditions coral species cannot withstand for long periods of time. Although
present studies are working to identify tolerant species of coral that cope
with more hostile environments, alternative methods can also be pursued, by
protecting coral reefs through expanding marine parks and reducing the
activities that are causing their decline both in the marine and terrestrial
environments.
Research studies provide
evidence of how coral reefs, other marine habitats and associated plants and
animals are being affected. These studies have not just been completed in the
last few years but over centuries. Considering the weight of evidence that is
available to read; and the benefit provided by the natural environment, you have
to wonder why the facts presented by scientific research to reduce negative
activities are continually being ignored.
Butterfly fish are more than just a fish species swimming around coral reefs, they have developed different ways to communicate with one another, using colour, movement and sound, creating an unforgettable panorama of beauty on many levels.
Written by Gabrielle
Ahern
Salty Wave Blue – Into all things
ecology.
Follow @SaltyWaveBlue on
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If you would like to see images
of animals in their environment, especially butterfly fishes and
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