Parrotfish
White Spot Biting
|
|
|
A
number of fish will eat coral tissue, including butterflyfish and
parrotfish. Signs of fish predation are very distinct from disease
signs. In coral tissue killed by disease the skeleton remains intact,
whereas fish predation generally involves the removal of live tissue
as well as the top layers of the skeleton. Butterflyfish, because
of their small, proboscis-like mouth, typically remove individual
polyps and tissue loss is very difficult to detect. Parrotfish leave
more prominent scars, which can be divided into two types:
1) multiple, small individual bite marks which are called "Spot
Biting"
2) multiple bites taken from one location on a colony, which is
termed "Focused Biting".
|
|
Spot
Biting
Stoplight parrotfish (S. viride) and several other large
parrotfish species frequently bite live coral, taking numerous small
bites that are scattered over the surface of coral heads. This behavior
creates obvious grazing scars that may be in pairs, formed by the
upper and lower jaws.
|
Close up of single bite marks from the stoplight parrotfish
|
Spot biting on lobate star coral, Montastraea annularis
|
In
some cases, an entire school of parrotfish will descend on a single
coral head, creating hundreds of bite marks. On close examination,
the bite marks on individual colonies will be in various stages,
including those that were recently created (exposed white skeleton
without any algal colonization) and those created days to weeks
earlier and have begun to heal (thin layer of tissue forming at
the margin of the injury, but polyps are not yet fully formed).
This type of predation is known as 'spot biting'.
|
|
Focused
Biting
Large
adult female and male stoplight parrotfish (Sparisoma viride)
often create large lesions on colony surfaces, returning to the
same coral head repeatedly to bite live tissue. These lesions progressively
spread across the coral, as fish remove the tissue and upper layers
of skeleton. On lesions that are being actively bitten by the fish,
mucus can be observed to stream off the injury, at the interface
between tissue and exposed skeleton.
|
Terminal
phase stoplight parrotfish biting on mountainous star coral, M.
faveolata
|
Focused
biting is observed most frequently on lobate star coral (Montastraea
annularis), where the fish may remove most of the tissue from
the upper surface of multiple lobes. Tissue typically remains at
the base of the lobe and will continue growing upward.
|
Focused
biting is also observed on mountainous star coral (Montastraea
faveolata), where fish will bite the edge of a coral (in plating
morphotypes) or elevated projections or knobs. |
|
A
number of other species may also be affected by parrotfish predation
including brain coral (Colpophyllia natans) where fish remove
tissue in a methodical pattern, starting at one end of the colony
and biting coral in a band that progressively radiates across the
coral.
|
Brain coral (C. natans) affected by focused biting. |
Stoplight parrotfish have removed the top surface of several polyps
of this flower coral (Eusmilia fastigiata). |
Parrotfish
Excrement
Stoplight
parrotfish, Sparisoma viride excrement on a branch of elkhorn
coral Acropora palmata
|
Parrotfish predation has been incorrectly referred to as rapid wasting
disease and rapid wasting syndrome, however detailed studies have
shown that no pathogenic organisms are involved in this process. |
