butterflyfishas indicator of reef species

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Prepared by Hermon Ghebreslassie Id/No
12/027

Advisor Mr Selvam R Nath
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Introduction

• Coral reefs are beautiful vibrant underwater
  cities, home to one hundred thousand different
  species of sea creatures.
• Coral reefs are only found in tropical and
  sub-tropical waters around the world. However,
  since ocean currents can bring warm water to
  cooler places, reef corals grow in surprising
  locations. Coral reefs in different parts of the
  world vary in the number and composition of coral
  species.
• Corals are fundamental in providing essential
  habitat and resources for numerous sedentary and
  mobile organisms.
• Corallivorous ?shes are foremost in their
  association ,with coral habitats, as they have an
  obvious dependence on corals for food in addition
  to shelter and living space.

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• corals were largely inaccessible as a viable prey
  source, and that there were very few ?shes
  capable of feeding directly on corals.
• corallivorous ?shes impose more permanent and
  chronic pressures on scleractinian corals and are
  thus assumed to have limited overall impact on
  prey corals .
• Corallivorous ?shes are generally assumed to have
  very minimal in?uence on distribution, abundance
  or community structure of potential prey corals
• Corallivorous they feed-
• coral mucous (e.g. Ornate butter?y ?sh, Chaetodon
  ornatissimus, Chaetodontidae),
• coral polyps (e.g. chevron butter?y ?sh,
  Chaetodon trifascialis, Chaetodontidae)
• coral skeleton (guieneafowl puffer, Arothron
  meleagris, Tetraodontidae).
• coral cover and the abundance of corallivores,
  primarily chaetodontids

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• How widespread is corallivory?
• -corallivory is taxonomically wide spread,
  and has been documented in at least 128 species
  and 11 reef-?sh families.
• While the butter?y ?sh account for just over half
  of the known corallivores (69 species), this
  feeding mode is
• other families such as the- Labridae,
  Tetraodontidae, Monacanthidae, Pomacentridae,
  Scaridae and Balistidae, which all have between
  seven and ten corallivorous species

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• Role of Corallivores in coral reef ecosystem
• Estimation of coral consumption by Corallivores
  are fundamental to understanding their role in
  coral reef dynamics.
• Given the substantial number of ?sh species that
  feed on corals it is likely that the Corallivores
  link in the coral reef food web.
• Corallivorous ?shes have some of the longest
  intestines of all ?shes which facilitates high
  gut retention times and may allow the digestion
  of wax easters.
• logically, on higher-diversity reefs the depth of
  corallivore interactions with the coral community
  will likely increase, thus increasing the net
  transport of energy up the food web.
• mortality associated with predation is often
  cited as being very low, at least for coral
  feeding butter?y ?sh .Individuals of several
  coral-feeding butter?y ?sh have been observed
  occupying the same home ranges over several years
  ,as they are relatively long-lived.
• Types of corallivorous
• Corallivorous ?shes can be broadly divided into
  obligate corallivores or facultative corallivores
• Corallivores as obligate when more than 80 of
  their diet is centred on coral ,these species are
  highly dependent on coral for their survival

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• Coral feeders primarily target scleractinian
  (hard) corals,
• although several species (e.g. black-backed
  butter?y ?sh, Chaetodon melannotus,
  Chaetodontidae) feed extensively on alcyonarian
  (soft) corals

• Chaetodon melannotus

• Butter?y fishes are the only corallivores found
  to consume soft coral all other corallivorous
  families have only been observed to feed on
  scleractinian coral.

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Spatial variation during dietary composition

• The dietary composition of individual corallivore
  species can vary among geographic locations and
  between habitats.
• The adaptation to feed on coral is largely
  con?ned to the Indo-Paci?c and the Red Sea.
• Impact of corallivores on the coral communities
• The majority of corallivorous ?shes can be
  classed as polyp-feeders, removing coral tissue
  without harming the underlying corallite.
• They have a limitation on their feeding behaviour
  
• concentrate feeding on only a subset of coral
  species
• To maintain their on going food source
• A balance must be met between feeding intensity
  and coral regeneration

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Others coralivores ingest large amount of biting
of growing tips- (balestids tetradontids).

• Corallivores have a dual role on reefs in
  addition to being a coral predator they are also
  important in reef association through
  bio-erosion.
• The amount of material removed by corallivores
  who ingest skeletal material.eg, guineafowl
  puffer, teardrop butter?y ?sh
• Availability of teardrop butter?y ?sh decreased
  the ability of Montipora verrucosa to compete
  for space.
• pocilopora compressa
• The impact of corallivory may be more seen under
  conditions where coral has been depleted owing to
  other disturbances .

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THE CONCEPT OF INDICATOR SPECIES

• Butterfly fishes of the family Chaetodontidae are
  visible inhabitants of coral reefs throughout the
  world.
• Many species are obligate Corallivores, they
  depend on live tissue.
• Because their metabolic or energetic demand
  linked to the overall condition or "health" of
  the coral.
• They are indicators of changes in conditions on
  the coral reef.
• They are intimately related on which they fed.
• The distribution and abundance of these fishes
  should be directly correlated with the
  distribution and abundance of the corals.

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• If the corals are adversely affected by
  stressful environmental conditions, such as
  chronic low levels of pollution, their health
  will deteriorate.
• This deterioration should be detected by the
  fishes which feed on them. In many species of
  organisms, sub-lethal levels of stress cause
  reallocation of available energy.
• first proposed that obligate Corallivores, such
  as many species of butterfly fishes, could serve
  as indicator organisms.
• Behavioural Ecology of Butterfly fishes
• The butterfly fishes, are found in all tropical
  seas of the world.
• 114 species in 10 genera
• diurnally active brightly colored.
• monogamous pairs and broadly territorial
• There is preferential mating and pair bond
  formation based on size.
• They are dusk and broadcast spawners ,no parental
  care
• Coral feeder chaetodontids have high degree of
  faithfulness with same individual in the same
  territories
• Life span is 10 to 12 years

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Behavioural Ecology of Butterfly fishes

• The butterfly fishes, are found in all tropical
  seas of the world.114 species in 10 genera
• diurnally active brightly colored.
• monogamous pairs and broadly territorial
• There is preferential mating and pair bond
  formation based on size.
• They are dusk and broadcast spawners ,no parental
  care
• Coral feeder chaetodontids have high degree of
  faithfulness.
• with same individual in the same territories
• Life span is 10 to 12 years
• butterfly fishes ideal candidates for indicator
  species of ecological conditions on coral reefs.

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Butterfly fishes as Indicator Species

• sensitive biotic indicators are most useful when
  one wishes to detect low levels of chronic alarms
  such as low levels of chemical pollutants or
  small changes in temperature or nutrient levels.
• Over time such low levels of chronic alarms can
  have marked harmful effects on the ecosystem they
  are impacting.
• Yet it is extremely difficult and expensive to
  develop a sampling system to detect such low
  levels.
• Under such condition that sensitive biological
  indicators are most useful.

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• First doesnt need a sensitive indicator for
  occurring irregular interval, terrible events
  like oil spills or storms.
• The second point of importance is that not all
  chaetodontids are candidates for indicator
  species.
• The planktivores are feed on planktons and the
  omnivores feed up on benthic invertebrate, coral
  on algae So as the prey changes.
• The coral feeding chaetodontids make ideal
  indicators because they are directly dependent on
  the corals.
• obligate corallivores and do not feed on anything
  else.
• They show strong preferences for certain species
  of corals which provides a further dimension of
  sensitivity to the system.
• Since they are territorial, strongly site
  attached, and live for many years

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• If changes happens slowly, the corals will
  decline through time
• A reef which is dead from siltation or from
  crown-of-thorns no longer has its characteristic
  meeting of coral feeding chaetodontids.
• There appears to be a beginning level of reef
  deterioration at which the fishes begin to leave,
  
• The size of Corallivores butterfly fishes
  territories are determined by the amount of coral
  food contained there in
• removal of coral from territories results in
  pairs of fish attempting to enlarge their
  territories at the expense of their neighbours
  which results in increased conflict level of
  behaviour.

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Conclusion

• At last as number of paired butterfly fishes
  increased in the territory the coral community is
  not deteriorate much but through certain effect
  it could have a chronic effect

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