Butterflyfishes as Indicators of change

[kochzius at uni-bremen.de]

Hi Victor!

The indicator hypothesis of Chaetodontidae to asses the "health" of a coral 
reef is still under debate. There are many studies that faild to find a 
relationship, whereas other found a strong one. From my experience in fish 
community analysis on coral reefs and the literature of that field, I would 
state that simply counting Chaetodontidae will not give an indication about 
the reef "health". There are several points that should be considered:
1. What will be the definition of reef "health"?
2. There are several chaetodontid species that do not feed on corals at all 
or feed on corals and other benthic invertebrates > as Anthony Mazeroll 
already mentioned, you need to know about the diet of the species you 
count. The focus should be on obligate corallivores.
3. It might be better to consider corallivorous fishes rather than 
Chaetodontidae (there are several species of other families that feed on 
corals)
4. In my data analysis I found a stronger correlation of corallivorous 
fishes to live hard coral cover than of Chaetodontidae to live hard coral 
cover.
5. Impact of fishing might be a problem as well. I heared from a colleague 
that Chaetodontidae tend to enter bamboo traps that are used to catch 
fusiliers (Caesionidae). However, as far as I know there is no publication 
on this topic.

As other authors already mentioned, ther are to many uncertainties in the 
use of butterflyfishes as indicators. The intention of indicator species is 
to have a rapid method for the assesment of the environment of this 
species. From my point of view a proper assesment of the abundance and 
behaviour (you need to study this as well) of Chaetodontidae is as time 
consuming as a detailed survey of the benthic habitat (corals).

Best fishes

Marc


At 19:17 19.05.01 +0930, you wrote:

>Dear Colleagues,
>
>I would like to find if anyone is using Butterflyfishes as Indicators of
>coral reefs conditions?:
>Re: Crosby, M.P. and E.S.Reese. 1996 A Manual for Monitoring Coral Reefs
>With Indicator Species: Butterflyfishes as Indicators  of Change on Indo
>Pacific Reefs. Office of Ocean and Coastal Resource Management, NOAA, Silver
>Spring, MD. 45 pp.
>
>Your feedback will be greatly appreciated.
>
>
>Regards,
>
>Dr Victor E. Gomelyuk
>Marine Scientist
>Cobourg Marine Park
>PO Box 496 PALMERSTON NT 0831 AUSTRALIA
>phone 61 (08) 8979 0244
>FAX 61 (08) 8979 0246
>
>
>
>
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