[Coral-List] butterflyfish and SCTLD

[Mark Tupper]

Hi Alina, Steve, et al., Sorry for the repeat message - my mails were not
making it to the list.

Where has it been proven that foureye butterflyfish are vectors of SCTLD?
The Noonan and Childress (2020) paper that described the relationship
between foureye butterflyfish and SCTLD specifically does not conclude that
foureye butterflyfish are a vector. It  shows a strong association between
the fish and the disease, but as the saying goes, correlation does not
equal causation. When the disease started, foureyes showed up to feed on
the diseased coral tissue. When the disease disappeared, so did the fish. I
saw the same thing in St. Lucia in 2019.

The key sentence in the Noonan and Childress paper is "If butterflyfish
were facilitating the spread of SCTLD, we would expect to find faster rates
of new infection in areas with higher butterflyfish abundance, but if coral
disease is increasing butterflyfish recruitment after initial infection,
disease spread would not necessarily be related to butterflyfish
abundance". As far as I know, nobody has found that SCTLD spreads faster in
areas with high existing densities of foureye butterflyfish. Certainly,
in St. Lucia, the disease showed up at my sites before the butterflyfish. To
me it seems just as likely that the butterflyfish may assist the coral in
recovery by opportunistically feeding on the diseased polyps, as opposed to
being the cause of the spread. I agree with Alina - killing a keystone
ecological species because you think it may be spreading disease is a bad
idea.

In fact, here is a more recent (2022) paper on SCTLD and butterflyfish that
conducted feeding experiments to see whether foureye butterflyfish spread
the disease. The authors concluded that the butterflyfish were not a vector
and may instead be increasing infection recovery.

Frontiers | The Influence of Foureye Butterflyfish (Chaetodon capistratus)
and Symbiodiniaceae on the Transmission of Stony Coral Tissue Loss Disease
(frontiersin.org)
<https://www.frontiersin.org/articles/10.3389/fmars.2022.800423/full>

Cheers,
Mark
-- 
Dr Mark H Tupper PhD, CFP, FMBA
Theme Lead - Aquatic Living Resources Management, Centre for Blue Governance
Institute of Marine Sciences, School of Biological Sciences

University of Portsmouth, Ferry Road, Portsmouth PO4 9LY

T: +44 (0)23 9284 5082; E: mark.tupper at port.ac.uk
<darren.mernagh at port.ac.uk>

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