[Coral-List] SCTLD spread by butterfly fish.

[International Coral Reef Observatory]

In previous messages, some scientists mentioned that associations are not
proof of causation. Nevertheless in your cited paper the word association
is written 14 times in the text (Inclusive once in the title and 4 times in
the abstract): "Association of foureye butterflyfish with particular
diseased corals decreased from 2018 to 2019 as the SCTLD infections
disappeared". We all know that with a decline in healthy and live coral
cover, these fish will move away from an affected reef to seek out
healthier reefs for sustenance.
There is a fact that some of the 129 species of butterflyfish
(Chaetodontidae) feed on coral mucus as they have been acknowledged as
“mucus munchers”. Thus, they take advantage of energy-rich coral mucus as a
primary food source. Before removing them from a coral reef area, it is
necessary to evaluate its important ecological role in healthy coral reefs.

According to  Hourigan and  Tricas (1988) Butterflyfishes are obligate
corallivores, and thus depend on the live tissue of corals for their food
and they are excellent candidates for indicators of changes in conditions
on the coral reef
https://www.researchgate.net/publication/236625136_Coral_Reef_Fishes_as_Indicators_of_Environmental_Stress_in_Coral_Reefs


Perhaps they are serving as biological controllers of the infection per
colony; instead of contagious vectors. Definitively, they are not the
primary cause of SCTLD as there should be another factor that causes the
coral colonies to produce mucus in the first place may be an external
stressor (New Pollutant or human intensive activity going on those coral
reefs).

Noonan and Childress (2020) suggest that foureye butterflyfish recruit to
and feed on SCTLD-infected corals which may influence the progression
and/or transmission of this insidious coral disease. Considering the notion
that the direct contact of the fishes with the sick coral colonies as a
vector, may be relevant to apply to any kind of fauna or humans touching
the colonies carrying the mucus from one site to another. Hence the
rationale of the precautionary principle to avoid further massive human
activities in the infected areas preventing visiting other healthy coral
reef areas without disinfecting scuba gear.

Nohora Galvis
ICRS World Reef Award Winner
ICRO Transdisciplinary Researcher
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