[Coral-List] New paper: coral reef marine fungal disease dynamics

[Benjamin Neal]

Dear colleagues,

Please have a look at our recent paper on crustose coralline algae disease
dynamics. Reef diseases of all types can can involve complex multi-species
interactions, and this work details an example of this, in this case
between crustose coralline algae, a marine fungal disease agent, and
herbivorous fish. In summary, nominally herbivorous fish were observed
directly consuming the fungal disease agent, and thus possibly reducing
disease extent. This targeting of marine fungus for consumption, a
heretofore undescribed behavior, may not only affect disease progression,
but may also be another reason to preserve healthy populations of reef
herbivores.

Please find this open-access publication in Oecologia here
<https://link.springer.com/article/10.1007/s00442-020-04697-7>. Thank you,
Ben Neal

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*Abstract**:* Primary producers in terrestrial and marine systems can be
affected by fungal pathogens threatening the provision of critical
ecosystem services. Crustose coralline algae (CCA) are ecologically
important members of tropical reef systems and are impacted by coralline
fungal disease (CFD) which manifests as overgrowth of the CCA crust by
fungal lesions causing partial to complete mortality of the CCA host. No
natural controls for CFD have been identified, but nominally herbivorous
fish could play a role by consuming pathogenic fungi. We documented
preferential grazing on fungal lesions by adults of six common
reef-dwelling species of herbivorous Acanthuridae and Labridae,
(surgeonfish and parrotfish) which collectively demonstrated an ~ 80-fold
higher grazing rate on fungal lesions relative to their proportionate
benthic coverage, and a preference for lesions over other palatable
substrata (e.g. live scleractinian coral, CCA, or algae). Furthermore, we
recorded a ~ 600% increase in live CFD lesion size over an approximately
2-week period when grazing by herbivorous fish was experimentally excluded
suggesting that herbivorous reef fish could control CFD progression by
directly reducing biomass of the fungal pathogen. Removal rates may be
sufficient to allow CCA to recover from infection and explain historically
observed natural waning behaviour after an outbreak. Thus, in addition to
their well-known role as determinants of macroalgal overgrowth of reefs,
herbivorous fish could thus also be important in control of diseases
affecting crustose coralline algae that stabilize the foundation of coral
reef substrata.

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*Benjamin P NealAssistant Professor, **Environmental Studies Program*
*Colby College, **4026 Mayflower Hill*
*Waterville, Maine 04901  *
*C: (207-509-4404)*