Ocean warming and acidification have complex interactive effects on the dynamics of a marine fungal disease.
Diseases threaten the structure and function of marine ecosystems and are contributing to the global decline of coral reefs. We currently lack an understanding of how climate change stressors, such as ocean acidification (OA) and warming, may simultaneously affect coral reef disease dynamics, particularly diseases threatening key reef-building organisms, for example crustose coralline algae (CCA). Here, we use coralline fungal disease (CFD), a previously described CCA disease from the Pacific, to examine these simultaneous effects using both field observations and experimental manipulations. We identify the associated fungus as belonging to the subphylum Ustilaginomycetes and show linear lesion expansion rates on individual hosts can reach 6.5 mm per day. Further, we demonstrate for the first time, to our knowledge, that ocean-warming events could increase the frequency of CFD outbreaks on coral reefs, but that OA-induced lowering of pH may ameliorate outbreaks by slowing lesion expansion rates on individual hosts. Lowered pH may still reduce overall host survivorship, however, by reducing calcification and facilitating fungal bio-erosion. Such complex, interactive effects between simultaneous extrinsic environmental stressors on disease dynamics are important to consider if we are to accurately predict the response of coral reef communities to future climate change.
Scripps Institution of Oceanography, Center for Marine Biodiversity and Conservation, University of California San Diego, , La Jolla, CA 92093, USA, Department of Microbiology, University of California San Diego, , La Jolla, CA 92093, USA, Joint Institute for Marine and Atmospheric Research, University of Hawaii at Manoa, , Honolulu, HI, USA, Hawaii Institute of Marine Biology, , Kaneohe, HI 96744, USA, School of Biological Sciences, Victoria University of Wellington, , PO Box 600, Wellington, New Zealand, Coral Reef Ecosystem Division (CRED), Pacific Islands Fisheries Science Center (PIFSC), , NOAA, 1610 Kapiolani Boulevard, Suite 1110, Honolulu, HI 96814, USA, US Geological Survey, National Wildlife Health Center, , Honolulu Field Station, PO Box 50167, Honolulu, HI 96850, USA.
Gareth J
GJ
Williams
Nichole N
NN
Price
Blake
B
Ushijima
Greta S
GS
Aeby
Sean
S
Callahan
Simon K
SK
Davy
Jamison M
JM
Gove
Maggie D
MD
Johnson
Ingrid S
IS
Knapp
Amanda
A
Shore-Maggio
Jennifer E
JE
Smith
Patrick
P
Videau
Thierry M
TM
Work
D000818:Animals; D037421:Anthozoa / Q000382:microbiology; D059001:Aquatic Organisms / Q000382:microbiology*; D057231:Climate Change; D057894:Coral Reefs; D006863:Hydrogen-Ion Concentration; D009792:Oceans and Seas; D011157:Population Dynamics; D012623:Seawater / Q000737:chemistry / Q000382:microbiology*
bio-erosion; climate change; coral reef; coralline fungal disease; ocean acidification; temperature