[Coral-List] new paper on coral reef ecosystem metabolism

[Katie Shamberger]

Hi all,
I wanted to share some exciting new work our lab just published in
Geophysical Research Letters, “Heterotrophy of Oceanic Particulate Organic
Matter Elevates Net Ecosystem Calcification”, led by Dr Andrea Kealoha.
The full citation, abstract, and plain language summary are below.

Katie Shamberger

link to paper:
https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083726

Kealoha A.K., Shamberger K.E.F., Reid E., Davis K.A., Lentz S.J., Brainard,
R., Oliver T., Rappe M., Roark E.B., Rii S. 2019. Heterotrophy of oceanic
particulate organic matter elevates net ecosystem calcification.
Geophysical Research Letters. https://doi.org/10.1029/2019GL083726

Abstract
Coral reef calcification is expected to decline due to climate change
stressors such as ocean acidification and warming. Projections of future
coral reef health are based on our understanding of the environmental
drivers that affect calcification and dissolution. One such driver that may
impact coral reef health is heterotrophy of oceanic‐sourced particulate
organic matter, but its link to calcification has not been directly
investigated in the field. In this study, we estimated net ecosystem
calcification and oceanic particulate organic carbon (POCoc) uptake across
the Kāne'ohe Bay barrier reef in Hawai'i. We show that higher rates of POCoc
 uptake correspond to greater net ecosystem calcification rates, even under
low aragonite saturation states (Ωar). Hence, reductions in offshore
productivity may negatively impact coral reefs by decreasing the food
supply required to sustain calcification. Alternatively, coral reefs that
receive ample inputs of POCoc may maintain higher calcification rates,
despite a global decline in Ωar.

Plain Language Summary
Coral reefs are threatened by climate change stressors including ocean
acidification and ocean warming. One way to measure and monitor coral reef
health is to estimate coral reef calcification, which is influenced by
several environmental factors including light, temperature, pH, and
nutrient availability. By understanding the effects of these factors on
calcification, we can better predict how corals will respond to climate
change. One potentially important factor for calcification that has not
been investigated in the field is coral reef ecosystem feeding on
particulate organic matter supplied from offshore (i.e., oceanic
particulate organic matter). In this study, we estimated net ecosystem
calcification and oceanic particulate organic carbon (POC) uptake across
the Kāne'ohe Bay barrier reef in Hawai'i. For the first time, we show a
direct correlation between net ecosystem calcification and oceanic POC
uptake, which suggests that the reef is using oceanic POC as an energy
source to elevate calcification. However, since climate change reduces
oceanic POC production through warming and stratification, our results
imply coral reef calcification may decline. Alternatively, coral reefs
located in regions of high oceanic productivity and that sustain greater
rates of oceanic POC uptake may be able to maintain calcification longer
into the future.



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Kathryn E. F. Shamberger
Assistant Professor
Department of Oceanography
Texas A&M University
College Station, TX 77843
1-979-845-5752
katie.shamberger at tamu.edu
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