[Coral-List] new paper: Vulnerability of Coral Reefs to Bioerosion From Land-Based Sources of Pollution

[Storlazzi, Curt]

Dear colleagues,

For those of you interested in the role of reducing local coral reef
stressors to help increase the resiliency of coral reefs to global
stressors, please see the new paper published in the Journal of Geophysical
Research-Oceans by Prouty and others (see below). Although recent research
has highlighted how individual local stressors like overfishing and
nutrient run-off can independently impact corals, this study shows how
multiple local stressors, including acidity and nutrient levels, work in
concert to accelerate coral reef decline. This new research emphasizes how
coral reefs adjacent to densely populated shorelines are particularly
vulnerable to the effects of ocean acidification amplified by local
pollution.

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*Vulnerability of Coral Reefs to Bioerosion From Land-Based Sources of
Pollution*

Abstract:

Ocean acidification (OA), the gradual decline in ocean pH and [ [image:
math formula]] caused by rising levels of atmospheric CO2, poses a
significant threat to coral reef ecosystems, depressing rates of calcium
carbonate (CaCO3) production, and enhancing rates of bioerosion and
dissolution. As ocean pH and [ [image: math formula]] decline globally,
there is increasing emphasis on managing local stressors that can
exacerbate the vulnerability of coral reefs to the effects of OA. We show
that sustained, nutrient rich, lower pH submarine groundwater discharging
onto nearshore coral reefs off west Maui lowers the pH of seawater and
exposes corals to nitrate concentrations 50 times higher than ambient.
Rates of coral calcification are substantially decreased, and rates of
bioerosion are orders of magnitude higher than those observed in coral
cores collected in the Pacific under equivalent low pH conditions but
living in oligotrophic waters. Heavier coral nitrogen isotope (δ15N) values
pinpoint not only site-specific eutrophication, but also a sewage nitrogen
source enriched in 15N. Our results show that eutrophication of reef
seawater by land-based sources of pollution can magnify the effects of OA
through nutrient driven-bioerosion. These conditions could contribute to
the collapse of coastal coral reef ecosystems sooner than current
projections predict based only on ocean acidification.

American Geophysical Union's blog:

*https://blogs.agu.org/geospace/2017/11/01/polluted-groundwater-eroding-hawaiian-coral-reefs-study-shows/
<https://blogs.agu.org/geospace/2017/11/01/polluted-groundwater-eroding-hawaiian-coral-reefs-study-shows/>​*

Link:

*http://onlinelibrary.wiley.com/doi/10.1002/2017JC013264/abstract
<http://onlinelibrary.wiley.com/doi/10.1002/2017JC013264/abstract>*
http://onlinelibrary.wiley.com/doi/10.1002/2017JC013264/full
http://onlinelibrary.wiley.com/doi/10.1002/2017JC013264/epdf


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Curt D. Storlazzi, Ph.D.
U.S. Geological Survey
Pacific Coastal and Marine Science Center
2885 Mission Street
Santa Cruz, CA 95060
(831) 460-7521 phone
(831) 427-4748 fax

Staff web page:
https://www.usgs.gov/staff-profiles/curt-d-storlazzi
Coral Reefs:
*https://coralreefs.wr.usgs.gov/ <http://coralreefs.wr.usgs.gov/>*
Sea-level Rise and Atolls:
*https://walrus.wr.usgs.gov/climate-change/atolls/
<http://walrus.wr.usgs.gov/climate-change/atolls/>*