Journal article
Has Nitrogen Supply to Coral Reefs in the South Pacific Ocean Changed Over the Past 50 Thousand Years?
Paleoceanography and Paleoclimatology, Vol.34(4), pp.567-579
28/03/2019
Metrics
19 Record Views
UN Sustainable Development Goals (SDGs)
This output has contributed to the advancement of the following goals:
Source: InCites
Abstract
Tropical islands can facilitate surface ocean biological productivity by enhancing the supply of nitrogen to the euphotic zone. Yet in the world's most oligotrophic oceanic region, the South Pacific Subtropical Gyre (SPSG), this “island mass effect” appears diminished. If this is the case, where did island coral reefs in the SPSG get their nitrogen from, and has this changed over time? Here we use coral skeleton isotopes (δ15N and δ18O) and element/Ca ratios to identify the sources of nitrogen to a late Pleistocene coral reef in the SPSG (Cook Islands); we then compare these results to modern corals in the same region. The supply of nitrogen to the late Pleistocene reef appears dominated by upwelling of subsurface nitrogen during cool dry events, supplemented with nitrogen from island‐induced N2 fixation (27 ± 3%) during warm wet periods. For the modern corals, N2 fixation supplies nitrogen to the island reefs during cool dry periods with groundwater providing nitrogen during wet periods. We propose that the subsurface supply of nitrogen to the modern reefs has declined as a result of reduced upwelling but this supply has been replaced with increasing nitrogen discharge from groundwater and an increase in island‐induced N2 fixation.
Key Points
Coral skeleton isotopes are used to identify the sources of nitrogen to a late Pleistocene coral reef
The supply of nitrogen to the late Pleistocene reef appears dominated by upwelling of subsurface nitrogen
For modern corals there has been a switch to groundwater nitrogen and N2 fixation as the major sources
Details
- Title
- Has Nitrogen Supply to Coral Reefs in the South Pacific Ocean Changed Over the Past 50 Thousand Years?
- Creators
- Dirk V Erler (Author) - Southern Cross UniversityBenjamin O Shepherd (Author) - Southern Cross UniversityBraddock K Linsley (Author) - Columbia UniversityLuke D Nothdurft (Author) - Queensland University of TechnologyQuan Hua (Author) - Australian Nuclear Science and Technology OrganisationJanice M Lough (Author) - ARC Centre of Excellence for Coral Reef Studies
- Publication Details
- Paleoceanography and Paleoclimatology, Vol.34(4), pp.567-579
- Publisher
- Wiley-Blackwell Publishing, Inc.
- Number of pages
- 13
- Grant note
- Australian Pacific Science Foundation (APSF14_5) Australian Institute of Nuclear Science and Engineering (AINSE) (ALNGRA 15031) Australian Government for the Centre for Accelerator Science
- Identifiers
- 991012925098302368
- Copyright
- © 2019. American Geophysical Union. All Rights Reserved.
- Academic Unit
- Centre for Coastal Biogeochemistry; National Centre for Flood Research; Faculty of Science and Engineering; Science
- Language
- English
- Resource Type
- Journal article