Fish Carbonates - Their dissolution potential under elevated hydrostatic pressure

Lead Research Organisation: University of Exeter
Department Name: Biosciences

Abstract

A major component of the marine-atmospheric carbon cycle is the precipitation and dissolution of calcium carbonate in seawater. Calcium carbonate is the mineral that makes up rocks such as limestone and chalk. Detailed knowledge of this component is important to our understanding of the global carbon cycle, and to the Earth system as a whole. This proposal aims to explore recent findings that represent a fundamental and previously unexpected change to our understanding of the marine inorganic carbon budget. Large amounts of calcium carbonate are produced in the global oceans by marine plankton and, specifically, by microscopic organisms such as coccolithophores and foraminifera. However, recent research by the PI has highlighted the significant additional contribution to oceanic carbonate production by marine bony fish. These animals ingest sea water and are now known to also precipitate calcium carbonate within their guts and excrete these at very high rates as part of their normal functioning in seawater. This previously unrecognised source of marine carbonate is significant in its own right but, when combined with new estimates of global fish biomass, it is clear that it makes a major contribution to carbonate production on a global scale. Furthermore, due to their rather unusually high content of magnesium, these fish carbonates are predicted to be more soluble (i.e. more likely to dissolve whilst sinking) than the better know forms of calcium carbonate produced by other marine calcifying organisms. The issue of solubility is important to ocean chemistry, as carbonates that dissolve rapidly upon sinking, in the upper 500-1000 m of the ocean, will restore the alkalinity and buffer capacity of surface waters, which in turn enhances the ocean's capacity to absorb further CO2 from the atmosphere. Theoretically, the little we know about the chemistry of fish carbonates suggests they will be one of the fastest dissolving forms of this mineral. This proposal will be the first ever attempt to actually measure the influence of sinking (i.e. hydrostatic pressure) on the dissolving potential of carbonates derived from fish. This would help explain a mystery of ocean chemistry that has puzzled oceanographers for decades, i.e. the unexpectedly increase in alkalinity in the first 1000 m of depth in the Atlantic and Pacific oceans. In addition, the laboratory setting allows for the incorporation of the effect of fluid flow on the aggregates, ensuring a more realistic simulation of sinking, and consequently more accurate simulation results.

Publications

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Roberts CM (2017) Marine reserves can mitigate and promote adaptation to climate change. in Proceedings of the National Academy of Sciences of the United States of America

 
Description We have found that elevated CO2 (predicted for the future ocean) can increase gut calcium carbonate production by marine fish. However, the chemistry of these carbonates is not affected in any major way. So fish are likely to play an even great role in regulating the chemistry of the surface ocean in the future.
Exploitation Route The outputs will feed into the data that we will be provide to the Met Office from the linked standard NERC grant (NE/H01004/1), and so will be used to help revise their global marine carbon cycle models.
Sectors Energy,Environment

 
Description COST Short Term Scientific Mission (STSM)
Amount € 1,660 (EUR)
Funding ID COST-STSM-FA1004-11324 
Organisation European Cooperation in Science and Technology (COST) 
Sector Public
Country European Union (EU)
Start 08/2012 
End 08/2012
 
Description NERC Standard grant
Amount £461,688 (GBP)
Funding ID NE/K003143/1 
Organisation Natural Environment Research Council 
Sector Public
Country United Kingdom
Start 08/2013 
End 07/2017
 
Description Mesopelagic fish carbonates (Atlantic) - Institute of Sea Fisheries, Hamburg 
Organisation University of Hamburg
Department Institute for Hydrobiology and Fisheries Science
Country Germany 
Sector Academic/University 
PI Contribution Samples of the gut contents of mesopelagic fish from the mid Atlantic (see below) were obtained from freshly thawed fish at Exeter. Otoliths were also be sampled together with organic tissue (white muscle) to provide comparison of the carbonate chemistry within otoliths and intestinal carbonates, and to compare stable isotopes signatures of C and O in future work. Dr. Erin Reardon processed the samples for analysis of the carbonate crystal structure and elemental composition (using ion chromatography, SEM and TEM with EDS analysis, and also XRD/FTIR for mineralogy). This was funded through an Exeter University Strategic Development Fund (SDF) grant.
Collaborator Contribution Through collaboration with Stephanie Czudaj, mesopelagic fish were sampled at a wide range of depths (surface to 1000 m deep) in the mid Atlantic by collaborators from Gran Canara during a multi-national research cruise project based in the Atlantic - "Migrants and Active Flux In the Atlantic ocean" in the early part of 2015. Samples were frozen to preserve gut carbonate content and then shipped on dry ice to Exeter once the ship returned to port.
Impact Data still being analysed. No outputs yet, but a NERC grant (Large or Standard) is anticipated. Also, this pilot data has contributed towards Rod Wilson being a joint applicant PI in a NERC Research Programme ("The Changing Arctic Ocean: implication for marine biology and biogeochemistry") grant led by Prof. Andrew Brierley (St. Andrews) on "Foodweb consequences In a changinG ARctic Ocean for plankton, predators and fisheries (FIGARO)". The total value of this grant is estimated to be £2.1M and the deadline for submission is mid March 2016.
Start Year 2014
 
Description Mesopelagic fish carbonates (Atlantic) - Universidad de Las Palmas de Gran Canaria and Institute of Sea Fisheries Hamburg 
Organisation University of Las Palmas de Gran Canaria
Department Institute of Oceanography
Country Spain 
Sector Academic/University 
PI Contribution Samples of the gut contents of mesopelagic fish from the mid Atlantic (see below) were obtained from freshly thawed fish at Exeter. Otoliths were also be sampled together with organic tissue (white muscle) to provide comparison of the carbonate chemistry within otoliths and intestinal carbonates, and to compare stable isotopes signatures of C and O in future work. Dr. Erin Reardon processed the samples for analysis of the carbonate crystal structure and elemental composition (using ion chromatography, SEM and TEM with EDS analysis, and also XRD/FTIR for mineralogy). This was funded through an Exeter University Strategic Development Fund (SDF) grant.
Collaborator Contribution Through collaboration with Prof. Santiago Hernández León (Instituto de Oceanografía, Universidad de Las Palmas de Gran Canaria), mesopelagic fish were sampled at a wide range of depths (surface to 1000 m deep) in the mid Atlantic by collaborators from Gran Canara during a multi-national research cruise project based in the Atlantic - "Migrants and Active Flux In the Atlantic ocean" in the early part of 2015. Samples were frozen to preserve gut carbonate content and then shipped on dry ice to Exeter once the ship returned to port.
Impact Data still being analysed. No outputs yet, but a NERC grant (Large or Standard) is anticipated. Also, this pilot data has contributed towards Rod Wilson being a joint applicant PI in a NERC Research Programme ("The Changing Arctic Ocean: implication for marine biology and biogeochemistry") grant led by Prof. Andrew Brierley (St. Andrews) on "Foodweb consequences In a changinG ARctic Ocean for plankton, predators and fisheries (FIGARO)". The total value of this grant is estimated to be £2.1M and the deadline for submission is mid March 2016.
Start Year 2014
 
Description Mesopelagic fish carbonates (Red Sea) - KAUST University, Saudi Arabia 
Organisation King Abdullah University of Science and Technology (KAUST)
Country Saudi Arabia 
Sector Academic/University 
PI Contribution Samples of the gut contents of mesopelagic fish from the Red Sea (see below) were obtained from freshly thawed fish at Exeter. Otoliths were also be sampled together with organic tissue (white muscle) to provide comparison of the carbonate chemistry within otoliths and intestinal carbonates, and to compare stable isotopes signatures of C and O in future work. Dr. Erin Reardon processed the samples for analysis of the carbonate crystal structure and elemental composition (using ion chromatography, SEM and TEM with EDS analysis, and also XRD/FTIR for mineralogy). This was funded through an Exeter University Strategic Development Fund (SDF) grant.
Collaborator Contribution Through collaboration with Drs. Fanny Debusserolles, Xabier Irigoien and Anders Rostad at KAUST, mesopelagic fish were sampled at maximum and minimum depths in the Red Sea by collaborators at KAUST using their ship facility. Samples were frozen to preserve gut carbonate content and then shipped on dry ice to Exeter.
Impact Data still being analysed. No outputs yet, but a NERC grant (Large or Standard) is anticipated. Also, this pilot data has contributed towards Rod Wilson being a joint applicant PI in a NERC Research Programme ("The Changing Arctic Ocean: implication for marine biology and biogeochemistry") grant led by Prof. Andrew Brierley (St. Andrews) on "Foodweb consequences In a changinG ARctic Ocean for plankton, predators and fisheries (FIGARO)". The total value of this grant is estimated to be £2.1M and the deadline for submission is mid March 2016.
Start Year 2014