A new study by the GEOMAR Helmholtz Centre for Ocean Research Kiel examined the effect of moderate ocean alkalinity enhancement (OAE) on the food web and ecosystem in the oceanic water, observing that it had minimal impact on the zooplankton.
The team of scientists from Prof. Ulf Riebesell´s group at GEOMAR Helmholtz Centre for Ocean Research Kiel published their findings in the Science Advances journal, reflecting on the effort completed as part of the European OceanNETs project.
Due to its natural ability to absorb carbon dioxide emissions, the ocean is central to many decarbonization technologies focused on mitigating climate change.
Ocean alkalinity enhancement is one such technology that entails the release of ground rock, or its dissolution products, directly into the seawater, where it boosts the water alkalinity, increasing its capacity for CO2 absorption.
In an attempt to learn more about the impact of OAE, the researchers set off to explore in the waters off Gran Canaria, where they applied a method called CO₂-equilibrated Ocean Alkalinity Enhancement, performed with moderate perturbations to seawater chemistry.
The team released alkalized, carbon-saturated water into the marine environment, leveraging large test tubes called KOSMOS mesocosms that are lowered directly into the seawater, isolating eight cubic meters of the water column.
The CO2-equilibrated OAE was modified with sodium carbonate and bicarbonate to achieve varying concentrations that range from no alkalinity increase to a double natural alkalinity surge.
For a period of 33 days, the team monitored the reactions of the zooplankton, assessing responses from biomass and production to diversity and fatty acids.
Relevant: New Study Proves Safety And Effectiveness Of Ocean Alkalinity Enhancement
The findings show that the zooplankton tolerated the moderate chemical changes introduced by the CO2-equilibrated OAE, remaining stable even though during the experiment the nutritional value of the matter on which zooplankton can feed potentially deteriorated.
While these findings signal hope for OAE as a safe carbon removal method, researcher Nicolás Sánchez, PhD, clarifies that this doesn’t say anything about how this decarbonization method might affect other marine environments or about the safety of other, technically more feasible forms of OAE that cause more substantial changes to seawater chemistry.
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