Western and northeast subarctic study settings
The 40°N–66°N band is a broad subarctic geographic reference, not an HNLC boundary or project area. SEEDS-I, SEEDS-II and SERIES produced different biological and particle responses. Season, silicate, grazing and the permanent thermocline separate a bloom from durable isolation.
Regional carbon pathway
Named field studies separate observed responses from unresolved atmospheric removal and durability.
SERIES: A northeast-Pacific bloom with silica export at 50–125 m, later POC export, strong grazing and bacterial remineralisation.
SEEDS I / II: Contrasting western-Pacific responses; no significant increase in 200 m POC flux was detected during the reported SEEDS I observation period.
SERIES followed a northeast-Pacific treatment patch through bloom and decline across a seasonally mixed upper ocean.Evidence: Boyd et al. (2004)
A traced treatment patch, reference observations and repeated sampling separated biological response from dilution, mixing and seasonal change.Evidence: Boyd et al. (2004)
SERIES included Pseudo-nitzschia among dominant bloom taxa; grazing and bacterial activity shaped the subsequent carbon pathway.Evidence: Boyd et al. (2004)
Sinking diatoms increased silica export at 50–125 m before increased POC export. More than half of the mixed-layer POC deficit was attributed to bacterial remineralisation and mesozooplankton grazing.Evidence: Boyd et al. (2004)
Strong upper-ocean attenuation limited transfer below the permanent thermocline in the reported window; remineralised carbon remains subject to water-mass circulation and later ventilation.Evidence: Buesseler et al. (2024)
Treatment and reference time series require matched particle flux, carbonate chemistry, grazing, bacterial activity and winter-depth observations.Evidence: Buesseler et al. (2024)
SEEDS-I and SEEDS-II were separate western subarctic Pacific experiments with different initial communities, food webs and physical conditions.Evidence: Tsuda et al. (2003) · Saito et al. (SEEDS-II)
Each SEEDS cohort requires its own treatment, reference and observation window; the experiments do not form one interchangeable response.Evidence: Tsuda et al. (2003)
SEEDS-I shifted toward centric Chaetoceros debilis; SEEDS-II had a weaker response shaped by small cells and grazing.Evidence: Tsuda et al. (2003) · Saito et al. (SEEDS-II)
During the reported SEEDS-I observation period, drifting traps detected no significant increase in POC flux at 200 m. This result is distinct from SEEDS-II grazing observations.Evidence: Aono et al. (2005)
Enhanced deep flux was not observed in the SEEDS-I 200 m trap record; grazing, remineralisation, seasonal re-entrainment and circulation remain separate fate pathways.Evidence: Buesseler et al. (2024)
Separate SEEDS-I and SEEDS-II treatment/reference records require matched taxonomy, grazing, particle flux, carbonate chemistry and physical transport.Evidence: Buesseler et al. (2024)
SEEDS-I shifted toward Chaetoceros debilis; SERIES included Pseudo-nitzschia among dominant bloom taxa. SEEDS-II had a weaker response shaped by small cells and grazing.
Western and northeast subarctic experiments cannot be collapsed into one regional response; their communities, seasons and physical settings differ.
SERIES increased export near the mixed-layer base, while transfer below the permanent thermocline was inefficient in the reported window.
Not quantified
No field-derived regional GtCO₂/yr estimate.
Buesseler et al. (2024)
Seasonal ship and sensor coverage, particle-depth and thermocline observations, taxonomy, toxin measurements and repeated food-web sampling.
02 · evidence pathway
Field observations, model outputs and unresolved questions answer different parts of the pathway. Together, the records describe study-specific responses; net atmospheric removal and legal status remain separate questions.
Primary evidence: Tsuda et al. (2003) · Boyd et al. (2004) · Tsuda et al. (2007) · Trick et al. (2010)
SEEDS experiments took place in the western subarctic Pacific; SERIES took place in the northeast. Seasonal and physical context matters.
SEEDS-I and SERIES selected different diatom communities, showing that 'algae response' is not one outcome.
SEEDS-II produced a smaller response shaped by small cells and grazing.
SERIES observations found increased export near the mixed-layer base but limited transfer below the permanent thermocline during the study.
Pseudo-nitzschia and domoic acid are monitoring targets. Evidence of a credible hazard does not imply the same response everywhere.
Biological response
Cell size, silica demand, aggregation, grazing, toxins and food-web pathways influence whether fixed carbon is recycled or transported.
SEEDS-I shifted toward Chaetoceros debilis; SERIES included Pseudo-nitzschia among dominant bloom taxa. SEEDS-II had a weaker response shaped by small cells and grazing.
Taxonomy and chlorophyll alone do not determine grazing, aggregation, dissolved-carbon release, toxin response or later remineralisation.
Taxonomy, size structure, primary production, grazing, particle size, toxins, oxygen, pH, trace gases and food-web indicators form a matched time series.
Carbon pathway
SERIES increased export near the mixed-layer base, while transfer below the permanent thermocline was inefficient in the reported window.
Western and northeast subarctic experiments cannot be collapsed into one regional response; their communities, seasons and physical settings differ.
Open the five-breakpoint explorer →Observation design
Matched physical, biological, chemical and ecological observations separate intervention effects from background variability across time and space.
Taxonomy, grazing, toxins, particle flux, remineralisation and water-mass exchange across the permanent thermocline.
Explore instruments and limits →Seasonal ship and sensor coverage, particle-depth and thermocline observations, taxonomy, toxin measurements and repeated food-web sampling.
Operational costs depend on vessel time, instrumentation, sampling design and follow-up; no regional cost estimate is available here.
Featured evidence contexts
These records connect regional mechanisms to specific experiments, observatories and natural analogues without ranking the settings.
What fraction of bloom carbon passes below winter ventilation depth instead of being grazed, respired or diluted?
Subarctic North PacificRead the evidence context →03Repeat mesoscale field experimentsWhich initial ecological and physical measurements explain a SEEDS-like bloom versus a SEEDS-II-like grazing response?
Subarctic North PacificRead the evidence context →Governance context
High-seas experiments, protected island systems, EEZ research locations and disputed maritime spaces have distinct institutional and legal contexts.
Coordinates, water-column and downstream domains, vessel flag, ports, material, research purpose and potential effects shape the applicable routes.
Authority can depend on the exact activity, location, vessel, operator, material, duration, effects and applicable law.
Open governance & legal context →
