Ocean warming, acidification, and chemistry of the South Pacific & North Atlantic: a brachiopod investigation
Bibliographic record
Abstract
Global CO2 emissions drive ocean warming and acidification. Local-level ocean data is limited, so natural archives like brachiopods are used to understand past oceanic conditions. Brachiopod shells record seawater temperatures, chemistry, and acidity. This thesis uses brachiopods from Paterson Inlet, New Zealand (1900–2021), and the Bay of Fundy, Canada (1970–2009) to track past oceanographic conditions and fill local data gaps. Global oceans recorded a decrease in δ13C DIC values of 0.50 ‰ (~1900-1985), comparable to the δ13CB value of -0.48‰ for Paterson Inlet (1900-2014), a rate of -0.04‰ per decade. The Bay of Fundy brachiopods recorded decreasing δ13CB values by 0.25‰ per decade (1970-2009). Ocean acidification is driven by the mixing of atmospheric CO2, and anthropogenic emissions are enriched in 12C, suggesting a link between pH and δ13CB values. The brachiopod shells δ18OB and Li/Ca levels record ambient seawater temperatures. In Paterson Inlet, seawater temperatures calculated with Li/Ca and δ18O values suggest cooling (ΔT = -0.035℃ per decade; 1900-2014). Temperatures calculated with δ18OB values for the Bay of Fundy indicate cooling (-0.25°C per decade; 1970-2009). Bay of Fundy seawater has recorded decreasing δ18OSW values by -0.16 ‰ per decade (1970-2022), reflecting potential arctic meltwater influx, cooling the seawater. The burning of coal drives CO2 emissions. Coal emissions contain various heavy metals, including selenium. Brachiopods record an increase in selenium concentrations of +6.14 mmol (1926-1960). Subsequently, in 1960-1980, selenium content decreased by -7.54 mmol but has since been increasing with a slightly upward trend of +1.78 mmol (2009-2021). Similar trends are observed in the brachiopod’s lanthanum content, another element found in coal, suggesting that brachiopod shell chemistry contains a record of coal burning. Archives such as brachiopods are an important source of information regarding the changing oceans. Although systems exist to monitor oceanic conditions, they cannot trace small-scaled effects. Brachiopods from Paterson Inlet and the Bay of Fundy record local changes in seawater conditions over the past 120 years. Some trends, such as δ13CB values, correspond with global ones, while others, such as temperatures, are not, reflecting the complex interaction of climate and weather/oceanographic changes on a local scale.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.001 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".