Effects of elevated seawater pH and total alkalinity following dosing of sodium hydroxide in <em>Calanus finmarchicus</em>

This dataset contains measurements of survival, escape performance, and oxygen consumption for the copepod Calanus finmarchicus following short-term exposure to NaOH-dosed seawater intended to simulate transient exposure during ocean alkalinity enhancement (OAE) field deployments. Late-stage copepodites (C4–C5; “juveniles”) and adult females (C6) were exposed to two elevated pH/total alkalinity (TA) conditions: pH 10.5 (~5,000 µmol kg⁻¹ TA) for 1, 5, or 10 minutes and pH 9.0 (~3,150 µmol kg⁻¹ TA) for 1, 15, or 30 minutes, alongside an ambient control: pH 8.0 (2,150 µmol kg⁻¹ TA). Survival was recorded immediately after exposure and during subsequent monitoring through 72 hours post-exosure (hpe). Escape response (ability to initiate an escape jump) was assessed immediately post-exposure and at follow time points at 24 and 72 hpe. Routine metabolic rate was quantified via microplate respirometry as oxygen consumption following a 10-minute exposure to pH 10.5, measured immediately after e..., , # Data from: Effects of elevated seawater pH and total alkalinity following dosing of sodium hydroxide in *Calanus finmarchicus* Dataset DOI: [10.5061/dryad.s7h44j1p1](https://doi.org/10.5061/dryad.s7h44j1p1) ## Description of the data and file structure We collected these data to quantify acute biological responses of the copepod *Calanus finmarchicus* to short, high-intensity pH and total alkalinity (TA) perturbations expected during ocean alkalinity enhancement (OAE) plume exposure. Late-stage copepodites (C4–C5; juveniles) and adult females (C6) were exposed to NaOH-dosed seawater at pH 10.5 (~5,000 µmol kg⁻¹ TA) for 1, 5, or 10 minutes and at pH 9.0 (~3,150 µmol kg⁻¹ TA) for 1, 15, or 30 minutes, with an ambient control (pH 8.0; ~2,150 µmol kg⁻¹ TA). Following exposure, individuals were assessed for immediate mortality and then monitored for survival through 72 hours post-exposure (hpe). Escape performance (ability to initiate an escape response) was measured immediately after e..., ,