Dataset: Santa Monica Bay Nutrients

Blooms were targeted in Santa Monica Bay during spring 2018 and 2019 using local meteorological information to anticipate coastal upwelling events (Figure S1, Ollison et al., 2022). Sampling from the Santa Monica Pier (SMP) was conducted daily at 0900 (PST/PDT) from the same location and orientation on the SMP from the 16^th through the 30^th in April 2018 (15 days), and in 2019 from the 13^th April through 6^th May (22 days; no sample was collected on the 14^th April 2019). Sampling periods are henceforth referred to as 2018 and 2019, respectively.

An RBR Concerto (https://rbr-global.com) was deployed in surface water for 15 minutes at the time of each sample collection to obtain temperature, conductivity, chlorophyll a fluorescence, and dissolved oxygen concentrations (See "Related Dataset" section for CTD data). A 20 µm mesh plankton net was drift towed from the pier (15 min), and samples were examined via light microscopy to identify the dominant planktonic taxa and their relative abundances.

Surface water for 18S rRNA sequencing (see Related Datasets section), nutrient analyses, cell counts, extracted chlorophyll concentrations, and domoic acid concentrations was collected via bucket toss from the pier; an extended funnel was used to gently fill a single acid-washed-3x-rinsed 20 L carboy per established lab protocol (https://www.protocols.io/view/sample-collection-from-the-field-for-downstream-mo-hisb4ee). The carboy was protected from the light and immediately transported approximately 300 meters to the Heal the Bay Aquarium located at the SMP for sample processing.

Samples for nitrite + nitrate and phosphate were measured from 0.02 μm filtered seawater via flow injection analysis on a Quickchem 8500 at the Marine Science Institute Analytical Lab, UCSB (See supplemental files for metadata about these analyses).