Dataset: Carbon and nitrogen stable isotope measurements of gelatinous zooplankton and larval fish in the Northern California Current

Gelatinous zooplankton and larval fish were collected using MOCNESS (Multiple Opening/Closing Net and Environmental Sensing System) tows in 25-meter (m) depth increments in the upper 100m of the water column (nets: 1 square meter (m²) with 333-micrometer (µm) mesh and 4 m² with 1000 µm mesh). Organisms in each tow were grouped by lowest visually identifiable taxon. Maximum and minimum lengths of individuals in each group were measured with a ruler and the volume of each sample of grouped individuals was measured by displacement. Samples were frozen at -20 degrees Celsius (°C) prior to preparation for stable isotope analysis.

Wet weight of each grouped sample was measured upon thawing the sample. Samples were dried at 60°C, then dry weights were measured. Samples were then crushed and homogenized using an agate mortar and pestle. Stable isotope compositions and carbon and nitrogen contents were measured by elemental analyzer-isotope ratio mass spectrometry (EA-IRMS) at the UC Davis Stable Isotope Facility. Ash-free dry weights were determined by weighing samples before and after combusting dried samples at 500°C.