Supplementary Table 1: Average Hydrographic, Date of Collection (Date) and Net Data For

Supplementary Table 1:Average hydrographic, date of collection (date) and net data for each day and night net tows (tow identification, ID) at the Costa Rica Dome (CRD) and Tehuantepec Bowl (TB) during 2007 and 2008. Minimum and maximum pressures are recorded in decibars (dB) and served as a proxy for depth(1 dB ≈ 1 m). Volume of water filtered through each net was measured in m3 (V.f.). Net depths sometimes varied between years or stations, so depths were grouped into categories for statistical analysis (depth cat.). Temperature (ºC), salinity (Psu), and O2 (µmol kg-1) are the average value over the net interval. Missing MOCNESS data were estimated using CTD casts made at the same station during the same year; these values are reported in bold print. Depth categories are: (1) 0-50 m (2) 50-150 m (3) 150-300 and (4) 350-400 (see methods). MOCNESS physical data were processed by R. Williams, D.Outram, and K. Wishner.

Supplementary Table 2: Abundance (# individuals 1000 m-3) of pteropods collected by the MOCNESS from the Tehuantepec Bowl (TB) and Costa Rica Dome (CRD) during the day and night in 2007 and 2008. Minimum and maximum pressures are recorded in decibars (dB) and served as a proxy for depth (1 dB ≈ 1 m). Cavolinia uncinata was never reported in the MOCNESS, but was obtained exclusively from SCUBA dives from 0-30 m during both the day and night at the CRD in 2008.