Daily air and water temperatures, monthly mean wave heights, and monthly tidal extremes from central Oregon to southern California

Abstract

Latitudinal variation in intertidal conditionsTemperature Logger Data AnalysisTo characterize the temperature regime at each site (see Sites dataset), we used existing temperature loggers deployed by the PISCO and MARINe research programs during 2016-2018. Most sites (n = 25) had at least one logger deployed during the study but several sites (n=8) did not, so we used the nearest site with a logger, with a maximum distance of 44.8 km away from a site. Temperature loggers (HOBO TidBit v2 by Onset) were deployed at fixed locations inside steel mesh cages, set to record every 15 mins, and swapped every ~6-12 months. Once loggers were collected, we assigned the tidal levels for each site and time stamp using Xtide software (https://flaterco.com/xtide/files.html) and the nearest harmonic tidal station (see Environmental Stations). We included logger temperatures for 2016 – 2018 since not all sites had loggers deployed continuously in 2018 alone. We graphed the temperature and the tide heights for each logger, and used this to visually estimate the shore level of the logger to the nearest 0.5 ft (air temperatures have clearly higher variance than water temperatures). We assigned any tide height higher than the logger height as “water” and any tide height lower than the logger height as “air”. We calculated the daily average mean and maximum air and water temperatures at each site, then graphed the monthly means with latitude to visualize latitudinal trends. We also calculated the average daily mean and maximum water temperature from 2016-2018. On wavy days, temperatures assigned as air temperatures probably intermittently submerged. However, we are more interested in air temperature stress than average air temperature, so our focal air temperature metric was maximum daily air temperature, which likely occurred during the lowest tides when waves were not washing over the loggers.Tidal Extremes, Tidal Amplitude, and Significant Wave HeightTo broadly characterize tidal levels and wave exposure trends that may influence the latitudinal and vertical ranges of our focal species, we queried daily environmental data during 2018 from offshore NOAA offshore oceanographic buoys for waves (https://www.ndbc.noaa.gov/obs.shtml) and onshore tidal stations for tides (https://tidesandcurrents.noaa.gov/stations.html?type=Water+Level+Reports) closest to each of our sites (see Environmental Stations). We calculated and graphed the average daily and then monthly mean significant wave height (i.e., highest ⅓ of waves) from each oceanographic buoy and the highest and lowest monthly tidal extremes for each onshore tidal station.</p