DOI: 10.5061/dryad.tq381
title: Data from: Alongshore variation in barnacle populations is determined by surfzone hydrodynamics

description: Larvae in the coastal ocean are transported toward shore by a variety of
 mechanisms. Crossing the surf zone is the last step in a shoreward
 migration and surf zones may act as semipermeable barriers altering
 delivery of larvae to the shore. We related variation in the structure of
 intertidal barnacle populations to surfzone width (surfzone hydrodynamics
 proxy), wave height, alongshore wind stress (upwelling proxy), solar
 radiation, and latitude at 40 rocky intertidal sites from San Diego,
 California to the Olympic Peninsula, Washington. We measured daily
 settlement and weekly recruitment of barnacles at selected sites and
 related these measures to surfzone width. Chthamalus density varied
 inversely with that of Balanus, and the density of Balanus and new
 recruits was negatively related to solar radiation. Across the region,
 long-term mean wave height and an indicator of upwelling intensity and
 frequency did not explain variation in Balanus or new-recruit densities.
 Balanus and new-recruit densities, daily settlement and weekly recruitment
 were up to three orders of magnitude higher at sites with wide (&gt;
 50 m), more dissipative surf zones with bathymetric rip currents than at
 sites with narrow (&lt; 50 m) more reflective surf zones. Thirty to
 50% of the variability in Balanus and new-recruit densities was explained
 by surfzone width. We sampled a subset of sites &lt; 5 km apart where
 coastal hydrodynamics such as upwelling should be very similar. At paired
 sites with similar surfzone widths, Balanus densities were not different.
 If surfzone widths at paired sites were dissimilar, Balanus densities,
 daily settlement and weekly recruitment were significantly higher at sites
 with the wider more dissipative surf zone. The primary drivers of surfzone
 hydrodynamics are the wave climate and the slope of the shore and these
 persist over time, and therefore site-specific stability in surfzone
 hydrodynamics should result in stable barnacle population characteristics.
 Variations in surfzone hydrodynamics appear to play a fundamental role in
 regulating barnacle populations along the open coast, which in turn may
 have consequences for the entire intertidal community.
description: Shanks et al. Ecol
 MonoData are a combination
 of field-collected data on barnacle populations at stations from San
 Diego, California to La Push, Washington. Stations names are in column A
 and they were cataloged (column B) as either rocky shores (1, continuous
 rocks intertidal for at least 50 m) or rocks within beaches (2, rocky
 shore &lt;50 m). The latitude and longitude (columns D and E) are precise
 locations using the ‘place’ tool in Google Earth. Columns F and G are
 alongshore wind stress (a proxy for upwelling/downwelling) and average
 wave height calculated for each station latitude. See Shanks et al (in
 press) for descriptions of the methods. Daily solar radiation (column H)
 is from the National Solar Radiation Data Base
 (http://rredc.nrel.gov/solar/old_data/nsrdb/). Average surfzone width
 (Column I) was determined from Google Earth images (See Shanks et al, in
 press for methods). Intertidal width and beach angle (columns J and K)
 were measured in the field at the time the stations were sampled and
 methods are described in Shanks et al. (in press). Barnacle data (columns
 L-W) are from photographs taken in the field at each sample site. ImageJ
 was used to analyze the photographs and methods are describe in Shanks et
 al. (in press).Daily Barncle settlement
 in 2011Daily barnacle
 settlement data for 2011. Data are daily settlement to bare rock surface
 quadrats. There were three replicates at Pack Trail, Bastendorff, Carmel
 North, and Carmel South. Blanks in the matrix indicate missing data. See
 Shanks et al. (in press) for a description of the methods and the latitude
 and longitude of the sample sites.Shanks et al. Eco Mono File 2
 daily settlement.xlsxWeekly barnacle
 recruitment in 2010Weekly barnacle
 recruitment data to bare rock quadrats in 2010. The latitude and longitude
 of each sample site is in Shanks et al. (in press) as well as a detailed
 description of the sample methods.Shanks et al. Eco Mono File 3
 weekly recruitment.xlsxBarnacle Size frequency
 data for 26 samples stationsSize frequency
 distributions (percent) for barnacles in a latitudinal study of
 populations along the west coast of North America. Size bins are in mm.
 Station locations can be found in Shanks et al. (in
 press).Shanks et al. Eco Mono File 3
 size freq distributions.xlsx