Data for: Latitudinal variation in seasonal cycle mediates population differences in barnacle reproduction phenology

The timing of life history events around reproduction and early development is critical in population dynamics, and it can determine recruitment success, species dispersal, and population connectivity. In ectotherms, as well as in plants and fungi, phenology is mediated by the nonlinear effects of temperature on physiology and development, meaning that spatiotemporal variation in temperature can exert powerful controls on the timing of local reproduction and recruitment. Here, we examine reproduction phenology (fertilization of embryos, duration of embryonic development during brooding, and larval release) of the intertidal acorn barnacle Semibalanus balanoides in 2002-04 and in 2019-24 at up to 8 sites along a steep temperature gradient in the northwest Atlantic Ocean. At each site and year, we assessed how phenology varied with intertidal temperature, estimated with a hybrid atmosphere-ocean data assimilation model. Although within-site reproduction was delayed due to interannual and ..., The data package contains two folders. The first folder data/ contains: (i) weekly barnacle reproductive proportion data, (ii) hourly temperature logger data from Newagen, Maine, 2003, (iii) filtered intertidal temperatures, and (iv) site metadata. The second folder NOAH_IntertidalModel/ contains: (v) North American Regional Reanalysis (NARR) example data for the year 2000, (vi) OSTIA reprocessed SST example data for the year 2000, subset for Northeast US/Canada coast, and (vii) the suggested directory structure for using XTide, along with the header file for the version of libtcd (a prerequisite software for XTide) used in this study.
(i) Weekly barnacle reproductive proportions were measured at up to eight sites along a steep temperature gradient in the northwest Atlantic during two historical and five modern years.
(ii) We include hourly temperature logger (Onset Corp.) data for Newagen, Maine, collected in 2003 for intertidal and subtidal habitat, as well as logger data for Halifax,..., , # Data for: Latitudinal variation in seasonal cycle mediates population differences in barnacle reproduction phenology

[https://doi.org/10.5061/dryad.gxd2547wk](https://doi.org/10.5061/dryad.gxd2547wk)

## Description of the data and file structure

#### File: Sbal_phenology_data_Mar2026.zip

**Description:** 
**The first folder,** **data/,** contains weekly *Semibalanus balanoides* barnacle reproductive proportion data; 2003 hourly temperature logger data for Newagen, Maine, USA; filtered intertidal temperatures; site metadata; and example data files for NARR and OSTIA data products. Missing values are included either as blank cells or \"NA\".

DataLog .csv files contain up to 5 columns: collection date, site name, and % of sampled adults that were not brooding (perc_nonrep), that contained early-stage embryos (perc_early), or that contained late-stage embryos (perc_late). Some files also include a notes column.

site_locations.csv file contains site metadata, along with parameters used..., ,