DOI: 10.5061/dryad.jwstqjq6k
title: Data from: Long-term mechanistic hindcasts predict the structure of experimentally-warmed intertidal communities

description: Increases in global temperatures are expected to have dramatic effects on
 the abundance and distribution of species in the coming years. Intertidal
 organisms, which already experience temperatures at or beyond their
 thermal limits, provide a model system in which to investigate these
 effects. We took advantage of a previous study in which experimental
 plates were deployed in the intertidal zone and passively warmed for 12
 years to a daily maximum temperature on average 2.7°C higher than control
 plots on the adjacent bedrock. We compared the composition of the
 biological communities on each experimental plate with its neighboring
 bedrock control. Plate communities showed decreased richness of taxa and
 percent cover of filamentous algae, mussels and mobile grazers relative to
 bedrock, and increased percent cover of biofilm. We then used short-term
 time-series measurements of plate and bedrock temperatures and a
 mechanistic heat-budget model to hindcast those temperatures back 12
 years. Greater differences in long-term average temperature between the
 experimental plates and bedrock controls were correlated with lower
 similarity in community composition. Additionally, years with higher
 average differences between plate and bedrock temperatures were more
 predictive of current compositional similarity between plate and bedrock
 communities, even though they occurred farther in the past than did more
 recent, but cooler, years. We conclude that current intertidal communities
 reflect their long-term, rather than short-term, thermal histories.
 Mechanistic heat-budget models based on short-term measurements can
 provide this valuable, long-term information.
description: Heat-budget model output is contained in the .txt files (except
 Data.txt). The filename indicates whether the hindcasted temperature
 record is associated with a plate (Plate) or bedrock (Rock) sample, the
 sample number, whether the record has been summarized daily (maximum daily
 temperature or daily degree minutes) or yearly (significant annual
 temperature or significant annual degree minutes), and whether the record
 was produced by a model optimized to produce the most accurate maximum
 temperatures (MAX) or degree minutes (DMS). Inside each file, the first
 column contains maximum temperature data (maximum daily temperature or
 significant annual temperature) and the second column contains degree
 minutes data (daily degree minutes or significant annual degree
 minutes). Data.txt contains the raw temperature data
 taken from each plate and bedrock sample in the field between August and
 October 2013. The first column is always 101. The second, third and forth
 columns contain the year, day of year and time data. The fifth and final
 columns contain reference measurements. The 25th column contains no data;
 this channel on the multiplexer was broken. The remaining columns (six
 through twenty-eight, skipping twenty-five) contain data from Rock1,
 Plate2, Plate3, Rock4, Plate7, Plate6, Rock5, Rock8, Plate9, Plate10,
 Plate11, Rock12, Plate13, Plate14, Plate15, Plate16, Plate17, Rock18,
 Rock19, Plate21, Rock22 and Plate23. Note that -6999 indicates
 NaN. Raw_bio_data.csv contains the counts of sessile
 and mobile organisms on plate and bedrock samples determined in August and
 December of 2013 and March and June of 2014. Rows correspond to species
 surveyed. Columns indicate the month and location of the sample. For
 example, "AugP2" indicates the organism counts from August 2013
 on Plate 2. "Aug2.1", "Aug2.2" and "Aug2.3"
 indicate the organism counts from August 2013 on the first, second and
 third randomly-selected, 10x10 cm plots of bedrock adjacent to Plate 2,
 respectively. These counts were averaged, and represent the biological
 data corresponding to the Rock1 temperature data.