DOI: 10.5061/dryad.r2280gbkt
title: Data from: intertidal mussels as ecosystem engineers: maintenance of invertebrate assemblages amid intertidal stress gradients

description: In this study, we measured univariate and multivarite metrics of mobile
 invertebrate assemblages along the midlittoral vertical range of four
 replicate rocky shores, aiming a control habitat (barnacle cover) and a
 facilitated habitat (barnacle cover plus a secondary mussel cover). At any
 given shore height, differences between assemblages would indicate
 realized facilitation. Temperature and desiccation potential increase from
 the bottom to the top of this range, and increased facilitation higher on
 the shore would support the stress-gradient hypothesis. Along with
 invertebrate data, we provide key environmental data at study sites that
 could underlie any spatial structure on top of local vertical trends.
description: Environmental parameters at study sites were estimated following
 standard techniques in intertidal ecology (i.e. shore characteristics). A 
 compass was used to estimate shore orientation. A digital clinometer
 measured shore inclination. Measuring tapes, water hoses and rulers were
 used to measure shore inclination, shore height and mussel bed cross-shore
 size. A digital thermometers coupled to a pointed probe was used to
 measure interstitial temperature. In the lab, mobile
 invertebrates were sorted out from samples through washing and sieving and
 counted/identified under a dissecting microscope.
description: # Intertidal mussels as ecosystem engineers: maintenance of invertebrate
 assemblages amid intertidal stress gradients
 The file contains
 different folders describing sampling sites and containing data on
 environmental characteristics of sites, mussel beds, and invertebrate
 identifications and counts. ## Description of the data and file structure
 The five sheets of the file organize the data in the different aspects of
 the study. 1\) Metadata – informs the sampling period, site names and
 abbreviations, distance between sites (km) and coordinates in decimals.
 2\) Main – includes invertebrate counts and identifications for all
 samples. ‘Site’ stands for the sampled rocky shores (Guaecá, Feiticeira,
 Itassucê and São Pedro); ‘Date’ for the sampling date; ‘Treatment’ for
 sampled habitat [control vs facilitated (= bed)]; ‘Level’ for the height
 within the mussel-bed vertical range (low, mid and high); ‘Replicate’ for
 each replicate sample (n = 5) within all combinations of
 site*treatment*level. Invertebrates were identified in major taxonomic
 groups: scientific and common names are given in lines 1 and 2,
 respectively. 3\) Mussel length & width – provided the morphometric
 data needed for mussel identifications (n = 10 for all site*level
 combinations), which are based on the size-specific height/length (H/L)
 ratios given by Tanaka & Magalhães (1999). This reference is given in
 the main paper. All measurements are given in mm. 4\) Temperature –
 Replicate measurements of interstitial temperature (oC, n = 15) at the
 control (Control: C) and the facilitated habitat (Bed: B), for all
 combinations of shore*level. Average temperature (T average) is a
 surrogate of overall temperature.    5\) Orientation_Slope_Height –
 Environmental characteristics of sampled shorelines. ‘Orientation’ refers
 to where the rocky shore is facing (n = 5, North = 0 / 360o); ‘Slope’
 stands for shore inclination (in degrees, n = 30); ‘Height’ stands for
 shore height above water level (cm, n = 5) at the lower and upper limits
 of mussel beds (the subtraction of those limits gives their vertical
 span); ‘Height above chart datum’ (cm) corrects for differences between
 the water level at the sampled time and chart datum.