Data from: Conspecific mortality and resource availability drive a trait-mediated cascade by modifying sea urchin grazing behavior
Data files
Sep 10, 2026 version files 282.45 KB
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README.md
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Urchin_Behavior_Grazing_Data_for_open_access.xlsx
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Abstract
Behavioral observation data of purple sea urchin position within subtidal cages in response to predation risk cues and food availability. Experiments were conducted in the field in Pacific Grove, California, USA. This includes data from several experiments testing sea urchin behavioral response to 1) a predator cue (banded rock crab) and a damaged conspecific cue (crushed urchin), 2) a test of the duration of urchin response to a single damaged conspecific cue (crushing) event, 3) drift kelp addition and a damaged conspecific cue (crushed urchin), 4) summary of categories from other experiments to compare the effect of lab feeding on urchin response to crushing. Most experiments lasted 48 hours and contained 4 observations each day. Twenty experimental cages were used and each contained 20 urchins. Counts of urchins in each habitat category for each cage at each timepoint are recorded in the data, along with summary categories of types of urchin positions (e.g., exposed kelp grazing urchins).
https://doi.org/10.5061/dryad.f1vhhmh3g
Data from experiments described in: https://doi.org/10.1007/s00442-026-05949-8
Journal name: Oecologia
Authors: Casey J. Sheridan and Zachary H. Randell
File: Urchin_Behavior_Grazing_Data_for_open_access.xlsx
This file provides data on sea urchin behavior in the form of counts of the number of urchins in different locations within a cage (e.g. side, corner, edge, stone tops) from a series of several subtidal experiments described in the corresponding manuscript. Also included are the number of surfaces the urchin touching when appropriate, and whether the urchin was interacting with live kelp (denoted by K) or drift kelp (denoted by D).
Columns to the far right give sums of urchins in categories (from multiple location columns) such as exposed stone top grazing urchins and urchins seeking refuge (see methods and supplemental for more details on categories) that were used in the analysis.
Sheets: Each sheet corresponds to a separate experiment
Sheet: CrabxCrush: manipulation of predator cue (banded rock crab) and conspecific mortality cue (crushing), unfed urchins, 2 trials
Sheet: Crush_Response_Duration: single trial testing the duration of sea urchin behavioral response to a single crushing event
Sheet: DriftxCrush: manipulation of drift kelp (detached kelp blades) and conspecific mortality cue (crushing), fed urchins, 2 trials
Sheet: Lab feeding x Crush: comparison of summary categories from CrabxCrush and DriftxCrush. Uses +/-Crush and -Crab from CrabxCrush and +/-Crush and -Drift from DriftxCrush to compare the effect of feeding on crushing response.
Overview of columns found on each sheet: Most columns are shared between sheets (metadata and urchin behavior categories). Some sheets have columns added or removed based on the details of the experiment.
CrabxCrush: has an additional column for averaged sampling interval and a column for crab position
Crush_Response_Duration: contains a subset of the CrabxCrush columns, no columns associated with crabs
DriftxCrush: contains an additional column of each possible behavioral category with a “D” (e.g., Surface Bottom D) to denote urchins in that position associated with Drift kelp. Also has more additional columns for stone edge. Column headings specify “Live” kelp to differentiate from “Drift” kelp. Contains additional summary of urchin location columns expressed as proportions.
Lab feeding x Crush: Contains summary columns taken from CrabxCrush and DriftXCrush for cages that match the appropriate treatment levels (no +predator cages and no +drift cages).
Variables
Metadata
- Experiment: the overall experimental manipulation
- Cage #
- Observer: diver who recorded the data
- Date
- Trial: trial number of that particular experiment
- Sampling sequence: which round of observations the sampling was
- Time: (start or range, 24hr): the time the sampling sequence began (single time) or the range over which the sampling sequence was conducted (start and end time)
- Sampling Interval: time elapsed since the begin of the experiment (e.g., first crushing)
- Averaged Sampling Interval: averaged sampling interval across the two trials for that particular sampling sequence
- Treatment: the particular treatment level for that cage, a combination of crushing (+/-) and either predator (+/-) or drift (+/-) depending on the experiment
- Crush: with or without the treatment consisting of adding 2 crushed urchins daily
- Predator: with or without the treatment consisting of adding a banded red rock crab
- Drift: with or without the treatment consisting of adding detached drift kelp
Urchin Behavioral Observations (counts of urchins in each location)
- Surface categories indicate an urchin is touching one surface on the bottom, side or top of the cage.
- K denotes an urchin in contact with live kelp. C denotes an urchin is on the set of paving stones with the crushed urchin packet. E denotes an urchin is on the edge of the paving stone.
- Surface Bottom
- Surface Bottom K
- Surface Side
- Surface Side K
- Surface Top
- Surface Top K
Corner categories indicate an urchin touching two surfaces in the one of the four corners on the bottom or top of the cage.
- Corner Bottom
- Corner Bottom K
- Corner Top
- Corner Top K
Edge categories indicate an urchin touching two surfaces at the edge of the bottom, side or top of the cage.
- Edge Bottom
- Edge Bottom K
- Edge Side
- Edge Side K
- Edge Top
- Edge Top K
Stone top categories indicate an urchin exposed on top of one of the four paving stones.
- Stone Top
- Stone Top K
- Suspended Kelp
- Stone Top C
- Stone Top CK
- Stone Top E
- Stone Top EC
- Stone Top EK
- Stone Top ECK
Stone Plus and +Edge categories indicate an urchin touching two surfaces or concealed in the area between the four paving stones. The parenthetical (1 side) indicates the urchin is only touching one surface and thus would not be categorized as “refuge-seeking”.
- Stone Plus
- Stone Plus K
- Stone +Edge
- Stone +Edge K
- Stone +Edge (1 side)
- Stone +Edge (1 side) K
- Stone +Edge (1 side) C
- Stone +Edge (1 side) CK
Sums of urchin counts in particular categories
- Total Urchins Observed
- Total Exposed Urchins: total number of urchins touching one surface
- Exposed Stone Top Urchins: total number of urchins touching one surface on the stone tops
- Exposed + Live Kelp Urchins: total number of urchins touching one surface and interacting with live kelp
- Refuge-seeking Urchins: total number of urchins touching two or more surfaces
- Stone Exposed Kelp Associated Urchins: total number of urchins touching one surface on the stone tops and interacting with live kelp
- Proportion Stone Top Exposed Kelp: proportion of exposed urchins interacting with kelp based on the total number of urchins in the cage
- New proportion exposed: proportion of exposed urchins based on the total number of urchins in the cage
- Proportion refuge seeking: proportion of urchins touching two surfaces based on the total number of urchins in the cage
- Crab Position: the location of the crab during sampling observations for cages with a treatment level that included a banded rock crab
- Proportion Drift Associated Urchins: proportion of urchins touching a piece of drift kelp (all urchins in a category with a D)
Observation data collected visually on SCUBA at four time periods each day. Counts of urchins were recorded in predefined categories.
For detail described of methods see: Sheridan, C.J., Randell, Z.H. Conspecific mortality and resource availability drive a trait-mediated cascade by modifying sea urchin grazing behavior. Oecologia 208, 114 (2026). https://doi.org/10.1007/s00442-026-05949-8