Flexible resource investment is a risk-sensitive reproductive strategy where individuals trade resources spent on reproduction for basic metabolic maintenance and survival. This study examined morphological variation in herbivorous sea urchin grazers across a mosaic landscape of macroalgae-dominated habitats interspersed with patches of sea urchin barrens to determine whether sea urchins shift energy allocation in response to food limitation. Extensive underwater surveys of habitat attributes (e.g., sea urchin density, algae cover) were paired with detailed laboratory assays (e.g., sea urchin dissections) to determine how resource abundance affects energy allocation between reproductive capacity and body structure in the purple sea urchin, Strongylocentrotus purpuratus. We found that: (1) sea urchins had a more elongate jaw structure relative to body size in habitats void of macroalgae (i.e., barrens), (2) sea urchin reproductive capacity (i.e., gonad index) was lower in barrens and the barrens habitat was primarily comprised of encrusting algae, and (3) sea urchin jaw morphology (i.e., lantern index) and reproductive capacity (i.e., gonad index) were inversely related. These results suggest that sea urchins respond to macroalgae limited environments by shifting energy allocation between reproductive capacity and modifications of the foraging apparatus, which may explain the ability of sea urchins to persist in low resource environments.  

READ_ME
This file explains all of the variables in each of the datasets required to conduct the analyses used in the manuscript, “Variation in purple sea urchin (Strongylocentrotus purpuratus) morphological traits in relation to resource availability.” These data were generated from benthic subtidal surveys led by Joshua G. Smith.

Urchin_data.csv
This data file contains information on habitat attributes and sea urchin morphometrics collected from benthic surveys along the Monterey Peninsula, CA, USA in the year 2017. All data reported are summarized at the size level, reported as mean values recorded from 1x1m quadrats.

zone_data.csv
This data file contains data summarized by test Log_TD for plotting the relationship between lantern length and gonad weight.

Smith_raw_data_file.csv
This data file contains unsummarized, raw sea urchin dissection data.

Smith & Garcia.Rmd
This file contains the code used to analyze the data in, “Variation in purple sea urchin (Strongylocentrotus purpuratus) morphological traits in relation to resource availability.”