Table of Contents

• Dataset Description
  • Methods & Sampling
  • Data Processing Description
• Related Datasets
• Parameters
• Deployments
• Project Information
• Funding

This data set includes abundances of Strongylocentrotus purpuratus (purple sea urchin) and their burrows on transects along the California coast from 37.9 N to 39.3 N.

Access Restriction: Access to these data are restricted until publication of the associated manuscript, which is currently in review at PLOS ONE. [2015-02-05]

Related Datasets:
Henricia counts
Purple urchin density
Seastar and chiton counts - quadrats and swaths
CHIPS02 - seastar chiton urchin counts in quadrats

Subtidal transects for S. purpuratus

SCUBA diver surveys have been conducted, between July and October of each year since 2005, as part of regular monitoring efforts by California Department of Fish and Wildlife. Pairs of divers counted urchins in 30 x 2 m transects in rocky reef habitats in three approximate depth classes at each site (2–10 m, 10–15 m and 15–20 m). Transects were placed at pre-selected random GPS coordinates within each depth stratum, and new random coordinate locations were generated for each survey year. At each site, divers initiated 18 transects in the shallow depth stratum and 9 transects in each of the two deeper strata. Ocean conditions impacted the number of transects completed at each site in any given survey year.

BCO-DMO Processing Notes:

• added conventional header with dataset name, PI name, version date, reference information
• renamed parameters to BCO-DMO standard
• added longitude column

This project is a Collaborative Research project funded by an NSF RAPID grant.

Description from NSF award abstract:
The potentially important role that larval dispersal may play in determining gene flow, distributions, and population structure of marine invertebrates remains unclear despite many hundreds of descriptive comparisons of pelagic duration and population genetic structure. This lack of clarity suggests many factors may influence population genetic structure and their interactions may be complex. Difficulties studying these factors include (under normal circumstances) distinguishing local from exogenous recruitment and therefore the true distribution of dispersal distances. For example, experiments that normally could be undertaken to explore this issue are very small scale relative to the distances that many marine taxa may disperse.

In August 2011, a large-scale natural removal experiment was initiated along a 100 km stretch of the central California coast. The PIs propose to use this rare opportunity to clarify the effects of dispersal and species interactions on marine population genetic variation and community structure. They propose to study three species that suffered very high rates of mortality: an ecosystem engineer (Strongylocentrotus purpuratus, ~100% mortality), a keystone species (Pisaster ochraceus, ~10-70% mortality), and one of its competitors (Leptasterias sp., ~100% mortality). Their objectives during this first year following the natural large-scale die-off are to:

(1) quantify the abundance and distribution of the target species at sites across the impacted range and reference sites to the south and north,
(2) develop and use genetic markers to identify the sources and dispersal distances of new recruits of P. ochraceus, Leptasterias sp., and S. purpuratus that recolonize the impacted range, and
(3) describe changes in abundance of these three species and their prey and competitors at sites throughout the impacted range.