Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Processing Description
  • Problem Description
• Related Publications
• Parameters
• Instruments
• Project Information
• Funding

Data were collected during day-trips aboard California Department of Fish and Wildlife or NOAA patrol boats, generally 2-5 days at select survey locations in 1999, 2000, 2001, 2003-2019, 2022, and 2023.

All surveys were done using SCUBA along 30x2 meter (m) transects (60 square meters total area) randomly placed in the subtidal zone in rocky habitats dominated by bull kelp (Nereocystis luetkeana) forests. These randomly placed band transect surveys were stratified by depth (A=0-15, B=16-30, C=31-45, D=46-60 ft) as we know sea urchin and abalone populations differ by depth. Two divers (a dive team) work together to count and measure organisms.

Divers were deployed as teams to randomly-selected GPS waypoints within designated depth strata (A, B, C, D). Divers typically complete multiple transects within each of the four depth strata ranging from 0 to 60 feet at each site. Divers swim along transect tapes measuring 30 x 2m in area across the rocky reef. All transect surveys were in habitat dominated (>70% rock) by rocky reef.

Emergent Surveys:
Emergent sampling focused on emergent, exposed, or cryptic animals in rock crevices or under rock ledges but visible without turning rocks or the use of a flashlight. Data collected on the transects include depth of transect, dive number, the number of each species of abalone and sizes of Haliotis rufescens, pinto abalone (H. kamtschatkana), flat abalone (H. walallensis), number of sea urchins (red, Mesocentrotus franciscanus, or purple, Strongylocentrotus purpuratus) and size as time allowed, number of associated species and predators, substrate, algal type percent cover. Where needed divers mark abalone shells with yellow forestry crayons to avoid duplicate counts and measures. Data from each dive were recorded on waterproof datasheets which the divers fill out along the transect. Upon return to the boat, data sheets were checked by the lead diver to ensure accuracy and readability for the first field site quality control check.

Rapid Emergent Surveys:
In response to the extreme purple sea urchin population increase and abalone mortality event in 2016-18, survey methodology changed somewhat with fewer transects per site (approx. 12 per site). Divers conducted a rapid assessment sampling technique: Rapid Emergent Abalone Surveys were similar to standard emergent surveys (see above) but focused on purple sea urchin and red abalone counts of live and dead abalone and sea stars. Divers conduct two to four rapid emergent transects per dive.

Primary data collected on each rapid transect are number of live, dying, and dead red sea urchins, purple sea urchins, red abalone, pinto abalone, and flat abalone, as well as empty abalone shells. Additional data collected (if bottom time and/or air allowed): red abalone size, number of associated species and predators, algal habitat coverage, substrate type, and presence of bull kelp. Abalone that were measured were marked with yellow forestry crayons to avoid duplicate counts and measures. As with the emergent surveys, the divers fill out data on waterproof datasheets along the transect. Upon return to the boat data sheets are checked by the lead diver to ensure accuracy and readability for the first field site quality control check.

The data specific to this dataset are the numbers of purple sea urchins, red sea urchins, red abalone, flat abalone, and pinto abalone, as well as associated species along each transect.

Data were entered from the field data sheets into a Microsoft Access database, where they were sorted and exported to Excel files. Once data were proofed, they were saved in a text file as comma-separated values (CSV).

- Imported original files "NSF_OCE_2023664_KelpForestSurveys_Species_CODES_v2_20240119.csv" (species code list) and "NSF_OCE_2023664_KelpForestSurveys_LOCATIONS_v4_20240105.csv" (site code list) into the BCO-DMO system.
- Imported original file "NSF_OCE_2023664_KelpForestSurveys_Species_COUNTS_v7_20240725.csv" (species counts) into the BCO-DMO system.
- Added the following columns from the site code list to the species count data: SiteName.
- Added the following columns from the species code list to the species count data: CommonName, ScientificName.
- Removed the non-standard character in Comments column in rows 2117 to 2130.
- Converted the SurveyDate column to YYYY-MM-DD format.
- On rows 22771 and 22772 of the original Excel file, the SurveyDate column has years of 2024 and 2025. Changed these to 2023 to match the Year column.
- Saved the final file as "927682_v1_kelp_forest_surveys_invert_species_counts.csv".

NSF Award Abstract:
Rapid and extreme warming events such as El Niño and marine heatwaves have had ecological and economic impacts on nearshore marine ecosystems. These impacts include reductions in biomass and collapses in commercial fisheries. For many species, population booms and busts are controlled by shifts in reproduction and juvenile dispersal related to warmer temperatures and ocean circulation. However, how population fluctuations are shaped by interacting processes that control adult reproduction and larval survival remains unclear. Marine heatwaves often accompany major disruptions in ocean circulation, which can affect survival and the distribution of species that produce free-floating, planktonic larvae. As a result, species can be impacted directly by temperature effects on organismal reproduction and survival, and indirectly by shifts in ocean circulation that affect larval success. This project is examining how the joint effects of temperature and ocean circulation are controlling populations of purple sea urchins (Strongylocentrotus purpuratus). To address project objectives, the team is developing oceanographic models to predict dispersal of planktonic larvae in combination with controlled experiments on adult reproductive success. This project is advancing the understanding of how ecologically important species respond to ocean temperature and circulation, which are forecast to shift under future climate change scenarios. Broader impacts of the project include training of students and post-docs in STEM and educational outreach. Curriculum development and implementation is occurring in collaboration with existing K-12 outreach programs that focus on underserved communities and under-represented groups. The goal is to empower the next generation of scientists to use integrative approaches to predict ecological consequences of climate change.

Purple sea urchins are an ideal species for studying the coupled impacts of warming and ocean circulation on recruitment and survival given a wealth of ecological and organismal data. The species has a mapped genome, can be transported large distances as larvae by ocean currents, and larval abundances in California exhibit orders of magnitude variation with heatwaves and El Niño fluctuations. To quantify the processes that shape spatial and temporal variability in larval supply, researchers are applying a novel combination of biophysical modeling, experiments and statistical modeling of long-term, high-resolution data on larval settlement across the Southern California Bight (SCB). Research module 1 is quantifying spatial and temporal patterns of larval transport using a 3D-biophysical model of the SCB. The model is testing how interactions among historical changes in ocean circulation and temperature, larval life history, and larval behavioral traits affect variation in larval supply in space and time. Research module 2 is focused on how temperature could affect spatial and temporal variation in egg production. Experiments are characterizing reproductive thermal performance curves and quantifying how these vary among populations and organismal history. A novel assay is assessing epigenetic regulation of gene expression associated with performance curves. Finally, Module 3 will integrate mechanistic models from Modules 1 and 2 to statistically assess their ability to explain spatial and temporal trends in a nearly three-decade dataset of larval settlement from six sites in the SCB. This is one of the first studies that integrates models of larval transport, reproductive performance and settlement data to empirically test how physical and biological processes affect local recruitment patterns in complex marine meta-populations.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.