Table of Contents

• Coverage
• Dataset Description
  • Methods & Sampling
  • Data Processing Description
  • BCO-DMO Curation Notes
• Data Files
• Supplemental Files
• Related Publications
• Related Datasets
• Parameters
• Instruments
• Deployments
• Project Information
• Funding

Samples were collected on CCE-NSF process cruise (OCE-1637632, Project: California Current Ecosystem Long Term Ecological Research Site). 

Pyrosomes were collected for abundance and size-structure estimates using a double-oblique tow with a Bongo frame equipped with paired 202 μm nets, a temperature-depth logger, and a General Oceanics flow meter affixed to the Starboard net. Bongo tows were conducted twice daily for day and night sampling, at approximately 1000 h and 2200 h, following standard CalCOFI protocols (Bowlin et al. 2009). The average tow time (± SD) was 23 ± 3 min, the average depth of sampling was 206 ± 14 m, and the average volume filtered was 290 ± 28 m3. Upon retrieval, the cod-end contents of the starboard net were gently transferred to a bucket and anesthetized with carbonated water to prevent regurgitation of gut contents (Kleppel and Pieper 1984). All pyrosomes were removed from the tow and rinsed to remove any hitchhiking zooplankton. The pyrosomes were then imaged, counted, and split into the respective subsamples. Depending on which pyrosomes were measured, the split factor accounts for the fraction or the whole percentage that the counts, and thus the lengths, represent of the tow. 

Pyrosomes were carefully removed and rinsed with filtered seawater to remove any attached zooplankton, placed in a black bin equipped with a ruler, and imaged from above with an iPhone, ensuring a ruler was included in the image (n=1384 to the nearest mm). Images were reported in cm, but our resolution allowed the measurement to the nearest mm, using the ruler in the image.   Images were used to quantify population size-structure using ImageJ.

* Imported the file and treated blank cells and “nd” as missing values.
* Converted the Date column from M/D/YY format to the standard ISO date format YYYY-MM-DD.
* Unpivoted the "Total Pyrosome Lengths" column and all numbered columns matching pattern "(N)" into a single "pyrosome_length" value column, creating a new "pyrosome_index" key column indicating which original column each value came from (0 for "Total Pyrosome Lengths", otherwise the number in parentheses) into long format & filtered out rows where pyrosome_length was null (unnecessary rows after unpivot, original data didn't always have the same amount of measurements.)
* Exported the cleaned and standardized tables as CSV files.

NSF Award Abstract:
A key component of the ocean food web is comprised of floating animals, or zooplankton, that transfer energy from phytoplankton to fish, whales, and birds. Zooplankton include many different types of organisms that can be broadly categorized as crustacean or gelatinous, with most fish and whales preferring crustaceans as a fat-rich food source over gelatinous animals, which are higher in water content. Historically, the California Current ecosystem off the U.S. West Coast has been dominated by crustacean zooplankton, such as krill and copepods, but in 2014 there were huge abundances of a type of colonial, gelatinous zooplankton known as pyrosomes, which caused widespread damage to fisheries by fouling fishing gear and dominating catch. Although the arrival of pyrosomes coincided with an extensive marine heatwave, lower abundances have since persisted despite a return to cooler ocean temperatures. Analysis of time series data from the California Cooperative Oceanic Fisheries Investigations (CalCOFI) indicate that pyrosomes were also observed in the California Current many decades ago when the ocean was not particularly warm. This study combines analysis of past samples from CalCOFI, ocean circulation models, and biological models to understand the causes of these quickly growing pyrosome populations in the California Current. It supports training for undergraduate and graduate students. In addition, the project is reaching K-12 students through a unique partnership with the San Diego County Office of Education that is developing Next Generation Science Standards (NGSS)-aligned resources for middle and high school science teachers in California. The educational resources are being disseminated through the California Science Project and California Environmental Literacy Initiative. Public outreach in San Diego (CA) is through the Enhancing Your Horizons San Diego conference and the San Diego Regional Competition of the National Ocean Sciences Bowl, and in Santa Cruz (CA) through the Seymour Marine Discovery Center.

Predicting how ecosystems respond to accelerating climate change is a major challenge. The recent appearance of the pyrosome Pyrosoma atlanticum in the California Current is a major perturbation to the ecosystem, and the cause remains unknown. Both ocean physics and plankton food-web dynamics are key determinants of variability in pelagic community composition in this ecosystem, yet unraveling the degree to which variability in physics (through warming and advection) combines with shifting biological interactions (through nutrient cycling and altered food-web dynamics) to determine composition and function is complicated. This project combines the analysis of past historical samples from seven decades of the CalCOFI time series, data-assimilative and non-data assimilative ocean circulation models, and biological population models to determine the role ocean physics and biological interactions have played in shaping pyrosome abundance, trophic dynamics, and population growth and mortality in the California Current. This novel framework is providing mechanistic understanding that is required to predict how plankton communities respond to climate change.

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.