The Cupid Cohort Turns One
It was a coincidence that the first successful sunflower star spawning event in California happened on February 14th, 2024, or Valentines day. Pycnopodia helianthoides, or sunflower sea stars, are broadcast spawners. This means they release their eggs and sperm directly into the water column, and hope to find their counterpart nearby in order to accomplish fertilization. To achieve this under human care, 1 male and 1 female star were induced with, 1-Methyladenine, a naturally occurring hormone in sunflower stars that biologically cued their bodies to release their respective gametes. After 6 hours, some Marvin Gaye songs blasted in the room, and a lot of anxious waiting, the stars began to release their gametes. “The squeals” says Ashley Kidd, the Conservation Aquaculture Project Manager of the Sunflower Star Laboratory (SSL).
Birch Aquarium’s sunflower star spawning system, decorated for a Valentine’s Day spawning
Sunflower sea stars were never a commercially or recreationally collected species, and there has never been a human need to cultivate them. Historically, they are not used as food, or any other cultural purpose. They grow quickly, and live a long time. There is currently no mechanism for aging the stars. This makes it difficult to research, track in aquariums, or in the wild.
When Pycnopodia started experiencing Sea Star Wasting Syndrome (SSWS) in 2013, no one knew why or how to help. Wasting has been observed among sea stars around the world for centuries, however; the stars on the west coast in 2013 began experiencing something different, which was that multiple species were affected over thousands of miles, with Pycnopodia being the most acutely affected. Since then, their population on the West Coast has decreased drastically, becoming functionally extinct on the California coast. By 2018, 5% of the population remains, with recovery lagging behind other sea star species, while SSWS remains an active threat.
Sunflower stars are one of the main predators of purple urchins, and with the stars gone, these urchins are over-consuming the kelp forests. Pairing this with the loss of kelp cover in Central and Northern California due to environmental factors, like the loss of sea otters, another keystone species, Purple urchin populations have endured a behavioral shift, where the lack of food and predators makes them graze more actively. Once exhausted, they lie dormant where the kelp previously was, subsisting off biofilms and preventing new kelp from establishing.
A female Pycnopodia begins to release her eggs, as a scientist is at the ready to collect. Photo credit Ashley Kidd.
The 2024 spawning event did not come together overnight. In February 2024, “all the stars aligned”, says Kidd. The collaborators involved are really what made the party happen. Birch aquarium had the sea stars, Cal Academy brought their inducing protocols, the San Diego Zoo Wildlife Alliance brought cryopreserved sperm, Sunflower Star Laboratory and Aquarium of the Pacific provided collective experience in spawning and fertilizing eggs. After the eggs and sperm were released, they were collected, and brought together to complete fertilization.
With rough calculations, the groups estimated they had created around 10 million embryos. “Getting both male and female [to spawn] was the first win, and the second win was actually being able to see that through our sperm dilutions and the fertilization, we actually had 100% fertilization for all of them…it was a wonderful feeling” said Kidd. The embryos were later distributed to 5 different establishments, the Cal Academy of Science in San Francisco, Moss Landing Marine Labs (MLML), Cal State Long Beach, Aquarium of the Pacific in Long Beach, and Birch Aquarium in San Diego. The Sunflower Star Laboratory was building a new laboratory location through all this, but still played an integral role in the larval rearing with Moss Landing Marine Labs (MLML). Weekly samples of larvae were photographed and measured by SSL’s lab team and some of the larvae soon began to “settle,” meaning they left their planktonic phase and began life as juvenile bottom-dwelling stars. By May, SSL had its first sea table system built and cycled, and 400 juveniles arrived from MLML. They lived in a community tank, and by June, there were just under 40. You can read more about their adventures in the voracious recently-settled phase in A Cannibal’s Tale. Sunflower Star Laboratory now has 61 one-year-old individuals, with the Cupid Cohort having 247 in total across 8 institutions, at the end of 2024.
Early settled sunflower stars. First picture showing full grown purple urchin spines and tube feet, larger than the stars at the time.
Ashley Kidd's role in this event was crucial. She obtained her MS in Fisheries and Aquatic Sciences from the University of Florida, and worked for 12 years as a public aquarium professional. From participating in other successful collaborative conservation efforts, such as the White Abalone Recovery Program and SECORE coral conservation, Ashley intentionally pursued partnerships from her academic and aquarium contacts. These establishments had the required culture skills and knowledge to advance the action items involving culture work and ex situ population management set forth by the Roadmap to Recovery.
One important concept that Ashley helped put together with the help of San Diego Zoo and Wildlife Alliance was the implementation of Cryopreservation. Cryopreservation is the process of preserving tissue, cells, and other biological materials at extremely low temperatures for future use. This is important for keeping Pycnopodia genetic diversity within an ex situ sea star population for future and sustained conservation efforts.
The future's looking bright at the Sunflower Star Laboratory. With 61 growing individuals, the staff and interns are working on daily care and monitoring. Since there is still so much unknown regarding the Pycnopodia growth process, a huge job that the staff possesses is gathering as much data as they can. With feeding trials, behavior tracking, and regular measurements to track growth rate, SSL is chipping away at some of the basic answers for scaling up the culture of these stars and advancing the mission of building resilient kelp forests. “SSL is dedicated to doing just that” states Kidd, because as a collective, “we are actually hitting the milestones we set out to hit,” hoping to keep this momentum going to accelerate recovery research planning in the state, to integrate into the already established kelp ecosystem recovery programs.
One of the Cupid Cohort, almost a year after the spawning.
The Cupid Cohort has contributed beyond Sunflower Star Laboratory’s larger kelp conservation and restoration initiatives. The collective efforts of everyone involved is what made that happen. Kidd states that there was “very little arm-twisting” when it came to organizing with the collaborators. Kidd attributes much of this success to how willing and excited everyone has been, and that partners are embracing the skill sets they have honed on other species to make a successful first attempt based on the guidance and support from the Pycnopodia Recovery Working Group (PRWG), as well as Jason Hodin’s team at Friday Harbor Labs. There is lots of hope in the natural human desire to help this species restore, as well as West Coast kelp forests as a whole.
One Year Later
After a full year of growth, these stars have already accomplished a lot. The group being taken care of by the Sunflower Star Laboratory is the largest grouping from the cohort. They all have their individual quirks and differences, varying from sizing, colors, and arm count. The group is providing a space for young budding research, which has been previously gone undetected. The largest of the stars in SSL’s group is Olive. Her and her Star siblings have been feeding on mussels, brine shrimp, and Mysid shrimp.
