Nav: Home

New SDSU study examines role of sea urchins on California kelp

March 14, 2019

SAN DIEGO, Calif. (March 14, 2019) - California sheephead and spiny lobsters may be helping control sea urchin populations in Southern California kelp forests, where sea otters -- a top urchin predator -- have long been missing, according to a new San Diego State University (SDSU) study published in the journal Ecology. The research provides new insight into the complex predator-prey relationships in kelp forests that can be seen in the absence of sea otters.

The study is also the first to experimentally test the relative impact, or rate of feeding, of the California sheephead and spiny lobsters in comparison to sea otters, whose historical range spanned from British Columbia, Canada to Baja California, Mexico.

"Healthy kelp forests are important both economically and ecologically along our coast. They act as nurseries and vital habitat for valuable fishery species, recreation sites for kayakers, free divers, and scuba divers, and serve as the base of rocky reef food webs," says Robert Dunn, who led the study as a Ph.D. candidate at SDSU and University of California, Davis, funded by a NMFS-California Sea Grant Fellowship.

Kelp forests rely on the proper balance of herbivory and predation. Sea urchins dwell on the seafloor where they forage on macroalgae, including giant kelp. If their populations are left unchecked by predation, they can decimate kelp forests and prevent kelp from growing. That can transform a thriving community of kelp into an oceanic desert, known as an urchin barren.

The relationships between predators and prey vary among communities. Sea urchins have recently decimated kelp forests in Northern California, leaving researchers to wonder why Southern California kelp forests have remained relatively intact without sea otters to control the urchin populations.

Past research has indicated that Marine Protected Areas in Southern California house a diversity of predators -- warranting fewer urchins and abundant kelp. Dunn and his SDSU graduate advisor, Kevin Hovel, set out to better understand the potential for top-down control by these two distinct predators: the California sheephead and spiny lobsters.

"One of the main things to note about Robert's research is that he was able to experimentally control, for one of the first times, many factors that allow us to test whether or not these predators have the right amount of influence, whether they can eat fast enough, and if there are enough of these predators within the ecosystem to exert strong influences on sea urchins," says Hovel, a professor of biology at the Coastal and Marine Institute at SDSU.

The new findings are in line with concurrent international research. Dunn said another recent study in southern Australia "found comparable results that predators and disease seem to be able to control urchins up to a certain density, similar to the number we found, but once urchins get to really high densities, those two factors no longer regulate urchin populations. Since our results are in line with findings on other rocky reefs, we believe this to be solid evidence indicating our results are robust."

The new research provides valuable information to understand and protect California's quintessential kelp forests. The researchers note, however, that further research is needed to tease out the complex relationships between sea urchins and their predators.

"These results shed light on a very nuanced relationship, that requires further research on rocky reefs around the globe," says Dunn. "At the same time, we are already experiencing effects from global climate change, which will have additional consequences for these important ecosystems."

Throughout his fellowship experience, Dunn has connected with National Marine Fisheries Service (NMFS) researchers and collaborators at UC Davis to follow up on this work utilizing a modeling approach to assess what happens in the absence of fishing for lobsters and urchins in kelp forests. Dunn recently started a postdoctoral position with Hovel at SDSU to build on the reported research, assessing spiny lobster demographic rates, food web positions, and genetic population structure, also with California Sea Grant funded support.
-end-
About California Sea Grant

NOAA's California Sea Grant College Program funds marine research, education and outreach throughout California. Our headquarters is at Scripps Institution of Oceanography, University of California, San Diego; we are one of 33 Sea Grant programs in the National Oceanic and Atmospheric Administration (NOAA), U.S. Department of Commerce.

About San Diego State University

San Diego State University is a major public research institution that provides transformative experiences, both inside and outside of the classroom, for its more than 36,000 students. The university offers bachelor's degrees in 95 areas, master's degrees in 78 areas and doctorates in 22 areas. Students participate in research, international experiences, sustainability and entrepreneurship initiatives, internships and mentoring, and a broad range of student life and leadership opportunities. The university's rich campus life features opportunities for students to participate in, and engage with, the creative and performing arts, a Division I athletics program and the vibrant cultural life of the San Diego region. For more information, visit http://www.sdsu.edu.

San Diego State University

Related Relationships Articles:

Better quality relationships associated with reduced dementia risk
Positive social support from adult children is associated with reduced risk of developing dementia, according to a new research published today.
Contraception influences sexual desire in committed relationships
How often women in heterosexual couples desire sex depends on how committed the relationship is and what type of birth control the woman uses.
Health determined by social relationships at work
Recent research shows higher social identification with one's team or organization is associated with better health and lower stress.
Financial relationships between biomedical companies and organizations
Sixty-three percent of organizations that published clinical practice guidelines on the National Guideline Clearinghouse website in 2012 reported receiving funds from biomedical companies, but these relationships were seldom disclosed in the guidelines, according to a new study published by Henry Stelfox and colleagues from the University of Calgary, Calgary, Canada, in PLOS Medicine.
Money really does matter in relationships
Our romantic choices are not just based on feelings and emotions, but how rich we feel compared to others, a new study published in Frontiers in Psychology has found.
Does frequent sex lead to better relationships? Depends on how you ask
Newlywed couples who have a lot of sex don't report being any more satisfied with their relationships than those who have sex less often, but their automatic behavioral responses tell a different story, according to new research published in Psychological Science, a journal of the Association for Psychological Science.
Concussion can alter parent-child relationships
A study published in the Journal of Neuropsychology, reveals the adverse effects of mild traumatic brain injury on the quality parent-child relationships.
Emotionally supportive relationships linked to lower testosterone
Science and folklore alike have long suggested that high levels of testosterone can facilitate the sorts of attitudes and behavior that make for, well, a less than ideal male parent.
Memory is greater threat to romantic relationships than Facebook
A new study was designed to test whether contacts in a person's Facebook friends list who are romantically desirable are more or less of a threat to an existing relationship than are potential partners a person can recall from memory. threatened current committed relationships, as reported in an article published in Cyberpsychology, Behavior, and Social Networking.
How does prison time affect relationships?
A new study highlights the complicated spillover effects of incarceration on the quality of relationships.

Related Relationships Reading:

Best Science Podcasts 2019

We have hand picked the best science podcasts for 2019. Sit back and enjoy new science podcasts updated daily from your favorite science news services and scientists.
Now Playing: TED Radio Hour

Don't Fear Math
Why do many of us hate, even fear math? Why are we convinced we're bad at it? This hour, TED speakers explore the myths we tell ourselves and how changing our approach can unlock the beauty of math. Guests include budgeting specialist Phylecia Jones, mathematician and educator Dan Finkel, math teacher Eddie Woo, educator Masha Gershman, and radio personality and eternal math nerd Adam Spencer.
Now Playing: Science for the People

#517 Life in Plastic, Not Fantastic
Our modern lives run on plastic. It's in the computers and phones we use. It's in our clothing, it wraps our food. It surrounds us every day, and when we throw it out, it's devastating for the environment. This week we air a live show we recorded at the 2019 Advancement of Science meeting in Washington, D.C., where Bethany Brookshire sat down with three plastics researchers - Christina Simkanin, Chelsea Rochman, and Jennifer Provencher - and a live audience to discuss plastics in our oceans. Where they are, where they are going, and what they carry with them. Related links:...