Nav: Home

Tropical sea urchins caught between a rock and a hot place

August 12, 2016

The balmy waters of the Caribbean could turn into a deadly heat trap for countless tiny creatures. Authors of a new study conducted at the Smithsonian Tropical Research Institute (STRI) in Panama discovered that microscopic sea urchin eggs and larvae may suffer stunting or death when the water temperature spikes just a couple of degrees above normal, adding to the impact of climate change in already warm tropical oceans.

Sea urchins, pincushion-shaped relatives of the starfish, graze the sea floor from shallow coastal areas to deep ocean vents from pole to pole. Their young look nothing like them. Adults release millions of eggs and sperm into the water, which develop into pinprick-sized free-swimming larvae. Only a minute fraction will survive and metamorphose into adults. Scientists think the developmental stages from egg to larvae are extra sensitive to temperature changes, but very few studies compare the vulnerability of the offspring to that of the adults.

"That's because they're tiny and generally inaccessible," said Rachel Collin, STRI staff scientist and lead author of the new study, published in Ecology and Evolution in July. She and coauthor Kit Yu Karen Chan, now at the Hong Kong University of Science and Technology, collected and studied sea urchins from the lagoons around Bocas del Toro, Panama, which normally experience temperatures around 27 to 29 degrees Celsius (C). They exposed adults and offspring in various developmental stages to two hours of acute heat stress by placing them in water baths with temperatures ranging from 28 to 36 degrees C.

Early stage larvae of one common species, the green sea urchin, Lytechinus variegatus, died at temperatures above 32 degrees C, while eggs and late stage larvae died closer to 34 degrees C. Adults survived up to almost 35 degrees C. Long-term exposure to temperatures above 30 degrees C reduced larval survival and growth, with all larvae dying when temperatures reached 32 degrees C.

"We were surprised at how close these experimental temperatures were to what they already experience in the Caribbean," Collin said.

Field-station recordings show that near one of the collection sites in Bocas del Toro, water temperatures exceeded 30 degrees C during the two warmest months of the year. Larvae may be less tolerant of such conditions than adults.

Temperatures in the tropics continue to rise as a consequence of climate change, giving shallow-water sea urchins few survival options: acclimate to their new normal or shift to cooler, deeper waters or higher latitudes. The microscopic larvae develop during a critically short period of days to weeks and drift according to the currents.

Collin and Chan are gathering data for eight other species of sea urchins, including two species of sand dollar. They hope to compare differences in temperature tolerance in adults and offspring across species, which may help them identify which ones are the most sensitive to heat stress. Collin pointed out that while their experiments give them an upper limit for acute stress--such as midday with the sun directly overhead--long-term, chronic stress due to gradually warming waters may be just as detrimental but harder to measure.

"We can document the tolerance limits of these animals in the lab," Collin said. "But we still don't understand the impact of warming on sea urchin populations in the wild. No one really knows where the currents might sweep the tiny larvae and what temperatures they are exposed to once they leave the reef."
-end-
The Smithsonian Tropical Research Institute, headquartered in Panama City, Panama, is a part of the Smithsonian Institution. The Institute furthers the understanding of tropical nature and its importance to human welfare, trains students to conduct research in the tropics and promotes conservation by increasing public awareness of the beauty and importance of tropical ecosystems. STRI website.

Smithsonian Tropical Research Institute

Related Climate Change Articles:

Mysterious climate change
New research findings underline the crucial role that sea ice throughout the Southern Ocean played for atmospheric CO2 in times of rapid climate change in the past.
Mapping the path of climate change
Predicting a major transition, such as climate change, is extremely difficult, but the probabilistic framework developed by the authors is the first step in identifying the path between a shift in two environmental states.
Small change for climate change: Time to increase research funding to save the world
A new study shows that there is a huge disproportion in the level of funding for social science research into the greatest challenge in combating global warming -- how to get individuals and societies to overcome ingrained human habits to make the changes necessary to mitigate climate change.
Sub-national 'climate clubs' could offer key to combating climate change
'Climate clubs' offering membership for sub-national states, in addition to just countries, could speed up progress towards a globally harmonized climate change policy, which in turn offers a way to achieve stronger climate policies in all countries.
Review of Chinese atmospheric science research over the past 70 years: Climate and climate change
Over the past 70 years since the foundation of the People's Republic of China, Chinese scientists have made great contributions to various fields in the research of atmospheric sciences, which attracted worldwide attention.
A CERN for climate change
In a Perspective article appearing in this week's Proceedings of the National Academy of Sciences, Tim Palmer (Oxford University), and Bjorn Stevens (Max Planck Society), critically reflect on the present state of Earth system modelling.
Fairy-wrens change breeding habits to cope with climate change
Warmer temperatures linked to climate change are having a big impact on the breeding habits of one of Australia's most recognisable bird species, according to researchers at The Australian National University (ANU).
Believing in climate change doesn't mean you are preparing for climate change, study finds
Notre Dame researchers found that although coastal homeowners may perceive a worsening of climate change-related hazards, these attitudes are largely unrelated to a homeowner's expectations of actual home damage.
Older forests resist change -- climate change, that is
Older forests in eastern North America are less vulnerable to climate change than younger forests, particularly for carbon storage, timber production, and biodiversity, new research finds.
Could climate change cause infertility?
A number of plant and animal species could find it increasingly difficult to reproduce if climate change worsens and global temperatures become more extreme -- a stark warning highlighted by new scientific research.
More Climate Change News and Climate Change Current Events

Trending Science News

Current Coronavirus (COVID-19) News

Top Science Podcasts

We have hand picked the top science podcasts of 2020.
Now Playing: TED Radio Hour

Listen Again: The Power Of Spaces
How do spaces shape the human experience? In what ways do our rooms, homes, and buildings give us meaning and purpose? This hour, TED speakers explore the power of the spaces we make and inhabit. Guests include architect Michael Murphy, musician David Byrne, artist Es Devlin, and architect Siamak Hariri.
Now Playing: Science for the People

#576 Science Communication in Creative Places
When you think of science communication, you might think of TED talks or museum talks or video talks, or... people giving lectures. It's a lot of people talking. But there's more to sci comm than that. This week host Bethany Brookshire talks to three people who have looked at science communication in places you might not expect it. We'll speak with Mauna Dasari, a graduate student at Notre Dame, about making mammals into a March Madness match. We'll talk with Sarah Garner, director of the Pathologists Assistant Program at Tulane University School of Medicine, who takes pathology instruction out of...
Now Playing: Radiolab

What If?
There's plenty of speculation about what Donald Trump might do in the wake of the election. Would he dispute the results if he loses? Would he simply refuse to leave office, or even try to use the military to maintain control? Last summer, Rosa Brooks got together a team of experts and political operatives from both sides of the aisle to ask a slightly different question. Rather than arguing about whether he'd do those things, they dug into what exactly would happen if he did. Part war game part choose your own adventure, Rosa's Transition Integrity Project doesn't give us any predictions, and it isn't a referendum on Trump. Instead, it's a deeply illuminating stress test on our laws, our institutions, and on the commitment to democracy written into the constitution. This episode was reported by Bethel Habte, with help from Tracie Hunte, and produced by Bethel Habte. Jeremy Bloom provided original music. Support Radiolab by becoming a member today at Radiolab.org/donate.     You can read The Transition Integrity Project's report here.