Issue 77 - October 2021

Sex & The Symbiont: Can Algae Hookups Help Corals Survive?

Rice biologists’ discovery can be used to help climate-challenged reefs survive for now

A dinoflagellate tetrad cell that will soon split into four separate cells, captured by Rice University scientists through a confocal microscope. The cell’s four nuclei are depicted in red. Researchers at Rice and in Spain determined from experiments that these symbionts, taken from a coral colony in Mo’orea, French Polynesia, are able to reproduce both through mitosis and via sex. (Credit: Correa Lab/Rice University)

A little more sexy time for symbionts could help coral reefs survive the trials of climate change. And that, in turn, could help us all.

Researchers at Rice University and the Spanish Institute of Oceanography already knew the importance of algae known as dinoflagellates to the health of coral as the oceans warm, and have now confirmed the tiny creatures not only multiply by splitting in half but can also reproduce through sex.

That, according to Rice marine biologist Adrienne Correa and graduate student Lauren Howe-Kerr, opens a path toward breeding strains of dinoflagellate symbionts that better serve their coral partners.

Dinoflagellates not only contribute to the stunning color schemes of corals, but critically, they also help feed their hosts by converting sunlight into food.

“Most stony corals cannot survive without their symbionts,” Howe-Kerr said, “and these symbionts have the potential to help corals respond to climate change. These dinoflagellates have generation times of a couple months, while corals might only reproduce once a year.

“So if we can get the symbionts to adapt to new environmental conditions more quickly, they might be able to help the corals survive high temperatures as well, while we all tackle climate change.”

two scientist in a laboratory — Rice University’s Lauren Howe-Kerr, left, and Adrienne Correa discovered that symbiont algae found on corals in French Polynesia are able to reproduce via mitosis and sex. That could make it easier to develop algae that better protect coral reefs from the effects of climate change. Photo by Brandon Martin

In an open-access study in Nature’s Scientific Reports, they wrote the discovery “sets the stage for investigating environmental triggers” of symbiont sexuality “and can accelerate the assisted evolution of a key coral symbiont in order to combat reef degradation.”

To better understand the algae, the Rice researchers reached out to Rosa Figueroa, a researcher at the Spanish Institute of Oceanography who studies the life cycles of dinoflagellates and is lead author on the study.

“We taught her about the coral-algae system and she taught us about sex in other dinoflagellates, and we formed a collaboration to see if we could detect symbiont sex on reefs,” Howe-Kerr said.

“In genomic datasets of coral dinoflagellates, researchers would see all the genes coral symbionts should need to reproduce sexually, but no one had been able to see the actual cells in the process,” said Correa, an assistant professor of biosciences. “That’s what we got this time.”

The discovery follows sampling at coral reefs in Mo’orea, French Polynesia, in July 2019 and then observation of the algae through advanced confocal microscopes that allow for better viewing of three-dimensional structures.

“This is the first proof that these symbionts, when they’re sequestered in coral cells, reproduce sexually, and we’re excited because this opens the door to finding out what conditions might promote sex and how we can induce it,” Howe-Kerr said. “We want to know how we can leverage that knowledge to create more genetic variation.”

coral figure under the sea — A coral of the type studied by scientists at Rice University is protected by dinoflagellates (inset), algae that turn sunlight into food to feed and protect reefs. The study showed the algae are able to reproduce via sex, opening a path toward accelerated evolution of strains that can better protect coral from the effects of climate change. Inset image by Carsten Grupstra/Rice University; coral image by Andrew Thurber/Oregon State University

“Because the offspring of dividing algae only inherit DNA from their one parent cell, they are, essentially, clones that don’t generally add to the diversity of a colony. But offspring from sex get DNA from two parents, which allows for more rapid genetic adaptation,” Correa said.

Symbiont populations that become more tolerant of environmental stress through evolution would be of direct benefit to coral, which protect coastlines from both storms and their associated runoff.

“These efforts are ongoing to try to breed corals, symbionts and any other partners to make the most stress-resistant colonies possible,” Correa said. “For coral symbionts, that means growing them under stressful conditions like high temperatures and then propagating the ones that manage to survive.

“After successive generations we’ll select out anything that can’t tolerate these temperatures,” she said. “And now that we can see there’s sex, we can do lots of other experiments to learn what combination of conditions will make sex happen more often in cells. That will produce symbionts with new combinations of genes, and some of those combinations will hopefully correspond to thermotolerance or other traits we want. Then we can seed babies of the coral species that host that symbiont diversity and use those colonies to restore reefs.”

The research was supported by the Spanish Ministry of Science and Innovation and the European Community Project (DIANAS-CTM2017-86066-R), a Lewis and Clark Grant from the American Philosophical Society, a Wagoner Foreign Study Scholarship, the National Science Foundation (1635798) and an early-career research fellowship from the Gulf Research Program of the National Academy of Sciences (2000009651).

Read the paper HERE!

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Issue 77 - October 2021

SEVENSEAS Beach Cleanup Event for October 2021

It was a bit hectic with COVID-19 this time. However, we manage to organise our cleanup event on Sunday 7th October 2021. This time, we managed to collect only 74 kilograms of marine debris from the beach which is a bit less than last time.

By undertaking these endeavours, we aimed to make a positive impact on our local environment while raising awareness about the significance of preserving our oceans. You can support us by making a DONATION HERE.

Issue 77 - October 2021

SEVENSEAS Travel Magazine – October 2021 – Issue 77

PADI AWARE Foundation’s Dive Against Debris Highlights Socioeconomic Influences on Debris in Global Study

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PADI AWARE Foundation™ has teamed up with CSIRO, Australia’s national science agency, and Ocean Conservancy, the US-based advocacy non-profit, to highlight the role that socioeconomics plays on global hotspots of common debris items on land and the seafloor. Read more…

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The Florida Keys is one of America’s most popular vacation spots because of its miles and miles of splendid beaches, coral reefs, and shipwrecks that can only be completely explored by water. It is also a home to rich marine ecosystems, a variety of public nature parks and historical sites. Read more…

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Sex & The Symbiont: Can Algae Hookups Help Corals Survive?

A little more sexy time for symbionts could help coral reefs survive the trials of climate change. And that, in turn, could help us all. Researchers at Rice University and the Spanish Institute of Oceanography already knew the importance of algae known as dinoflagellates to the health of coral as the oceans warm, and – Read more…

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Fisheries Interactions More Threatening to Maui Nui Dolphins than Previously Thought

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Ocean Hope Chronicles: The Mid-Ocean Mysteries of Humpback Whales

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SAWFISH NEWS: Seeking Wall for Endangered Sawfish Mural

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Where Are the Fish Going? Unsustainable Fishing Practices Leading to Fishery-Induced Evolution

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Under the Waves with Karim Iliya, October 2021

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Allen Coral Atlas Completes First Global Coral Reef Maps

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Self-Discovery in The Sand By Cath Wallis

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‘Driving’ Innovation to Help Eliminate Plastic Waste

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Zero-Waste Week: The Beauty Brands Reducing Their Plastic & 5 Ways To Be More Eco-Friendly

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The FREE Weekly Conservation Post and Jobs List

Signing up for the free Weekly Newsletter & Jobs List will get you a round-up of upcoming events, webinars, meetings, reports, funding opportunities, photos of the week, and recent postings to the jobs list.

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Since 2004, SEVENSEAS Media has fostered an informal and non-partisan platform to promote understanding of key issues and challenges while building partnerships across an increasingly diverse group of marine conservation professionals and students.

Our mission is to promote communication and build partnerships across the global marine community and to identify and address gaps in the community’s work. SEVENSEAS Media achieves this through multimedia promotion and partnerships. The community consists of a diverse and growing group of participants, including non-governmental organizations, government agencies, foundations, bilateral and multilateral agencies, fellowship programs, independent consultants, and academia/students.

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Feature Destination

Fisheries Interactions More Threatening to Maui Nui Dolphins than Previously Thought

Researchers at Pacific Whale Foundation (PWF), a nonprofit organization protecting the ocean through science and advocacy since 1980, dove deep below the surface in a new study that could revolutionize how researchers evaluate the impact of fisheries interactions on dolphin populations. Using dorsal fin, mouth line and underwater body imagery, the latter a first of its kind for this type of study, researchers found that fisheries interactions on Maui Nui dolphins may be more pervasive than initially thought.

Principal investigator Jens Currie, PWF’s Chief Scientist and co-author oversaw the recently published paper, External Scarring as an Indicator of Fisheries Interactions with Bottlenose (Tursiops truncatus) and Pantropical Spotted (Stenella attenuata) Dolphins in Maui Nui, Hawai‘iwhich used PWF’s long-term historic data on bottlenose and spotted dolphins collected over a 24-year period from 1996-2020. A recent paper citing an apparent decline in bottlenose dolphin population in Maui Nui highlights the importance of PWF’s study in exploring the potential impacts of fisheries interaction to these dolphins.

Abigail Machernis, PWF Research Biologist and lead author of the paper, examined data collected in the Maui Nui region of Hawai‘i, which consists of the islands of Maui, Moloka‘i, Lana‘i and Kaho‘olawe and found 27% of 255 identified bottlenose dolphins and 13% of 374 identified spotted dolphins displayed one or more fishery gear-related scars. Every image in the nonprofit’s extensive photo-ID catalog, was reviewed to identify dolphins with scars on dorsal fins, mouthlines and bodies of dolphins that indicate past interactions with fisheries and fishing gear. The objectives of PWF’s research were (1) to determine the number of bottlenose and spotted dolphins that showed evidence of a fisheries interaction in Maui Nui; and (2) to determine if underwater body images, in addition to the traditionally used dorsal fin and mouthline images, increased detection rates of evidence of fisheries interactions.

Building on established methodology, focused primarily on dorsal fin analysis, researchers used underwater body images to gain a new perspective for assessing fisheries interactions. The inclusion of underwater photo analysis was a game changer, according to Machernis. “Most research literature that examines fisheries interactions look primarily at dorsal fins and we wanted to use all the data we have collected to examine as much of the dolphins’ body as possible for evidence of fishing-gear related scars.”

The study’s innovative approach involves combining individual assessments of dolphins’ dorsal fins, mouthlines and bodies into a single assessment and found the inclusion of underwater imagery increased scar detection rates by 51% for bottlenose dolphins and 40% for spotted dolphins. Using past research on fisheries interactions coupled with forward-thinking research methods, the study is the first to present a standardized approach for using photos of dorsal fins, mouthlines, and underwater body footage into the assessment of fisheries interactions.

“Without documenting real-time interactions or observing physical gear on an animal’s body, photo analysis is the best available proxy for quantifying fisheries interactions,” notes Currie. “There is still more research to be done and we want to make sure we have all the information needed to determine if there is a conservation concern and then work with fishers on a solution if warranted.”

Worldwide, interactions with fisheries have been identified as one of the leading conservation concerns for cetaceans resulting in lethal or non-lethal consequences. The full extent is hard to assess as most entanglements are never observed, but research noted by the International Whaling Commission (IWC) suggests that over 300,000 whales and dolphins die annually due to entanglement in marine debris. This can have a devastating, long-term conservation impact on those populations that are already threatened, in some cases critically.

Past and ongoing research confirms that direct interactions between cetaceans and fishing gear typically transpire in one of two ways: (1) animals unintentionally swim into gear becoming entangled or entrapped or (2) animals deliberately remove fish captured in gear, a behavior known as depredating, and become hooked and/or entangled as a result. Some fishing gear interactions can result in serious injury or mortality from entanglement or ingestion of gear.

These types of interactions occur globally and are likely to increase due to the potential for continued human encroachment on cetacean habitats. Thus, the paper asserts, population-level impacts of fisheries on cetaceans are of great concern and there is a critical need to identify which species interact with which fisheries and the location(s) these interactions occur so researchers can work with fishers to find sustainable solutions.

In short, Machernis concludes that these findings suggest that fisheries interactions are more widespread than we previously thought, and this can have implications on how we manage these near shore island-associated populations. In addition to informing management and conservation actions, the study and paper support outreach efforts targeting recreational and commercial fishers that provide education on best fishing practices when dolphins are present.

“We highly recommend researchers interested in examining the threat of fisheries interactions to dolphins make a concerted effort in the field to collect above-water mouth line and body shots, in addition to underwater footage,” Machernis advises, emphasizing the value of images such as those studied in providing a more accurate analysis of scar detection rates.

PWF’s scientific paper, External Scarring as an Indicator of Fisheries Interactions with Bottlenose (Tursiops truncatus) and Pantropical Spotted (Stenella attenuata) Dolphins in Maui Nui, Hawai‘iauthored by Abigail Machernis, Stephanie H. Stack, Grace L. Olson, Florence A. Sullivan and Jens Currie, is published in Aquatic Mammals and available for review. All Pacific Whale Foundation publications are freely available at PacificWhale.org/research/publications.

To learn more or make a contribution to support PWF’s dolphin research, please visit PacificWhale.org/pacific-whale-foundation/.

About Pacific Whale Foundation

With a mission to protect the ocean through science and advocacy and to inspire environmental stewardship, Pacific Whale Foundation (PWF) conducts Research, Education and Conservation programs. Founded in 1980 as a 501(c)(3) nonprofit organization dedicated to saving the world’s whales from extinction, PWF now solely owns social enterprise PacWhale Eco-Adventures, which offers fee-based programs and services to help support the nonprofit. Combined with memberships, donations, charitable grants and a remarkable group of dedicated volunteers, PWF now reaches more than 400,000 individuals each year through its Maui and Australia offices and research projects in Ecuador and Chile.