Tag Archives: ocean acidification

‘Ghost’ nannofossils and resilience

Here are the ‘ghosts’,

Microscopic plankton cell-wall coverings preserved as “ghost” fossil impressions, pressed into the surface of ancient organic matter (183 million years old). The images show the impressions of a collapsed cell-wall covering (a coccosphere) on the surface of a fragment of ancient organic matter (left) with the individual plates (coccoliths) enlarged to show the exquisite preservation of sub-micron-scale structures (right). The blue image is inverted to give a virtual fossil cast, i.e., to show the original three-dimensional form. The original plates have been removed from the sediment by dissolution, leaving behind only the ghost imprints. S.M. Slater, P. Bown et al / Science journal

A May 19, 2022 news item on phys.org makes the announcement (Note: A link has been removed),

An international team of scientists from UCL (University College London), the Swedish Museum of Natural History, Natural History Museum (London) and the University of Florence have found a remarkable type of fossilization that has remained almost entirely overlooked until now.

The fossils are microscopic imprints, or “ghosts”, of single-celled plankton, called coccolithophores, that lived in the seas millions of years ago, and their discovery is changing our understanding of how plankton in the oceans are affected by climate change.

Coccolithophores are important in today’s oceans, providing much of the oxygen we breathe, supporting marine food webs, and locking carbon away in seafloor sediments. They are a type of microscopic plankton that surround their cells with hard calcareous plates, called coccoliths, and these are what normally fossilize in rocks.

Declines in the abundance of these fossils have been documented from multiple past global warming events, suggesting that these plankton were severely affected by climate change and ocean acidification. However, a study published today in the journal Science presents new global records of abundant ghost fossils from three Jurassic and Cretaceous warming events (94, 120 and 183 million years ago), suggesting that coccolithophores were more resilient to past climate change than was previously thought.

….

A May 20, 2022 UCL press release (also on EurekAlert but published May 19, 2022), which originated the news item, provides more detail and quotes from some very excited academics,

“The discovery of these beautiful ghost fossils was completely unexpected”, says Dr. Sam Slater from the Swedish Museum of Natural History. “We initially found them preserved on the surfaces of fossilized pollen, and it quickly became apparent that they were abundant during intervals where normal coccolithophore fossils were rare or absent – this was a total surprise!”

Despite their microscopic size, coccolithophores can be hugely abundant in the present ocean, being visible from space as cloud-like blooms. After death, their calcareous exoskeletons sink to the seafloor, accumulating in vast numbers, forming rocks such as chalk.

“The preservation of these ghost nannofossils is truly remarkable,” says Professor Paul Bown (UCL). “The ghost fossils are extremely small ‒ their length is approximately five thousandths of a millimetre, 15 times narrower than the width of a human hair! ‒ but the detail of the original plates is still perfectly visible, pressed into the surfaces of ancient organic matter, even though the plates themselves have dissolved away”.

The ghost fossils formed while the sediments at the seafloor were being buried and turned into rock. As more mud was gradually deposited on top, the resulting pressure squashed the coccolith plates and other organic remains together, and the hard coccoliths were pressed into the surfaces of pollen, spores and other soft organic matter. Later, acidic waters within spaces in the rock dissolved away the coccoliths, leaving behind just their impressions – the ghosts.

“Normally, palaeontologists only search for the fossil coccoliths themselves, and if they don’t find any then they often assume that these ancient plankton communities collapsed,” explains Professor Vivi Vajda (Swedish Museum of Natural History). “These ghost fossils show us that sometimes the fossil record plays tricks on us and there are other ways that these calcareous nannoplankton may be preserved, which need to be taken into account when trying to understand responses to past climate change”.

Professor Silvia Danise (University of Florence) says: “Ghost nannofossils are likely common in the fossil record, but they have been overlooked due to their tiny size and cryptic mode of preservation. We think that this peculiar type of fossilization will be useful in the future, particularly when studying geological intervals where the original coccoliths are missing from the fossil record”.

The study focused on the Toarcian Oceanic Anoxic Event (T-OAE), an interval of rapid global warming in the Early Jurassic (183 million years ago), caused by an increase in CO2-levels in the atmosphere from massive volcanism in the Southern Hemisphere. The researchers found ghost nannofossils associated with the T-OAE from the UK, Germany, Japan and New Zealand, but also from two similar global warming events in the Cretaceous: Oceanic Anoxic Event 1a (120 million years ago) from Sweden, and Oceanic Anoxic Event 2 (94 million years ago) from Italy.

“The ghost fossils show that nannoplankton were abundant, diverse and thriving during past warming events in the Jurassic and Cretaceous, where previous records have assumed that plankton collapsed due to ocean acidification,” explains Professor Richard Twitchett (Natural History Museum, London). “These fossils are rewriting our understanding of how the calcareous nannoplankton respond to warming events.”

Finally, Dr. Sam Slater explains: “Our study shows that algal plankton were abundant during these past warming events and contributed to the expansion of marine dead zones, where seafloor oxygen-levels were too low for most species to survive. These conditions, with plankton blooms and dead zones, may become more widespread across our globally warming oceans.”

For the curious, there is also a May 19, 2022 American Association for the Advanced of Science (AAAS) news release about this discovery in Science, the journal they publish.

Here’s a link to and a citation for the paper,

Global record of “ghost” nannofossils reveals plankton resilience to high CO2 and warming by Sam M. Slater, Paul Bown, Richard J. Twitchett, Silvia Danise, and Vivi Vajda. Science 19 May 2022 Vol 376, Issue 6595 pp. 853-856 DOI: 10.1126/science.abm7330

This paper is behind a paywall.

Glass sponge reefs: ‘living dinosaurs’ of the Pacific Northwest waters

Glass sponges in Howe Sound. Credit: Adam Taylor, MLSS [Marine Life Sanctuaries Society]

One of them looks to be screaming (Edvard Munch, anyone?) and none of it looks how I imagined an oceanic ‘living dinosaur’ might. While the news is not in my main area of interest (emerging technology), it is close to home. A June 1, 2020 University of British Columbia news release (also on EurekAlert) describes the glass sponge reefs (living dinosaurs) in the Pacific Northwest and current concerns about their welfare,

Warming ocean temperatures and acidification drastically reduce the skeletal strength and filter-feeding capacity of glass sponges, according to new UBC research.

The findings, published in Scientific Reports, indicate that ongoing climate change could have serious, irreversible impacts on the sprawling glass sponge reefs of the Pacific Northwest and their associated marine life – the only known reefs of their kind in the world.

Ranging from the Alaska-Canada border and down through the Strait of Georgia, the reefs play an essential role in water quality by filtering microbes and cycling nutrients through food chains. They also provide critical habitat for many fish and invertebrates, including rockfish, spot prawns, herring, halibut and sharks.

“Glass sponge reefs are ‘living dinosaurs’ thought to have been extinct for 40 million years before they were re-discovered in B.C. in 1986,” said Angela Stevenson, who led the study as a postdoctoral fellow at UBC Zoology. “Their sheer size and tremendous filtration capacity put them at the heart of a lush and productive underwater system, so we wanted to examine how climate change might impact their survival.”

Although the reefs are subject to strong, ongoing conservation efforts focused on limiting damage to their delicate glass structures, scientists know little about how these sponges respond to environmental changes.

For the study, Stevenson harvested Aphrocallistes vastus, one of three types of reef-building glass sponges, from Howe Sound and brought them to UBC where she ran the first successful long-term lab experiment involving live sponges by simulating their natural environment as closely as possible.

She then tested their resilience by placing them in warmer and more acidic waters that mimicked future projected ocean conditions.

Over a period of four months, Stevenson measured changes to their pumping capacity, body condition and skeletal strength, which are critical indicators of their ability to feed and build reefs.

Within one month, ocean acidification and warming, alone and in combination, reduced the sponges’ pumping capacity by more than 50 per cent and caused tissue losses of 10 to 25 per cent, which could starve the sponges.

“Most worryingly, pumping began to slow within two weeks of exposure to elevated temperatures,” said Stevenson.

The combination of acidification and warming also made their bodies weaker and more elastic by half. That could curtail reef formation and cause brittle reefs to collapse under the weight of growing sponges or animals walking and swimming among them.

Year-long temperature data collected from Howe Sound reefs in 2016 suggest it’s only a matter of time before sponges are exposed to conditions which exceed these thresholds.

“In Howe Sound, we want to figure out a way to track changes in sponge growth, size and area and area in the field so we can better understand potential climate implications at a larger scale,” said co-author Jeff Marliave, senior research scientist at the Ocean Wise Research Institute. “We also want to understand the microbial food webs that support sponges and how they might be influenced by climate cycles.”

Stevenson credits bottom-up community-led efforts and strong collaborations with government for the healthy, viable state of the B.C. reefs today. Added support for such community efforts and educational programs will be key to relieving future pressures.

“When most people think about reefs, they think of tropical shallow-water reefs like the beautiful Great Barrier Reef in Australia,” added Stevenson. “But we have these incredible deep-water reefs in our own backyard in Canada. If we don’t do our best to stand up for them, it will be like discovering a herd of dinosaurs and then immediately dropping dynamite on them.”

Background:

The colossal reefs can grow to 19 metres in height and are built by larval sponges settling atop the fused dead skeletons of previous generations. In northern B.C. the reefs are found at depths of 90 to 300 metres, while in southern B.C., they can be found as shallow as 22 metres.

The sponges feed by pumping sea water through their delicate bodies, filtering almost 80 per cent of microbes and particles and expelling clean water.

It’s estimated that the 19 known reefs in the Salish Sea can filter 100 billion litres of water every day, equivalent to one per cent of the total water volume in the Strait of Georgia and Howe Sound combined.

Here’s a link to and a citation for the paper,

Warming and acidification threaten glass sponge Aphrocallistes vastus pumping and reef formation by A. Stevenson, S. K. Archer, J. A. Schultz, A. Dunham, J. B. Marliave, P. Martone & C. D. G. Harley. Scientific Reports volume 10, Article number: 8176 (2020) DOI: https://doi.org/10.1038/s41598-020-65220-9 Published 18 May 2020

This paper is open access.

Almost finally, there’s a brief video of the glass sponges in their habitat,

Circling back to Edvard Munch,

Courtesy of www.EdvardMunch.org [downloaded from https://www.edvardmunch.org/the-scream.jsp]

Here’s more about the painting, from The Scream webpage on edvardmunch.org,

Munch’s The Scream is an icon of modern art, the Mona Lisa for our time. As Leonardo da Vinci evoked a Renaissance ideal of serenity and self-control, Munch defined how we see our own age – wracked with anxiety and uncertainty.

Essentially The Scream is autobiographical, an expressionistic construction based on Munch’s actual experience of a scream piercing through nature while on a walk, after his two companions, seen in the background, had left him. …

For all the times I’ve seen the image, I had no idea the inspiration was acoustic.

In any event, the image seems sadly à propos both for the glass sponge reefs (and nature generally) and with regard to Black Lives Matter (BLM). A worldwide conflagration was ignited by George Floyd’s death in Minneapolis on May 25, 2020. This African-American man died while saying, “I can’t breathe,” as a police officer held Floyd down with a knee on his neck. RIP (rest in peace) George Floyd while the rest of us make the changes necessary, no matter how difficult to create a just and respectful world for all. Black Lives Matter.

Café Scientifique Vancouver (Canada) talk on August 28th 2018: Getting the message: What is gene expression and why does it matter?

Here’s more about the latest Café Scientifique talk from an August  22, 2018 announcement received via email,

Our next café will happen on TUESDAY, AUGUST 28TH at 7:30PM in the back
room at YAGGER'S DOWNTOWN (433 W Pender [St., Vancouver]). Our speaker for the
evening will be DR. KATIE MARSHALL from the Department of Zoology at
UBC [University of British Columbia]. Her topic will be:

GETTING THE MESSAGE: WHAT IS GENE EXPRESSION AND WHY DOES IT MATTER?

Many of us think that DNA is like a light switch; you have a particular
sequence of base pairs or a particular chromosome, and these directly
cause a large change in biological functioning. But the truth is that
any given gene can be up or downregulated through a dizzying array of
biochemical “dimmer switches” that finely control how much that
particular gene is expressed. Understanding how this works is key to
answering questions like “How does a sequence of base pairs in DNA
become a whole organism?” and “Why is it that every cell has the
same DNA sequence but different function?”. We’ll chat about the
advances in computing needed to answer these questions, the importance
of gene expression in disease, and how this science can help us
understand social issues better too.

I wasn’t able to find out too much more about Dr. Katie but there is this profile page on the UBC Zoology Department website,

The long-term goal of my research is to understand how abiotic stress filters through physiology to shape species abundance and distribution. While abiotic stressors such as temperature have been used very successfully to predict population growth, distribution, and diversity of insect species, integration of the mechanisms of how these stressors are experienced by individuals from alteration of physiology through to fitness impacts has lagged. Inclusion of these mechanisms is crucial for accurate modelling predictions of individual (and therefore population-level) responses. My research to date has focused on how the impact of frequency of stress (rather than the duration or intensity of stress) is a superior predictor of both survival and reproductive success , and used insect cold tolerance as a model system.

At UBC I’ll be focusing on the cold tolerance and cryobiology of invertebrates in the intertidal. These organisms face freezing stress through the winter, yet remarkably little is known about how they do so. I’ll also be investigating plasticity in cold tolerance by looking for interactive effects of ocean acidification and community composition on thermal tolerance.

Enjoy!