The Rich Cold Water Coral Diversity of the Falkland Islands: Stylasterid (lace) Corals of the South West Atlantic

By Dr Narissa Bax


Corals are typically linked in people's minds to tropical locations, yet the Falkland Islands harbor a surprising wealth of cold water coral diversity, notably within the Stylasteridae (lace) coral family. Recently, Dr. Narissa Bax shared insights from her collaborative research on these corals from the Burdwood Bank and Bird Island at the 8th International Deep Sea Coral Symposium in Edinburgh, Scotland. Concurrently, she led a workshop to aid in the development of global metrics to understand these corals in a rapidly changing world.

This article provides an overview of some known species from the South West Atlantic, hinting at the potential findings that await future exploration. The abundant biodiversity of the Falkland Islands' corals underlines the importance of supporting scientific research and discovery. We extend our thanks to the Schmidt Ocean Coalition and the Deep Ocean Observing Strategy (DOOS) for their financial support, enabling Dr. Bax to travel to Scotland, and to the scientists and attendees of the coral symposium, who persist in unraveling the enigmas of deep-sea corals world-wide.

Stylasteridae (lace) corals of the Falkland Islands

Living and working in the Falkland Islands, we are surrounded by rugged beauty above the waves, yet it is beneath the sea surface where some of our most extraordinary residents thrive. Today, I invite you into the enchanting realm of the coral family Stylasteridae, or lace corals.

Lace corals belong to a group of animals known as hydrozoan cnidarians. This might sound complex, but let's break it down into simpler terms. Cnidaria is a group that includes creatures you might be more familiar with, like jellyfish and sea anemones. They all share a few common features like tentacles with tiny stinging cells (used for catching food), and a simple body design that's basically a sac with a single opening.

Hydrozoa, a class under the phylum Cnidaria, encompasses creatures such as the Portuguese Man o' War. Typically, hydrozoans exist in colonies, akin to how bees live in hives. Within these colonies, each individual hydrozoan has a specific role to play, much like the division of labor seen in bee communities. However, these colonies are normally sessile, meaning they are permanently affixed to a spot and do not roam freely.

Now, the lace corals are unique as hydrozoans because they build hard, mineral skeletons, which is a trait more commonly associated with 'true' corals (in the class Anthozoa). These skeletons are what give lace corals their intricate, lace-like structures. Each tiny hole in the skeleton is a home for an individual hydrozoan animal, all living together in a colony - like a neighborhood of tiny jellyfish-like creatures, all housed together in a beautiful, hard-built, lacey high-rise!

My PhD on Stylasteridae corals gave me an in depth understanding of these stunning creatures, supported by the wealth of resources at the Smithsonian Natural History Museum. The images I share today were collected as reference material, but after years of study on these corals, I recognise each species like an old friend when I see them in the SAERI and fisheries specimen and image collections. And, occasionally, I stumble upon these corals unexpectedly adorning local gardens and homes, adding a distinct charm to these spaces. These instances, possibly remnants of a past era, are bittersweet reminders of a time when corals were appreciated differently - as unique mementos brought back by fishing families. Despite their undeniable beauty, as a scientist, I feel a twinge of melancholy at this sight, with concern over the implications of such practices. It is vital to remember that these stunning organisms are not merely decorative items, but intricate living systems crucial to our planet's health. Therefore, while we can admire their aesthetic value, we should refrain from encouraging practices that may inadvertently harm their vital ecosystems.

The South West Atlantic waters are a hotbed of unique biodiversity and I am thrilled to share with you a glimpse into the mesmerising world of these lace corals, their intricate structures, much like an underwater tapestry - these are just some of the species living on the seafloor in the Falklands Conservation Zone:

Image Left: Calyptopora reticulata photographed at the Paris Natural History Museum
Image middle: Sporadopora dichotoma photographed at the Smithsonian Natural History Museum © Narissa Bax, SAERI
Image right: The type specimen of Cheiloporidion pulvinatum, originally described from the South West Atlantic © Narissa Bax, SAERI 
Image Left: Stellapora echinata specimen from the Burdwood Bank, so named because of its star shaped gastropores © Narissa Bax, SAERI
Image middle: Stylaster densicaulis a common by-catch species in the Falklands Conservation Zone © Narissa Bax, SAERI
Image right: A matrix of specimen images photographed at the Smithsonian Natural History Museum including (reading left to right) a) Errinopsis fenestrata, Calyptopora reticulata, Crypthelia formosa, Crypthelia studeri b) Lepidotheca fascicularis, Conopora verrucosa, Crypthelia fragilis, Errinopora cestoporina c) Lepidotheca fascicularis, Inferiolabiata labiata, Crypthelia formosa, Errinopora cestoporina © Narissa Bax, SAERI

Having introduced you to some of the intricate coral species, it is time to take our exploration from the individual creatures to the vibrant habitats where they thrive in the Falklands Conservation Zone, and the locations I presented on at the recent coral symposium in Scotland:

Research case study location: Burdwood Bank

The Burdwood Bank, a submerged plateau south of the Falkland Islands, teems with marine life. This underwater oasis, rich in essential nutrients, serves as a veritable 'supermarket' for a myriad of marine species. From whales and seabirds to various fish, it's a crucial feeding ground where our ocean's favorite inhabitants gather to dine. Recent evidence shows that it's not just the bigger animals that benefit from this productive region; the animals that live on the seafloor - the benthic (bottom dwelling) deep-sea species, like corals - are thriving too.

Among these are the now familiar Stylasterid (lace) corals, and our studies in 2018 and 2019 found these corals in abundance, along with several other coral and sponge species. What's interesting is that these organisms are great at capturing and storing CO2, making them crucial players in seafloor blue carbon research (Bax et al. 2021). Yet, we need more information to make sure we can measure this accurately (Bax et al. 2022). Our recent surveys are helping us understand how much CO2 these underwater communities can store and the potential they hold in slowing down climate change.

Read more about life on the seafloor on the Burdwood Bank here: Beautiful Biodiversity on the Seafloor_March 2022

Research case study location: Mesophotic corals at Bird Island, West Falkland 

What's the mesophotic zone, I hear you ask? Picture the underwater world as a layered cake. The mesophotic zone is the layer between 30 and 150 meters deep, a twilight zone where the sun's rays begin to fade almost completely, yet life continues in abundance. Think of it as the 'middle ground' of the ocean, teeming with fascinating creatures. And this region is vast, stretching over an estimated 50,000 square kilometres in the Falklands Conservation Zone. Yet, much of this underwater realm remains unexplored.

My ambition during my time at SAERI? To hopefully advance exploration of Bird Island, West Falklands, and delve into the complexities of an ecosystem that remains largely untouched by human activity, has never been subjected to fishing, and is under consideration for designation as a marine managed area (a form of marine protected area). This makes our research all the more critical, because the knowledge we gather could serve as a pivotal reference point in establishing effective conservation strategies.

During a 2021 expedition, we observed what appeared to be Errina cf antarctica thriving at depths of 40-50 meters. However, without the collection of specimens for detailed study, it is challenging to confirm this identification. Errina corals, along with other visually similar species, exhibit a broad range of forms (see the image matrix below) and populate - sometimes even coexist - in dense clusters in other geographical regions, such as the Chilean fjords (home to E. antarctica and E. gracilis) and East Antarctica (habitat of E. fissurata, E. laterorifa, E. gracilis, and Inferiolabiata labiata).
Image: Errinopsis reticulum an ecosystem engineer species on the Burdwood Bank

Identification is a fundamental first step, from which our work can extend to understanding the response of this region to ocean acidification, the ongoing decrease in the pH of the Earth's oceans, caused by the uptake of carbon dioxide (CO2) from the atmosphere, which results in the seas becoming more acidic, and other facets of climate change such as ocean warming. We are keen to delve into the age and mineralogy of coral skeletons to understand their response to change over time, especially for Errina corals, which intriguingly utilise a bimineralogy comprising both calcite and aragonite. This characteristic might hint at an unexpected resilience in these corals, potentially equipping them better against environmental stresses - a strategy that may have seen these corals colonise and proliferate in select habitats, like Bird Island, during the last glacial maximum over 20,000 years ago.

Image: Matrix of Errina and similar species photographed at the Smithsonian Natural History Museum including from top left to right a) Errina cheilopora, Cheiloporidion pulvinatum, Errina kerguelensis, Errina laevigata, b) Errina cheilopora, Cheiloporidion pulvinatum, Errina kerguelensis, Errina laevigata c) Inferiolabiata lowei, Cheiloporidion pulvinatum, Errina kerguelensis, Errina lavaegata © Narissa Bax, SAERI
Image left:  Errina gracilis © Narissa Bax
Image middle: An aggregation of Errina antarctica in the Patagonian fjords of Chile, observed at remarkably shallow depths of 8-10 meters. This occurrence is due to the phenomenon of deep water emergence, allowing species in deep waters (below 200 meters) to inhabit the euphotic zone, typically shallower than 50 meters © Mathias Hune
Image above: Errina fissurata from the Patagonian shelf © Narissa Bax

Image left: Dense aggregations of Errina laterorifa and Errina fissurata, with E. gracilis and Inferiolabiata labiata also noted in East Antarctica © Australian Antarctic Division, for comparison see the video footage of Errina sp. corals at Bird Island here: MMA Bird Island Coral Gardens
Image right: Errina laterorifa from the Scotia Arc © Narissa Bax

The coral gardens at Bird Island aren't just beautiful; they are ancient, possibly hundreds of thousands of years old. They are like the great-great-grandparents of the coral world, a testament to the resilience of life even in the harshest conditions. But as our oceans face increasing threats, these coral gardens and the myriad of species they support are at risk. Our continual research strives to highlight the significance of such unique ecosystems and their contribution to climate change mitigation. Preserving exceptional areas like Bird Island, with its array of remarkable species, means upholding the integrity of these last unspoiled sanctuaries for the sake of future ocean health. As we look to the near future, our hope is to explore this region more extensively in an imminent field expedition, furthering our commitment to protect these precious marine ecosystems.

Creating coral metrics to monitor and manage these ecosystems

So, how do we make sure our research on deep-sea stony corals, like Stylasteridae, is uniform and easily understood across the globe? Well, the Global Ocean Observing System (GOOS) is working on it. They are creating a handy guide, called an Essential Ocean Variables (EOV) specification sheet. This sheet will help researchers around the world use the same language when talking about these deep-sea corals.

Why is this important? Just as we need to keep track of temperature, rainfall, and other variables in weather forecasts, we also need to keep an eye on certain features of our oceans. Deep-sea corals are part of these crucial features as they are vital for ocean health and biodiversity.

This initiative aligns with the United Nations' broader effort to make our oceans sustainable. Other groups, like the Deep Ocean Observing Strategy (DOOS), are also helping to coordinate everything from research needs to the tools we have at our disposal to study corals.

What we aim to do with this specification sheet is to make it useful to everyone—researchers, managers of natural resources, policymakers—you name it. We want it to help us all understand deep-sea coral ecosystems better and guide us in taking care of them. It will also help ensure that the information we gather is consistent, no matter who's doing the research, making it easier to work together across different fields.
Thank you to the Deep Ocean Observing System's (DOOS) Deep Ocean Early Career Researcher (DOER) program and the Schmidt Ocean Coalition for providing the funding that made this opportunity possible. Thank you to the John Ellerman Foundation for financing my role at SAERI. I extend my appreciation to Henry Rhul, Leslie Smith, and all the wonderful collaborators who joined us at the 8th International Symposium on Deep-Sea Corals in Edinburgh, Scotland. My sincere thanks go to my co-authors on both presentations, and to the dedicated participants of the coral metrics workshop in our pursuit of establishing an Essential Ocean Variable (EOV). A special note of gratitude to the organisers – particularly Laurence De Clippele and Anna Gebruk, whose assistance with workshop preparations was invaluable, and to Sebastian Hennige who made it all possible.

Image above: Participants at the 8th International Symposium on Deep-Sea Corals, Edinburgh, Scotland. SAERI was a proud sponsor of this event and Dr Bax and former SAERI volunteer (and future marine scientist) Hamish McKee were in attendance representing research in the Falkland Islands on the global stage.
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