Thomas Wernberg
Exploring the Ecology and Future of Kelp Forests
How Seaweeds Captured Wernberg’s Imagination
Thomas Wernberg is a name synonymous with kelp forests and temperate marine ecology. Growing up on a small island in the Baltic Sea, his connection to the ocean was forged early, through family outings and fishing with his dad. Though initially drawn to political science, a twist of fate led him to the world of marine biology, where he stumbled upon a unique fascination with seaweeds. Reflecting on this unexpected discovery, Wernberg recalls, “I just thought, this is amazing! We’ve got these big underwater plants here that seem to be super important, but no one's really interested in them, they just consider them weeds”.
A Transformative Semester
During his university degree, Wernberg spent a semester studying marine biology in Tromsø, northern Norway, where he had the opportunity to dive into the kelp forests for the first time. This experience was transformative. He describes the sensation of swimming through a seaweed forest, observing how different organisms use different parts of the multi level habitat that’s created. From the tiny creatures living inside the holdfast and the epiphytes growing on the stipes, to the fish swimming through the canopy. The kelp forest was a living, breathing ecosystem that captured his imagination. "I had a really amazing experience up there - almost like a revelation of how important these kelp forests were, and just the thrill of swimming through the kelp forest. I said - I want to go diving in kelp forests for the rest of my life."
the start of a lifelong passion
Wernberg's relationship with seaweeds quickly became much like a birder's pursuit of rare birds. He developed a "bucket list" of seaweeds he wanted to find. The initial interest was in classification - a quest to identify and understand the 150 or so species that were accessible to him. This led to what became a large herbarium collection of species right from the beginning of his interest in seaweed. Acquiring a comprehensive knowledge of the local species proved to be the start of a lifelong passion that would shape his career and take him around the world.
Kelp’s Value and Influence
GEAK workshop participants in Arendal, Norway
His work has led to the formation of the GEAK (Global Ecosystem services Assessment for Kelp forests) network which compiles solid information on the different types of ecosystem services that kelp forests provide. "We’ve been documenting the many ways kelp forests benefit people globally—from their contributions to Indigenous cultures and carbon sequestration to the diverse ecosystem services they provide. We are now at the point where we’re beginning to truly understand just how extensive and profound their influence is on human societies, and that’s incredibly exciting," he explains.
Wernberg's research delves into the multifaceted values that kelp forests provide, looking beyond their ecology to also consider their cultural and economic significance. "One of the things I find super, super exciting at the moment is all of this work we have been doing on the values of kelp forests", Wernberg shares. He emphasises the broad values of kelp forests including contributions to recreation, wellbeing, fisheries, water quality, and carbon sequestration.
the journey of kelp and carbon sequestration
Kelp is also important to carbon cycling and involved in drawdown and long term storage of carbon dioxide. Thomas describes the process of whole plant dislodgement, fragmentation, and the seasonal growth cycle of kelp, particularly focusing on species like golden kelp Ecklonia radiata on the Great Southern Reef.
"It does vary… from species to species, from place to place. But if we look at, for instance, golden kelp on the Great Southern Reef, then whole plant dislodgement is probably about 10 percent of the (carbon) export”.
Wernberg delves into the details of how kelp contributes to carbon sequestration, explaining how the majority of the biomass exported consists of fragments that can eventually end up in the deep sea. "The majority of the biomass that's exported are bits and pieces essentially, most of it is fragments of various sorts and sizes, and that enters the marine environment and gets broken down even further," he says. This process is vital in the context of climate change, as it helps in absorbing and sequestering carbon for the long term in a process of natural buffering.
Wernberg and his team are utilising oceanographic models, particle distribution models, and various experiments to track the journey of kelp and its role in carbon sequestration. "Essentially, we're trying to employ a more multidisciplinary approach to try and map the pathway of kelp” Wernberg elaborates, explaining that they are using in situ breakdown and remineralisation experiments, as well as studying microbial breakdown.
Their goal is to understand the rate at which kelp either enters coastal food webs and is returned to the carbon cycle or ends up buried or in the deep sea where its content can remain locked away for extended periods. This research will offer a comprehensive view of kelp's contribution to the global carbon balance and valuable insights into the potential for harnessing this natural process for climate mitigation.
Climate Change and Kelp Forests: A Global Phenomenon
Wernberg’s research has shown how kelp forests are disappearing globally at an alarming rate and are vulnerable to climate stressors such as marine heatwaves. Wernberg emphasises that it's not just from ocean warming but also due to grazing species expanding and migrating and reduction in water clarity, a phenomenon known as coastal darkening.
He describes the visual changes in stressed kelp forests, the susceptibility to fouling, and the detrimental effects of small turf filamentous algae that take over reefs and suffocate the kelp. His insights provide a vivid picture of the challenges faced by kelp forests and the urgent need for conservation.
Marine Heatwave & Loss of WA Kelp Forests in 2010-11
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In the summer of 2010-11 Western Australia experienced an extreme marine heatwave. Driven by a strengthened flow of the Leeuwin Current, which carries warm tropical water south along the coast, and exacerbated by a very hot summer, ocean temperatures soared up to 5°C above normal summer maximum for around 10 weeks.
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This was the warmest period in more than 130 years of temperature recordings and 300 years of ocean temperatures reconstructed from coral cores.
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The marine ecosystem along the west coast responded immediately to the heatwave. There were sightings of big charismatic animals much further south than normal, such as tiger sharks and whale sharks. Little Penguins started to die because they couldn’t feed on the fish they normally eat. Seagrasses died, there were mass killings of fish, and abalone populations collapsed in Kalbarri.
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One of the most prominent effects was the loss of the kelp forest. It was a defining moment in Wernbergs career: entering the water for a dive at Kalbarri expecting to find a familiar underwater seascape of dense kelp, he instead saw a barren reef, devoid of kelp but covered in turf algae packed with sediments. The experience was a shocking example of how quickly ecosystems can change when conditions reach their extremes.
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This marine heatwave was not an isolated incident; it was a warning sign of what would eventually be seen in many other ecosystems and kelp forests around the world. This loss was a tangible, devastating reality that Wernberg and his colleagues witnessed firsthand.
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“Basically, we lost about 40 percent of our kelp forests on the west coast during this heatwave," Wernberg recalls.
The Future of Kelp Forest Research and Restoration
Wernberg's interest also extends to researching the prospects of kelp forest restoration. Restoration aims to reclaim lost habitat, in a resource hungry process that’s in its infancy in marine ecosystems. Acutely aware that restoration at the large scales required cannot be accomplished by scientists alone, Wernberg is working with a team involving industry partners, governmental bodies, and innovative thinkers. He's exploring the potential of using the carbon trading market to fund restoration efforts, aligning ecological imperatives with financial incentives. Collaborations are focusing on carbon accounting mechanisms and carbon credits, creating a framework to support large-scale restoration. Collaboration and innovation is also about developing pioneering new methods to tackle the problem. One such innovative approach is "green gravel", a technique that has the potential to transform kelp forest restoration.
green gravel
The "green gravel" concept emerged from collaborations with Norwegian researchers who were looking to restore sugar kelp in southernNorway. Wernberg explains, "They lost kelp forests around southern Norway in the late 1990s and early 2000s during some exceptionally warm summers, and were looking into ways of restoring their sugar kelp”. Researchers at the Institute of Marine Research in Norway, came up with this idea that maybe it would be possible to seed the sugar kelp onto small rocks and just scatter them out in the environment.
This idea was inspired by the natural growth of sugar kelp on small rocks, leading to pilot experiments and adaptation of the technique for trials in Australia. Building on this work, Wernberg and colleagues founded the Green Gravel Action Group, a growing network of 24 projects testing green gravel to restore kelp forests on 5 continents.
The Challenge of Scalability
The total mapped area of the worlds’ kelp forests that has been degraded and lost is in the order of one to one and a half million hectares. In contrast, the biggest restoration projects currently underway are a couple of hundred to a couple of thousand hectares. With kelp forests in many places declining one or two per cent per year, the current rate of restoration is orders of magnitude away from matching the rate of degradation.
One desirable aspect of green gravel as a restoration technique is its potential for scalability. Wernberg emphasises this challenge, stating, "It's very difficult to see many of the other techniques of restoring kelp forests being able to scale up and restore the truly large areas of kelp forests that have been degraded."
This highlights the urgent need to focus on large-scale restoration, moving beyond the quarter-square-metre plots that most scientists are working on. "We need to upscale, and I think green gravel has potential in that regard. But it's not a silver bullet, we still need multiple approaches to restoration for sure". Green gravel represents a promising step in the right direction, but it will be just one part of a broader toolkit if we are to address the complex and urgent challenge of kelp forest degradation.
“Of course, at the end of the day, restoration is little more than a bandaid on a severed limb. We are treating the symptoms, not the cause of kelp forest decline”, Wernberg explains. “It would be much cheaper and by far more efficient to avoid loss to start with”
Vulnerability of Other Seaweeds
Wernberg's research also explores the vulnerability of other seaweeds, particularly fucoids. He has discovered that some species, having evolved in cooler and more stable times, are now facing increasing threats due to climate change. Interestingly, Wernberg predicts a potential increase in golden kelp in certain areas, at least in the intermediate future, as more climate-sensitive species like fucoids decline.
"I think what we will see over the next couple of decades is that the golden kelp may actually expand in many places because sensitive endemic fucoids are more vulnerable, so they will disappear first, opening up habitat for golden kelp." In the long run, the next 100 years or so, however, golden kelp will also succumb to climate change”.
This shift in seaweed populations is not without its concerns. Current projections suggest that the range of many temperate seaweed species could shrink dramatically, anywhere from 40 percent to total extinction. Wernberg warns, "Some species could potentially go functionally extinct. In Australia, Giant Kelp for example, could disappear." This underscores the complexity of marine ecosystems and the delicate balance that sustains them, highlighting the urgent need for continued research and conservation efforts.
Wernberg’s Favourites
Wernberg's favourite part of the Great Southern Reef lies in Western Australia, particularly around the Albany area and its offshore islands. He's drawn to the region's clear visibility underwater, diverse seaweed species, and the grandeur of its big granite slopes.
He acknowledges the attention often given to golden kelp, but emphasises the importance of recognizing other species that are equally abundant, especially on the more exposed reefs.
Wernberg is particularly drawn to Scytothalia dorycarpa and some of the Cystophera species, appreciating the uniqueness and beauty in the brown seaweeds that are so prolific across the region.
Passion for Fieldwork
Wernberg's fieldwork has taken him to some of the most remote and breathtaking underwater seascapes. Whether diving in the kelp forests of northern Norway or exploring the Great Southern Reef, his experiences in the water have been a vital part of his career.
Wernberg's commitment to fieldwork is also about engagement and inspiration. He sees it as a vital tool to stay connected with the nature he is trying to understand, and for nurturing the next generation of marine scientists. “Unfortunately it is getting harder and harder for scientists and students to get in the water and this poses a significant threat to marine science” Wernberg laments “we are losing our connection to nature on the altar of rules and administration but spending time underwater observing the kelp forests in real time is critical to our ability to ask the right questions”.
His advice to aspiring researchers is resonant and clear: be persistent, consistent, and considered in communication. He emphasises the delicate balance between advocacy and science, urging them to approach their work with purpose and a genuine love for the ocean.
The Great Southern Reef Research Partnership
The Great Southern Reef Research Partnership is a collaboration between universities, management agencies, and NGOs across Australia. This partnership aims to safeguard the Great Southern Reef's critical functions, fisheries, and biodiversity through a whole-of-system approach, aligning scientific endeavours and creating a broader vision that transcends regional differences.
“Our shared scientific fascination with the Great Southern Reef has grown over decades, yet we've often operated in isolation," Wernberg reflects. "Now, through the Research Partnership, we can unite our collaborative efforts from multiple angles, and that is the exciting momentum we need. There is a real need to delve deeper into what binds the Great Southern Reef as a unified ecosystem. It's not about being caught up in the differences among regions, but understanding the inherent similarities that tie us together”.
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