| November 1st, 2023 | Highlights

30 BY 30: HOW TO RESTORE THE KELP FORESTS?

Barbro Taraldset Haugland – Institute of Marine Research (IMR), Norway

A couple of years into the UN Decade of Ocean Science, there is increased focus on restoring blue forests along the coastline. In December, Norway signed the UN Kunming-Montreal Global Biodiversity Framework, where one of the goals is to restore 30% of all destroyed nature by 2030 (known as 30 by 30). But are we ready? Do we have enough knowledge about where and how kelp forests should be restored to achieve long term restoration? And does the legislation really allow for meeting the restoration objectives?

Restoration of kelp forests is neither a new nor innovative phenomenon. The first documented case occurred as much as 300 years ago, in Japan. In 1718, the monk Saint Teiden asked fishermen to throw stones into the waters along the coast where the kelp forest had disappeared,to create a habitat on which the kelp could grow. This is the first documented case of what we today call ‘active restoration’. Today, Japan is the country with the highest number of restoration projects initiated – over 700 between 1970 and 2014. A total of 100 hectares, or 1 km2, of kelp forest has been restored. The numbers demonstrate how labor intensive marine restoration is, and gives a sense of the scale of the challenges that Norway now faces.

Identifying the need for intervention – and how to go about it

Restoration has gained momentum over the past 10 years, with more restoration attempts made during this decade than throughout the rest of history combined. Extensive knowledge has been gathered about what is important to achieve successful kelp forest restoration, as seen in the recent UNEP report, but challenges remain in identifying what type and scale of intervention is needed.

To decide whether restoration is needed, step 1 is to determine for certain that the kelp forest has decreased in the area. This is not necessarily as easy as it sounds. It is often more difficult to confirm if a nature type has decreased in the ocean than on land, partly because monitoring in the sea is much more costly and labor-intensive. The need for restoration is usually more obvious in instances where there has been a human interference with nature, or where larger areas have lost kelp forests, for example as a result of grazing sea urchins.

If there is suspected, but not confirmed, kelp forest reduction, it is vital to start monitoring to detect changes. If possible, you can introduce preventative measures, such as regulation of activities that may negatively affect to ensure that no reduction occurs in the future. Conservation measures will always be cheaper and easier to implement than restoration.

If there is confirmed kelp forest reduction, you can move to step 2: trying to identify the cause. Restoration that is started without knowing the root cause(s) of reduction, only fixes the symptom. If you do not address the cause, you may end up having to repeatedly run active restoration efforts in the same area long term, which is very costly, and in the worst case scenario does not work at all. Some causes can be addressed, such as overfishing or an overload of nutrients (eutrophication). However, when the cause is more frequent marine heat waves and a changing climate, local restoration may not work.

Kelp restoration decision chart from the UNEP report Into the Blue: Securing a Sustainable Future for Kelp Forests (link)

An example of the latter is seen in California, where active restoration of kelp forests has been going on since the 1960s. There, the problem is recurring sea urchins that graze down large parts of the kelp forest. The cause of this is complex, and some of the factors behind it  vary locally. Addressing the root cause has therefore not been an easy task. And as long as the cause of the sea urchin blooms is not addressed and resolved, restoration must be continued indefinitely.

Having determined the root cause of reduction, you can go to step 3: Location location location. Just as in real estate, location is vital. Where within the impacted area you begin restoration has a major impact on your likelihood of succeeding. Proximity to an established kelp forest has proven to be a key success factor. If the effort is carried out more than 1000 m away from an established kelp forest, the chance of succeeding decreases. This is probably due to the fact that the restoration area is supported by spores from the established kelp forest. This also highlights the importance of conserving the kelp forest we already have.

Several active methods have been developed for restoration, such as the use of artificial reefs to create a habitat for kelp to grow on, and transplanting kelp plants seeded on pebbles – a method fittingly named green gravel. The most suitable method for an area will depend heavily on the causes of decline, as well as local environmental conditions. It is therefore not a given that a method that works well in one area will work in a different area. Some of the methods have been tested at several locations, but we still need more evidence of what combinations of methods yield the best results in the short and longer term.

The alternative – letting nature fix itself 

The best way to restore ecosystems is to use nature’s own capacity for self-repair – what we call nature-based solutions. This is what 30 by 30 refers to. Nature-based solutions is a collective term for methods that “mimic” nature, i.e. that are based on natural processes and ecosystems. This also includes a very little labor-intensive method, called “leave it alone”.

Any restoration where humans actively try to fix or repair nature comes with a risk of failure. There are countless examples of this, both from above and below water. Nature and ecosystems are highly complex, and getting a full overview of all the small parts that play a role (i.e., all the animal species, algae, seabed type, nutrients, ocean currents, etc.) and how big a role they play is an almost impossible task. By going in and actively making changes, there will be the risk of one of the parts responding in a surprising way. However, when nature is left alone, it shows a great capability of restoring the ecosystems by itself.

Today, there are 16 marine protected areas established in Norway, and many in the planning process. International studies, including from New Zealand, have shown that restoration requires clear goals, large enough areas, good regulation in line with IUCN criteria, and enforcement. As of today, the regulation in Norway’s protected areas is weak, for example by often allowing fishing, which we know has an impact on kelp forest ecosystems. Marine protected areas can be a good passive method for restoring kelp forests along our coastline, if the regulations limit those human activities that we know affect the ecosystem. 

Sugar kelp forest outside Bergen. Image: NIVA

Upscaling and seeing the bigger picture

Until today, most attempts at restoration globally have been experimental, based on diving, and on a small scale, both in terms of area (1 hectare) and time (a couple of years). Smaller projects – such as the “Tarevokterne” who are helping kelp forests in northern Norway – are certainly important, and part of the solution. At the same time, we need to upscale restoration efforts, which comes with some practical challenges:

A) activities that work on a small scale do not necessarily work when they are upscaled. We need projects that will work on a scale that is relevant to management, i.e., 100 hectares or more, if it is going to have any management value

B) we need a toolkit of methods that are tried and tested, including combinations of methods that work in synergy and in multiple locations according to the cause(s) of the reduction. These include active methods such as seeding kelp plants, artificial reefs and sea urchin removal, but also passive ones, such as regulating fishing and other human activities. 

C) we need simple and cost-effective methods for delivering restoration at scale. Smaller projects often involve dive-based restoration, which is very labor intensive and too expensive for larger-scale projects.

A restoration initiative developed at IMR shows highly promising results to address some of these challenges. Green gravel is perhaps the greatest international success that exists today for active restoration, showing promising results on four continents.

Globally, some large-scale projects,i.e., areas covering over 100 hectares, have succeeded. The first successful large-scale project was carried out in Norway, in a fjord in Finnmark. Here, the kelp forest has come back, showing that large-scale projects are certainly possible, as long as they are well thought out and based on evidence and knowledge.

One final challenge is our approach to restoration as an isolated activity. Most projects only focus on the kelp itself. But the marine ecosystem is complex, and we can neither protect nor restore kelp forests well if we do not include other species that also have a role in the kelp forests. We need to take a holistic perspective to increase the chances of success.

For example, imagine a kelp forest that has been grazed to a barren by sea urchins, it does not necessarily help if we sow kelp seeds or deploy artificial reefs. The new kelp plants will most likely also be grazed. We could include sea urchins in our management plan, and remove them while we sow new plants. This could potentially result in the forest regrowing for a couple of years, but if there are no predators present to control the sea urchin population, there is a good chance it will increase again and graze the forest back to a barren wasteland. If we additionally were to include fishing efforts of predators in the management plan, such as cod and monkfish – fish that eat sea urchins, we start to approach a balanced ecosystem where the kelp forest can survive and thrive over a longer period of time. In a kelp forest, there are obviously many other species that can play important roles, but when we in this scenario move from focusing on one species (the kelp) to four (kelp, sea urchins, cod and monkfish) we drastically increase the chances of success immediately and in the long term.

Global movements, local action 

We still have our work cut out for us when it comes to finding the most efficient methods for expanding restoration. Today, there are several networks (NGOs, citizen science) that work together to exchange knowledge, connect people, and share experiences and motivation. One example is the Kelp Forest Alliance, a site where you can also follow the number of restoration projects taking place around the world.

In Norway, the different methods that can be used to restore an area are managed under different laws (see table for more details). Some activities can be done by anyone, anywhere, over as large or small an area as desired. This largely applies to sea urchins, as sea urchins and other echinoderms (unlike, for example, fish) are not covered by the Animal Welfare Act, but by the Marine Resources Act. In other words, you can pick or crush sea urchins by hand, as Tarevokterne are doing in Tromsø, as long as there is no use of traps or “vacuum cleaners” – the two latter methods must be applied for as it can lead to the collection of other animals as well (i.e. bycatch).

If you want to seed kelp plants, deploy artificial reefs or spread limestone in an area, you need to submit an application for each area you wish to restore. On the whole, this approach makes sense, as actively trying to “fix” nature can end up doing more harm than good. However, as in all cases of regulation, it is important to find a balance between protecting ecosystems from potentially harmful interventions and allowing for productive action.

Summary table of the different laws and regulations associated with kelp forest restoration in Norway (from Verbeek et al. 2021, Restoring Norway’s underwater forests. A strategy to recover kelp ecosystems from urchin barrens. SeaForester, NIVA & Akvaplan-niva)

In 2010, Norway signed an agreement for a 10-year plan to halt the loss of biodiversity, also called the Aichi targets. In 2020, when the deadline passed, none of those goals had been reached. If we are to have a chance of reaching the 30-by-30 goals for restoration, we need to identify the scale and causes of kelp forest reduction, design appropriate interventions, tackle the challenges to upscaling, and reduce barriers for positive and nature based solutions.