Corresponding author: Daniel T. I. Bayley (
Academic editor: Ina M. Sieber
Kelp forests provide many important ecosystem services to people, including mitigating storm damage, cycling nutrients, and providing commercially-harvestable resources. However, kelp forests’ ability to sequester carbon dioxide, and therefore help regulate the climate, has until recently, been overlooked in assessments of the beneficial services they provide. In this study we incorporate updated knowledge on the potential of kelp to sequester ‘blue carbon’, and use the extensive kelp forests of the Falkland Islands as a case study to assess the value of kelp forest to society through multiple associated ecosystem services. Our analysis shows kelp forests provide a highly valuable range of direct and indirect services, which if managed correctly, will continue to benefit people, both now and in the future. The total estimated value of the Falkland Islands’ kelp system is currently equivalent to ~ £2.69 billion per year (or £3.24 million km-2 year-1). However, the true value of the kelp forest surrounding the Falkland Islands is likely to be higher still, given that our estimate does not account for elements such as associated scientific research, tourism, and cultural services, due to the necessary data currently being unavailable. Similarly, the full value of these highly biodiverse ecosystems in supplying habitat and food to a large range of associated species is crucial, yet extremely difficult to fully quantify. This study illustrates the importance of maintaining kelp ecosystems in a healthy state to ensure they continue to supply valuable ecological processes, functional roles, and ecosystem services, including their overlooked role as significant long-term carbon sinks.
European Union represented by European Commission Directorate - General Environment. Pilot Project — Mapping and assessing the state of ecosystems and their services in the outermost regions and overseas countries and territories: Establishing links and pooling resources (reference ENV/2017/CFP/MAES-OR-OCT)
MOVE - Facilitating MAES to support regional policy in Overseas Europe: mobilising stakeholders and pooling resources, GA Nº 07.027735/2018/776517/SUB/ENV.D2
Ecosystem services are "the benefits people obtain from ecosystems” and which improve people's overall well-being (
Kelp forests are mixed assemblages of brown algae from the Order
Globally, coastal and marine vegetation captures and sequesters significant amounts of atmospheric carbon dioxide through natural processes, helping to regulate climate. Kelp forests were previously thought to contribute little to carbon sequestration as this habitat is typically located on rocky substrate, as opposed to the soft sediment surrounding habitats such as seagrass and mangrove forest that is necessary for long-term carbon storage (
Kelp additionally provides a range of other important services. These can originate either directly from the kelp itself or indirectly from the diverse range of species which use the kelp forest for food and habitat, or those which are bio-physically influenced by its presence (
This work aims to quantify and estimate the total value of the ecosystem services associated with the Falkland Islands’ kelp forests, including their value in sequestering carbon dioxide, known as 'blue carbon'. We use a combination of high-resolution satellite-derived kelp habitat extent predictions along with a large dataset of in-situ density measurements to examine the ecosystem service value of these kelp forests. This work builds on previous analyses in this region, showing extensive kelp assemblages (
We used a range of economic valuation techniques to assess the combined ecosystem service value of a mixed
The Falkland Islands, situated in the temperate and sub-polar South Atlantic, comprises two main islands (East and West Falkland) and 776 smaller surrounding islands (Fig.
The Falkland Islands is one of the UK’s 14 overseas territories (UKOTs). As such, if they choose to have the UK’s ratification of the Paris Agreement extended to them along with other UKOTs, they will be included in the UK’s future accounting and reporting on emissions under the UN Framework Convention on Climate Change (
The surrounding marine area covers 463,897 km2 within the Exclusive Economic Zone, and includes both shallow and deep sea regions. The waters and coasts are home to a diverse mix of species (
Current kelp distribution was mapped using image classifications based on Sentinel 1 (band 1) and Sentinel 2 (all 10 m bands) satellite imagery; Shuttle Radar Topography Mission (SRTM) data; and Landsat 8, (band 1) inputs within Google Earth Engine (
All satellite imagery was clipped to the Falkland Island area of interest and a cosine terrain correction was applied to the Sentinel 2 imagery to balance the effects of shadowing and bright surfaces. Cloud masking was also applied. Normalised Difference Vegetation Index (NDVI), Enhanced Vegetation Index (EVI), Normalised Difference Water Index (NDWI), and Geary’s C on Landsat 8’s band 1 (coastal aerosol) were calculated as further metrics for input into the model classifier. Ground-truthing points from in-water survey were additionally included for training and validation of habitat classifiers for Random Forest analysis. For further details on the broad-scale mapping methodology, see
Accurate satellite data for the distribution of
Kelp density was calculated based on field survey data collected from across the Falkland Islands between 2008 and 2016 (Shallow Marine Surveys Group, unpublished data), with a total of 315 surveys conducted between 2008 and 2016 (Fig.
The average net primary productivity (NPP) of
The United Kingdom has now shifted from the direct use of the Social Cost of Carbon (SCC), which estimates lifetime damage costs of carbon to society, to a ‘target-consistent’ approach, based on emissions targets for future climate scenarios and the cost of abatement (
CO2e cost values were applied to current estimates of carbon content and sequestration potential within the Falkland Islands (based on current density and distribution and assuming no future decline in kelp extent or density). It is important to note that the current value of the carbon
Our valuation is based on the replacement cost needed to recreate the function of coastal nitrogen and phosphorus regulation and recycling back to the land, if this natural service did not exist (
We calculated average total fish catch (tonnes) over three years (2015-2017) for all 15 commercially-exploited fisheries within the Falkland Islands, based on government data (
We use the market value of each species (£GBP/metric tonne) to estimate the total value of the kelp system in terms of exploited kelp-associated fish harvest (
We use a non-use valuation technique, based on a historic alginate extraction pilot project in the Falkland Islands. A test plant was established in the 1970s (
As no export industry currently exists, and given the proximity of the Falkland Islands to Chile, we assume the same export value per dry tonne for harvested kelps. Average export price of dry
Modelling outputs using remote sensing data gave an estimated total coverage of kelp forest surrounding the Falkland Islands of 830.1 km2 in 2019 (Fig.
Overall values of
The above seasonal density values resulted in an average of 0.12 million tonnes of CO2e estimated to be stored in standing
Applying the mean productivity value of 985 g C m-2 yr-1 (
The combined total peak estimate of CO2 equivalent carbon stored in standing giant and understorey kelp species within the satellite-derived mapped extent of kelp forest in the Falkland Islands is 0.58 million tonnes. Averaged (central estimate) total sequestration to the deep sea is 0.299 million tonnes of CO2 annually. Based on non-traded high-series carbon dioxide equivalent (CO2e) values (
Coastal algae and seagrass beds were collectively estimated by
Six of the 15 major fisheries within the Falkland Islands were found to be reliant on kelp for some period of their life-cycle, based on current knowledge. This includes the kingclip (
It is important to highlight that while kelp provides habitat directly to these species, the biological and oceanographic influence of kelp to the nearshore environment will also trigger potentially large indirect effects on a range of other species, through trophic links which we are unable to assess fully here.
Based on the
Table
The total estimated value of the assessed ecosystem services which are provided by the Falkland Islands’ satellite-mapped kelp forests in 2020, was ~ £2.692 billion per year (or £3.24 million GBP km-2 year-1). This overall monetary value is constructed using estimated values of both direct and indirect services provided by the kelp system as a whole. Indirect services included atmospheric carbon stored or sequestered to the deep sea by
Nutrient cycling was found to be the most valuable service provided by the kelp ecosystem in terms of monetary value. However, values used to estimate nutrient cycling were not Falkland Islands specific, but rather integrated a broad range of estimates calculated for a range of global habitats (including tropical seagrass) (
After nutrient cycling, the next most valuable service was provided by the fisheries and then the climate-buffering service of carbon sequestration. As expected, carbon standing stock value was quite low relative to the other services (based on current CO2e values), with the total value cycling up and down again seasonally through the year as the kelp grows and dies-back (
In terms of the climate buffering benefit from carbon capture, the study showed that the Falkland Islands likely sequesters 0.299 million tonnes of CO2 annually (at a conservative minimum estimate). This amount represents an additional annual contribution of approximately 0.1% of current UK net emissions (364.1 million tonnes CO2e/year in 2018) towards their Nationally Determined Contribution (NDC) legally committed to through the Paris Agreement. UK’s current NDC commitment is a reduction of 61% from 1990 baseline levels of ~ 601 million tonnes CO2e per year, by 2030 (
This element of the study would benefit from additional research in a number of areas. Firstly, it is important to have long-term data on the annual variation in the extent of kelp forests around the Falkland Islands to quantify trends in abundance and distribution (and the rate of change). More detailed analyses and predictions on depth and density/condition (health) of the kelp would also allow for improved estimates of total biomass and management. This study assumes a consistent density across the distribution and uses known biomass estimates from kelp collected at ~ 5 m only (
Secondly, while smaller kelps such as
Thirdly, a missing element to this valuation study is in the quantification of the amount of carbon already sequestered to the deep sea sediments from the kelp forests over the last centuries. Given current estimates of sequestration rates, this value is likely to be substantial, which should be a consideration of any future deep-sea fishing/extraction/damaging activities in these deep highly-sedimented areas. It is also worth considering the potentially significant additional carbon added to the sequestration pathway through degraded phytoplankton, waste, and carbon immobilised within dead consumer’s tissues (
It is important to note that carbon valuation elements, such as the ‘Social Cost of Carbon’ (SCC) method used to create aspects of the non-market value, is essentially a construct that we as people have applied. Therefore, SCC incorporates a large amount of uncertainty, ethical judgements, political beliefs and regional variation. While SCC is very useful as a tool for conceptualising value and debating cost-benefits of a service for policy-making, it is not an absolute value, and so values will likely change over time as knowledge and perceptions change. Aligned with the variation in possible SCC values, other values which feed into the overall valuation of the carbon market, including the cost of oil, are also variable and are liable to become rapidly outdated.
Licence fees from fisheries which are associated with the kelp forest systems amount to an average annual revenue of £7,049,575 to the Falkland Island Government or £8,493 km-2 of kelp. Within our study, we have only evaluated the harvested commercial catch. Consequently, this estimate of the ecosystem provisioning service does not account for additional non-commercial or unharvested fish which are dependent on the system (which may sustain charismatic tourist-friendly species such as dolphins, penguins or sea lions). The harvest value is also changeable, based on market prices and catch quotas, and different fishery species may become commercially valuable in the future.
Data were limited on the proportion of the population of each fishery that is dependent on the kelp forests, and on the extent to which this habitat’s presence and health will influence the continuation of the fishery. We assume here that, if any aspect of the fisheries’ life-cycle is associated with or influenced by the kelp forest, the fishery is wholly reliant on the habitat, which may not be the case. Furthermore, we have limited information on the complete influence of the kelp inshore environment on surrounding adult or planktonic species, or a complete understanding of the likely complex trophic links which exist. Therefore, more fisheries may be indirectly linked to kelp and this is an area in need of further research.
The greatest individual ecosystem service value comes from kelp’s ability to recycle nutrients and clean coastal waters. Without appropriate management of kelp forest systems, this service may become degraded, lowering the overall water quality surrounding the coasts and reducing productivity in associated fisheries that utilise these nutrients (
If the hypothetical alginate industry were to be instigated in the Falkland Islands, an appropriate management strategy and impact evaluation would be necessary in order to harvest kelp sustainably. This would need to include research into the least damaging harvest times, the extent of impact it would cause, and the optimal method of extraction. Linked to any such work would be a cost-benefit analysis of how this activity would affect the other services shown in this work and the important associated biodiversity. Additionally, in a similar fashion to carbon market values, the market values of harvested kelp-associated fish and kelp itself for the alginate industry, can also rapidly change. This is demonstrated well in the 171% increase in the export value of
Marine systems often hold important cultural, historical or religious values for people which live close to them and rely on their services for their livelihoods or well-being (
In a similar fashion to cultural services, nature-based tourism can bring significant revenue for coastal communities through visitor’s appreciation of an area’s beauty, history or recreation, alongside the associated hospitality businesses. Coral reefs, for instance, are thought to provide a value of nearly US$36 billion, or over 9% of all coastal tourism value in the world's coral reef countries (
The coastal protection provided by natural systems such as coral reefs, mangroves, and seagrass is substantial, reducing wave heights by up to 71% and attenuating water flow (
Finally, as kelp is a foundation species and ecosystem engineer, the ecological and functional role of this habitat and the species which rely on it has been the focus of much scientific research and monitoring. The habitat therefore has value in terms of creation of research grants, associated travel and subsistence expenses within local businesses, and broader value for society through the creation of knowledge. In the northern region of neighbouring Chile, the estimated annual investment, in terms of scientific and applied research, in their kelp systems was US $66,174 annually or US $25,957,253 projected over 10 years (
The Falkland Islands’ kelp system appears to be healthy and stable based on the data currently available. However, a great deal of uncertainty still exists over how this and other kelp habitats globally will fare into the future (
While the majority of the local threats can be managed, uncertainty associated with broader climate-induced impacts on kelp and its associated communities, is likely to be the highest concern over the coming years (
While not directly valued in this study, biodiversity plays a key role in providing the basis of many ecosystem services. Large healthy systems which are highly biodiverse can therefore improve the value of services and the systems are more likely to be sustainable (
This study illustrates that the Falkland Islands’ kelp forests supply a range of valuable services to people, which are important both locally and globally. Thanks to the area's geographical isolation and low population, the kelp system currently appears healthy and stable. If future detrimental environmental changes, such as increased local pollution, introduction of unsustainable fisheries, or rapid temperature rise were to occur, we would expect to see declines in terms of habitat distribution and condition. If the system were to decline on a large scale, the loss of direct ecosystem service benefits to the Falkland Islands and the loss of wider benefits to the world through its indirect services, would be substantial and costly. Close monitoring of habitat extent and active management of local stressors will be key to the long term stability of the system, and ensure continued flow of multiple ecosystems services to society.
The research leading to these results has received funding from the European Union, under the programme Pilot Project - Mapping and Assessing the State of Ecosystems and their Services in the Outermost Regions and Overseas Countries and Territories: establishing links and pooling resources, MOVE Project (MOVE-Facilitating MAES to support regional policy in Overseas Europe: mobilizing stakeholders and pooling resources, grant agreement Nº 07.027735/2018/776517/SUB/ENV.D2,
We acknowledge the contribution to this piece of work made by the IMS-GIS data centre (Falkland Islands) through provision of data. We also acknowledge the Shallow Marine Surveys Group for the collection of the in-situ field data on kelp species density. The habitat models mapping
Mapped distribution of kelp forest (
Diagrams of: A) a typical giant kelp (
Published values of total thallus wet and dry weight, mean population density, and carbon content for
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Spring | Autumn | Spring | Autumn | Spring | Autumn | |
6 ±1 | 8 ± 3 | 5 ± 2 | 5 ± 2 | 0.62 | 0.72 | |
12 ±3 | 12 ± 4 | 17 ± 4 | 21 ± 2 | 8.0 | 1.4 | |
1.62 ±0.44 | 2.23 ± 0.60 | 4.55 ± 1.05 | 5.78 ± 0.75 | 0.8 | 0.14 | |
0.27 ± 0.04 | 0.29 ± 0.12 | 1.04 ± 0.47 | 1.28 ± 0.40 | 1.29 | 0.19 | |
13.7 | 18.3 | 26.6 | 26.0 | 10.0 | 10.0 | |
27.23 ±1.07 | 23.44 ± 1.92 | 22.32 ± 0.69 | 21.21 ± 0.75 | 30.0 | 30.0 | |
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0.64 | 0.72 | 0.64 | 0.72 | 0.29 | 0.25 |
0.05 | 0.05 | 0.15 | 0.19 | 0.07 | 0.01 | |
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39,180 | 40,401 | 123,705 | 161,357 | 57,774 | 8,716 |
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Rounded minimum, average, and maximum estimated values of carbon sequestered from the Falkland Islands kelp forests per year, based on current known distribution and NPP rates of 670-1300 g C m-2 yr-1.
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Minimum | Average | Maximum | |
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0.005 | 0.007 | 0.009 |
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0.013 | 0.019 | 0.025 |
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0.038 | 0.056 | 0.074 |
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0.055 | 0.081 | 0.107 |
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0.203 | 0.299 | 0.3945 |
Indirect value calculations for the nutrient-cycling benefit of Falkland Island kelp systems, based on remote-sensed total area. USD = United States Dollars, GBP = Great British Pounds.
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Total area of kelp (Falkland Islands) | 830 Km2 |
Total area of kelp (Falkland Islands) | 83,009 Ha |
Value of nutrient cycling of seagrass / algae beds (based on 2011 values in USD ha-1, from |
$28,916.00 ha-1 year-1 |
Total value in 2007 USD yr-1 (based on |
$2.40 Billion year-1 |
Conversion from 2007 USD to 2020 USD with inflation (1$ = 1.25$) | $3.00 Billion year-1 |
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£ |
Commercial fisheries of the Falkland Islands (2019/2020). Detailing residency or spawning within Falkland Island kelp systems, 3-year averaged total catch (tonnes), value (sterling) and total annual revenue per species for harvest and licence fees. Kelp-associated species shown in bold with greyed background (* Only a proportion of population, ** only as adults, *** only as larvae).
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Kingclip (Cusk-eel) |
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CUS |
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No | 2,076 | 1,438 | 2,984,809 | 183,724 |
Patagonian scallop |
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ZYP |
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4 | 2,000 | 8,667 | 0 | |
Patagonian squid (Falkland Calamari / Loligo) |
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SQP |
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47,149 | 2,500 | 117,871,667 | 6,375,312 | |
Red cod |
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SAO | No | 2,620 | 405 | 1,061,235 | 146,197 | |
Rock cod (mix species) | PAT |
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12,882 | 405 | 5,217,075 | 64,753 | ||
Southern blue whiting |
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POS | No | 3,505 | 613 | 2,148,361 | 279,589 | |
Austral hake | HKX / HKN | No | No | 238 | 2,182 | 520,043 | 0 | |
Common hake |
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HKP | No | No | 19,996 | 787 | 15,736,590 | 1,427,455 |
Grenadier sp |
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RTX | No | No | 1,992 | 617 | 1,228,858 | 448,415 |
Hoki (whiptail hake / blue genadier) |
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GRM | No | No | 7,487 | 537 | 4,020,340 | 465,414 |
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SQA | No | No | 142,523 | 2,550 | 363,484,958 | 8,549,411 | |
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SQS | No | No | 0 | 1,170 | 0 | 0 | |
Patagonian toothfish |
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TOP | No | No | 1,415 | 11,456 | 16,210,240 | 836,770 |
Skates and rays |
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SRX | No | No | 5,163 | 900 | 4,646,400 | 247,121 |
Other | MZZ/SKX | No | No | 345 | 613 | 211,485 | 360,944 | |
Total | 247,393 | 28,173 | 535,350,727 | 19,385,105 | ||||
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Summary value estimates of services associated with giant kelp forest in the Falkland Islands in 2020. Overall remotely-mapped kelp extent for spatial estimates = 830.1 km2. * Blue carbon stock value given assuming the standing stock protected over ten years and applying the future projected CO2e value. Full values for tourism, scientific research, culture, and coastal protection are still currently data-limited or unknown.
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Blue carbon stock | 0.703 million* | 84,721 |
Blue carbon sequestration | 31.07 million | 37,436 |
Nutrient cycling | 2,400.29 million | 2.89 million |
Associated commercial fisheries value | 126.3 million | 152,177 |
Alginate industry (non-use) | 64.19 million | 77,337 |
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Supplementary file
Data audit
Summarised data inputs, methods and limitations for each kelp ecosystem service assessed in the Falkland Islands. Additional details on fish licenCe and catch value for commercial Falkland Islands species.
File: oo_482580.docx