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UNCORRECTED PROOF
Ocean and Coastal Management xxx (2017) xxx-xxx
Contents lists available at ScienceDirect
Ocean and Coastal Management
journal homepage: www.elsevier.com
Current state of seagrass ecosystem services: Research and policy integration
A. Ruiz-Fraua, ∗, S. Gelcichb, I.E. Hendriksa, C.M. Duartec, N. Marbàa
aDepartment of Global Change Research IMEDEA (CSIC-UIB), Miquel Marqués 21, 07190 Esporles, Spain
bCenter of Applied Ecology and Sustainability & Laboratorio Internacional en Cambio Global, Facultad de ciencias biologicas, Pontificia Universidad Catolica de Chile, Chile
cKing Abdullah University of Science and Technology (KAUST), Red Sea Research Center (RSRC), Thuwal, 23955-6900, Saudi Arabia
ARTICLE INFO
Article history:
Received 3 May 2017
Received in revised form 19 September 2017
Accepted 1 October 2017
Available online xxx
ABSTRACT
Seagrasses contribute to the maintenance of human wellbeing. However certain aspects of their role as ecosys-
tem service (ES) providers remain understudied. Here, we synthesise the state of seagrass ES (SGES) research
and policy implications. Additionally, we recommend ways in which SGES research can be integrated in to
policy design, by drawing lessons from the case of Blue Carbon (BC). SGES research suffers from three main
biases: a geographical bias, SGES has been restricted to chartered seagrass areas; a type of service research
bias, provisioning and regulating services have received extensive attention while cultural services remain
understudied; a type of discipline bias, the ecological aspects of SGES have been well documented while
economic and social aspects remain in comparison understudied. These are particularly important, as an un-
derstanding of the social and economic considerations of the provision of ES is fundamental to facilitate its
integration into policy frameworks. Lessons drawn from the operationalization process of BC show the re-
occurrence of certain aspects that have enabled the integration of BC into policy. These aspects are grouped
under 4 different categories. From the analysis of these elements we draw lessons that could facilitate the op-
erationalization of other ecosystem services and their incorporation into management policy frameworks.
© 2017.
1. Introduction
Ecosystems provide essential goods and services supporting hu-
man health, livelihoods, wellbeing and survival, these have been
termed ecosystem services (ES)(MEA, 2005). Over the last two
decades the ecosystem services concept has emerged as a major
framework for discussing social-economic-ecological interactions,
sparking growing interest in both research and policy arenas (Braat
and de Groot, 2012). The debate on ES and their value to humans
was initiated by a first attempt at quantifying the global value of
ES (Costanza et al., 1997). The momentum of the ES concept in-
creased subsequently with the publications of the United Nations' Mil-
lennium Ecosystem Assessment report in 2005 (MEA, 2005) and The
Economics of Ecosystems and Biodiversity report in 2010 (TEEB
Foundations, 2010). These international initiatives highlighted the re-
lationships between ecology and economy, the importance of ES and
the consequences of ecosystem changes for human wellbeing.
Valuation approaches have been crucial in revealing the value of
ES to humans and in their integration into policy. Although the value
of ecosystems to human wellbeing has many dimensions -sociocul-
tural, ecological and economic- and can be expressed in a range of
units (e.g. energetic, land, time), monetary units have been predom-
inantly chosen above the rest. This choice has often been criticised
as some consider that this approach implies the “commodification”
of nature (McCauley, 2006; Gomez-Baggethun and Ruiz-Perez, 2011)
∗Corresponding author.
Email address: aina.ruiz@gmail.com (A. Ruiz-Frau)
arguing that nature should be valued by its intrinsic value and not by
human allocated utilitarian values. Nevertheless, the use of monetary
units represents a pragmatic choice as it resonates with dominant po-
litical and economic views and serves best to communicate to differ-
ent audiences (de Groot et al., 2002; Daily et al., 2009).
Ocean and coastal ecosystems have been estimated to contribute to
more than 60% of the total economic value of the biosphere (Costanza,
1999; Martinez et al., 2007; Costanza et al., 2014). Yet, despite their
importance, data and methods to assess ocean and coastal ecosystem
services are lagging behind those of terrestrial systems (Barbier, 2012;
TEEB, 2012), especially when it comes to mapping, modelling and
valuating ES (Barbier, 2012; Maes et al., 2012; Liquete et al., 2013).
The absence of detailed spatial information on habitat distribution and
the difficulties in quantifying both functions and processes in the ma-
rine environment are considered the main causes for these differences
(Maes et al., 2012).
Within coastal systems, seagrasses are key components that pro-
vide crucial ecosystem services. Seagrasses occur along the shores
of all continents (except Antarctica) to a maximum depth of 50 m
(Hemming and Duarte, 2000). Seagrasses contribute to the protec-
tion of coastal areas by protecting the shoreline (Boudouresque et al.,
2016), diminishing wave energy and trapping sediments (Ondiviela
et al., 2014), providing important nursery areas for a range of fish,
shellfish and crustacean species (de la Torre-Castro and Ronnback,
2004; Jackson et al., 2015; Whitfield, 2017), regulating the cycling
of nutrients (Costanza et al., 2014) and playing a significant role in
the global sequestration and burial of carbon (Kennedy et al., 2010;
Fourqurean et al., 2012; Duarte et al., 2013a), among others. Al-
though no comprehensive data on the global distri
https://doi.org/10.1016/j.ocecoaman.2017.10.004
0964-5691/© 2017.
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2 Ocean and Coastal Management xxx (2017) xxx-xxx
bution of seagrasses exists, the most commonly used estimates in the
literature use a lower estimate of 150,000 km2and a high estimate of
600,000 km2(Duarte, 2005; Nellemann et al., 2009; McLeod et al.,
2011). Regrettably, despite their ecological and societal importance,
it is estimated that seagrasses are being lost globally at rates of about
5–7% year−1. It is also estimated that only in the last seventy years one
third of seagrass coverage has been lost (Orth et al., 2006; Waycott et
al., 2009). The increased knowledge on the important role played by
seagrasses in the capture and storage of carbon (Duarte et al., 2005)
has led to the proposal that seagrasses together with mangroves and
saltmarshes systems can significantly contribute to climate regulation
and should be part of climate change mitigation policies (McLeod et
al., 2011; Nellemann et al., 2009). Carbon sequestered and stored by
these systems has been termed Blue Carbon (BC) (Nellemann et al.,
2009). BC is currently being considered into regional and national en-
vironmental management policies, offering an opportunity to analyse
aspects that have enabled the successful integration of this specific
seagrass ES into international policy. In other words, the success story
of BC provides the opportunity to identify those elements that have
led to the operationalization of the ES concept.
Here we synthesise the state of seagrasses ecosystem services
(SGES) research and policy implications. Our purpose is to: (1) under-
take a systematic evaluation to assess the temporal evolution and state
of research on SGES, (2) identify key topics on SGES that are yet to
be addressed by the research community, and (3) recommend ways in
which SGES research can be better integrated into policy design, by
drawing lessons from the case of BC. A main goal of this evaluation
is to identify critical research gaps that need to be incorporated into
future research agendas to enable the operationalization of the ES con-
cept to support the sustainability of seagrass meadows.
2. Methodology
2.1. Literature search
We compiled studies on seagrass ES published in the peer-re-
viewed literature between 1864 and 16.06.2016 using Web of Science.
Document type was restricted to article or review. Grey literature and
non-English publications were omitted from the search. Since a con-
siderable number of publications relevant for SGES focussed on eco-
logical functions or on socioeconomic aspects without mentioning the
term service, which was introduced in the late 1980's, we conducted
two searches using different sets of keywords. One search focused
on seagrass ecosystem services and the other on seagrass ecosystem
functions. The first search included those studies which contained the
terms seagrass* AND “ecosystem service*” in the title, abstract or
keywords. This search resulted in a total of 165 documents. To as-
certain the relevance of the studies, abstracts of the 165 records were
screened. For those studies in which the abstract was not sufficient to
determine the study content, the full text of the article was assessed.
Articles (62%) were excluded if they were either not related to SGES
or if they used the term ecosystem service only as justification for
the study without assessing SGES. The remaining 62 studies were re-
tained for further analyses. Services were classified according to the
classification established by The Economics of Ecosystems and Bio-
diversity (TEEB) (Brink et al., 2009).
Information on the main characteristics of the studies was ex-
tracted: publication year, perspective (ecological, economic, social,
mixed), analysis type (quantitative, qualitative, conceptual, mixed),
number and type of services assessed, type of data (primary data, re-
view data, model data, proxy data, mixed sources), spatial scale (lo-
cal, subnational, national, supranational, continental, global, labora-
tory experiment) and geographical coordinates. It was considered that
a paper adopted an ecological perspective when it focused on mea-
suring ecological functions or ecosystem properties, an economic per-
spective when the study focused on the estimation of use or non-use
values of SGES and/or their associated benefits in monetary terms and
a social perspective if the paper focused on the values people attrib-
uted to SGES and/or their associated benefits.
The second search was performed to obtain publications on the
seagrass functions underlying each of the services attributed to sea-
grasses: food provision, gas and climate regulation, disturbance pre-
vention, lifecycle maintenance, nutrient removal, leisure and pharma-
ceutical benefits. The search terms used for the different services are
detailed in Table 1.
A total of 1551 records were obtained, which abstracts were
screened in order to quantify the number of relevant studies within
each ecosystem function category (Table 1). Studies were included in
the analysis only when the seagrass function under study was assessed,
studies which only mentioned a particular seagrass function in the ti-
tle, abstract or keywords without including some type of quantitative
or qualitative analysis in the main body of the article, were excluded.
A list of all the articles included in the analyses is available as SI.
Additionally, to analyse the case of BC and discuss the elements
that enabled its integration into policy a search for peer-reviewed
and grey literature was performed. Peer-reviewed literature was re-
trieved using the search term “blue carbon” in Web of Science be-
tween 1864 and 16.06.2016. Document type was restricted to article
or review. This search resulted in a total of 180 documents. Abstracts
were screened to ascertain their relevance. Articles were excluded if
they were not related to BC in marine or coastal ecosystems. A to-
tal of 73 articles were retained for further analysis. Grey literature
was obtained through specific BC repository web sites such as the
bluecarbonportal.org.
Table 1
Search terms used in the evaluation of papers on seagrass functions underlying the pro-
vision of services.
Service
Search terms:
Seagrass* AND …
N
results
% relevant results
(N)
Food provision Fisheries 578 14% (84)
Gas & climate
regulation
“carbon storage” OR
“carbon burial” OR
“carbon sequestration”
OR
“carbon stock” OR
“carbon sink”
72 67% (48)
Disturbance prevention “coastal protection” OR
“coastal erosion” OR
“particle trapping” OR
“particle retention” OR
“wave attenuation” OR
“flow modification”
160 45% (72)
Lifecycle maintenance nursery OR
“feeding ground*”
585 45% (265)
Nutrient removal “nutrient sink” OR
“nutrient removal”
105 32% (34)
Leisure “leisure” OR
“recreation”
43 6% (3)
Pharmaceutics pharmaceut* 8 88% (7)
Total number of
articles
1551 513
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Ocean and Coastal Management xxx (2017) xxx-xxx 3
3. Results
3.1. Seagrass ecosystem services
The term ecosystem service related to seagrasses was first used in
scientific publications in 1997 by Costanza et al. in a paper where ma-
rine and terrestrial ES were economically valued, although it was not
until 2000 (Duarte, 2000) when a publication specifically focused on
SGES was published, almost 20 years after the first peer-reviewed sci-
entific publications on general ecosystem services appeared in 1983
(Ehrlich and Mooney, 1983; Myers, 1983). The use of the term SGES
increased exponentially since then, approximately 63% of the studies
assessed any of them (Fig. 1A). The annual rate of increase of pub-
lications on SGES is similar to that of marine and coastal ecosystem
services (MCES) and general ES (Fig. 1B). At present, publications
on SGES represent 2% of publications on general ES and 19% of pub-
lications on MCES, with an annual rate of increase of 4% and 11%
respectively since 1998. Publications on SGES represent 2.3% of pub-
lications on the field of seagrass ecology and biology but this percent-
age has changed over the last two decades, increasing at an annual rate
of 26% (Fig. 1C).
The approach of 63% of the studies included some type SGES
quantification (Fig. 2A), most were of an ecological nature (45%),
the rest adopted an economic (21%) or mixed (21%) perspective.
Mixed studies generally offered a combination of ecological and eco-
nomic valuations. In general, qualitative studies (13% of the total) of-
fered a social perspective of the value of seagrasses for local commu-
nities, 75% of these studies adopted either a purely social perspective
or a combined social-ecological approach. A small proportion of the
records (11%) included in the evaluation focused on the development
of novel conceptual frameworks that included SGES in their struc-
tures.
Almost 50% of the studies collected their own data, 19% were
based on data from previous studies, 16% presented data derived from
models and the rest used data from mixed sources.
In general, studies did not focus on the assessment of a single
ecosystem service but rather assessed multiple services, the average
number of which was 2 per paper. Approximately 21% of the pa-
pers focused on seagrasses as a food provisioning habitat, most stud-
ies on this area adopted a social valuation approach such as in the
assessment of the importance of seagrasses as low tide gleaning and
artisanal fisheries areas for local communities (Table 2). Regulat-
ing services received the most attention (65% of the studies), fol-
lowed by supporting services (42%) (Fig. 2B). Cultural services con-
versely have remained understudied (19% of the studies assessed cul-
tural services). Within the regulation category, the role of seagrasses
in climate regulation through the sequestration and storage of carbon
Fig. 1. Temporal evolution of publications on seagrass ecosystem services (SGES); (A) total number of publications containing the term SGES and number of real SGES publica-
tions (those assessing SGES in some form); (B) Annual rate of increase of publications on ES in general, marine and coastal ES (MCES) and SGES; (C) Proportional annual rate
of increase of publications on SGES relative to that of ES in general, MCES and general publications on seagrasses. Dashed lines in panels B and C indicate the fitted regression
equations between the natural log of the corresponding cumulative number of publications and time, i.e. the increase rate of publications, which is the slope of the fitted equation
multiplied by 100, is shown next to each dashed line. Searches for MCES and ES in general were performed through Web of Science using the search terms (“ecosystem service*”
or “environmental service*”) and (“marine” or “sea” or “ocean”) for MCES and (“ecosystem service*” or “environmental service*”) for ES in general.
Fig. 2. (A) Distribution of seagrass ecosystem services (SGES) studies according to study type and approach adopted; (B) Distribution of SGES studies according to service type.
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4 Ocean and Coastal Management xxx (2017) xxx-xxx
Table 2
Number of studies published on the different ecosystem services provided by seagrasses
and proportions of ecological, economic and social studies for each of them. Total per-
centages do not add to 100% since some studies assessed more than one ES at a time.
N
Ecological
(%)
Economic
(%)
Social
(%)
Mixed
(%)
Provision
Food 9 22 33 22 11
Raw materials 4 75 50 50
Regulation
Gas & climate regulation 22 59 14 23
Coastal protection 15 33 27 20
Bioremediation of waste 3 33 33 33
Support
Lifecycle maintenance, habitat &
gene pool protection
17 71 12 18
Water condition 9 44 22 11
Cultural
Research & education 4 25 50 25
Recreation & tourism 6 17 33 17 17
Cultural heritage & identity 2 50 50
Total (%) 50% 21% 6% 27%
has received the most attention (35%), followed by their contribution
to the protection of coastal areas by reducing wave energy and stabil-
ising the sediment (24%). In the supporting services category, most
attention has been focused on the importance of seagrasses as nursery
areas for juvenile fish species (27%). Research on the maintenance of
good water quality has centred on their role in nutrient cycling, espe-
cially nitrogen (N) and phosphorous (P) (15%).
For provisioning, regulating and supporting services most studies
have focused on the ecological assessment of the services, while their
economic and social aspects, such as their contribution to coastal pro-
tection for local communities, have received less attention. Only a
small portion of articles assessed seagrasses as providers of cultural
services (Table 2).
Geographically, empirical studies on SGES have mainly focused
on North America, Europe, the southern coast of Asia and Aus-
tralia-Oceania (Fig. 3). In North America, where the highest number
of studies has been recorded (12), studies were mainly of an ecological
nature (58%). Ten studies were located around European coasts, half
of them adopted an economic approach for the assessment of SGES.
A total of 7 studies were recorded in Asia, 71% assessed SGES from
an ecological perspective while the rest adopted a combination of an
ecological-economic-social approach. Few studies were recorded for
South America, the West and South coasts of Africa or the northern
coasts of Europe. A total of 14 studies adopted a more general per-
spective on SGES without referring to specific geographical locations,
drawing conclusions with global applications.
3.2. Seagrass ecosystem functions
The search focusing on seagrass ecosystem functions (SEF) under-
lying the provision of services retrieved a total of 513 publications.
This figure was 8 times greater than the number of publications on
seagrasses explicitly mentioning the term “service” (Fig. 1, Table 1).
With the exception of publications on the nursery role played by sea-
grasses, which started in 1978, publications on the functions of sea-
grasses started circa 1990, almost 10 years before the term “seagrass
ecosystem service” was first used (Fig. 4).
Publications that would qualify as nursery service, on the provision
of food and habitat and inventories of juvenile and adult stages of fish
and shellfish species on seagrasses have by far received the greatest
attention (Fig. 4). Since 1978, 265 studies on this topic have been pub-
lished; this represents fifty-one per cent of the total number of publi-
cations on SEF collected for this evaluation. Seagrasses have also re-
ceived particular attention as food provisioning areas for humans, with
a focus on the adult stages of fish and shellfish species associated with
seagrass meadows. In particular, studies focussed on their importance
for small-scale fisheries and their role as a source of biomass for fish-
eries, as a considerable number of commercial species spend part of
their life cycle in seagrass meadows (Jackson et al., 2015).
Over the past ten years there has been a significant increase in pub-
lications on the role of seagrasses in coastal protection, the seques-
tration and storage of carbon and their function in nutrient removal
of nutrients from the water column (Fig. 4). A steady increase in pa-
pers on coastal protection has occurred since year 2000 with an an-
nual rate of increase of 21%. Papers on this topic have mainly fo-
cused on the effects of seagrass meadows on wave attenuation (35%
of publications) and buffering sediment erosion (19%). Approxi
Fig. 3. Geographical and disciplinary bias of seagrass ecosystem services studies. Dots indicate the location of studies done at specific sites; the rest of studies adopted a global or
general approach to SGES (histogram on Southern Ocean).
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Ocean and Coastal Management xxx (2017) xxx-xxx 5
Fig. 4. Temporal evolution of publications on the seagrass functions underlying the pro-
vision of services. Numbers in brackets represent the average increase in the annual rate
of publications.
mately 17% of the publications considered the subject from a more
general perspective considering all the different factors that play a role
in the protection and maintenance of the coasts.
Publications on the removal of nutrients from the marine environ-
ment have mainly (94%) focused on plant nutrient dynamics (uptake,
the fate of nutrients in seagrass tissues) and sediment nutrient fluxes
and stocks at short time scales (≤1 year). Only few (6%) studies as-
sessed long-term nutrient burial in seagrass meadows (Mateo et al.,
1997; Gonneea et al., 2004). The annual average number of publica-
tions is low, less than two publications per year. Yet, the effort allo-
cated to assess nutrient dynamics in seagrass meadows varied over the
last 3 decades, growing at 30% yr−1 during the 90's, slowing down to
4.3% yr−1 between years 2002 and 2011 and with only 2 publications
on the topic found between 2012 and 2016 (Fig. 4).
Very few studies were found on the pharmaceutical applications
of compounds extracted from seagrasses. Seven publications were re-
leased between 2005 and 2016, on the anti-inflammatory, antioxi-
dant, immunostimulatory and anti-tumour properties of certain sea-
grass substances.
3.3. Blue carbon
Peer-reviewed scientific publications on the carbon cycle functions
of seagrasses, including carbon sequestration, storage and sink ca-
pacity were initiated in 1995 (Fig. 4), although Smith already high-
lighted the important role of marine macrophytes in general as car-
bon sinks in 1981 (Smith, 1981). Twelve studies were published be-
tween 1992 and 2008, at a modest average rate of 1.3 publications
per year. However, over the past eight years (2009–2016) the num-
ber of publications has quadrupled, with an average annual publica-
tion rate of 5 papers. This increase in publication numbers has co-
incided with the release of a United Nations landmark report high-
lighting the role of seagrasses, tidal saltmarshes and mangrove sys-
tems, which the authors termed Blue Carbon (BC) habitats, as in-
tense carbon sinks (Nellemann et al., 2009). The first peer-reviewed
publication to use the term BC appeared in 2011 (McLeod et al.,
2011), since then the publication rate of seagrass BC has increased ex-
ponentially. Between 2011 and 2016, almost 80 publications on BC
(including seagrasses, mangroves and saltmarshes) have been pub-
lished in ecology, management and policy related scientific journals.
The interest in and relevance of the role of BC is reflected on the
rapid growth of publications, which has experienced an annual in-
crease rate of 85%. Approximately 42% of the total number of pub-
lications on BC focused on seagrasses. Of those, 67% adopted
an ecological perspective, 9% an economics perspective, 6% a combi-
nation of the previous two and 24% focused on the policy aspect and
the integration of BC into management.
4. Discussion
4.1. Evaluation of seagrass ecosystem services research
The field of seagrass ecosystem services research is a relatively
novel research area, initiated after Costanza et al. (1997) ranked sea-
grasses amongst the most valuable biomes on Earth. However, spe-
cific research into seagrass ecosystem services is a relatively novel
program that appeared around 2008, following an almost complete
void in addressing SGES in peer-reviewed journals. This might be
partly attributable to the fact that academics focusing on seagrass re-
search seldom write about their findings adopting an ES framework.
Similar patterns can be observed in publications on marine and coastal
ES (Liquete et al., 2013) or on ES in general. We identified here sev-
eral important knowledge gaps in the assessment of SGES. Three main
information biases have been detected, namely a geographical bias, a
service bias and a disciplinary bias.
Geographically, studies on SGES have mainly, but not exclusively,
concentrated along the coasts of North America, the southern coast
of Asia and the coasts of Australia-Oceania, leaving great portions
of coastal areas virtually un-assessed, this is comparable to the find-
ings in Nordlund et al. (2016). There is a need to expand existent re-
search into the coastal areas of Southeast Asia, the eastern and western
coast of South America and the West coast of Africa in order to ob-
tain a more accurate picture of the global magnitude of ES provided
by seagrasses. These areas mainly coincide with unsurveyed areas for
which the extent of seagrass coverage is largely unknown (Duarte et
al., 2013a). Thus, it seems that the geographical bias in SGES research
is heavily linked to uncertainties on the regional extent of seagrass
meadows. So far, limitations in the use of remote sensing tools have
precluded the reliable estimation of seagrass cover. However, a re-
cent review on the application of remote sensing techniques to sea-
grass ecosystems reveals substantial advances in seagrass detection,
assessment of areal coverage, distribution, mapping and the detection
of the extent of biomass changes (Hossain et al., 2015). The mapping
of currently unsurveyed seagrass areas and the development of a crit-
ical number of SGES assessments around the world would allow the
estimation of the global magnitude of SGES provision and how these
maybe affected by different climatic, conservation and management
scenarios.
Our analysis revealed an unbalance in the type of services as-
sessed. Regulating and provisioning services have received consider-
able attention (37% and 63% of the total number of publications, re-
spectively) and although there are still important knowledge gaps, the
amount of existing information on services such as carbon sequestra-
tion, coastal protection and seagrasses as fisheries or nursery areas is
sufficient to allow SGES to be integrated into policy frameworks.
There has been a clear tendency towards the assessment of the
ecological aspects of SGES and the functions underpinning them. In
terms of coastal protection services, efforts have been directed to-
wards demonstrating the role of seagrasses as providers of coastal pro-
tection (Ondiviela et al., 2014). Morphologically, seagrasses are flex-
ible, especially compared to other coastal vegetation like salt marshes
and mangroves. Therefore, their impact on wave attenuation and sed-
iment accretion would be limited compared to stiffer vegetation types
(Bouma et al., 2005). However, they play a major role in reduc-
ing coastal erosion and in trapping and retaining of eroded sedi-
ment (Gacia and Duarte, 2001; Madsen et al., 2001),
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6 Ocean and Coastal Management xxx (2017) xxx-xxx
which is still poorly quantified. Sediment accretion, even over longer
timescales, can play a role in prevention of flooding, relevant for cli-
mate change adaptation at the current rate of sea level rise (Borsje et
al., 2011). It has been shown that seagrasses cannot always provide
adequate coastal protection services and their risk reduction services
will be context dependent (e.g. geomorphology, hydrodynamics, con-
servation state). Hence, coastal protection services cannot be readily
extrapolated across coastal locations and should be quantified at the
site level (Ondiviela et al., 2014).
The carbon sequestration and storage services provided by sea-
grasses (Blue Carbon, BC) has also been the focus of increasing re-
search efforts. The realization in 2005 that seagrass ecosystems are
globally-significant carbon sinks (Duarte et al., 2005), coinciding with
the publication of the Millennium Ecosystem Assessment and fol-
lowed by the appearance of the term BC in 2009 (Nellemann et al.,
2009), provided a substantial momentum for the focus on seagrass
ecosystems as carbon sinks. Recent findings have identified them as
intense carbon sinks that can store up to 25 to 132 gCm−2 yr−1, ex-
ceeding the sequestration capacity of rainforests, and hold that carbon
over millenary time scales (Kennedy et al., 2010; McLeod et al., 2011;
Fourqurean et al., 2012; Duarte et al., 2013b, 2013c). However, there
are still uncertainties that need to be addressed. To fully comprehend
the magnitude of the carbon sink capacity of seagrasses it is neces-
sary to understand carbon stocks and burial rates over different time
scales, the fate of carbon exported from meadows, the variability in
sink capacity and the fate of carbon stocks following disturbance and
seagrass loss (Duarte et al., 2013a). Nevertheless, despite these knowl-
edge gaps there is sufficient understanding on the mechanisms under-
pinning the sequestration and storage of seagrass BC and evidence that
the restoration and conservation of BC habitats can be effective strate-
gies for climate change mitigation (Marba et al., 2015). Collectively,
the scientific knowledge of the role of BC is sufficiently robust to en-
able the integration of BC into policy frameworks. Therefore, a sound
scientific understanding of the ecological processes that support the
provision of ecosystem services is crucial to allow operationalization.
The analysis shows that cultural services associated to seagrasses
have remained understudied albeit the fact that they provide substan-
tial opportunities for recreation, artistic inspiration, research and edu-
cation (Garcia Rodrigues et al., 2017). The assessment of cultural her-
itage and identity values is also of particular importance, especially
around coastal rural communities that tend to depend to some ex-
tent on the services provided by seagrasses (de la Torre-Castro and
Ronnback, 2004; Cullen-Unsworth et al., 2014).
The third knowledge gap identified during this evaluation relates
to a disciplinary bias (i.e. scope of the studies) in the assessment of
SGES. Half of the papers adopted an ecological approach in the as-
sessment of SGES, while only 21% and 6% assessed SGES from a
purely economic and social perspective, respectively. However, 27%
adopted a combination of the three disciplines in the assessment of
SGES. There is a need to increase and direct research efforts towards
the assessment of these two aspects of SGES. As an example, infor-
mation on the economic value of the coastal protection services of-
fered by seagrasses remains insufficient. Yet, economic valuation is
fundamental if seagrass ecosystems are to be included in risk reduc-
tion plans as it allows the integration of natural and man-made so-
lutions for coastal protection in hybrid cost-benefit analyses (Bouma
et al., 2014; Spalding et al., 2014). Dewsbury et al. (2016) argue
that existing valuation frameworks for seagrasses are very limited
and incomplete, since models tend to ignore the quality of the mead-
ows and the effect it might have on the provision of services (e.g.
TESSA (Peh et al., 2013), InVEST (Guerry et al., 2012)). Recently
however, a framework for valuation of SGES has been
suggested where ecological and economic relationships and the differ-
ent goods and services provided by seagrass ecosystems can be de-
lineated individually, therefore allowing prediction of how seagrasses
might function under different scenarios (Dewsbury et al., 2016).
There is a need to increase the number of studies focused on the so-
cial valuation and importance of SGES for different types of commu-
nities. This study evidenced the lack of knowledge on this particular
area of SGES assessments, the shortage of information on the social
relevance of ES seems to be a common deficiency in the assessment
of ES in general, not being only restricted to SGES (Liquete et al.,
2013; Thomas, 2014). Social aspects are particularly relevant in cases
of ES marketization as the governance and perceptions of the demand
and supply of ES are critical elements for their success (Gelcich and
Donlan, 2015). Social aspects might be especially complex in the case
of marine and coastal areas as they are subject to different types of
tenures, management and ownership rights that differ from those on
land (e.g. open access, coastal community rights, customary access to
fishing grounds) both in developed and traditional societies (Hastings
et al., 2012). These unique characteristics require the expansion of cur-
rent social research in order to comprehend the governance systems
around marine and coastal ecosystem services in general and on sea-
grass ecosystem services in particular. A major bottleneck in the social
valuation of SGES is the insufficient public awareness on seagrasses
(Cullen-Unsworth and Unsworth, 2016). This insufficient knowledge
weakens the foundations for societal appreciation of SGES.
4.2. Blue carbon example
The examination of the story of Blue Carbon (among others
Gordon et al., 2011; Herr and Laffoley, 2012; AGEDI, 2013; BCP,
2015) indicates the reoccurrence of aspects that might play an impor-
tant role in facilitating the integration of BC into policies. We argue
that crucial aspects for this integration have been: (i) the existence of
a critical threshold of scientific knowledge regarding the capture and
storage of carbon, as indicated here; (ii) the involvement of interna-
tional non-governmental organizations and agencies in the develop-
ment of BC initiatives and demonstration projects; (iii) the analysis
of ways to operationalize BC into policy frameworks and the de-facto
incorporation through pioneering examples and (iv) the integration of
BC into finance mechanisms.
In contrast to the underrepresentation of social and economic stud-
ies on the diverse range of SGES, in the case of BC for coastal vege-
tated habitats the development of a significant and growing number of
BC demonstration projects by a range of countries and organizations
around the world has greatly contributed to bridge the existing gap in
social and economic research. Demonstration projects have not only
shown how the incorporation of carbon and other ES values into local
and national financial markets and coastal management plans can en-
sure the long-term protection of BC ecosystems but they also highlight
the direct benefits for communities living in vulnerable areas from cli-
mate change related threads (e.g. flood prevention, erosion control)
(Rao et al., 2012; GEF IW:LEARN, 2015; Livelihoods, 2015). Two
examples of demonstration projects are the Blue Forests project and
the Livelihood Funds. The Blue Forest programme is a four-year mul-
timillion project implemented by UNEP, which aims at pushing the
BC (or blue forest) concept from theory to practical application. Pro-
ject activities started in 2014 and are under way in Indonesia, Mada-
gascar, Mozambique, Ecuador and the United Arab Emirates (GEF
IW:LEARN, 2015). The Livelihood Funds project focuses on the pro-
tection of vulnerable areas and communities from climate change
UNCORRECTED PROOF
Ocean and Coastal Management xxx (2017) xxx-xxx 7
related threads through the restoration of coastal vegetated habitats.
This initiative has already restored close to 17000 ha of mangroves
which are expected to offset around 1.2 millions tonnes of carbon
while protecting local communities from coastal erosion (Livelihoods,
2015).
The execution of this range of BC demonstration projects has been
partly possible through the interest, involvement and financial support
of international agencies and organizations such as IUCN, CI, UNEP,
FAO, IOC, UNESCO,1or Wetlands International. The financial sup-
port and interest of these NGO's and agencies has been crucial in the
global acknowledgement of the importance of vegetated coastal habi-
tats as ES providers. Examples of publications by these organizations
are landmark reports such as the publication in 2009 of the UNEP re-
port “Blue Carbon: A rapid response assessment” (Nellemann et al.,
2009), where the term BC was coined, and the importance of BC habi-
tats highlighted as significant elements in climate change mitigation.
Likewise, the publication of a Blue Carbon Initiative report outlining
options to include BC into policy (Herr and Laffoley, 2012) has facil-
itated the integration of BC into several policy frameworks (AGEDI,
2013; NOC, 2013; CCPR and NRWG, 2014). Abu Dhabi's Blue Car-
bon Demonstration project (AGEDI, 2013) serves as an example for
the incorporation of BC in national policy frameworks, as BC has been
integrated into Abu Dhabi's National Biodiversity Strategies and Ac-
tion Plans, National Performance Indices, National Climate Change
programmes and urban development plans (AGEDI, 2013). In the US,
NOAA (National Oceanographic and Atmospheric Administration) is
developing guidance to incorporate ecosystem services, and BC in
particular, into federal policies by changing the way policies are im-
plemented to include the carbon services of habitats (Pendleton et al.,
2013; Sutton-Grier et al., 2014). On a practical level, in April 2013 the
White House released the National Ocean Policy Implementation Plan
(NOC, 2013) where carbon capture and storage is included as one of
the important services provided by coastal ecosystems. More recently,
in October 2014 as part of the Priority Agenda on Enhancing the Cli-
mate Resilience of America's Natural Resources (CCPR and NRWG,
2014) released by the US Council on Climate Preparedness and Re-
silience, NOAA and FWS (Fish and Wildlife Service) established the
identification and support of key restoration projects that can increase
coastal BC sinks. These examples offer the initial steps of the integra-
tion of an important ES into policy frameworks that will eventually
conduct towards the maintenance of coastal vegetated habitats.
One might argue that some of the crucial elements that have en-
abled the integration and operationalization of BC, as opposed to the
rest of SGES, (i.e. bridged gap in social valuation studies, execu-
tion of demonstration projects and involvement and support of in-
ternational agencies) have only been possible through the existence
of one crucial element which is missing for the rest of ES, that is,
the existence of a financial framework that has enabled the marke-
tization of BC. Currently, two main options exist for the marketiza-
tion of BC, financing through the UNFCCC (United Nations Frame-
work Convention on Climate Change) and the integration into alterna-
tive finance mechanisms such as voluntary carbon markets. However,
1International Union for Conservation of Nature (IUCN), Conservation
International(CI), United Nations Environment Program (UNEP), the Food and
Agriculture Organization (FAO), the Intergovernmental Oceanographic
Commission (IOC), the United Nations Educational, Scientific and Cultural
Organization (UNESCO).
most financing mechanisms only include mangrove ecosystems in
their frameworks. In order to promote the inclusion of the rest of
BC ecosystems (i.e. saltmarshes and seagrasses), non-forested marine
and coastal systems should be included in their regulations (Wylie
et al., 2016). Additionally, an option that might further incentivise
the protection and restoration of these ecosystems could be the cre-
ation of a framework that would allow the marketization of other ser-
vices besides BC. Some SGES such as the contribution of seagrasses
to fisheries production are already embedded within financial mar-
kets through the commercialisation of fish. Other services however,
e.g. coastal protection or nutrient removal, which benefits are expe-
rienced at local scales (in opposition to the global benefits of carbon
sequestration) and might not be as easily tradable (as in the case of
fish) might need alternative mechanisms to facilitate their operational-
ization. Mechanisms such as cost-benefit analyses (CBAs), where not
only economic but also sociocultural valuations of ES would need
to be included, could become necessary elements within legal frame-
works for any actions that might affect the integrity of the environ-
ment. Such instruments are already part of national environmental
guidelines in countries like Norway (NGA, 2016) and could promote
the integration and operationalization of the ES concept. However,
CBAs should only be part of an array of different mechanisms to fully
capture the value of ES, as the value of some services such as so-
cio-cultural services, might not be easily reflected through the use of
this particular tool. Their use in combination with frameworks like
Multi-Criteria Decision Analysis (MCDA) frameworks could deliver
a broader set of ES values, including those related to sociocultural ser-
vices (Saarikoski et al., 2016).
5. Conclusion
The operationalization of SGES will most likely go through the
fulfilment of the three knowledge gaps identified in this evaluation
(i.e. geographical, type of service and discipline biases). There is a
need to expand SGES research into areas such as the coasts of South
America, Southeast Asia and the West coast of Africa. The lack of in-
formation on SGES is strongly linked to the incomplete information
on the current global extent of seagrasses. Provisioning and regulat-
ing services have received extensive attention while fewer research ef-
forts have been dedicated to cultural services. Similarly, the ecologi-
cal aspects of SGES have been well documented while the economic
and particularly the social aspects of SGES remain understudied. The
analysis of the operationalization process of BC has shown that one of
the aspects where BC is substantially further in comparison to marine
and coastal ES research is the understanding of the social aspects asso-
ciated to the provision and demand of services which has been mostly
achieved through demonstration projects performed in different parts
of the world. Research into the highlighted areas will be fundamental
to the acknowledgement of the significance of the benefits of SGES
for human wellbeing and will thus facilitate their integration into pol-
icy frameworks.
The analysis of the operationalization of BC has shown crucial fac-
tors that have enabled BC integration into policy frameworks, which
could be used as a model for the operationalization of services de-
rived from other ecosystems. A sound understanding of the ecological
processes underpinning the service; the involvement of international
agencies; the development of projects that demonstrate not only the
ecological but also the economic and social benefits of maintaining the
provision of ES and the existence of marketization mechanisms might
be fundamental pieces in the integration of ES into policy.
UNCORRECTED PROOF
8 Ocean and Coastal Management xxx (2017) xxx-xxx
Acknowledgements
The authors would like to genuinely thank the contribution of the
anonymous reviewers whose suggestions greatly improved the quality
of the present publication.
Funding: this study was funded by the EU FP7 OPERAs (contract
no. 308393).
Appendix A. Supplementary data
Supplementary data related to this article can be found at https://
doi.org/10.1016/j.ocecoaman.2017.10.004.
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