wetland ecosystem service values and shrimp aquaculture relationships in can gio, vietnam

Ecological Indicators 46 (2014) 201–213

Wetland ecosystem service values and shrimp aquaculturerelationships in Can Gio, Vietnam

S. McDonough a,*,1, W. Gallardo b, H. Berg c, N.V. Trai d, N.Q. Yen d

aAquaculture and Aquatic Resources Management, Asian Institute of Technology, Klong Luang, Pathumthani, 12120 Bangkok, ThailandbDepartment of Marine Science and Fisheries, College of Agricultural and Marine Sciences, Sultan Qaboos University, OmancDepartment of Physical Geography & Quaternary Geology, Stockholm University, SwedendDepartment of Fisheries Management and Development, Faculty of Fisheries, Nong Lam University, Linh Trung Ward, Thu Duc District, Ho Chi Minh City,Viet Nam

A R T I C L E I N F O

Article history:Received 2 February 2014Received in revised form 9 May 2014Accepted 10 June 2014

Keywords:MangrovesEcosystem servicesEnvironmental valuesAquacultureVietnam

A B S T R A C T

Wetland valuation methods often apply monetary driven approaches that may undermine intrinsicecosystem values. Utilizing a stated preference method, the study identified and mapped localstakeholder ecosystem service values between subsistence wetland and shrimp farmer groups in CanGio, Vietnam. Through focus group choice experiments, ecosystem services correlating to unique priceincrements and cost/benefit tradeoffs between hypothetical intensive aquaculture developments andmangrove conservation scenarios were investigated. Selection outcomes exhibited strong values forecosystem services maintained at the hypothetical natural state (core area pre-intervention 45%, post-intervention 55%; buffer zone pre-intervention 65%, post-intervention 73%). Few respondents selectedthe hypothetical intensive aquaculture development scenario (core area pre-intervention 18%,post-intervention 9%; buffer zone pre-intervention 12%, post-intervention 5%), and instead, mostrespondents avoided the costs and benefits of intensive aquaculture development in preference formaintaining natural ecosystem services. Group deliberations drew out a higher sense of altruism andresponsiveness to intrinsic wetland values that superseded the potential economic gains of aquaculturedevelopments, whereby certain ecosystem services were deemed economically unassociable andirreplaceable for both study groups. The qualitative results expose the difficulties in monetarilymeasuring ecosystem services, highlighting the need to incorporate approaches that integrate theintrinsic values attached to ecosystem services.

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1. Introduction

Ever since (post Vietnam war economic reforms),Vietnam’s wetlands have been, and are still subject to conversionfor monetary gains driven primarily by high export demands forshrimp. Vietnam’s growing shrimp industry has raised environ-mental, economic and social attentions, and despite numerousrestoration projects, high mangrove losses as a result of aquacul-ture development have been reported (World Bank, 1999; WorldAtlas of Mangroves, 2010). In 1976, Vietnam produced around

* Corresponding author at: Aquaculture and Aquatic Resources Management,Asian Institute of Technology, Klong Luang, Pathumthani, Bangkok 12120, Thailand.

E-mail addresses: [email protected] (S. McDonough),[email protected] (W. Gallardo), [email protected] (H. Berg),[email protected] (N.V. Trai), [email protected] (N.Q. Yen).

1 Permanent address: FAORAF, Gamel Abdul Nasser Road, P.O. Box 1628, Accra,Ghana. Tel.: +233 505256401.

http://dx.doi.org/10.1016/j.ecolind.2014.06.0121470-160X/ã 2014 Elsevier Ltd. All rights reserved.

200,000 t of shrimp and in 2011, a significant production increasedwith over 487,000 t covering over 290,000 ha of wetlands wasrecorded on a national level (Wilder and Phuong, 2002; EJF, 2003;FAO, 2011). Unregulated wetland conversion into shrimp farmscombined with detrimental aquaculture practices influencesnatural habitat resiliency and its ability to deliver supporting,regulating, provisioning and cultural ecosystem services definedby the United Nation’s Millennium Ecosystem Assessment (MEA,2005; TEEB, 2010) and exposes stakeholders to different naturaland socio-economic risks. The true long-term outcomes of shrimpaquaculture development costs and benefits are not fully under-stood with shrimp aquaculture development potentially morecostly through its long-term externality costs (Primavera, 1997;Ashton, 2007), than the preservation of wetlands and its delivery ofnatural ecosystem services to local and regional communities,directly and indirectly.

Shrimp aquaculture inputs and outputs are economically drivenand exploitative with little considerations to the long-term

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202 S. McDonough et al. / Ecological Indicators 46 (2014) 201–213

negative environmental outcomes (Rosenberry, 1998; Páez-Osuna,2001; EJF, 2003). However, the economic benefits of shrimpaquaculture should not be disregarded as added capital can boostthe national economy, improve local livelihoods, and aid in ruraldevelopment (Frankic and Hershner, 2003; Gunawardena andRowan, 2005). Vietnam’s aquaculture is poised to intensify asdeclared by Government Decision No. 21, 1998 and GovernmentDecision No. 67, 1999 (EJF, 2003), encouraging aquacultureexpansion at the private level, exposing mangrove wetlands tofuture pressures. Wetland habitats should not be overlooked for asingle industry as they also support other sectors such as tourism,fisheries and sustain rural livelihoods by providing provisioningservices such as plant and animal materials used for housing,medicines, foods, and fuel (Rönnbäck,1999). Unsustainable shrimpdevelopments combined with new challenges such as climatechange and hydropower developments (Hori, 1993; Bakker, 1999)presents the ecosystem service concept as a tangible approach to

Fig. 1. Location of core area and buffer zones where focus group discussions were codistricts. Core area focus groups were conducted in the central areas of Can Gio.

utilize in habitat valuation to better mainstream a more ‘risk-proof’approach in policy development when managing land-alteringindustries, such as aquaculture to be a more proactive industryrather than its typical reactive manner.

Shrimp developments, particularly in Southern Vietnam isoften focus on intense production and are detrimental to thedelivery of ecosystem services (World Atlas of Mangroves, 2010).Can Gio presented a unique location based on its close proximity toHo Chi Minh City and the UNESCO biosphere reserve to examinethe exchanges in conservation and development values. As the corearea is protected there is no imminent threat to the wetland, butintensification and future expansion of shrimp farming activityfrom buffer zone activity will have impacts on habitats.

Utilizing ecosystem services as the core component of thechoice experiment, the study identified and mapped what valueswere placed on wetland ecosystem services in relation to naturalconservation and shrimp aquaculture developments in Can Gio’s

nducted. Shrimp farming is undertaken within buffer zones under the respective

S. McDonough et al. / Ecological Indicators 46 (2014) 201–213 203

socio-economic and biophysical context. Choice experiment focusgroups were conducted in two respondent groups: subsistencewetland users living inside the UNESCO biosphere reserve corearea and shrimp farmers along the reserve’s buffer zone. Focusgroups were utilized as a means for the respondents to discuss anddeclare what ecosystem services they valued individually and as agroup under the different hypothetical scenarios presented. Thestudy objectives were to (1) identify the principal stakeholdersreliant on mangrove wetland ecosystem services, (2) identify whatecosystem services are present, delivered, sustained, and utilizedby these wetland users, (3) identify if and how shrimp aquaculturedevelopments or wetland protection impact ecosystem servicedelivery, (4) map the communal interactions and values placed onmangrove ecosystem services in relation to wetland conservationand aquaculture development drivers, and (5) assess whatinfluences trade-offs and degrees of willingness to accept priceincrements between the different ecosystem service scenariosamongst respondent groups.

2. Material and methods

2.1. Study area and groups

Rich in flora and fauna biodiversity, the UNESCO Can Giobiosphere hosts over 21,000 ha of wetlands with 77 differentmangrove species (UNESCO, 2000). Can Gio’s proximity to Ho ChiMinh City and shrimp farming activity around the buffer zonesmake it an ideal location to examine the anthropogenic values andits relationship to ecosystem services, shrimp aquaculturedevelopment, and wetland conservation. Shrimp farming in CanGio occurs in the transitional buffer zones around the UNESCOreserve where in 2012, four districts were recorded to regularlyconduct shrimp farming (Fig. 1). An Thoi Dong ward hosts around695 operating shrimp farms; Binh Khah, 508; Ly Nhon, 243 andTam Thon Hiep, 68 shrimp farms; in total, Can Gio encompassesaround 1514 officially recorded operational shrimp farms (Can GioAnnual Report, 2011). Key informants from the Can Gio Peoples’Committee, the Can Gio Mangrove Protection Management BoardPark Authority, and Nong Lam University in Ho Chi Minh Cityassisted in identifying respondent groups, providing logistic,linguistic and personnel support in both core areas and buffer

Fig. 2. Steps taken in the focus group activity to deliberate ecosystem service v

zones. Core area respondent groups who mainly live a subsistencelifestyle within mangrove habitats were investigated to tease-outwhat ecosystem services are valued in a more naturally unper-turbed situation with minimal aquaculture developmental influ-ences. Core area groups consisted of three stakeholders groups:artisanal fishers, intertidal small-scale mollusc farmers, and parkrangers. Artisanal fishers comprised of individuals that lived onboats, fishing Can Gio’s tributaries. Most mollusc farmers lived inhouses constructed on intertidal mudflats and cultured mollucsspecies such as Crassostrea gigas, Anadara granosa, and Meretrixlyrata inside the reserve’s core areas. Park rangers consisted ofrangers employed under the Can Gio Mangrove ProtectionManagement Board Park Authority and lived in posts situatedthroughout Can Gio’s core areas. Differences between intensiveand extensive shrimp farming were not made as buffer zonegroups were randomly conducted. The total numbers of respond-ents within the core areas were lower in number due to time,boating costs and personnel constraints. In total, 157 individualsparticipated in the choice experiment, 42 questionnaires distrib-uted with 10 focus groups consisting of 42 participants from thecore area (16 fisher folk, 8 mollusc farmers and 16 park rangers)and 32 focus groups of 118 participants (mostly shrimp farmers) inthe buffer zones.

2.2. Research design

Stated preference methods have been applied throughout theregion to investigate wetland values in Do and Bennett (2005) andThuy (2006). In this study, a series of focus group discussion choiceexperiments identified what ecosystem service utility valuesexisted between the two stakeholders and distinguished thedegree of communal willingness to accept price incrementsbetween the costs/benefits of shrimp development and mangroveconservation efforts. The stated preference technique, rather thanthe revealed preference technique, was applied as it minimizedbiases and allowed for the presentation of hypothetical scenarios,enabling greater content flexibility and comparisons (Hanley andSpash, 2001) between the studied groups. Focus group choiceexperiments (Fig. 2) began with a warm-up exercise whereby threeitems related to wetland habitats (Nypa fructans seed nodule,Pluchea indicus herbs and insect repellents) were presented to

alues in relation to shrimp aquaculture development and wetland protection.


stimulate group discussions on habitat alteration. Warm updiscussions did not contribute to the final datasets and lastedaround fifteen minutes with discussions taking place on itemusage, abundance and frequency of its access. Next, a specificchoice set was presented to the particular respondent groupbeginning the deliberation process. After choices were selectedand discussed, the intervention exercise would be conducted tofurther probe respondent ecosystem service values in relation toshrimp aquaculture and wetland conservation. After the interven-tion exercise, the same choice set was presented to the samerespondents to once again deliberate and discuss the choiceselections, questioning the changes, if any were made. At the end, around up discussion was conducted debating and summarizingwhat has been learned from the discussions. One of the mostimportant aspects of this approach was the empowerment of localcommunities and the opportunity for the respondents to choosethe desired ecosystem service outcomes based on their experi-ences. The respondents’ opportunity to discuss the reasons behindtheir choices made before (pre-intervention) and after (post-intervention) the intervention exercise helped to elicit deeperdiscussions on what communal values were placed on their habitat(see Section 2.3).

2.2.1. Ecosystem service scenarios and price incrementsThe stated preference technique required respondents to

determine their most preferred option from the three differentscenarios presented as ‘states’. These states characterized ecosystemservices delivered in bundles at different proportions (Fig. 3). Thenatural state is representative of an unperturbed habitat withminimal aquaculture developments due to higher conservationefforts. The current state attempts to best represent the localsituation at that specific time for that specific site; a ‘middle ground’that does not reflect intensive aquaculture development or strictwetland protection. The alternative state reflects a landscape shapedby human enterprise and engineering altered for aquacultureproduction at higher intensities resulting in altered habitats foreconomic outcomes. For the sake of the experiment, states were notrevealed during focus groups discussion until the later stages of thetask (during post-intervention choice selections), but were pre-sented as price increments values, pre-intervention. Price incre-ments were placed on each state with the aim to tease out ecosystemservice values in relation to monetary costs when the services arefaced with shrimp aquaculture development pressures or wetlandconservation pressures between the two study groups. Within thesehypothetical states different services and products would bedelivered, some at higher or lower rates and at different pricesdepending on the state and the ecosystem service (see Section 2.3).

Fig. 3. The three states and their ‘bundled’ efficienc

Core area price increments were presented as a hypotheticalgovernment wetland conservation plan whereby communitiespaid an annual community tax. Prior to the choice experiment itwas revealed, through key informant interviews that a 7,000,000VND yearly tax is placed on inhabitants living inside core areas andthis value was used as the current state median value between thealterative and the natural state (Table 1). The alternative statedeclares a hypothetical 25% increase in the communal tax isrequired to manage shrimp farming impacts (e.g., clean upschemes and personnel to regulate developments and practices)placing core area alternative price increments at 8,750,000 VNDannually. The natural state declares that hypothetically highertaxes are placed to maintain more stringent conservation efforts(ranger fees, station construction, maintaining laws, and legis-lations) therefore price increments increases 50% (10,500,000 VNDannually) and as a result, natural ecosystem services are deliveredmore efficiently. Buffer zone price increments were presented asshrimp farming production costs such as feed, anti/probiotics,electricity, labor, and other production expenses. The current stateassumes a median base where production costs are contextual tothe period of the study when discussing with key informants andpilot study shrimp farmers where it was revealed that most CanGio farmers spent around 190,000,000 VND/crop. Based on thisfigure shrimp farming price increments were presented as either amarginal 25% or a 50% increase in production costs relative to thespecific respondent farmers. Consequently the current state waspresented as a “no change” in farming costs state, the alternativestate assumed that higher shrimp production outputs and inputsresulted in higher costs (50% increase in production costs) with theconsequence of ecosystem services delivered at a degraded rate.However, the benefit of higher production per cycle may result ingreater monetary profits were presented as a possible outcome.The natural state presents lower production, but due to a lack ofinfrastructure (electricity, roads, and feed outlets) the costs toacquire the necessary farming products and services are hypo-thetically less accessible resulting in a 25% increase in overall costs.It was stressed to participants that although these scenarios werehypothetical, respondents should try to treat it as real lifeoutcomes. To help devise scenario parameters and gain anunderstanding of the current situation, key informant interviewswith Can Gio People’s Committee and Park Authorities wereconducted before the actual focus groups. After the key informantinterviews, a preliminary field visit to study locations wasconducted to carry out two pilot studies, one each for core areaand buffer zone groups. The pilot study lasted two days andenabled for the adjustment and improvement of the studymethods, helping refine the hypothetical states presented, tested

y conditions presented to the respondent groups.

Table 1Price increment mechanism and effects under their unique states presented to respondent groups.

Priceincrement

Core area Buffer zone

Natural Current Alternative Natural Current Alternative10,500,000 VNDannual tax

7,000,000 VNDannual tax

8,750,000 VND annualtax

25% increase inproduction costs

No changes inproduction costs

50% increase in production costs

Mechanism Increased effortson wetlandconservationprojects outsidecore area.

No changes inconservation efforts.Core areaboundaries remainthe same.

Decreased efforts onwetland protectioninside core area.Private shrimp venturecompensate specificcosts.

Low infrastructure results inhigher prices, middlemanservices, electricity costs,price for fuel to access feed,and seed.

Shrimp farmingmethods andactivity resume asregular.No changes inshrimp farmingmethods.

Increased production intensityresults in higher farming costs,labour, medicines, electricity,logistics, feed and seed costs arethe drivers.

Effects Increased deliveryof naturalecosystemservices andricherbiodiversity.Decreased accessto market goods,reduced localinfrastructure andeconomy.

Some ecosystemservices deliveredwith moderateaccess to marketsoutside core area.

Decrease delivery ofnatural ecosystemservices, area lessbiodiverse with adegraded naturalhabitat.Improvedinfrastructure andintroduction of urbanmarket systems, betteraccess to market goods.

Increased delivery of naturalecosystem services, higherbiodiversity and naturalheritage.Decreased access to marketgoods, reduced localinfrastructure and economy.

Some ecosystemservices deliveredwith moderateaccess to marketsoutside core area.

Decrease delivery of naturalecosystem services, lessbiodiverse and degraded naturalhabitat.Improved infrastructure andintroduction of urban marketsystems.Improved livelihood forsuccessful farmers.


the initial demographic questionnaires, and scrutinizing theecosystem service parameters.

2.3. Choice experiment focus groups and choice grids

Focus groups discussion were conducted with mostly males,not age specific, with a minimum of three to four individuals andwith discussions lasting one and a half hours. The initial task ofeach focus group discussion was to obtain individual demographicinformation (age, monthly salary, education, years of shrimpfarming/living in reserve areas, if they possessed radios/TVs, and ifthey had any children). Discussions were recorded using an audiorecorder for all the respondent groups and later translated fromVietnamese into English. Throughout the study, four differentchoice sets were prepared and presented to four different groupsmatching their context. One choice set for each study group waspresented and explained by the study facilitator. The choice gridswere fabricated from a plastic sheet with a grid drawn onto it withpicture cards used to convey ecosystem service parameters aswritten text would exclude illiterate individuals, hold attentionsbetter and was easier for the facilitator to explain. Images wereplaced on their respective position on the grid and coloured stoneswere used to trace respondent choices, pre and post-intervention.Four stones were given to each individual to place on the choicegrid where each individual had to choose once per row (ecosystemservices) and must consider the conditions of each of the threecolumns (state/price increment) presented. To sum up, eachrespondent had four choices out of a possible twelve; by avoidingor selecting a certain choice, respondents indicated their ecosys-tem services values and the desired outcomes of their environmentand livelihood. The facilitator constantly reminded respondents toconsider price increments and their consequences throughout thediscussions, individually and as a group, promoting groupdiscussion on the topics raised and asking for explanations behindthe choices made and the choices not made.

After selections were made and the reasons behind theselections discussed, the facilitator would then conduct theintervention exercise aimed to stimulate respondents to discusscomprehensively the potential impacts on ecosystem servicesdriven by aquaculture development or wetland conservationefforts. To initiate the intervention exercise, the facilitator would

ask the respondents if they knew examples of how shrimpaquaculture and conservation efforts alter landscapes and ecosys-tem services. If respondents were unable to provide examples anddiscussion was lacking, the facilitator would present a set ofimages, in random order, showcasing three negative (images ofdegraded mangrove habitat, shrimps infected with hepatopancre-atic parvovirus, and urban pollution) and three positive examples(images of possible monetary profits, better access to services/infrastructure and new opportunities for private enterprises) ofhow shrimp aquaculture and mangrove conservation projects canalter wetland habitats. Intervention discussions lasted aroundforty minutes where afterwards (post-intervention) the samechoice grid was again presented to the same respondents for re-selection with continued discussions on the reasons behind theirchange or lack of change. To conclude a focus group discussion, around up session was conducted with respondents scrutinizing theissues and implications associated with shrimp development orwetland conservation on ecosystem services and their valuesplaced on its access with the frequency of topic mention talliedduring round up discussions. In addition to revealing the learningoutcomes, a comprehension rating was given when focus groupdiscussions terminated to rank the quality of respondent out-comes. This component is based on the respondent’s understand-ing of the choice grid, their selections, and the quality and amountof respondent feedback during both intervention exercise andround up discussions. Ratings ranged from 1 to 3; (1) being ofaverage quality discussion, (2) good quality discussion, and (3)excellent quality discussion.

Buffer zone shrimp farmers were presented one grid and corearea respondents presented three choice grids for each respectiveartisanal fishers, mollusc farmers, and park ranger groups. Fourconstant parameters were presented throughout the study: directprovisioning, indirect provisioning, regulating, and culturalecosystem services. Row one was presented as a directprovisioning good related to the livelihoods of the specificresponding group; row two, as an indirect provisioning service;row three, regulating/habitat ecosystem services that reflectedthe ambient condition of the habitat such as water quality,erosion control and pollination ability that resulted in an endproduct; and row four, a cultural ecosystem service related towetland biodiversity and identity values. Table 2a explains the

Table 2aChoice grid conditions in relation to state/price increments presented to core area respondents.

Artisanal fisherfolk

Natural(10,500,5000 VND annual tax) Current (7,000,000 VND annual tax) Alternative (8,750,000 VND annual tax)

Landings (kg/months) 450Due to little human activity and strictenvironmental regulations the habitat is able todeliver higher fish biomass increasing landings.

300Established after key informant interviews.

150Due to intensive aquaculture activity there is alower biomass, decreasing landings.

Aquatic Biodiversity(no. of species)

6Protected habitat richer in biodiversity withhigher trophic organisms of greater marketvalue (e.g. Pisodonophis boro and Lates calcarifer).

4Aquatic biodiversity is not exceptionallyrich with particularly high market valueorganisms (organisms such as Mugilcephalusand certain gastropods).

2Intensive aquaculture activity has resulted inenvironmental degradation and cannot supporthigher trophic organisms. Only certaingastropods and molluscs of low market value arepresent.

Forest materialdelivery/access(honey, medicines,game/fruits) (min.by boat)

15Time to encounter goods is shorter due to lowdevelopment and conservation efforts.(Conditions are more efficient in maintainingservices such as pollination, primary production,water purification).

30A hypothetical median time between thenatural and alternative state.

45Due to intensive aquaculture activity, regulatingprocesses are impeded and the habitats abilityto maintain and provide goods are degraded,resulting in longer encounter times.

Firefly sighting(monthly duration)

6Sightings are more frequent and lasts,hypothetically, two more months due to theimproved environmental conditions and betterconservation efforts.


2Due to loss of mangroves as a result of intensiveaquaculture, the surrounding environmentcannot support large firefly populations andsightings are reduced.

Mollusc farmers

Natural (10,500,5000 VND annual tax) Current (7,000,000 VND annual tax) Alternative (8,750,000 VND annual tax)

Harvest Frequency(months)

6Harvest frequency is higher due to improvedambient conditions (water quality, suitablenutrient levels) and the crop is hypotheticallylarger in size.

4Established after key informant interviewswhere most farmers harvest four times percrop cycle.

2Harvest frequency is lower due to degradedambient conditions (water quality, suitablenutrient levels) as a result of intensiveaquaculture. Crop is also hypothetically smallerin size.

Aquatic biodiversity(no. of species)

6Protected habitat richer in biodiversity withhigher trophic organisms of greater marketvalue (e.g. Pisodonophis boro and Lates calcarifer).



Forest materialdelivery/access(honey, medicines,game/fruits) (min.by boat)

15Time to encounter goods is shorter due to lowdevelopment and conservation efforts.(Conditions are more efficient in maintainingservices such as pollination, primary production,water purification).

30A hypothetical median time between thenatural and alternative state.

45Due to intensive aquaculture activity, regulatingprocesses are impeded and the habitats abilityto maintain and provide goods are degraded,resulting in longer encounter times.

Firefly sighting(monthly duration)

6Sightings are more frequent and lasts,hypothetically, two more months due to theimproved environmental conditions and betterconservation efforts.



Park rangers

Natural (10,500,5000 VND annual tax) Current (7,000,000 VND annual tax) Alternative (8,750,000 VND annual tax)

Aquaticbiodiversity(no. ofspecies)

6Protected habitat richer in biodiversity with highertrophic organisms of greater market value (e.g.Pisodonophis boro and Lates calcarifer).



Ecotourism(visitortypes)

Local and foreignDue to improved conservation and awareness efforts,the biosphere attracts significant local and foreigntourists. More activities result in higher revenues.

LocalHypothetical scenario where only localnearby tourists (namely Ho Chi Minh City)visit Can Gio mostly over the weekend.

MinimalIntensive aquaculture has impacted the areawhereby almost no tourists visit the Can Giobiosphere for recreational purposes.

Costal Erosion(level ofmanagementurgency)

LowConservation efforts has resulted in increasedmangrove cover and density, subsequently makingcoastal erosion a ‘no issue’ for park authorities.

ModerateErosion is not an issue of priority due toinsignificant impact. Business resumes asusual for park authorities.

HighDue to intensive aquaculture and mangroveconversion erosion and land loss is displacinglocal population and is an issue of importance forpark authorities.

Firefly sighting(monthlyduration)

6Sightings are more frequent and lasts, hypothetically,two more months due to the improved environmentalconditions and better conservation efforts.




Table 2bChoice grid conditions in relation to state/price increments presented to buffer zone respondents.

Shrimp farmers

Natural (25% increase in production costs) Current (No change in production costs) Alternative (50% increase in production costs)

Stocking Density (postlarvae/m2)

60/m2

Farmers stock at lower densities with mostlarvae growing to greater lengths, resulting inpotential higher profits but with theconsequence of lower production output perfarm cycle.

100/m2

Established after key informantinterviews.

140/m2

Farmers stock at higher densities where larvaewill be smaller in size, but due to higherstocking densities, profits may be highergreater due to high production.

Aquatic biodiversity(no. of species)

6Protected habitat richer in biodiversity withhigher trophic organisms of greater marketvalue (e.g. Pisodonophis boro and Latescalcarifer).


2Intensive aquaculture activity has resulted inenvironmental degradation and cannotsupport higher trophic organisms. Onlycertain gastropods and molluscs of low marketvalue are present.

Disease outbreak (stockmortality and productapplication)

20%When an outbreak occurs the surroundingwater quality is appropriate to mitigatepathogen outbreak. Farmers mitigate cropmortality by recovering the infected crop,exchanging water from adjacent canals andnaturally treating the infected stock, loosing20% of the infected crop with minimal productapplication.

50%When an outbreak occurs during a cropcycle, the farmer will lose 50% of theinfected crop after treating it withmedium product applications.

90%When an outbreak occurs the ambient waterquality is poor due to the intensive shrimpaquaculture activity and most of the infectedstock will not survive despite the high use oftreatment products.

Firefly sighting (monthlyduration)

6Sightings are more frequent and lasts,hypothetically, two more months due to theimproved environmental conditions andbetter conservation efforts.

4Established after key informantinterviews.

2Due to loss of mangroves as a result ofintensive aquaculture, the surroundingenvironment cannot support large fireflypopulations and sightings are reduced.


three choice grids and its respective conditions presented to corearea respondents and Table 2b the choice grid presented to bufferzone participants.

2.4. Choice selection analysis

Relationships between respondent choice selection outcomeswere tested with a Fisher’s exact test for each study area dataset. Thechi-squaretest wasnot utilizedascertainproxyselections had valuesbelow five (Upton, 1992). The Fisher’s exact tests determined thestrength of the relationship between the different ecosystem serviceselections under their categorical variable; in this case the priceincrement/state and its degree of significance. In addition todetermining the strength of a choice’s influence on a specificdataset, Pearson’s residuals were calculated. Pearson’s residualsindicate the difference between the observed and fitted values, overthe estimated value of the standard deviation of the observed values.When residuals are greaterthantwo inabsolutevalue, the ecosystemservice selection has had a significant influence on the final p-valueand the overall distribution of the dataset. These relationships arevisually represented by mosaic charts (Hartigan and Kleiner, 1981)along with Pearson’s residual distribution proportions showing thedegree of significance of each ecosystem service selection. Alongwith rectangle sizes, color shades are utilized to represent Pearson’sresidual derivatives and the ecosystem service’ level of significanceon choice distributions. Grey indicates no significance. Whitespecifies cross-classifications that occurred more often than theexpected value, positively influencing distributions; black indicatescross-classification that occurred less than the expected value,negatively influencing data distribution. All the mentioned testswere conducted with the R 2.14.2 statistical package software.

3. Results

3.1. Ecosystem service values

Total ecosystem servicevalues for natural, current and alternativestates at pre- and post-intervention are visually represented as

percentage proportions in radar plots (Fig. 4). Specific core areaselections revealed greater values placed on ecosystem servicesdeliveredatthenaturalaswellasthecurrentstate.Bufferzonegroupsmadesimilar selections with strong initial preferences forecosystemservices delivered at the natural state and the current state.Significantly, price increments at both a 25% and a 50% increasebecame insignificant factors of consideration in both study groupsduring pre-intervention choice selection and even more so, post-intervention. Core area preference distributions displayed strongvaluesforecosystemservicesmaintainedatanaturalstateunderpre-(45%) and post- (56%) intervention deliberations. Preferences forecosystem services maintained under the presented current stateconditionsrevealedveryslightchangesinpre-intervention(36%)andpost-intervention (35%) selection. Few core area selections weremade for ecosystem services maintained under the alternative statewithpre-interventionpreferenceslow(18%)andadecreaseobservedfor post-intervention selections (9%). However, a small proportion(9%) of the alternative state selections still endured post-interven-tion, indicating that particular core area respondents desired someformof aquaculturedevelopment benefitsdespite beingawareof therisk of natural ecosystem service loss/replacement.

Specific buffer zone focus groups selections revealed strongpreferences, pre-intervention (66%) for ecosystem services deliv-ered at the natural state with an increase (74%) in preferences,post-intervention. Values were placed for ecosystems services tobe delivered at the current state (22%), pre-intervention with aslight decrease (21%), post-intervention. Very little value wasexpressed for ecosystem services delivered at the alternative state(12%) pre-intervention, with an observed decrease (6%) for post-intervention selections. Significant values were placed on thebuffer zone specific regulating ecosystem service of water qualitymaintenance where no selections were made under the alternativestate, pre- and post-intervention, despite being aware of thepotential costs and benefits. The indirect provisioning service ofaquatic biodiversity was also highly valued by Can Gio shrimpfarmers (73%) for its delivery under the natural state, pre-intervention. Direct provisioning selections on stocking densityrevealed that Can Gio shrimp farmers preferred stocking densities

Fig. 4. Radar plot of total preference percentage distribution, pre- (full line) and post-intervention (dashed line) for core area and buffer zone groups.


at lower numbers, pre-intervention, where a difference of 12% isexhibited from the alternative or current state to the natural state,post-intervention. In both study groups, cultural service selectionswere more varied between the three presented states indicatingthe anecdotal manner attached to this proxy of firefly sightings.Post-intervention values revealed that 55% of the respondentshrimp farmers preferred cultural ecosystem services at thenatural state and 31% preferred it at the current state. Interestingly,a small proportion of shrimp farmers still declared slightpreferences for ecosystem services at the alternative state, post-intervention, particularly for the direct provisioning service(stocking density) and cultural service (firefly sighting) proxies.

3.2. Mosaic plot

Mosaic plots display choice selection influences on the finalselected outcome distributions (Fig. 5). Core area pre-interven-tion choice selections are statistically different (p < 0.05),whereas post-intervention choice selections were not(p > 0.05). Core area post-intervention selection tests reveal littlechanges in Pearson’s residuals that significantly impacted choicedistributions and although core area post-intervention selectionsshifted more towards the natural state, mosaic distributionsreveal little proportional statistical changes occurring post-intervention. For core area respondents the indirect provisioningservice (aquatic biodiversity) positively influences choice dis-tributions under the natural state (x2 = 2.06) and under thealternative state negatively influences final distributions(x2 = �2.06). Other core area residuals did not have significantconsequences on the final distribution. Interestingly, culturalservice residuals were more equal in distributions throughoutthe three states, where the alternative residual positivelyinfluenced choice distributions, pre-intervention (x2 = 1.88).Based on the pre-intervention residuals, combined with groupdebate outcomes, core area aversion for aquatic biodiversity tobe maintained at the alternative state and respondent highpreferences under a natural state significantly influenced finalcore area ecosystem service values, potentially overridingrespondent desires of gaining potential aquaculture develop-ment benefits. Buffer zone pre- and post-intervention choiceselections were significantly related (p < 0.05) where theregulating ecosystem service (water quality maintenance)significantly influenced final choice distributions positively atthe natural state (x2 = 3.57) and negatively at the current state

(x2 = 3.36) and the alternative state (x2 = �3.77). Residuals for theindirect provisioning ecosystem service (aquatic biodiversity)observed no significant statistical influences as heavy preferencewas initially declared for it at a natural state with little changes,post-intervention. A significant observation is the higherpreference for the indirect provisioning service of aquaticbiodiversity residual under the alternative state becoming anegative value (x2 = �2.15) after the intervention exercise. Thedirect provisioning service presented (stocking density) observedpositive values under the current state (x2 = 2.68) revealing thatCan Gio shrimp farmers are content to farm at current densitiesdespite being presented with the opportunities to changestocking density and culture methods. Cultural ecosystemservice value residuals (x2 = �2.89) under the natural statenegatively influenced final distributions, whereas alternativeresiduals (x2 = 4.70) positively shaped final distributions. Culturalservice distributions observed changes as shifts in valuesoccurred from a current and alternative state to its improveddelivery at the natural state.

3.3. Round up discussion outcomes

Issues debated in the round up discussions were compiled intofrequency percentages to obtain an overview on topical ecosystemservice values discussed in both groups (Fig. 6). All core area groupsdiscussed how unregulated shrimp aquaculture could negativelyimpact wetland habitats with some respondents also cautious ofthe outcomes of excessively conserving natural areas and itsimplications on their livelihoods (70%). The regulating ecosystemservice of storm/erosion mitigation was a constant theme for mostcore area focus groups (70%) with less common issues such as howcurrent natural resources do not provide enough for subsistence(20%) and that management efforts require stronger managerialimplementation (20%) were debated in core area focus groups.Buffer zone focus groups discussed issues related to how shrimpfarming activity can alter ecosystem service delivery and alsorevealed that historical experiences with shrimp farming, inparticular, negative experiences with shrimp disease outbreakshave influenced shrimp farmers to value ecosystem servicesdelivered at the natural state more. Significantly, most shrimpfarmers highlighted that the value of living in Can Gio ischaracterized by the clean and natural area (81%); that rapidand heavy urbanization is something the community would like toavoid. Most shrimp farmers agreed on the negative impacts of

Fig. 6. Discussion frequencies of key topics during round up discussion in core area (n = 10) and buffer zone groups (n = 32).

Fig. 5. Pre- and post-intervention core area and buffer zone mosaic plots of respondent ecosystem service choice selections. The Y variable is indicative of the ecosystemservice conditions in relation to the X variable of state/price increment parameters. Rectangle proportions represent the choices selected. Rectangle heights are fixed. Lengthswere subject to unique respondent choices. A significant observation of the mosaic plot is that buffer zone regulating/habitat ecosystem service values are conditionallydependent on the natural state price increment/conditions with a higher probability of preferences to be selected under the presented natural state.


Fig. 7. (a) Cross cutting themes discussed by both study groups and its degree of importance (1 = highest; 5 = lowest). (b) Total frequency of discussion topic distributionpercentages based on comprehension ratings and type of study group.


intensive shrimp aquaculture but also stressed how it has helped toimprove the local economy (70%). Farmer groups also declared thataquaculture is necessary for an area like Can Gio to develop andimprove community livelihoods through access to modern dayservices and facilities (41%).

Common topics debated by both study groups revealed andcompared what were the most pressing collective issues (1 = high-est order; 5 = lowest order) (Fig. 7a). Core area respondents weremost concerned about the potential negative impacts of intensiveshrimp farming and how it can influence their livelihoods, whereasshrimp farmers did not express as much concern. Interestingly,both groups highlighted the importance of storm/erosion protec-tion and the presence of mangrove forests in delivering thisservice, often referring to a series of heavy storms in 2007,describing how mangrove forests helped mitigate damage in areaswith higher mangrove cover and how other areas, with lessmangrove cover suffered greater damage. Based on

comprehension ratings, the five cross cutting issues werementioned and discussed more often for both study groups whencomprehension ratings had good or average quality (Fig. 7b). Whencomprehension ratings were of good or average quality, discussiontopic frequency decreased and debate quality on ecosystemservices in relation to shrimp aquaculture and wetland conserva-tion were not deliberated in greater detail.

4. Discussion

4.1. Ecosystem service value determinants and its methodologicalconsequences

Natural wetland ecosystem services were highly valued andalthough both groups had different sets of initial values attached towetland protection and shrimp aquaculture outcomes, intrinsicecosystem services were declared irreplaceable. These included


services such as aquatic biodiversity wildlife for communalsubsistence, storm/erosion protection and air/water qualitycontrol. Study results revealed that ecosystem service values stemfrom a user specific context with a final ecosystem service product.These values often undergo personal extrapolation based onseveral factors; for example, buffer zone respondents valued waterquality and aquatic biodiversity higher than core area respondents.Study outcomes further suggest that ecosystem service valuesattached to ecosystem services are pre-determined by (1) thepresence of natural landscapes, (2) the user specific historicalattachments to ecosystem service end products, and (3) currentaccess and interaction modes with ecosystem service functions.The three outcomes that highlight fixed values are: core and bufferzone high initial preferences for the aquatic biodiversity indirectprovisioning service under the natural state; shrimp farmer stronginitial preferences to the water quality regulating ecosystemservice under the natural state, and park ranger selections of eco-tourism and storm/erosion protection services delivered at thenatural state. This predisposition to prefer certain ecosystemservices influence how users value natural habitats and is themajor difficulty in accurate and holistic contingent valuationmethods (Pearce et al., 2006; Schägner et al., 2013). Historicalexperiences also played an important role in ecosystem servicevalue formulation. In the study shrimp farmer respondentsdiscussed the negative impacts of past necrotizing hepato-pancreatitis outbreaks on production and these negative historicalexperiences, combined with the high-risk modis operandi associ-ated with intensive shrimp farming may well have fixed bufferzone regulating ecosystem service values, explaining their explicitpreferences for ecosystem services delivered under the presentednatural state.

Norton et al. (1998) and Costanza (2000) discuss howecosystem service values become fixed and pre-formed at thelocal level on an efficiency value basis. The study results alsosuggest that user interaction modes with ecosystem servicefunctions and eventually ecosystem service end products aredetermined on an efficiency basis. This factor transpired duringgroup deliberations and is also documented in other ecosystemservice valuation studies (Spash and Hanley, 1995; Nunes and vanden Bergh, 2001; Hein et al., 2006; Kenter et al., 2011). Byattempting to incorporate contrasting ecological and economicdrivers with distinct habitat outcomes, the method has conse-quently drawn out the complexities that occur when attachingmonetary values to ecosystem services in a multi functionallandscape (Do and Bennett, 2005; Kenter et al., 2011. Therefore, it isimportant to disaggregate user specific connections to ecosystemservice functions and the end product/goods; where the users willbegin to attach values. This distinction would be an improvementin holistically assessing habitat value for indirect and direct useand non-use services (Barkmann et al., 2008). Further, over-sighting between ecosystem service functions and products can bemade more complex when respondents perceived threats to anintrinsic ecosystem services, i.e., intensive shrimp farmingdegrading water quality. Once threats are triggered it becomesincreasingly difficult to associate ecosystem services to a practicalmonetary value whereby certain regulating and supportingproducts become un-substitutable as it constitutes the usersperception of a pristine habitat (Hall et al., 1992; Carson andMitchell, 1993). This factored with the importance of spatial andhistoric interactions raises further issues on contingent valuationmethods, especially for regulating and supporting ecosystemservices who’s functions tend to be more readily associatedintrinsically to end products such as water/air quality maintenance(Hein et al., 2006; Simões d et al., 2008).

When natural habitats and human social contexts anddeterminants are variable, significant influences on valuation

accuracies may occur (Nelson and Daily, 2010; Schägner et al.,2013; Ellis and Bell, 2013). In monetary valuation studies, naturalvalue is defined as the human worth attached to accessing andutilising natural resources (Hargrove, 1992; Turner, 2000) andessentially, the stronger the values declared for an ecosystemservice, it becomes less realistic to associate the service with amonetary price, especially when the ecosystem service iscommunally deliberated. Costanza (2000), Moons et al. (2008),and Schägner et al. (2013) support this contextual significancewhereby efficiency values, rarity of the presented ecosystemservice, or if certain ecosystem services have been lost or replacedwill determine how users perceive its worth.

Industrialised shrimp farms were not observed in the studylocation as all respondent farms were family owned. However,shrimp farming in southern parts of Vietnam (Ca Mau, Bac Lieu,and Soc Trang), large private companies operate intensive shrimpfarming clusters (World Atlas of Mangroves, 2010). The extent ofindustrialised companies operating may have uniquely mouldedecosystem service values for different communities. Based onfactors such as production efficiency, environmental awareness,social corporate responsibilities and general management coupledwith socio-economic and biophysical components, the involve-ment of industrialised companies would alter community ecosys-tem service values and essentially attitudes on conservation anddevelopment. Ecosystem service provides an approach to holisti-cally manage human landscapes but is limited to large geographicareas and long time scales. It is therefore equally important toselect the most appropriate methods to identify and assess acommunities’ degree of initial connection and relationship with anindustry.

Both respondent group outcomes support individual utilitymaximization (Norton et al., 1998; Costanza, 2000). This initialutility value stems from the personal desire to gain the most out ofa natural habitat that is translatable into a monetary number, withminimal impact to local ecosystem service bundles. Ekins andMax-Neef (1992) and Farber et al. (2002) suggest that someecosystem service values and the human interactions are‘purchasable’ but also declare that certain human needs maynot be satisfied through capital, as individuals simply may notconsider its loss/replacement as worthy beyond a capital value.Capital was a minor influencing factor and despite being constantlyreminded to consider price increments, it seldom affectedrespondent choices and became less significant, post-intervention,in shaping respondent ecosystem service values. This lack ofobserved consideration to price increments in both study groupssupport how intrinsic values will supersede the monetaryconnections to natural ecosystem services where marginal priceincrements seemingly acted to stimulate the respondents toreadily declare a strong willingness to accept payments for stormprotection and water quality ecosystem services (Chee, 2004;McCauley, 2006). However, deliberative approaches go some wayto override inaccuracy issues associated with monetary ecosystemservice valuations and its typology (Turner et al., 2003; Kumar andKumar, 2008) but are more subject to double counting inaccuraciesbased on its lexicographic manner (Fu et al., 2011).

4.2. Deliberation impacts on community ecosystem service values andlearning outcomes

Respondents debated on ecosystem service functions and manyparticipants were able to declare final products such as theprovisioning of shrimp larvae, clean water to culture bivalves, andthe sedimentation process as key indicators (Sasikumar andKrishnakumar, 2011) but were unable to expand on how ecosystemservices help deliver products and how they are potentiallyimpacted by shrimp aquaculture and wetland conservation.


Respondent reception to intensive farming and conservation weretransformed after the intervention exercise, highlighting theimportance of awareness, education and deliberation in influenc-ing ecosystem service values at the local level, particularly ingroups (Wilson and Howarth, 2002). After the interventionexercise, participants better understood how aquaculture andwetland conservation outcomes influence ecosystem servicefunctions with most respondents agreeing that aquaculturedevelopment was essentially a means to install a marketmechanism, potentially leading to short-term infrastructure andemployment improvements. With deliberation influencing finalrespondent choice outcomes, it is important that valuationmethods are conducted through communal deliberativeapproaches of ecosystem service functions for its improvedmainstreaming into wetland management. This will help achievemore equitable and less environmentally detrimental industries byaddressing local values from the ground up (Heal et al., 2001;Armsworth et al., 2007).

Intervention and deliberation outcomes for both study groupsdrew out a stronger sense of altruism that prevailed over economicgains to preserve communal ecosystem services functions, specifi-cally supporting and regulating ecosystem services delivered underthe natural state (Sayer and Campbell 2004; Cowling et al., 2008).Locally expressed as , this connection with natural functionsand human communities eventually became more valuable thanshort-term economic gains when presented with the potential loss/replacement of ecosystem services which development venturesimpact (Sagoff,1998; Wilson and Howarth, 2002; Kumar and Kumar,2008). Farber et al. (2002) emphasized that some ecosystem servicefunctions are so isolated from human economic relation that theybecome irrelevant and only the intrinsic connection remain, holdingonly indirect values in a market economy. Ecosystem services aredelivered in bundles and their indirect values should not beoverlooked as they often resurface when deliberated, sometimeswith unlimited worth, especially when they are perceived to beunder threat or lost at the communal local level.

These vast range of unique learning outcomes discussed by therespondent groups underlines the importance of a participatoryapproach when mapping ecosystem service values (Reed, 2008).However, it also raises further methodological issues for itsapplications in economically valuing multifunctional areas to apractical estimate, especially with the existing linkage gapsbetween ecosystem services, biodiversity and land use (Chanet al., 2006), particularly in rural areas. Asides from Cardinale(2011); the direct roles of biodiversity in ecosystem serviceresilience, societal value and ecosystem service functionality ispoorly understood and integrated. In addition, tipping points andsocial threshold perceptions of when landscapes shift into a lessdesired state as a consequence of human actions and its level ofacceptance by local communities is another research dimensiongap (Schägner et al., 2013). This study attempted to address thisthrough the use of ecosystem services, price increments anddeliberative scenario outcomes but have revealed that theseelements are perplexed when different stakeholders, histories, andspatial scales are encompassed (Diamond and Hausman, 1994;Hanemann, 1994).

Furthermore, the importance of habitat stewardship ininfluencing final choice selection should be quantified. Both usergroups claimed that other more detrimental players such asupstream industries, shipping, and destructive fishing techniquesare the significant stressors impacting Can Gio’s natural habitat.Many buffer zone respondents strongly believed that upstreamindustries, not shrimp farming are the main drivers influencingbiodiversity and ecosystem service capacities to deliver goods/services under a natural state. This stems from discussionoutcomes with shrimp farmers whereby many collect mud crab

(Scylla serrata) and many declared that catch biomass, crab sizes,and catch frequency have decreased over the past five years.Another example stated by park rangers discussed how heavyshipping routes, not aquaculture, is greatly accelerating landerosion in Can Gio. Buffer zone respondents frequently discussedland ownership issues and declared that much of the actual land/farm owners are not Can Gio locals and tend to be more businessorientated, paying less attention to the consequences of theiractions/inactions. These examples highlight the how stewardshipcan also influence and shape the basis of the users connection toecosystem service worth (Farber et al., 2002).

Conclusion

Traditional valuation methods attempt to place monetaryfigures on use values, possibly overlooking non-use values thatmay be of equal or even greater worth to local communities(Hampicke, 1999; Kenter et al., 2011). The study pinpoints themethodological issues associated with ecosystem service deliber-ations and how intrinsic values take shape through groupdiscussion. Both core and buffer zone groups strongly valuedecosystem services delivered at the natural state, where certainstakeholders declared high values for regulating, supporting andprovisioning ecosystem services such as aquatic biodiversity,ambient conditions to mitigate shrimp disease outbreaks, erosion/storm protection and deliverer of clean air/water; cultural valueswere more anecdotal. Focus group discussions revealed that priceincrements are issues of insignificance prior the interventionexercise and even more so, post-intervention; that certain intrinsicecosystem services become extremely difficult to associate with amonetary number influenced by a landscape's unique socio-economic and biophysical historical dimensions which are oftenrobust and pre-formed.

The lexicographic manner of landscape valuation should notrender our attempts to monetarily value habitats. Application ofecosystem services in economic valuation methods will result in amore rounded approach to habitat management in light ofdifferent social and economic drivers and clarify why respondentsmight sacrifice or protect biodiversity ecosystem services. Thefuture need to better incorporate the role of ecosystem servicefunctions and biodiversity in valuation methods is required toaddress the uncertainties in landscape valuation with communaldeliberation and discussion an integral part of the process.

Acknowledgments

The authors would like to thank the Royal Thai Government andthe Swedish International Development Cooperation Agency(Sida) for funding the study and fieldwork. Gratitude is alsoexpressed to the Can Gio Park Management Authorities and theCan Gio’s People’s Committee for logistic and personnel assistance.

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