Economic Valuation of a Mangrove Ecosystem Threatened by Shrimp Aquaculture in Sri Lanka
ABSTRACT Mangrove ecosystems in Sri Lanka are increasingly under threat from development projects, especially aquaculture. An economic assessment is presented for a relatively large (42 ha) shrimp culture development proposed for the Rekawa Lagoon system in the south of Sri Lanka, which involved an extended cost-benefit analysis of the proposal and an estimate of the "total economic value" (TEV) of a mangrove ecosystem. The analysis revealed that the internal benefits of developing the shrimp farm are higher than the internal costs in the ratio of 1.5:1. However, when the wider environmental impacts are more comprehensively evaluated, the external benefits are much lower than the external costs in a ratio that ranges between 1:6 and 1:11. In areas like Rekawa, where agriculture and fisheries are widely practiced at subsistence levels, shrimp aquaculture developments have disproportionately large impacts on traditional livelihoods and social welfare. Thus, although the analysis retains considerable uncertainties, more explicit costing of the environmental services provided by mangrove ecosystems demonstrates that low intensity, but sustainable, harvesting has far greater long-term value to local stakeholders and the wider community than large shrimp aquaculture developments.
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- "c o m / l o c a t e / e c o l i n d negative environmental outcomes (Rosenberry, 1998; Páez-Osuna, 2001; EJF, 2003). However, the economic benefits of shrimp aquaculture should not be disregarded as added capital can boost the national economy, improve local livelihoods, and aid in rural development (Frankic and Hershner, 2003; Gunawardena and Rowan, 2005). Vietnam's aquaculture is poised to intensify as declared by Government Decision No. 21, 1998 and Government Decision No. 67, 1999 (EJF, 2003), encouraging aquaculture expansion at the private level, exposing mangrove wetlands to future pressures. "
ABSTRACT: Wetland valuation methods often apply monetary driven approaches that may undermine intrinsic ecosystem values. Utilizing a stated preference method, the study identified and mapped local stakeholder ecosystem service values between subsistence wetland and shrimp farmer groups in Can Gio, Vietnam. Through focus group choice experiments, ecosystem services correlating to unique price increments and cost/benefit tradeoffs between hypothetical intensive aquaculture developments and mangrove conservation scenarios were investigated. Selection outcomes exhibited strong values for ecosystem 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 selected the hypothetical intensive aquaculture development scenario (core area pre-intervention 18%, post-intervention 9%; buffer zone pre-intervention 12%, post-intervention 5%), and instead, most respondents avoided the costs and benefits of intensive aquaculture development in preference for maintaining natural ecosystem services. Group deliberations drew out a higher sense of altruism and responsiveness to intrinsic wetland values that superseded the potential economic gains of aquaculture developments, whereby certain ecosystem services were deemed economically unassociable and irreplaceable for both study groups. The qualitative results expose the difficulties in monetarily measuring ecosystem services, highlighting the need to incorporate approaches that integrate the intrinsic values attached to ecosystem services.Ecological Indicators 07/2014; 46. DOI:10.1016/j.ecolind.2014.06.012 · 3.23 Impact Factor
Maritime Studies 01/2014; 13(1):13. DOI:10.1186/s40152-014-0013-6
- "As a result, farming area expanded over the northwestern part of the country. Small-scale farmers conducted their operations within their community areas, while large and medium-scale farmers shifted from place to place by converting mangrove forests (Gunawardena and Rowan 2005) and coconut plantations into shrimp farms (Cattermoul and Devendra 2002). However, the expansion of aquaculture into the eastern part of the country was restricted due to the civil war that was taking place. "
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- "This study utilizes a novel approach, the replacement cost method, for estimating the ecosystem service of nutrient regulation provided by oysters. Previous studies most commonly associated with waste or nutrient regulation and storm protection are linked to the services provided by wetlands –. "
ABSTRACT: Suspension-feeding activities of oysters impart a potentially significant benefit to estuarine ecosystems via reduction of water column nutrients, plankton and seston biomass, and primary productivity which can have a significant impact on human well-being. This study considered nitrogen regulation by eastern oysters Crassostrea virginica in the Mission-Aransas Estuary, Texas, USA, as a function of denitrification, burial, and physical transport from the system via harvest. Oyster reefs were estimated to remove 502.5 kg N km(-2) through denitrification of biodeposits and 251.3 kg N km(-2) in burial of biodeposits to sediments. Nitrogen is also physically transported out of the estuary via harvest of oysters. Commercial harvest of oysters in the Mission-Aransas Estuary can remove approximately 21,665 kg N per year via physical transport from the system. We developed a transferable method to value the service of nitrogen regulation by oysters, where the potential cost equivalent value of nitrogen regulation is quantified via cost estimates for a constructed biological nutrient removal (BNR) supplement to a wastewater treatment plant. The potential annual engineered cost equivalent of the service of nitrogen regulation and removal provided by reefs in the Mission-Aransas Estuary is $293,993 yr(-1). Monetizing ecosystem services can help increase awareness at the stakeholder level of the importance of oysters beyond commercial fishery values alone.PLoS ONE 06/2013; 8(6):e65314. DOI:10.1371/journal.pone.0065314 · 3.23 Impact Factor