Date of Award


Degree Type


Degree Name

Doctor of Philosophy in Environmental Sciences


Natural Resources Science


Natural Resources Science

First Advisor

Arthur J. Gold


The dialogue pertaining to the management of riverine and coastal ecosystems has evolved over the past decade to consider ecosystem goods and services due to their ability to link ecosystem structure and function to human well-being. Ecosystem services are “a wide range of conditions and processes through which natural ecosystems, and the species that are part of them, help sustain and fulfill human life” (Daily et al. 1997 p.2). Ecosystem goods emerge from ecosystem services and are defined as “organisms and their parts and products that grow in the wild and … are used directly for human benefits” (Daily et al. 1997 p.4). Protected areas, such as national parks, and environmental flow regimes that identify critical aspects of river flow, are increasingly being utilized as management measures to enhance resiliency, protect biodiversity, and preserve the delivery of ecosystem goods and services.

Recently it been proposed that aquatic ecosystem goods and services can serve as a common currency to account for the benefits and losses associated with altered flow regimes and define the risks in a transparent manner since they provide immense value to all stakeholders (Arthington 2012). Adopting this idea, my dissertation research comprises three studies focused on the ecosystem goods and services related to the protected portion of the Wami River and Estuary encompassed within Saadani National Park (SANAPA), Tanzania. The first study investigates the use and perception by different groups of downstream stakeholders of the value of ecosystem goods and services. The second study examines the effect of SANAPA on the tradeoff between two specific ecosystem services and whether the local surrounding communities fell into a poverty trap as a result of the restrictive measures put in place when the park was created. The third study assesses how proposed water withdrawals for a large scale irrigation project located just upstream of the park’s boundary would alter the freshwater inflow regime and potentially impact the delivery of ecosystem goods and services to SANAPA and the neighboring local communities.

The need for enhanced understanding of how different stakeholders perceive and depend upon an array of ecosystem goods and services is a critical research priority. In our first study, we employ a mixed methods approach comprised of focus groups and face-to face surveys to examine the specific ecosystem goods utilized by residents and compare and contrast the perceived value of 30 ecosystem services held by upstream residents, downstream residents, tourism officials, and conservation organizations. Our key finding is that a good deal of consensus exists among these groups in regards to which ecosystem services are deemed most and least valuable. Each group places a high value on the provision of domestic water, habitat for wild plants and animals, tourism, and erosion control, and a relatively low value on the prevention of saltwater intrusion, refuge from predators, spiritual fulfillment, non-recreational hunting, and the provision of traditional medications and inorganic materials for construction. Differences emerge, however, between the groups in the value assigned to the conservation of riverine and estuarine fauna, intrinsic value, and the provision of raw materials for building and handicrafts. The fact that residents assigned a higher priority to raw materials and a lower priority to the intrinsic value and conservation of riverine and estuarine fauna than the tourism and conservation officials suggests that they are very reliant upon the resources of the Wami River and Estuary for their sustenance and income.

The findings from our first study fall in line with the larger pattern observed around the world, namely, that many coastal communities in developing countries, especially the rural poor, rely heavily upon natural resources for their subsistence and livelihoods. Their access to these resources, however, often changes when protected areas are established. The short- and long-term gains and losses to local residents associated with protected areas remain largely unexplored, especially empirically. In our second study, we integrate remote sensing data of mangrove cover with georeferenced household survey data in an econometric framework to assess the environmental and economic impacts of enhanced mangrove protection efforts undertaken to preserve biodiversity in SAN APA on the neighboring local communities. Specifically, we examine the effect of strengthened enforcement of the prohibition of mangrove harvesting on the tradeoff between two specific ecosystem services (i.e., the short-term benefits from cutting mangroves and the long-term benefits from harvesting the fish and shrimp that thrive if mangroves are not cut), and whether households fell into a poverty trap as a result. Our findings suggest that many households experienced an immediate loss in the consumption of mangrove firewood with the loss most prevalent in richer households. However, all wealth classes appear to benefit from long-term sustainability gains in shrimping and fishing which result from mangrove protection. Overall, the households that have stopped using mangroves for firewood can be considered the “losers” from establishment of SANAPA, while those who started fishing/shrimping (or making more revenue out of it) are the “winners.” Our data suggest that there are more “winners” than “losers” with the proportion of households that newly engaged in mangrove-related income activities after SANAPA outweighing the proportion of households that no longer use mangroves for their firewood. The creation of SANAPA shifted the future trajectory of the area from one in which mangroves were experiencing uncontrolled cutting to one in which mangrove conservation is providing gains in income for the local villages due to the preservation of nursery habitat and biodiversity.

While the results of our second study are encouraging, the health of the mangroves, existence of the mangrove reliant fish and shrimp species, and continued delivery of the other ecosystem goods and services valued by the stakeholders in our first study, are dependent upon sustained freshwater flows into the lower reaches of the Wami River and Estuary. Upstream anthropogenic activities can alter the magnitude, frequency, duration, timing and quality of freshwater inflows. These alterations to the natural flow regime can cause abiotic and biotic changes within the downstream riverine, estuarine, and coastal ecosystems affecting the availability of the ecosystem goods and services, and in turn, the overall well-being of the stakeholders reliant upon them. In our third study, we examine the potential effects of water withdrawal (i.e., abstraction) from a proposed 10,500 hectare irrigated biofuel project on the Wami River on the delivery of ecosystem goods and services to SANAPA and the neighboring local communities. We utilize daily flow data collected from 1954 to 1978 to derive a number of low flow and extreme low flow parameters for flow durations ranging from 1 to 90 days to characterize the historic and post-irrigation freshwater flow regime of the Wami River. Our findings demonstrate that the proposed withdrawals during the dry season would dramatically alter the flow regime of the lower Wami River and create conditions unlike any observed over the 24 year period of flow records analyzed. Under the abstraction scenario, there is a 10-fold increase in the occurrence of low flow values observed historically. Moreover, the incidences of zero flow days over the 24 year period of record rise from 15 to 300, creating extended periods of no-flow conditions that would completely dry out lower portions of the Wami River. These changes would have profound effects on the habitats, wildlife, fisheries, and human values and functions that constitute Saadani National Park. Therefore, it is essential that large scale water withdrawals must be approached with caution in perennial, free-flowing rivers draining arid watersheds of eastern Africa to sustain the critical riverine and estuarine linked ecosystem goods and services of downstream protected areas.



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