This mini-dissertation contains the results of research to establish a[1 economic value for the mangroves of the Mngazana Estuary in the Eastern Cape. The research is presented in two parts. Component A comprises the literature review and also describes the scope and context for the study, its purpose and the proposed methodology. Component B presents the results of the research in the format of an article to be submitted for publication to the African Journal of Marine Science. Estuaries and mangroves are among the most threatened habitats in South Africa, with the third largest mangrove forest in South Africa at the Mngazana Estuary on the Wild Coast of the Eastern Cape gradually reducing in size. A lack of appreciation of their value has resulted in policies and decisions that promoted the conversion of estuary and mangrove ecosystems to alternative uses, and caused a large-scale loss of mangroves throughout the world. Apart from their key ecological role, the Mngazana Estuary mangroves provide important benefits to the 645 households in three villages that utilise the resources and the sustainable use and management of the mangroves is essential. Economic valuation ascribes values to traded and untraded environmental resources and is a tool that supports policy formulation and decision-making on sustainable management of resources like mangroves. The theory of total economic value provides the conceptual framework for estimating the economic value, but constraints limited this study to estimating the socio-economically significant benefits the mangroves bestow on the communities around the Mngazana Estuary. Using information collected in a household survey and focus group discussions, market-price methods were used to estimate the value of mangroves harvested for building materials and the subsistence consumption of fish by the communities. Values were estimated for mangrove-dependent canoe trails and honey production operations, while a recreational use value was estimated on the basis of travel costs and expenses incurred by visitors to the holiday cottages adjacent to the estuary. The results were incorporated in 20-year valuation models with the net annual benefits then discounted to present value terms. Sensitivity analysis was performed to estimate lower-bound, upper-bound and most-likely values for the benefits. The minimum economic value of the mangroves was estimated to be between R1.1 and R13.6 million, with a most-likely value at a real 5% discount rate of R7.4 million. This study has shown that policies for managing environmental resources must be ecologically, socially and economically sound. This requires an integrated approach to address the socio-economic needs of local communities while safe-guarding environmental resources. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

The zooplankton community of the main channel of the Mngazana estuary was investigated on six occasions over one year. Spatial and temporal variability in zooplankton abundance and distribution were sampled using two slightly modified WP2 plankton nets of 200 μm mesh and 57 cm mouth diameter. Nets were fitted with calibrated Kahlsico 005 WA 130 flow meters. A set of environmental variables were also measured at each site. The water column of the main channel of Mngazana estuary was stratified in summer but well mixed in winter. Temperature progressively increased from the lower stations to the upper reaches of the estuary. Maximum vertical temperature differences occurred in the middle estuarine reaches. Salinity progressively decreased from the lower reaches to the upper reaches, but was generally above 26 from Station 3 to Station 8. Only during November 2005, were salinity readings low due to heavy rains. Summer salinity values were always lower than the winter salinity values as a result of summer rainfall. A total of 76 zooplankton taxa were identified. The estuarine copepods Acartia natalensis and Pseudodiaptomus hessei dominated the assemblage, with maximum abundances in the middle to upper reaches. Acartia natalensis reached high densities in winter (> 50 000 m-3) although lowest abundances were recorded when maximum rainfall was received (November 2005). Wooldridge (1977) and Deyzel (2004) recorded maximum densities during summer. Pseudodiaptomus hessei reached high densities (> 17 000 m-3) during the highest rainfall month. Previous studies indicated that this pioneer species is able to recover quickly after a flood and subsequently increase rapidly in numbers. The mysid, Mesopodopsis africana reached high densities (> 5 000 m-3) in the middle estuarine reaches during summer. Ichtyofauna, brachyura and anomura were important contributors to the merozooplankton component of the community. The maximum number of species was recorded during winter in the lower estuarine reaches, when vertical differences in salinities were minimal.

Many South African estuaries are currently believed to be generating lower levels of services than they used to in the past due to substantially reduced inflow of river water, among other reasons. The basis by which river water is allocated in South Africa has had to be re-examined. Local authorities are now required to integrate into their development planning sensitivity to the ways estuaries work; the relevant legislation being the Municipal Systems Act No. 32 of 2000. Sound water resource management requires that the benefits and costs of different water allocations be compared and an optimum determined. The Contingent Valuation Method (CVM) is used in this study to estimate the benefits of changing allocations of river water into estuaries. This study builds on a CVM pilot project done at the Keurbooms Estuary in the Southern Cape in year 2000 (Du Preez, 2002). Further CVM studies were conducted at the Knysna, Groot Brak and Klein Brak estuaries (Dimopolous, 2004). The CVM is a valuation technique based on answers given to carefully formulated questions on what people are willing to pay for specified changes of freshwater inflows into estuaries. The CVM depends on there being a close correspondence between expressed answers given to hypothetical questions and voluntary exchanges in competitive markets that would be entered into if money did actually change hands. The fact that it has proved very difficult to establish this correspondence has led to CVM being subject to criticism. However, many aspects of this criticism have been addressed in the form of methods to reduce biases, and the application of the technique has grown steadily in popularity during the past 25 years. Four estuaries, the Swartkops, Kariega, Mngazi and Mngazana, were surveyed as part of this study in order to determine users’ willingness to pay (WTP) for changes in freshwater inflows. Considerable research time was devoted at the estuaries getting to know how things worked around and in the estuaries. The Swartkops estuary is a permanently open system within the Nelson Mandela Bay metropolitan area. The estuary has the third largest salt marsh in South Africa. Its banks are highly developed with residential and industrial property and it is heavily used for both recreation and subsistence fishing by locals. The Kariega estuary is located near the semi-rural town of Kenton-on-sea, between Port Elizabeth and East London. Although it is permanently open, the Kariega estuary has very low inflows of river water. It is mainly used by retired pensioners living in holiday houses at Kenton-on-sea. The Kariega is not heavily used for recreation and subsistence fishing, except during holidays and the festive season because of its proximity to other estuaries such as the Bushmans and the Kleinemond. The Mngazi and the Mngazana estuaries are located in the Wild Coast area of the Eastern Cape, in the Port St Johns Municipal district. The Mngazi is a temporarily open/closed system which does not have high botanical ratings, although it is heavily used by visitors to the well known Mngazi River Bungalows, a highly rated hotel near the mouth of the Mngazi River. The Mngazana estuary is a permanently open system renowned for its Mangrove forests and excellent fishing spots. Both the Mngazi and Mngazana estuaries are located in rural areas and are heavily used by local village residents for subsistence purposes.