6 INDIRECT USE VALUES

6.1 Support to off-site fisheries

Description: Mangroves support commercial and subsistence fisheries through acting as nursery areas for juvenile stages and as feeding areas for adults. In a study of juvenile fish species within mangroves in Nabq, Ahmed Al (1992) identified twelve fish species and measured their abundance (see Table 9). However, the results must be viewed with caution due to the difficulty in collecting accurate data. Fish are easily scared and can avoid capture; hence, the data is likely to be an underestimate. During the field visits for this study, numerous shoals of juvenile fish were noted and thousands of small shrimp or prawns were seen in the mangrove creek at Ras Mohammed. In addition, the mangroves play an important role in supporting the productivity of nearby corals and seagrass beds that are also important commercial and subsistence fishing areas and fishery support systems. This is achieved through the production and transfer of significant amounts of organic material, particularly from seeds and the exfoliation of leaves.

Table 9 Relative abundance of fish (number caught per 300m trawl) at Wadi-Kid and Nabq between June 1989 and May 1990

Values elsewhere: There has been considerable work and debate on the link between mangroves and fishery catches. In the most recent comprehensive review, Ronnback (2001) highlights various studies where between 30% and 80% of fish catches and up to 100% of shrimp catches have been attributed in some way to mangroves. In developing countries, the annual market of fisheries supported by mangroves ranges from US$ 900 to US$ 12,400/ha/yr, with US$ 3,400/ha/yr as a mean (Ronnback, 2001). However, subsistence catches are usually omitted from these calculations.

Valuation techniques: A value can be estimated for this function based on market prices and “change in productivity” (i.e. what the change in production would be without the mangroves). Effectively, a proportion of the associated value (fish market value less costs) can be attributed to the mangroves based on assumptions as to the dependency links.

Current values: It is extremely difficult to determine with any degree of accuracy the precise relationship between mangroves and fisheries due to the many dynamic influences at play. However, the approximate value of fish landings for fish caught in the Red Sea that are associated with mangroves is around US$ 130 million, as highlighted in Table 10 below. Assuming the dependence of these fish catches on Egypt’s mangroves is between 5 - 25%, and based on there being 500 ha of mangroves, the approximate fisheries value would be in the order of US$ 13,000 to US$ 64,000 per year per hectare. However, this may be on the high side if the fish catches are more dependant on mangroves elsewhere in the Red Sea. Given the available data on juvenile fish within the mangroves, and the number seen during the site visits, these values may be on the high side. Indeed, some of Egypt’s mangroves are not actually inundated by water. An assumed value of US$ 13,000 per ha per year is therefore recommended.

Note also that costs of catching the fish (e.g. boast, fuel equipment and labour – at opportunity cost) should be deducted from the revenues to arrive at a net welfare or benefit value. These could be in the order of 10 – 40%. There will also be a component of subsistence fisheries and non-recorded fish catch to consider, which would increase the overall value.

Table 10 Egyptian fish catch dependant on mangroves

Note: Based on Galal (pers com) and fish catch data provided by FAO (2002).

Potential values: The overall value may increase if the area of mangroves increases, for example through mangrove restoration. The precise relationship between mangrove area and commercial fish catches is uncertain, although various means of calculating this have been proposed. For example, Ruitenbeek (1992) includes both an impact intensity parameter and an impact time-lag parameter.

Socio-economic aspects: A large number of fishermen depend on fisheries as a living in Egypt. In 1998, the number of fishermen employed in fisheries in the Egyptian Red Sea coast was 17,918, excluding fishermen from Safaga, Berenice, Shalateen, Halaib and the Sinai Peninsular (Kemel, 1998). In addition to the many commercial fishermen dependent on Red Sea fisheries, many coastal communities, including Bedouin are dependent on them. Local fishing Bedouin for example not only depend on fish as an important part of their diet but they also trade their surplus catch to generate money to pay for many other basic requirements. The mangroves may therefore play a vital role in the supporting these communities.

Recommendation:

• It would be useful to have a comprehensive study undertaken on the links between mangroves and both commercial and subsistence fisheries in Egypt.

6.2 Biological support of off-site habitats and species

Description: The mangroves of Egypt help to support an internationally important population of wild birds. There are over 470 species, over two thirds of which are migrant birds (Baha El Din, 1999), a large number of which depend upon the rich mud, sand and reef flats and mangroves of the Red Sea and Gulf of Aqaba. Many of the birds identified in the Global Environment Facility coastal bird survey were recorded in mangrove areas (GEF, 1997). In addition, the mangroves help support other nearby habitats (e.g. sea grasses, corals, sabkahs, salt marsh) and species (e.g. turtles, dugong) indirectly through seagrass support. This interaction can be through a range of mechanisms such as nutrient influxes and species migration. Saenger (2002) estimates the annual litter fall of mangroves in Egypt to be around 1,350 tonnes per year, assuming around 2.8 tonnes/ha/yr.

Abu-Aisha (1994) undertook surveys of seagrass beds near mangroves and found significant stands of Thalassodendron ciliatum, Halophila stipulacea, Halophila ovalis and Halodule uninervis on adjacent reef flats in Ras Mohammed, and Halophila ovalis and Halodule uninervis in the mangrove creek at Ras Mohammed creek. The specific role of fisheries support was addressed in Section 6.1 above.

Values elsewhere: There are few if any studies that specifically address these values. However, elements of such support values may have been incorporated in the mangrove non-use value questionnaire survey mentioned in 7.1 (Bann, 1999).

Valuation techniques: A major part of the economic value of this support can be determined through stated preference questionnaire surveys that estimate recreational and non-use willingness to pay values of visitors and nationals. However, the questionnaires would need to be designed appropriately to highlight the links to ensure that the values were incorporated in the overall valuation. In addition, there may be a value associated with some links that accrue in other countries, for example the value of birds when they have migrated elsewhere. That is far more difficult to determine.

Current values: The current value of this support has not been determined. However, part of the value is captured by the estimates for mangrove recreation and non-use values.

Potential values: It would be possible to enhance the value of biological support to birds through educational programmes highlighting the links between mangroves and the birds. It can also be achieved through organizing more tourism and recreational activities based on the bird migrations. For example, this could include special bird tours, bird watching events and bird watching facilities provided at appropriate times of the year. Information on the links could be provided in a tour guide information pack.

Socio-economic aspects: Through enhanced recreation opportunities, more jobs may be created. Interested local villagers and Bedouin could be trained to become tour guides knowledgeable on birds and bird watching.

Recommendations:

• Undertake studies into the links between mangroves and other habitats and species. In particular, focus on the links between mangroves and birds.

• Consider creating more bird watching facilities, (e.g. bird hides near important feeding and nesting areas).

• Produce an information pack for tour guides.

6.3 Shoreline protection function

Description: Some mangroves along the coast of Egypt provide a shoreline protection function by reducing coastal erosion. The existence and significance of this function is highly site specific. In most locations, the mangroves act as a second line of defence after the fringing reefs (e.g. in Nabq and S. Safaga). In Nabq, several of the mangroves provide an important role in this respect. Without the mangroves, the soft sediments of the alluvial coastal plain and the important terrestrial Reserve habitats could become severely eroded (Photo 8). In other locations, such as Ras Mohammed and Abu Monkar Island, where the mangroves are surrounded by land, the mangroves do not provide any such a function.

Values elsewhere: Ruitenbeek (1992) estimated the value of mangrove coast erosion protection at US$ 240/ha for the 304,000 ha of mangroves in Bintuni Bay, Indonesia. This was based on damage costs avoided of potential agricultural production. Christensen (1982) came up with a coast protection value of $165/ha/year. More recently, Sathirathai and Barbier, (2001) estimated the value of coastline protection and stabilization for the mangroves around Tha Po village in Thailand, to be US$ 35,000/ha. This is equivalent to US$ 3,680/ha/year over 20 years at 10% discount rate. The valuation was based on the costs of providing an offshore breakwater to provide the same function (US$ 875/meter of coast), and an assumption that 1/3 of the mangroves along the coast provided this function.

Valuation techniques: The preferred method for valuation is generally the lower of damage costs avoided and the replacement cost approach. In Egypt, the situation is complicated by the fact that land values are artificially low. The Government has officially set the value of coastal land at US$ 1/m². Although land is currently occasionally traded at higher prices, this information is extremely difficult to come by. The coast erosion function in Egypt is thus best determined using the replacement cost approach, based on the cost of replacing the erosion function of the mangroves, should the mangroves disappear. However, the value will be highly site specific. At many locations the mangroves may have no erosion protection function because there is little wave action (e.g. in protected bays) and because of the hard nature of the shoreline. In other locations, there may be erosion, but the consequence of losing some coastal land is insignificant, particularly in the south where there is little development. On the other hand, in ecologically important sites (e.g. national parks) and in developed coastal areas, the value of land may be significant.

Current values: The costs for providing a suitable simple protection structure at Nabq may be in the order of

US$ 75/m. This is based on the cost of coast protection elsewhere along the Sharm El Sheik coast (Galal, pers com, 2002), but somewhat reduced given the relatively low wave energy at the site. Given that the length of mangroves along the Nabq coast is around 7,000m, and that there are 52.5ha of mangroves in Nabq, this gives a one-off value (assuming no maintenance cost) of around US$ 10,000/ha. This equivalent to US$ 1,000/ha/yr (in perpetuity) based on 10% discount rate. Few of the other mangrove sites visited appeared to have much of an erosion role.

Potential values: There is scope for enhancing this function in several locations, but particularly in Nabq. Indeed, some mangrove restoration work is already underway to slow the erosion of the main coastal track from the Nabq Reserve entrance to the cafeteria.

Socio-economic aspects: The Bedouin village at Hamata may be partly protected from erosion and flooding by the mangroves.

Recommendation:

• Problems of erosion elsewhere along the coast could be investigated, and the potential role of mangroves could be considered.

6.4 Sediment regulation and accretion

Description: In many locations, the mangroves act as an important regulator of sediment movement. Firstly, the mangrove trees and roots (pneumatophores) help trap terrestrial sand being blown along the shore, thereby reducing the volume of sand from being blown onto the fringing reefs. Secondly, during flash floods, the mangroves slow the movement of flood waters full of sediment, causing much of the sediment load to settle on the landward side. This helps protects adjacent and nearby coral reefs from being smothered and killed by excessive sedimentation. These two functions also result in accretion of land in the coastal plain, extending the land slowly out to sea. A study on flash floods in Egypt suggests that their frequency and the potential damage they can inflict is significant and increasing (Hefney, 1997).

At Marsa Shakraa, where considerable deterioration and damage to mangroves has occurred in recent years, the loss of this sediment control function may have significantly contributed to damage of coral reefs adjacent to the Ecolodge Shagra Village resort. After a flash flood a few years ago, the corals in the area were seriously damaged through flood sedimentation. They have still not yet fully recovered, resulting in snorkellers and divers having to go further afield to appreciate good corals.

Values elsewhere: There do not appear to be any values for these functions relating to mangroves in the literature. However, Hodgson and Dixon (1988) clearly demonstrate the potential economic impact from loss of coral cover, coral species and fish catch associated with sedimentation affecting coral reefs from logging in Palauan, Philippines. They estimated that potential revenues of US$ 8.6 from logging would be outweighed by loss of fishery and tourism revenues of US$ 6.2 million and 13.9 million respectively.

Valuation techniques: As with coast protection, the value of this sediment regulation function can be determined by either the damage costs avoided or the replacement cost technique. The former would be the preferred method, but requires considerable information on various complex events and linkages. For example, information is needed on the potential sedimentation impact to corals, their associated economic values and recovery times, at each site for a range of various storm return periods.

Current values: At sites where there is an obvious sediment control function protecting valuable nearshore coral reefs, the replacement cost approach is used. This is the case for example for the mangroves at Nabq, and for many fringing mangroves along the Red Sea protectorate coast at the mouth of Wadis. An estimate of the value is given by the cost of providing a structure that will provide the equivalent role of slowing storm flood waters and causing sediments to settle. The cost of providing such a function could again be in the order of US$ 75/m of coast. Again, given that at Nabq, there is 7,000 m of mangrove fringed coastline, it could be worth US$ 525,000, or split over the 52.5ha, US$ 10,000/ha. This equates to an annual value of around US$ 1,000/ha/yr based on a 10% discount rate.

Potential values: There may be scope for enhancing this function in locations where there used to be healthy mangroves in large wadis, for example at Marsa Shakraa.

Socio-economic aspects: Protection of coral reefs by this function will indirectly help to support many local livelihoods that depend on the reefs.

Recommendation:

• The situation at Marsa Shakraa should be investigated. This would require assessment of the coastal road and its impact on hydrological conditions at the site. The mangrove population could then potentially be restored to its former healthy state.

6.5 Other mangrove functions

There are various other mangrove functions for which there is little data available and where the relationships are complex. This includes for example a water quality control and waste assimilation function, storm protection, nutrient control, groundwater control, microclimatic stabilization and carbon storage. For example, freshwater lenses are often found at the landward side of mangroves (which explains how they can survive in what appears to be deserts) which are used by wildlife who come to drink. Although all are important roles, they do not provide significant measurable economic values compared to the other values discussed above. Due to this, and the small scale of mangrove areas in Egypt, with the exception of carbon storage (see below), they are not assessed further.

A value for carbon storage for Egypt’s mangroves could be calculated based on the annual overall growth of mangroves and estimated annual litter fall. The latter is estimated to be 2.8 tonnes litter/ha/yr (Saenger, 2002). However, the science behind leaf litter decomposition and breakdown to become methane should perhaps be considered further. De Lopez et al (2001) suggest that a carbon storage value for mangroves in Cambodia could be in the order of US$ 2/ha/year.