Factors influencing awareness of community-based shorebird conservation projects in Australia

We examine the awareness of potential volunteers (n = 360) living near nine community-based shorebird conservation projects. About half of the people sampled (54%) were unaware of the nearest project. Awareness of interviewees varied substantially among projects (28-78%). Apart from gaining awareness of projects through membership of natural history groups (43%), many respondents heard of projects through friends and relatives (20%), rather than through media such as newspapers (14%) and television (2.3%). We demonstrate that community-based projects can be quantitatively and critically assessed for awareness. The use of rapid, cost-effective assessments of awareness levels has application in many conservation projects. <br /

Participatory appraisal for potential community-based mangrove management in East Africa

Mangroves are among the most threatened ecosystems in the world and the coastal forests of East Africa are no exception to this trend. Although conservation, rehabilitation and sustainable management plans have been developed in various tropical regions, only a few locally based approaches have been launched along the Indian Ocean coast of Africa. In order to identify possible conditions for sustainable management of mangroves based on socio-economic and ecological considerations, we present a participatory approach designed to evaluate the relationships between mangroves and human activities and the use of multi-criterion analysis to identify management solutions. To achieve this goal, all the subjects involved in mangrove management (local communities, institutions and researchers) took an active part in the process. The research was carried out in three communities relying on mangrove swamps: Kisakasaka village on the island of Zanzibar, Mida Creek in Kenya, both relying on mangrove forests known to be endangered by over-exploitation, and Inhaca Island in Mozambique, where mangroves are more pristine. Families were the hub of the research and the importance of each of their economic activities was assessed. We then examined the methods by which mangroves are exploited by the local community and by other stakeholders working in the study areas. Our results show that the mangroves in Inhaca are exploited only for household needs and the pressure on the forests is still ecologically sustainable. In contrast, there is a well-established demand for mangrove products in Kisakasaka and Mida Creek and the mangroves represent an essential source of income for the families, resulting in an ecologically unsustainable rate of exploitation. Therefore, possible alternatives to the current management practices were identified in the two areas by means of a participatory approach. Multi-criterion analysis was then used to compare and discuss the alternatives in terms of social, economic and ecological criteria.Link_to_subscribed_fulltex

Quantifying the density of mangrove crabs: Ocypodidae and Grapsidae

Numerous studies have highlighted the importance of crabs within mangrove ecosystems, but tested methods of enumeration are virtually non-existent. The aim of the present study was to assess the accuracy of quick, non-invasive methods for estimating the population density of three species of mangrove crabs in East Africa: Uca annulipes, Sesarma guttatum and Neosarmatium meinerti. Methods employed depended on the behaviour and habitat of each species. Counts of U. annulipes and N. meinerti individuals that were active on the surface (visual counts) and burrow counts (of U. annulipes) were compared to actual densities. Actual densities were determined by excavation of U. annulipes, and by multiplying counts of N. meinerti burrows by the mean number of crabs per burrow. Visual counts of marked individuals of S. guttatum were compared to known densities of marked crabs. For N. meinerti two visual counting methods were tested: (1) instant counts - crabs were counted every 5 min during 0.5 h and the highest count taken; and (2) continuous counts - all burrows were tagged, and those from which a crab emerged during 0.5 h were totalled. For U. annulipes on Inhaca Island (Mozambique) visual counts underestimated excavated numbers by 27%, whereas burrow counts overestimated numbers by 46%. These values were similar for both sexes, and on both spring and neap tides. Burrow counts and visual counts estimated absolute numbers of U. annulipes with equal consistency. At Mida Creek (Kenya) visual counts underestimated U. annulipes numbers by 37%, again with no differences between spring and neap tides. In Zanzibar 81% of N. meinerti burrows contained a crab. The instant visual count underestimated N. meinerti numbers by 41%, the continuous count, by 12%. Visual counts of S. guttatum in Zanzibar (Tanzania) underestimated crab numbers by 49%.Link_to_subscribed_fulltex

Geographic trends in mangrove crab abundance in East Africa

The aim of this work was to determine the abundance of crabs in mangrove communities along a latitudinal gradient along the eastern coast of Africa from 4°S to 32°S. Surveys were made at Mombasa (Kenya), Zanzibar (Tanzania), Maputo (Mozambique) and in the Transkei (South Africa). Crabs were estimated at three designated levels in the mangroves by visual census using a common protocol, and numbers were converted to biomass. Even after standardising the selection of sites and methods of census there was still extensive variability in the data, emphasising the complex heterogeneity of mangrove ecosystems. Lunar phase (full versus new moon springs) did not have a consistent effect on results, but shore height had several effects. Total crab biomass was similar in the two lower shore strata examined, but about twice as high at the top-Avicennia level. The ratio of grapsid biomass:ocypodid biomass also changed with height: from near unity in the lower mangrove, to 0.14 in the middle strata, but to 15 at the top. There was no consistent latitudinal trend in total crab numbers, but total crab biomass increased from north to south. In addition there was a consistent and marked change in the grapsid biomass:ocypodid biomass ratio: this swung from 0.65 at Mombasa to 6.8 in the Transkei. This has implications for the transfer of primary production through the food chain. Grapsids are important macrophagous feeders on the leaves and other parts of mangroves, whereas ocypodids are microphagous deposit feeders.Link_to_subscribed_fulltex