Intertidal zone management in the Western Indian Ocean: assessing current status and future possibilities using expert opinions

Abstract

This expert opinion study examined the current status of the intertidal zone in the Western Indian Ocean (WIO) and ranked and discussed future management approaches. Information was gathered from scientists, practitioners, and managers active in the WIO region through a questionnaire and a workshop. The experts stated that the productive intertidal environment is highly valuable for reasons such as recreation, erosion protection, and provision of edible invertebrates and fish. Several anthropogenic pressures were identified, including pollution, harbor activities, overexploitation, and climate change. The experts considered the WIO intertidal zone as generally understudied, undermanaged, and with poor or no monitoring. The most important management strategies according to the expert opinions are to develop and involve local people in integrated coastal zone management (ICZM), to increase knowledge on species-environment relationships, and to develop awareness campaigns and education programs. To improve coastal environmental management and conservation, we argue that the intertidal zone should be treated as one organizational management unit within the larger framework of ICZM.

Fig. 1

An intertidal zone covered with seagrass during low spring tide (tidal range 4 m, diurnal) in Zanzibar, Tanzania. Photo: Lina Mtwana Nordlund

Fig. 2

Map of the Indian Ocean (source www.d-maps.com). The WIO mainland coast is 13 000 km long and stretches from Somalia to South Africa and the island states have a coastline of 6360 km (UNEP/Nairobi Convention Secretariat and WIOMSA 2009)

Fig. 3

Distance between respondents’ area of work/interest. Each triangle in the MDS plot represents one expert’s background. The scattered pattern implies that most experts have different areas of work/interest compared to the other respondents; the longer the distance between experts in the plot, the larger the difference in areas of work/interest

Fig. 4

Average score for management strategies; scores = 1–4, where 1 = low and 4 = high; 0 = I do not know. The proxy (confidence/importance) for realistic management is given below each bar set in percent. The figure is arranged according to the “importance” score

Fig. 5

MDS plot showing respondents’ (R) answers on level of support for the different management strategies. Each dot represents one expert, and the assembly of dots in the plot implies that a great similarity of the experts’ level of support was found, but that some outliers were also present, i.e., some experts scored level of support differently than most experts