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The main purpose of describing hotspots is to emphasize spatial variation in the value of biodiversity. As the locations of biodiversity hotspots describe areas of relatively high value, they are often used to guide conservation policy and planning.
Defining biodiversity hotspots
A biodiversity hotspot is an area with a relatively high biodiversity value. The idea of defining hotspots is generally credited to the ecologist Norman Myers, who suggested that global conservation efforts should be concentrated in areas where there were high numbers of endemic species and the threat to those species was high. The reasoning behind this approach is that the most cost effective way of reducing species extinctions is to focus resources on saving centres of threatened endemic species.
The areas that are compared to describe hotspots may be restricted by region or habitat. Examples include marine biodiversity hotspot, global biodiversity hotspot, estuarine biodiversity hotspot, European marine biodiversity hotspot.
Other measures for hotspots
The measure of biodiversity used to define hotspots is not limited to rarity, endangered status or endemicity. In regional studies a measure of species richness may be more common.
Global marine hotspot assessments
The hotspots approach advocated by Myershas been applied to coral reefs. Distribution records of 3235 species of fish, coral, snails and lobsters were used to identify 18 centres of endemism. A total of ten of these centres were defined as hotspots as they were at a greater threat of extinction. The ten hotspots were South Japan, the Gulf of Guinea, the North Indian Ocean, Eastern South Africa, Cape Verde Islands, West Caribbean, Red Sea, Philippines, South Mascarene Islands and the Sunda Islands.
Open ocean hotspots have been defined using data associated with long line fisheries. This analysis identified areas of high species richness in warmer oxygenated water – particularly in the south eastern Pacific Ocean, south of the Hawaiian Islands, east of Sri Lanka and off the eastern coasts of Australia and the U.S.A.
The development of global marine hotspot assessments has been limited by the coverage of data. Programmes such as the Census of Marine Life are intended to address such gaps. With the growth of marine biodiversity infrastructure, there is likely to be a period of rapid expansion in the understanding of marine biodiversity hotspots.
Regional and local hotspots
Hotspots at regional scales may be used to guide conservation policy and recommendations. The criteria for some, although not all, marine protected area selection processes include a measure of the relative richness, rarity and/or threat. The finer scale of spatial analysis for regional studies places further demands on the available data. There are no accepted criteria for deciding how much of a deviation from the average biodiversity for a region is needed for an area to qualify as a hotspot.
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- Attrill et al. 1996. An estuarine biodiversity hotspot. Journal of the marine biological Association of the UK. 76, 161-175.
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