Priority sites for conservation of land snails in Gabon: testing the umbrella species concept

Abstract

In order to assess the potential for molluscan conservation of a protected area considered representative of regional megafauna, we sampled molluscs inside and outside Lopé National Park in Gabon. In the northern part of Lopé National Park, 116 stations were surveyed and 71 species collected. Outside the park, 37 stations yielded 96 species, including 71 in Lastoursville, a small limestone area where molluscs are significantly more abundant than in other collecting sites. Lastoursville is among the richest sites known for molluscs in Africa. Overlap between sampling areas was limited, with 20.0% of the species found only in Lopé National Park, and 40.8% of the species found only outside. This suggests that Lopé National Park does not protect the whole molluscan diversity of central Gabon. Given the high levels of allopatric diversity of tropical land snails, conservation strategies cannot be the same for snails and for wide‐ranging vertebrates. Protecting small areas with a high abundance and diversity of molluscs would be less expensive and as efficient for molluscan conservation as protecting large tracts of rainforest. Despite limited general knowledge of central African molluscs, robust estimates of site‐specific diversity can be produced. Limestone areas harbour a remarkable biodiversity: sites such as Lastoursville would be ideal candidates for small protected areas dedicated to the conservation of land snails, and would complement the role of large protected areas.

Seashore in the mountain: limestone-associated land snail fauna on the oceanic Hahajima Island (Ogasawara Islands, Western Pacific)

“…Land snail fauna with high species richness and high endemism are generally associated with limestone outcrops in tropical regions (Schilthuizen et al ., 2005; Clements et al ., 2006; Fontaine, Gargominy & Neubert, 2007). Calcium‐rich substrates generally support a larger number of individuals and species of land snails than calcium‐poor substrates (Graveland et al ., 1994) because land snails have high calcium requirements for the production of both their eggs and their shells.…”

A simplified method for conducting ecological studies of land snail communities in urban landscapes

“…The two largest fractions were thoroughly searched with the naked eye and the third was sorted under a dissecting microscope. Since it is considered that no adult terrestrial molluscs are smaller than 0.6 mm, the smallest fraction was discarded (Tattersfield 1998;De Winter and Gittenberger 1998;Fontaine et al 2007a). Shells of juveniles (i.e.…”

Predicting rarity and decline in animals, plants, and mushrooms based on species attributes and indicator groups

“…Others have compared the overlap of diversity hotspots between species groups (Reid ; Heino ; Fontaine et al. ). If trends or hotspots coincided, one could thin out the number of species groups that need to be taken into account for information on the need and progress in conservation actions.…”

“…In an effort to test the issue of representativeness, some authors have examined whether trends in one species group were similar to those in other species groups (Thomas et al 2004). Others have compared the overlap of diversity hotspots between species groups (Reid 1998;Heino 2002;Fontaine et al 2007). If trends or hotspots coincided, one could thin out the number of species groups that need to be taken into account for information on the need and progress in conservation actions.…”