This week another paper by Régnier et al. (2015) appeared, that has the potential to become highly cited. It may be seen as a sequel on a previous paper about conservation issues (here), and focusses on Hawaiian land snails.
The abstract reads: “The International Union for Conservation of Nature (IUCN) Red List includes 832 species listed as extinct since 1600, a minuscule fraction of total biodiversity. This extinction rate is of the same order of magnitude as the background rate and has been used to downplay the biodiversity crisis. Invertebrates comprise 99% of biodiversity, yet the status of a negligible number has been assessed. We assessed extinction in the Hawaiian land snail family Amastridae (325 species, IUCN lists 33 as extinct). We did not use the stringent IUCN criteria, by which most invertebrates would be considered data deficient, but a more realistic approach comparing historical collections with modern surveys and expert knowledge. Of the 325 Amastridae species, 43 were originally described as fossil or subfossil and were assumed to be extinct. Of the remaining 282, we evaluated 88 as extinct and 15 as extant and determined that 179 species had insufficient evidence of extinction (though most are probably extinct). Results of statistical assessment of extinction probabilities were consistent with our expert evaluations of levels of extinction. Modeling various extinction scenarios yielded extinction rates of 0.4-14.0% of the amastrid fauna per decade. The true rate of amastrid extinction has not been constant; generally, it has increased over time. We estimated a realistic average extinction rate as approximately 5%/decade since the first half of the nineteenth century. In general, oceanic island biotas are especially susceptible to extinction and global rate generalizations do not reflect this. Our approach could be used for other invertebrates, especially those with restricted ranges (e.g., islands), and such an approach may be the only way to evaluate invertebrates rapidly enough to keep up with ongoing extinction”.
While this result is appealing (or more properly put ‘horrifying’), it needs to be seen that similar data are available for other areas. Hawaii is an island group which is relatively well surveyed, and with sufficient malacological expertise available for field work and subsequent expert judgement of the results. Other areas of interest may be lacking one or more of these factors.
When I chatted with one of the co-authors, Carl Christensen, he added as his personal opinion “I “met” my first Achatinella tree snail and a few amastrids in 1962, when I was in high school and had a summer job as a curatorial assistant in Bishop Museum’s Malacology division. The then-curator, Dr. Yoshio Kondo, took his crew of a half-dozen or so eager kids on weekend field trips into the mountains to acquaint us with Hawaii’s native snails and other flora and fauna. Achatinella (and a few amastrids) could still be found in fair numbers in favored locations and at reasonably low elevations on Oahu (ca. 1250 ft and higher). Those Achatinella populations and many of the species we saw then are now extinct; the Amastridae have had an even harder time of it. Between federal, state, and private agencies there are now a fair number of conservation workers interested in snails here in Hawaii, and there are some serious efforts underway to try to do something about the problem (…) In 1962, Euglandina had only recently arrived, and it has probably been the main instrument of destruction since that time. It’s a sad task–as I’ve often said, to be a biologist in Hawaii is to live in constant pain as you watch your favorite critters go extinct. (…) The paper pushes the message that to demand the same standards of data completeness for analysis of the conservation status of tropical invertebrates that has traditionally been used for much better known “charismatic megafauna” means that we will inevitably vastly underestimate the threat to these “lesser” species. Our data base for Hawaii is definitely imperfect, but it has real value and can be used to extrapolate to other areas as long as we don’t demand the same level of data comprehensiveness that is available to students of vertebrates.”
Hopefully this study will not remain unnoticed in the field of conservation.
Regnier, C., Bouchet, P., Hayes, K.A., Yeung, N.W., Christensen, C.C., Chung, D.J.D., Fontaine, B. & Cowie, R.H., 2015. Extinction in a hyperdiverse endemic Hawaiian land snail family and implications for the underestimation of invertebrate extinction. – Conservation Biology (advance access) DOI: 10.1111/cobi.12565