Preliminary re-survey of the land snail fauna of Rotuma: conservation and biosecurity implications.

Abstract

In May 2012 Rotuma Island, the main island of the remote Rotuma Group (Fiji), was surveyed to document the composition of the non-native land snail fauna and to investigate if populations of previously recorded native land snail species persist. From sampling at nine locations, twenty-one land snail species from eleven gastropod families were found. Of these, eight species are non-native and two of these Parmarion martensi Simroth, 1893 and Quantula striata (Gray, 1834) (Ariophantidae) are new records for the Rotuma Group. Ten of the 13 species of native land snails found — including the endemic partulid Partula leefi E. A. Smith, 1897 and the rhytidid Delos gardineri (E. A. Smith, 1897) — were detected only as empty shells. The native Ouagapia perryi (E. A. Smith, 1897) and the endemic Succinea rotumana E. A. Smith, 1897 and Sinployea rotumana (E. A. Smith, 1897) remain undetected on Rotuma Island since their first collection in 1897. The non-native, invasive predatory flatworm, Platydemus manokwari, was also found and represents a major threat to the island’s land snail fauna. This non-native species appears to be absent in many other parts of the Fiji Island archipelago and thus a re-evaluation of existing quarantine measures is required to address its potential spread to non-invaded areas. Comparisons with earlier surveys indicate a shift in the structure of the Rotuman land snail fauna over a 115-year period, with declining native components and increasing prevalence of non-native species. Further sampling, focusing on residual native habitat in less accessible areas such as coastal cliffs and offshore islets, is urgently needed to establish the conservation status of Rotuman native land snails and determine the threat posed by both, non-native snails and P. manokwari.

The invasive New Guinea flatwormPlatydemus manokwariin France, the first record for Europe: time for action is now

“…The flatworm has been accidentally introduced, probably together with plants and soil, to various islands in the Pacific region including Australia, Guam, Palau, Hawaii, Federated States of Micronesia, French Polynesia, and Samoa. The most recent report of P. manokwari in the Pacific region is its occurrence in Rotuma in the Fiji archipelago ( Brodie et al, in press ). The flatworm was also deliberately introduced as a bio-control agent for the Giant African Snail Achatina fulica to Bugsuk in the Philippines ( Muniappan et al, 1986 ; Waterhouse & Norris, 1987 ), Yokohama, Japan ( Eldredge & Smith, 1995 ), and the Maldives ( Muniappan, 1987 ).…”

Evolution and Extinction of Land Snails on Oceanic Islands

“…It preys heavily on land snails, including arboreal species (Sugiura et al 2006, Sugiura & Yamaura 2010, Ohbayashi et al 2007). It has become a serious threat to the native snail faunas of the Mariana Islands (Hopper & Smith 1992, Eldredge & Smith 1995, Régnier et al 2009) and Samoa (Cowie & Robinson 2003), and it is present on many other islands and archipelagos, including Palau (Eldredge & Smith 1995), Pohnpei in the Federated States of Micronesia (Eldredge & Smith 1995), the Philippines (Muniappan et al 1986), Tonga and Vanuatu (Anonymous 2002), Fiji (Brodie et al 2014), and Mangareva in French Polynesia (Winsor et al 2004). Although it has been introduced to the Hawaiian Islands (Eldredge & Smith 1995), it has not become widespread or abundant (S. Sugiura, personal communication), and its impacts on the native snail fauna may not as yet have been great.…”

Peer Review #1 of "The invasive New Guinea flatworm Platydemus manokwari in France, the first record for Europe: time for action is now (v0.1)"

“…The flatworm has been accidently introduced, probably together with plants and soil, to various islands in the Pacific region including Australia, Guam, Palau, Hawaii, Federated States of Micronesia, French Polynesia, and Samoa. The most recent report of P. manokwari in the Pacific region is its occurrence in Rotuma in the Fiji archipelago (Brodie et al 2013). The flatworm was also deliberately introduced as a bio-control agent for the Giant African Snail Achatina fulica to Bugsuk in the Philippines (Muniappan et al 1986;Waterhouse & Norris 1987), Yokohama, Japan (Eldredge & Smith 1995), and the Maldives (Muniappan 1987).…”