Data/hora: 24/05/2024 01:59:55

Biblioteca(s): | Embrapa Florestas.
Data corrente: | 03/10/2008
Data da última atualização: | 03/10/2008
Autoria: | HASEGAWA, M.; SUGIURA, S.; ITO, M. T.; YAMAKI, A.; HAMAGUCHI, K.; KISHIMOTO, T.; OKOCHI, I.
Título: | Community structures of soil animals on Chichijima island in Ogasawara islands in relation to the survival of land snails.
Ano de publicação: | 2008
Fonte/Imprenta: | In: INTERNATIONAL COLLOQUIUM ON SOIL ZOOLOGY, 15; INTERNATIONAL COLLOQUIUM ON APTERYGOTA, 12., 2008, Curitiba. Biodiversity, conservation and sustainabele management of soil animal: abstracts. Colombo: Embrapa Florestas. Editors: George Gardner Brown; Klaus Dieter Sautter; Renato Marques; Amarildo Pasini. 1 CD-ROM.
Idioma: | Inglês

Conteúdo:

Chichijima in Ogasawara (Bonin) Islands is located in the northwestern Pacific Ocean, about
100km south of the mainland of Japan. 95 species of land snails have been recorded from
these islands, and of which more than 90 percent are endemic to the islands (Chiba eta al.
2007). Most of the endemic species, however, have already become extinct or endangered in
Chichijima (Chiba eta al. 2007). Predation pressure by an invasive flatworm (Platyrdemus
manokwari) on the land snails was suggested as one of the cause of the decline of snails
(Ohbayashi et al. 2005, 2007, Sugiura et al. 2006). Soil fauna on Chichijima were investigated
several times (Aoki and Harada 1978 and Ishizawa and Takehara 2001), but the related studies
with decline of snails have not been conducted. The aim of this study was to investigate the
relation of soil fauna with survival of land snails from the comparison of soil fauna on snail surviving
and extinct areas of Chichijima Island.
The research was conducted in June and November of 2005. Ten sites (3 snail surviving sites
and 7 extinct sites) for soil macrofauna and six sites (3 snail surviving sites and 3 extinct sites)
for soil mesofauna were set. Sampling of soil macrofauna was conducted at six quadrates
(each 25 × 25 cm) set at 5 m intervals along a line (25 m) in each site. Litter layer and topsoil (15
cm deep) were collected at each quadrate. Soil macrofauna was immediately picked up from
the soil and litter by hands. Soil mesofauna was extracted from the soil core samples. A 100 ml
soil sample (20 cm2 × 5 cm in depth) including litter layer was taken by a cylindrical core sampler
at each of the ten points set at 5 m intervals along another line (45 m) in each site. Soil mesofauna
was extracted from the samples for three days at 35?? by Tullgren funnels.
Most of soil fauna did not show the decline. However, one undescribed but endemic carabid
species (Badister sp.), which have selective feeding habits on land snails, was not recorded on
snail extinct area. Earthworm was recorded at all study sites, and dominant in soil macrofauna.
All species of the earthworms seemed to be introduced species. The invasive flatworm P.
manokwari has been reported to feed also on the carcasses of earthworms as well as live
snails, therefore P. manokwari is expected to survive on most of the area of Chichijima Island.
Comaparison of this examination with Aoki and Harada (1978) showed that the density of
Isopods decreased. The density and species richness of ants, Collembola and oribatid mites
were not so different between snail survived and exterminated area.
In conclusion, the close relation between soil fauna and land snails has been rarely recognized
except one carabid species, but the present (current) structure of soil animals as reflected in
introduced earthworm, decline of endemic isopods and tramp species of ants indicated the
various impacts on the fauna on Chichijima island.

Categoria do assunto: | --
Registro original: | Embrapa Florestas (CNPF)
Exemplares: | CNPF - (43799-1) - UPE - PL - -- - CD0305 -  -  - DIS