Home
Research Projects
CV
Cowie Lab Homepage
|
|
Research Projects
The invasive predatory snail, Oxychilus
alliarius, was first recorded in the Hawaiian Islands in 1937
and is currently on six of the main Islands (Kauai, Oahu, Maui, Molokai,
Lanai, and Hawaii; unpublished data). Oxychilus alliarius, also known
as the garlic snail, is native throughout Central-Western Europe,
Iceland and the British Isles. Its prey is other snails. There are
no native Oxychilus species in Hawaii. In the 1980s, many O. alliarius
were found in forests of Haleakala and the West Maui mountains, and
in these locations there was a noticeable absence of native ground-dwelling
snails.
The overall goal of the proposed research is to assess the potential
impact of O. alliarius on Achatinella species in Hawaii
through the assessment of the current distribution of O. alliarius,
potential for its continued spread, and estimates of population density
in locations in or around areas designated as Achatinella species
habitat. During previous alien snail and slug surveys conducted by
Dr. R.H. Cowie and members of his lab (Dr. N.W. Yeung, Dr. K.A. Hayes,
J.R. Kim, and others), funded by the USDA Cooperative Agricultural
Pest Surveys (CAPS; 2004 - 2010), we began to monitor the potential
rate of spread of a newly discovered population of O. alliarius
located on Army controlled land on the summit of Mt. Kaala and
in the vicinity of the Mt. Kaala Natural Area Reserve (NAR). Preliminary
data from monthly surveys conducted since 2009 indicate that O.
alliarius is spreading further into the NAR and that the biodiversity
of native Hawaiian snails has declined where the garlic snail is present.
Continued monitoring is necessary to understand the role of O.
alliarius in the decline of native snail diversity, and results
of such studies will provide managers with a better understanding
of the threat O. alliarius poses to Hawaii’s native snail
fauna, specifically the endangered Achatinella species. Additionally,
such studies will help us better manage spreading populations of O.
alliarius and provide clues as to how it may be eliminated or
at least how to implement some damage mitigation. Future work stemming
from the proposed study will be geared towards developing these control
methods and will be the subject of future funding requests.
The Hawaiian land
snail fauna is arguably the most diverse in the world in relation
to land area: >750 recognized species in only 10 families. Although
certain groups were revised and studied during the early 20th century,
subsequent decades were considered a period of malacological silence
regarding Hawaiian land snails. However, conservation efforts led
in 1981 sparked renewed interest in the subfamily Achatinellinae
that led to the listing of the entire genus Achatinella as endangered.
With the other 87% of Hawaii's land snails, no significant ecological
or evolutionary studies (e.g. life history and population assessments,
systematic/taxonomy, and molecular diversity) have been completed
and it is hard to assess the number of species now extinct. Estimates,
primarily extrapolated from studies of the Hawaiian Tree snail subfamily
Achatinellinae, indicate that as much as 50-90% of Hawaii's land
snail fauna are lost. These extinctions have been primarily driven
by habitat destruction and impacts of invasive species.
The lack of taxonomic clarity and dearth of recent studies of the
Hawaiian land snails hinders attempts to accurately assess their
conservation status. The goals of this project are to:
1. Complete a comprehensive and systematic survey of the Hawaiian
land snail fauna.
2. Develop comprehensive phylogenetic hypotheses for all Hawaiian
land snail species using material from the surveys in goal 1 and
the extensive museum material available.
3. Completely update the taxonomic framework of Hawaiian land snails
using an integrated phylogenetic and morphological approach, and
describe/redescribe taxa as necessary.
|