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Potential biological control agents for the european green crab, Carcinus maenas in Australian waters


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Gurney, RH 2006 , 'Potential biological control agents for the european green crab, Carcinus maenas in Australian waters', PhD thesis, University of Tasmania.

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Marine species are invading new ports and waterways threatening biological diversity
and contributing to environmental changes which are difficult to reverse or remediate.
The European green crab, Carcinus maenas (Linnaeus, 1758) is a successful invasive
marine species which has spread from Europe to adversely impact the marine
ecosystems of South Africa, and the continents of North and South America and
Australia. Methods for controlling this crab are sought and biological control is one
possible method.
This thesis examines the parasite fauna of native and introduced shore and near-shore
crabs from the temperate coastlines of Victoria, Flinders Island and Tasmania,
Australia, to search for potential biological control agents for the introduced
pestiferous European green crab, C. maenas. Collections were made from the intertidal
zone by hand and trap and from shallow sub-tidal (< 5m depth) zones using traps
set from boats. The study area surveyed both established populations (first recorded >
100 years ago) and recently arrived populations (first recorded 12 years ago).
This survey revealed a number of potential biological control agents against C.
maenas, including two species of trypanorhynch tapeworm, Dollfusiella martini
(Beveridge, 1990) and Trimacracanthus aetobatidis (Robinson, 1959), and a new
species of rhizocephalan. Field observations of high larval trypanorhynch loads in
individual C. maenas showed evidence of gross pathology which was histologically
studied and described. Physiological impairment of C. maenas was indirectly
examined through digestive enzyme analysis of the parasitised digestive gland.
Histology and digestive enzyme analysis revealed that C maenas with high intensity trypanorhynch infections suffered digestive gland damage and possibly impaired
digestive enzyme function.
Taxonomic relatedness of native hosts with C. maenas was shown to be more
important than ecological overlap for parasites to transfer to C. maenas.
Consequently, attempts were made to cross-infect green crabs with a rhizocephalan
found on the confamilial native crab, Nectocarcinus integrifrons (Latreille, 1825), in
the laboratory. These attempts failed, however, the unnamed rhizocephalan was
described and named as Sacculina nectocarcini, a congeneric to Sacculina carcini
(Thompson, 1836) — a well documented parasitic castrator of C. maenas in its native
European range.
An analysis of mitochondrial cytochrome oxidase I (COI) DNA of nominal S. carcini,
parasitising three species of portunid crab, revealed that S. carcini is capable of
parasitising at least two other species of portunid crab in addition to C. maeanas. The
use of S. carcini as a biological control agent must be treated with caution. COI
analysis proved to be a useful tool for resolving spatial heterogeneity of S. carcini. In conclusion, larval trypanorhynch tapeworms offer some potential for control
against C. maeans. However, the many unknown trophic links required to complete
the lifecycles of these parasites will make field application unpredictably difficult. S.
nectocarcini directly attacks its host, making field management as a biological
control agent simpler and more effective. The host specificity of this parasite needs to
be resolved to determine whether it will switch to C. maenas. The host specificity of S. carcini, a rhizocephalan parasitising C. maenas in its native range, is too lax for it
to be released safely in Australia.

Item Type: Thesis - PhD
Authors/Creators:Gurney, RH
Keywords: Carcinus maenas, Carcinus maenas, Carcinus maenas
Copyright Holders: The Author
Copyright Information:

Copyright 2006 the Author - The University is continuing to endeavour to trace the copyright owner(s) and in the meantime this item has been reproduced here in good faith. We would be pleased to hear from the copyright owner(s).

Additional Information:

Chapter 3 appears to be the equivalent of a postprint finally published as: Gurney, R. H.; Nowak, B. F.; Dykova, I.; Kuris, A. M., 2004, Histopathological effects of trypanorhynch metacestodes in the digestive gland of a novel host, Carcinus maenas (Decapoda), Diseases of aquatic organisms, 58(1), 63-69

Chapter 4 appears to be the equivalent of a preprint finally published as: Gurney, R. H.; Johnston, D. J.; Nowak, B. F., 2006, The Effect of parasitism by Trypanorhynch Plerocercoids (Cestoda, Trypanorhyncha) on the digestive enzyme activity of Carcinus Maenas (Linnaeus, 1758) (Decapoda, Portunidae), 79(6), 663-675

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