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Title: A study of digenean parasites from the salt marshes of North Norfolk.
Author: El-Mayass, Hanan.
ISNI:       0000 0001 3443 2723
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 1991
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Hanan El-Mayass, 1991. A study on digenean parasites from the salt marshes of North Norfolk. A survey of digenean parasites was conducted, particularly those utilizing the gastropod Hydrobia ulnae as a first intermediate host, on the salt marshes at Stiff key on the North Norfolk coast. Thirteen species belonging to the Notocotylidae , Microphallidae, Heterophyidae, Echinostomatidae and Gymnophallidae were identified and redescribed. A study of the seasonal occurrence of the most common digeneans in H. ulvae was conducted and considered in relation to the biology and behaviour of their hosts and the ecological conditions of their habitat. A study of the effect of these parasites on H. ulvae collected from the upper marsh and lower marsh was also conducted. The result of this study showed that the adult snails from the lower marsh are more infected than those from the upper marsh. There was no relationship between parasitism and sex of the snail and no parasite-induced gigantism was detected. The ultrastructure of the cyst wall and the in vitro excystation of three different species of metacercariae, namely, Cryptocotyle concavum, Bucephalus haimeanus and Microphallus Primas, were studied. C. concavum excysted most readily at 40- 42°C after pretreatment with acid pepsin in slightly alkaline solutions containing bile salts, but they also emerged in saline without treatment with enzymes or bile salts. There is evidence that glands in the anterior region are used to penetrate the cyst wall. B. haimeanus excysted in trypsin solutions at pH 7.8 at 20- 22°C. However, some metacercariae excysted and survived for more than 2h in 1% pepsin at pH 2.0. Bile salts failed to stimulate the metacercaria of B. haimeanus and played no part in excystation. Excystment of M. primas occurred only in trypsin solutions at pH 7.6 at 40-42°C. Egg production in the progenetic metacercaria of M. primas, was studied and its initiation was found to be temperature-dependent.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available
Keywords: Zoology