Date of Award

Spring 1987

Project Type

Dissertation

Program or Major

Zoology

Degree Name

Doctor of Philosophy

Abstract

A study was conducted of parasites from the yellowtail flounder, Limanda ferruginea (Storer, 1839) taken from the western North Atlantic, United States. Monthly studies, from the Cape Ann, Massachusetts area, April 1977 to 1979, were initiated to determine prevalence, mean intensity, and range of parasites in relation to host and environmental factors. A second study was conducted to determine parasite-mix between the Cape Cod and the Georges Bank subareas, including preliminary findings from the southern New England and the Middle Atlantic subareas. From 40 previously reported parasites, including adults, metacercariae, plerocercoids, and juvenile forms, a total of 15 species of parasites were collected, including three new host records.

The Cape Ann study area was characterized by inshore related parasite species associated with a littoral or sublittoral area: Cryptocotyle lingua, Podocotyle sp., Fellodistomum furcigerum, Bothrimonus sturionis, and Echinorhynchus gadi. Relationships between parasite prevalence and environmental factors varied considerably. Seasonal periodicity was exhibited for water temperatures. The host age-parasite prevalence relationship also varied considerably. During Age I of the host, S. vetustum and the nematodes were the dominate parasite species. Hosts Age VII and greater displayed variable parasite prevalences.

The metacercariae of Cryptocotyle lingua found embedded in the yellowtail flounder were significantly more prevalent along the northern than along the southern Massachusetts coast. These metacercariae also displayed significant prevalence differences between study years, suggesting a high degree of variability from year to year. Prevalences of C. lingua discriminated local "aggregates" of yellowtail flounder isolated on Stellwagen Bank, Massachusetts Bay, from inshore "aggregates" along the northern Massachusetts coast.

Comparisons of the parasite-mix of the yellowtail flounder from the various subareas--Cape Cod, Georges Bank, southern New England, and Middle Atlantic, revealed differences in both the number of parasites and the degree of infestation. These differences may be attributed to host variation in habitats and feeding habits.

Further analyses used the mathematical procedures of the Coefficient of Community and the Percentage Similarity of Community tested for "communities" within the Cape Cod and Georges Bank subareas. Clusters of similarity index values of association equations revealed two major communities, including some lower intermediate affinity communities.

Geostatistical techniques were used to produce isocontour charts of selected dominant parasites from the Cape Cod and Georges Bank area.

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