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I studied the effects of Polymorphus paradoxus Connell and Corner and Polymorphus marilis Van Cleave on colour and carotenoid quantities of their host amphipod Gammarus lacustris G.O. Sars in seven lakes in Alberta, Canada, that differed in productivity. Polymorphus marilis induced pigmentation dystrophy and a higher degree of blueness in both amphipod sexes than did P. paradoxus. Colour shifted toward lighter, bluer and greener tones, denoting less carotenoids, in amphipods parasitized by P. marilis. This is the first study to measure host-colour changes induced by parasites using consistent, repeatable digital analysis. Maximum carotenoid quantities were reached in hypereutrophic lakes where parasite-induced colour changes were also generally minimal. I developed regression models that accurately predict carotenoid quantities in amphipods by their colour, parasite status and water chemistry. This is the first study showing that carotenoid quantities and parasite-induced colour change in crustaceans depend on lake productivity. / Ecology

I studied the effects of Polymorphus paradoxus Connell and Corner and Polymorphus marilis Van Cleave on colour and carotenoid quantities of their host amphipod Gammarus lacustris G.O. Sars in seven lakes in Alberta, Canada, that differed in productivity. Polymorphus marilis induced pigmentation dystrophy and a higher degree of blueness in both amphipod sexes than did P. paradoxus. Colour shifted toward lighter, bluer and greener tones, denoting less carotenoids, in amphipods parasitized by P. marilis. This is the first study to measure host-colour changes induced by parasites using consistent, repeatable digital analysis. Maximum carotenoid quantities were reached in hypereutrophic lakes where parasite-induced colour changes were also generally minimal. I developed regression models that accurately predict carotenoid quantities in amphipods by their colour, parasite status and water chemistry. This is the first study showing that carotenoid quantities and parasite-induced colour change in crustaceans depend on lake productivity. / Ecology

I studied the effects of Polymorphus paradoxus Connell and Corner and Polymorphus marilis Van Cleave on colour and carotenoid quantities of their host amphipod Gammarus lacustris G.O. Sars in seven lakes in Alberta, Canada, that differed in productivity. Polymorphus marilis induced pigmentation dystrophy and a higher degree of blueness in both amphipod sexes than did P. paradoxus. Colour shifted toward lighter, bluer and greener tones, denoting less carotenoids, in amphipods parasitized by P. marilis. This is the first study to measure host-colour changes induced by parasites using consistent, repeatable digital analysis. Maximum carotenoid quantities were reached in hypereutrophic lakes where parasite-induced colour changes were also generally minimal. I developed regression models that accurately predict carotenoid quantities in amphipods by their colour, parasite status and water chemistry. This is the first study showing that carotenoid quantities and parasite-induced colour change in crustaceans depend on lake productivity. / Ecology

The Pacific Mole crab Emerita analoga is a filter-feeding crustacean inhabiting sandy beaches along the western coasts of North and South America. The tissues of E. analoga contain carotenoids, dietary pigments that are involved in crustacean cryptic coloration and egg development. Despite extensive study of its life history, little is known about how E. analoga is affected by parasitism, even though previous groups noted the presence of larval helminths in its body cavity. We examined parasite prevalence and intensity of the acanthocephalan Profilicollis altmani infecting E. analoga from Pismo Beach, California. We investiged the effects of parasite infection and body size on egg production as well as the effects of parasite infection, body size, season and reproductive condition on tissue carotenoids. We also analyzed P. altmani cystacanths for carotenoids to determine if parasite acquisition of host carotenoids was possible. Infection by P. altmani did not affect the carotenoid concentration or content of any E. analoga tissues. Egg mass production was also unaffected by infection. Crab body size was the only significant predictor of carapace and egg carotenoid concentration, while reproductive season significantly affected ovarian carotenoid concentration. P. altmani cystacanths contained carotenoids similar to those found in E. analoga tissues, but we could not determine if acquisition was purposeful or from a specific tissue. E. analoga esophagus tissue was analyzed for the first time during this study and contained predominantly astaxanthin.