Albert K. Sparks

A ciliate infection (Paranophrys sp.) in laboratory-held Dungeness crabs, Cancer magister.

Abstract A ciliate infection ascribed to the genus Paranophrys was found in early adult Dungeness crabs, Cancer magister, held in laboratory bioassay facilities, and in outdoor flow-through tanks in Newport, Oregon. Infections proved lethal as ciliates multiplied to high densities in the blood and tissues causing degeneration and necrosis of musculature. All infected crabs had recent wounds through the exoskeleton which probably provided a portal of entry, and the elapsed time between infliction of a wound and gross symptoms of stress was estimated at 9 days although animals died as late as 26 days. The nature of Paranophrys infections in C. magister, i.e., as an opportunistic pathogen of cultured animals and/or a disease in wild populations of this crab is discussed.

Observations on the histopathology of a systemic ciliate (Paranophrys sp.?) disease in the Dungeness crab, Cancer magister

Abstract Infections of the hemolymph of crabs by ciliates have been known for almost a century. Originally placed in the genus Anophrys , these crab-parasitizing ciliates have been recently transferred to the genus Paranophrys . Infections were long thought to be confined to the hemolymph in living crabs, with death caused by consumption of all hemocytes. Histological examination of heavily infected, but living, Dungeness crabs demonstrate that the ciliates actively invade and probably consume many tissues of the host prior to death rather than saprophytically feeding on the decomposing tissues subsequent to death as previously reported.

A systemic microbial disease in the Dungeness crab, Cancer magister, caused by a Chlamydia-like organism

Abstract A Chlamydia-like agent was diagnosed in Dungeness crabs, Cancer magister, collected from Willapa Bay and northern Puget Sound, Washington. Over a 5-year period, infected crabs were found during the months of December through March. Infection by the organism is systemic, resulting in greatly hypertrophied cells with appressed nuclei. Unlike Chlamydia or other Chlamydia-like organisms, the present microbe has a great affinity for connective tissue or connective tissue cells rather than epithelial cells. Transmission electron microscopy revealed the presence of several developmental stages that are similar to chlamydial stages, in addition to what appear to be slightly altered or aberrant stages.

Host response in the white shrimp, Penaeus setiferus, to infection by the larval trypanorhynchid cestode, Prochristianella penaei

Abstract White shrimp, Penaeus setiferus, infected by the plerocercoid larva of the trypanorhynchid cestode, Prochristianella penaei, respond to infections in the heptaopancreas by developing a progressively denser cyst, composed of hemocytes, fibroblasts, and collagenlike fibers, around the parasite. The pleocercoid is eventually destroyed and resorbed leaving a dense fibrous capsule in the hepatopancreas. Worms in the adjacent hemocoel are encapsulated by a thin host cyst and a less intense infiltration of cells and deposition of fibers, insufficient to destroy the pleroceroid. It is believed that the resorption process explains the drop in intensity of infection in juvenile white shrimp after a certain size is attained.

A preliminary study of idiopathic lesions in the Dungeness crab, Cancer magister, from Rowan Bay, Alaska

Seventeen Dungeness crab, Cancer magister, from a Log Transfer Facility (LTF) in Rowan Bay, Alaska, were examined in a histopathological study because of what appeared to be high prevalences of shell disease that typically involved periopod, arthrodial membranes. Dungeness crab (N = 9) from a reference site in Rowan Bay were later examined. The severity and prevalence of the most frequently observed idiopathic lesions, melanized nodules and granulomas, in both groups were statistically tested. This paper reports the findings of this preliminary study.

PRELIMINARY REPORT ON THE DISEASES AND PARASITES OF JUVENILE WALLEYE POLLOCK, THERAGRA CHALCOGRAMMA, FROM THE GULF OF ALASKA

ABSTRACT: In 1986, a baseline survey was begun to investigate the possible role of parasites and diseases as regulators of wild, commercially important fish populations. Juvenile walleye pollock, Theragra chalcogramma , were chosen because much is known about their growth rate, life history, and distribution. A total of 142 fish were collected in 1986, and 726 in 1987.