A proliferative disorder of possible hemic origin in the common cockle,Cerastoderma edule

A study is described concerning the infestation of a laboratory-reared Daphnia magna culture by the fungus Aphanomyces daphniae. The origin of this fungus is Lake Huron, Michigan, the water from which is used in the laboratory to culture daphnids and maintain fishes for toxicological testing. Infestations originate from the Lake during the autumnal and vernal homothermal periods. The fungus is apparently maintained in the laboratory in conjunction with the fishes. Onset of fungal infestations in zooplankton culture apparently is initiated by three types of stress: rising temperatures, declining dissolved oxygen values, and poor nutrition. These infections have been eliminated by separating the daphnid culturing facility from the fish facility, substituting an algal diet for a synthetic one, sterilizing all water, air, and glassware connected with zooplankton culture, and maintaining the daphnids in a constant temperature room with controlled dissolved oxygen levels in the culturing vessels.