Population-Dynamics Of Mytilicola-Intestinalis In Mytilus-Edulis In South West England

The population dynamics of Mytilicola intestinalis Steuer in mussels (Mytilus edulis L.) from the River Lynher, Cornwall, England, have been studied over 3 years. By transplanting uninfested mussels from the River Erme, South Devon, into the Lynher mussel bed, the study was extended to the growth and development of new infestations under natural conditions. Female Mytilicola intestinalis are shown to breed twice, and two generations of parasites coexist for most of the year, with recruitment taking place in summer and autumn. One generation contributes its first brood to the autumn recruits before overwintering and contributing its second brood to the following summer's recruits. The other generation overwinters as juvenile and immature stages to contribute its two broods successively to the summer and autumn recruits. Environmental temperatures are believed to control the rates of development at all stages rather than acting as triggers in the onset or cessation of breeding at specific times. There is no evidence to support the contention that heavily infested mussels are killed, and parasite mortality is shown to be density-independent.

Cytology And Cytochemistry Of Hemocytes Of Mytilus-Edulis And Their Responses To Experimentally Injected Carbon Particles

Hemocytes of Mytilus edulis were examined cytologically and cytochemically. On the basis of structure, staining reactions, and phagocytic behavior, they were divided into two main groups: basophilic hemocytes and eosinophilic granular hemocytes (granulocytes). The basophilic cells were further divided into small lymphocytes and larger phagocytic macrophages reactive for lysosomal hydrolases. Mitosis was observed in granulocytes and in small lymphoid cells, believed to be the stem cells for the basophilic cell line. A few cells appeared to be intermediate between lymphocytes and small granulocytes. Macrophages were the main cell type involved in the clearance of injected carbon particles. However, granulocytes did show some phagocytic activity. Brown cells displaying apparent amoebocytic behavior were found to contain Fe3+ and Pb2+ in cytoplasmic inclusions, some of which were also reactive for β-glucuronidase and glucosaminidase. These cells appear to have a separate origin from the hemocytes.

Quantitative Cytochemical Effects Of 3 Metal-Ions On A Lysosomal Hydrolase Of A Hydroid

The quantitative effects of Cu8+, Cd2+ and Hg2+ on the cytochemical staining reaction for lysosomal N-acetyl-/?-D-glucosaminidase have been determined and related to the inhibitory effects of the metals on colonial growth rate in the experimentally cultured hydroid Campanularia flexuosa. Cytochemical threshold concentrations are comparable to known environmental levels and are about one order of magnitude lower than those obtained by measuring colony growth rates. Pretreatment of colonies with Cuz+ gave no indication of tolerance adaptation, although there is evidence of the cumulative toxicity of Cu2+ and the possible sequestration of this metal in endodermal cell lysosomes. There is also an indication that the Cu2+ may exert its toxic effect by decreasing the stability of the lysosomal membranes, thus increasing the level of free glucosaminidase activity.