Abstract

Months after collection from San Francisco Bay, a group of Bay pipefish (Syganthus leptorhynchus) maintained at Underwater World at Pier 39 in San Francisco began to suffer sporadic, sub-acute mortality despite completion of a quarantine protocol, excellent growth, and apparent good health. External examination of mortalities revealed adult pipefish in excellent body condition, with no discernible external parasitism or other signs of disease. Gross necropsies revealed slender thread-like nematodes located in the heart and pericardial cavities of some individuals. Histologic examination demonstrated intra-luminal gravid female parasites in the sinus venosus, renal, and hepatic veins. Parasitism was not associated with pathologic changes to the walls of the sinus venosus or veins in five pipefish examined histopathologically. However, nematode larvae surrounded by lymphohistiocytic infiltrates were located in the interstitium of gill filaments and lamellae in 1 of 5 pipefish. Intercurrent protozoal coelomitis, dermatitis, and encephalitis (compatible with Uronema spp.), as well as hepatic lipidosis, were present in two, while skeletal muscle fiber degeneration and necrosis were observed in three of the five pipefish. Further morphologic examination of preserved whole worms indicated that the intra-luminal nematode belongs to the super family Dracunculoidea, family Daniconematidae. The nematode, which appears to be of low pathogenicity to the host under normal circumstances, has provisionally been classified as a new genus and new species.

The full manuscript is currently in review (Journal of Parasitology).

Acknowledgements

The authors would like to acknowledge all Underwater World at Pier 39 husbandry and life support staff involved with the collection and maintenance of the pipefish. The authors also wish to thank Spencer Russell, Michael Goedken, and Elizabeth Hendricks for their assistance with necropsies and histopathology. This is contribution number 2006 from the Storrs Agricultural Experiment Station. This study was partly supported by grant number A6022901 from the Grant Agency of the Academy of Sciences of the Czech Republic. Finally, thanks to Sarah Poynton for her suggestion of this collaboration.