DAO prepress abstract  -  DOI: https://doi.org/10.3354/dao03168

Hematology and condition factor of tui chub and fathead minnow parasitized by nematode from Upper Klamath Lake, Oregon, USA

Maurício L. Martins*, Marcos Tavares-Dias, Andrew J. Janik, Michael L. Kent, Gabriela T. Jerônimo

*Email: mauricio.martins@ufsc.br

ABSTRACT: This study evaluated the haematological profile and condition factor (Kn) of tui chub Siphateles bicolor and fathead minnow Pimephales promelas and their associations with larvae of Contracaecum sp. infection of the heart. A total of 30 tui chub and 17 fathead minnow were collected from Upper Klamath Lake, Oregon, measured, weighed and blood drawn for hematological analysis. Nematode larvae parasitized tui chub with a prevalence of 50% and mean intensity 1.40, while 11.8% of fathead minnow were parasitized at mean intensity 1.0. Non-parasitized tui chub were significantly larger than the parasitized fish indicating that small fish could be easily predated by the definitive host, a piscivorous bird. Although the relatively large worm occupied a large portion of the atrium, the presence of the larvae did not affect tui chub Kn, possibly associated with low parasite intensity and a harmonic co-evolution. Only parasitized fathead minnow showed significant differences in RBC-measurements (greater cell-width, and larger nuclei) compared to non-parasitized fish. Lymphocytes were the most common white blood cells found in tui chub, followed by neutrophils, monocytes, and PAS-positive granular leukocytes; in fathead minnow lymphocytes were followed by heterophils, monocytes, neutrophils and eosinophils. This study is the first report of condition factor and the description of blood cells as well as haematological parameters in these fish species.