DAO 108:227-239 (2014)  -  DOI: https://doi.org/10.3354/dao02695

Philometra floridensis (Nematoda: Philometridae) damages ovarian tissue without reducing host (Sciaenops ocellatus) fecundity

Micah D. Bakenhaster1,*, Susan Lowerre-Barbieri1, Yasunari Kiryu1, Sarah Walters1, Emma J. Fajer-Avila2

1Florida Fish and Wildlife Conservation Commission, Fish and Wildlife Research Institute, Florida 33701, USA
2Centro de Investigación en Alimentación y Desarrollo, A.C., Unidad Mazatlán en Acuicultura y Manejo Ambiental, CP 82010 Mazatlán Sinaloa, Mexico
*Corresponding author:

ABSTRACT: The parasitic nematode Philometra floridensis infects the ovary of its only host, the economically important fish species Sciaenops ocellatus, but the factors influencing host susceptibility and potential pathogenic effects are unknown. Here we report new information on these topics from evaluations of infected and uninfected hosts collected from the northeastern Gulf of Mexico. Fish length and age were evaluated vis-à-vis nematode prevalence to check for ontogenetic differences in host susceptibility. To evaluate health and reproductive consequences of infection, we looked for effects in Fulton’s condition factor (K) and batch fecundity estimates (BF), and we evaluated ovarian tissue histologically to check for oocyte atresia and other host responses. We observed localized pathological changes in fish ovarian tissue associated with female nematodes, including leucocytic exudates, granulomatous inflammation, and Langhans-type multinucleated giant cells; the hosts, however, appeared to maintain high fecundity and actually exhibited, on average, better health index scores and higher relative fecundity than did uninfected fish. These differences are likely explained by the parasite’s tendency to disproportionately infect the largest, actively spawning fish and by the localization of pathogenic changes, which could have masked effects that otherwise would have been reflected in mass-based health indicators. Although we did not detect negative effects on measures of overall health or reproductive output, further research is needed to better elucidate the relationship between these parasites and other factors affecting host reproductive potential, such as egg quality.


KEY WORDS: Red drum · Granulomatous inflammation · Multinucleate giant cells · Batch fecundity · Condition factor · Gonadosomatic index


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Cite this article as: Bakenhaster MD, Lowerre-Barbieri S, Kiryu Y, Walters S, Fajer-Avila EJ (2014) Philometra floridensis (Nematoda: Philometridae) damages ovarian tissue without reducing host (Sciaenops ocellatus) fecundity. Dis Aquat Org 108:227-239. https://doi.org/10.3354/dao02695

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