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Seasonality of immunological and health-state parameters of wild broadnose sevengill shark, Notorynchus cepedianus

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Sueiro, MC, Awruch, CA ORCID: 0000-0003-0047-7848, Irigoyen, AJ, Argemi, F and Palacios, MG 2018 , 'Seasonality of immunological and health-state parameters of wild broadnose sevengill shark, Notorynchus cepedianus' , Physiological and Biochemical Zoology, vol. 92, no. 1 , pp. 24-36 , doi: 10.1086/700573.

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Abstract

Seasonal fluctuation in environmental parameters can influenceimmune responses of vertebrates and consequently influencetheir health and disease resistance. Although seasonalityof immune function is well documented in a broadrange of vertebrate taxa, this information remains virtuallyunexplored in cartilaginous fish. Here we examine seasonalvariation in immune and general-health parameters of free livingadult broadnose sevengill sharks, Notorynchus cepedianus,along an annual cycle. We sampled sharks duringautumn/winter (i.e., coolest temperatures and nonreproductiveperiod) and spring/summer (i.e., warmest temperaturesand active reproductive period) and assessed aspects of immunity,general condition, and reproductive hormone levels.A seasonal influence was observed in some, but not all, parametersevaluated. Lower lymphocyte counts and higher heterophilcounts and granulocyte to lymphocyte (G∶L) ratios wereobserved in sharks sampled during autumn/winter than in thosesampled during spring/summer. On the other hand, total leukocytecounts, eosinophil counts, bacterial agglutination mediatedby natural antibodies, and hematocrit did not vary seasonally.The observed seasonal patterns could be explained as (1) greater levels of stress based on the G∶L ratio, (2) a sign of immunosuppressionor depressed immune investment based on the lowlymphocyte counts, and/or (3) a sign of ongoing infection basedon the higher heterophil counts in the colder seasons with respectto the warmer ones. In addition, the pattern is in line with thenotion that while acquired components are usually depressed bylower temperatures, some innate components might increase tooffset that reduction. Immune and health-state parameters weremostly independent of reproductive hormone levels, providinglittle support for a trade-off with reproduction. Overall, the observedseasonal pattern in immunity of broadnose sevengill sharkscould be related to changes in abiotic environmental condition,such as water temperature and photoperiod, although other factorssuch as availability of high-quality food may play a part.

Item Type: Article
Authors/Creators:Sueiro, MC and Awruch, CA and Irigoyen, AJ and Argemi, F and Palacios, MG
Keywords: ecoimmunology, ecophysiology, elasmobranchs, steroid hormones, seasonal changes, Patagonia
Journal or Publication Title: Physiological and Biochemical Zoology
Publisher: Univ Chicago Press
ISSN: 1522-2152
DOI / ID Number: 10.1086/700573
Copyright Information:

Copyright 2018 by the University of Chicago

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