No evidence that the introduced parasite Orthione griffenis markham, 2004 causes sex change or differential mortality in the native mud shrimp, Upogebia pugettensis (Dana, 1852)

Asson, Danielle, Chapman, John W., and Dumbauld, Brett R. (2017) No evidence that the introduced parasite Orthione griffenis markham, 2004 causes sex change or differential mortality in the native mud shrimp, Upogebia pugettensis (Dana, 1852). Aquatic Invasions, 12 (2). pp. 213-224.

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Dramatic, rapid, population declines of the native North American burrowing shrimp Upogebia pugettensis (Dana, 1852) are associated with intense infestations by the introduced Asian bopyrid isopod parasite, Orthione griffenis Markham, 2004. However, expected host weight losses with increasing parasite weights do not occur, even among apparently castrated females. The prevailing assumption that energetic losses cause host castration have thus remained open to question, and the mechanism(s) resulting in castration and consequent population declines of U. pugettensis have remained unclear. Proposed alternative explanations for these declines, which have been based on a dramatically greater prevalence of O. griffenis among U. pugettensis females, include parasite induced sex change, increased male mortality, and differential tidal exposure of sexes to settling O. griffenis larvae. We examined 508 O. griffenis infestations from 2,014 shrimp collected from 26 stations in 5 Oregon estuaries to test these alternative hypotheses. We expected greater infestation frequencies among females than among males and a close association of O. griffenis infestations with intersex shrimp in the overall population if feminization occurs. We also expected covariation in sex ratio with tide exposure if O. griffenis settlement is sex linked. Instead, we found an overall 1:1.07 sex ratio, a lack of association of intersex U. pugettensis with O. griffenis infestations, and an unchanging sex ratio with tidal exposure, precluding parasite induced sex change, male mortality, or tidal immersion effects on infestations. The most likely mechanism driving U. pugettensis declines thus remains castration due to host energetic losses. This energetic interaction is likely to be resolved quantitatively through controlled experiments and increasingly detailed field surveys over time.

Item ID: 54103
Item Type: Article (Research - C1)
ISSN: 1818-5487
Keywords: Bopyrid isopod; castration; co-evolution; energetic losses; feminization; Gebiid shrimp; mudflat
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Aquatic Invasions is an Open Access journal which means that all content is freely available without charge to the user or his/her institution. Users are allowed to read, download, copy, distribute, print, search, or link to the full texts of the articles in this journal without asking prior permission from the publisher or the author. This is in accordance with the BOAI definition of Open Access.

Funders: Oregon State University Ocean Sciences Research Experiences for Undergraduates REU, US Department of Defense ASSURE program, National Science Foundation (NSF) Research Experiences for Undergraduates (REU)
Projects and Grants: NSF OCE-1004947
Date Deposited: 15 Jun 2018 05:39
FoR Codes: 41 ENVIRONMENTAL SCIENCES > 4102 Ecological applications > 410202 Biosecurity science and invasive species ecology @ 30%
31 BIOLOGICAL SCIENCES > 3103 Ecology > 310305 Marine and estuarine ecology (incl. marine ichthyology) @ 40%
31 BIOLOGICAL SCIENCES > 3109 Zoology > 310913 Invertebrate biology @ 30%
SEO Codes: 96 ENVIRONMENT > 9604 Control of Pests, Diseases and Exotic Species > 960407 Control of Pests, Diseases and Exotic Species in Marine Environments @ 50%
96 ENVIRONMENT > 9608 Flora, Fauna and Biodiversity > 960808 Marine Flora, Fauna and Biodiversity @ 50%
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