Type locality, 1st Records: WA/Willapa Bay (1988, Dumbauld et al. 2011; Chapman et al. 2012)
WA/South Bay, Grays Harbor (2006, Chapman et al. 2012, 46o 53’ 36.41” N; 124o 03’ 40.15” W); WA/Willapa Bay (1988, Dumbauld et al. 2011; Chapman et al. 2012); Goose Point/WA/Willapa Bay (1/19/2009, Williams and An 2009; Dumbauld et al. 2011; Chapman et al. 2012); WA/Willapa Bay (Floyd and Chapman 2005; Chapman et al. 201); OR/Tillamook Bay (Floyd and Chapman 2005; Chapman et al. 2012); OR/Siletz Bay (Floyd and Chapman 2005); OR/Netarts Bay (2006, Chapman et al. 2012); Mudflats, Lincoln County/OR/Idaho Inlet, Yaquina Bay (Type locality, 1999, Markham 2004, paratypes collected 6/23/2000; Chapman et al. 2012); Riverbend/OR/Yaquina Bay (1999, Markham 2004, Chapman et al. 2012); OR/Alsea Bay (Floyd and Chapman 2005); OR/Coos Bay CA/Morro Bay (1992, Chapman et al. 2012); Charleston/OR/Coos Bay (5/18/2000, Williams and An 2009, parasitic on Upogebia pugettensis; Chapman et al. 2012); low intertidal fringe along the main channel southeast of Bird Island/CA/Humboldt Bay (2007, Chapman et al. 2012, 40o 49’ 33.86” N; 124o 09’ 26.00” W, one parasitized Upogebiawas collected).
|Orthione griffenis, a bopyrid isopod, inhabits the gill chamber of the mud shrimp Upogebia pugettensis, and sucks its blood, greatly reducing the shrimp's reproductive potential (Floyd and Chapman 2005; Smith et al. 2008; Griffen 2009). In Yaquina Bay, prevalence of these parasites was high 57% for males, 80% for females (Smith et al. 2008). The metabolic costs of parasitism are likely to reduce the abundance of this species in the upper intertidal parts of its range, where feeding time is limited, while animals in the lower intertidal have more food, but also more exposure to the planktonic stages of the parasites (Griffen 2009). A decline in abundance of U. pugettensis has been observed throughout its range, coinciding with the arrival of the parasite (Griffen 2009), but the role of the parasite in mortality and reproduction of the shrimp is not clear (Smith et al. 2008; Dumbauld et al. 2011). Griffen (2009) modelled the shrimps' metabolism and reproduction throughout the tidal range, and found evidence that shrimps would be adversely affected both at the upper and lower limits of their tidal range. The decline of Upogebia pugettensis in Willapa Bay showed patterns consistent with a failure of recruitment, due to reproductive castration of adults. Shrimp abundance decreased as the isopod prevalence increased, although isopod parasitism did not affect adult mortality. However, infected shrimp failed to reproduce (Dumbauld et al. 2011). Populations of Upogebia pugettensis in Alsea Bay have been declining, from 1992 to 2011, due to parasitism and castration by Orthione griffenis (Chapman and Carter 2014).|
|Ecological Impact||Trophic Cascade|
|A decline in abundance of Upogebia pugettensis has been observed throughout its range, coinciding with the arrival of the parasite (Griffen 2009). The mud shrimp is a major player in the foodweb of northeast Pacific estuaries, as a suspension-feeder and intertidal prey item for birds and fishes, and is also an important ecosystem engineer as a burrower (Smith et al. 2008; Griffen 2009).|
|Upogebia pugettensis is widely used as fishbait in the Pacific Northwest, so that its decline could affect recreational fishing (Floyd and Chapman 2005). Commercial harvests from major Oregon bays declined from 1988 to 2011 (Chapman et al. 2014). On the other hand, this mud shrimp is regarded as a pest in oysterbeds, and is controlled with the pesticide Carbaryll so that its decline might have benefits for oyster fisheries (Smith et al. 2008).|