Effects of temperature, season and locality on wasting disease in the keystone predatory sea star Pisaster ochraceus

Abstract

This study investigates wasting disease in the northeast Pacific keystone predatory sea star Pisaster ochraceus on the outer west coast of Vancouver Island (British Columbia, Canada). To quantify the effects of temperature, season and locality on the vulnerability of P. ochraceus to wasting disease, we conducted surveys and experiments in early and late summer. To test the prediction that a small increase in temperature would result in heightened infection intensities, we housed sea stars at different temperatures in the laboratory and caged sea stars subtidally at 2 depths. Prevalence and infection intensity were always higher in warm temperature treatments and did not differ between the sexes or with increasing size. Disease effects also varied with season and locality. Specimens held in aquaria displayed significantly higher disease prevalence and infection intensity in June versus August. Furthermore, sea stars from a sheltered inlet showed markedly higher prevalence of the disease in late summer, while wave-exposed sites had consistently low disease prevalence. Seasonal changes in reproductive potential, host condition and/or physiological acclimation, as well as differences in environmental regime among localities, may impact the dynamics of wasting disease. These results demonstrate that small increases in temperature could drive mass mortalities of Pisaster due to wasting disease, with vulnerability possibly reaching a peak in spring and in populations from sheltered localities. This is the most northern report of wasting disease in the class Asteroidea on the west coast of North America. KEY WORDS: Global warming · Temperature · Wasting disease · Pisaster ochraceus · Echinoderm Resale or republication not permitted without written consent of the publisherDis Aquat Org 86: [245][246][247][248][249][250][251] 2009 One category of disease, referred to as 'wasting disease', has the potential to devastate echinoderm populations because it can rapidly cause death and has been documented in many species that play key community roles (e.g. 10 sea star, 3 sea urchin, 2 brittlestar and 1 sea cucumber species from the northeast Pacific, Eckert et al. 1999; 1 sea star species from the Mediterranean, Staehli et al. 2008). For example, Dungan et al. (1982) attributed mass mortality and large-scale population declines in the sun star Heliaster kubiniji to wasting disease. The etiologic agent responsible for wasting disease is unknown and may vary among species and localities. Attempts to link a bacterium to the disease using molecular tools have not yet been successful (e.g. Staehli et al. 2008); nevertheless, wasting disease progresses in a predictable fashion. Initially, white coloured lesions appear and rapidly grow, followed by loss of turgor, body disintegration, decay, and death (Dungan et al. 1982, Eckert et al. 1999, Staehli et al. 2008. The incidence and progression of wasting disease appear to be highly temperature sensitive. For instance, widespread mortality of several sea stars, including t...

Investigating the Complex Association Between Viral Ecology, Environment, and Northeast Pacific Sea Star Wasting

“…Keywords: sea star wasting, Asteroidea, densovirus, RNA virus, pathogen INTRODUCTION Sea star wasting disease (SSWD) describes a suite of common atypical gross morphological signs (loss of turgor, appearance of lesions, limb autotomy, and loss of body wall integrity) affecting members of the class Asteroidea, which in some cases result in animal mortality (Eckert et al, 1999;Staehli et al, 2008;Bates et al, 2009). Diseases have been reported more widely in Echinoidea (Jangoux, 1987), including during the catastrophic losses of the tropical urchin Diadema antillarum in the early 1980s (Lessios et al, 1984;Lessios, 1988Lessios, , 1995Lessios, , 2005.…”

“…Diseases have been reported more widely in Echinoidea (Jangoux, 1987), including during the catastrophic losses of the tropical urchin Diadema antillarum in the early 1980s (Lessios et al, 1984;Lessios, 1988Lessios, , 1995Lessios, , 2005. SSWD has been reported in northeast Pacific populations since at least 2008 (Bates et al, 2009;Gravem and Morgan, 2017), and in southern California since the late 1970s (Dungan et al, 1982). Beginning in mid-to late-2013, SSWD was observed in the northeast Pacific across a wide taxonomic diversity (>20 species) of asteroids.…”

Complementary approaches to diagnosing marine diseases: a union of the modern and the classic

“…Beginning in June 2013, a disease known as 'sea star wasting disease' (SSWD) caused mass mortality in 20 sea star species [29]. The number of host species affected, geographical range, time scale and associated death is unprecedented [30][31][32]. Cascading largescale ecological impacts may occur as a consequence of this event.…”

Densovirus associated with sea-star wasting disease and mass mortality

“…SSWD has been used to collectively describe die-offs of sea stars in the Northeast Pacific since at least 1979; however, this SSWD event differs from other asteroid mass mortalities (1)(2)(3)(4)(5) due to its broad geographic extent (from Baja California, Mexico to Southern Alaska; pacificrockyintertidal.org) and many (n = 20) species affected, representing several major lineages of Asteroidea ( Fig. 1, Table S1, and SI Text).…”

“…Scientific hypotheses given for other asteroid mortality events include storms (6-11), temperature anomalies (1,3,12), starvation (13), and infection by unidentified pathogens (5). For instance, pathogens in the bacterial genus Vibrio (12,14,15) and an unidentified eukaryotic parasite (4) were seen in die-offs of the tropical asteroid Acanthaster planci and the Mediterranean asteroid Astropecten jonstoni.…”