scholarly journals Reciprocal abundance shifts of the intertidal sea stars, Evasterias troschelii and Pisaster ochraceus , following sea star wasting disease

2019 ◽  
Vol 286 (1901) ◽  
pp. 20182766 ◽  
Author(s):  
Sharon W. C. Kay ◽  
Alyssa-Lois M. Gehman ◽  
Christopher D. G. Harley
Keyword(s):  
Indirect Effects ◽  
Interference Competition ◽  
Disease Outbreaks ◽  
Ecological Communities ◽  
Population Declines ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Field Surveys ◽  
Pisaster Ochraceus

Disease emergence occurs within the context of ecological communities, and disease driven declines in host populations can lead to complex direct and indirect ecological effects. Varying effects of a single disease among multiple susceptible hosts could benefit relatively resistant species. Beginning in 2013, an outbreak of sea star wasting disease (SSWD) led to population declines of many sea star species along the west coast of North America. Through field surveys and laboratory experiments, we investigated how and why the relative abundances of two co-occurring sea star species, Evasterias troschelii and Pisaster ochraceus , shifted during the ongoing wasting epidemic in Burrard Inlet, British Columbia, Canada. We hypothesized that Evasterias is competitively inferior to Pisaster but more resistant to SSWD. Thus, we predicted that SSWD-induced declines of Pisaster could mitigate the negative effects of SSWD on Evasterias , as the latter would experience competitive release. We document shifts in sea star abundance from 2008–2017: Pisaster abundance and mean size declined during the outbreak, while Evasterias abundance increased from relatively rare to numerically dominant within the intertidal. When exposed to symptomatic sea stars, Pisaster and Evasterias both showed signs of SSWD, but transmission and susceptibility was lower in Evasterias. Despite diet overlap documented in our field surveys, Evasterias was not outcompeted by Pisaster in laboratory trails conducted with the relatively small Pisaster available after the outbreak. Interference competition with larger Pisaster , or prey exploitation by Pisaster during the summer when Evasterias is primarily subtidal, may explain the rarity of Evasterias prior to Pisaster declines. Our results suggest that indirect effects mediated by competition can mask some of the direct effects of disease outbreaks, and the combination of direct and indirect effects will determine the restructuring of a community after disturbance.

scholarly journals What doesn’t kill them makes them stronger: an association between elongation factor 1-αoverdominance in the sea starPisaster ochraceusand “sea star wasting disease”

PeerJ ◽  
2016 ◽  
Vol 4 ◽  
pp. e1876 ◽  
Author(s):  
John P. Wares ◽  
Lauren M. Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive mortality event has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease event, known as ‘sea star wasting disease’ (SSWD), is linked to viral infection. In one affected sea star (Pisaster ochraceus), previous work had identified that the elongation factor 1-αlocus (EF1A) harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations ofP. ochraceusto identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased occurrence of SSWD in individuals that are heterozygous at this locus. These results suggest further studies are warranted to understand the functional relationship between diversity at EF1A and survival inP. ochraceus.

scholarly journals What doesn’t kill them makes them stronger: An association between elongation factor 1-α overdominance in the sea star Pisaster ochraceus and "sea star wasting disease”

2016 ◽  
Author(s):  
John P. Wares ◽  
Lauren M Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive plague has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease, known as 'sea star wasting disease' (SSWD), is thought to be caused by viral infection. In the affected sea star Pisaster ochraceus, previous work had identified that the elongation factor 1-α (EF1A) locus harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations of P. ochraceus to identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased infection or mortality rates in individuals that are heterozygous at this locus. These results suggest further studies to understand the functional relationship between diversity at EF1A and survival in P. ochraceus.

scholarly journals What doesn’t kill them makes them stronger: An association between elongation factor 1-α overdominance in the sea star Pisaster ochraceus and "sea star wasting disease”

2016 ◽  
Author(s):  
John P. Wares ◽  
Lauren M Schiebelhut
Keyword(s):  
Pacific Coast ◽  
Functional Relationship ◽  
Elongation Factor ◽  
Sea Star ◽  
Sea Stars ◽  
Wasting Disease ◽  
Pisaster Ochraceus ◽  
The Pacific ◽  
The Relationship ◽  
Elongation Factor 1

In recent years, a massive plague has killed millions of sea stars, of many different species, along the Pacific coast of North America. This disease, known as 'sea star wasting disease' (SSWD), is thought to be caused by viral infection. In the affected sea star Pisaster ochraceus, previous work had identified that the elongation factor 1-α (EF1A) locus harbored an intronic insertion allele that is lethal when homozygous yet appears to be maintained at moderate frequency in populations through increased fitness for heterozygotes. The environmental conditions supporting this increased fitness are unknown, but overdominance is often associated with disease. Here, we evaluate populations of P. ochraceus to identify the relationship between SSWD and EF1A genotype. Our data suggest that there may be significantly decreased infection or mortality rates in individuals that are heterozygous at this locus. These results suggest further studies to understand the functional relationship between diversity at EF1A and survival in P. ochraceus.

scholarly journals Virome Variation during Sea Star Wasting Disease Progression in Pisaster ochraceus (Asteroidea, Echinodermata)

Viruses ◽  
2020 ◽  
Vol 12 (11) ◽  
pp. 1332
Author(s):  
Ian Hewson ◽  
Citlalli A. Aquino ◽  
Christopher M. DeRito
Keyword(s):  
Viral Genome ◽  
Marine Invertebrates ◽  
Scar Tissue ◽  
Sea Star ◽  
Wasting Disease ◽  
Viral Genomes ◽  
Normal Tissues ◽  
Pisaster Ochraceus ◽  
Affected Tissue ◽  
External Stimuli

Sea star wasting disease (SSWD) is a condition that has affected asteroids for over 120 years, yet mechanistic understanding of this wasting etiology remains elusive. We investigated temporal virome variation in two Pisaster ochraceus specimens that wasted in the absence of external stimuli and two specimens that did not experience SSWD for the duration of our study, and compared viromes of wasting lesion margin tissues to both artificial scar margins and grossly normal tissues over time. Global assembly of all SSWD-affected tissue libraries resulted in 24 viral genome fragments represented in >1 library. Genome fragments mostly matched densoviruses and picornaviruses with fewer matching nodaviruses, and a sobemovirus. Picornavirus-like and densovirus-like genome fragments were most similar to viral genomes recovered in metagenomic study of other marine invertebrates. Read recruitment revealed only two picornavirus-like genome fragments that recruited from only SSWD-affected specimens, but neither was unique to wasting lesions. Wasting lesion margin reads recruited to a greater number of viral genotypes (i.e., richness) than did either scar tissue and grossly normal tissue reads. Taken together, these data suggest that no single viral genome fragment was associated with SSWD. Rather, wasting lesion margins may generally support viral proliferation.

scholarly journals Disease epidemic and a marine heat wave are associated with the continental-scale collapse of a pivotal predator (Pycnopodia helianthoides)

2019 ◽  
Vol 5 (1) ◽  
pp. eaau7042 ◽  
Author(s):  
C. D. Harvell ◽  
D. Montecino-Latorre ◽  
J. M. Caldwell ◽  
J. M. Burt ◽  
K. Bosley ◽  
...  
Keyword(s):  
Disease Outbreaks ◽  
Sea Surface ◽  
Sea Star ◽  
Wasting Disease ◽  
Infectious Disease Outbreaks ◽  
Continental Scale ◽  
Endemic Birds ◽  
Ecosystem Level ◽  
The Common ◽  
Trawl Surveys

Multihost infectious disease outbreaks have endangered wildlife, causing extinction of frogs and endemic birds, and widespread declines of bats, corals, and abalone. Since 2013, a sea star wasting disease has affected >20 sea star species from Mexico to Alaska. The common, predatory sunflower star (Pycnopodia helianthoides), shown to be highly susceptible to sea star wasting disease, has been extirpated across most of its range. Diver surveys conducted in shallow nearshore waters (n= 10,956; 2006–2017) from California to Alaska and deep offshore (55 to 1280 m) trawl surveys from California to Washington (n= 8968; 2004–2016) reveal 80 to 100% declines across a ~3000-km range. Furthermore, timing of peak declines in nearshore waters coincided with anomalously warm sea surface temperatures. The rapid, widespread decline of this pivotal subtidal predator threatens its persistence and may have large ecosystem-level consequences.

scholarly journals Competitors as accomplices: seaweed competitors hide corals from predatory sea stars

2015 ◽  
Vol 282 (1814) ◽  
pp. 20150714 ◽  
Author(s):  
Cody S. Clements ◽  
Mark E. Hay
Keyword(s):  
Field Experiments ◽  
Coral Cover ◽  
Ecological Communities ◽  
Protective Effects ◽  
Sea Star ◽  
Sea Stars ◽  
Macroalgal Blooms ◽  
Feeding Experiments ◽  
High Preference ◽  
And Function

Indirect biotic effects arising from multispecies interactions can alter the structure and function of ecological communities—often in surprising ways that can vary in direction and magnitude. On Pacific coral reefs, predation by the crown-of-thorns sea star, Acanthaster planci , is associated with broad-scale losses of coral cover and increases of macroalgal cover. Macroalgal blooms increase coral–macroalgal competition and can generate further coral decline. However, using a combination of manipulative field experiments and observations, we demonstrate that macroalgae, such as Sargassum polycystum , produce associational refuges for corals and dramatically reduce their consumption by Acanthaster . Thus, as Acanthaster densities increase, macroalgae can become coral mutualists, despite being competitors that significantly suppress coral growth. Field feeding experiments revealed that the protective effects of macroalgae were strong enough to cause Acanthaster to consume low-preference corals instead of high-preference corals surrounded by macroalgae. This highlights the context-dependent nature of coral–algal interactions when consumers are common. Macroalgal creation of associational refuges from Acanthaster predation may have important implications for the structure, function and resilience of reef communities subject to an increasing number of biotic disturbances.

scholarly journals Genetic variation associated with lower susceptibility to sea star wasting syndrome in the keystone species, Pisaster ochraceus

2021 ◽  
Author(s):  
Andrea Burton ◽  
Sarah Gravem ◽  
Felipe Barreto
Keyword(s):  
Genetic Variation ◽  
Keystone Species ◽  
Disease Status ◽  
Sea Star ◽  
Sea Stars ◽  
Protein Coding ◽  
Functional Studies ◽  
Pisaster Ochraceus ◽  
Wasting Syndrome ◽  
Asymptomatic Individuals

The keystone species, Pisaster ochraceus, suffered mass mortalities along the northeast Pacific Ocean from Sea Star Wasting Syndrome (SSWS) outbreaks in 2013-2016. Causation of SSWS is still debated, leading to concerns as to whether outbreaks will continue to impact this species. Considering the apparent link between ocean temperature and SSWS, the future of this species and intertidal communities remains uncertain. We surveyed populations of sea stars along the Oregon coast in 2016, two years after the epidemic began. Cohabitation of asymptomatic and symptomatic individuals allowed us to ask whether lower susceptibility in asymptomatic individuals differed genetically. We performed restriction site-associated DNA sequencing (2bRAD-seq) to genotype thousands of single nucleotide polymorphism (SNP) loci. By comparing allele frequencies between symptomatic and asymptomatic individuals, we detected three loci that may be under selection. A multivariate analysis showed a clear separation between groups based on disease status in two of the three geographic regions, along with several regions across the genome having small statistical contributions to this separation. A draft annotation of protein-coding regions allowed us to identify 120 predicted genes that are linked to these markers and are putatively associated with lower susceptibility. Our results suggest that some variation in disease severity can be attributed to genetic variation. However, differences in phenotype have a highly polygenic nature with no single or few genomic regions having strong predictive effects. The genes associated with these regions may form the basis for functional studies aiming to understand disease progression in infected individuals.

scholarly journals Virome Temporal Variation During Sea Star Wasting Disease Progression in Pisaster ochraceus (Asteroidea, Echinodermata)

2020 ◽  
Author(s):  
Ian Hewson ◽  
Citlalli A. Aquino ◽  
Christopher M. DeRito
Keyword(s):  
Viral Genome ◽  
Marine Invertebrates ◽  
Scar Tissue ◽  
Sea Star ◽  
Wasting Disease ◽  
Viral Genomes ◽  
Normal Tissues ◽  
Pisaster Ochraceus ◽  
Affected Tissue ◽  
External Stimuli

Sea star wasting disease (SSWD) is a condition that has affected asteroids for over 120 years, yet mechanistic understanding of wasting etiology remains elusive. We investigated temporal virome variation in two Pisaster ochraceus specimens that wasted in the absence of external stimuli and two specimens that did not experience SSWD for the duration of our study, and compared viromes of wasting lesion margin tissues to both artificial scar margins and grossly normal tissues over time. Global assembly of all SSWD-affected tissue libraries resulted in 45 viral genome fragments represented in >1 library. Genome fragments mostly matched densoviruses and picornaviruses with fewer matching nodaviruses, narnaviruses and sobemoviruses. Picornavirus-like and densovirus-like genome fragments were most similar to viral genomes recovered in metagenomic study of other marine invertebrates. Read recruitment revealed only 2 picornavirus-like genome fragments that recruited from only SSWD-affected specimens, but neither was unique to wasting lesions. Wasting lesion margin reads recruited to a greater number of viral genotypes (i.e. richness) than did either scar tissue and grossly normal tissue reads. Taken together, these data suggest that no single viral genome fragment was associated with SSWD. Rather, wasting lesion margins may generally support viral proliferation.

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