Sea Star Wasting Disease Updates

Monica Moritsch, PhDSanctuary Advisory Council Meeting

December 2018

• Symptoms• Twisted arms, deflated

appearance• Tissue decay, lesions• Arm loss, often death

• Worst in 2013 – 2014• Still present at low levels (< 20%)• Most severely impacted: • Pisaster ochraceus• Pycnopodia helianthoides

Is Sea Star Wasting Disease (SSWD) Still Around?

Kit Harma

• Probably the North American Pacific coast• Happened before on regional

scales• Often coincided with El Niño or

warm water• Was present at very low levels

for decades

Where did SSWD come from?

Angela Johnson

• Unknown cause and mechanism of spread• Virus(es) involved?• Environmentally driven?• Stress-driven?

• Lab trials of sea star microbiome • No consistent pathogen found to

cause lesions

Do we know what causes it? Pathogen search

Melissa Miner

Long Marine Lab

Do we know what causes it? Environmental factors

Environmental factors relevant for whole coast

↑ Proximity to nearest infected site ↑ Afternoon low tide exposure

LauraAnderson

• No warm water pattern– Different from prior

outbreaks

• Low tide duration– ↑ virulence? – ↑ susceptibility?

• Correlation, NOT causation

No clear relationship with warm water

• Not sure if immune or just recovered• Possible resistance genes in Pisaster

under investigation (UC Merced)

Are the surviving stars immune?

G. Contolini

• Relatively high recruitment in Sanctuary• Shifted size structure to small individuals• Biomass still low → low predation pressure

Recovery in progress for Pisaster, but not normal yetMelissa

Miner

201520162017

Abundance

prop

orti

on lo

ng-t

erm

bio

mas

s0

0

.2

0.4

0.6

0

.8

1.0

1

.2

1.4

prop

orti

on lo

ng-t

erm

num

ber

0

1

2

3

4

AK Salish Sea WA Olympic OR CA North N. Central CA Central Channel Isl. CA South

AK Salish Sea WA Olympic OR CA North N. Central CA Central Channel Isl. CA South

• Most regions below long-term average abundance

• Further below long-term average biomass (predation pressure)

NA

NA NA NA

Biomass

Comparison to long-term

Moritsch and Raimondi 2018. Ecology and Evolution.

Pisaster ochraceus sizes, Long Marine Lab, Santa Cruz

Sampling year + season

Arm

leng

th (m

m)

Number of individuals

Pisaster ochraceus sizes, Long Marine Lab, Santa Cruz

Sampling year + season

Arm

leng

th (m

m)

0

10

2

0

30

4

0

50

60

70

8

0

Pisaster ochraceus sizes, Hopkins Marine Station, Pacific Grove

Sampling year + season

Arm

leng

th (m

m)

Number of individuals

Pisaster ochraceus sizes, Point Sierra Nevada, San Luis Obispo County

Sampling year + season

Arm

leng

th (m

m)

Number of individuals

Sunflower stars → urchins (mostly purple) → kelp

Steve Lonhart Josh Smith

Steve Lonhart

Pycnopodia not recovering

Intertidal community effects of low Pisaster

Hakai Magazine

StillwaterCove

Spring 2014

StillwaterCove

Spring 2015

PISCO

PISCO

Asilomar,April 2014

Asilomar,April 2015 John

Pearse

Asilomar,April 2014

Asilomar,March 2018 John

Pearse

Perspective on mussel bed change

seastarwasting.orgmmoritsc@ucsc.edu

Questions?

Davenport Landing, April 2014

Davenport Landing, May 2017

CA Dept. of Fish and Wildlife

Kelp loss and urchin barrens

• ↓ Distance from nearest infected site

Results: Whole coast patterns –neighbor sites and low tide duration

Closer Farther

• ↑ Afternoon low tide exposure

Results: Whole coast patterns –neighbor sites and low tide duration

Less time More time

Prop

ortio

n of

indi

vidu

als

Recovering post-SSWS size distribution 2015

2016

2017

Arm length (mm)

Prop

ortio

n of

in

divi

dual

s

Pre-SSWS size distribution

Terrace Point, CASkewed size structures

Moritsch and Raimondi 2018. Ecology and Evolution.