8/15/2012

1

Pearl Oysters (Pinctada) of

Midway Atoll (Northwestern

Hawaiian Islands)

Kristin McCully, Don Potts

Ecology and Evolutionary Biology Department

University of California, Santa Cruz

Western Society of Malacologists Meeting

June 2012

Pearl Oysters (Pinctada spp.)

• Economically important industry

• Important filter feeders

• Ecosystem indicators

– Heavy metals

– Nutrients

Gametes Larvae Recruits Juveniles Adults

Pearl Oysters of Hawaii

Pinctada radiata

• Small (up to 10 cm)

• Extensive beds in

Pearl Harbor, Oahu

• Die-off in mid-1800s due to

sedimentation

Pinctada margaritifera

• Much larger (up to 30 cm)

• Extensive beds at Pearl and

Hermes Atoll until 1920s

• USFWS and PMNM

interested in restoration

Photos courtesy of Bishop Museum in Walther (1997)

http://sanctuaries.noaa.gov/science/condition/pmnm/images/fig1_lg.jpg

Hawaiian Archipelago

Midway Atoll

(Wada and Tëmkin 2008,

Hwang et al. 2007,

Mavuti et al. 2005)

Sites of aquaculture of P. margaritifera

P. margaritifera

Black-lipped Pearl Oyster Pinctada margaritifera (Linnaeus 1756)

8/15/2012

2

Overall Questions

• What is the current spatial distribution of

pearl oysters (and other large bivalves)?

• How might managers restore the

population?

• What are their demographic rates?

– Recruitment

– Growth

– Survival

Midway Atoll

Distribution: Habitats

N

NW

Deep

S

SE

E

SWBased on: NOAA.

2003. Draft atlas of

the shallow-water

benthic habitats of the

NWHI.

Legend

Forereef

Backreef

Patch reef

Sand

Distribution: Survey SitesLegend

2009 2011 Habitat

Backreef

Forereef

Patch reef

Sand

n = 108 surveys

Baggy pen shell

Streptopinna saccata

Cliff oyster Spondylus violacescens

Black-lipped pearl oyster

Pinctada margaritifera

Jewel oyster

Chama iostoma

Distribution: P. margaritifera

500 m

8/15/2012

3

0

1

2

3

4

5

6

7

8

Spondylus Chama Streptopinna

Ave

rage

Nu

mb

er

of

Biv

alv

es

pe

r 1

00

sq

m (

±S

E)

Species

Fore Back Patch Sand

Distribution: Other Bivalves

Habitat:

Restoration?

Spat

collector

Recruitment: Methods Predation on P. margaritifera

• Highest risk of mortality as juveniles

• Escape size 80-100 mm (Crossland 1957 in Gervis and Sims 1992)

• Potential predators (Gervis and Sims 1992)

– Fish

– Octopus

– Predatory gastropods

– Sea stars

– Crabs

Juvenile Growth, Survival, & Predation

Site: WB

No Mesh Large Mesh

X 4 tiles X 4 tiles

X 3

juveniles

X 3

juveniles

PP

WB

Site: PP

No Mesh Large Mesh

X 4 tiles X 4 tiles

X 3

juveniles

X 3

juveniles

Juvenile Survival & Predation: Results

0%

10%

20%

30%

40%

50%

60%

70%

Open Closed

Pe

rce

nt

Su

rviv

al fo

r 3

8 d

ay

s (±

SE

)

Cage Status

8/15/2012

4

Adult Growth and Survival

500 m

Molecular Species Identification: Methods

• Very hard to identify Pinctada

species morphologically

(particularly juveniles)

• Collected about 100 juveniles at

Midway

• Variety of coloration, location,

size, dates collected, methods

of preservation

• Marker: ITS1 between nuclear

rDNA genes (Yu and Chu 2006

Biochemical Systematics and Ecology)

18S 5.8SITS1

Pinctada Phylogeny

Cunha et al. (2011) Marine Biotech

Photo courtesy of Bishop Museum, Honolulu in

Walther 1997

Phylogeny

• Midway samples

– Definitely not P.

margaritifera

– Likely P.

maculata

• Working on

sequencing

mitochondrial

cytochrome

oxidase I (cox1)

marker

Pteria penguin

P. albina1

P. albina2

P. chemnitzi1

P. chemnitzi2

P. fucata1

P.f. martensi1

P.f. martensi2

P. fucata2

P. fucata3

P. imbricata

P. martensi

0.05 substitutions/site

99/99/97/100

85/82/75/73

66/66/60/98

ML/MP/NJ/BPP

P. margaritifera2

P. maxima

P. margaritifera1

P. margaritifera3

P. margaritifera4

P. maculata1

P. maculata2

P. maculata3

18 Midway samples

P. nigra

Model: Goals

• To determine most important data to collect

in the Hawaiian archipelago

• To establish priority life stages and

demographic processes for managers

• To estimate probable impacts of

management options, including restoration

Model: Life Cycle Diagram

Gametes Larvae Recruits Juveniles Adults

8/15/2012

5

Male

Large

Adults

Model: Life Cycle Diagram

Juveniles

Female

Large

Adults

Male

Small

Adults

Time Step:

1 year

Female

Small

Adults

Model: Transition Matrix

FROM

1 2m 2f 3m 3f

TO

1 s1(1-g1) 0 f2s0 0 f3s0

2m s1g1(1-sx2) s2(1-g2)(1-sx2) 0 0 0

2f s1g1sx2 s2(1-g2)sx2 s2(1-g2) 0 0

3m 0 s2g2(1-sx3) 0 s3(1-sx3) 0

3f 0 s2g2sx3 s2g2 s3sx3 s3

Model: Vital Rates

Description VR

Probability of survival

s0

s1

s2

s3

Probability of growth transitiong1

g2

Fecundity of femalesf2

f3

Probability of becoming femalesx2

sx3

Conclusions and Next Steps

• P. margaritifera is very rare at Midway, but is

most common on patch reefs in central lagoon

• Other bivalves are more common on forereef

• Very difficult to restore P. margaritifera, given

biology and regulatory climate

• Next steps:

– Confirm species identity of recruits

– Use molecular techniques to check species

identity of pearl oysters in Main Hawaiian Islands

– Further develop and analyze mathematical model

Acknowledgments: Funding

• Mitsubishi Corporation Global Coral Reef

Conservation Program

• U.S. Fish and Wildlife Service

• Midway Atoll National Wildlife Refuge

• Friends of Long Marine Lab

• UCSC Center for the Dynamics and Evolution of the

Land-Sea Interface (CDELSI)

• DoD National Defense Science and Engineering

(NDSEG) Fellowship

• UCSC NSF GK-12 grant SCWIBLES

Acknowledgments: People

• Advisor: Don Potts

• Proposal committee:

Laurel Fox

Tim Tinker

Maria Haws (UHawaii)

• Statistics help: Pete Raimondi

• Labmates:

Wendy Cover, Anne Warner,

Helen O’Brien, Rachel Fabian

• Lab volunteer: Ryan Harry

30

8/15/2012

6

Acknowledgments: Midway Team

• Field assistants:

– Kate Schoenrock

– Jamie Barlow

• Field volunteers:

– Jessica Lee

– Mitsubishi

volunteers

(2008-11)

• John Klavitter &

Matt Brown

(USFWS) 31