The Distribution and Abundance of the Non-native Eelgrass Zostera japonica in Oregon Estuaries

Chana Dudoit

Mentor: Dr. Sylvia Yamada

Zoology Dept.

The Importance of Eelgrass Meadows in an Estuary

Nursery for juvenile fish

Foraging habitat

Commercial industries Nutrient cycling

prey

Seed oyster industry

Used as packaging material

Washington State

1950’s

Waves ~plants are carried in the currents

Birds ~seeds are eaten

Ships~plants were used as packaging material

People~accidental or purposefully moved~attached to boat motors

Low Tide

•Comparative analysis of Z. japonica expansion

•Effect on habitat composition

•Change in species composition and abundance

Z. Japonica Netarts Bay Low Tide

Species Composition

Stabilize substrate

Habitat degradation

Netarts Bay

South Slough National Estuarine Research Reserve (SSNERR)

Bandon Marsh National Wildlife Refuge

Penetrometer: measures the density of a substrate

Percent Cover of Z. japonica in Netarts Bay 2005

50-74%

25-49%

1-24%

>75%

Small isolated patches

1984 2004 2005

50-74%

25-49%

1-24%

>75%

Small isolated patches

Percent Cover of Z. japonica in

South Slough National Estuarine Research Reserve

50-74%

25-49%

1-24%

>75%

Small isolated patches

Percent Cover of Z. japonica in

Bandon Marsh National Wildlife Refuge, 2005

Developing technologies

Aerial photographic surveys using

•true color (TC) film

•false-color near-infrared (color infrared, CIR) film

Dr. Sylvia Yamada, Zoology Dept. OSU

Dr. Samuel Chan, Oregon Sea Grant, OSU

Dr. David Young, EPA Newport

Derek Sowers, SSNERR

Scott Growth, DFW

Chelsea Dudoit, volunteer