March 9, 2004

Factors Affecting the Shoreline Distribution of Asiatic Clams, Corbicula fluminea (Müller), in the Hanford Reach,

Columbia River

Behr Turner, Battelle PNNLBrett Tiller, Battelle PNNL

Dr. Allan Scholz, EWU

March 9, 2004

Acknowledgements

• Battelle Staff:– Corey Duberstein– Dr. Janelle Downs– Dr. Bill Rickard– Ted Poston– Craig McKinstry– Bob Mueller– Ian Welch– Mickey Chamness– Donald Mendoza– Brad Fritz– Kate Deters

• PNNL OFP and Research Fellows:– Rochelle Shipley– Joe Zelinski– Kyle Larson– James Bernhard

• Eastern Washington University Staff:– Dr. Bruce Lang– Dr. Nancy Birch– Holly McLellan

• Conducted for the U.S. Department of Energy by Pacific Northwest National Laboratory under contract DE-AC06-76RLO 1830

• EWU Biology Department Graduate Research Grant

• EWU Alumni Graduate Research Grant

March 9, 2004

Introduction to Asiatic Clam

• Exotic– From South-central Asia– Believed to have been introduced in the 1920’s (McMahon 1983)

- Chinese immigrants- Voyage food source

– In 1938, this species was first identified in U.S. (Burch 1944)– No records of Asiatic clams in Hanford Reach of the Columbia River

during 1960’s and 1970’s

• 3-year life span• Established in Hanford Reach• Shoreline distribution affected by dewatering (Junk 1975;

McMahon 1979; Mouthon 2001; White 1979; White and White 1977)

March 9, 2004

Study Impetus

• Sentinel for monitoring Hanford-related metals and radionuclides in the environment– 47 years of plutonium production on the Hanford Site– Groundwater

- Current route of contaminant introduction to river

• River fluctuations complicate interpretation of sampling results and affect species distributions – River/Groundwater interaction affects contaminant uptake– Dewatering events affect condition and survival

• Need to describe shoreline distribution of A. clams along the Hanford Reach of the Columbia River

March 9, 2004

Hanford Reach of the Columbia R. and Study Area

March 9, 2004

Introduction

• Hanford Reach of the Columbia River– Last free-flowing stretch in

U.S. above Bonneville Dam– Great fluctuations in river

elevation- Due to hydraulic

operations at Priest Rapids Dam

- Flows greatly altered from natural state

March 9, 2004

Historic Versus Recall Flow Patterns

FCRPS 2001; Columbia River DART 2002

0

2000

4000

6000

8000

10000

12000

O N D J F M A M J J A S

Water Year

Flow

(m3 ·s-1

)

Historic

2001-2002

March 9, 2004

Site Conditions

• Study Area– 15-km stretch of the Hanford Reach– Characterized by swift currents and cobble substrate – Variable flows during sample seasons

0

2000

4000

6000

2002

Flow

(m3 •

s-1)

March 9, 2004

The Percentage of Time Shoreline Submerged on an Annual Basis

• Bathymetry transects– USGS and Grant County Public Utility District

• Hourly Priest Rapids Dam flow data– 1994-2001– 10 increments – a flow frequency distribution

• One-dimensional modular aquatic simulation system coupled with GIS– MASS1 (Richmond et al., 2000)– Generated GIS positions of known amounts of shoreline

submergence

March 9, 2004

Established Time Percentages of Shoreline Submergence and Corresponding Flows from 1994-2001 Priest Rapids Dam Hourly

Flows

1,35395.001,63090.001,83785.001,97080.002,13975.002,42570.002,72065.002,98360.003,23855.00

3,46350.00m3·s-1Percentage of time shoreline submerged

March 9, 2004

114

116

118

120

122

124

126

128

1300

100

200

300

400

500

600

700

800

Distance (m)

Elev

ation (m

abo

ve se

alev

el)

Bathymetry

50% Submerged

55% Submerged60% Submerged

65% Submerged

70% Submerged

75% Submerged

80% Submerged

85% Submerged90% Submerged

95% Submerged

Depiction of MASS1 Flow Levels and River Bathymetry

March 9, 2004

Distribution Data Collection

• Data collected August 30-September 29, 2002

• Two methods used to locate sample sites:– 1) Navigate to reference GIS position

- Trimble GeoExplorer® 3 handheld GPS mapping and GIS data collection/maintenance system

– 2) Average position of 50 percent submerge rate and transect bearing- Sample equidistant along transect to a depth of 1.5 m

• GIS point recorded at each location– Average of 100 positions logged at a rate of 1 position per

second - Precision less than 3 m

March 9, 2004

Distribution Data Collection

• Asiatic clam presence/absence:– Two 0.1-m2 plots randomly placed within 1-m2 plot

March 9, 2004

26 Shoreline Sites of Distribution Data Collection

March 9, 2004

Distribution Data Analysis

• Chi-Square Tests of Homogeneity– Based on presence and absence– Tested 11 shoreline submergence durations

• Pairwise comparisons– (Marascuilo and McSweeney 1977)

March 9, 2004

Asiatic Clam Distribution For Shoreline Submergence Intervals

Χ2>101.56, d.f.=10, p<0.05

0%

20%

40%

60%

80%

100%

<50

50-5

5

55-6

0

60-6

5

65-7

0

70-7

5

75-8

0

80-8

5

85-9

0

90-9

5

>95

Freq

uenc

y of

occ

urre

nce

March 9, 2004

Discussion

• Asiatic clam distribution– Intolerant to aerial exposure

– In other bodies of water, clams not found in dewatered shorelineareas (Junk 1975; McMahon 1979)- 50 % mortality after 4 days exposure (White and White 1977)- 98 % mortality after 12 days exposure (White 1979)

– Some shoreline areas experienced several consecutive days of dewatering at air temperatures exceeding 35 oC- A. clams were present in such areas

March 9, 2004

Discussion

• Asiatic clam distribution mechanism– Mucous thread creates buoyancy– Clams 14 mm in shell length could maintain buoyancy in

0.1 m·s-1 current (Prezant and Chalerwat 1984)– Deposited during flow fluctuations

March 9, 2004

Asiatic Clam Size Class Distribution between Three Functional Shoreline Zones in the Hanford Reach

0%20%40%60%80%

100%

Vascular vegetation Non-vegetated substrate Periphyton

(n=27) (n=1082) (n=986)

Perc

ent o

ccur

renc

e 5-11 mm

11-22 mm

>22 mm

Non-vegetated substrate Periphyton

Shoreline vascular vegetation

March 9, 2004

Conclusions

• Clams were consistently found in shoreline areas submerged > 90 percent of the time on an annual basis

• Dewatering is a environmental stressor

• Future aquatic biota exposure and impact studies on the Hanford Reach of the Columbia River (and other regulated river systems) should be performed at or below the low-water level