Eastern Oyster Population in the Lower Choptank River

By Matthew Cuber, Rodney Hosler, Angela Kuzma

7/1/10

Research Question

• To what extent does turbidity caused by storm surge affect the Eastern Oyster populations, in the Lower Choptank River?

The Choptank River

• A major tributary of the Chesapeake Bay

• Watershed is 1,004 sq mi• 68 mi long• Longest river on Eastern shore

The Choptank River Species

• The river is home to an estimated:– 3.9 million fish – Including 30 different species– 11 species of reptiles/amphibians– 3 freshwater mussel species– AND THE EASTERN OYSTER

The Eastern Oyster• Crassostrea virginica or American oyster• Bivalve (2 shells)• Lives on bottom • Appearance is due to its habitat• 4-5” typical growth in Choptank and Bay• Native to bay• Found in:

– Eastern coast of the USA to St. Lawrence in Canada to Key Biscayne, FA

– Mexico, Caribbean and Venezuela

The Eastern oyster diet/reproduction

• Eat algae and filter water• Spawn in the water column• Oyster is fertilized and attaches to bottom• Like hard substrate like other oyster shells• Prefer salty water (10-28 ppt)• Once oyster attaches to bottom it is called a

SPAT

Video of Oyster Reproductive Process

• http://hpl.umces.edu/hatchery/home.html

Oyster harvests over the years• 125 yrs - Lt. Francis Winslow - Tangier Sound (1878-1879)

– Spurred into action by the Oyster Wars (Oyster Navy-1868)– 1880 - MD oyster industry valued at $4 million; 24,000 watermen– Principal protein source of the East coast (no railroad)

• 1882 - first MD wide oyster survey (Oyster Commission)• 1884 - estimated 15 million oysters harvested• 1889 - estimated 9.5 million oysters harvested

– 12 watermen killed on Hog Island over oyster dispute

The Oyster Wars

Oyster harvests contd.• Oyster harvested declined for 40 yrs from the high

point in 1884• 1916 - Maryland Conservation Commission formed

– Transplant “stunted” seed oysters – Planting shells for clean substrate attachment (records

from 1939)

• Oysters populations stabilized 1920-1980s, never reached 1800s level again

• 1980s – today - diseases (MSX Dermo) begin to lower harvests

Class Survey

• Do you eat oysters?

• 46.2 % Yes

• 53.8 % No

Don’t Eat My Oysters!

Turbidity and the Oyster

• Turbidity is the cloudiness or haziness of a fluid caused by individual suspended particles

• Suspended soils interfere with the filter feeding and breathing of the oyster

• Silt and other materials can prevent oyster larvae from “setting”

• Turbidity reduces the oyster food supply by blocking light (preventing underwater photosynthesis in algae)

– Email interview with Victor Kennedy - University of MD Center for Environmental and Estuarine Studies Horn Point Environmental Laboratory

Turbidity Sucks

DNR Data

Storm Surge

• A storm surge is an offshore rise in water do to a low pressure weather system

• Storm surges stir up sediment and silt which cause a rise in turbidity in waterways

Say no to storm surge

Issue Web

Players Chart

Our Data

Turbidity Levels in the Choptank RiverHorn Point Pier Site

6/29/2010

Site # Description Water Clarity by Secchi Depth (m) Bottom Depth of the Water (m)site 1 Boat Lanch 0.75 1.90

site 2 Start of the Pier 0.70 0.95site 3 End of the Pier 0.77 0.90site 4 Narrow Channel Start 0.55 1.20site 5 Narrow Channel End 0.55 0.55

Mean 0.66Std Deviation 0.11

Conclusions/Inferences

• The background research shows there is a correlation between turbidity and the health of the eastern oyster

• Our data shows a lower turbidity than the most recent data (as of June) found in the Choptank (via DNR’s monitoring site at Ganey’s Warf Station)

Error/Problems/Issues

• Lack of sampling time• Lack of time• Lack of locations• Lack of data• Sampling of convenience• Boat stirring up water/sediment?• Etc…

Recommendations• More (A LOT) background

research/data is needed for comparison (getting data after storms to see storm surge effects)

• More sampling is needed for reproducibility (over time, location, etc.)

Action Plan

• Educate our students about the problems with the eastern oyster

• Do not buy/eat oysters from the Chesapeake Bay till populations have increased (severely)

• Resurvey the area from time to time to see any future trends

I Pity the Fool Who Eats Choptank Oysters!