Factors Driving Mercury Concentrations in Snapping Turtles

Madeline Turnquist, Charles Driscoll, Martin

Schlaepfer, & Kim Schulz

July 14, 2010

High in trophic position Long life span Small home range Sedentary life style Unique biophysical characteristics At times, consumed by humans

Chelydra serpentina

Description

Largest turtle in NY Omnivores Hibernate in winter Females lay eggs in June Reach sexual maturity late in life (~14yrs or 20cm) High tolerance of pollutants

Habitat

Mainly freshwater Bottom-dwellers

Gibbs et al. 2007

Determine the driving factors for mercury

concentrations in snapping turtles

Examine the correlation between body size and

mercury levels

I hypothesize similar factors driving fish mercury

levels are also driving the levels of mercury in

snapping turtles.

  Measure a correlation between tissue mercury

levels and scute mercury levels in snapping turtles.

I hypothesize a linear increase in shell mercury

concentrations as mercury tissue concentrations

increase.

Lake selection

Hoop nets set with bait for 12-48 hours

Weigh and Measure Turtle

Age Turtle

Take Shell Sample

3rd Pleural scuteT

ake Muscle Sample

from Tail and Legs

Water samples – pH, ANC, DOC, Total Phosphorus

Major AnionsG

IS Data Lake Area Watershed Area % Wetlands % Forests – NLCD Mercury Deposition

Clean and crush shell samples

Total Hg - Milestone – DMA 80

Paired t-test, Two-sample t-test

Pearson’s correlation coefficient (r)

One-way ANOVA

Muscle – 0.041 – 1.50 µg g-1

Shell – 0 .47 – 7.43 µg g-1

Shell 12 times GREATER than muscle

Methyl Mercury – 94%

8 subsamples

US EPA Action Limit – 0.3 µg g-1

Leg and Tail mercury levels significantly different

Collectively – muscle mercury levels not significantly

different

P-value = 0.746S

hell length and weight significantly different

A A ABBBB AB AB AB

n = 7

n = 1

n = 3n = 8

n = 1

n = 2

n = 3

n = 8

n = 4

n = 5

EPA Action Limit (0.3 µg g-1)

n =9

n = 2

n = 3

n = 8

n = 1

n = 3

n = 5

n = 8

n = 4n = 5

EPA Action Limit (0.3 µg g-1)

r = 0.386 p-value = 0.012

Female turtles were smaller than males

Eggs/young potential way to remove Hg

Shell as possible mechanism to eliminate mercury

Useful indicator of Hg level – potential to resample

~38% above EPA action limit

Would not recommend consuming turtles

Sample toe nails for Hg levels – less invasive

Skin samples to test Hg levels

Growth relationship between shell Hg

Mercury in lake sediments

Compare to fish levels

Possibly compare to loon levels

Edna Bailey Sussman Foundation

Maggie Schultz

Martin Schlaepfer

Charles Driscoll

Kim Schulz

NYS Parks and Campsites

Eric Paul and Ben Durie

Ed Mason

Mario Montesdeoca

Bradley Blackwell

Water Chemistry

Low pH <6.0 Low productivity – Total phosphorus < 30 µg/L Dissolved Organic Carbon (DOC) > 4 mg/L Acid-neutralizing capacity (ANC) < 100 µequiv./L

Landscape Characteristics

Presence of wetlands Forest cover Large watershed relative to lake size Mercury deposition

Driscoll et al. 2007

High concentrations in their brains Birth defects Decreased neurological ability of hatchling turtles Lowered population survival Damage to kidneys and renal failure (nephrotoxic)

Lake pHDOC (mg/L)

ANC (µeq./L)

Total Phosphorus (µg/L)

Lake Area (m2)

Watershed Size (m2)

Lake to Watershed Ratio

% Wetlands in Watershed

% Forests in Watershed

Chenango Lake 6.54 2.51 2430 22.56 128645.43 1974600 0.06515 2.37 68.41Cranberry Lake 7.20 3.40 48 19.57 27927481.40 364591800 0.07660 19.23 70.50Delta Lake 8.30 3.50 1040 N/A 10466001.18 378351000 0.02766 14.95 59.38Francis Lake 5.83 3.94 12.13 4.63 575941.03 5603400 0.10278 37.47 51.12Gilbert Lake 6.00 4.10 228 18.73 160031.69 5799600 0.02759 11.92 74.83Hunt's Pond 5.85 4.01 556 23.55 207719.75 2984400 0.06960 3.44 63.12Lake Durant 5.20 9.80 96 23.33 1501123.61 43878600 0.03421 25.40 67.06Montezuma Wetland 7.66 18.39 2550 77.16 1783274.31 3896100 0.45771 26.82 1.85Nick's Lake 4.90 1.80 102 N/A 816755.42 11034000 0.07402 22.72 68.50Putnam Pond 5.50 N/A 112 20.08 1145059.30 15502500 0.07386 7.38 81.09

Natural History

Omnivore Plants, Invertebrates Fish, Birds, Carrion

Active foraging Ambush predator Hibernate in winter Females lay eggs in June High tolerance for polluted waters

Threats

High egg and hatchling mortality Adults vulnerable to road mortality Human persecution

Gibbs et al. 2007