factors driving mercury concentrations in snapping turtles
DESCRIPTION
Factors Driving Mercury Concentrations in Snapping Turtles. Madeline Turnquist , Charles Driscoll, Martin Schlaepfer, & Kim Schulz July 14, 2010. Why Study Turtles for Mercury?. High in trophic position Long life span Small home range Sedentary life style - PowerPoint PPT PresentationTRANSCRIPT
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