Pesticides in Amphibian Habitats of Central and Northern California

Chapter 7

Downloaded by UNIV OF AUCKLAND on May 3, 2015 | http://pubs.acs.org Publication Date (Web): November 8, 2013 | doi: 10.1021/bk-2013-1149.ch007

Pesticides in Amphibian Habitats of Central and Northern California, USA Gary M. Fellers,*,1 Donald W. Sparling,2,† Laura L. McConnell,3 Patrick M. Kleeman,1 and Leticia Drakeford3,‡ 1U.S.

Geological Survey, Western Ecological Research Center, Point Reyes National Seashore, Point Reyes, California 94956, USA 2U.S. Geological Survey, Patuxent Wildlife Research Center, Laurel, Maryland 20708, USA 3U.S. Department of Agriculture, Agriculture Research Center, BARC-W, Beltsville, Maryland 20705, USA *E-mail: [email protected] †Present address: Cooperative Wildlife Research Laboratory, Southern Illinois University, Carbondale, Illinois 62901, USA ‡Present address: U.S. Department of the Treasury, Alcohol and Tobacco Tax and Trade Bureau, Beltsville, Maryland 20705, USA

Previous studies have indicated that toxicity from pesticide exposure may be contributing to amphibian declines in California and that atmospheric deposition could be a primary pathway for pesticides to enter amphibian habitats. We report on a survey of California wetlands sampled along transects associated with Lassen Volcanic National Park, Lake Tahoe, Yosemite National Park, and Sequoia National Park. Each transect ran from the Pacific coast to the Cascades or Sierra Nevada mountains. Pacific chorus frogs (Pseudacris regilla), water, and sediment were collected from wetlands in 2001 and 2002. Twenty-three pesticides were found in frog, water, or sediment samples. Six contaminants including trifluralin, α-endosulfan, chlordanes, and trans-nonachlor were found in adult P. regilla. Seventeen contaminants were found in sediments, including endosulfan sulfate, chlordanes, 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene (4,4′-DDE), and chlorpyrifos. The mean number of chemicals detected per pond in sediments was 2.4 (2.5, standard deviation). © 2013 American Chemical Society In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health; McConnell, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013.


In water, 17 chemicals were detected, with β-endosulfan being present in almost all samples. Trifluralin, chlordanes, and chlorpyrifos were the next most common. The mean number of chemicals in water per pond was 7.8 (2.9). With the possible exception of chlorpyrifos oxon in sediments and total endosulfans, none of the contaminants exceeded known lethal or sublethal concentrations in P. regilla tissue. Endosulfans, chlorpyrifos, and trifluralin were associated with historic and present day population status of amphibians. Cholinesterase, an essential neurological enzyme that can be depressed by certain pesticides, was reduced in tadpoles from areas with the greatest population declines.

Introduction Global declines of amphibian populations have been well documented, and many causes have been suggested for these declines including habitat loss and degradation, diseases such as chytridiomycosis, climate change, ultraviolet radiation, introduced predators, and contaminants (1). The Central Valley of California, USA, is an extremely productive agricultural area. Each year hundreds of thousands of kg of active ingredient pesticides are applied to crops. These chemicals can volatilize and be carried by wind currents for long distances (2) where they are deposited in some of our largest parks and wilderness areas (3). There they can come into contact with aquatic organisms including amphibians. Several studies have found measurable concentrations of pesticides and other organic contaminants in air, snow, water, and sediments of wetlands inhabited by California amphibians (3–6), as well as in frog tissues (7–10). Some of these pesticides can be lethal at a few parts per billion, within the range of environmentally realistic concentrations (11, 12). In addition, sublethal concentrations can reduce rates of growth and development, and thus affect tadpole survival (13). Other pesticides induce endocrine effects that may alter reproductive success (14). The purpose of our study was to describe pesticide concentrations in water, sediment, and Pacific chorus frog (Pseudacris regilla) tissue over a two year period, and a broad geographic area extending from the Pacific coast through the Central Valley to the Cascades or Sierra Nevada mountains. The null hypotheses we tested were: 1) there are no apparent north-south or west-east trends in pesticide concentrations within central and northern California; 2) historic and present day status of amphibian populations are not related to pesticide concentrations, and 3) cholinesterase concentrations in adult and larval treefrogs do not differ geographically, or between populations showing declines or not.

124 In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health; McConnell, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013.

Material and Methods


Frog, Tadpole, Water, and Sediment Samples Pseudacris regilla adults and tadpoles, sediment, and water were collected in 2001 and 2002 along four transects that began at the Pacific coast and extended east to montane sites in the southern Cascades and the Sierra Nevada: Lassen, Tahoe, Yosemite, and Sequoia (Figure 1). From north to south the transects were: Fort Bragg to Lassen Volcanic National Park; Point Arena to Lake Tahoe; Point Reyes National Seashore to Yosemite National Park; and Piedras Blancas to Sequoia National Park. Sampling occurred at five locations along each transect: Coast (3 – 66 m elevation), Coast Range mountains (Range; 131 – 691 m), eastern edge of the Central Valley (Valley; 61–150 m.), Cascades/Sierra Nevada foothills (Foothill; 265– 858 m), and mid-elevation of the Cascades/Sierra Nevada (Montane; 1887 – 2359 m). The Point Reyes to Yosemite transect had an additional high-elevation location near Tioga Pass in Yosemite (Alpine; 2605 – 3019 m).

Quality Assurance/Quality Control All solvents utilized in this study were reagent grade or chromatographic grade from Fisher Scientific (Springfield, NJ, USA). All solid reagents such as drying agents and laboratory sand or other chemicals used in sample processing were high purity/analytical grade and were also purchased from Fisher Scientific. Organic carbon-free de-ionized water was produced using an in-house system by Hydro Service and Supplies, Inc. (Durham, NC, USA). After collection, samples were kept on dry ice in the field and shipped by overnight delivery to USDA in Beltsville, MD. All glass jars and other glassware used in sample collection and processing were cleaned with laboratory detergent, rinsed with copious quantities of tap water, followed by organic-carbon-free de-ionized water, chromatographic grade acetone, followed by baking in a large muffle furnace at 300 °C for at least 4 h. High purity standards (≥ 98% purity) were used for all analytes (Table I) from Chem Service, Inc. (West Chester, PA, USA), Sigma Aldrich (St. Louis, MO, USA), or Cambridge Isotopes (Tewksbury, MA, USA). The compound PCB 204 (2,2′,3,4,4′,5,6,6′-octachlorobiphenyl, CAS Number 2051-24-3) was used as the internal standard. A five-point calibration curve spanning the range of sample response was established for each compound and instrument response was linear over the calibration standards range (r2 ≥ 0.99).



Figure 1. Map of California, USA showing the four transects and locations of the wetlands sampled along with National Parks of interest.


Table I. Target analytes with method detection limits (MDLs) and average percent spike recovery values for sample matrices.

127


Method Detection Limita

Mean Percent Spike Recovery

Water

Sediment

Amphibian

Water

Sediment

Amphibian

Common Name

ng/L

ng/g d.w.

ng/g fr.wt.

Percent ± standard deviation

aldrin

nab

0.37

0.22

na

100±19

75±5

α-chlordane

0.7

0.52

0.21

58±15

116±21

79±6

γ-chlordane

0.2

0.37

0.16

85±11

115±20

79±6

chlorothalonil

0.2

0.08

0.08

95±12

26±8

98±17

chlorpyrifos

0.2

0.32

0.24

97±11

94±19

78±6

chlorpyrifos oxon

2.0

3.0

1.9

111±4

114±22

96±31

4,4′-DDDc

na

0.64

0.23

na

91±66

79±7

4,4′-DDEd

0.3

0.57

0.23

78±6

107±43

73±5

2,4′-DDTe

0.3

na

na

120±13

na

na

4,4′-DDTf

0.7

2.0

na

81±9

14±63

na

diazinon

1.2

4.6

0.93

74±36

80±87

94±29

dieldrin

na

0.89

0.16

na

103±20

95±5

α-endosulfan

0.1

0.32

0.17

99±4

93±21

79±6

β-endosulfan

0.2

0.15

0.20

98±1

95±21

79±6

endosulfan sulfate

0.3

0.28

0.26

87±2

89±21

92±16 Continued on next page.

In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health; McConnell, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013.

Method Detection Limita

128


Table I. (Continued). Target analytes with method detection limits (MDLs) and average percent spike recovery values for sample matrices. Mean Percent Spike Recovery

Water

Sediment

Amphibian

Water

Sediment

Common Name

ng/L

ng/g d.w.

ng/g fr.wt.

Percent ± standard deviation

fipronil

na

0.25

1.8

na

50±20

62±15

heptachlor

na

0.31

0.29

na

118±24

109±6

heptachlor epoxide

na

0.25

na

na

110±21

na

α-HCHg

0.1

0.53

0.21

78±7

86±17

76±6

γ-HCHh

0.2

0.16

0.20

95±8

91±17

78±5

malathion

1.6

1.8

0.80

109±12

49±106

115±6

mirex

na

0.35

0.28

na

112±21

60±8

cis-nonachlor

na

0.67

0.23

na

137±23

82±6

trans-nonachlor

0.4

0.66

0.22

59±7

136±24

81±6

oxychlordane

na

0.39

na

na

101±21

na

trifluralin

0.2

0.33

0.17

87±6

63±18

87±5

a

Amphibian

Method detection limits provided assume a water sample volume of 10 L, a sediment sample dry weight (d.w.) of 10g, and an amphibian sample mass of 10g. Actual sample volumes and masses varied. Sediment MDL in ng/g dry weight, and amphibian MDL in ng/g fresh weight. b na = not analyzed. c 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethyl]benzene. d 1-chloro-4-[2,2-dichloro-1-(4-chlorophenyl)ethenyl]benzene. e 1-chloro-2[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene. f 1-chloro-4-[2,2,2-trichloro-1-(4-chlorophenyl)ethyl]benzene. g (1α,2α,3β,4α,5β,6β)-1,2,3,4,5,6-hexachlorocyclohexane. h (1α,2α,3β,4α,5α,6β)-1,2,3,4,5,6-hexachlorocyclohexane, also known as lindane.

In Occurrence, Fate and Impact of Atmospheric Pollutants on Environmental and Human Health; McConnell, L., et al.; ACS Symposium Series; American Chemical Society: Washington, DC, 2013.


The mass spectrometer was tuned prior to each sequence of samples to evaluate the instrument performance, and chromatographic conditions were monitored closely to maintain consistent response factors and peak shape. The mass spectrometer was recalibrated every 20 to 25 sample injections. Quantification of each compound was calculated based on the area of the ion with the largest abundance. Confirmation of a particular compound in a sample was determined by the presence of at least one of the two qualifying ions in the proper ratio to the quantifying ion (± 20%). The requirement for only one qualifying ion in the proper ratio is due to the use of the ECNI mode where the number of ions in the mass spectra is often dominated by one or two ions, with very small contributions from other ions. Method detection limits (MDLs) were determined for each analyte (16) (Table I). MDLs for water were

Pesticides in Amphibian Habitats of Central and Northern California

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