Current-use pesticides and Current-use pesticides and salmon neurophysiology: salmon neurophysiology: Implications for salmon in Implications for salmon in

British ColumbiaBritish Columbia

Keith Tierney, Keith Tierney, Peter S. Ross, Chris KennedyPeter S. Ross, Chris Kennedy

Salmon are at riskSalmon are at risk• Over the last 150 years, salmon have disappeared from almost Over the last 150 years, salmon have disappeared from almost

half of their original range along the west coast half of their original range along the west coast Cone and Ridlington 1996Cone and Ridlington 1996

• Various salmon stocks are listed under the Endangered Species Various salmon stocks are listed under the Endangered Species Act in the US and the Species at Risk List in CanadaAct in the US and the Species at Risk List in Canada

US Federal Register 1991, US Federal Register 1991, 19981998

COSEWIC 2002COSEWIC 2002

• Some coho stocks from the Interior Fraser River have declined Some coho stocks from the Interior Fraser River have declined by 60% since 1996 by 60% since 1996

COSEWIC 2002COSEWIC 2002• Recovery is uncertain Recovery is uncertain

Lackey 2003Lackey 2003

• Salmon life history places them at risk for pesticide exposure…Salmon life history places them at risk for pesticide exposure…

Diazinon disrupts homingDiazinon disrupts homing

Chinook salmon… Chinook salmon… released 2 km released 2 km downstream after downstream after diazinon exposurediazinon exposure

Scholz et al. (2000) CJFAS 57: 1911-1918

acetone 0.1 1 100

20

40

60

80

100

120

(16)

(12) (12)

*(6)

% r

etur

ns (

rela

tive

to c

ontr

ols)

Diazinon exposure (µg/L)

Why study salmon olfaction?Why study salmon olfaction?

Smell is for… Smell is for… • kin and conspecific kin and conspecific

recognition recognition • alarm responsealarm response• imprinting, thusimprinting, thus

• hominghoming• gamete release gamete release

synchronizationsynchronization

• contaminant contaminant avoidanceavoidance

Our research questionsOur research questions

• How do currently-used pesticides alter How do currently-used pesticides alter the sense of smell (olfaction) in salmon?the sense of smell (olfaction) in salmon?– (A) Physiological response(A) Physiological response

• How do alterations in olfaction relate to How do alterations in olfaction relate to changes in two olfactory-mediated changes in two olfactory-mediated behaviors?behaviors?– (B) Alarm response(B) Alarm response– (C) Preference response(C) Preference response

Pesticides in salmon producing Pesticides in salmon producing waterways of BCwaterways of BC

Nathan Creek Musqueam Creek Nicomekl River

Peter RossPeter Ross Peter RossPeter Ross Mark SekelaMark Sekela

spring (2004) spring (2004) (2003)

ng/L ng/L ng/L

MCPP 45 β-endosulphan 3.33 Dimethoate 604

2,4-D 38.5 MCPA 2.45 Simazine 84.5

MCPA 27.4 MCPP 2 Methamidophos 61.4

Simazine 22.3 Chlordane (α) 0.431 Diazinon 48.7

Dimethoate 8.34 Diazinon 0.375 Chlorpyriphos 18.3

Dicamba 4.52 Linuron 0.305Endosulphan-Sulphate 15

Atrazine 3.94 Nonachlor trans 0.268 Malathion 10

Triclopyr 3.23Chlordane (γ) trans 0.199 Atrazine 6.8

Methamidophos 2.78 Alachlor 0.184 Linuron 6.3

Diazinon 2.39 Metrabuzin 0.174 Parathion-Ethyl 4.8

(A) Physiological response(A) Physiological responsethe electro-olfactogram (EOG)the electro-olfactogram (EOG)

7 mV 3.5 mVΔ EOGΔ EOG

1- (3.5 / 7) = 1- (3.5 / 7) = 0.50.5

oror 50% loss50% loss

Moran et al. 1992

EOG recording electrodeEOG recording electrode

indifferent electrodeindifferent electrode

Time (each division 2 s)

Pre-exposure 30 min of exposure2 min of exposure 2 min post-exposure 60 min post-exposure

Example: effects of 10 mg/l glyphosate

heart rate

odorant?odorant?

Tierney et al. (2006) ET&C 25: 2809-2817

exposure recovery

*RM ANOVA, HS, p<0.05

RoundupRoundup®® alters EOG alters EOG

100

0 10 20 30 40 500

50

100

150

200

100

μg/l

1000

% p

re-e

xp

osu

re E

OG

time (min)

*

* *

KB Tierney et al. (2007) Aquatic Toxicology 81: 55–64

Roundup is 10 to 100 x more toxic than pure glyphosate

exposure recovery

*RM ANOVA, HS, p<0.05

Atrazine alters EOGAtrazine alters EOG%

pre

-exp

osu

re E

OG

time (min)

0 10 20 30 40 500

50

100

150

200

Note: same 12% decrease w/ 1 μg/l as Moore & Lower 2001 (Note: same 12% decrease w/ 1 μg/l as Moore & Lower 2001 (S. salarS. salar))

1

10

100

0

μg/l

**

KB Tierney et al. (2007) Aquatic Toxicology 81: 55–64

Salmonids are differentially Salmonids are differentially sensitive to pesticidessensitive to pesticides

• L-serine-evoked EOGs after linuron:L-serine-evoked EOGs after linuron:

• Note: rainbow were less sensitive, but didn’t Note: rainbow were less sensitive, but didn’t recoverrecover

0 10 20 30 400 10 20 30 400 10 20 30 400.0

0.2

0.4

0.6

0.8

1.0

1.2

1.4

1.6

1

µg/L

00 0

10

10

100

10

sockeye salmonsockeye salmoncoho salmoncoho salmon rainbow troutrainbow trout

µg/L µg/L

exposure recovery exposure recovery exposure recovery

time (min)

KB Tierney et al. (2007) Toxicology 231:175–187

*RM ANOVA, HS, p<0.05

(B) Behaviour: alarm response(B) Behaviour: alarm response What does a decrease in EOG mean? What does a decrease in EOG mean?

Fish is injured (rupture of skin)Fish is injured (rupture of skin)

release of alarm pheromonerelease of alarm pheromone

flight, then sheltering behaviorflight, then sheltering behavior

Exposure to Exposure to pesticide or pesticide or vehicle vehicle controlcontrol

Alarm Alarm pheromonepheromone

exposureexposure

MeasureMeasure

changes in:changes in:

1)1) behavior behavior

2)2) physiologyphysiology

IPBC alters alarm responseIPBC alters alarm response

[IPBC] (µg/l)

0 1 10 100

Freezing(3rdmin)

-20

-10

0

10

20

**

*

Vehicle controls were for polyethylene glycol (PEG)

Stats: two-sample t-test, n = 6 tanks of five fish per point

KB Tierney et al. (2006) Aquatic Toxicology 79(2):149-157

beh

avio

ral c

han

ge (

%)

50 mg/L of ‘skin extract’ released into 35L aquaria,averages for 3-min before vs. 3-min after

(C) Behavioral testing: the avoidance trough(C) Behavioral testing: the avoidance trough

0 sec

30 sec

1 min

2 min

10 min

• EndpointsEndpoints– Do they avoid the pesticides?Do they avoid the pesticides?– Is attraction to AA altered?Is attraction to AA altered?

Fish position is recorded by 5 camerasconnected to a P4 PC

10 L 10 L

120 L

IPBC, atrazine, RoundupIPBC, atrazine, Roundupimpair attraction responseimpair attraction response

1 10 1000 1 10 100 10 100 10000 0

(a) IPBC (b) atrazine (c) glyphosateRoundup® formulation

0.0

1.0

1.5

2.0

10-m

in r

atio

pesticide (µg/L)

*

***

*

*n=6 per concentration; RM ANOVA, p<0.05

attraction loss

repulsion

hyperactivehypoactive

KB Tierney et al. (2007) Aquatic Toxicology 81: 55–64

L- histidine attraction and repulsion after 30-min exposureL- histidine attraction and repulsion after 30-min exposure

Behavioural responses at more Behavioural responses at more sensitive than neurological resp.sensitive than neurological resp.

% neurological reduction % neurological reduction 0 20 40 60 80 100

SNS

S

S

S S

SS

IPBCatrazine

0

20

40

60

80

100

% b

ehavio

ura

l re

duct

ion

% b

ehavio

ura

l re

duct

ion

• Loss ≥60% of olfactory Loss ≥60% of olfactory neuron response means neuron response means 100% loss of olfactory-100% loss of olfactory-mediated behaviors.mediated behaviors.

• Small neurological losses Small neurological losses can cause a can cause a disproportionate amount of disproportionate amount of behavioural losses:behavioural losses:

– 10.9% neural response 10.9% neural response loss following 1 μg/l loss following 1 μg/l atrazine exposure equated atrazine exposure equated to 45.4% loss behavioural to 45.4% loss behavioural response.response.

30-min exposures to: 30-min exposures to:

RoundupNS

KB Tierney et al. (2007) Aquatic Toxicology 81: 55–64

ConclusionsConclusions

• Olfaction can be rapidly perturbed by Olfaction can be rapidly perturbed by pesticidespesticides

• This can lead to a disproportionate loss of This can lead to a disproportionate loss of olfactory behaviorsolfactory behaviors

• Species-specific pesticide sensitivities exist Species-specific pesticide sensitivities exist for salmonfor salmon

• Future: what effect does a mixture have on Future: what effect does a mixture have on olfactory tissue?olfactory tissue?– 96-hr exposure to 0.1, 1, 1096-hr exposure to 0.1, 1, 10×× Nicomekl R. Nicomekl R.

• Week of Jan. 27, 2007; Vol. 171, No. 4Week of Jan. 27, 2007; Vol. 171, No. 4

Thanks…Thanks…

• Funding:Funding:– National Pesticide Research Fund of Fisheries National Pesticide Research Fund of Fisheries

and Oceans Canada to Peter Ross and Chris and Oceans Canada to Peter Ross and Chris KennedyKennedy

– NSERC grants to Keith Tierney and Chris NSERC grants to Keith Tierney and Chris KennedyKennedy

– Garfield-Weston / BC Packers award to Keith Garfield-Weston / BC Packers award to Keith TierneyTierney

• Undergrad helpers: Undergrad helpers: – Jessica Sampson, Chris Singh, Amber TaylorJessica Sampson, Chris Singh, Amber Taylor