Recent Diatom Changes in the Lake of the Woods …post.queensu.ca/~low/RESEARCH/Cyclotella and Warming/Cyclotella and...Summary of Diatom Trends: ... • Whitefish Bay = case study

Recent Diatom Changes in the Lake of the Woods (Ontario): A Case Study for a Hemispheric-Scale Pattern of Ecological Change

Kathleen Rühland, A.M. Paterson, J.P. Smol

NOTE: Presentation slides are annotated: place cursor over commeNOTE: Presentation slides are annotated: place cursor over comment bubble to toggle on or offnt bubble to toggle on or off

-95°

-95°

-90°

-90°

-85°

-85°

-80°

-80°

-75°

-75°

45° 45°

50° 50°

55° 55°

Manitoba

Ontario

Minnesota

-96º

-96º

-95º

-95º

-94º

-94º

-93º

-93º

49º 49º

50º 50º

0 510

km

OntarioManitoba

Minnesota

Kenora

Lake of the Woods, Ontario, Canada

Big Traverse Bay

Kenora

Modified from Robertson & McCracken 2003

Lake of the Woods, Ontario, Canada

• Main direction of flow is south from the Rainy River to the northern outlet, the Winnipeg River

• Steep gradient in total phosphorus generally follows this direction of flow

August 31st

July 18th

June 19th

Development of an Algal Bloom - 2003

(Terra MODIS images – G. McCullough, U. of Winnipeg)

“The islands were numerous and crowded, the water shoal and foul, frequently with a green scum of vegetable matter”

- Major Joseph Delafield, July 30th, 1823

“…the water became tinged with green, derived from aminute vegetable growth”

- S. J. Dawson, Summer 1857

“…deposits of green vegetable matter” in the lake’s bays during the summer.

- objection to a proposal to use LOW to supply clean water to Winnipeg 1883

Some Important Lake Management Questions:

1) What is the ‘natural’ or baseline condition of the lake?

2) Has the water quality changed since pre-development (or pre-industrial) times?

3) If so, when did these changes occur?

4) What is the direction and magnitude of this change?

5) What are the possible reasons for this change?

Location of sampling sites for sediment cores

Modified from Robertson & McCracken 2003

PP1PP1

Whitefish BayWhitefish Bay

Kenora

BigstoneBigstone BayBay

The Instrumental Record

Historical Lake Ice Records

1960 1970 1980 1990 2000 2010180

190

200

210

220

230

240

250

260y = 0.6556x + 203.64

Year AD

# ic

e-fr

ee d

ays

Rühland, Paterson & Smol: Global Change Biology (2008) 14, doi: 10.1111/j.1365-2486.2008.01670.x

Whitefish Bay Diatom ProfileWhitefish Bay Diatom ProfileReference siteReference site

10 10 10 30 10 10 20 10 10 30 10 30 50 10 20 10 30 50 10 20 10 10 20 10 10 10

% Relative Abundance

20011999199719951993199119881986198319791974

19651970

19601956195219481944194019321926191919111889

Syned

radeli

catis

sima

Fragila

riacro

tonensis

Cyclotel

laste

lligera

/pseudoste

lligera

Cyclotel

labodan

icava

r. lem

anica

Fragila

riaca

pucina va

r. rumpen

s

Asterio

nella form

osa

Cycloste

phanos tholifo

rmis

Stephan

odiscus minutulus

Stephan

odiscus med

ius

Cyclotel

laoce

llata

Aulacose

iraisl

andica

Aulacose

iraam

bigua

Benthic

Fragila

riasp

ecies

Tabell

aria flo

cculosa

str. IV

12 18 24

1980 – present

µg/L

DI-TP

1980

10 30 10 30 5010 30

Rühland et al. in prep

Cyclotel

la

Cyclotel

laco

mensis

comen

sisco

mplex

complex

Aulacose

ira

Aulacose

irasu

barctic

a

subarc

tica

PCA axis 1

-1.5 -1.0 -0.5 0.0 0.5 1.0 1.5 2.0

PCA

axi

s 2

-3

-2

-1

0

1

2

3

1884

2002

1980

Whitefish Bay (reference site)

Summary of Diatom Trends: principal components analysis (PCA)

Rühland et al. in prep

Kenora 100-year Temperature Record

1900 1920 1940 1960 1980 20001.0

1.5

2.0

2.5

3.0

3.5

4.0

Mea

n A

nnua

l Tem

pera

ture

(ºC

)

Year AD

-96º -95º -94º -93º

49º

50º

KenoraKenora

Minnesota

Ontario

Manito

ba

1960 1970 1980 1990 2000 2010180

190

200

210

220

230

240

250

260y = 0.6556x + 203.64

Year AD

# ic

e-fr

ee d

ays

Whitefish Bay Ice Cover Record

• Ice-free period increased by 27.7 days since 1964

• Corresponds to increased temperatures

1960 1970 1980 1990 2000 2010180

190

200

210

220

230

240

250

260

1

2

3

4

5

6

# ic

e-fr

ee d

ays

Year AD

Temperature (ºC

)

R = 0.77

# Ice-free DaysAnnual Temperature


Whitefish Bay (reference site)

Taxon-specific shifts: a closer look at Whitefish Bay


1900 1920 1940 1960 1980 2000 20201.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

0

10

20

30

40

50Annual TemperatureCyclotella spp

Whitefish Bay: Taxon-Specific RelationshipsKenora Temperature Record

1900 1920 1940 1960 1980 2000 20201.0

1.5

2.0

2.5

3.0

3.5

4.0

4.5

10

20

30

40

50

60Annual TemperatureAulacoseira spp

Year AD

R = 0.73

R = - 0.65

Ann

ual T

empe

ratu

re (º

C)

Relative A

bundance (%)


Whitefish Bay Ice-out Record

Whitefish Bay: Taxon-Specific Relationships

1970 1980 1990 2000118

120

122

124

126

128

130

132

134

0

10

20

30

40

50Ice-out DayCyclotella spp

1970 1980 1990 2000118

120

122

124

126

128

130

132

134

10

20

30

40

50

60Ice-Out DayAulacoseira spp

Ice-

Out

Day

of Y

ear

Relative A

bundance (%)

Year AD

R = - 0.76

R = 0.77


Taxon-Specific Shifts: ELA Nitrogen Data

% Cyclotella spp. vs TIN (3 year mean) from 1974-2004

Year (AD)1970 1975 1980 1985 1990 1995 2000 2005

TIN

(mg·

m-2 ·

yr-1 )

250

300

350

400

450

500

550

600

% R

elative Abundance

0

10

20

30

40

50

ELA TINCyclotella spp (%)

R = 0.28p=0.20

Year (AD)1970 1975 1980 1985 1990 1995 2000 2005

250

300

350

400

450

500

550

600

10

15

20

25

30

35

40

45

50

ELA TINAulacoseira spp (% )

R = -0.28p=0.20

TIN

(mg·

m-2 ·

yr-1 )

% R

elative Abundance

% Aulacoseira spp. vs TIN (3 year mean) from 1974-2004


Diatom trends in the Lake of the Woods

Substantial change in last few decadesSubstantial change in last few decades

Impact site: PP-1Reference site: Whitefish Bay

PCA trajectories - ecological threshold passed?

Timing of changes consistent between sites

Diatom trends in the Lake of the Woods

Possible mechanismsPossible mechanisms ((Whitefish BayWhitefish Bay))

Strong relationship to increased temperature

Strong relationship to decreased ice cover

TemperatureTemperature

Inorganic nitrogen deposition (ELA)Inorganic nitrogen deposition (ELA)

strong +ve correlation to increased % Cyclotella spp

Weak correlation to Cyclotella trends

Taxon-specific trends in the Lake of the Woods

strong -ve correlation to decreased % Aulacoseira spp.

IceIce--out day of yearout day of yearstrongly correlated to increase % Cyclotella species

strongly correlated to decrease % Aulacoseira species

Weak correlation to Aulacoseira trends

Physical, chemical & biological changesPhysical, chemical & biological changesDecrease in ice cover duration

Thermal stratificationThermal stratification

Deeper subsurface habitats - nutrients

Planktonic Cyclotella species increase

Longer growing season

Light properties – more stable

Reduction in water column mixing (turbulence)

Warming and diatom changes

Heavier Aulacoseira species decrease

HemisphericHemispheric--scale trendscale trend

Decrease in DI-TP

SpeciesSpecies--specific shiftsspecific shifts

Further reading : Raubitschek et al. 1999 JOPL: Forsström et al. 2005 Polar Biol; Fahnenstiel & Glime 1983 Int Rev Hydrobiol

Cyclotella stelligera/pseudostelligera

Cyclotella comensis/gordonensis

Cyclotella comensis

Cyclotella gordonensis

Planktonic Cyclotella stelligera & C. comensis

From the Lake of the Woods Diatom Taxonomy Workshop: View a pdf of this booklet on our website under Research and Diatoms

Synthesis of Cyclotella/Aulacoseira/Fragilaria trend

1) How many profiles contain Cyclotella species?

2) How many record an increase? A decrease?

3) What do these lakes have in common?

4) Do these profiles show concurrent decreases in Aulacoseira species and/or Fragilaria species?

5) What is the geographic extent of this trend?

6) What are the most plausible mechanisms

• Whitefish Bay = case study

Criteria for Cyclotella compilation

1) Established chronology for last ca. 200 years (i.e. 210Pb dating)

2) At least 2% relative abundance of Cyclotella in at least one interval

3) Increase in Cyclotella = 5% or greater compared to background levels

Results of Cyclotella compilation

• Detailed Cores:• 170 lakes contained Cyclotella deposited within last ca. 200 years

• 14% of these did not have established chronology

• Remaining 147 lakes met first two criteria• 89 lakes (61%) of these showed an increase >5%

- Unimpacted sites• 29% showed a decrease

- 98% of these from eutrophic/acidic lakes• 10% showed no change

• Top-Bottom:• 146 lakes

• 120 recorded increases in Cyclotella from pre-industrial times

Geographic extent of Cyclotella species increases


Subarctic FinlandSorvari et al. 2002Subarctic Canada

Rühland et al. 2003

Great Slave L. N.W.TStoermer et al. 1990

Eastern GreenlandCremer et al. 2001

High Arctic CanadaPerren et al. 2003

SwedenBigler & Hall 2003



Subarctic CanadaRühland et al. 2003

Yukon CanadaKarst-Riddoch et al. 2002


Subarctic FinlandSorvari et al. 2002


Spanish PyreneesCatalan et al. 2002












NB CanadaHarris et al. 2006

SW ONWerner et al. 2005

SE ONForrest et al. 2002

ELA NW ONEnache et al. unpubl.

Northern Hemisphere-Scale Trend

BC CanadaReavie et al. 2005, 2006; Laird et al. 2001


NS CanadaGinn et al. in press




Comparison in the timing of Cyclotella increases

Year AD

Cyc

lote

llare

lativ

e ab

unda

nce

(%)

0

10

20

30

40

50

60 Whitefish Bay Emmett LakeWolfe LakeFairy Lake Indian LakeBig Rideau Lake

1630 1680 1730 1780 1830 1880 1930 1980

05

101520253035404550

Slipper LakeLake SaanajarviLake TK20Lake TK54Lake BirgervatnetLake CF-11

A

B

AD

187

0

AD

197

0

Circumpolar lakes

Temperate lakes

0 10 20 30 40 50 60 70

0

10

20

30

40

50

60

70

0 20 40 60 80 100

0

20

40

60

80

100

0 10 20 30 40 50 60 70

0

10

20

30

40

50

60

70

0 10 20 30 40 50 600

10

20

30

40

50

60

AA

0 20 40 60 80 100

0

20

40

60

80

100

0 20 40 60 80

0

20

40

60

80

P<0.010 P<0.012

P<0.003 P<0.011

P<0.001P<0.001

1:11:1

1:1 1:1

1:11:1

Climatic Warming and Taxon-specific Shifts

Pre-industrial Sedimentary Diatoms

Mod

ern

Sedi

men

tary

Dia

tom

s

South-western OntarioSouth-central OntarioSouth-eastern Ontario

BB

CC DD

EE FF

% C

yclo

tella

spp

% C

yclo

tella

spp

% C

yclo

tella

spp

% A

ulac

osei

rasp

p%

Aul

acos

eira

spp

% F

ragi

laria

spp

Cyclotella

Fragilaria/Aulacoseira

1.1. NWT-Nunavut (n=40)Rühland et al. 2003 AAAR

2.2. New Brunswick (n=16)Harris et al. 2006 CanJBot

3.3. Ontario Combined (n=91)Hall & Smol 1996 CanJFishAquat Sci

Reavie et al. 2002 Hydrobiol

Werner 2003 PhD thesis


Climatic Warming and increases in Cyclotella species








NB CanadaHarris et al. 2006

SW ONWerner et al. 2005

SE ONForrest et al. 2002

ELA NW ONEnache et al. unpubl.

Northern Hemisphere-Scale Trend

BC CanadaReavie et al. 2005, 2006; Laird et al. 2001


NS CanadaGinn et al. in press


Summary of Results: Lake of the Woods

• Greatest change in diatom composition over last ca. 20-30 yrs

• Changes consistent with climate records

• Taxon-specific shifts correlated to increase in temperature

• Taxon-specific shifts correlated to decrease in length of ice cover

• Taxon-specific shifts not related to nitrogen deposition

• Climatically-induced limnological changes = 1º mechanism

• Climate must be included in lake management strategies

• LOW fits into global pattern of recent taxon-specific diatom shifts

Acknowledgements

• Bev Clark (MOE, Dorset)

• Mike Stainton (DFO, MB)

• Sergi Pla (formerly at PEARL)

• Tom Mosindy & Gavin Olson (MNR Kenora)

• Ron Ingram (MOE, Dorset)

• Joy Ramstack (St. Croix Watershed Research Station, MN)

• Mark Edlund (St. Croix Watershed Research Station, MN)

• Euan Reavie (Natural Resources Research Institute, Ely MN)

• Nolan Baratono (Minnesota Pollution Control Agency)

Documents

Recent Diatom Changes in the Lake of the Woods …post.queensu.ca/~low/RESEARCH/Cyclotella and Warming/Cyclotella and...Summary of Diatom Trends: ... • Whitefish Bay = case study