Under the Radar: Long-term perspectives on ecosystem changes in - - PowerPoint PPT Presentation

Under the Radar:

Long-term perspectives on ecosystem changes in lakes

John P. Smol

Professor and Canada Research Chair in Environmental Change

Paleoecological Environmental Assessment and Research Laboratory (PEARL) Queen’s University, Kingston, Ontario, Canada

SmolJ@QueensU.Ca

Notwithstanding major advances in our lives, our relationship with the environment has been riddled with unintended consequences.

http://seedmagazine.com/content/world/ http://tothewire.wordpress.com/2009/08/21/the-anthropocene-era-is-man-dominating-nature/

The Anthropocene: The period of human-dominated Earth’s history

Important management questions

What were pre-disturbance conditions? What is the range of natural variability? Have conditions changed? How much? How fast? When? Why?

Smol, 2019, Proc Roy Soc B

Techniques to Assess Environmental Change historical records and traditional knowledge modeling natural archives

• utside

material

e.g. pollen grains

within lake material

e.g. algae & aquatic insects

Paleolimnology: Sediments as environmental archives

e.g. soil particles e.g. aerially transported contaminants

Surface sediment gravity coring

Close-interval sectioning

2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32 34 36

• 5

5 10 15 20 25 30 35 40 45 50 214Bi 137Cs 210Pb

Core Depth (cm)

Dating the sedimentary sequences

• 210Pb & 137Cs (radioisotopes)

2002 2001 1999 1998 1996 1994 1992 1990 1987 1985 1981 1976 1972 1965 1950 1946 1936 1926 1920 1900 1890 1870 1860 1856 1850 1846 1910 2003 2004 2005 2006

Youngest Oldest

Continuous Record

Activity (dpm/g)

~1963

From the Atmosphere

carbon particles from carbon combustion fly ash from coal combustion metals and other pollutants from industry

From the Catchment

pollen mineral particles insect remains

beetle wing

algae cladocerans chironomids

From the Aquatic System

In addition to morphological fossils, there is a growing suite of biogeochemical indicators.

Phycoerythrin

(e.g. fossil pigments, environmental DNA, etc.)

Redrawn from: Leeming et al. 1996 Water Res.

Sterols & stanols

Select Study Lake Collect Indicator Data Sub-sample Sediments & Isolate Indicator of Interest Analyze Data Section & Date Sediment Core Select Coring Site & Retrieve Sediment Core

The Paleolimnological Approach

Photos courtesy of B. Cumming, I. Walker, Dell & Leic

210Pb 137Cs 14C

• Targets
• Trajectories

What factors can be addressed using paleolimnology?

eutrophication anoxia and fish habitat climate change acidification groundwater quality river paleoecology fire history species invasion speciation / evolution, etc.

Eutrophication

Impacts of Cultural Eutrophication

• hypolimnetic anoxia
• fish kills
• P release
•  accumulation and decay
• shoreline fouling
•  plant growth
•  algal growth and toxins
• taste and odour problems
• presence of undesirable species
• aesthetic degradation

Three lake characteristics we typically wish to track

1) Lakewater nutrient levels 2) Deepwater oxygen levels 3) Algal and cyanobacterial blooms

1) Trends in lakewater nutrients

Why not just measure total P in the sediments?

Many pitfalls and largely abandoned ~30 years ago

(this is not to say that sedimentary P has no value in other applications – very important in mass balance studies and determining processes, etc.)

So we have to use indirect proxy methods that are related to lakewater total phosphorus (TP)

Research ongoing for over 30 years, but especially last 20 years

Freshwater diatoms

Photos: K. Laird and B. Cumming; Fig. 5.5 in Smol (2008)

Abundance of taxa Environmental variable (e.g. TP)

• sp. 1
• sp. 2
• sp. 3
• sp. 4
• sp. 5
• sp. 6

Develop a “paleo TP meter”

2) Deepwater oxygen levels?

Use organisms that need oxygen, and live in the deep waters

http://www.nzfreshwater.org/food.html

(Drawing: Walker 1987)

Chironomid life cycle

http://www.ec.gc.ca/ceqg-rcqe/images/SAS/fact3_img2.jpg

Chironomid head capsules as indicators

Chironomus Chironomus mentum

5 mm

Using fossil assemblage data we develop a “paleo-oxygen meter”.

3) Algal and cyanobacterial blooms

Photo Todd Sellers

Not all groups leave reliable morphological fossils Biogeochemical indicators, such as fossil pigments, DNA, and preserved microcystin toxins may be used.

Increasing cyanobloom reports across Ontario

Winter et al. 2011, Lake and Res. Manage., Updated by OMOECP 2018; M. Palmer (unpub. Data)

• 26% from oligotrophic lakes

(Winter et al. 2011)

2009 2010 2011 2012 2013 2014 14 17 19 24 25 31 31 27 16 51 51 54 66

10 20 30 40 50 60 70

# reports confirmed as blooms

Blue-green algae (cyanobacteria) blooms

Climate change: The new “threat multiplier”

www.ccepr.org/liu/researchCC_en.html

Without question, you need a minimum amount of nutrients (P, N, etc.) to generate algal biomass. But people are recording increased algal blooms, even in lakes with steady or declining nutrient levels.

Can climate change be affecting algal blooms, even without increases in nutrients?

1) The “longer summer” (less ice cover) 2) Enhanced thermal stratification

Example #1

Lake of the Woods

(almost a Great Lake - 2 provinces and 1 state)

P load from Rainy River decreased from ~1500 t/year (1960- 1975) to ~500 t/year (post-1990) (Reavie et al. 2017 LRM)

LOW: External phosphorus load

(Hargan et al. 2011)

Rainy River = primary source of TP to LOW

HIGHER P LOWER P

AND YET…

nuisance algal blooms are being reported

Satellite image of blue-green algae blooms widespread across LOW,

• Sept. 1, 2015.

Credit: MODIS, University of Wisconsin Space Science and Engineering Center Susie the dog surveys an algal bloom in October. Credit: Todd Sellers

(Photo: T. Sellers)

Perception blue-green blooms have increased in intensity and duration in recent years.

=

A decline in TP loading.

Is there a disconnect in Lake of the Woods?

42

Whitefish Bay TP <10 µg/L

1975

% Relative Abundance

Rühland et al. 2010. Limnol. Oceanogr.

Whitefish Bay – Reference site

Lake of the Woods, Canada and USA - temperature

Rühland, Paterson, Smol 2008: Global Change Biology Annual Temperature Cyclotella spp Aulacoseira spp

Annual Temperature (ºC) Relative Abundance (%)

1900 1920 1940 1960 1980 2000 2020 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 10 20 30 40 50

R = 0.73

1900 1920 1940 1960 1980 2000 2020 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 10 20 30 40 50 60

Year AD

R = - 0.65

Rühland, Paterson, Smol 2008: Global Change Biology

1970 1980 1990 2000 118 120 122 124 126 128 130 132 134 10 20 30 40 50 1970 1980 1990 2000 118 120 122 124 126 128 130 132 134 10 20 30 40 50 60

Ice-Out Day of Year Relative Abundance (%) Year AD

R = - 0.76 R = 0.77

Whitefish Bay – Reference site

Ice-out day of year Cyclotella spp Aulacoseira spp

Lake of the Woods, Canada and USA – lake ice data

How will this affect other algae and cyanobacteria?

Potential triggers for algal blooms on LOW

Have lake TP concentrations increased over time?

NO

Consistent with declines in TP loading to Rainy R. (and with limited monitoring data)

(Photo: T. Sellers)

Perception that blue green blooms have increased in intensity and duration in recent years

Perception is correct

but warming is likely playing a key role

Is there a disconnect in Lake of the Woods?

Diatom-inferred TP

48

Applied the Hyatt et al. (2011) TP model (R2

boot=0.58, RMSEP=0.15)

Rühland et al. 2010. Limnol. Oceanogr.

TP <10 µg/L TP >12 µg/L TP >14 µg/L Sediment chl a (and its main diagenetic products) also increase with warming/thermal stability, provided a nutrient threshold is reached.

Paterson et al. 2017. LRM

Blue-greens like it hot!

EXACERBATES BLOOMS

Weakly mixed/increased thermal stability

Strongly mixed water column

Stronger mixing and/or longer ice-cover period Stratified and/or longer open water period

Even without further increases in nutrients

Are the blooms cyanobacteria??

(eDNA and microcystin toxins preserved in LOW sediment cores) Pilon et al. 2019, LRM microcystin-synthesizing gene proxy of bg abundance present in all bacteria

Example #2

Can too little of something cause an algal bloom?

Calcium declines in lakes – A legacy of acid rain?

X

“Aquatic Osteoporosis” The widespread threat of calcium decline in fresh waters

Lake [Ca] Decline

Jeziorski, A., Yan, N.D., Paterson, A.M., DeSellas, A.M., Turner, M., Jeffries, D., Keller, W., Weeber, R., McNicol, R., Palmer, M., McIver, K., Arseneau, K., Ginn, B., Cumming, B., and Smol, J.P. (2008) Science 322: 1374-77.

• Ont. Min. Env. Climate Change

• Ont. Min. Env. Climate Change

Calcium Decline/ “Aquatic Osteoporosis”

◼ Declines in lakewater calcium (Ca)

concentrations have been observed in many regions of Eastern N.A. and Europe

◼ Due to a lack of baseline data, some

questions can only answerable using paleolimnological techniques

Mechanism of Ca Decline

Atmospheric Deposition of Ca Mineral Weathering Forest Growth/ Tree Harvesting Leaching

Inputs Outputs

Exchangeable Soil Calcium

Acid Rain

Crustacean Zooplankton: Major grazers in lake systems

◼ Crustacean zooplankton have a direct

dependence upon Ca (used as a structural material in the carapace)

◼ Species-specific [Ca] requirements ◼ Leave identifiable remains that preserve well in

sediments (head-shields, carapaces, ephippia)

Field Analyses

◼ Analyzed Ca content

• f crustacean

zooplankton common to Ontario softwater lakes

◼ Significant

differences identified among zooplankton taxa

◼ Members of Daphnia

• spp. have much

higher Ca concentration

(Jeziorski & Yan 2006, CJFAS)

Calcium and the Crustacean Zooplankton

Species Calcium content (% dry weight)

0.0 2.0 4.0 6.0 8.0 10.0

Bosmina

• L. minutus
• M. edax
• H. gibberum
• D. ambigua
• D. catawba
• D. mendotae
• D. pulex

A A A A B C C C

(Jeziorski and Yan, 2006)

Laboratory Analyses

◼ Experimental analysis of

Daphnia pulex in culture have identified a Ca threshold of 1.5 mg/L

(Ashforth and Yan, 2008, L&O)

Daphnia – certain species very sensitive to Ca levels

[Calcium]

1.5 mg/L Daphnia spp. Bosmina spp.

1970 1980 1990 2000 2010 1.0 1.5 2.0 2.5 3.0 3.5

Ca - ice free season average (mg/L) year

BC CB CN DE HP HY PC RC

Reproductive threshold for Daphnia pulex

Lake [Ca] Decline

[Ca] of the Dorset “A” Lakes

Slide: S Azan

Next Logical Step

◼ Application of the field and laboratory findings

back through time via lake sediments

3 Acidification Scenarios

All decreased in [Ca]; similar Daphnia responses

(Jeziorski et al., 2008, Science)

[Ca] decline

Never acidified Naturally acidic Acidified but recovered in pH

The Threat of Multiple Stressors – A legacy of acid rain? Can changing food web structure affect algal blooms?

X

Yet nutrients are not necessarily increasing?

P Ca

X X X X

Can we get algal blooms even without an increase in P & N?

Ca decline

Fossil pigments Fossil Cladocera

The jellification of north temperate lakes

Jeziorski, A., Tanentzap A.J., Yan, N.D., Paterson, A.M., Palmer, M.E., Korosi J.B., Rusak, J.A., Arts, M. T., Keller, (W) B., Ingram, R., Cairns, A. and Smol, J.P. 2015. Proc. Royal Soc. Lond. B.

Holopedium gibberum/glacialis

◼ Planktonic taxon

in competition with Daphnia spp.

◼ Acid-tolerant ◼ Jelly-capsule vs.

calcified carapace

(Jeziorski and Yan, 2006)

Holopedium glacialis

Ian Gardiner, www.nikonsmallworld.com

Surrounded by a jelly capsule, making it less available as a prey item, and also much lower in nutrient content (i.e. a poorer food source).

Paleolimnological Survey (ON)

◼ ‘Top-Bottom’ paleo analysis ◼ Holopedium abundance

calculated relative to all planktonic Cladocera

◼ Increases in 25 of 35 lakes

since pre-industrial times (i.e. prior to onset of acid deposition)

◼ Similar patterns in other lake

regions (e.g. Nova Scotia)

Holopedium is increasing since the 1800s

Jellification

The list keeps getting bigger.......

Multiple stressors

Road salt – sodium chloride

7 million tonnes applied to roads and parking lots each winter in Canada

(part of Robin Valleau PhD thesis research)

Chloride concentration is is in increasing in in fr freshwater la lakes and streams

Standardized [Cl-]

North American lakes

Dugan et al. 2017 Also see Winter et al. 2011 Chloride (mg/L)

Year

Lake Simcoe

Should we be concerned about salt?

• Cost to infrastructure
• Corrosion of infrastructure, vehicles and damage to

vegetation, household items ~4.8 billion/year

• Ecological impacts
• Loss of sensitive species, with small invertebrates most

effected

• Loss of ecosystem services
• Increased algal production
• Drinking water

Chloride in Ontario’s recreational lakes

82

Broadscale Monitoring Program Lake Partner Program

83

Chronic exposure: 120 mg Cl-/L Acute exposure: 640 mg Cl-/L

Is Is aquatic li life threatened?

Canadian water quality guidelines for the protection of aquatic life

The Muskoka River Watershed

• ~120 km by 60km

– Covering 4660 km2

• ~12% freshwater with more

than 2000 lakes

• Tourism in the regions

largest economy

– ~ 2 million visitor-days per year – ~ $400 million dollars in revenue – 1000s of tourism-related jobs

84

Tooke Lake (46 mg/L) Penfold Lake (45 mg/L) Wolfkin Lake (38 mg/L) Ada Lake (33 mg/L) Low High Chloride Concentration Heney Lake * (1 mg/L) Jevins Lake (91 mg/L)

85

(part of Robin Valleau PhD thesis research)

Jevins Lake

86

2 4 6 8 10 12 14 16 18 20 22 24 26 28 20 40 60 80

Bosmina spp.

20

• C. brevilabris
• A. harpae
• A. affinis

Eurycercus spp. Alonella excisa

• A. circumfimbriata
• A. intermedia
• A. costata
• A. quadrangularis

Acantholeberis curvirostris Disparalona acutirostris

• 3.0
• 2.0
• 1.0

0.0 1.0

PCA1 (0.53)

• 2.0
• 1.0

0.0 1.0 2.0

PCA2 (0.18)

1540 1560 1580 1600 1620 1640 1660 1680 1700 1720 1740 1760 1780 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000

210Pb date (A.D)

Cladocera relative abundance (%) Z-max 3 m Secchi * 1.9 m TP * 12.7 µg/L Chloride 90.9 mg/L * Secchi and TP 10-year average Sample scores

Jevins Lake Cladocera

87

Depth

20 40 Achnanthes minutissima 20 Fragilaria construens var. pumila 20 Fragilaria exigua Fragilaria pinnata Cocconeis placentula v euglypta Brachysira vitrea Nitzschia palea 20 40 Aulacoseira ambigua Asterionella formosa Fragilaria lata 20 40 Aulacoseira (nygaardii, lirata perglabra complex) 20 Aulacoseira crassipuncta 20 Aulacoseira tenella Stauroneis phoenicenteron Pinnularia COMPLEX 20 All other taxa (70)

Total sum of squares CONISS

1660 1680 1700 1720 1740 1760 1780 1800 1820 1840 1860 1880 1900 1920 1940 1960 1980 2000

Diatom relative abundance (%)

Jevins Lake Diatoms

88

Z-max 3 m Secchi * 1.9 m TP * 12.7 µg/L Chloride 90.9 mg/L * Secchi and TP 10-year average

Is it Road Salt?

Heney Lake

• Muskoka, Ontario
• Monitored long term by the

District of Muskoka and the MOECC

• Similar physical and

chemical characteristic

• Size, depth,

Calcium, TP

Heney Jevins Area (km2) 0.22 0.36 Depth (m) 5.8 3 Chloride (mg/L) 0.94 90.9

89

Heney Lake Cladocera

Bosmina sp. Acroperus harpae Alona affinis Alona quadrangularis Alona guttata Alona rectangula Alona intermedia Alona rustica Alonella excisa Chydorus sphaericus

Chydorus bicornutus Disparalona acutirustris Paralona pigra Sida crystallina Latona setifera Holopedium gibberum Ophryoxus gracilis Acantholebris curvirostris Polyphemus pediculus Eurycercus sp. Pleuroxus sp. Rynchotalona falcata

• 3.0 -2.0 -1.0 0.0

PCA1

90

Lakes Through a Gradient…

Low High Chloride Concentration Tooke Lake (46 mg/L) Penfold Lake (45 mg/L) Wolfkin Lake (38 mg/L) Ada Lake (33 mg/L) Heney Lake* (1 mg/L) Jevins Lake (91 mg/L)

91

Key Points

• Jevins Lake shows changes in zooplankton

assemblages that coincide with known road salt application

– The nature and timing of diatom assemblage changes corroborate the changes observed in zooplankton.

• Current Canadian Cl- guidelines may not be

sufficient for the protection of aquatic life

92

We Have Opened Pandora’s Box

John William Waterhouse Pandora, 1896

Lessons From The Past

2) We tend to be overly optimistic – things are generally worse and more complicated than we initially imagined. 1) The recurring patterns of “unintended consequences”.

HOURS DAYS SEASONS YEARS DECADES CENTURIES MILLENNIA

From : Smol (2008) Pollution of lakes and rivers: A paleoenvironmental perspective. 2nd ed. Blackwell Publ., Oxford.

The past matters