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A synopsis of the Great Lakes Near shore Initiative attached algae program David Depew, Veronique Hiriart Baer Watershed Hydrology and Ecology Research Division Environment Canada October 30 2013, Lake Erie Millennium Network Meeting

SLIDE 1

A synopsis of the Great Lakes Near shore Initiative attached algae program

David Depew, Veronique Hiriart‐Baer Watershed Hydrology and Ecology Research Division Environment Canada October 30 2013, Lake Erie Millennium Network Meeting

SLIDE 2

DRAFT – Page 2 – December 3, 2013

Background

1970s 1980s 1990s 2000s Present

Implementation of GLWQA, beginning of point source P control
Dreissenid mussels invade L. Erie, P loads continue to decline
Blooms of Cladophora recur along north shore of E. L. Erie
Revival of Cladophora related research in E. L. Erie and elsewhere

SLIDE 3

DRAFT – Page 3 – December 3, 2013

Background

Rock Pt. Prov. Pk. 2006 Image: S Higgins Rathfon Pt. July 2013 Volume of algal material collected on Intake screens: OPG Pickering.

SLIDE 4

DRAFT – Page 4 – December 3, 2013

Soluble Reactive P levels (2 – 10 m)

Apr – May 2005 July – Aug 2005 MDL = 0.35 µg L-1

SLIDE 5

DRAFT – Page 5 – December 3, 2013

Present Status…

Benthic algal blooms continue to impair near shore

water quality, habitat and recreational uses.

Near shore P levels not indicative of excessive

nutrient loading.

Temporal trends not easy to identify.
Elucidation of causal factors has proven

challenging, but evidence to‐date supports the role

f dreissenid mussels as key agents of change.

SLIDE 6

DRAFT – Page 6 – December 3, 2013

Key Question

What, if any nutrient target(s) may provide reasonable protection of near shore regions from recurrent blooms of benthic algae?

SLIDE 7

DRAFT – Page 7 – December 3, 2013

GLNI attached algae program objectives

Identify proximate sources of P contributing to

nuisance blooms

Quantify P processes in and above dreissenid beds

in Eastern Lake Erie (R. Smith, J. Majarreis, U Waterloo)

Reconstruct historical timeline of benthic algal

resurgence in E. Lake Erie (K. Mueller, U Waterloo)

SLIDE 8

DRAFT – Page 8 – December 3, 2013

Study Area

SLIDE 9

DRAFT – Page 9 – December 3, 2013

Approach

δ18OPO4 to delineate P sources responsible for

Cladophora blooms

– SRP – Cladophora tissue – Dreissenid tissue – Dreissenid “wastes”

Use of other isotope based tracers (e.g., DOC13,

15N18O3) to constrain sources

Standard physical and chemical water quality

metrics with quantitative benthic survey data

SLIDE 10

DRAFT – Page 10 – December 3, 2013

δ18O – PO4 Primer

P O O O O = O18 = O16 H O H P O O O O H O H H O H H O H H O H H O H Enzyme mediated O exchange drives δ18O-PO4 to equilibrium based on temperature

SLIDE 11

DRAFT – Page 11 – December 3, 2013

δ18O – PO4 of different P sources

δ18OP of potential P sources

7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 Chemical fertilizers Detergents Semi processed P ores Aerosols WWTP effluent Fecal leachate

(Data from Young et al. 2009)

Do different P sources have different δ18O – PO4 ?

SLIDE 12

DRAFT – Page 12 – December 3, 2013

δ18O – PO4 in different freshwaters

Isotopic disequilibrium
bserved in freshwaters

to date

Biological processing of

P does not completely eliminate source signatures in freshwaters

Indication of at least 2

distinct sources in C and W basin L. Erie

(Data: McLaughlin et al. 2006a,b, Elsbury et al. 2009, Young et al. 2009)

δ18O - PO4

8 10 12 14 16 18

δ18Ο− PO4 offset from equilibrium

2 4 6 Lake Tahoe Tributaries Lake Erie Tributaries SJR Tributaries SJR mainstem

Does rapid P cycling overprint source signature too quickly?

SLIDE 13

DRAFT – Page 13 – December 3, 2013

Progress to date

Cons

– Low SRP (< 1 µg L‐1) requires large volumes of lake water (> 100 L) – Organic matter contamination – Long sample processing time

Pros

– Suitable optimization of purification protocol for low SRP waters is close – Good recovery of free phosphate from Cladophora tissues without structural P components (e.g., hydrolyzed biological molecules) – does this reflect “recent” P sources?

SLIDE 14

DRAFT – Page 14 – December 3, 2013

Future outlook

Cautious optimism – little good data for low P freshwater

systems

More samples – help to constrain the range of variability

expected in δ18O – PO4 in lake waters, Cladophora tissues and dreissenid wastes

Need a better grasp of fractionation effects induced by

A synopsis of the Great Lakes Near shore Initiative attached algae program

David Depew, Veronique Hiriart‐Baer Watershed Hydrology and Ecology Research Division Environment Canada October 30 2013, Lake Erie Millennium Network Meeting

Background

1970s 1980s 1990s 2000s Present

Background

Rock Pt. Prov. Pk. 2006 Image: S Higgins Rathfon Pt. July 2013 Volume of algal material collected on Intake screens: OPG Pickering.

Soluble Reactive P levels (2 – 10 m)

Apr – May 2005 July – Aug 2005 MDL = 0.35 µg L-1

Present Status…

water quality, habitat and recreational uses.

nutrient loading.

challenging, but evidence to‐date supports the role

Key Question

What, if any nutrient target(s) may provide reasonable protection of near shore regions from recurrent blooms of benthic algae?

GLNI attached algae program objectives

nuisance blooms

in Eastern Lake Erie (R. Smith, J. Majarreis, U Waterloo)

resurgence in E. Lake Erie (K. Mueller, U Waterloo)

Study Area

Approach

Cladophora blooms

– SRP – Cladophora tissue – Dreissenid tissue – Dreissenid “wastes”

15N18O3) to constrain sources

metrics with quantitative benthic survey data

δ18O – PO4 Primer

P O O O O = O18 = O16 H O H P O O O O H O H H O H H O H H O H H O H Enzyme mediated O exchange drives δ18O-PO4 to equilibrium based on temperature

δ18O – PO4 of different P sources

(Data from Young et al. 2009)

Do different P sources have different δ18O – PO4 ?

δ18O – PO4 in different freshwaters

to date

P does not completely eliminate source signatures in freshwaters

distinct sources in C and W basin L. Erie

Does rapid P cycling overprint source signature too quickly?

Progress to date

– Low SRP (< 1 µg L‐1) requires large volumes of lake water (> 100 L) – Organic matter contamination – Long sample processing time

– Suitable optimization of purification protocol for low SRP waters is close – Good recovery of free phosphate from Cladophora tissues without structural P components (e.g., hydrolyzed biological molecules) – does this reflect “recent” P sources?

Future outlook

systems

expected in δ18O – PO4 in lake waters, Cladophora tissues and dreissenid wastes

extra‐cellular enzymes and digestive processes