Algae in Honey Harbour

Algae in Honey Harbour

Aisha Chiandet, Water Scientist Severn Sound Environmental Association May 12, 2017

Coastal Embayments in Muskoka Area

Coastal Embayments in Muskoka Area

What Are The Issues?

• Concern from residents: – Attached algae on rocks (periphyton/biofilm) – Low water clarity, green colour

• SSEA observations: – Changing algae communities – Increased dominance by a small number of species/ genera

Periphyton growth in North Bay

What Do We Want to Know?

• Who is present? What types of algae are there and in what proportions?

• Where are they found? Vertical and horizontal distribution?

• When do they appear throughout the season?

• How are patterns changing with time?

• Why do certain species dominate over others?

• What are the implications?

Collecting pigment data using the Fluoroprobe C. brevispina

C. longispina

Algal species present in North Bay

Data Collection Methods • Biweekly sampling - ice free period (May-Oct) • Water collected - nutrient & algal community analysis • Temperature, conductivity, dissolved oxygen and pH − Taken at 1m depth intervals

• Fluoroprobe - measures concentration of algal pigments in the water column − Discrete samples taken for algae counting where peak in chlorophyll a pigment occurs

• Secchi depth - to measure water clarity • Algae count data - 1998, 2003, 2005, 2008-2016 • Fluoroprobe data - 2010-2016

Results – Who Is Present?

Seasonal biovolume averaged from 2005-2016

• • •

Based on counts (composite & discrete samples) & pigment profiles Very different dominance in NB vs SB NB – Mainly Chrysophytes (Chrysosphaerella, Synura) and Dinophytes (Peridinium); also Diatoms (Fragilaria, Cyclotella)

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SB – Mainly Blue-Greens (BGs) (Planktothrix agardhii, Aphanizomenon flos-aquae, Dolichospermum) and Chrysophytes (Synura), also Diatoms (Fragilaria)

• • • •

M5 – Mainly Diatoms (Asterionella, Fragilaria) HH – Mainly Chrysophytes (Chrysosphaerella, Dinobryon, Synura, Uroglena) Some Chrysophytes have the ability to photosynthesize and also feed on organic carbon compounds (e.g. bacteria and detritus) → mixotrophs Some BGs have the ability to regulate their buoyancy and can dominate narrow depth ranges deep in the water column

Results – Where Are They Found?

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Discrete samples collected for microscope analysis where peaks total chlorophyll a are observed using Fluoroprobe • In SB, peak between 6-8m identified as Planktothrix; peaks at ~4-6m identified as Aphanizomenon and Dolichospermum • In NB, peak at ~4m identified as Chrysosphaerella at certain times and other times identified as Peridinium (3-6m) • Depths of these taxa specific layers are consistent year after year 2014 Fluoroprobe profiles • Blitz sampling in 2014 • Multiple pigment profiles around NB/SB • Showed coherence in layers in NB, but BGs only in deep hole in SB, not near shore

North Bay

South Bay

Chrysosphaerella

Aphanizomenon/ Dolichospermum Planktothrix

Results – When Do They Appear?

• Different species peak at different times • Chrysophytes peak in early summer and again in late summer in NB • Dinophytes peak in mid-summer in NB • BGs peak in late summer-early fall in SB 2015 Fluoroprobe profiles North Bay

South Bay

Results – How Are Patterns Changing?

• Algae data available back to 1998 • Since 2009, large Chrysophyte and Dinophyte blooms in NB more frequent • Higher BG and Dinophyte biovolumes in last 3 yrs in SB • Larger amounts of Chrysophytes and Diatoms in last 5 yrs in HH • Larger amounts of Chrysophytes in last 6 yrs in SS open waters • Shifts to Chrysophyte dominance seen in other Ontario lakes • Shifts to Chrysophyte and BGs could be combination of nutrient and climatic factors

Algae biovolume in composite samples, 1998-2016

Results – Why Dominance?

• Conditions are right for BGs to bloom in NB – high iron and TP in bottom waters, strongly stratified, warm sheltered waters – but they don’t – Remains unknown why Chrysophytes dominate – May have an advantage due to mixotrophy (ability to photosynthesize and feed on organic matter)

• BGs dominate in SB, but haven’t always – New phenomenon within last 3 years – Further work need to see what conditions have changed

What Are The Implications?

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Dissolved Oxygen, 2015

Deep-water algae layers likely explain patterns of low oxygen in deep sheltered embayments like NB and SB Are algae growing that are of concern?

Need to keep an eye on some BG spp. in SB – Depth of most BG layers in SB do not correspond to where generally people swim or have water intakes (~7m) – Some layers are closer to the surface (~4m)

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BGs present in SB have the potential to produce cyanotoxins – Can cause skin and gastrointestinal irritation in humans and can be harmful to pets

• Some Chrysophytes can cause bad taste/odour in drinking water (e.g. Synura, Dinobryon)

NB, 2015

SB, 2015

Future Considerations • Increased total algal growth expected with increased temperature – Water temperature measured at long term monitoring stations across Severn Sound since 1986 – 6 of the top 10 warmest average surface water temperatures have occurred within the last 7 years

• BG blooms may become more common under warmer conditions

Thank-You! SSEA acknowledges our municipal members:

Our external funding and data sources: Ministry of Environment and Climate Change Canada-Ontario Agreement District Municipality of Muskoka

And our team: SSEA staff Don Limoges – boat captain Elaine Carney – phytoplankton taxonomist

WP Dailey © 2012

For more information please visit: www.severnsound.ca