Water Quality Survey of Honey Harbour, 2014

Transcription

1 Water Quality Survey of Honey Harbour, 2014 Oct Progress Report to the Township of Georgian Bay Water Quality Executive Committee Long-term Questions for Honey Harbour monitoring program What is changing? Are temperature and bottom water oxygen conditions changing in North Bay? South Bay? Are trophic conditions changing in the Honey Harbour area? Are algae growing in the water column that are of concern? Why? What is causing oxygen minima in North Bay? Is there an accumulation of nutrients and metals in the bottom waters of North Bay? South Bay? Where does the phosphorus go between fall and the following spring? 1

2 Monitoring Methods Biweekly sampling done during the ice free period Muskoka District/MOE SSEA Sampling done every 2 weeks from late April/May-Nov Water collected for nutrient and algal community analysis Zooplankton collected for community analysis Temperature, conductivity, dissolved oxygen and ph taken at 1m depth intervals; Secchi depth taken Phytoplankton Pigment Profiles In 2014, Fluoroprobe used to determine vertical distribution of algal pigment concentrations at NB and SB Probe distinguishes between blue-green algae (cyanophyte), green algae (chlorophyte+ euglenophyte), red algae (cryptophyte), brown algae (diatoms+dinoflagellates+chrysophytes), and measures total chlorophyll a and yellow substances (dissolved organic carbon) Discrete samples also taken at various depths Analyzed for total phosphorus and chlorophyll a (for comparison to fluoroprobe chlorophyll a) Phytoplankton counts done on discrete samples (ID of all species, biovolume for most abundant taxa) 2

3 Max. depth is 20 m Bathtub-like Upper North Bay vs Saucer-like South Bay Max. depth is 11 m 3

4 Factors Contributing to Low Oxygen Dissolved Oxygen Temperature Epilimnion Metalimnion/Thermocline Depth Hypolimnion -cold water has highest density, max. at ~ 4ºC ~4 o C Thermocline: zone of temperature change of >1 o C/m that creates a barrier to vertical mixing Stratification leads to density differences that prevent mixing of surface and bottom waters High volume to surface area ratio leads to larger oxygen consuming zone in the bottom waters After Blumenshine Productive zone vs Consumptive zone (2 X SDV) (net DO loss) Upper North Bay (surface area:volume = 0.2) 1.8 M m³ 1.7 M m³ ~1:1 South Bay (surface area:volume = 0.3) 3.3 M m³ 1.2 M m³ ~1:2.75 4

5 North Bay Seasonal Temperature and Dissolved Oxygen Profiles Temperature North Bay Temperature and Oxygen (May 6-Oct 7, 2014) Dissolved Oxygen Thermocline was thicker in 2014 compared to previous years Dissolved oxygen in the bottom waters was not as low in 2014; no rotten egg smell Metalimnetic low was comparable to

6 South Bay Seasonal Temperature and Dissolved Oxygen Profiles Temperature Dissolved Oxygen South Bay Temperature and Oxygen (May 6-Oct 7, 2014) Surface water temperatures were lower compared to 2013 Thicker metalimnion in 2014 compared to past years, top was shallower Low oxygen zone extended further up into the water column in 2014, but didn t begin as early in the season compared to past years Rotten egg smell began in late July 6

7 Early Spring Late Summer Year-to-year Temperature Variation in NB Spring profiles vary from year to year more than late summer profiles 2014 spring temperature in upper to mid water column were lowest on record By late summer 2014, temperatures were average in the upper waters, low in bottom waters Trends in NB Bottom Water Temperature Hypolimnion temperature in late summer determined by spring temperature before stratification Temperature increases by a consistent amount (slope nearly 1) from spring to summer no matter what the starting temperature in the spring 7

8 Trends in SB Bottom Water Temperature Hypolimnion temperature in late summer much warmer than spring temperature before stratification No correlation between early spring and late summer temperature Reflects less thermal stability in SB compared to NB Spatial Variation in Temp. & DO in NB 8

9 Spatial Variation in Temp. & DO in NB Trends in Bottom Water Oxygen & Temp. Data for NB from shows variation, but no trend in late summer bottom water oxygen concentration or temperature (volume-weighted, hypolimnetic values) VWH oxygen ranges from mg/l Temperature ranges from C No correlation between VWH oxygen and temperature Hypolimnion 9

10 NB Bottom Temp, DO & TP for More data pending! SB Bottom Temp, DO & TP for More data pending! 10

11 Annual TP, Clarity, Chl a & TN in Honey Harbour * *2014 Secchi depth visibility included for NB and SB Annual Phytoplankton Open Water 1998 is P4 data, all other years are M5 11

12 Seasonal Phytoplankton NB & M5, 2013 Bloom Occurrences (>50% dominance of a single species by biovolume): NB: Chrysospharella brevispina (Jul 23) M5: Peridiniopsis elpatiewskyi (Oct 29) Blue Green Algae in North Bay Much lower biovolume than South Bay (max. <4 ug/l) Only once made up close to 50% of total pigment concentrations Average max. was 18% of total pigment concentration 12

13 Blue Green Algae in South Bay Peaks in biovolume occurred in Jul and Aug, deep in the water column, between 6-8m Max. concentration was 43.4 ug/l Average water column cyano max. % between Jul 15-Oct 7 is 72% of total pigment concentration Discrete samples taken at peaks for identification Chysosphaerella spp: % of Total Biovolume in North Bay, C. brevispina C. longispina 13

14 North Bay Temperature, Dissolved Oxygen, Total Chlorophyll a and Chrysosphaerella Bloom Timing 0 Jun Jun Jun Depth (m) Concentration (ug/l) Concentration (ug/l) Concentration (ug/l) North Bay Temperature, Dissolved Oxygen and Fluoroprobe Total Chlorophyll a in

15 Long Term Trends in Trophic Status (up to 2013) [TP] [TN] Water Clarity* Chl a Algae Bottom DO N Bay S Bay Honey Harbour SS M5 (insuff. data) *water clarity trends current to 2014 for NB and SB Summary 2014 spring bottom water temperature at NB was coldest to date No trend in long term bottom water oxygen at NB TP accumulates in narrow zone above the lake bottom at NB and SB beginning in mid-summer Trends in nutrient chemistry has shown quality has remained stable at all three Honey Harbour sites, although clarity has decreased at NB, SB and HH Blue-green algae bloom at bottom of SB lasted from beginning of July to end of August in 2014 Peridinium wisconsinense and Chrysosphaeralla brevispina continue to bloom at specific depths for short periods over the season at NB 15

16 Plans for 2015 Continue regular monitoring at NB, SB HH and M5 (profiles, chem, phyto, zoo) Fluoroprobe at NB and SB Continue discrete algae sampling at NB and SB to track distribution of specific species Filtering of metals in NB and SB (iron in particular) Acknowledgements Funding support from the Township of Georgian Bay, SSEA Ontario Ministry of the Environment (COA funding, lab analysis, use of data, technical advice, equipment loan) District of Muskoka (use of historical data) 16