Predicting algal bloom dynamics in a changing climate

Transcription

1 Predicting algal bloom dynamics in a changing climate Predicting algal bloom dynamics in a changing climate R.J. Sorichetti, S. Sharma, A.M. Paterson, J.A. Rusak, H. Yao York University and Ontario Ministry of the Environment and Climate Change rsoriche@yorku.ca R.J. Sorichetti, S. Sharma, A.M. Paterson, J.A. Rusak, H. Yao York University and Ontario Ministry of the Environment and Climate Change rsoriche@yorku.ca

2 Benthic Algae Attached Pelagic Phytoplankton Free-Floating Chrysophytes Diatoms fmp.conncoll.edu Cyanobacteria Chlorophytes microbewiki.kenyon.edu protist.i.hosei.ac.jp Cryptophytes Dinoflagellates Euglena tolweb.org

3 Aquatic Ecosystem Trophic Food Web

4 Increased occurrence of algal blooms Previous: large basins, eutrophic systems (Downing et al., 2001) Recent: small basins, oligotrophic systems (Carey et al., 2008) Increased occurrence over last decade in: o Laurentian Great Lakes Basin (Brittain et al., 2000; Molot et al., 2010; Watson et al., 2004; Winter et al., 2011) o Globally (Berger et al., 2008; Figueredo et al., 2007) No longer strictly associated with eutrophication Gordon Campbell, Dean Lake Concerned citizen, Twin Lakes

5 Ecosystem health implications Bloom forming o Cyanotoxins, noxious (T&O) compounds Microcystin (MC), anatoxin, saxitoxin, nodularin, 2-MIB, geosmin Laurentian Great Lakes Basin o Microcystis spp. MC (Hotto et al., 2007) Gordon Campbell, Dean Lake

6 Chemical determinants of algae Phosphorus Schindler, Downing Nitrogen Paerl, Bergström, Herrero N:P Smith, Havens Iron (Fe) Trick, Molot, Wilhelm o Photosynthesis, Chl-α synthesis, N-fixation o Organic ligands (catecholate and hydroxamate) Climate is changing

7 Increasing blooms in Ontario No. algal bloom reports 50 other golden-brown algae 40 green algae blue-green algae (Winter et al., 2011; Updated by OMOECC Algae Laboratory, Toronto, Canada)

8 Blooms increases in all parts of the Province (Winter et al., 2011; Updated by OMOECC Algae Laboratory, Toronto, Canada)

9 Blooms occurring later in the year Last day of the year blooms reported 340 December (Winter et al., 2011; Updated by OMOECC Algae Laboratory, Toronto, Canada)

10 Active community involvement 10

11 Revisit climate algal dynamics relationship Common questions asked in 20 th and 21 st century: Where do we see blooms and why? Can we identify lakes with highest bloom risk? Which algal groups bloom where? Why do algae produce bioactive compounds? What are the human and ecosystem health implications? Can blooming lakes be remediated or recovered? Will answers to these questions support new effective legislation?

12 Framing a context for algal blooms in lakes Linkages between algal blooms and climate change Lake physical and chemical attributes not one size fits all! Climate Need for a lake typology Physical basis for investigation Physical Structure Temperature Thermocline Wind patterns Mixing regime Chemical Structure Nutrients Oxygen Trophic status Biological Structure Algae Fish Microbial loop

13 A lake typology from first principles Phytoplankton Group Vertical Distribution Common Bloom Season Diatoms Epilimnion Metalimnion (cool, dense) Spring and fall mixis Chrysophytes Epilimnion Metalimnion (some motile) End of spring, early summer Cyanobacteria Epilimnion Metalimnion (some motile) End of summer Greens Epilimnion (some motile) Early summer Browns Epilimnion Metalimnion (some motile) End of spring, early summer Lake Type Greatest Response to Climate Change Response Season(s) Deep Stratified Later fall mixis, higher internal loading Fall Shallow Non-Stratified Increased lake water temperatures Summer High DOC Reduced/warmer epilimnion, cooler at depths Summer Low DOC Increased lake water temperatures and stability Summer and Fall How will lake typology help identify the lakes most at-risk from the effects of climate change on algal dynamics?

14 York University and OMOECC partnership Dr. Sapna Sharma York U Dr. Andrew Paterson OMOECC Dr. Jim Rusak OMOECC Dr. Huaxia Yao OMOECC Thomas Van Zuiden York U Research Questions: 1. What are the linkages between algal blooms and climate change? 2. Which lakes are at highest risk for algal blooms under climate change scenarios?

15 Modeling algal dynamics in a changing climate (Van Zuiden et al., 2016) LTER site data across Ontario (ELA, Algoma, Muskoka, Algonquin) Lake physical parameters, water chemistry, biology (algal group biomass), meteorological and climate data Identify lake characteristics at highest risk of algal blooms Predict future algal dynamics in lakes in 2050 and 2070 under 126 scenarios of climate change: Present

16 DESC inland waters monitoring program 9 lakes (monthly to bi-weekly) 1981-present 25 streams (weekly; 14 gauged) 4 climate stations (automatic, real-time) 2 lake buoys (automatic, real-time) climate station lake buoy

17 Relative Biomass (z-scores) Algal trends in Dorset A lakes = No change = Increasing biomass = Decreasing biomass Plastic Lake Dinoflagellate Biomass Year

18 Group-level changes in relative biomass Increasing chrysophytes Decreasing diatoms Decreasing chrysophytes Increasing diatoms

19 Warmer and longer Ontario summers in 2070 Temperature (C) Mean summer temp increase Later ice-on Earlier ice-off Earlier stratification onset Later fall mixis temp RCP 2.6 RCP 4.5 RCP 6.0 RCP 8.5 Climate Change Scenario (S. Sharma Unpubl. Data, 2016) (Crossman et al., 2016)

20 Climate change has affected thermal properties of Dorset lakes Lake warming driven by increased autumn air temperature Decreasing mixing depths (climate-driven increases in lake DOC) Delayed autumn mixing Synchronous changes among lakes points to regional driver (climate?) How has changing lake physics influenced algal dynamics?

21 Summary Climate and algal dynamics are changing Climate lake physical structure (temperature/mixing) lake chemistry and biology Must first understand how climate affects lake physics and in turn, biology (algal dynamics) Understanding effects of climate change = national water strategy Thank you!