3/7/2016 Investigating golden brown benthic algae in Torch Lake Presented to Leelanau Clean Water group Dean Branson, Becky Norris, Trish Narwold February 18, 2016 Torch. Clam, & Bellaire Lakes www.3lakes.com Collaborative Investigation with internationally recognized diatom experts • Dr. R. Jan Stevenson, MSU‐Zoology Dept. • Dr. Rex Lowe, U of M‐Biological Res. Station • Dr. Pat Kociolek, U of M‐Biological Res. Station • Three Lakes Association grant funds and volunteers to collect samples of groundwater and benthic algae; some funds from TLPA 1 3/7/2016 What is it? What’s causing it? What can be done to prevent it? Patterns of golden brown benthic algae, changing the aesthetic appearance of the lake from beautiful turquoise to plain brown! Patterns of areas with and without golden brown benthic algae, west side of Torch Lake 2 3/7/2016 Underwater photo of golden brown benthic algae in Torch Lake Initial Research Strategy Compare two sites: Low density land use High density land use , . Camp Hayo‐Went‐Ha Petty property, August 2015 3 3/7/2016 East Port DNR Petty 100.000 100 80 SW g/L 50.000 60 μ g/L μ 40 0.000 Well P 20 N N ‐ ‐ ‐ water Clam Dockside 0 PO4 NH4 NO3 100 PO4‐P SW GW g/L 50 μ Sand Point 0 100 g/L 50 μ 0 SW GW PO4‐PNO3‐NNH4‐N Clam River SW SW 100 GW with band g/L 50 GW w/out band μ 0 P N N ‐ ‐ Lake Ave. ‐ PO4 NH4 100 NO3 80 Alden Harbor 60 100 g/L μ 40 20 g/L 50 μ 0 0 P N N ‐ ‐ ‐ PO4 NH4 NO3 SF GW SW GW Concentrations of phosphorus Surface water vs Interstitial water 4 3/7/2016 Nutrient‐enriched agar in cylinders in Torch Lake for 20 days to determine the nutrient‐limitations of diatoms associated with golden brown benthic algae; July 2015 …. In summary • Torch Lake P+ limited • Blooms most likely caused by P input • P source from ground water influx • Different communities on treatments 5 3/7/2016 Results of Nutrient Diffusing Substrate Experiment Cell Densities P+ N+P Large pseudoanab Large aena Ulnaria Diatoms pseudoanaba Ulnaria Diatoms 1% 1% 1% ena 1% 1% Achnanthidiu 2% m Achnanthidi 25% um Others 27% 26% Others 27% Centric Other algae 7% 2% Other algae Centric 11% 19% Naviculoid Nitzschia 13% Nitzschia Naviculoid 20% 13% 3% Cell Density (Cells/cm2) of All Benthic Algae • Averaging about 500,000 cells/cm2 • Mostly diatoms • Density in sand more than rock • Density in sparse sand same as dense sand • What causes diatoms to move from the top centimeter to the surface of the sand? 6 3/7/2016 Aerial photos of Gourley beach during 2015 summer season Paul, Trish, Art, and Fred assembling a piezometer; well point, perforated ¼‐ inch tubing and fine‐ mesh screen. 7 3/7/2016 Driving a piezometer into the lake bottom Shayna, Grandpa Dean, & Becky collecting a groundwater sample from a piezometer using a Topsider multipurpose vacuum pump connected to a sample‐collection jug. 8 3/7/2016 Piezometers Near‐shore groundwater wells Professor R. Jan Stevenson and Becky Norris examining a “peeper” prior to installation 9 3/7/2016 Driving a “peeper” into the lake bottom An installed “peeper” …..sampling groundwater (two depths) and surface water using passive diffuser bags in perforated PVC pipes 10 3/7/2016 Diatom Findings • 140 Diatom species associated with golden brown benthic algae assemblages; 8 species new to science • Naturally occurring in most lakes, rather than invasive species • Epithemia, most abundant diatom taxa, capable of housing blue‐green algae, and endosymbiotic nitrogen fixation Microscopic image of Epithemia smithii identified in a sample collected at Camp Hayo‐Went‐Ha. Intriguing research questions, not yet investigated • Are groundwater nutrients inducing golden brown algae? • Are the patterns of groundwater entering the lake similar to the patterns of golden brown algae, infrared images of surface water temp ~40 deg F with rising warmer groundwater ~50 deg F ? • Do other lakes have similar diatom assemblages and groundwater profiles as the golden brown benthic algae assemblages in Torch Lake? 11 3/7/2016 Questions ? 12.