WINTER LIMNOLOGY FIELD DAY
 RETURN TO SYLLABUS

2019	2/9/19 Gold Lake - Profiles: Sonde & Microbes (Blackboard image, below) Separate probes for DO & pH, both with temperature (tied together).  Probe depth recorded to 7 m, but lines tangled; vs. van Dorn bottle depth ~5m DO meter calibration adjusted for 100% at surface.  Peak 104% at 1 & 1.5 m. Lake partly snow-covered (see photos) Ice thickness 29-31 cm, varying by hole Seechi disk depth = 2.9-3.0 m (~10% surface light) Datasheet (pdf, 500k) Click images to enlarge Profiles: Filters Color (i.e. phytoplankton concentrations) strongest at 3.0-meter samples Color = yellow green (green algae, cyanobacteria, and diatoms observed in microscope work) Zooplankton (copepods) all sample depths From 1 gallon through 25 micron mesh plankton net, concentrated to 250 ml - 150 ml filtered.	Click images to enlarge photos (c) T Kittel DO, pH, temperature sampling Sediment sampling for benthic arthropods Phytoplankton & invertebrate lab work
	Previous years
2018	2/3/18 Gold Lake -   Profiles: Sonde & Microbes (Blackboard image) Sonde readings only to ~0.5m of sediment surface (sonde was missing cage to protect sensors) Lake partly snow-covered (see photo above) Ice thickness 22 cm Seechi disk depth = 2.7m (~10% surface light) Datasheet (pdf, 500k) Click images to enlarge Vertical axis = depth (m) At bottom of profiles: lightly drawn lines extend profiles to near sediment surface, hypothesized from previous years' results Profiles: Filters Color (i.e. phytoplankton concentrations) strongest at 4.5 & 5.5-meter depth samples Color = brownish green (few cyanobacteria and diatoms observed in microscope work) Zooplankton (copepods) 3-5 to 5-5m, mostly at 4.5 m From 1 gallon through 25 micron mesh plankton net Phytoplankton microscope photos - (c) Alex Sandberg-Bernard Anabena - cynobacteria Staurastrum - genus of green algae, Desmid family Diatom - various species - in water at the sediment interface? Click images to enlarge	Click images to enlarge   Class on Gold Lake photo (c)S.Spaulding Following photos (c) T Kittel Ice Surface Segmenting the Sediment Core
2017	2/11/17 Gold Lake - Profiles: Sonde & Microbes (Blackboard) Vertical profile sampled in shallow water because of thin ice - max depth 1.75m Seechi depth = 1.45m.  At an additional hole, Seechi = 2.25m Ice thickness 33cm Datasheet (pdf, 800k) Cyanobacteria important throughout profile T and pH profile dotted lines below 1.75m and %DO profiles are hypothesized based on previous years' results Profiles: Filters
2016	2/6/16 Gold Lake - Profiles: Sonde & Microbes (Blackboard) % Dissolved Oxygen data from 2011 (not measured by this sonde)  -- see 2013 & 2014 results to see variation. Lake entirely snow-covered (see photo to left) Ice thickness 31-32 cm Click images to enlarge Profiles: Filters Color (i.e. phytoplankton concentrations) strongest in 2 & 4 meter depth samples Color = blue-green, corresponding to high presence of cyanobacteria observed in microscope work Zooplankton present at all 4 depths, most numerous at 4 m, followed by 2 m Filters from Left to Right are from 1, 2, 4, & 6 m depths Sample = 1 gallon reduced to 105ml; from that 40ml subsample filtered	Click images to enlarge Photos (c) Sarah Spaulding Mid-lake measurements Inspecting the hole in progress Filtering sample for plankton
2015	1/31/15 Gold Lake - 3 Mid-lake measurement sites - click to enlarge Photo: (c) T Kittel Datasheet (pdf, ) - pending Profiles: Hydrolab sonde & Microbes (Blackboard) Sonde data at 0m were measured in situ.  Other profile values were from water samples, measured in the lab a few hours later. %DO below 4m were likely <100% and came to equilibrium (~100%) by time measured in the lab. Profiles: Filters Zooplankton present in all 3 filters Note:Some sample lost during 3m filtering. Daphne - photo (c) Jake DePompolo	Click images to enlarge: Photos: (c) Sarah Spaulding Water column sampling with Van Dorn bottle Filtering phyto- & zooplankton sample Sediment sample
2014	2/09/14  Gold Lake - Ice thickness = 17" (43cm), snowcover = 10cm.  Overcast, snowing from divide, breezy (NW), air T = -1.1C. Datasheet (pdf, 2M) Profiles: Hydrolab sonde & Microbes (Blackboard) Profiles: Filters 2m - darkest yellow-green* with some zooplankton 4.5 m - dark yellow-green* with some zooplankton 6.5 m - high amount of dark brown fines = suspended detritus (*After a week, faded to blue-green) Biota: Microscope images Anabaena - cyanobacterium; with heterocyst, upper left Photo: (c) Dylan Brown Nematode - from lake sediments Photo: (c) Matt Guyerson         Phyto- and Zooplankton Profiles Photo: (c) S.Spaulding Lake Sediment Core! Photo: (c) Matt Guyerson	Click images to enlarge - Also featured on INSTAAR's website: http://instaar.colorado.edu/galleries/winter-ecology-class-field-day/ Mid-lake measurements Photo: (c) T Kittel Following Photos: (c) S.Spaulding   Hydrolab sonde profile - physical measurements
2013	2/16/13 Gold Lake - Profile composite: Blackboard+Filters (pdf, 2M) Datasheet (pdf, 2M) Ice thickness = 16" (40cm), snow-free (except small patches).  Clear sky, breezy, air T above 0C. Click images to enlarge - See also composite of physical and filter profiles (pdf)	Click images to enlarge -
2012	1/28/12 Gold Lake - Blackboard & water sample filter images - Composite of physical and biota profiles (pdf, 140k) Datasheet (pdf, 400k) Gold Lake Zooplankton - Copepods (left, center), Daphne (right) --Microphotos by Corey Slinkard (c) 2012
2011	1/29/11 Gold Lake - Blackboard & water sample filter images - Composite of physical and biota profiles (pdf, 600k) Datasheet (pdf, 200k) Summary Discussion - On the day of our visit to Gold Lake, the ice was roughly 18" thick and free of snow.   Lake temperatures were near zero under the ice, and then close to 4deg C for the rest of the column (Vertical profile of temperature = 1st curve on the right in the image below). High levels of Dissolved Oxygen (yellow chalk line, middle of image) were seen under the ice to a depth of over 3m.  This indicates significant plant (phytoplankton) production going on under the ice, in the high light environment.  Production is likely limited by nutrients shown by reduced Specific Conductivity (white line 2nd from right) in the upper waters.   We also observed highest numbers of zooplankton in the upper layer - with gravid (egg-bearing) copepods suggesting that crustacean populations are doing well grazing on the lake's phytoplankton. Below 3m, light levels drop below 1%.  At this point, plant production drops sharply and decomposition takes over as the dominant process. Nutrient release by decomposition is shown in higher Specific Conductivity (white line 2nd from right).  In spring, with ice breakup, these nutrients will be returned to the upper level of the lake, restoring nutrients for plant production. Click images to enlarge - See also composite of physical and biota profiles (pdf)	Vertical Profile measurements Photo: (c) T Kittel Zooplankton Sampling - Photo: (c) T Kittel
2010	2/2010 Gold Lake - Summary & Photos (ppt, 4.5M) Data (xlsx, 50k)
2009	2/21/09 Lily Lake -  Blackboard image of sonde profiles & biota notes (pdf, 3M) Plankton (and more) filters (jpg, 800k) - c/o Sara Fairchild
2008	2/23/08 Gold Lake -  Winter Profiles (datasheet pdf, 390k) Blackboard image - sonde profiles and biota notes (jpg, 800k, c/o David Rosengarten) Phytoplankton Filters (jpg, 580k)
2006	2/26/06 Gold Lake - Winter Profiles (xls, 20k, c/o Jyh Huang) Phytoplankton Filters (jpg, 300k)	Zooplankton Sampling - Photo: (c) T Kittel
2005	Spring '05 Gold Lake -  Winter Profiles (data: xls, 35k - plots: pdf, 190k) Phytoplankton Filters (jpg, 300k)	Drilling hole in ice for sampling Photo: (c) T Kittel

• rev.  1 Mar 19