Data collection and processing will include:
- Primary Productivity sampling using C-14 to determine photosynthesis rates through the water column (every week)
- Zooplankton collection using a Schindler Trap and settling of zooplankton (every week).
- Collection of Atmospheric Deposition (every week).
- Collection of lake water using a Van Dorn sampler and filtering for Chl-a (every week)
- Collection of lake water using a Van Dorn sampler, for total nutrients (Phosphorus) and filtering for dissolved nutrients (N,P,Organic C, C/N in seston for stable isotope analysis). These samples will be prepared at Castle lake for analysis in Reno (every week).
- Collection of lake water using a Van Dorn sampler and prepping for Dissolved Inorganic C (CO2) (weekly)
- Physical measurements through the water column (light, dissolved oxygen, temperature, pH, secchi depth) (every week)
- All of the above sampling will be repeated monthly for Cliff Lake (another small cirque lake nearby)
- Bioassay with N, P, N+P, Control (4-day incubation period then filtering for Chl-a)
- Chl-a analysis of samples using fluorometer (every week)
- Fish sampling. This includes setting gill nets in the evening and picking them up the next day and processing fish (measure/weigh them, take a Stable Isotope tissue sample, preserve stomach contents for later analysis)
- Collecting runoff around lake (including springs)
- Take flow measurements from outflow and springs
- Sample the benthic invertebrate community at Castle Lake (dredge sampling of sediments)
- Collection of emerging insects from lake surface, and insects falling into lake
It was gibberish to me back then, and I've learned it in a disjointed manner, but I've asked a lot of questions, and I feel pretty solid about the techniques and science coming out of the season. Here is my summer work in layman's terms.
The sampling at Castle Lake focused around two questions: 1) How productive is this ecosystem? 2) Which way and in what quantities do nutrients flow in this ecosystem?
To answer the first question, we tried to determine photosynthesis rates (what we call PPR). Since photosynthesis doesn't happen without light and since it gets darker the deeper you go in the lake, we sampled along the entire water column. We first lowered a Van Doren to trap water from each depth.
The water contains algae and bacteria that we can't see. They are the ones carrying out photosynthesis and make up the first rung of the food chains. How productive they are determines how productive the entire lake can be, so it makes sense to focus our research there.
We filled three bottles with lake water -- one "dark" bottle (well, it's white, but completely taped up so no light gets to the water) and two "light" bottles (clear). We injected all three bottles with radioactive C-14, which is easily traced. If you remember your middle and high school science, you'll recall that the photosynthesis reaction is:
sunlight + carbon dioxide + water --> glucose sugar + oxygen
To radioactive C-14 makes up the carbon in carbon dioxide. The amount of C-14 that is used up in the light bottles compared with the dark bottles - no sunlight means no reaction - should tell us the amount of photosynthesis that is happening.
To get a rate, we incubated the bottles at their various depths for exactly four hours. To make sure no extra photosynthesis went on, we had to do all the filling and injecting of the bottles in the dark. In the field where there is no light switch or sealed rooms, that means under a tarp. It got quite stuffy and hot in the sun and would billow like a parachute in the wind.
The sampling at Castle Lake focused around two questions: 1) How productive is this ecosystem? 2) Which way and in what quantities do nutrients flow in this ecosystem?
To answer the first question, we tried to determine photosynthesis rates (what we call PPR). Since photosynthesis doesn't happen without light and since it gets darker the deeper you go in the lake, we sampled along the entire water column. We first lowered a Van Doren to trap water from each depth.
The water contains algae and bacteria that we can't see. They are the ones carrying out photosynthesis and make up the first rung of the food chains. How productive they are determines how productive the entire lake can be, so it makes sense to focus our research there.
We filled three bottles with lake water -- one "dark" bottle (well, it's white, but completely taped up so no light gets to the water) and two "light" bottles (clear). We injected all three bottles with radioactive C-14, which is easily traced. If you remember your middle and high school science, you'll recall that the photosynthesis reaction is:
sunlight + carbon dioxide + water --> glucose sugar + oxygen
To radioactive C-14 makes up the carbon in carbon dioxide. The amount of C-14 that is used up in the light bottles compared with the dark bottles - no sunlight means no reaction - should tell us the amount of photosynthesis that is happening.
To get a rate, we incubated the bottles at their various depths for exactly four hours. To make sure no extra photosynthesis went on, we had to do all the filling and injecting of the bottles in the dark. In the field where there is no light switch or sealed rooms, that means under a tarp. It got quite stuffy and hot in the sun and would billow like a parachute in the wind.
For photosynthesis to occur, there needs to be chlorophyll in cells. Thus, the other way that we studied primary productivity was by filtering out chlorophyll from lake water at different depths.
Later on, we extracted the cholorphyll with methanol (a carcinogen) and ran it through a fluorometer to get amounts. The more chlorophyll, the more productive that layer of water.
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