limnology lecture 7 - university of...
TRANSCRIPT
![Page 1: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/1.jpg)
Light and oxygen in lakes
Limnology
Lecture 7
![Page 2: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/2.jpg)
Outline
• Light
• Diffusion
• Oxygen gradients
![Page 3: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/3.jpg)
Vertical Gradients in Lakes Properties of
Water Properties of Lake
Basins
Vertical Gradients •Light
•Heat
•Dissolved gases
•Dissolved nutrients
![Page 4: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/4.jpg)
Light and Water
• Reflection
• Absorption
C6H12O6
![Page 5: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/5.jpg)
Light and Water
• Reflection – Surface
– Scatter
• Absorption – Heat
– Potential Energy • Stored in chemical bonds
via Photosynthesis
C6H12O6
![Page 6: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/6.jpg)
Attenuation equation Iz = I0 e - kz where e = natural logarithm k = attenuation coefficient characteristic for each water body and each wavelength K = Kwater + Kdissolved organics + K particulates
Light and Water
![Page 7: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/7.jpg)
Light Gradients in Water
Kdissolved organics – humic acids absorb short wavelengths (blue, UV)
![Page 8: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/8.jpg)
Dunham Pond
![Page 9: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/9.jpg)
Dunham Pond
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 50 100
Dep
th (m
)
Percent Surface Light
y = -3.4936x + 4.198 R² = 0.9819
-3
-2
-1
0
1
2
3
4
5
0 0.5 1 1.5 2
ln P
erce
nt L
ight
Depth
![Page 10: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/10.jpg)
Why is deep water blue?
Kwater – pure water absorbs long wavelengths Blue absorbed the least, scattered the most
![Page 11: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/11.jpg)
Water decreases light and changes colors
Kwater – pure water absorbs long low energy wavelengths
![Page 12: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/12.jpg)
Solar Radiation as a Spectrum Electromagnetic Spectrum
![Page 13: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/13.jpg)
Light Gradients and aquatic coloration
photic
twilight
![Page 14: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/14.jpg)
![Page 15: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/15.jpg)
Light and habitat
Secchi disk ~ 10% of surface light Photic zone – light is > 1% of surface value
![Page 16: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/16.jpg)
Light Gradients in Water
Lake k Secchi Depth Euphotic Crater Lake (OR) 0.06—0.12 25— 45 >120 Lake Baikal 0.2 5— 40 15—75 Lake Erie 0.2 — 1.2 2—10 12—26 Dunham Pond 3.5 ? ?
![Page 17: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/17.jpg)
Dunham Pond
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0 50 100
Dep
th (m
)
Percent Surface Light
y = -3.4936x + 4.198 R² = 0.9819
-3
-2
-1
0
1
2
3
4
5
0 0.5 1 1.5 2
ln P
erce
nt L
ight
Depth
![Page 18: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/18.jpg)
Light and habitat
![Page 19: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/19.jpg)
Light and habitat
Limnetic
Compensation depth – where photosynthesis = respiration in plants Littoral – From shore to aphotic zone - emergent and benthic plants Limnetic – aphotic zone on benthos
![Page 20: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/20.jpg)
Light Gradients in Water
Pelagic – open water in limnetic zone Compensation depth – where net photosynthesis = 0 photosynthetic production = respiration photic or euphotic/aphotic
![Page 21: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/21.jpg)
Light Gradients in Water
![Page 22: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/22.jpg)
Oxygen and temperature
![Page 23: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/23.jpg)
Diffusion Equilibrium
Henry’s Law:
Cs = KH Pt
Cs = amount of gas dissolved
KH = solubility coefficient for a given temperature
Pt = partial pressure of gas in atmosphere
![Page 24: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/24.jpg)
Oxygen in water
Diffusion from atmosphere O2 partial pressure = 0.203 atm KH (20C) = 1.39 mmol O2/kg H2O x atm Cs = KH Pt O2 (20C) = 1.39 * 0.20 = 0.28 mmol/kg = 9.03 mg/L
![Page 25: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/25.jpg)
Oxygen and species survival
Species DO limit (mg/L) Trout 7-8 Bass 5 Sunfish 4.7 Carp 4 Amphibian larvae 1-2 Amphipods 2 Chironomids 1 Worms 0.7
Mattson et el. 2007
![Page 26: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/26.jpg)
Oxygen Gradients in Dimictic Lake
From: Wetzel 1975
Biological oxygen demand -Rate of oxygen uptake by aquatic organisms
Orthograde
Clinograde
![Page 27: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/27.jpg)
Thermocline effects
O2
Nutrients
![Page 28: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/28.jpg)
Dunham oxygen
![Page 29: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/29.jpg)
Oxygen Gradients in Dimictic Lake
Positive heterograde
Algae sit on density “shelf” More nutrients
Negative heterograde
Respiration of algae, zoop, decomposition of detritus rain on “shelf”
![Page 30: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/30.jpg)
Muskoka Lake, Ontario, ILEC
![Page 31: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/31.jpg)
Fish Kills (low O2)
Occur often in small ponds in winter under ice cover – why?
![Page 32: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/32.jpg)
Greenbank 1945
![Page 33: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/33.jpg)
Also occur often in large lakes in late summer – why?
Fish Kills (low O2)
![Page 34: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/34.jpg)
Muskoka Lake, Ontario, ILEC
Late summer
![Page 35: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/35.jpg)
Also occur most often at dawn – why?
Fish Kills (low O2)
![Page 36: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/36.jpg)
Eutrophic Timber Ridge Pond in OK, Freimuth and Bass 1994
At dawn
![Page 37: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/37.jpg)
Also occur often after summer storm – why?
Fish Kills (low O2)
![Page 38: Limnology Lecture 7 - University of Connecticuthydrodictyon.eeb.uconn.edu/.../5c/Lecture_7_-_Light... · Lecture 7 . Outline •ight L • Diffusion • Oxygen gradients . Vertical](https://reader033.vdocuments.us/reader033/viewer/2022051910/5ffec0bdad6bfe59bb5a4cfb/html5/thumbnails/38.jpg)
Yount, 1961
Storm disruption of stratification