Effects of Nitrogen Dilution

Effects of Nitrogen Dilution on Algal Growth in Lake Erie Water Samples

Nathan Arroyo Summer REU 2011

Acknowledgements Stone Lab REU

Program Dr. Bade Matt Thomas

NOAA/Ohio Sea Grant

Summer 2011 Limnology Class

Introduction Lake Erie plagued with late summer algal

blooms Thick mats of algae are unappealing hurt tourism cause fish kills toxic to animals and humans

Background

Eutrophication studied for over a century

Schindler- 1970’s Phosphorous Paradigm

Recently challenged with idea of nitrogen limitation

Questions Asked

What is the best strategy to remediate the Lake?

Can the growth of algae in Lake Erie be curbed by limiting nitrogen?

Hypothesis: By removing nitrogen, the growth of algae in Lake Erie can be reduced.

Nutrient Dilutions Samples from Gibraltar Island and Sandusky

Bay Samples diluted with artificial Lake Water

Gibraltar Island - no Ca+2 or Si+4 Sandusky Bay - no Ca+2

Nutrient Dilutions

Lake Water 100% 80% 60% 40% Artificial Water 0% 20% 40% 60%

Nutrient Dilutions Samples incubated at alligator bar for a week Algal biomass estimated from Chlorophyll a using fluorometer

Gibraltar Dilutions

0

5

10

15

20

25

30

35

Rela

tive

Gro

wth

(µg

Chl

. a/L

)

C + P

Gibraltar Dilutions

-10

0

10

20

30

40

50

1C 0.8C 0.6C 0.4C 1+P 0.8+P 0.6+P 0.4+P

Rela

tive

Gro

wth

(µg

Chl

. a/L

)

Gibraltar Dilutions

Sandusky Bay Dilutions

-35

-30

-25

-20

-15

-10

-5

0

Rela

tive

Gro

wth

(µg

chl.

a/L)

C + P Sandusky Bay Dilutions

-60

-50

-40

-30

-20

-10

0

10 1C 0.8C 0.6C 0.4C 1+P 0.8+P 0.6+P 0.4+P

Rela

tive

Gro

wth

(µg

chl.

a/L)

Sandusky Bay Dilutions

Summary

Gibraltar dilution- some limitation from nitrogen dilution, overwhelming phosphorous limitation

Sandusky Bay Dilution-slightly phosphorous limited, results point to possible other nutrient limitation (Si)

Conclusion