clement phosphorus and algae...annual monitoring report. walterhouse, m. (1999). total maximum daily...

Delilah ClementGraduate Research Assistant

clemedel@mail.gvsu.edu

• Phosphorus (P) enrichment eutrophication

• Algal Blooms

• NPDES Permit Point Sources

• Agriculture is a Nonpoint Source of P

Mary Ogdahl, GVSU - AWRI

A) Soil matrix flow: slowerB) Macropore flow: faster

C) TillageD) Crops Regime

(not to scale)

Land Use Area: 45% Agri33% Urban20% Natural

1-9: Tile Drains

10: Lake Macatawa

11: Lake Michigan

(Holland Sentinel)

• Drowned river mouth

• Hyper-eutrophic

• Lake TMDL for 72% TP reduction

• 1997: 125ppb Goal 50ppb

• 2015: 98 ppb

• 91% of P from nonpoint sources

Objectives

1) Conduct a tile drain effluent sampling survey of the Macatawa Watershed

SRP: soluble reactive phosphorus TP: total phosphorus

2) Investigate the seasonal changes in tile drain P

3) Use algal bioassays to measure the bioavailability of P found within the tile drains

Methods: Timeline

2015 2016

Mar Apr May Jun July Aug Sept Oct Nov Dec Jan Feb

Tile Drain Sampling x x x x x x x x x x x x

Bioassays x x x

Sampling Site

Collect Tile Drain Effluent

Bioassay 1Selenastrum

Bioassay 2Lake Mac Inoculum

Measure SRP and TP

Measure chlorophyll-a

Measure chlorophyll-a

Record DischargeRecord Land Management Factors

Determine Algal

Community

Lake Mac Algae Selenastrum

RPM = 175Light (PAR) + Temp: based on season

Low High Mean ± SE Median

SRP (ppb) <5 447 93 ± 11 64

TP (ppb) 10 560 136 ± 13 102

%SRP 0% 89% 60% ± 3% 69%

Tile drain phosphorus is highly bioavailable

Lake Macatawa: 98 ppb TP (2015 mean)

Lake Michigan: 1 – 7 ppb TP (Bioassay sample)

March 23, 2015 – February 23, 2016

Phosphorus Fraction Grouping Chi-

Square df p-value

SRPSite Location 59.834 8 <0.001

Time 3.4993 11 0.9823

TPSite Location 54.53 8 <0.001

Time 4.737 11 0.9432

%SRPSite Location 43.552 8 <0.001

Time 8.5723 11 0.6613

Results: Mean P Concentrations

%SRP

Macatawa Watershed with tile drain sampling sites.

Mean TP (ppb)

0 < 50

50 < 100

100 < 150

150 < 200

200 < 250

250 < 300

X2 = 59.834

p < 0.0001

N = 12

N/A

Phosphorus Fraction Grouping Chi-

Square df p-value

SRPSite Location 59.834 8 <0.001

Time 3.4993 11 0.9823

TPSite Location 54.53 8 <0.001

Time 4.737 11 0.9432

%SRPSite Location 43.552 8 <0.001

Time 8.5723 11 0.6613

Site Acres Drained Crops Winter Cover

Crops Fertilizer Tillage Dominant Soil Hydrologic Type

1 7 Variety No Fish emulsion for some crops No-tillage A/D

2 65 Corn/soybeans No Inorganic fertilizer at spring planting No-tillage C

3 80 Corn NoInorganic fertilizer at

spring planting; manure in fall

Disc-tilled at planting C

4 65 Corn NoInorganic fertilizer at

spring planting; manure in fall

Disc-tilled at planting A/D, B

5 22 Corn NoInorganic fertilizer at

spring planting; manure late summer

Disc-tilled at planting C

6 36 Corn No Inorganic fertilizer at spring planting No-tillage C

7 30 Soybeans No No P-containing fertilizers

Vertical tillage before

plantingB

8 50 Corn NoInorganic fertilizer at

spring planting, manure in fall

Disc-tilled at planting & fall

tillage sub-soiler

C

9 39 Corn Yes: radish, oats, crimson clover

Inorganic fertilizer at spring planting

Vertical till twice during

plantingC

Significant positive linear relationship

y = 0.002x + 0.020

R2 = 0.15

p < 0.05

Season Algae Inoculum Statistical Test Regression Equation Test Statistic p-value

SpringSelenastrum Linear

Regression y = 4217x + 316 R2adj = 0.478 0.0236

Lake Mac Phytoplankton

Spearman Correlation rho = -0.267 0.4933

SummerSelenastrum Linear

Regression y = 12335x + 232 R2adj = 0.289 0.1227

Lake Mac Phytoplankton

Linear Regression y = 132x + 9 R2

adj = -0.145 0.6446

FallSelenastrum Linear

Regression y = -1510x + 385 R2adj = -0.159 0.6060

Lake Mac Phytoplankton

Linear Regression y = 46x - 2 R2

adj = -0.202 0.7104

Lake Macatawa Phytoplankton

Microcystis

Tile drains are a source of bioavailable P to the watershed Above current Lake Macatawa P concentrations

Tile drain P concentrations vary temporally and spatially

Significant positive relationship between %SRP and acres drained

Unexpected response in bioassays

Change in Lake Macatawa algal community

TP Load 25% 35%

0.2 lb yr-1

(lowest) 85 11918.7 lb yr-1

(highest) 8,238 11,533

References Ogdahl, M., and Steinman, A. D. (2015). Project Clarity 2014

Annual Monitoring Report.

Walterhouse, M. (1999). Total Maximum Daily Load (TMDL) for Phosphorus in Lake Macatawa.