Annual CI, and bloom area (>0.001 CI equivalent to >10⁵ cells mL⁻¹) for each year, the average Q for March to June, and the total TP and SRP loads for March to June, and total TP load for June only.

*<p>indicates TP_June/TP_March-May ratio of >0.2.</p

R² and residual standard error (RSE), excluding 2011 from the analysis. Q exp is exponential relationship, Q lin is linear relationship.

<p>P-value thresholds: r²>0.45, p<0.05; r²>0.63, p<0.01.</p

Monthly mean water temperature in western Lake Erie from 2002–2011. Tick marks indicate July of each year.

<p>Monthly mean water temperature in western Lake Erie from 2002–2011. Tick marks indicate July of each year.</p

Spring (March to June) load of NOx nitrogen compared to CI showing the lack of a relationship (r² = 0.29, p = 0.11).

<p>Spring (March to June) load of NOx nitrogen compared to CI showing the lack of a relationship (r² = 0.29, p = 0.11).</p

Aerial photograph of <i>Microcystis</i> bloom in western Lake Erie, early in the 2009 bloom, showing the spatial variability during intense blooms.

<p>“A” shows less dense and mixed bloom, “B” shows denser bloom aggregating at the water surface. Mixing can be seeing within the boat wake. Image width is approximately 400 m (credit Tom Archer).</p

Bloom intensity from 2002 to 2011 compared to loads with CI of 1 equivalent to 300 km² of 10⁵ cells mL⁻¹ (A) TP for June, with regression for eight years excluding 2004 and 2011; (B) cumulative TP for March to June with regression (and regression confidence interval) for bloom years (filled squares); (C) cumulative SRP for March to June like (B) with regression line and confidence for bloom years; (D) average Q for March to June, with linear and exponential regression for bloom years.

<p>Shading in (d) indicates the RSE for each of the two regressions, which closely matches the regression confidence (except near 2011).</p

Mean of the three 10-day composites (identified by circles in <b>Figure 2</b>) used to compute intensities for each year for western Lake.

<p>Black indicates CI< = 0. Brown is land. Maumee River input is the far western end of the lake (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0042444#pone-0042444-g001" target="_blank">Figure 1</a>).</p

Observed and modeled CI. CI determined here (black squares) from 2002–2011.

<p>Period of projected CI is shown in light gray, with black circles giving projected CI based on reports of blooms or not. 1995 and 1998 blooms are assumed to be equal to 2003, other years are assumed zero (no bloom) based on lack of reports. Red circles are CI estimated from exponential Q model. Green triangles are CI from TP for June. Triangles with an X have ratio of TP_June/TP_March-May >0.2. Dark gray shade marks time period when the models fail to predict occurrence or absence of blooms.</p

R² for all 10 years between maximum CI and the load of interest for months with positive correlation.

<p>March-May and March-June are the average of the months for Q and the cumulative for TP and SRP.</p><p>p-values: r²>0.3, p<0.10; r²>0.4, p<0.05.</p

R² and residual standard error (RSE) for all 10 years and bloom years between maximum CI and the combined loads of March to May, March to June (in bold), and March to July.

<p>P-value thresholds, for all years: r²>0.4, p<0.05; r²>0.58, p<0.01; r²>0.74, p<0.0014.</p><p>P-value thresholds for bloom years: r²>0.66, p<0.05; r²>0.84, p<0.01; r²>0.84, p<0.01.</p><p>June has a strong influence on the statistics for the bloom years.</p