manuscript/f1000_revisions/taranu_comments.md

In USEPA/Microcystinchla: Code, Data, and Manuscript for NLA, microcystin, Chl analysis

General comments This study provides an elegant framework to predict the severe impairment of U.S. lakes and reservoirs by cyanobacterial harmful algal blooms. I especially appreciated the clever use of conditional probability analysis to identify chlorophyll a threshold above which MC concentrations exceed WHO drinking water and recreational provisional guidelines. Chlorophyll a is a regularly measured water quality variable, and this study indeed offers a promising approach that can me used in many lakes around the world to identify problematic lakes or regions. In that regard, it would have been interesting to account for the spatial heterogeneity across this landscape -- as indicated by Beaver et al. (2014), some regions of the continental U.S. are more likely to be MC hotspots. Accounting for this heterogeneity will likely help explain some of the noise in the biplot shown in Fig. 2. I have also analyzed the MC data from the same dataset and found that accounting for different ecoregions in my model (as presented in Beaver et al., 2014) helped further explain the probability of detecting versus failing to detect MC in lakes. I am curious to know how this would play out with your modeling approach (conditional probability analysis).

Minor comments I recommend the following minor typographical corrections:

P3 Change: “Yuan et al. (2014) explore these associations in detail and control for other related variables. In their analysis they find that total [...]” To: “Recently, Yuan et al. (2014) explored these associations in detail and controlled for other related variables and found that total [...]”

Change: “Given these facts, it should be possible to identify chlorophyll a concentrations that would be associated with the [...]” To: “These findings suggest that chlorophyll a concentrations could also track the [...]”

Change: “Identifying these associations would provide another tool for [...]” To: “Identifying this association would provide an important tool for [...]”

Change: “We add to past studies by exploring associations with newly announced advisory [...]” To: “We build on past studies by exploring associations with the newly announced advisory [...]”

P4 Change: “Thus, to identify chlorophyll a concentrations of concern we identify the value [...]” To: “Thus, to identify chlorophyll a concentrations of concern we identified the value [...]”

Change: “were highly skewed right,” To: “were highly right skewed,”

Change: “Lastly, we assess the ability of” To: “Lastly, we assessed the ability of”

Change: “We use error matrices and calculate total accuracy” To: “We used error matrices and calculate total accuracy”

Change: “For chlorophyll a, the range was” To: “Chlorophyll a ranged from” Please specify that this chlorophyll a range corresponds to a range from oligotrophic to hypereutrophic lakes.

Change: “The associations between chlorophyll a and the upper confidence interval” To: “The association between chlorophyll a and the upper confidence interval”

Figure 2 should first be presented in the Results section.

Change: “This is the case as the probability of exceeding each of the four tested health advisory levels increases as a” To: “Indeed, the probability of exceeding each of the four tested health advisory levels increased as a”

Change: “We used this association to identify chlorophyll a concentrations that are associated” To: “We used this association to identify chlorophyll a concentrations that were associated”

References 1. Beaver J, Manis E, Loftin K, Graham J, Pollard A, Mitchell R: Land use patterns, ecoregion, and microcystin relationships in U.S. lakes and reservoirs: A preliminary evaluation. Harmful Algae. 2014; 36: 57-62 Publisher Full Text

USEPA/Microcystinchla documentation built on May 9, 2019, 5:23 p.m.