Survival and Growth of Asellus aquaticus on Different Food Sources from Drinking Water Distribution Systems

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Comments concerning both content and language is attached as one file with comments in consecutive order.

Comments for author File: Comments.pdf

Comments on the Quality of English Language

Author Response

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Author Response File: Author Response.pdf

Reviewer 2 Report

Comments and Suggestions for Authors

The paper „Survival and growth of A. aquaticus…” is of interest concerning how the water lice con survive and reproduce in drinking water distribution systems -  what are the food sources and which growth rates can be reached.

The experimental approach is very simple with batch experiments in small vessels, with weekly transmission of the water lice to fresh water. This is may be the reason of the very high mortality rates. But nevertheless the paper gives some more information of food and survival and focus on this aspect as drinking water pipe inhabitants.

 Another deficit of the experiments are the food concentration being too low, compared with the data of Adcock (1975). Maybe this value is overestimated, and a calculation on carbon basis is a better way, (% carbon offered as food  of the biomass off the water lice in carbon). This gives a change to compare the data with population densities and growth rates given by Gunkel et al. 2021, Water: Water Lice and Other Macroinvertebrates in Drinking Water Pipes: Diversity, Abundance and Health Risk

Another problem are the metal analyses – why did the author analyses heavy metals, but without any toxicological relevant presentation and discussion of the data. Overall there is no need of heavy metal analyses (except iron and manganese), and the results confirm the lack of any heavy metal contamination. It would be better to shorten the paper by the heavy metal analyses.

Introduction and discussion are very good.

Some special remarks:

Table 1: TP3 - pipe is missing

Experiment D: D_BFC-3 must be once B_BFC-4

L223: not was – were

L228 dito

L248: B – C, delete s

L273: not is – was

L519: D_PE_4 is not in the figure

L526: the author mean D_BFN_4 and not D_BFN_3

Table 4: two times D_BFC_3, D_BFC_4 is missing

Author Response

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Author Response File: Author Response.pdf

Round 2

Reviewer 1 Report

Comments and Suggestions for Authors

Thank you for improving the manuscript according to the suggestions.

A few minor comments/corrections are added below together with one remaining conclusion that I still do not understand.

Line numbers refer to the revised manuscript.

Line 420: change “,” to “.“ before "this" or otherwise change ", this" to ", which"

Lines 540-542: I am still not sure how you can conclude that “The difference between the cultured and natural biofilm indicated that the composition and nutritional value of a cultured and natural biofilm can affect A. aquaticus survival.” Below you state: “The ATP-levels and numbers of total and intact cells in the two cultured biofilms were approximately ten times higher than in the natural biofilm”. Whit such a big difference I think that you can only conclude that the numbers of bacteria in the biofilm affect survival. If I misunderstand the concept, maybe you can make it more clear by elaborating which differences in composition and nutritional value you refer to.

Maybe it is because experiment C and D show different results. In C it is clear that Asellus does not survive on PE without biofilm and then in D they survive longer on PE without biofilm than on natural biofilm. This seems too contractionary to be able to draw the above conclusions.

The same applies to line 647: Is it a general conclusion that survival is better on natural than cultured biofilm or is it only because your set-up provided more ATP in the cultured biofilm? Would it be the case if the same volume om biofilm had been present in both set-ups?

Line 670 “of” is missing in the heading.

Author Response

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Author Response File: Author Response.pdf