Peer review of: Extreme rainfall events alter the trophic structure in bromeliad tanks across the Neotropics (2020)


 

 

Reviewers' Comments: 
 
Reviewer #2: 
Remarks to the Author: 
The authors have responded adequately and I believe this is a solid accetable piece 
 
 
 
Reviewer #3: 
Remarks to the Author: 
The authors designed an experiment to quantify the effects of extreme precipitation events (droughts 
and floods) on macroinvertebrate assemblages that reside in bromeliads. The experiment was 
adequately replicated at multiple sites in the Neotropics, with the aim of having a broader view of 
fluctuations in precipitation. Standing stock, biomass ratio and body size ratio were used as response 
variables to rain manipulation. 
 
The results were robust, and the general patterns were maintained at the different Neotropical sites 
(with some exceptions - detritivore standing stock). During stable hydrological conditions, detritivore 
biomass was higher, while predator biomass was higher during infrequent rainfall. The authors provide 
some hypotheses to explain why large numbers of predators were supported under drought 
conditions. 
 
Looking at the previous revisions, the authors made a great effort to answer, argue, expand, and 
solidify each of the previous reviewers' comments and suggestions. However, I do not agree with the 
modification that the authors made to the title. I will argue this below. 
 
Comments to responses to previous reviews. 
 
All comments from previous reviewers were adequately addressed by the authors. I only have one 
concern with the following comment: 
Reviewer #1 suggested modifying the title to avoid being too broad and encompassing all freshwater 
ecosystems, a suggestion that I agree with. The authors modified the title to include natural 
freshwater microcosms. However, I wonder whether the word “microcosm” is adequate in this context. 
When I read the title, I thought the study was a laboratory experiment under fully controlled 
conditions. I understand that the Authors refer to "natural ...". But, I suggest that the authors 
continue looking for other more appropriate title options. Here is a potential option: "Extreme rainfall 
events alter the trophic structure in bromeliad tanks across the Neotropics". 
 
 
Personal Comments. 
 
Line 96 Are all detritivores small organisms? Are there any large detritivores, either as mesopredators 
or predators? 
I understand that detritivores were classified by feeding trials, gut content, isotopes, and not by size. 
 
Line 125 "... trophic interactions (e.g., competition and predation) ..." 
 
Line 126 As above, I am concerned with referring to all small organisms as detritivores. There are 
many small organisms that are considered predators, some of which were found in this study (e.g., 
Ceratopogonidae, Corethrellidae). 
 

Line 134 I am not sure if “currency” is a good adjective for biomass. Why not use "metric"? 
 
Line 144-145 I suggest “…to investigate the effects of rainfall changes on…” 
 
Line 155 This is not very descriptive: ...Ambient levels. Can you use: “Normal variability of…”, or 
“Regular variability of the rainfall components…” 
 
Line 179 “smaller organisms” are not all detritivores. 
 
Line 247 “smaller organisms” are not all detritivores. 
 
Line 253 I suggest: “Predators may still be able to persist in such drought conditions because of high 
biomass turnover by fast-growing organisms”. 
 
Line 270-275 Could the mesopredators be less sensitive to changes in precipitation because their 
feeding range (i.e., prey) includes microorganisms (not quantified in this study) and 
macroinvertebrates? 
 
Line 544-547 I do not understand what the authors call detritivores. They have several functional 
feeding groups in Table S3, but only mention four taxa in this line. Throughout the manuscript, did 
you only use these 4 taxa for the analyses or did you combine several functional groups (e.g., Filter 
Feeders, gatherers, shredders) and called them detritivores? 
 
Line 579-580 When the Authors washed the bromeliads, they placed all debris and macroinvertebrates 
in the same container, and then took out the aliquots? Can you clarify this in the text? 
 
Line 590-592 If the experiment ran for 60 days, during which the authors placed the bromeliads under 
a shelter, how did they deal with the possible evaporation of water? 
Were you constantly replacing water to maintain the treatment (drought and flood) properly?