Colonization Dynamics of Potential Stowaways Inhabiting Marinas: Lessons from Caprellid Crustaceans

Round 1

Reviewer 1 Report

The manuscript is interesting, the research can really be useful for monitoring and managing biological invasions in marine ecosystems.

I have  questions regarding statistical analysis:

1) As far as I can see from the text, the authors performed the analysis in the following sequence:

- checked the data for the homogeneity of the variance and carried out the necessary procedure if the dispersion is not homogeneous,

- then did an ANOVA test

 - and then carried out PER-MANOVA.

The MANOVA tests the effect of multiple independent variables on multiple dependent variables.

The ANOVA test (here it is three-factor) checks the dependence of one dependent variable on several independent ones.

And to further refine the differences between the samples, a post-hoc test is used. The authors wrote that they used it after ANOVA.

But I do not understand why the authors use ANOVA first, and then MANOVA. Apparently, it made sense in the reverse sequence of actions: first, do a MANOVA test. See which variables affect which dependent variables. Then, based on the results of the MANOVA test, conduct an ANOVA test with those variables that reliably depend on some factors. And only then, for clarification, a post-hock test.

2) In addition, the authors write that "To reduce type I error, the level of significance was reduced to P < 0.01"

What is the meaning of this? There is a casuistic inaccuracy here.

 Indeed, according to the test results, it is clear that there are no controversial points: there is no value of 0.05. I recommend that the authors change phrase to something like "test results ... were statistically significant at p<0.01".

3) Also, the authors did not write whether there was a  the normality test. After all, the options for the applied analysis of variance depend not only on the homogeneity of the variances, but also on the type of data distribution.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf

Reviewer 2 Report

The manuscript contains interesting information about abundance of caprellids in several marina localities, as well as the intensity of establishment of these organisms on new substrates. The authors found and evaluated the population dynamics of two obvious invasive species, species whose origin remains unclear, and native ones.

The identification of all species was carried out by morphological methods only without involving molecular genetic analysis. This allows us to request additional illustrative material from the authors, which could confirm the correctness of their identification for two clear invasive species at least. I would recommend adding one more illustration with at least clear photographs of these crustaceans or drawings of taxonomically important elements of the external structure to the article.

Although the article is devoted to the effectiveness of colonization of new substrates by invasive species, it becomes obvious from the materials presented in it that both confirmed and suspected (cryptogenetic) invader species seem to be actively displace the native species, Caprella acanthifera, whose abundance is noticeably lower than invaders, and not present on all localities. This fact, in my opinion, should be discussed in the Discussion and brought to Conclusions. This would give additional interest to readers who are dealing with conservation of biodiversity in marine ecosystems.

Author Response

Please see the attachment.

Author Response File: Author Response.pdf