This study is about functional distinctness in marine communities occupying artificial habitats in urbanized ports. The authors characterized several traits in fouling communities established on settlement plates at two successional stages (after 3 and 13 months) and two habitats (floating and non-floating). They tested whether taxa pools classified as non-indigenous (NIS), cryptogenic, and native would be functionally distinct and whether functional indices of communities would differ between habitats and successional stages. The study is based on data from a previous publication (Leclerc et al., 2020) and encompasses a large spatial extent (10 sites in 4 bays spanning over 100 km of the Chilean coast). The authors found that the taxa pools (NIS, cryptogenic and native) were functionally distinct, but they did not detect functional differences in communities between floating and non-floating habitats. Functional indices varied between colonization stages depending on the site.
Overall, I think the manuscript is adequately presented and contains a theory-rich study that contributes toward comprehending community dynamics in bioinvasion scenarios. The text is well-written, the analyses appeared appropriate and the considerations are balanced. Apart from a few minor revisions described below, I see one main issue regarding the unassigned taxa, i.e., those that could not be classified as NIS, native, or cryptogenic. I elaborate further:

1. A considerable part of the taxa identified in this work was classified as unassigned. I understand that this is a common problem in highly diverse communities, especially when taxonomy is not well known. However, if the unassigned taxa pool actually belongs mostly to one of the assigned classes (NIS, native or cryptogenic) it might change the results regarding their functional differences. For instance, in Figure 1a there is a cluster of unassigned taxa (~10 gray crosses) within the cryptogenic ellipse (in orange), which also overlaps considerably the NIS ellipse (in red). Imagine if these unassigned taxa were actually native. This would likely change the results, once native vs. cryptogenic/NIS taxa pool would (probably) not be functionally distinct anymore. I believe there should be some considerations in that regard in the Discussion section. The authors should give the readers a heads-up on such a potentially important limitation and/or a strong argumentation on why this should not be a problem.

2. About the lack of functional differences in communities from floating vs. non-floating habitats, it also concerns me the weight that the unassigned taxa might have on the results. How does the lack of taxonomic resolution affect the functional indices used in the manuscript (i.e., the functional richness, evenness, divergence, and dispersion)? I understand that the authors employed strategies to try to overcome this issue, but it is not clear how that might have interfered with the calculations of the functional indices and, ultimately, the results and their interpretations. For example, three out of four functional indices take taxa abundance in their calculations. Hypothetically, what if an unassigned ‘taxon X’ is actually two or more species? What is the impact of increasing/decreasing the number of taxa and their abundance for the indices? Are the unassigned taxa evenly distributed among groups under comparison (i.e., similar number of unassigned taxa in both floating and non-floating habitats)? I think all these issues can potentially change results and, consequently, their interpretations. I am aware that the authors have done some consideration on the lack of taxonomic resolution in the discussion section, specifically in the subsection ‘Singularities in temporal changes across sites overcome habitat differences’. But since this is a critical issue, I suggest the authors dedicate a few more lines on that matter, to clarify, ponder, and state a more elaborate argument on why this is not a fatal issue. I do not believe this is a fatal issue, but it needs a deeper appreciation.

Minor revisions
Check 1: Check the usage of double parentheses or parentheses plus brackets when giving examples and inserting citations. There are both cases, and I suggest standardizing for consistency throughout the text (see line 51, page 3, and line 75, page 4).
Check 2: Check the usage of ‘e.g.’ because there are cases where a comma is used after it (e.g., line 70, page 4) and others where it is not (e.g., line 75, page 4). I suggest standardizing for consistency throughout the text.
Check 3: There are a few words that are written in the British English style, while the authors seem to have opted for the American style. Check these words throughout the text. Most of them are about using ‘s’ instead of ‘z’.

Other minor revisions
Line 6, page 1 (Abstract): The first ‘NIS’ abbreviation should come here after the first mention of the whole term.
Line 83, page 4: It seems like a parenthesis is missing.
Line 102, page 5: It seems like there is a misplaced ‘of’ after the word ‘among’.
Line 159, page 8: It seems like the authors are using the American English style, so ‘behaviour defence’ should be changed to ‘behavior defense’ (without the ‘u’ in the first, and with an ‘s’ instead of ‘c’ in the last).
Line 166, page 7: I believe ‘table S1’ should be capitalized (‘Table S1’ instead of ‘table S1’).
Line 233, page 12: The subtitle does not need a full stop (‘.’).
Line 274, page 13: Use ‘defense’ instead of ‘defence’.
Line 274, page 13: The subtitle does not need a full stop (‘.’).
Lines 294-295, page 15: The subtitle does not need a full stop (‘.’) (By the way, nice phrasing).
Line 346, page 17: The subtitle does not need a full stop (‘.’).
Line 365, page 18: The subtitle does not need a full stop (‘.’).
Line 366, page 18: It seems like there is a misplaced ‘across’ after the word ‘composition’.
Line 372, page 18: Use ‘hypothesized’ instead of ‘hypothesised’.
Table 1, page 31: There is a superscript ‘m’ in some of the pairwise comparisons. What does it mean? Also, the meaning of the abbreviations ‘F’ and ‘NF’ is not in the caption. I believe it means ‘floating’ and ‘non-floating’, right?
Figure 1, page 33: The panels ‘c’ and ‘d’ seem to refer to the communities after 3 months and the panels ‘e’ and ‘f’ to the communities after 13 months, right? If so, please indicate in the figure caption or in the figure itself.