the Creative Commons Attribution 4.0 License.
the Creative Commons Attribution 4.0 License.
| 07 Jul 2025
Low site diversity but high diversity across sites of depauperate Crustacea and Annelida communities in groundwater of urban wells in Kraków, Poland
Abstract. Crustaceans and annelids are key components of groundwater communities, influenced by both abiotic conditions and biotic interactions. This study assessed their diversity in urban groundwaters accessed via 91 dug/drilled wells in Kraków, southern Poland, subject to chronic anthropogenic disturbance. Invertebrates were recorded in 47 wells, with 19 species-group taxa identified from 28 wells, including eight annelid and 11 crustacean taxa (Ostracoda: 3; Copepoda: 6; Bathynellacea: 1; Amphipoda: 1). Six stygobiontic taxa were detected in 10 wells: Trichodrilus cernosvitovi, Trichodrilus sp., Typhlocypris cf. eremita, Diacyclops languidoides, Bathynella natans, and Niphargus cf. tatrensis. Due to some taxonomic uncertainties, open nomenclature was used where necessary. Species accumulation did not reach saturation, but extrapolation suggested the sampling was near-complete. Alpha diversity was low (1–3 species per well, mean = 1.4), while beta diversity was high (Whittaker index = 12.3), indicating substantial species turnover, a typical feature of groundwater ecosystems. No clear seasonal trends were observed, consistent with previous studies in Kraków. Four main community types were identified. One, dominated by Enchytraeus gr. buchholzi, may indicate degraded conditions, another, with Bathynella natans and Aeolosoma spp., suggests transitional states; a third, dominated by Trichodrilus spp., likely reflects relatively undisturbed groundwater; and a fourth, more heterogeneous type dominated by surface copepods, was ecologically ambiguous. Despite generally low richness and dominance by surface taxa, the presence of six stygobiontic species suggests that at least 20 % of the surveyed wells retain relatively good ecological conditions.
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- CC1: 'RC Comment on egusphere-2025-2883', Fabio Stoch, 26 Aug 2025
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RC1: 'Comment on egusphere-2025-2883', Fabio Stoch, 28 Aug 2025
The study is an interesting overview of groundwater fauna in a urban area, a kind of data quite scarce in recent literature. Conclusions may be affected by the low number of species present, that are reflected also in species accumulation curves and high beta diversity, that can reflect simpoly a random sampling of a very poor cspecies assemblage; maybe conclusions are quite optimistic! In any case a welcomed paper on this important subject, including some species (like Oligochaeta) usually overlooked in subterranean habitats due to the lack of specialists. It is of course a pity that more than one half of copepods were not identified to species level; being the most species-rich taxon in the area, we do not know how this could have been affected results.
I attach the pdf with very few notes and suggestions in text; the most important ones are as follow:
(1) stygobiont is used both as a noun and as an adjective; so "stygobiontic" is not used; please replace this term with stygobiont throughout the text (I highlighted only the terms I noticed); an alternative is to use stygobitic (or, les used, stygobiotic) as an adjective, but if authors feel comfortable with stygobiont it's ok
(2) The copepod Diacyclops languidoides is not a stygobiont by definition; it was described in mires from northern Sweden by Lilljeborg and found in lake litoral enviuronments in Finland. Being a species complex, we cannot be sure the species in Poland and in Sweden is the same; if this is true as probable, even this copepod is a stygophilic (i.e. a non.-stygobiont following the terminology used in the paper); I let to the Authors to think about this point that can change the (already low) percentage of stygobionts
(3) In table 1 please replace copepodites by copepodids (this is the correct term for this larval stage)
(4) In fig. 4 it is clear that the curve is a species rarefaction curce, not a species accumulation curve. The caption of Y axis is correct, however each point has a standard deviation, being a replica of randomly chosen values, not the row species richness value); this is the difference bertween a rarefaction ù(quite smoothed) curve and an accumulation curve (when only row values, and no s.d., should appear); please correct this in figure caption and text. This does not change anything about results.
I suggest this is an interesting paper and the statistical methodology is correct. However, the number of species is very poor, the number of stygobionts is poor as well, and this may influence the results, concealing seasonal differences, increasing beta diversity, and making results less robust (expecially due to the high percetage on unidentified copepods). I strongly suggest authors emphasize these points in the discussion: apart undetermined species, there is nothing they can do, this is the situation in their town: a very poor groundwater fauna, and this result may be interesting in itself.
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AC1: 'Reply on RC1', Agnieszka Pociecha, 08 Oct 2025
Dear Reviewer,
Thank you for your valuable comments regarding our manuscript. We have carefully and conscientiously revised our manuscript based on your comments and suggestions.
In a few cases, we would like to explain certain discrepancies:
Rev: (2) The copepod Diacyclops languidoides is not a stygobiont by definition; it was described in mires from northern Sweden by Lilljeborg and found in lake litoral enviuronments in Finland. Being a species complex, we cannot be sure the species in Poland and in Sweden is the same; if this is true as probable, even this copepod is a stygophilic (i.e. a non.-stygobiont following the terminology used in the paper); I let to the Authors to think about this point that can change the (already low) percentage of stygobionts
Authors: We agree with the reviewer's observations regarding the species Diacyclops languidoides
that it is a difficult species to define in terms of the definition of stygobiont.
However, in our manuscript, as suggested, we clarified while we have classified this species as a D. longuidoides - group but as a stygobiont.
Rev: (4) In fig. 4 it is clear that the curve is a species rarefaction curce, not a species accumulation curve. The caption of Y axis is correct, however each point has a standard deviation, being a replica of randomly chosen values, not the row species richness value); this is the difference bertween a rarefaction ù(quite smoothed) curve and an accumulation curve (when only row values, and no s.d., should appear); please correct this in figure caption and text. This does not change anything about results.
Authors: We used the Species Accumulation Plot routine in PRIMER 7, with the option of randomizing the original sample order 9,999 times. In this procedure, the resulting curves are averaged (with standard deviations) to provide a smooth relationship between the average number of species and the number of replicates. The analytical form of this average accumulation curve (across all permutations) was described by Ugland, Gray & Ellingsen (2003, J. Anim. Ecol. 72: 888–897). We acknowledge, however, that when samples are arranged in their original or any user-defined order (i.e. reflecting non-arbitrary spatial or temporal sequences), the resulting accumulation curve appears as a jagged or stepped function.
Rev: I suggest this is an interesting paper and the statistical methodology is correct. However, the number of species is very poor, the number of stygobionts is poor as well, and this may influence the results, concealing seasonal differences, increasing beta diversity, and making results less robust (especially due to the high percentage on unidentified copepods). I strongly suggest authors emphasize these points in the discussion: apart undetermined species, there is nothing they can do, this is the situation in their town: a very poor groundwater fauna, and this result may be interesting in itself.
Authors: We agree with the reviewer's assessment that the number of species in groundwater is low, but this is characteristic for Central Europe groundwaters. Our materials and obtained results show the image of macroinvertebrate richness and diversity in aquatic subterranean environment in Kraków. In the discussion, we highlighted and clarified this point in relation to the results of other researchers.
Citation: https://doi.org/10.5194/egusphere-2025-2883-AC1
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AC1: 'Reply on RC1', Agnieszka Pociecha, 08 Oct 2025
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CC2: 'Comment on egusphere-2025-2883', Elżbieta Dumnicka, 29 Aug 2025
Dear Dr Stoch,
Thank you for your valuable remarks - we correct the manuscript according to your suggestions.
With best wishes,
Elzbieta Dumnicka
Citation: https://doi.org/10.5194/egusphere-2025-2883-CC2 -
RC2: 'Comment on egusphere-2025-2883', Anonymous Referee #2, 30 Oct 2025
I have only a few minor comments on this manuscript, which I have noted in the PDF. The manuscript is well written, with a logical and coherent structure. The methods appear appropriate and the results are interpreted soundly. However, as I am not familiar with these methods, they should be evaluated critically by a reviewer with specific expertise in this area.
It is somewhat regrettable that DNA barcoding was not undertaken in this study, particularly since the material was, as I understand it, adequately preserved for future molecular analyses. I acknowledge, however, that this approach is not always feasible for all research groups. In the present case, the study based solely on morphological identification already yields interesting results, which could be further refined using molecular data. For example, in the case of oligochaetes, barcoding would help clarify the actual taxa involved, especially within species complexes such as Enchytraeus group buchholzi, Marionina argentea, or Trichodrilus. In other words, more precise taxonomic identification would allow for more robust ecological analyses. I hope the authors will have the opportunity to pursue this direction in the future.
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AC2: 'Reply on RC2', Agnieszka Pociecha, 04 Nov 2025
Dear Reviewer,
Thank you for your opinion and valuable comments regarding our manuscript.
Rev 2: I have only a few minor comments on this manuscript, which I have noted in the PDF.
Authors: Your comments were taken into account in the text.
Rev 2: It is somewhat regrettable that DNA barcoding was not undertaken in this study, particularly since the material was, as I understand it, adequately preserved for future molecular analyses. I acknowledge, however, that this approach is not always feasible for all research groups. In the present case, the study based solely on morphological identification already yields interesting results, which could be further refined using molecular data. For example, in the case of oligochaetes, barcoding would help clarify the actual taxa involved, especially within species complexes such as Enchytraeus group buchholzi, Marionina argentea, or Trichodrilus. In other words, more precise taxonomic identification would allow for more robust ecological analyses. I hope the authors will have the opportunity to pursue this direction in the future.
Authors: It was not possible to perform DNA barcoding tests during the analysis. In the future, we intend to seek out collaborators involved in DNA barcoding analysis more actively.
Citation: https://doi.org/10.5194/egusphere-2025-2883-AC2
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AC2: 'Reply on RC2', Agnieszka Pociecha, 04 Nov 2025
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Publisher’s note: this comment is a copy of RC1 and its content was therefore removed on 28 August 2025.