First Record of a Cannonball Jellyfish Bloom (Stomolophus sp.) in Venezuelan Waters

Round 1

Reviewer 1 Report

Comments and Suggestions for Authors

Please refer to the attached PDF for details on the comments and suggestions for authors.

Comments for author File: Comments.pdf

Author Response

Reviewer 1

Overall impression

The manuscript ‘First record of a cannonball jellyfish bloom (Stomolophus sp.) in Venezuelan waters’ describes the first bloom event in the coast of Venezuela of the jellyfish Stomolophus sp. The results are of interest for this region, which lacks of studies about jellyfish and its dynamics, and are appropriate for the Journal of Marine Science and Engineering. Authors collated data on the species distribution in the western Atlantic, and explored the environmental conditions that could triggered strobilation and subsequent bloom formation.

The study is timely, however, the justification on the methodology and results, in my opinion, lacks robust evidences. I think the Introduction is disconnected from methods and results due to an insufficient description of the background knowledge of polyps habitats, species life cycle, and experimental studies on strobilation. It is also risky to speculate that polyps are present in that area based on a unique bloom, formed only by adult specimens. I believe authors should be more self-critical about the limitations of their observations.

The study is well-written, but need important changes regarding the structure of the Introduction and Discussion (see my comments below). I expected that the Introduction would give readers an overview of what we know about the species' life cycle, growth rates, current hypotheses about polyp strobilation (trigger factors, number of ephyrae liberated), and the lack of knowledge about polyp distribution in nature, since the results focus on understanding the environmental conditions before, during, and after the bloom. These aspects would support the hypothesis that polyps are present in the area and not advected from others. Now the focus is on jellyfish fisheries, taxonomic features of the genus, and on its trophic ecology, but details on life cycle are absent.

My decision is major revision.

Hope my comments are useful to improve the manuscript and I wish success to the authors.

Authors: Thank you for the time invested in providing these insightful suggestions and for your positive evaluation of the manuscript.

 

Specific comments about the text and figures:

Abstract:

It is well-written. I strongly recommend that you indicate polyps were not found in the field, because now with the statement ‘triggered strobilation and subsequent bloom formation’ (line 23) is confusing whether you found polyps or not.

Authors: Thanks for your suggestion. We have revised the abstract to explicitly state that no polyps were observed in the field, ensuring clarity regarding the strobilation process and bloom formation.

 

Introduction:

This section need to be improve. Funnel structure is missing here. It starts with the genus distribution, and tropic ecology, moving to global generalities on jellyfish blooms, to come back again to the genus Stomolophus (fisheries, taxonomic features). The stream of thought can improve starting with paragraph 2, 3 and later move to Americas, the genus and species. Moreover, as the study is focused on the understanding of environmental window for strobilation, I insist in the need of changing the focus of the Introduction to the background on the life cycle, strobilation triggers, optimal conditions for bloom formations, etc. Some important references are absent here.

- You could explain that only two species of this genus are considered valid (Jarms and Morandini 2019). Lopez-Martınez et al. (https://link.springer.com/article/10.1007/s10750-020-04182-5) proposed the use of Stomolophus c.f. meleagris for the species. Here, it could be an option too.

Authors: The introduction has been rearranged to conduct the stream of thoughts better. Now, it starts with the generalities and interest of jellyfish blooms that are connected to the interest of the genus Stomolophus (i.e., fisheries) and its characteristics (taxonomic guidance for its identification, life cycle, ecological aspects, and distribution) to conclude with the goals of this study and its interest to the public. We have revised the manuscript to clarify that only two species within the genus Stomolophus are currently considered valid, following Jarms and Morandini (2019). Additionally, we acknowledge the taxonomic uncertainties highlighted by López-Martínez et al. (2020) and recognise adopting the designation Stomolophus c.f. meleagris could be an appropriate option. However, since no genetic analyses were conducted, we have opted to maintain the designation Stomolophus sp.

 

- Line 39: This genus is also present in the Pacific. One of the references you cited indicated that (Jarms and Morandini 2019), but also you are missing some references (e.g., Gómez Daglio L, Dawson M N (2017) Species richness of jellyfishes (Scyphozoa: Discomedusae) in the Tropical Eastern Pacific: missed taxa, molecules, and morphology match in a biodiversity hotspot. Invertebrate Systematics 31, 635-663, and Sastré-Velásquez CD, Rodríguez-Armenta C, Minjarez-Osorio C, De La Re-Vega E. Estado actual del conocimiento de la medusa bola de cañón (Stomolophus meleagris). Epistemus (Sonora). https://doi.org/10.36790/epistemus.v16i33.245)

Authors: We appreciate the reviewer’s observation and have updated the manuscript to acknowledge that Stomolophus is also present in the Pacific, as noted in Jarms and Morandini (2019). We have also incorporated additional relevant references, including Gómez Daglio & Dawson (2017) regarding species richness in the Tropical Eastern Pacific and Sastré-Velásquez et al. (2022) on the species’ ecological and fisheries significance in Mexican waters.

 

- Repeated information on Introduction and Discussion: Line 82 ‘At least 15 species have been identified as candidates for harvesting’ and line 350 ‘with at least 15 species identified as candidates for commercial exploitation’. It is only one example, but there are many paragraphs in which I feel that I am reading the same information twice. If you focus the Introduction on what we know about species distribution, life cycle, strobilation, later in the discussion you have space to discuss about the potential uses of jellyfish as a resource.

Authors: Thank you for noticing. We have expanded and reorganised some details in the Introduction and moved paragraphs to the Discussion, as well as deleted or substituted information in the manuscript to avoid repeating the same information.

 

- Line 115: ‘Given that we could not collect material for genetic analysis, we only refer to the specimens as Stomolophus sp.’ This sentence is lost here as you are still introducing the topic and we do not know you found the species. In my opinion, this sentence should be moved to Results section.

Authors: Thanks for your suggestion, we have moved the statement regarding the lack of genetic analysis from the Introduction to the Results section, as this is a more appropriate location.

 

- Line 116: ‘The genus can be distinguished…’ and line 36 ‘the genus…’ : Both ideas should be together. Reading about the genus at the beginning and at the end broke completely the funnel structure expected in an Introduction.

Authors: We appreciate your suggestion and have restructured the Introduction to ensure a more coherent general-to-specific storyline. Specifically, we have merged the taxonomic and morphological descriptions of Stomolophus into a single section at the beginning of the Introduction.

 

- Line 117: ‘by the following diagnostic characters:’ please, add references for this statement.

Authors: Thanks for your suggestion. We have added three references to support this statement:

“The genus can be distinguished by the following diagnostic characters: hemispherical to spherical bell with thick mesoglea; central mouth surrounded by a prominent manubrium formed by the fusion of oral arms; eight pairs of scapulets (small, secondary mouth arms) arising from the pillars of the arm disc; oral arms with numerous club-shaped appendages; a well-developed ring canal system with 16 radial canals [Lu et al. 1992; Jarms & Morandini 2019; Morandini et al. 2024]”

- Lu, N.; Zhao, Y.; Jiang, S.  The morphology and structure of Stomolophus meleagris L. Agassiz. Fish. Sci. (Liaoning). 1992, 11, 5–8 (in Chinese).

- Jarms, G.; Morandini, A.C. World Atlas of Jellyfish; Dölling und Galitz Verlag: Hamburg, Germany, 2019; p. 816.

- Morandini, A.C. Morphology of Rhizostomeae jellyfishes: What is known and what we advanced since the 1970s. Adv. Mar. Biol. 2024, 98, 61–97. https://doi.org/10.1016/bs.amb.2024.09.004

 

- Lines 121-122: ‘Historical records of Stomolophus sp. in Venezuela remain scarce, and it is unclear whether the species is a visitor brought near the shores by ocean currents or whether it has already been capable of settling.’ This is a key point. It seems too far-fetched to describe which environmental variables promote strobilation if we don't know where polyps are, unless it is well-founded on laboratory knowledge, or currents on the area.

Authors: We appreciate the reviewer’s comment and have revised the manuscript to clarify that Stomolophus sp. has been historically recorded in Venezuela [Trinci 1906; Stiasny 1931] providing the first documented occurrence. Instead of suggesting that the species might be a recent visitor or transported by ocean currents, we now emphasise that the scarcity of records is likely due to the limited number of jellyfish specialists and dedicated studies in Venezuela, rather than the species' absence.

 

- Equivalent sentences. Please, synthetize and avoid repeating ideas: Lines 123-124: ‘The bloom of Stomolophus sp. in Venezuelan waters reported in this work represents the first massive appearance of the species within the region’ and line 131: ‘we report an unprecedented or previously undocumented large bloom of Stomolophus sp. from Venezuelan coastal waters.’

Authors: Thanks for your suggestion. We have synthesized the text to eliminate redundancy while maintaining its key messages, as follows:

“This study reports the first documented large bloom of Stomolophus sp. in Venezuelan coastal waters, highlighting its potential ecological and socio-economic significance. Given the species' commercial importance in neighboring countries and its role in regional food webs, understanding the environmental drivers of this event is crucial. We analyze the environmental conditions (sea surface temperature, precipitation, salinity, and chlorophyll a concentration) in the pre-bloom phase (3 months prior) and during the bloom using open-source satellite-derived data to delineate triggering causes.”

 

- Line 133: ‘in the pre-bloom phase (3 months prior)’: To arrive here, I was expected to be convinced base on strong evidence state in the Introduction.

Authors: We appreciate the reviewer’s suggestion. We have revised the Introduction to include evidence supporting the selection of a three-month pre-bloom period, as follows:

“Jellyfish blooms are often associated with environmental changes, such as fluctuations in water temperature, salinity, nutrient levels, and ocean currents, and recent studies have set up a debate on whether or not climate change and anthropogenic activities are affecting the appearance and intensity of those blooms [Purcell 2007; Condon et al. 2013; Pitt et al. 2018; Gamero-Mora et al. 2024; Fernández-Alias et al. 2024]. In Stomolophus species, strobilation – the asexual reproductive process that gives rise to ephyrae – has been shown to occur 1–3 months before bloom events, driven by environmental fluctuations such as temperature shifts and increased food availability [Girón-Nava et al. 2015; Treible & Condon 2019]. Understanding these pre-bloom conditions is essential for identifying the potential drivers of jellyfish proliferation.”

 

Materials and Methods:

- Line 150: ‘Occurrence data for Stomolophus spp. were compiled from three open-access’: aim is missing here. Why you did this compilation? Moreover, indicating the range of years of records would give an idea of the presence of the species in Venezuela. For example, in the legend of Figure 2b indicate GBIF (2000-2020), OBIS (2015-20xx), etc. Were previous records only one or few specimens? Stranding or swimming animals?

Authors: Thank you for your comment; we have revised the Materials and Methods section to clearly state the aim of compiling occurrence data – providing historical context for the observed bloom. Additionally, we have included the temporal range of records from GBIF, OBIS, and iNaturalist in both the text and figure legend. Lastly, we have clarified that previous records in Venezuela primarily consisted of isolated specimens, with no prior reports of large aggregations, helping to contextualize the significance of the event described in this study.

 

- Lines 180-185: This must be developed more in detail as the results are based on that (see my comments above about life cycle, strobilation process triggers).

Authors: We appreciate the reviewer’s suggestion and have expanded the Materials and Methods section to provide a more detailed explanation of the strobilation process and its environmental triggers, as follows:

“The timing of jellyfish blooms is closely linked to the strobilation process, during which sessile polyps undergo transverse fission to produce free-swimming ephyrae. In Stomolophus spp., this process is strongly influenced by environmental factors, particularly temperature fluctuations, food availability, and salinity changes [Girón-Nava et al. 2015; Treible & Condon 2019]. Laboratory studies indicate that strobilation in Stomolophus meleagris is triggered by a decline in temperature followed by a subsequent warming phase, a pattern that aligns with seasonal transitions [Helm 2018]. Additionally, increased nutrient input and phytoplankton blooms (proxied by chlorophyll a concentration) provide a food-rich environment that supports ephyrae development and enhances medusa survival [Álvarez-Tello et al. 2016].

Based on this knowledge, we hypothesized that the strobilation process for the observed bloom occurred between November 2023 and January 2024, approximately 1–3 months before the bloom event (March–April 2024). To test this, we analyzed four key environmental variables—sea surface temperature (SST), precipitation (as a proxy for land nutrient input and salinity fluctuations), chlorophyll-a concentration, and sea surface salinity (SSS)—in both the pre-bloom phase (November 2023–January 2024) and the bloom phase (March–April 2024).”

 

- Line 187: ‘The period from November 2023 to January 2024 had all environmental conditions known to trigger the strobilation in Stomolophus sp.’ Please, if we know these conditions, describe them in more detail.

Authors: We appreciate the reviewer’s suggestion and have revised the text to describe the environmental conditions in a more general way, rather than including specific values. This ensures that the information remains descriptive and informative while maintaining a logical flow into the results section where the detailed environmental data is presented.

 

Results:

- Line 198: ‘umbrella diameter between 15 and 20 cm’ and line 204: ‘While no juveniles (subadults) were observed during the bloom’ = all adults, no ephyra around that gives cues on the presence of polyps in the area. For this reason, you need to justify the analysis you made on strobilation period in the area.

Authors: We acknowledge the absence of observed juveniles (subadults) and ephyrae during the bloom, which limits direct evidence of local polyp presence. However, Stomolophus has been recorded in Venezuela before, and while ephyrae have not been documented, their absence in records does not imply their absence in the ecosystem. The lack of ephyrae reports may be due to sampling limitations and the difficulty of detecting early life stages in natural environments rather than a true absence of polyps. Given that blooms of Stomolophus are known to be triggered by environmental factors such as temperature fluctuations, increased primary productivity, and freshwater inputs (extended rainfall) influencing salinity, we justify our analysis by assessing whether these conditions were met in the months preceding the bloom. This approach allows us to infer potential polyp activity despite the lack of direct observations. Further research, including targeted sampling for ephyrae and polyps, is needed to confirm local recruitment and gain a better understanding of bloom dynamics in Venezuelan waters.

 

- Figure 2: need to be improved. Grey land will help a lot to distinguish the points, now is very hard and altitude is not informative at all. To improve readability, keep same color in a and b (Gbif always black, not black first and pink later, it is confusing). Also, if you will keep the ocean blue, please avoid using blue and green in the points. Purple, black, orange, are better options. Figure caption: you can remove ‘(sources: GBIF, iNaturalist®, and OBIS)’, and add the reference of Stiasny (1931) with the correspondent number on References. Why Trinci [36] is not shown here? Please check because now points in Fig b and a are different. For example (but this is happening with many records), iNaturalist has 2 points in Venezuela in Fig. 2a, but those points disappear in Fig. 2b, and only one point of GBIF is shown in the area, and vice versa. If those changes have a reason, please clarify. In addition, why you decided to include only reports from repositories, but not from literature (for example: https://www.publish.csiro.au/is/IS16055)?

Authors: Thank you for all the suggestions. To improve the visualization, we used a new raster layer in gray. The repository records were compiled in a new panel now in the revised version, Figure 2. And as you suggested, we did an exhaustive search for Stomolophus records in the region, and visualized it in what is now Figure 3. We were consistent in using the same colors for the repository case and included the Trinci (1906) record site in the Venezuela map.

- Lines 244-245: ‘showed distinct temporal patterns that align with the life cycle of Stomolophus sp.’. I strongly recommend previously give a context on Stomolophus life cycle, environmental conditions where adults were observed in other areas, to understand when you said ‘align with’. This will make your research more robust, interesting and less speculative. Are the conditions when adults were observed similar to thermal, salinity window for the species in other areas?

Authors: Thanks for your suggestion. We already addressed the Stomolophus life cycle in the Introduction. We also revised the Discussion to concisely compare the environmental conditions observed in Venezuela with those reported for Stomolophus meleagris in the South Atlantic Bight, USA.

 

- Line 248: ‘creating the type of thermal fluctuation known to trigger strobilation in this species’ References for this?

Authors: We have added the reference: Calder [1982] to support this statement.

 

- Figure 3: To be consistent, you can remove the SST, SSC and SSS, and write down the name of the variables, or leave only SSS, SST, SSC and describe the initials in the caption of the figure. Caption: ‘Environmental variable variations’ can be simplified to ‘environmental conditions’? All plots must have same x axis limits: Sep 23-Aug 24. Now Fig. 3c starts in Aug 23 and end in Sep 24. Also, the y axis of Fig. 3c should go until 200 mm ‘with maximum rainfall in October and November 2023 (183.4 and 185.5 mm, respectively)’ (Line 257).

Authors: Thank you for noticing. We have put the full variable names on the y-axis, for consistency. In addition, we have simplified from “Environmental variable variations” to “environmental conditions”, and corrected the plots limits on the x-axis, plus the y-axis limit of Precipitation, panel c.

- Lines 277-281: In my opinion this is part of the discussion and references are needed: ‘The November 2023–January 2024 period appears crucial for understanding the subsequent bloom, as it combined several favourable conditions for Stomolophus sp. asexual reproduction: (1) steady temperature decline likely triggering strobilation, (2) peak chlorophyll a concentrations as a proxy for primary productivity indicating abundant food (primary consumer; zooplankton) resources, and (3) high precipitation potentially enriching coastal waters with nutrients and maintaining low salinity.’

Authors: Thank you for your suggestion. We have moved the interpretation of pre-bloom environmental conditions to the Discussion section, ensuring a clearer distinction between results and interpretation. Additionally, we have included references to support the role of temperature fluctuations, food availability, and nutrient input in triggering Stomolophus blooms, as follows:

“The November 2023–January 2024 period appears crucial for understanding the subsequent bloom, as it combined several favorable conditions for Stomolophus asexual reproduction: (1) steady temperature decline likely triggering strobilation, (2) peak chlorophyll a concentrations as a proxy for primary productivity indicating abundant food (primary consumer: zooplankton) resources, and (3) high precipitation potentially enriching coastal waters with nutrients and maintaining low salinity. These environmental factors align with previous studies demonstrating that temperature fluctuations are a primary trigger of strobilation in Stomolophus spp. [Helm 2018; Treible & Condon 2019]. Furthermore, elevated chlorophyll levels indicate increased primary production, which enhances food availability for ephyrae and juvenile medusae, supporting their survival and growth [Álvarez-Tello et al. 2016]. Additionally, high precipitation rates can introduce terrestrial nutrients into the coastal system, promoting phytoplankton growth and indirectly benefiting jellyfish populations [Purcell 2007; Pitt et al. 2018]. Although direct evidence of local polyps is lacking, the environmental patterns observed in this study are consistent with conditions that have preceded Stomolophus blooms in other regions.”

 

Discussion:

- Lines 290-292: ‘These conditions mirror those reported by Girón-Nava et al. [43] as optimal for successful strobilation and ephyra survival in the Gulf of California, where water temperature transitions and nutrient availability played crucial roles in bloom formation’

Could you add more detail information of what these authors found? In my opinion the similarity is not as obvious. That study reported an increase of SST from around 21 to 30°C and chlorophyll values with a maximum of 12 mg m-³. What do you mean by ‘mirror’? Please, detail. Moreover, check all references, as Girón-Nava et al. [43] is [44].

Authors: We thank you for the comment. We have revised the text to provide a more precise comparison with Girón-Nava et al. (2015), as follows:

“These conditions partially resemble those reported by Girón-Nava et al. [43] as optimal for successful strobilation and ephyra survival in the Gulf of California, where a more pronounced temperature increase (from ~21 to 30°C) and significantly higher chlorophyll a concentrations (peaking at 12 mg m⁻³) were recorded during a major bloom event. Despite these differences, highlight the importance of temperature fluctuations and food availability in bloom formation. Additionally, Girón-Nava et al. (2015) suggested that the northward Gulf of California Current may have played a role in jellyfish transport, indicating that similar current-driven dispersal mechanisms could influence Stomolophus populations in the Caribbean.”

 

- Lines 301-302: ‘The absence of genetic data limits our ability to assess connectivity between Venezuelan populations and established stocks in the Gulf of Mexico, a critical gap given the potential for range shifts under climate change [50]’: You can discuss this in the framework on reference of Daglio and Dawson (2017) Species richness of jellyfishes (Scyphozoa : Discomedusae) in the Tropical Eastern Pacific: missed taxa, molecules, and morphology match in a biodiversity hotspot. Invertebrate Systematics 31, 635-663 and Getino-Mamet, L. N., L. G. Daglio & F. J. Garcıa-De-Leon (2019). High genetic differentiation in the edible cannonball jellyfish (cnidaria: Scyphozoa: Stomolophus spp.) from the Gulf of California, Mexico. Fisheries Research 219:105328. Despite these references are not on Venezuelan waters, it is interesting discuss what we know on species genetic diversification in the area.

Authors: Thanks for your comment. We have incorporated insights from Getino-Mamet et al. (2019) and Gómez-Daglio & Dawson (2017) to expand the discussion on genetic differentiation in Stomolophus spp. The revised text acknowledges the cryptic diversity and distinct genetic lineages identified in the Gulf of California, highlights the absence of genetic data in our study, and emphasizes the need for future research to assess connectivity between Venezuelan populations and those in the Gulf of Mexico. Additionally, we frame this Discussion within the broader context of jellyfish biogeography in the Tropical Eastern Pacific and Caribbean regions, as follows:

“Population genetic studies on Stomolophus in the Gulf of California have revealed significant genetic differentiation, suggesting the presence of multiple cryptic lineages [Gómez-Daglio & Dawson 2017; Getino-Mamet et al. 2019]. Using mitochondrial COI sequences and microsatellites, Getino-Mamet et al. (2019) identified two distinct genetic lineages: Stomolophus sp.1 in the Golfo de Santa Clara and Stomolophus sp.2 in the southern Gulf of California and Baja California Pacific coast, with divergence estimated at 1.17 million years ago. These findings align with broader patterns of high genetic differentiation and restricted gene flow in scyphozoan jellyfishes, as reported by Gómez-Daglio & Dawson (2017) in their comprehensive analysis of jellyfish diversity in the Tropical Eastern Pacific.”

 

- Line 306: ‘period of 1–3 months required for ephyrae to reach the medusa stage [51]’ Is this reference based on three Semaeostomeae species? There is no research on Rhizostomeae or the genus Stomolophus with a growth rate estimation?

Authors: Thank you for pointing out this detail. You are correct, the Treible & Condon (2019) reference is based on three of Semaeostomeae. We have revised and replaced this reference to: “Calder 1982; Fernández-Alías et al. 2023”, for the 1–3-month period required from ephyrae to reach the medusa stage.

 

- Line 315: ‘raises questions about’, Line 318: ‘raises important questions about’, Line 337: ‘raises questions about’. Check for other expression to avoid repetition.

Authors: Thank you for your observation. We have rephrased to “calls into question” to avoid expression repetition.

 

- Lines 322-324: ‘Similar range expansions have been observed for other jellyfish species in response to environmental changes [9], though care must be taken in attributing such events to climate change without long-term monitoring data [11]’: you can include here examples of jellyfish potential expansion in south America (e.g.:https://mbr.biomedcentral.com/articles/10.1186/s41200-016-0093-7).

Authors: We thank you for the suggestion and have incorporated the example of Tamoya haplonema's potential expansion in South America, as documented by Leoni et al. (2016), to strengthen our discussion on jellyfish range expansions in response to environmental changes.

 

- Lines 333-338: ‘government exported after this recorded bloom 156 tons of Stomolophus jellyfish to South Korea on 12 October 2024. And The government claims that Stomolophus jellyfish represent a valuable and underutilised resource’. Please, add references here (I suppose references 53, 54, 55 comes here).

Authors: Indeed, actually is the reference from “El Impulso 2024”, all the information related to the exportation of the Stomolophus jellyfish to Hong Kong. We have added the reference hereafter “valuable and underutilized resource”, for more clarity.

 

- Lines 332-341 and 359-373 could be put together and synthesized, same ideas but mixed within the text.

Authors: We appreciate your suggestion. We have merged the two paragraphs to improve clarity and coherence. The revised text removes redundancy by integrating government actions, media coverage, and sustainability concerns, while highlighting infrastructure limitations, market challenges, and interannual variability in jellyfish abundance. Additionally, we emphasize the need for a sustainable management framework, drawing from the Gulf of California fishery as a reference.

Reviewer 2 Report

Comments and Suggestions for Authors

This research is very significant, as it documents the first massive records of a cannonball jellyfish bloom in Venezuela, especially in relation to environmental factors. The findings highlight the importance of further research, including genetic analyses, to confirm species identity and investigate the drivers behind this unprecedented bloom. The manuscript is well-structured; there are a few important corrections we highlighted in our review to consider enhancing the quality of this research.

Comments for author File: Comments.pdf

Author Response

This research is very significant, as it documents the first massive records of a cannonball jellyfish bloom in Venezuela, especially in relation to environmental factors. The findings highlight the importance of further research, including genetic analyses, to confirm species identity and investigate the drivers behind this unprecedented bloom. The manuscript is well-structured; there are few important corrections we highlighted in our review to consider to enhance the quality of this research.

Reviewer Comment: For line 2, it is recommended to change the title from “First record of a cannonball jellyfish bloom…” to “First massive records of a cannonball jellyfish bloom…”.

Authors: Thank you for the suggestion. We believe that the term massive within the title can help a reader not acquainted with the terminology used in jellyfish studies. However, following Hamner & Dawson (2009) recommendations on it, the term blooms implicitlly involves a “massive occurence” so we have decided not to include the term on the title.

On the contrary, to make it more accesible, “mass occurence” has been incorporated as a keyword

 

Because we found previous GBIF records of this jellyfish in Venezuela. Kindly check the sources of the details below.

 

 

 

Source: https://www.gbif.org/occurrence/map?country=VE&taxon_key=2264557

 

Source: https://www.gbif.org/occurrence/2864884474

Authors: Thank you for your insightful comment about the GBIF records. We already checked the links suggested and are aligned with the records that we already have, as you can see in Figure 2a (repositories’ records) and Figure 3 (Literature records). Please check the reply to Reviewer 1 comments for further details on these amendments.

 

Reviewer Comment: For lines 108 – 109, the Authors mentioned that “The cannonball jellyfish appears seasonally abundant (primarily in the dry season) across the Gulf of Mexico and the Caribbean Sea [Morejón-Arrojo et al. In Review]”; we suggest the Authors to add additional details, including yearly-monthly blooms records, and include peer-reviewed references too, if possible. Here, we found a published paper addressing the monthly appearance of this jellyfish “In NW Mexico, it is quite relevant to detect young jellyfish stages because when the species Stomolophus sp. (cannonball jellyfish) is blooming, it is exploited economically by local fishermen,… In general, the presence of ephyrae extends over the winter and spring seasons, during which time the presence of adult organisms can be observed.”

https://doi.org/10.3390/d13060229

Authors: We thank the reviewer for this constructive suggestion. We have incorporated the recommended peer-reviewed reference (Gómez-Salinas et al. 2021) to strengthen our statement about seasonal patterns. This addition provides explicit monthly records of early life stages (ephyrae) and links them to adult bloom timing in the Gulf of California. We retained the citation to our in-review study for a broader regional context in the Gulf of Mexico and the Caribbean, as it specifically addresses Stomolophus phenology across these regions.

 

Reviewer Comment: For line 131, we suggest the Authors to remove “or” from the sentence, as long as they keep “large bloom” the statement is correct: “We report an unprecedented, previously undocumented large bloom…”

Authors: Thanks for your comments. We have revised the paragraph, and now it reads as follows:

“This study reports unprecedented, previously undocumented the first large bloom of Stomolophus sp. in Venezuelan coastal waters, highlighting its potential ecological and socio-economic significance. Given the species' commercial importance in neighboring countries and its role in regional food webs, understanding the environmental drivers of this event is crucial.”

 

Reviewer Comment: The Materials and Methods are very well explained; in fact, it is highly important to explain the jellyfish species identification; as you mentioned, sighting observations were considered, and there was any formation or training conducted to help the fisherman and divers identify this specific jellyfish? : lines 145 to 148, “Following these initial reports, we contacted several local stakeholders (divers and fishermen) about sightings of this unusual event. The bloom period (March–April 2024) was confirmed based on consistent observations of high jellyfish abundances across multiple sites.

Authors: Thanks for your comment. We clarify that local stakeholders provided photographic and spatiotemporal data but received no formal training. Species identification was conducted solely by the research team using diagnostic morphological features (Fig. 1), with ambiguous records excluded. While genus-level identification was robust due to Stomolophus’s distinct traits, we acknowledge the limitation in species-level resolution and recommend future training protocols for enhanced precision.

 

Reviewer Comment: We recommend the Authors to mention the exact area of study in the Materials and Methods because we noticed in the results interpretation of this jellyfish occurrence in other areas, including Venezuela (Figure 2 a-b), or you can put (Figure 2 b) in the discussion part.

Authors: Thank you for your suggestion. We have revised the text to include latitude and longitude ranges, providing greater geographic precision regarding the study area.

 

Reviewer Comment: We suggest the Authors to write for number 4 line 283 “Discussion and Conclusion” instead of “Discussion”

Authors: Thanks for your comment. We have changed the section name to Discussion and Conclusions”, as you suggested.

Reviewer 3 Report

Comments and Suggestions for Authors

Review for the paper "First record of a cannonball jellyfish bloom (Stomolophus sp.) in Venezuelan waters" by Ramón D. Morejón-Arrojo, Florian Lüskow, Alfredo Fernández-Alías, Humberto Ramírez and Aldo Cróquer submitted to "Journal of Marine Science and Engineering".

 

Cnidaria constitute a diverse phylum of gelatinous zooplankton organisms that are ubiquitously distributed throughout the world's marine ecosystems. These organisms play pivotal roles in marine ecological processes, including microbial loop dynamics, trophic interactions within food webs, and biogeochemical cycling of essential elements. Scyphozoans, particularly those exhibiting significant grazing rates on various planktonic organisms, are known to generate extensive population blooms that can substantially alter the abundance and distribution patterns of commercially significant marine taxa. In specific geographical localities, pelagic cnidarians can achieve numerical and biomass dominance within zooplankton and macrozooplankton communities, significantly influencing ecosystem functioning. The proliferation of gelatinous zooplankton has been documented to generate numerous detrimental impacts on both ecosystem stability and anthropogenic activities, including commercial fishing operations, nuclear power plant cooling systems, tourism-related activities, and maritime transportation. Conversely, in various Asian nations, certain medusozoan species represent valuable commercial resources, with similar economic utilization observed for the cannonball jellyfish (Stomolophus meleagris) in American waters. Given these ecological and socioeconomic implications, the systematic monitoring and investigation of jellyfish bloom dynamics, particularly in coastal environments, has become increasingly imperative. The present study documents and analyzes an episodic population explosion of Stomolophus sp. in the southern Caribbean Sea, specifically examining the environmental parameters and ecological factors that contributed to this bloom event within the Venezuelan continental shelf.

 

Recommendations regarding the manuscript structure and content:

 

1. The text appearing in lines 209-215 would be more appropriately situated within the Materials and Methods section, as it pertains to procedural aspects of the study.

 

2. It is recommended that Figure 1a and 1b be augmented with appropriate scale bars to provide accurate size references for the Stomolophus specimens under examination.

 

3. A detailed explanation of the methodological approach employed for estimating total jellyfish abundance should be included, incorporating specific sampling protocols and statistical analyses utilized.

 

4. The discussion would benefit from a comprehensive analysis of potential implications for regional fisheries management, considering that cnidarians are significant consumers of fish larvae and zooplankton. This should include: quantitative assessment of potential impacts on commercial fish stocks, analysis of trophic cascade effects, evaluation of economic implications for local fishing communities, discussion of potential mitigation strategies

 

5. The integration of recent literature on similar bloom events in other geographical regions would provide valuable comparative context for the observed phenomena.

Author Response

Cnidaria constitute a diverse phylum of gelatinous zooplankton organisms that are ubiquitously distributed throughout the world's marine ecosystems. These organisms play pivotal roles in marine ecological processes, including microbial loop dynamics, trophic interactions within food webs, and biogeochemical cycling of essential elements. Scyphozoans, particularly those exhibiting significant grazing rates on various planktonic organisms, are known to generate extensive population blooms that can substantially alter the abundance and distribution patterns of commercially significant marine taxa. In specific geographical localities, pelagic cnidarians can achieve numerical and biomass dominance within zooplankton and macrozooplankton communities, significantly influencing ecosystem functioning. The proliferation of gelatinous zooplankton has been documented to generate numerous detrimental impacts on both ecosystem stability and anthropogenic activities, including commercial fishing operations, nuclear power plant cooling systems, tourism-related activities, and maritime transportation. Conversely, in various Asian nations, certain medusozoan species represent valuable commercial resources, with similar economic utilization observed for the cannonball jellyfish (Stomolophus meleagris) in American waters. Given these ecological and socioeconomic implications, the systematic monitoring and investigation of jellyfish bloom dynamics, particularly in coastal environments, has become increasingly imperative. The present study documents and analyzes an episodic population explosion of Stomolophus sp. in the southern Caribbean Sea, specifically examining the environmental parameters and ecological factors that contributed to this bloom event within the Venezuelan continental shelf.

 

Recommendations regarding the manuscript structure and content:

1. The text appearing in lines 209-215 would be more appropriately situated within the Materials and Methods section, as it pertains to procedural aspects of the study.

Authors: Thanks for noticing. We have moved the text to the Material and Methods section.

 

2. It is recommended that Figure 1a and 1b be augmented with appropriate scale bars to provide accurate size references for the Stomolophus specimens under examination.

Authors: Thanks for your recommendation. We have added into the Figure 1d the scale bar. In the rest of the panels, is not possible to add a scale bar. We hope that you can understand.

 

3. A detailed explanation of the methodological approach employed for estimating total jellyfish abundance should be included, incorporating specific sampling protocols and statistical analyses utilized.

Authors: We appreciate the reviewer’s suggestion; however, this study is descriptive in nature, and a precise estimation of total jellyfish abundance was not feasible given the available data. Observations were based on pictures and qualitative reports from divers and fishers, and no standardised sampling protocol or statistical analyses were applied. Instead, jellyfish abundance was  roughly estimated using the size of the diver and the hand from Fig 1c,d. That is the reason of providing approximated densities rather than accurate ones. .

 

4. The discussion would benefit from a comprehensive analysis of potential implications for regional fisheries management, considering that cnidarians are significant consumers of fish larvae and zooplankton. This should include: quantitative assessment of potential impacts on commercial fish stocks, analysis of trophic cascade effects, evaluation of economic implications for local fishing communities, discussion of potential mitigation strategies

Authors: We appreciate the reviewer’s comment and have integrated a brief discussion on the potential ecological and economic implications of Stomolophus blooms before addressing public and governmental responses. This ensures a logical transition from scientific implications to socio-economic considerations while keeping the discussion within the scope of our study.

 

5. The integration of recent literature on similar bloom events in other geographical regions would provide valuable comparative context for the observed phenomena.

Authors: We appreciate the reviewer’s comment and believe that our manuscript now integrates a comprehensive range of recent literature on jellyfish (Stomolophus) bloom events. If additional references are suggested, we remain open to incorporating them in future revisions.