We thank the reviewers for their constructive comments and suggestions. We have addressed all the points raised and implemented the suggested changes, including replacing some of the figures and adding new ones, providing a novel online ocean data ecosystem ontology, and modifying the manuscript for improving its clarity and consistency. We hope that the manuscript is now ready for publication in Ocean Science.

Our detailed point-by-point response to the reviewers' comments and suggestions is found below. All page/line/reference/figure numbers refer to the clean version of the revised manuscript. Reviewers’ comments are in regular text, our responses are in bold and new text from the manuscript is in bold italics.

Reviewer 1

Scientific significance

The manuscript is a detailed and predominantly balanced review of published data management practices and infrastructure that summarises the two decades of progress made in the community, the paper is a succinct summary of outputs shared within communities including OceanOBS’19 decadal conference outputs, AGU/EGU informatics, the research data alliance, the European IMDIS community, and likely more that I am not aware of. The manuscript maps these outputs on to the data ecosystem concept of Oliveira et al. (2019). Such a review is a valuable and useful contribution to the literature, albeit it may fall out of date relatively quickly with the pace of advancements in the environmental informatics.

Answer: we thank the reviewer for the positive feedback. In order to ensure the paper relevancy, we added a web-based resource (https://odini.net/OceanDataEcoSystem/) that will be updated regularly, maintaining the paper up-to-date after its publication. The additional tool is referred in the text, as follows (lines 184-188):

“For the purpose of providing an interactive map, we created an online ocean data ecosystem ontology available at https://odini.net/OceanDataEcoSystem/, with an interactive visual representation available at https://webvowl.odini.net. This map is a long-term reference that may be updated and extended. To facilitate contributions and comments from the public, we make the ontology publicly available on GitLab (https://gitlab.com/odini_dev/data-ecosystem-ontology) and invite readers to suggest additions and corrections (ODINI / Data Ecosystem Ontology · GitLab, n.d.; Ontology Documentation generated by WIDOCO, n.d.; WebVOWL, n.d.).”

The manuscript has been submitted to a journal special issue with the scope  "reviews and perspectives" papers, looking back at how ocean sciences have advanced over the last 20 years and looking forward to how they might advance over the next 20 years.

The manuscript addresses significant data management advances made in the last 20 years but there is less emphasis on the next 20 years. The oceanography and informatics community faces significant challenges over the next decades including (not an exhaustive list); the increasing volume of data (it is not uncommon to collect petabytes or more of data during a single expedition), the types of data (recent advances include imagery, acoustics, genomic data), move towards more real time data flows supporting increasingly complex digital infrastructure such as digital twins and AI, and the challenges in data citation and acknowledgement of data usage when it is shared.

The manuscript presents many of these as trends in its final section but does not bring them together with a vision or summary on how the data ecosystem might advance over the next 20 years. Such an addition to the end of the manuscript would fully align the paper to special issue scope and bring what is an extensive and detailed review to a succinct conclusion for the reader.

Answer: We thank the reviewer for this constructive comment. To put more emphasis on the expected evolution of the ocean data ecosystem in the coming 20 years, the following text is now included in section 5 (lines 971-979):

“Looking ahead over the next two decades the ocean data ecosystem is set to undergo further transformations, driven primarily by dramatic growth in the amount and diversity of oceanic data, and by rapid technological developments. The expected increase in data availability and diversity is a natural continuation of the growing use of autonomous and remote sensing platforms, expansion of global observation networks, and improved ability to collect and analyze new data types such as environmental DNA and underwater imagery. Advances in data collection methods results in an unprecedented influx of ocean data each day, often in real-time, propelling ocean research into the era of big data—characterized by vast volumes, diverse formats, and widely dispersed datasets (Tanhua et al., 2019). As in other research fields, the fundamental changes in the characteristics of available ocean data, together with dramatic developments in AI technologies opens the way to data-driven research directions, as exemplified by the digital twin of the ocean initiatives.”

Scientific quality

The manuscript appropriately references recent literature extensively to support the arguments made by the authors. I agree that the community consensus in published literature is toward more open and democratic access to data. However, this does not reflect the consensus of the entire ocean community with significant differences in data culture present across oceanography. These are well covered in “big data, little data, no data” by  Christine l. Borgman. Acknowledging the different data cultures which begin at the definition of what data are would add value to the manuscript.

Answer:  We thank the reviewer for pointing to this discrepancy. In the revised manuscript we address it by adding the following text to 5.1 (lines 989-994):

“We note however that while ocean data literature strongly promotes more open and democratic access to data, ocean scientists, who are responsible for the collection of data, may often be apprehensive, lacking the incentives or resources for sharing the data, and thus taking a somewhat contrasting approach. To account for this discrepancy, which is common in various scientific disciplines (Borgman, 2017), efforts should be made to enhance active data sharing, by facilitating the process of data upload to open access repositories on one hand, and by crediting scientists who do so on the other.”

The NOAA big data program now goes by another name “NOAA Open Data Dissemination (NODD) Program” in its most recent iteration and this section may be in need of update, more information at https://www.noaa.gov/information-technology/open-data-dissemination .

Answer: We reviewed the section to verify its correctness with the recent iteration of the NODD Program and fixed the name of the program.

Presentation quality

The manuscript is well written with appropriate use of English language. It is logically organised using the data ecosystem concept to structure the review makes what is a very detailed review accessible to a broad audience. Figures and tables are appropriate to the manuscript.

Answer: we thank the reviewer for the positive feedback. We note that following comments from reviewer #2 we have made substantial changes in the figures, which contribute substantially to the paper’s clarity.

There is an inconsistency in the use of the major acronyms used throughout the manuscript notable examples include ARGO (historical term) vs. Argo (Argo is the current term) and netCDF vs NetCDF (NetCDF is correct I believe).

Answer: Major acronyms have been corrected for consistency throughout the text. Importantly, the term “ARGO” was replaced with “Argo” and the term “netCDF” was replaced with “NetCDF”.

We thank the reviewers for their constructive comments and suggestions. We have addressed all the points raised and implemented the suggested changes, including replacing some of the figures and adding new ones, providing a novel online ocean data ecosystem ontology, and modifying the manuscript for improving its clarity and consistency. We hope that the manuscript is now ready for publication in Ocean Science.

Our detailed point-by-point response to the reviewers' comments and suggestions is found below. All page/line/reference/figure numbers refer to the clean version of the revised manuscript. Reviewers’ comments are in regular text, our responses are in bold and new text from the manuscript is in bold italics.

Reviewer 2

The manuscript titled “An overview of the ocean data ecosystem” provides a large review of the ocean data ecosystem with a detailed, but not exhaustive, list of definitions, data sources and data product offerings. While the information presented is factually correct, it is difficult to understand and follow. The main goal of the paper was to produce an easy to navigate map, which was not presented. Whilst this paper is a valuable contribution to the literature, it requires major revisions to be a useful resource to the community and structured such that it wouldn’t quickly go out of date.

Answer: We thank the reviewer for their thoughtful feedback and for recognizing the value of our manuscript as a contribution to the literature. We appreciate the comments regarding the clarity and structure of the paper, and we have revised the manuscript with the aim of improving its clarity, readability, and overall usefulness to the community. Importantly, we made changes in the figures -  deleting/replacing unnecessary/unclear ones and adding a number of new ones; created an interactive online ocean data ecosystem ontology that will be used as a long-term up-to-date reference after the paper after it is published; and modified the text to ensure its clarity.

In addition, in order to put in context the various changes that have been made throughout the manuscript, the following text was added to the manuscript (lines 177-182): “By developing a structured conceptual model of the ocean data ecosystem and providing illustrative examples, we intend to support readers in navigating this complex and evolving space. Rather than presenting an exhaustive and potentially quickly outdated inventory, the model is intended to help readers identify and characterize relevant examples (e.g. stakeholders, societal elements, integration tools, data sources and emerging solutions) that are most applicable to their specific domain, use case, or geographic context.  By presenting a flexible and structured framework, the model will serve as a tool to enable to add new developments and technologies, as they emerge in the ocean data ecosystem.”

We hope that by presenting a flexible and structured framework, the paper will serve as a long-term reference that remains relevant as new developments and technologies emerge in the ocean data ecosystem.

General Comments:

The main goal of the paper was to produce an easy to navigate map but no such map is presented in the paper. Two schematics are presented, Figure 2 and 3, however relationships between elements examples is missing. The following description of each element and examples for the ecosystem is presented through a long, but not exhaustive, list that becomes hard to follow and understand. Therefore, the main goal of the paper to have an easy to navigate map is lost. A figure summarising everything would go a long way to helping readers understand and be useful as a resource in the future. A spaghetti diagram/map, so that shows the various divisions of actors/stakeholders and how their roles are interconnected to each other and the resources to better demonstrate the relationships amongst them all. For example, a data aggregator would interact with an actor that provides data, as well as end-users, all while using the resources of data, software and infrastructure to deliver the aggregation. If this was a digital map/resource, it could be updated into the future as the ecosystem continues to develop and grow.

Answer: We thank the reviewer for this valuable and constructive comment, which has been addressed in the manuscript as follows:

• We deleted the original Fig. 1

• We replaced Fig. 2 with a new schematic of the ocean data ecosystem and its elements (now figure 1). The new figure denotes the sections and subsections in which the different elements are discussed, thus serving as a high level overview of the ocean data ecosystem model, and the way it is presented in this paper.

• For each of the sections 3.2 - 3.5 we have added a figure with a schematic showing the elements discussed in it (Fig. 2,3,4 and 11). The new figures are designed to support the reading experience of the article by summarizing the information presented in each section, and to provide a graphical navigation map of the ecosystem. We believe these additions significantly improve the readability and usability of the paper and move us closer to the original goal of providing an accessible overview of the ocean data ecosystem. We thank the reviewer for this excellent suggestion, which has greatly strengthened the paper.
• For the purpose of providing an interactive map which may be kept up-to-date for a long-term reference, we created an online ocean data ecosystem ontology. The on-line tool is open access, and may be updated and extended, thus remaining relevant over time. The additional tool is referred in the text, as follows (lines 184-188): “For the purpose of providing an interactive map, we created an online ocean data ecosystem ontology available at https://odini.net/OceanDataEcoSystem/, with an interactive visual representation available at https://webvowl.odini.net. This map is a long-term reference that may be updated and extended. To facilitate contributions and comments from the public, we make the ontology publicly available on GitLab (https://gitlab.com/odini_dev/data-ecosystem-ontology) and invite readers to suggest additions and corrections (ODINI / Data Ecosystem Ontology · GitLab, n.d.; Ontology Documentation generated by WIDOCO, n.d.; WebVOWL, n.d.).”.

Section 3 of the paper elaborates on the different elements of the Ocean Data Ecosystem model, however this section is 25 pages long, stepping to sub-sub-sub sections. This quickly become hard to read, follow and the main message of the paper is lost. Summarising this information into shorter sections, like Section 3.1 Stakeholders, and providing the additional information through a table, appendix or supplementary material could be a better way to convey this information without losing the goal of the manuscript. This section also follows a different order to the model provided in Figure 2, Stakeholders (Section 3.1), Societal elements (Section 3.2), Data sources and product offerings (Section 3.4), Standards and best practices (Section 3.3), and Emerging technologies (Section 3.5). Different terminologies are also used, e.g., e.g., emerging technologies vs emerging solutions).

Answer: While acknowledging that section 3 is long, we think it contains important information that will be very useful for the ocean science community. As detailed above, to improve the clarity and readability of the paper as a whole, and of this section particularly, we have added figures (Fig. 2,3,4 and 11) that summarise the content of the different subsections in an easy-to-navigate manner. Since the reader can now follow the navigation map and decide where to focus the reading, we left the textual descriptions of the different elements as appear in the different subsections untouched. 

We checked the text for consistency. Specifically, the term “emerging technologies” was changed to “emerging solutions” throughout the text.

The new version of Fig. 1 now refers to the different elements of the ocean data ecosystem in the same order as they appear in the manuscript.

A very long list of data sources, product offerings, interoperability tools and frameworks, and emerging solutions is provided but this list is not exhaustive nor is it clear why some has been chosen to be included but not others. This section would be significantly improved by providing examples to explain the element in the model rather than presenting an exhaustive list which will inevitably miss things and quickly be outdated. However, an extensive list is a useful resource, so perhaps this again could be provided as a digital resource to accompany this manuscript which could be updated beyond the publication of this manuscript to remain in date.

Answer: We thank the reviewer for this insightful comment. A number of revisions were made to address the drawbacks that were pointed in it. First of all, we followed the reviewer’s suggestion and implemented a new web-based tool accompanying the paper, with an interactive visual representation available at https://webvowl.odini.net. This map provides the reader a long-term reference, open, and may be updated and extended. The web-based tool will be updated regularly, maintaining the paper up-to-date after its publication. This complementary element of the paper and its implications are described in the following texts, which were added to the manuscript:

Lines 183-184: “For the purpose of providing an interactive map, we created an online ocean data ecosystem ontology available at https://odini.net/OceanDataEcoSystem/, with an interactive visual representation that is available at https://webvowl.odini.net. This map is a long-term reference that may be updated and extended. To facilitate contributions and comments from the public, we make the ontology publicly available on GitLab (https://gitlab.com/odini_dev/data-ecosystem-ontology) and invite readers to suggest additions and corrections (ODINI / Data Ecosystem Ontology · GitLab, n.d.; Ontology Documentation generated by WIDOCO, n.d.; WebVOWL, n.d.).”

Lines 1072-1076: “To maintain long-term relevance, the ecosystem model presented is aimed to be used as a tool in further characterization of the ocean data ecosystem. The examples given are not exhaustive, and the reader may further identify relevant examples within their domain. The model has been placed as an open online resource as an ontology, describing the elements of the data ecosystem as classes, and examples as instances with relationships. The model and ontology are open to be further validated and refined by the ocean data community”

We agree with the reviewer that description of data sources, tools, and frameworks is not exhaustive. Due to the very broad nature of the ocean data ecosystem, we don’t think it is feasible to cover the large number of elements it contains, and the elements that are presented are given as representative examples. A clarification of this point and an improved of the approach we take, are found in these paragraphs:

Lines 176-182: “Rather than presenting an exhaustive and potentially quickly outdated inventory, the model is intended to help readers identify and characterize relevant examples (e.g. stakeholders, societal elements, integration tools, data sources and emerging solutions) that are most applicable to their specific domain, use case, or geographic context.  By presenting a flexible and structured framework, the model will serve as a tool to enable to add new developments and technologies, as they emerge in the ocean data ecosystem.״

Lines 189-193: “The methodology we used is based on a thorough literature and website review of over 90 scientific articles and over 100 websites. Articles and examples selected to illustrate the elements of the model have been selected based on using search terms such as ‘ocean data,’ ‘ocean data interoperability,’ and ‘marine ontologies.’ The examples are not exhaustive and are intended as a starting point for ocean data professionals, who are encouraged to explore additional resources specific to their research areas.”

This list and the entire paper seem to largely ignore regional efforts in ocean observing. For example,  IOOS is often referenced but not other GOOS Regional Alliances. AtlantOS is referenced in section 3.4.10 but it is unclear why this has been pulled out but not other regional observing systems and their products such as the Southern Ocean Observing System (SOOS) data product, SOOSmap (soosmap.aq).  

Answer: As discussed above, and clarified in the revised version, this paper is not meant to provide an exhaustive list of the ocean data ecosystem elements, but rather to provide a model that is accompanied by representative examples. Accordingly, we provide a number of representative examples for regional efforts, including the EOOS (European Ocean Observing System Framework), EuroBIS (European Node of the international Ocean Biodiversity Information System, and AtlantOS (“AtlantOS - EuroGOOS). 

It is not clear what makes all those listed in Section 3.5 emerging technologies. Some of those repositories and portals mentioned in 3.4 can very easily be included here as well, given the massive push globally to be more interoperable and implement these emerging technologies across all platforms. The “emerging technologies” section would better focused on the strategies and approaches and provide some examples of programs/institutions that are applying those to their already existing (or new) platforms.

Answer: As detailed above, the term  emerging technologies was changed to “emerging solutions”. We agree there is no clear separation line between data sources and emerging solutions, such that some of the data sources may very well provide innovative new approaches for managing ocean data interoperability, and the emerging solutions may be considered data sources of the ocean data ecosystem.  

That being said, the emerging solutions were selected to include examples of different approaches, not necessarily the leading and most prominent efforts, but interesting use cases that approach the problem of data interoperability of the ocean data ecosystem by implementing different approaches such as cloud, developing a new ocean data platform (e.g. Hub Ocean), ai solutions for data interoperability (e.g. ODINI) etc.

Section 3.4 Data Sources and Product Offering, is difficult to follow given the order in which things are presented and the language of categories not being consistent. Section 3.4 outlines three categories of data sources (raw source, repository or portal) but the following sub-section doesn’t seem to follow these. E.g., Section 3.4.1 WOD, the data source category chosen is not one detailed in the paragraph above. Consistent language needs to be used. Same goes for Section 3.4.6 CMEMS. Section 3.4 is also in a different order to what is presented in Figure 2.

Answer: The data sources described in section 3.4 are organized according to the three infrastructural approaches distinguishing them, namely centralized, distributed, federated. For each approach we provide several representative examples. This rationale is now explicitly represented in Fig. 4, which summarizes the ocean data sources described in section, emphasizing their are organization according to their infrastructural approach. To further improve the clarity of this section, the following text was added (lines 486 - 487): “Here we categorize the different data sources by their infrastructural approach, as defined in section 2.1, namely: centralized, federated, and distributed data ecosystems. We now give an overview on some of the major data sources (Fig. 4).”

Specific Comments:

Figure 1. The description provided in the text is great but the figure does not convey anything and seems redundant. I suggest removing this figure from the manuscript.

Answer: We agree with the reviewer and have removed the figure from the revised version of the manuscript.

Terminologies and language varies throughout the manuscript. Consistent use of terminologies and language is highly recommended.

Answer: we have done a thorough reading of the manuscript, correcting inconsistencies and terminology differences.

Section 4 starts with a sentence saying there are 3 main concepts for a data ecosystem, yet the beginning of the paper clearly outlines 4 main concepts. This section should also move earlier in the paper such as before section 3 as it provides the overview components of the data ecosystem being presented in this manuscript.

Answer: The notion of 3 main concepts is erroneous, and was corrected to 4 main concepts. While we understand the rationale of placing the section on roles in the ecosystem (section 4), prior to the section on Modelling and mapping the ocean data ecosystem (section 3), we think the order fits better, as section 4 cites information presented in section 3.

Lines 102-103. Having specific examples of organisations that adhere to each centralized, federated or distributed data ecosystems might be helpful for readers to understand this. Or use words other than those in the architecture titles to describe them (e.g., not using centrally to describe a centralised ecosystem).

Answer: as noted above, the data source examples are now aligned according to these categories and are further exemplified in section 3. Furthermore, we refined the definition In line 104, and removed the redundant definition in section 5.

Line 124-132: This sentence is very long, complex and hard to follow. Please break into multiple sentences to make it clearer to the reader.

Answer: The sentence has been rephrased as follows: “A comprehensive overview of the ocean data sector has been provided by Tanhua et al., (2019a, 2019b, 2021), who reviewed recent developments in the technical capacity and requirement setting for a data management system in the frame of the Global Ocean Observing System (GOOS). These papers emphasize the importance of well-managed data management systems for ensuring the data collected by the ocean observing systems are accessible for current and future uses.”.

Technical Corrections:

An overall copy-edit of the paper is needed to improve grammar, check for missing or additional spaces before/after brackets, inconsistent capitalisation etc.

Answer: grammar and editing errors were corrected throughout the text.

“The concept of a data ecosystem in ocean research” header on line 114 needs to be numbered.

Answer: The following headers were added to section 2 and numbered:  

2.1 Data ecosystem general definitions and examples (line 75)

2.2   The concept of a data ecosystem in ocean research (line 111) 

Figures 2 & 3. Any acronyms provided in the figures need to be described in the figure heading.

Answer: where appropriate acronym description was added to the figure captions

Section 3.2.2 Key Initiatives needs to have its own header. The header cannot be part of the first sentence of the paragraph. Same goes for section 3.2.3, Section 3.2.4, and Section 3.4.10.

Answer: headers were added accordingly.

Throughout there are bolded headers without numbers, this may be due to the journal requirements but this make it difficult to read. These either need to be numbered and have appropriate headers keeping the formatting of the rest of the paper, or have the bolded format of the text be removed. Lines 427, 435, 447, 461, 490, 510, 527, 612, 637, 648, 686, 714, 746, 823, 828, 834, 855, 862, 868, 886, 900, 903.

Answer: bold headers have been removed throughout the text.

We thank you for your kind and encouraging comments, and we are grateful to both reviewers for their thoughtful and constructive feedback. We are currently working intensively on revising the manuscript in line with their suggestions, and will submit a revised version shortly.