Characterising the global distribution, composition and relationship of species occurring in chemosynthesisbased-ecosystems (CBEs) at both global and regional scales will rapidly advance theoretical research and conservation efforts. The most recent data compilation on the distribution of species occurring on hydrothermal vents, cold seeps and organic remains (ChEssBase) was updated in 2010, and since then only sporadic updates have been made. Here, we propose building a new global, open-source and up-to-date database, MACROCHESS, incorporating over a decade of new discoveries and the most recent taxonomic knowledge, which would be integrated and connected with InterRidge Vents Database, sFDvent, WoRMS and OBIS. Such data would enable the exploration of an array of research avenues, such as investigating i) the response of CBEs to environmental change and human disturbance, ii) the impacts of biodiversity loss on the ecosystem services provided by CBEs and iii) clues as to the evolution of species occurring at CBEs.

This knowledge is particularly crucial for understanding the connectivity and resilience of these ecosystems and is important for the development of sound management measures in the context of our changing oceans and with the accelerating interest in mining hydrothermal vents. MACROCHESS will advance the field of hydrothermal vent research significantly, since current biogeographical delineations of vent communities tend to exclude the distributions of species in other CBEs, despite a consensus that many species have overlapping distributions across all three types of CBEs and species may use different chemosynthetic habitats as stepping stones for connectivity. Furthermore, many modern hydrothermal vent studies only utilise the most wellstudied taxonomic groups and/or focus on local or regional scales. This approach limits and biases our understanding of where CBE species occur and, consequently, of the dispersal pathways and topographic barriers, which are considered to play major roles in the conservation and resilience of hydrothermal vents. This new database will enable an array of spatial and temporal macroecological studies that have great potential to guide the development and management of deep-sea marine protected areas. This new database can also be utilised in guiding future research efforts as it will reveal, in a systematic manner, many of the biases underpinning hydrothermal vent and other CBE research and will function as a unified platform for depositing species data.

The main objectives of this WG are:

1. Compline an open-source global database, MACROCHESS, with species distribution records of meio-, macro- and megafuana occuring on CBEs. 
2. Produce a user-friendly product that serves as a platform for conceiving, strategising and guilding future international research efforts, collaborations, management and conservation of hydrothermal vents.
3. Encourage and support the sharing and deposition of open-source data for CBEs in order to improve conservation efforts of vents. 
4. Enable and perform an array of large-scale analyses with the aim of improving our understanding of vents and other CBEs. 

There are four distinct phases in the construction of MACROCHESS:

1. The initial data compilation will be based on extracting species distribution data and recording bibliographical references from ChEssBase, sFDVent and OBIS databases. These records will be further complemented by reviewing the literature, such as the recent cruise report compilation accomplished by Thaler et al. (2019) encompassing references and data from 262 research expeditions to hydrothermal vent sites. The InterRidge Vent Database will also be utilized for location data and useful references to identify potential sources for biological data.  
2. The working group members will submit data they have access to, while the wider scientific community will have the opportunity to engage and submit data through a call utilising the INDEEP, DOSI and InterRidge mailing lists through Google Sheets. The database will also be announced and introduced during the 7th International Symposium on Chemosynthesis-Based Ecosystems.
3. The workshops will bring together the experts from the working groups and from the wider community and provide a platform for: i) discussing the problematic taxa; ii) reviewing and reaching consensus on the taxonomic units; iii) identifying the geographical and taxonomical gaps; and iv) sharing ideas on the design of the database. These workshops will take place in Aveiro, Portugal in early 2021 and another location in early 2022 over the course of three to four days.
4. Converting all the data entries into a unified database through multiple iterations of processing, cleaning and conducting quality control using free open-source software such as OpenRefine and R environment. The format of the database will consist of approximately 40 entry fields, which will revolve around the species, location, environmental data and information on the ownership of the data, thus ensuring the usefulness of the database beyond the immediate analyses that it will be utilised for. In order to facilitate the long-term maintenance of MACROCHESS, its fields will be aligned as closely as possible to existing databases (i.e., OBIS, sFDvent, InterRidge Vents Database), using existing controlled vocabularies and the taxonomic naming authority that is used by OBIS (WoRMS).

1. An open-source database for the global distribution of species in CBEs
2. The creation and consolidation, through two workshops and video conferences, of a wide and dynamic scientific working group to input data, discuss problematic taxa and review and reach consensus on the taxonomic units and share ideas on the database
3. A publication introducing, describing and promoting the database enabling future cohesive macroecological analyses of chemosynthesis-based ecosystems
4. A high-profile peer-reviewed publication delineating a global biogeographical scheme for vents and other chemosynthesis-based ecosystems
5. Protocol on updating MACROCHESS for long-term maintenance of the database beyond the project period. There will be a section advising on how to submit future data to OBIS/ sFDvent tagged for future inclusion in MACROCHESS to facilitate producing subsequent versions of the database.

This WG contributes towards the principles of InterRidge by promoting and coordinating international interdisciplinary scientific exchange and encouraging conservation and management of oceanic ridge habitats. The activities and outputs of this WG are integrated within the themes of InterRidge’s Third Decadal Plan, section “Past, Present, and Future of Vent Ecosystems”, where MACROCHESS data is essential in addressing the knowledge gaps identified, such as assessing resilience to past and future global environmental changes and deep-sea mining. Furthermore, MACROCHESS is complementary to the InterRidge Vents database, which is a widely recognised tool utilised for a variety of scientific activities and environmental assessments. MACROCHESS has the potential to become an equally crucial component of InterRidge by contributing information towards biodiversity assessments and conservation scenarios linked to the intense exploration efforts of Mid-Ocean ridges (MOR) and volcanic arcs and back-arc spreading systems (ABA).

The members of the working group represent experts working in hydrothermal vents, seeps and organic remains across a wide variety of disciplines (morphological and molecular taxonomy, phylogenetics, population genetics, physiology, organismal biology, ecology, biogeography and data management) and geographic regions. The participants represent nine countries from four continents with access to data from different ocean basins. The working group has four early career researchers with two years of post-PhD experience from Norway, France and USA, while the other members are at various stages of their careers. Collaborations with other programs and databases such as InterRidge Vents Database (Dr. Stace Beaulieu, Woods Hole Oceanographic Institution, USA), sFDvent (Dr. Abbie Chapman and Dr. Amanda Bates) and ChEssBase (Dr. Eva Ramirez-Llodra) are ensured by engaging these researchers in the working group. The “Other members” are researchers who have expressed interest in participating in the creation and design of the database through pre-existing collaborations and/or by submitting data. The working group welcomes further suggestions from the Steering Committee for representatives from China, Korea and India.