Assessing indirect biodiversity conservation benefits of fisheries closures in the Gulf of St. Lawrence, Canada

concentration, and bottom pH, that may threaten life history dynamics and early-life stage development of the three focal species and highlight climate vulnerability of the region, its spe- cies, and the continuing provision of indirect BCBs. Current and future provisioning of biodiversity conservation benefits (BCBs) The main purpose of OECMs is to provide long-term BCBs. While BCBs are the cornerstone of OECM objectives globally, research on indirect BCBs of coral and sponge OECMs across Canada remains limited [9]. Assessing BCBs of OECMs through data and knowledge synergy brings needed insights in terms of these OECM outcomes. Through integrating different assessments of potential Atlantic halibut, Greenland halibut, and redfish spawning sites in the Gulf of St. Lawrence, we documented current indirect BCBs of the existing OECMs in the region. The existence of these indirect BCBs is further supported by the underlying habitat. All OECMs in the Gulf of St. Lawrence are protecting benthic habitats under DFO’s Sensitive Ben- thic Areas Policy and include sensitive cold-water coral and sponge aggregations. Cold-water corals and sponges create habitat for numerous marine species, particularly in regions without natural geographic features that offer structure for fish and invertebrates, such as the Gulf and the Laurentian Channel more specifically [10]. The structures formed by corals and sponges Fig 4. Mid-century percent change in bottom sea temperature, bottom oxygen concentration and pH for individual Other Effective area-based Conservation

Measures (OECMs) and associated average depth (m) of each OECM. Changes represent values in 2050–2059 relative to the baseline time frame 2010–2019. Labels indicate whether an OECM is overlapping with potential spawning habitat of AH = Atlantic halibut, GH = Greenland halibut, and RF = redfish. Error bars indicate one standard deviation of the mean. Values for end-century changes are in S4 Fig. https://doi.org/10.1371/journal.pone.0316754.g004 PLOS ONE Indirect biodiversity conservation in the Gulf of St. Lawrence PLOS ONE | https://doi.org/10.1371/journal.pone.0316754 January 9, 2025 10 / 20