Open-Source Marine Biodiversity Data Quality in the Norwegian Sea Spanning 149 Years: Knowledge Gaps in the Deep-Sea Mining Opening Area.

This work identifies spatial-temporal patterns of marine species biodiversity in the Norwegian, Greenland and Barents Seas and provides specific information in Norway for Environmental Impact Assessments and Statements about area-based indices for biodiversity. The opening of the Norwegian Extended Continental Shelf for deep-sea mining is a currently relevant topic for environmental management, as strategies to minimize mining impacts and delimit key zones for ecological preservation have been widely advised. A quality control procedure covering temporal and spatial scales on open-source biodiversity data was applied, including the compilation of marine species from the archives of the Norwegian North-Atlantic Expedition 1876-1878. Here, we present biodiversity patterns for 10,505,496 marine occurrences from 1876 to 2025 (149 years). Data occurrences were classified into two main datasets (shallow, < 500 m and deep ≥ 500 m) and two sub-datasets for each (planktonic and benthic). 97% of the total were classified in the first main and 3% in the second main. On map view and out of 122,955 grid cells, 32,274 and 15,528 encompass data from the shallow and deep datasets, respectively, with different degrees of coverage inside; most frequently, grid cells with 1 to 10 occurrences. Data is mainly planktonic (20,098 grid cells for shallow-planktonic and 3127 grid cells for deep-planktonic). Peaks of species richness occur from southern to northern latitudes, even with evidently reduced values for species occurrences and abundances at certain latitudes. We conclude that knowledge gaps of benthic biodiversity in the Norwegian deep-sea mining opening area are huge. The cumulative curve of species richness reveals that species identities, included in deep-sea data, are not sufficient to quantify area-based biodiversity indices in the species pool. Our findings are congruent with the need to contemplate data from deeper areas for decision-making at different spatial-temporal windows, especially considering the granting of deep-sea mining licenses.