Large parts of the oceans – particularly the deep sea as well as tropical and polar regions – have only been poorly explored to date. In a study published today in the journal “Nature Communications,” Senckenberg researcher PD Dr Hanieh Saeedi analyzed approximately 48 million occurrence data records covering more than 184,000 marine species – the world’s first assessment of depth-explicit assessments of marine biodiversity patterns and their drivers at this resolution. The study shows that more than half of the world’s oceans have barely been recorded scientifically. For example, less than 2.5 percent of all biodiversity data originates from the central tropics. The results underscore the need for internationally coordinated research and data collection and digitisation, as well as long-term monitoring programs to protect marine ecosystems.
Oceans cover more than 70 percent of the Earth’s surface and form the world’s largest contiguous ecosystem. Not only are they home to an enormous diversity of organisms, but they also play a central role in the global climate system and oxygen production. “Despite their tremendous importance – including for us humans – the oceans remain vastly under-explored. Based on estimates, there are over 2.2 million marine species, yet about 90 percent of these have not yet been scientifically described,” explains PD Dr. Hanieh Saeedi, Head of the Geobiodiversity Information and Data Management Division at the Senckenberg Research Institute and Natural History Museum in Frankfurt, and she continues, “Despite decades of research and extensive data collection, our knowledge of global marine biodiversity remains distorted and incomplete. Where are the hotspots of marine biodiversity? Where are the gaps in our knowledge? And what are the drivers of biodiversity?”
To find answers to these questions, the Senckenberg data specialist analyzed approximately 48 million data records on the occurrence of marine organisms in her new study. These data come from global, freely accessible databases such as the Ocean Biodiversity Information System (OBIS) and the Global Biodiversity Information Facility (GBIF). In total, the data set contains information on over 184,000 marine species. “This corresponds to about 90 percent of the scientifically described and accepted marine fauna. The goal was to provide the first global picture of marine biodiversity at this scale – not only to identify distribution patterns, but also to systematically highlight obvious gaps in the data and determine which factors influence these patterns. This is also crucial for the planning of targeted conservation measures within the framework of the UN Decade of Ocean Science,” adds Saeedi, explaining her approach.
The analysis includes data ranging from shallow coastal waters to extreme depths of around 11,000 meters. In addition, statistical methods were used to account for biases caused by uneven sampling. “This is the first global assessment of marine based on such an extensive dataset, analysing biodiversity patterns and their drivers across the full depth gradient – from the water’s surface down to the deep sea. The differences between the varying depth levels and animal groups were also systematically taken into account,” says Saeedi.
The marine scientist’s findings are alarming: More than half of the world’s oceans have not been adequately explored, or the data were not made publicly available, meaning that large parts of the oceans are virtually “invisible.” This is particularly evident in the deep sea: Practically no usable biodiversity data exist for more than 160 million square kilometers below a depth of 200 meters. Saeedi comments, “At the same time, the results show that biodiversity in the deep sea is likely significantly higher than previously assumed. Tropical and polar regions are also severely under-surveyed, even though they potentially host a large number of species.”
Less than 2.5 percent of all data sets originate from the central tropics, including African marine regions. The situation is different in economically well-developed regions, such as the North Atlantic, and in shallow marine areas down to a depth of about 200 meters, for which a concentration of data exists. “This uneven distribution means that certain patterns of biodiversity may be distorted. In some cases, hotspots are underestimated or not recognized at all, particularly in the deep sea and other under-explored regions,” Saeedi points out.
The drivers of biodiversity – i.e., the factors that influence how many species are present in an area and how biodiversity develops or changes – can also not be standardized across the world’s oceans. Saeedi’s study shows that in shallow marine areas, water temperature, in particular, plays a key role in biodiversity. In deeper ocean regions, nutrient cycles and human activities are more decisive. According to the researcher, this is likely also due to the fact that previous scientific deep-sea expeditions only focused on specific regions.
“The findings come at a critical juncture for global ocean policy, as governments pursue ambitious biodiversity conservation goals under the UN Decade of Ocean Science and international marine conservation agreements. Conservation planning based on incomplete and geographically biased data can result in particularly vulnerable ecosystems remaining ‘invisible’ to science and policymakers. You cannot effectively protect what has never been sampled, documented, or digitally recorded,” warns Saeedi, and she continues, “My study shows that the global picture of marine biodiversity continues to be heavily influenced by where researchers have taken samples and published data in the past, rather than by the actual distribution of life in the ocean. To close existing knowledge gaps, significant international investment is needed – for example, in long-term monitoring programs, targeted deep-sea expeditions, standardized data collection, the large-scale digitization and integration of biodiversity data, and more closely coordinated international research collaborations. Only in this way can the actual diversity of life in the oceans be realistically assessed and effectively protected.”
Publication: Saeedi, H. Gaps and drivers of global marine animal biodiversity from the surface to abyss. Nat Commun 17, 4553 (2026). https://doi.org/10.1038/s41467-026-73613-z
Oceans cover more than 70 percent of the Earth’s surface and form the world’s largest contiguous ecosystem. Not only are they home to an enormous diversity of organisms, but they also play a central role in the global climate system and oxygen production. “Despite their tremendous importance – including for us humans – the oceans remain vastly under-explored. Based on estimates, there are over 2.2 million marine species, yet about 90 percent of these have not yet been scientifically described,” explains PD Dr. Hanieh Saeedi, Head of the Geobiodiversity Information and Data Management Division at the Senckenberg Research Institute and Natural History Museum in Frankfurt, and she continues, “Despite decades of research and extensive data collection, our knowledge of global marine biodiversity remains distorted and incomplete. Where are the hotspots of marine biodiversity? Where are the gaps in our knowledge? And what are the drivers of biodiversity?”
To find answers to these questions, the Senckenberg data specialist analyzed approximately 48 million data records on the occurrence of marine organisms in her new study. These data come from global, freely accessible databases such as the Ocean Biodiversity Information System (OBIS) and the Global Biodiversity Information Facility (GBIF). In total, the data set contains information on over 184,000 marine species. “This corresponds to about 90 percent of the scientifically described and accepted marine fauna. The goal was to provide the first global picture of marine biodiversity at this scale – not only to identify distribution patterns, but also to systematically highlight obvious gaps in the data and determine which factors influence these patterns. This is also crucial for the planning of targeted conservation measures within the framework of the UN Decade of Ocean Science,” adds Saeedi, explaining her approach.
The analysis includes data ranging from shallow coastal waters to extreme depths of around 11,000 meters. In addition, statistical methods were used to account for biases caused by uneven sampling. “This is the first global assessment of marine based on such an extensive dataset, analysing biodiversity patterns and their drivers across the full depth gradient – from the water’s surface down to the deep sea. The differences between the varying depth levels and animal groups were also systematically taken into account,” says Saeedi.
The marine scientist’s findings are alarming: More than half of the world’s oceans have not been adequately explored, or the data were not made publicly available, meaning that large parts of the oceans are virtually “invisible.” This is particularly evident in the deep sea: Practically no usable biodiversity data exist for more than 160 million square kilometers below a depth of 200 meters. Saeedi comments, “At the same time, the results show that biodiversity in the deep sea is likely significantly higher than previously assumed. Tropical and polar regions are also severely under-surveyed, even though they potentially host a large number of species.”
Less than 2.5 percent of all data sets originate from the central tropics, including African marine regions. The situation is different in economically well-developed regions, such as the North Atlantic, and in shallow marine areas down to a depth of about 200 meters, for which a concentration of data exists. “This uneven distribution means that certain patterns of biodiversity may be distorted. In some cases, hotspots are underestimated or not recognized at all, particularly in the deep sea and other under-explored regions,” Saeedi points out.
The drivers of biodiversity – i.e., the factors that influence how many species are present in an area and how biodiversity develops or changes – can also not be standardized across the world’s oceans. Saeedi’s study shows that in shallow marine areas, water temperature, in particular, plays a key role in biodiversity. In deeper ocean regions, nutrient cycles and human activities are more decisive. According to the researcher, this is likely also due to the fact that previous scientific deep-sea expeditions only focused on specific regions.
“The findings come at a critical juncture for global ocean policy, as governments pursue ambitious biodiversity conservation goals under the UN Decade of Ocean Science and international marine conservation agreements. Conservation planning based on incomplete and geographically biased data can result in particularly vulnerable ecosystems remaining ‘invisible’ to science and policymakers. You cannot effectively protect what has never been sampled, documented, or digitally recorded,” warns Saeedi, and she continues, “My study shows that the global picture of marine biodiversity continues to be heavily influenced by where researchers have taken samples and published data in the past, rather than by the actual distribution of life in the ocean. To close existing knowledge gaps, significant international investment is needed – for example, in long-term monitoring programs, targeted deep-sea expeditions, standardized data collection, the large-scale digitization and integration of biodiversity data, and more closely coordinated international research collaborations. Only in this way can the actual diversity of life in the oceans be realistically assessed and effectively protected.”
Publication: Saeedi, H. Gaps and drivers of global marine animal biodiversity from the surface to abyss. Nat Commun 17, 4553 (2026). https://doi.org/10.1038/s41467-026-73613-z
