El mar profundo argentino: nueva frontera estratégica para el desarrollo sustentable

Deep sea is the largest and likely the most biologically diverse ecosystem of the world, but it is also the most unknown. The Mediterranean Sea (< 1% of the ocean surface and contains only the 0.3% of its volume) is a hot spot of marine biodiversity containing ca 7.5% of the world marine biodiversity, associated with a multitude of habitats spreading from the coast to its dark portion (e.g., coral banks, seamounts, canyons, and hydrothermal vents). Its deep-sea ecosystems are increasingly subjected to direct anthropogenic impacts (including overfishing, chemical pollution, dumping, litter, and plastics), which are often over-imposed to the increasing effects of global change. Here, are illustrated the expected impacts of shifts in the main variables such as temperature, food supply, pH, and oxygen on the deep Mediterranean Sea ecosystems. One of the most consequences is related to shifts in the quality and quantity of the inputs of organic matter to the deep seafloor. The deep Mediterranean Sea is far more oligotrophic than other oceans at equal depths, and although deep-sea biota reacts to food shortage by increasing their efficiency in its use, a decrease in food availability can have dramatic effects on its food webs. The deep Mediterranean Sea is showing a clear rise of deep-water temperatures. In the last decades, deep-water warming is accelerating at unprecedented rates, causing a significant shift in biodiversity even for variations in the order of 0.1 °C. Higher temperatures increase deep-sea metabolism, thus exacerbating the effects of food limitation. Moreover, ocean acidification reduces the calcification capacity of corals and alters their metabolism. Although it can be expected that increasing temperatures might increase the potential spread of oxygen minimum zone, so far, only hypoxic events were reported in Mediterranean Sea. The analysis of potential ecosystem vulnerability indicates that the ecosystems that are most sensitive to global change are deep-water coral systems and deep-sea plains. In addition, deep-sea canyons are also likely increasingly subjected to physical disturbance as a result of the increase in the frequency and intensity of climate-driven episodic events. Available information also suggests that biodiversity and ecosystem functioning of the deep Mediterranean Sea is undergoing dramatic changes, which result in accelerated organic matter biogeochemical cycling, miniaturization of the organisms’ size, increased metabolism, dominance of the microbial components, and mortality rates of deep-sea biota. Given the high sensitivity of the Mediterranean Sea to global change in comparison with other oceanic regions, and the vulnerability of its deep-sea habitats/ecosystems, specific policy measures are needed to protect its biodiversity, restore damaged habitats, and increase deep-sea ecosystems resistance and resilience to the ongoing impacts of global change.

The goal of this paper is to review current impacts of human activities on the deep-sea floor ecosystem, and to predict anthropogenic changes to this ecosystem by the year 2025. The deep-sea floor ecosystem is one of the largest on the planet, covering roughly 60% of the Earth's solid surface. Despite this vast size, our knowledge of the deep sea is poor relative to other marine ecosystems, and future human threats are difficult to predict. Low productivity, low physical energy, low biological rates, and the vastness of the soft-sediment deep sea create an unusual suite of conservation challenges relative to shallow water. The numerous, but widely spaced, island habitats of the deep ocean (for example seamounts, hydrothermal vents and submarine canyons) differ from typical deep-sea soft sediments in substrate type (hard) and levels of productivity (often high); these habitats will respond differently to anthropogenic impacts and climate change. The principal human threats to the deep sea are the disposal of wastes (structures, radioactive wastes, munitions and carbon dioxide), deep-sea fishing, oil and gas extraction, marine mineral extraction, and climate change. Current international regulations prohibit deep-sea dumping of structures, radioactive waste and munitions. Future disposal activities that could be significant by 2025 include deep-sea carbon-dioxide sequestration, sewage-sludge emplacement and dredge-spoil disposal. As fish stocks dwindle in the upper ocean, deep-sea fisheries are increasingly targeted. Most (perhaps all) of these deep-sea fisheries are not sustainable in the long term given current management practices; deep-sea fish are long-lived, slow growing and very slow to recruit in the face of sustained fishing pressure. Oil and gas exploitation has begun, and will continue, in deep water, creating significant localized impacts resulting mainly from accumulation of contaminated drill cuttings. Marine mineral extraction, in particular manganese nodule mining, represents one of the most significant conservation challenges in the deep sea. The vast spatial scales planned for nodule mining dwarf other potential direct human impacts. Nodule-mining disturbance will likely affect tens to hundreds of thousands of square kilometres with ecosystem recovery requiring many decades to millions of years (for nodule regrowth). Limited knowledge of the taxonomy, species structure, biogeography and basic natural history of deep-sea animals prevents accurate assessment of the risk of species extinctions from large-scale mining. While there are close linkages between benthic, pelagic and climatic processes, it is difficult to predict the impact of climate change on deep-sea benthic ecosystems; it is certain, however, that changes in primary production in surface waters will alter the standing stocks in the food-limited, deep-sea benthic. Long time-series studies from the abyssal North Pacific and North Atlantic suggest that even seemingly stable deep-sea ecosystems may exhibit change in key ecological parameters on decadal time scales. The causes of these decadal changes remain enigmatic. Compared to the rest of the planet, the bulk of the deep sea will probably remain relatively unimpacted by human activities and climate change in the year 2025. However, increased pressure on terrestrial resources will certainly lead to an expansion of direct human activities in the deep sea, and to direct and indirect environmental impacts. Because so little is known about this remote environment, the deep-sea ecosystem may well be substantially modified before its natural state is fully understood.

With ongoing climate change, multiple stressors including ocean warming, deoxygenation, ocean acidification and limited nutrient availability will lead to large regime shifts within marine ecosystems[1]. Deep-sea ecosystems are adapted to the stable ambient conditions of the deep ocean and are therefore likely highly vulnerable to human impacts and climate change. Future projections show considerable deep-water warming, acidification, and heat accumulation, and moreover, in strong overshoot scenarios, irreversibility is found in various properties in the deep ocean[2]. Here, we compare rates of warming, acidification, and deoxygenation at depth and the seafloor for a range of emission driven idealized overshoot scenarios run with the fully coupled Norwegian Earth System Model version 2 (NorESM2). We discuss the impact that changing ambient conditions have for deep sea ecosystems at the example of Lophelia Pertusa, a common cold-water coral found in the North Atlantic. The continued exposure to calcium carbonate undersaturation and inhibited aerobic activity due to warming and deoxygenation lead to physiologically unsustainable conditions for cold water corals, which could be alleviated by sustained food supply, i.e., increased export production. We therefore conclude by showing different potential habitat extents in relation to environmental stressors under different evolving climates.&amp;#160;We acknowledge the project TipESM &amp;#8220;Exploring Tipping Points and Their Impacts Using Earth System Models&amp;#8221;. TipESM is funded by the European Union. Grant Agreement number: 101137673. DOI: 10.3030/101137673. &amp;#160;[1] Heinze et al., 2020, The quiet crossing of tipping points, PNAS, 118(9)[2] Schwinger et al., 2022, Emit now, mitigate later? Earth system reversibility under overshoots of different magnitudes and durations, Earth Syst. Dynam., 13, 1641&amp;#8211;1665

Environmental viromes reveal the global distribution signatures of deep-sea DNA viruses

The deep sea, the largest ecosystem on Earth and one of the least studied, harbours high biodiversity and provides a wealth of resources. Although humans have used the oceans for millennia, technological developments now allow exploitation of fisheries resources, hydrocarbons and minerals below 2000 m depth. The remoteness of the deep seafloor has promoted the disposal of residues and litter. Ocean acidification and climate change now bring a new dimension of global effects. Thus the challenges facing the deep sea are large and accelerating, providing a new imperative for the science community, industry and national and international organizations to work together to develop successful exploitation management and conservation of the deep-sea ecosystem. This paper provides scientific expert judgement and a semi-quantitative analysis of past, present and future impacts of human-related activities on global deep-sea habitats within three categories: disposal, exploitation and climate change. The analysis is the result of a Census of Marine Life – SYNDEEP workshop (September 2008). A detailed review of known impacts and their effects is provided. The analysis shows how, in recent decades, the most significant anthropogenic activities that affect the deep sea have evolved from mainly disposal (past) to exploitation (present). We predict that from now and into the future, increases in atmospheric CO2 and facets and consequences of climate change will have the most impact on deep-sea habitats and their fauna. Synergies between different anthropogenic pressures and associated effects are discussed, indicating that most synergies are related to increased atmospheric CO2 and climate change effects. We identify deep-sea ecosystems we believe are at higher risk from human impacts in the near future: benthic communities on sedimentary upper slopes, cold-water corals, canyon benthic communities and seamount pelagic and benthic communities. We finalise this review with a short discussion on protection and management methods.

Technological improvements have significantly shifted our fundamental knowledge of the ocean, particularly the deep sea. However, the lack of cost-effectiveness and accessibility in technologies remains a limiting factor in our scientific understanding of the deep ocean. Research vessels have traditionally served as the primary platforms for ocean observations, particularly deep-sea ecosystems. These vessels are equipped to deploy various instruments, including autonomous and tethered robots, to observe biological, chemical, and physical components of the deep ocean.Despite the progress made, traditional and contemporary tools still suffer from several limitations. While these tools have enhanced our understanding, more precise mapping of small-scale topography and its role in creating ecological heterogeneity has exposed significant geographical and knowledge gaps. The geographic scope of large-scale research is primarily restricted to the North Pacific and Atlantic Oceans, leading to the undersampling of other regions of the world’s ocean. Although current deep-sea robots enable finer-scale observations, they have limited flexibility, autonomy, and operational depth. Deep-sea operations have prohibitively high-cost barriers, in part due to the high cost for procurement for instrumentation and deployment (i.e., vessel time). Despite over 200 years of oceanographic research, several key interdisciplinary questions about the deep-sea remain unresolved: (1) How many organisms live in the ocean? (2) Who they are? (3) What ecosystem services do they provide? (4) How do the ocean’s various components interact?For more accurate and comprehensive observations of the ocean, we will build off the momentum for low-cost alternatives to deep-sea instrumentation for regular ocean sampling by proposing a technological roadmap. This includes developing a roadmap with initiatives such as "Shipboard Technology Excellence Procedures" and tech-based decision guides tailored to the available equipment, and a repository of all associated standard operating procedures. We also propose concrete actions to improve capacity building across institutions and nations through FAIR collaborations. For instance, establishing local groups to coordinate efforts and train members, alongside a global organizing body, could facilitate the tracking of samples, projects, and personnel to streamline sampling and analysis. Finally, we outline a series of actions aimed at bridging the gaps between science, policy, and society to ensure the benefits of deep-sea research extend beyond the scientific community.

Given the extensive impact of human activities on the marine environments during the last decades (e.g. climate warming, pollution, and habitat degradation), remote areas such as the little-explored deep-sea ecosystems need protection and long-term stewardship of their goods and services. Deep-sea ecosystems play a crucial role in global ecological balance by connecting with shallow-water and continental productivity, mirroring humanity&amp;#8217;s increasing dependence on ecosystem services at both, local and global scales. Therefore, to foster a sustainable future, it is essential to educate younger generations about their connection to ecosystems that extend beyond local geographies, e.g. deep-sea biome, its resources, and its services. This can raise awareness about our global limits to growth and inspire a commitment to protecting the legacy of pristine environments.To address this need, I developed a project with my students to explore humanity&amp;#8217;s connections to the deep-sea environment. The project aimed to examine the fundamental components and processes that govern deep-sea ecosystems (biological, chemical, physical), and their links to cultural and economic interests (e.g. scientific research, archaeology, deep-sea mining). Students were trained to use Google Earth, GIS resources, data repositories, and virtual imagery to investigate the biodiversity of deep-sea ecosystems in a dynamic and changing ocean environment. They analyzed distribution patterns and assessed the impacts of pollution and global warming on these ecosystems.The project included independent research, group collaborations, and hands-on tasks focused on marine biodiversity distribution, endangered species, habitat conservation, and the effects of ocean pollution and climate warming on deep-sea life. Students were encouraged to use critical thinking to analyze data, make predictions, create graphs, and draw inferences on the probability of endangered species' short and long-term survival. Students became familiar with the methods and technology used in deep-sea exploration and collaborated effectively to propose innovative solutions to environmental challenges. This multidisciplinary approach integrated knowledge from biology, chemistry, physics, geography, and math with creative activities like role-playing, drawing, 3D modeling, and designing informational leaflets. These activities illustrated humanity&amp;#8217;s connection to the deep sea, even in areas far from coastlines.To enhance their communication skills, students used Canva and Prezi platforms to create engaging presentations. They also developed artistic outputs such as posters, leaflets, and models, and engaged in scratch coding and role-playing activities. Knowledge assessments involved students presenting their findings to peers, emphasizing soft skills like public speaking and collaboration. Projects were evaluated based on the accuracy of scientific information, creativity, originality, and potential community impact. The initiative culminated in a showcase event, where parents, friends, and peers reviewed the students' work and participated in discussions. This experience not only deepened students&amp;#8217; understanding of human-driven impacts on deep-sea ecosystems but also equipped them with the skills to become informed advocates for environmental stewardship.

Chapter One - Temporal Change in Deep-Sea Benthic Ecosystems: A Review of the Evidence From Recent Time-Series Studies

Environmental viromes reveal global virosphere of deep-sea sediment RNA viruses

Towards an Ecosystem-Based Marine Spatial Planning in the deep Mediterranean Sea.

Trophic model of a deep-sea ecosystem with methane seeps in the South China Sea

The urbanization, the rising of the population, the development of technology along with the elevating level of our everyday lives increase the need for mineral resources, which have multiple appliances. Until now, such deposits were found in terrestrial sites, which however, will soon expire. Therefore, the deep sea mining could be the solution to cover humanity’s needs. However, the limited knowledge on deep sea ecosystems and restricted environmental baseline information currently available are prohibiting to move towards the mining of deep-sea resources, as serious harm can be caused to the environment. As the sea has no boundaries, mining activities can have impacts in various places and users of the marine area. To date, only test mining and exploration activities have taken place worldwide, without however moving to the next phase, which is the exploitation of the available deposits. The Authority which regulates the deep-sea area (meaning the marine area beyond national jurisdiction) is the International Seabed Authority which, via a set of regulations and various recommendations and guidelines, controls the mining activities in the deep sea. The International Seabed Authority supports that the activities should take place basis a precautionary approach, adaptive management and to conduct Environmental Impact Assessment and Environmental Management Plans, as the goal is to proceed with mining in the future, but in a sustainable manner, to protect the deep sea environment for our sake and the generations to come. Through studying the case of Clarion- Clipperton Fracture Zone, one of the areas with growing interest for its mining due to high concentration in polymetallic nodules, it has become apparent that the scientific knowledge is still limited, and it is the needful factor to address environmental thresholds in order to proceed with the mining phase. By raising scientific knowledge, and understanding the ecosystems and their connectivity, the environmental thresholds can be managed and understood, in order to avoid irreversible environmental harm.

The size of the deep sea and the sub-seabed biosphere makes deep-sea ecosystems an enormous reservoir of biomass on Earth. As depth increases, the larger benthic components (that is, megafauna) as well as the abundance and biomass of macrofauna, meiofauna, and microbes tend to decrease. At bathyal-abyssal depths, microbial components — mostly Bacteria and Archaea — therefore account for most of the biomass. The microbial processes occurring in the deep ocean provide essential services by driving nutrient regeneration and global biogeochemical cycles necessary for sustaining the primary and secondary production of the oceans. This chapter focuses on biodiversity and ecosystem functioning in the deep ocean. It provides an overview of deep-sea ecosystems and discusses the various approaches used to investigate deep-sea biodiversity and ecosystem functioning. It also considers functional diversity in the deep ocean.

Viruses are the most abundant biological organisms of the world's oceans. Viral infections are a substantial source of mortality in a range of organisms-including autotrophic and heterotrophic plankton-but their impact on the deep ocean and benthic biosphere is completely unknown. Here we report that viral production in deep-sea benthic ecosystems worldwide is extremely high, and that viral infections are responsible for the abatement of 80% of prokaryotic heterotrophic production. Virus-induced prokaryotic mortality increases with increasing water depth, and beneath a depth of 1,000 m nearly all of the prokaryotic heterotrophic production is transformed into organic detritus. The viral shunt, releasing on a global scale approximately 0.37-0.63 gigatonnes of carbon per year, is an essential source of labile organic detritus in the deep-sea ecosystems. This process sustains a high prokaryotic biomass and provides an important contribution to prokaryotic metabolism, allowing the system to cope with the severe organic resource limitation of deep-sea ecosystems. Our results indicate that viruses have an important role in global biogeochemical cycles, in deep-sea metabolism and the overall functioning of the largest ecosystem of our biosphere.

Prevalence of temperate viruses in deep South China Sea and western Pacific Ocean