Deep dive: Marine & freshwater biodiversity

Why It Matters

Oceans cover 71 percent of the Earth's surface and generate over half of the planet's oxygen, yet only 8.3 percent of marine area falls within protected zones as of early 2026, far short of the 30 percent target set by the Kunming-Montreal Global Biodiversity Framework for 2030 (UNEP-WCMC, 2026). Freshwater ecosystems, which hold 10 percent of all known species despite covering less than 1 percent of the planet's surface, have experienced a staggering 83 percent decline in monitored vertebrate populations since 1970 (WWF Living Planet Report, 2024). These aquatic systems underpin global food security (3.3 billion people depend on aquatic foods for at least 20 percent of animal protein intake), regulate climate through carbon sequestration in mangroves, seagrass, and salt marshes, and support livelihoods for hundreds of millions of coastal and riparian communities. Yet overfishing, pollution, habitat destruction, climate-driven warming, ocean acidification, and emerging threats like deep-sea mining continue to degrade these ecosystems at an alarming pace. For sustainability professionals, understanding the policy landscape, restoration science, financing mechanisms, and governance gaps in marine and freshwater biodiversity is critical to driving meaningful action before irreversible tipping points are crossed.

Key Concepts

Marine protected areas (MPAs). MPAs are geographically defined ocean zones where human activity is restricted to conserve biodiversity and ecosystem services. The quality of protection matters as much as quantity: a 2025 analysis by the Marine Conservation Institute found that only 2.8 percent of the ocean is in fully or highly protected MPAs where extractive activities are prohibited. The remaining designated areas permit fishing, shipping, or mining, significantly reducing conservation effectiveness. The High Seas Treaty (BBNJ Agreement), adopted in June 2023, provides the first legal framework for establishing MPAs beyond national jurisdiction, but ratification and implementation remain slow.

Blue carbon ecosystems. Mangroves, seagrass meadows, and tidal salt marshes sequester carbon at rates two to four times higher per unit area than terrestrial forests (IPCC, 2024). These "blue carbon" ecosystems also serve as nursery habitats for commercial fish species, buffer coastlines from storms, and filter pollutants. Despite their value, the world has lost roughly 35 percent of its mangroves and over 30 percent of seagrass coverage since the 1980s. Blue carbon credit projects have attracted over $500 million in investment since 2020, though methodological challenges around permanence and additionality persist.

Freshwater rewilding. River restoration, dam removal, and floodplain reconnection are gaining momentum as strategies to recover freshwater biodiversity. The European Union's Nature Restoration Law, adopted in 2024, requires member states to restore at least 25,000 km of rivers to free-flowing status by 2030. In the United States, over 100 dams were removed in 2024 alone, the highest annual total on record (American Rivers, 2025). Rewilding efforts have demonstrated rapid species recovery: salmon populations in the Elwha River in Washington state increased tenfold within five years of dam removal.

Coral reef restoration. Coral reefs support approximately 25 percent of marine species and provide ecosystem services valued at $375 billion annually, including fisheries, coastal protection, and tourism (ICRI, 2025). Warming oceans have triggered four global mass bleaching events since 1998, with the most severe recorded in 2024 when 77 percent of monitored reefs experienced bleaching-level thermal stress (NOAA Coral Reef Watch, 2025). Restoration approaches range from coral gardening and fragment transplantation to heat-tolerant coral breeding and assisted gene flow, with total global investment in coral restoration exceeding $10 billion since 2015.

Deep-sea mining governance. The International Seabed Authority (ISA) has issued 31 exploration licenses covering over 1.5 million square kilometres of ocean floor. Commercial extraction of polymetallic nodules, cobalt-rich crusts, and seafloor massive sulfides could begin within the decade, despite major gaps in scientific understanding of deep-sea ecosystems. Over 30 countries and major companies, including BMW, Volvo, Google, and Samsung SDI, have called for a moratorium or precautionary pause on deep-sea mining until adequate environmental safeguards are in place (Deep Sea Conservation Coalition, 2025).

Ocean acidification. Surface ocean pH has declined by 0.1 units since pre-industrial times, representing a 26 percent increase in acidity. This trend threatens calcifying organisms, including corals, shellfish, and plankton, that form the foundation of marine food webs. The rate of acidification is accelerating: NOAA reported in 2025 that pH decline in the North Pacific is occurring 10 percent faster than model projections from 2020, raising concerns about cascading impacts on fisheries and marine ecosystems.

What's Working

MPA expansion and the 30x30 push. Despite the gap between current coverage and the 2030 target, significant progress is being made. The United States designated the Pacific Remote Islands National Marine Sanctuary, protecting 777,000 square miles. The EU designated 12.7 percent of its marine waters as strictly protected by 2025. The Maldives announced plans to protect 20 percent of its Exclusive Economic Zone. The High Seas Treaty provides the legal infrastructure for protecting open ocean, and as of February 2026, 112 nations have signed and 15 have ratified the agreement (UN DOALOS, 2026).

Coral restoration innovation. Mars Coral Reef Restoration Programme in Indonesia has restored over 50 hectares of degraded reef using patented "Reef Stars" hexagonal structures, achieving 70 percent live coral cover within three years. The Australian Institute of Marine Science (AIMS) developed heat-tolerant coral strains using selective breeding and is conducting large-scale field trials across the Great Barrier Reef. The Coral Research and Development Accelerator Platform (CORDAP), backed by G7 nations, has committed $250 million to scale breakthrough coral resilience technologies. These efforts show that active restoration can complement passive protection when supported by adequate funding and science.

Freshwater restoration delivers rapid returns. Dam removal in the United States has become a proven conservation tool. The removal of four dams on the Klamath River in California and Oregon (completed in 2024) represented the largest dam-removal project in U.S. history and has already shown early signs of salmon and steelhead recovery (American Rivers, 2025). In Europe, the Rewilding Europe initiative has supported river restoration across 10 landscapes, reconnecting over 4,500 km of river habitat. Freshwater species reintroduction programs, including beaver rewilding in the UK, have demonstrated measurable improvements in water quality, flood mitigation, and local biodiversity within two to three years.

Blue carbon markets are growing. Verra's Verified Carbon Standard issued over 15 million blue carbon credits between 2020 and 2025, with mangrove and seagrass restoration projects commanding premium prices of $25 to $40 per tonne (Verra, 2025). Apple invested $50 million in mangrove restoration in Colombia and India as part of its carbon-neutral commitment. The Blue Carbon Buyers Alliance, launched in 2024, now includes 35 corporate buyers committed to purchasing blue carbon credits worth $200 million over the next five years.

What's Not Working

Paper parks and enforcement gaps. A substantial share of existing MPAs lack effective management. The MPA Guide assessment by Sala et al. (2025) found that only 21 percent of MPAs have management plans that are being fully implemented. In many developing nations, MPAs exist on paper but lack patrol vessels, monitoring technology, or enforcement capacity. Illegal, unreported, and unregulated (IUU) fishing continues within nominally protected zones, undermining conservation outcomes.

Deep-sea mining governance vacuum. The ISA has failed to adopt a mining code despite a 2023 deadline triggered by Nauru's invocation of the two-year rule. This regulatory vacuum means that exploitation applications could be considered without comprehensive environmental standards. Scientific understanding of deep-sea ecosystems remains rudimentary: an estimated 90 percent of deep-sea species are undescribed. The potential for irreversible harm to slow-recovering ecosystems (polymetallic nodule fields take millions of years to form) makes precautionary governance essential, yet geopolitical and commercial pressures continue to push toward extraction.

Freshwater neglect. Despite being the most threatened ecosystem type on Earth, freshwater habitats receive a disproportionately small share of conservation funding. An analysis by The Nature Conservancy (2025) found that less than 6 percent of global conservation spending targets freshwater ecosystems. River pollution from agricultural runoff, industrial discharge, and plastic waste continues to intensify in South and Southeast Asia, sub-Saharan Africa, and Latin America. Groundwater depletion threatens wetland ecosystems worldwide, with 21 of the world's 37 largest aquifer systems in decline.

Coral bleaching outpaces restoration. While coral restoration technology has advanced significantly, the scale of bleaching driven by ocean warming far exceeds restoration capacity. Current global restoration efforts cover roughly 1,000 hectares annually, whereas bleaching affects hundreds of thousands of hectares in a single event. Without rapid emissions reductions to limit warming to 1.5°C, even heat-tolerant coral strains may not survive the thermal stress projected for mid-century. The mismatch between the pace of degradation and the pace of restoration remains the central challenge.

Fragmented freshwater governance. Rivers cross political boundaries, creating coordination challenges. The Mekong, Nile, and Ganges river basins all face competing demands from hydropower, agriculture, industry, and conservation across multiple sovereign states. Transboundary water governance mechanisms remain weak, with many basin commissions lacking enforcement authority or adequate data-sharing agreements.

Key Players

Established Leaders

• IUCN — Maintains the Red List of Threatened Species, including aquatic assessments, and sets global standards for MPA effectiveness.
• NOAA — Operates Coral Reef Watch, manages U.S. marine sanctuaries, and leads ocean acidification monitoring.
• Great Barrier Reef Marine Park Authority (GBRMPA) — Manages the world's largest coral reef system; pioneered zoning-based MPA management.
• Ramsar Convention Secretariat — Administers the international treaty for wetland conservation covering 2,500+ sites across 172 countries.

Emerging Startups

• Coral Vita — Grows heat-resilient coral in land-based farms using micro-fragmentation and assisted evolution; operates in the Bahamas and expanding globally.
• NatureMetrics — eDNA water sampling technology for freshwater and marine biodiversity monitoring; raised $25 million Series B in 2025.
• Urchinomics — Converts overabundant sea urchins (which destroy kelp forests) into aquaculture products, combining restoration with revenue.
• Global Fishing Watch — Open-source platform using satellite AIS data and machine learning to track fishing activity and detect IUU fishing in MPAs.

Key Investors/Funders

• Bloomberg Ocean Initiative — Funded by Bloomberg Philanthropies; supports ocean data, MPA enforcement, and sustainable fisheries.
• The Ocean Cleanup — Raised over $100 million; deploys technology to remove plastics from rivers and ocean gyres.
• Bezos Earth Fund — Committed $500 million to ocean conservation, including blue carbon, MPAs, and coral reef research.
• Global Fund for Coral Reefs (GFCR) — UN-backed blended finance vehicle mobilizing $625 million for coral reef conservation and sustainable livelihoods.

Sector-Specific KPI Benchmarks

Action Checklist

• Assess aquatic nature dependencies. Use the TNFD LEAP framework to identify how your organization depends on and impacts marine and freshwater ecosystems across supply chains.
• Support the 30x30 MPA target. Advocate for well-managed, fully protected MPAs rather than paper parks. Fund enforcement capacity where it is lacking.
• Invest in blue carbon. Evaluate mangrove and seagrass restoration credits as high-co-benefit offsets; verify projects meet Verra VCS or Plan Vivo standards with transparent monitoring.
• Eliminate supply-chain links to IUU fishing. Require suppliers to provide vessel tracking data and adopt Global Fishing Watch or equivalent transparency platforms.
• Engage on deep-sea mining governance. Support calls for a precautionary pause and participate in ISA stakeholder consultations to ensure robust environmental standards before any exploitation begins.
• Fund freshwater restoration. Prioritize investments in dam removal, river connectivity, and wetland rehabilitation. Freshwater ecosystems deliver outsized biodiversity returns per dollar invested.
• Adopt science-based targets for nature. Align corporate biodiversity commitments with the Science Based Targets Network (SBTN) freshwater and ocean guidance, setting measurable, time-bound goals.

FAQ

Why does the 30x30 target focus on "effective" protection? Designating an area as an MPA is necessary but not sufficient. Research by Sala et al. (2025) shows that fully protected marine reserves deliver five to ten times the biomass of exploited areas, while MPAs that permit extractive activities show minimal difference from unprotected zones. The emphasis on effectiveness ensures that the 30 percent target translates into genuine conservation outcomes rather than lines on a map. Quality of management, enforcement capacity, and community engagement determine whether protection works.

Can coral reefs survive if global warming exceeds 1.5°C? The IPCC projects that 70 to 90 percent of tropical coral reefs will be lost at 1.5°C of warming and over 99 percent at 2°C. Active restoration, heat-tolerant breeding, and assisted gene flow can improve resilience for individual reefs, but they cannot substitute for emissions reductions. The most promising strategy combines aggressive decarbonization with targeted restoration of reefs in thermal refugia, areas where local oceanographic conditions provide relative cooling. Even in a 1.5°C scenario, reef ecosystems will look fundamentally different from today, with shifts in species composition and reduced structural complexity.

What is the business case for freshwater biodiversity? Companies in food and beverage, agriculture, textiles, mining, and energy sectors depend on reliable freshwater supplies. The World Bank estimates that water scarcity could reduce GDP by up to 6 percent in some regions by 2050. Investing in watershed health through restoration, pollution reduction, and sustainable water management reduces operational risk, lowers water treatment costs, and secures social license to operate. Nestlé, AB InBev, and Unilever have each invested over $100 million in watershed restoration projects since 2020, reporting measurable improvements in water quality and supply reliability.

How does deep-sea mining threaten marine biodiversity? Polymetallic nodule mining involves vacuuming the seabed at depths of 4,000 to 6,000 meters, destroying slow-growing organisms and creating sediment plumes that can disperse hundreds of kilometres. A 2025 study in Nature Ecology & Evolution found that mined areas showed less than 5 percent recovery of fauna after 26 years. The metals targeted (manganese, nickel, cobalt, copper) are used in batteries and electronics, but terrestrial recycling, substitution, and reduced material intensity offer alternative supply pathways that avoid irreversible deep-sea harm.

How can companies verify marine and freshwater conservation claims? Look for projects verified under recognized standards (VCS, Plan Vivo, Blue Carbon Accounting Framework) with transparent monitoring data, independent third-party audits, and documented community consent processes. eDNA sampling, satellite imagery, and acoustic monitoring provide objective, repeatable evidence of biodiversity outcomes. Avoid projects that rely solely on modeled projections without field verification or that lack clear permanence commitments.

Sources

• UNEP-WCMC. (2026). Protected Planet Report 2026: Marine Protected Area Coverage and Effectiveness. United Nations Environment Programme World Conservation Monitoring Centre.
• WWF. (2024). Living Planet Report 2024: Freshwater Biodiversity Decline and Recovery Pathways. World Wildlife Fund.
• Marine Conservation Institute. (2025). Marine Protection Atlas: Fully and Highly Protected Ocean Areas. Marine Conservation Institute.
• NOAA Coral Reef Watch. (2025). Global Coral Bleaching Event 2024: Thermal Stress Analysis and Reef Impact Assessment. National Oceanic and Atmospheric Administration.
• ICRI. (2025). Status of Coral Reefs of the World: 2025 Update. International Coral Reef Initiative.
• American Rivers. (2025). Dam Removal in 2024: Record Year for River Restoration. American Rivers.
• Deep Sea Conservation Coalition. (2025). The Case for a Moratorium on Deep-Sea Mining: Corporate and Government Positions. DSCC.
• Verra. (2025). Blue Carbon Credit Issuance and Pricing Trends 2020-2025. Verra.
• Sala, E. et al. (2025). MPA Guide: Assessing Marine Protected Area Management Effectiveness Globally. Nature.
• The Nature Conservancy. (2025). Freshwater Conservation Funding Gap Analysis: Global Investment Trends and Priorities. TNC.
• IPCC. (2024). AR6 Synthesis Update: Ocean and Cryosphere in a Changing Climate. Intergovernmental Panel on Climate Change.
• UN DOALOS. (2026). Status of the BBNJ Agreement: Signatures and Ratifications. United Nations Division for Ocean Affairs and the Law of the Sea.