The Global Centre for Risk and Innovation (GCRI)
Coral reefs, mangroves, seagrass meadows, kelp forests and open-ocean ecosystems support fisheries, protect coasts and store carbon. They are under pressure from warming, marine heatwaves, acidification, loss of oxygen, pollution and overfishing. This page sets out how these pressures act and combine, how ecosystem condition is observed, and what evidence serves the agencies and communities that protect and restore them.
GCRI · In development · service level R0
Marine ecosystems are the communities of ocean and coastal life, such as coral reefs, mangroves, seagrass, kelp forests and open-ocean food webs, together with their physical environment. Warming, marine heatwaves, acidification, deoxygenation, pollution and overfishing act on them together, and stressed systems recover more slowly.
Marine heat, sea surface temperature, chlorophyll and sea ice from satellite analyses, framed on Pacific Island states; each layer is a dated NASA product.
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Layers 1
Ocean state
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NASA GIBS / EOSDIS · ASTER GDEM (METI, NASA) · Natural Earth
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Marine heat, sea surface temperature, chlorophyll and sea ice from satellite analyses, framed on Pacific Island states.Satellite and model products as NASA publishes them, each with its own date; indicators, not assessments of any place; claim ceiling INTEGRATED.
Layers and dates
The working screen behind this subject: its structure, terms and states. Names are placeholders and values illustrative.
Marine ecosystems · Fishing grounds 3 · Season 1
| Small pelagic | 0.9 | 1.0 | Overfishing |
| Reef fish | 0.7 | 1.6 | Overfished |
| Tuna-like | 1.2 | 0.8 | Sustainable |
Habitats, trophic systems and ecosystem condition. The dossier below sets out how the risk develops, what is measured, where the data come from, how it is modelled and who decides.
Prolonged high sea temperatures cause coral bleaching, kelp loss and mass mortality of other species. Heatwaves are becoming more frequent and intense.
The ocean absorbs carbon dioxide, lowering pH and the carbonate available to corals, shellfish and plankton to build shells and skeletons.
Warmer water holds less oxygen and nutrient runoff fuels algal blooms that consume it. Low-oxygen zones expand and drive species away or kill them.
Reefs stressed by pollution and overfishing recover more slowly from bleaching. Loss of habitat-forming species cascades through the food web and the services ecosystems provide.
Each term as this page uses it. Where a standard-setting body defines the term, the wording follows that body.
| Term | Definition |
|---|---|
| Coral bleaching | Loss of the symbiotic algae from coral tissue, usually caused by prolonged heat stress. |
| Deoxygenation | The decline of oxygen in ocean waters due to warming and nutrient pollution. |
| Blue carbon | Carbon stored in coastal and marine ecosystems such as mangroves, salt marshes and seagrass. |
Each indicator carries its unit, its cadence, the kind of source behind it and the evidence label a value would carry. No values are shown: a programme supplies them under its own authority.
| Indicator | Unit | Cadence | Source type | Label |
|---|---|---|---|---|
| Degree heating weeks | degree Celsius weeks | daily | Satellite sea surface temperature products | OBSERVED |
| Live hard coral cover | percent of reef area | per survey | Reef monitoring surveys | OBSERVED |
| Mangrove extent | square kilometres | annual | Satellite mapping | OBSERVED |
| Surface ocean pH | pH units | per cruise or mooring | Ocean carbon observations | OBSERVED |
| Dissolved oxygen | micromoles per kilogram | per profile | Floats and ship observations | OBSERVED |
| Marine protected area coverage | percent of national waters | annual | World Database on Protected Areas | OFFICIAL |
| Species occurrence records | count by taxon and area | continuous | Biodiversity databases | REPORTED |
The topic as a computational graph: named sources feed the methods, an evidence review gates the outputs, and the decisions stay with the authorities that hold them.
Fig. 02Nodes carry their type, two metric rows and a state; connectors show what feeds what; dashed frames name the owners; the timeline is the cadence. Design of the pipeline, not a record of a run.
Named public datasets and institutional records, each with its licence class. Sources by agreement are used only under their terms and never republished.
| Source | What it gives | Licence class |
|---|---|---|
| NOAA Coral Reef Watch | Satellite sea surface temperature and bleaching heat stress products | Public domain, US government data |
| Allen Coral Atlas | Maps of shallow coral reef habitats and bleaching monitoring | Open, CC BY 4.0 |
| Global Mangrove Watch | Mangrove extent and change | Open, CC BY 4.0 |
| Ocean Biodiversity Information System (OBIS) | Marine species occurrence records | Open, CC0, CC BY or CC BY-NC per dataset |
| Protected Planet (World Database on Protected Areas) | Marine protected areas and OECMs | Free for non-commercial use, terms to check |
| Global Ocean Acidification Observing Network data | Ocean carbonate chemistry observations | Open, terms per data provider (to check) |
Oceans and Coasts prepares evidence. The decisions below are taken by the authorities named, under their own rules, and never by the platform.
| Who decides | The question | Evidence this page serves |
|---|---|---|
| Marine park and environment agencies | Where to protect, restore or reduce local pressures | Habitat maps; pressure overlays; heat stress |
| Fisheries authorities | Whether to adjust fishing in degraded habitats | Habitat condition and species evidence |
| National biodiversity planners | How to meet marine protection and restoration targets | Protected area coverage; habitat change |
Marine heatwaves cause coral bleaching, kelp loss and mass mortality of invertebrates; as they become more frequent, the time for recovery between events shortens. Ocean acidification, the fall in pH as seawater absorbs carbon dioxide, makes it harder for corals, shellfish and some plankton to build carbonate structures. Deoxygenation, from warming and from nutrient run-off, expands low-oxygen zones that exclude many species. Species ranges shift towards the poles and to deeper water, reorganizing communities.
These climate pressures act alongside overfishing, habitat destruction from trawling and coastal development, pollution and invasive species. Interactions are often non-additive: a reef weakened by pollution recovers more slowly from bleaching, and the loss of grazing fish can let algae overgrow corals. Food webs transmit change, through trophic cascades in which the removal of a predator or the collapse of a prey species reshapes the whole system.
Restoration science is advancing, with active coral gardening, mangrove replanting and seagrass recovery, but success depends on addressing the pressures that caused the loss and on choosing sites where conditions will remain suitable.
Diver and video surveys, eDNA and long-term monitoring sites give direct evidence but cover small areas.
Satellite and aerial imagery map shallow habitats and sea-surface temperature; depth and turbidity limit what can be seen.
Food-web and species-distribution models explore scenarios; they depend on assumptions about behaviour and adaptation.
Limits: baselines are often missing or already degraded, so condition is measured against a shifted reference. Deep-sea and open-ocean ecosystems remain sparsely observed.
The current service level is R0: information and enquiries. An enquiry receives a reference and names the next step; applications, payments, compute allocations and registrations open only when their team, terms and review capacity exist.