Open Data Sources for Marine Conservation: A Practical Guide

Field surveys capture what is happening at your site right now. But marine ecosystems are shaped by forces that operate across larger scales: ocean temperature, currents, nutrient inputs, historical species distributions, and land-use changes on shore. Open data sources fill these gaps by providing environmental context, historical baselines, and biodiversity records that complement your field measurements.

This guide covers the most important open data sources for marine conservation, explains what each one provides, and shows how to combine them for site-level analysis.

Why open data matters for marine conservation

Open data transforms marine monitoring from site-level snapshots into contextual analysis:

• Temperature anomalies from satellite data explain sudden coral bleaching events that field surveys alone cannot predict.
• Historical species occurrence records from OBIS reveal whether a species was present before your monitoring began.
• Land cover data shows whether coastal development or deforestation is increasing sediment and nutrient runoff to your marine site.
• Global population data quantifies human pressure on coastal ecosystems.
• Standardized taxonomy from WoRMS ensures that your species records are comparable with global databases.

Without this context, field data tells you what is happening but not why.

CMEMS: Copernicus Marine Environment Monitoring Service

What it provides

CMEMS is the European Union's operational marine data service. It delivers gridded ocean data products derived from satellite observations and numerical models.

Key variables

• Sea surface temperature (SST): daily and monthly, global coverage at approximately 5 km resolution.
• Sea surface salinity: important for estuarine and coastal sites.
• Chlorophyll-a concentration: proxy for phytoplankton productivity and nutrient enrichment.
• Ocean currents: surface and subsurface current speed and direction.
• Wave height and period: relevant for exposed reef and seagrass sites.
• Dissolved oxygen: available from model reanalysis products.

Use cases

• Overlaying SST time series on coral bleaching monitoring data.
• Detecting nutrient plumes from elevated chlorophyll-a near coastal sites.
• Understanding current patterns that affect larval dispersal and sediment transport.

Access

CMEMS data is accessible through the Copernicus Marine Data Store. Registration is required (no cost). Data can be downloaded in NetCDF format or accessed through APIs.

MariMap auto-integrates CMEMS SST and chlorophyll-a data on the site environment dashboard.

NOAA Coral Reef Watch

What it provides

NOAA Coral Reef Watch is the primary global system for monitoring thermal stress on coral reefs. It translates satellite SST data into reef-specific stress metrics.

Key products

• SST Anomaly: difference between current temperature and the long-term monthly average.
• HotSpot: current SST minus the maximum monthly mean (the bleaching threshold).
• Degree Heating Weeks (DHW): cumulative thermal stress over the past 12 weeks. DHW above 4 indicates likely bleaching; above 8 indicates severe bleaching and mortality risk.
• Bleaching Alert Level: a 5-level alert system from No Stress to Alert Level 2.
• 7-day and seasonal outlooks: forecast models that predict thermal stress weeks to months ahead.

Use cases

• Setting alert triggers for emergency monitoring during bleaching events.
• Contextualizing coral mortality observed during field surveys.
• Planning survey timing around predicted stress periods.
• Reporting bleaching risk exposure in site condition reports.

Access

Products are available through the NOAA Coral Reef Watch website and data portal. Near-real-time data is updated daily. Data resolution is 5 km (global) and 1 km (regional products).

MariMap auto-integrates Coral Reef Watch alerts and DHW data at the site level.

Sentinel-2 / CDSE: Satellite imagery for habitat mapping

What it provides

Sentinel-2 is a European Space Agency satellite mission that captures multispectral imagery at 10 m resolution with a 5-day revisit cycle. The Copernicus Data Space Ecosystem (CDSE) provides access to the imagery.

Key applications

• Shallow water habitat mapping: identifying coral reef, seagrass, and sand zones from spectral signatures.
• Turbidity and sediment plume detection: visible-band imagery shows sediment inputs from rivers and runoff.
• Mangrove extent monitoring: vegetation indices (NDVI) track mangrove canopy changes.
• Coastal development monitoring: detecting new construction, dredging, or land reclamation near marine sites.

Use cases

• Creating habitat maps for site-level management plans.
• Detecting changes in seagrass extent between field surveys.
• Documenting sediment plumes after storms or construction events.
• Monitoring mangrove canopy health and deforestation.

Access

Sentinel-2 imagery is available through CDSE (free registration required). Imagery can be viewed online, downloaded as GeoTIFF, or processed through cloud platforms.

Google Earth Engine

What it provides

Google Earth Engine (GEE) is a cloud computing platform that provides access to a multi-petabyte catalog of satellite imagery and geospatial datasets, along with processing tools for analysis.

Key applications

• Historical time series analysis: access decades of Landsat and Sentinel data to analyze long-term change.
• Composite imagery: create cloud-free mosaics from multiple satellite passes.
• Custom indices: calculate vegetation indices, water quality indices, or habitat classification at scale.
• Change detection: compare images from different time periods to quantify habitat loss or gain.

Use cases

• Analyzing 30 years of coastline change using Landsat archive data.
• Creating annual seagrass extent maps from Sentinel-2 composites.
• Quantifying mangrove loss over the past decade for baseline assessments.

Access

GEE requires a Google account and project registration. Academic and non-profit access is available at no cost. Analysis runs in the cloud using JavaScript or Python APIs.

GHSL: Global Human Settlement Layer

What it provides

The Global Human Settlement Layer maps built-up areas, population density, and settlement patterns globally using satellite imagery and census data.

Key variables

• Built-up surface: the physical footprint of buildings and infrastructure.
• Population grid: estimated population count per grid cell.
• Degree of urbanization: classification of settlements from rural to urban.

Use cases

• Quantifying human pressure on coastal sites by measuring nearby population density.
• Identifying growing settlements that may increase runoff, waste, or fishing pressure.
• Supporting stakeholder analyses for marine protected area management plans.

Access

GHSL data is available from the European Commission Joint Research Centre. Downloads are available in GeoTIFF format at multiple resolutions.

CLMS: Copernicus Land Monitoring Service

What it provides

The Copernicus Land Monitoring Service provides land cover, vegetation, and water body data for Europe and globally.

Key products

• Global land cover maps: annual land cover classification at 100 m resolution.
• Vegetation indices: NDVI and leaf area index for monitoring vegetation health.
• Water bodies: extent and seasonal variation of freshwater bodies.

Use cases

• Monitoring land use change in coastal watersheds that affect marine water quality.
• Tracking deforestation in upstream catchments that increases sediment delivery to reefs.
• Assessing agricultural expansion near coastal sites.

Access

Available through the Copernicus Land Monitoring Service portal. Data downloads are in GeoTIFF and NetCDF formats.

WoRMS: World Register of Marine Species

What it provides

WoRMS is the authoritative global database of marine species names and taxonomy. It maintains the accepted scientific name, synonyms, and classification hierarchy for every known marine species.

Key features

• Name resolution: look up a species name to find the current accepted name and any synonyms.
• Taxonomic hierarchy: family, order, class, phylum classification for every species.
• AphiaID: a unique numeric identifier for each taxon, enabling precise cross-referencing between databases.

Use cases

• Validating species identifications from field surveys against the current accepted taxonomy.
• Resolving name changes when comparing historical and current species records.
• Standardizing species lists across multi-team monitoring programs.

Access

WoRMS is freely accessible through the web interface and REST API. Batch name matching is available for large species lists.

MariMap uses WoRMS as the taxonomic backbone for species lists.

OBIS: Ocean Biodiversity Information System

What it provides

OBIS is the global open-access repository for marine species occurrence records. It aggregates data from thousands of institutions, surveys, and monitoring programs worldwide.

Key features

• Species occurrence records: where and when a species was observed, with coordinates and dates.
• Spatial search: query by geographic area to find all recorded species at or near your site.
• Temporal range: records spanning decades, enabling historical baseline analysis.
• Standardized format: all records are in Darwin Core format with taxonomy validated against WoRMS.

Use cases

• Establishing a species baseline for a new monitoring site using historical records.
• Comparing your survey species list against all known occurrences in the area.
• Identifying species that have been recorded historically but not observed in recent surveys (potential local extinctions).

Access

OBIS is accessible through the web portal and API. Data downloads are in CSV and Darwin Core Archive formats.

IUCN Red List

What it provides

The IUCN Red List of Threatened Species assesses the conservation status of every evaluated species globally, using standardized criteria for extinction risk.

Key categories

• Critically Endangered (CR): extremely high risk of extinction.
• Endangered (EN): very high risk of extinction.
• Vulnerable (VU): high risk of extinction.
• Near Threatened (NT): close to qualifying for a threatened category.
• Least Concern (LC): low risk.
• Data Deficient (DD): not enough information to assess.

Use cases

• Flagging threatened species detected in your surveys for prioritized reporting.
• Supporting biodiversity credit assessments that weight outcomes by species conservation status.
• Meeting TNFD and CSRD disclosure requirements for threatened species presence at operational sites.

Access

The IUCN Red List API provides programmatic access to species assessments. Web search is available on the IUCN Red List website.

MariMap auto-enriches species records with IUCN conservation status.

H3: Hexagonal spatial indexing

What it provides

H3 is Uber's open-source hexagonal hierarchical spatial indexing system. It divides the earth's surface into hexagonal grid cells at multiple resolutions.

Key features

• Consistent cell shapes: hexagons tile without distortion, unlike rectangular grids.
• Hierarchical resolution: from continental scale (resolution 0) to sub-meter precision (resolution 15).
• Efficient spatial queries: fast neighbor lookups, containment tests, and aggregation.

Use cases

• Aggregating survey data from multiple sites into regional summaries.
• Creating heat maps of monitoring coverage or species richness.
• Spatial analysis of environmental gradients across your monitoring network.

MariMap uses H3 for spatial indexing and regional analysis features.

Combining multiple data sources for site-level analysis

The real power of open data emerges when you combine sources:

1. Start with field survey data as the primary layer (benthic cover, fish abundance, seagrass density).
2. Add environmental context from CMEMS (SST, chlorophyll-a) and Coral Reef Watch (DHW, bleaching alerts).
3. Overlay satellite imagery from Sentinel-2 for habitat extent and change detection.
4. Enrich species records with WoRMS taxonomy, OBIS historical occurrences, and IUCN conservation status.
5. Assess human pressure with GHSL population data and CLMS land cover change.
6. Index spatially with H3 for regional comparisons and aggregation.

MariMap auto-integrates many of these sources at the site level, presenting them alongside field data on the environment dashboard and in analytics views. See the environmental data and data sources pages for details.

Licensing considerations

Most of the data sources listed here are open access, but licensing terms vary:

• CMEMS and Copernicus products: Copernicus license, free for all uses with attribution.
• NOAA Coral Reef Watch: US government work, public domain.
• Sentinel-2: Copernicus license, free with attribution.
• Google Earth Engine: Free for research and non-commercial use; commercial use requires a paid plan.
• GHSL: European Commission license, free with attribution.
• WoRMS: Creative Commons BY 4.0, free with attribution.
• OBIS: Data use depends on individual dataset licenses; most are CC-BY or CC-0.
• IUCN Red List: Terms of use apply; citation required.

Always check the specific license terms before publishing derived products or including data in commercial reports.

MRV readiness and disclosure alignment

• Baseline vs repeat surveys: mark baselines and keep repeat surveys on comparable geometry.
• Monitoring plan logic: define cadence, QA/QC thresholds, and conservative handling of uncertainty.
• Outcome types and claims discipline: record uplift, avoided loss, or maintenance credits; separate inputs from verified outcomes.
• Rights and integrity: document FPIC, customary marine tenure, OECM, ICCA, benefit sharing, durability mechanisms, and leakage risk.
• Disclosure alignment: map indicators to TNFD, CSRD, ESRS, EU Taxonomy, SBTN, and SBTi requirements.
• Use the Metrics Reference and Data Providers for definitions and sources.

Related guides

• Understanding Satellite and Environmental Data
• Data Export Formats in MariMap
• Coral Reef Monitoring in MariMap
• Seagrass Monitoring in MariMap

References

• Copernicus Marine Service
• NOAA Coral Reef Watch
• Sentinel-2 / CDSE
• GBIF
• OBIS
• WoRMS
• IUCN Red List