Sentinel Sites – Marine Institute Staging

We monitor dedicated coastal sites around Ireland to track environmental change and conditions affecting ocean health, marine life, and coastal communities.

How Sentinel Sites work

We collect continuous, high-frequency measurements at fixed locations along Ireland’s west coast. The sites track Essential Ocean Variables (EOVs), which are used worldwide to monitor ocean health.

a tidal lagoon at Lough Furnace, Co. Mayo
a sheltered bay at Lehanagh Pool, Co. Galway
an open coastal site at Mace Head, Co. Galway

Aquaculture cages and monitoring buoys in sheltered water at Lehanagh Pool, with a small workboat beside a large yellow instrument buoy and rocky hills onshore.

What we measure at our sites

Sensors and laboratory analysis monitor physical, chemical, and biological conditions across the sentinel-site network.

Core measurements

Continuous records cover temperature, salinity, dissolved oxygen, chlorophyll-a as a measure of phytoplankton, and pH as a measure of acidity.

Carbon and ocean chemistry

Selected sites measure pCO₂, or carbon dioxide in seawater, to track ocean acidification.

Water sampling and biological data

Monthly sampling covers phytoplankton and zooplankton, nutrients such as nitrate, phosphate, and silicate, and dissolved inorganic carbon and alkalinity. These samples validate sensor data and provide deeper insight into ecosystem changes.

Real-time data and monitoring

Mobile networks transmit sensor data automatically every two hours, making it available in near real time.

We store and manage the observations through our environmental data platform. All data goes through quality checks before final release to ensure accuracy and reliability.

Why this monitoring matters

Sentinel-site observations help us understand how Ireland’s coastal waters are changing and detect long-term trends such as warming seas and increasing ocean acidity.

climate-change monitoring and adaptation
fisheries and aquaculture planning
marine spatial planning
biodiversity protection
environmental management and policy

Tracking environmental change

Data collected at Mace Head since 2018 shows trends that are higher than wider North Atlantic averages. The findings highlight the importance of sustained coastal monitoring.

rising sea-surface temperature
increasing levels of carbon dioxide (pCO₂)

Two Mace Head time-series charts show strong seasonal variation and overall increases in surface-water carbon dioxide and temperature from September 2018 to 2025. Trend lines indicate carbon dioxide rose by about 5.2 mic

Sentinel site locations

Mace Head, Co. Galway: an open coastal site with strong ocean influence that supports detailed monitoring of ocean chemistry and climate change.
Lehanagh Pool, Co. Galway: a sheltered bay used for aquaculture research and understanding coastal ecosystem dynamics.
Lough Furnace, Co. Mayo: a stratified lagoon where low oxygen levels can occur, supporting research on estuarine processes and fish populations.

Three maps of western Ireland marking Sentinel sites: Mace Head, established June 2018 by the Chemistry Team; Lehanagh Pool, March 2024 by the Aquaculture Team; and Lough Furnace, September 2025 by the Fisheries Team.

Supporting research and collaboration

The Sentinel Sites programme supports national and European collaboration and receives funding through the European Maritime, Fisheries and Aquaculture Fund (EMFAF).

research institutions
government bodies
industry partners
international monitoring networks

Sentinel Sites monitoring in Irish waters