Monitoring ocean acidification in Caribbean coral reefs

An ocean acidification buoy in Puerto Rico helps scientists understand changing conditions in our oceans and atmosphere.

Yellow buoy in the blue ocean off the coast of Puerto Rico, land can be seen in the background
The La Parguera NOAA Ocean Acidification program buoy is moored in a coral reef location on the southwest side of Puerto Rico monitoring CO2, salinity, chlorophyll, oxygen, and pH in the water and air.

Since 2008, a NOAA Ocean Acidification Program (OAP) buoy has been positioned in La Parguera, Puerto Rico where it collects data for scientists studying the chemistry, biology, geology, and physics of the Caribbean Sea. A recent NOAA video available in English and in Spanish explains the impact of increased levels of carbon dioxide (CO2) and ocean acidification on ocean chemistry and on marine life in our oceans. 

Knowledge of ocean acidification and warming conditions is critical to advance the 2030 Sustainable Development Goals of the United Nations in Puerto Rico. The information provided by NOAA is relevant for tracking progress towards achieving mitigation and adaptation actions around the island because rapid changes in ocean acidification and warming have significant impacts on the ocean’s ability to sequester CO2 from the atmosphere and ocean ecosystem services (e.g., tourism, food, coastal protection).

What is Ocean Acidification? 

Recent measurements indicate that atmospheric CO2 levels have increased by 50% due to human activities such as the burning of fossil fuels. The ocean absorbs about a third of the COthat is released to the atmosphere.  As atmospheric CO2 has increased, so has the amount of COabsorbed by the ocean. More CO2in the water increases our ocean’s acidity, a phenomenon known as ocean acidification

When COenters the ocean, it dissolves in the salt water creating other compounds such as carbonic acid, bicarbonate, and carbonate ions. Shellfish and corals rely on carbonate ions in the water to build their skeletons and shells. Higher levels of CO2 in the water column causes less carbonate ions in the ocean, and as a result, shellfish and corals have thinner shells, slower growth rates, and rising death rates. 

A Decade of Ocean Acidification Observations in Puerto Rico 

Ten years ago, there were no studies of carbonate chemistry and no ocean acidification observations in Puerto Rico. Ocean acidification studies began with the installation of a buoy in a coral reef location on the southwest of the island in 2008 as part of the then Atlantic Ocean Acidification Test-Bed. The buoy is part of a global effort by NOAA to monitor ocean acidification. There are currently 19 NOAA OAP buoys in coastal, open ocean, and coral reef ecosystems around the world. The La Parguera buoy is the only one located in the Caribbean monitoring coral reefs. The station is an important node contributing to the National Ocean Acidification Observing Network, a joint effort by NOAA OAP, the Pacific Marine Environmental Laboratory, the Caribbean Ocean Observing System (CariCOOS), and the University of Puerto Rico–Mayagüez. Today, the site is a fixed Climate Monitoring Station and contributes a suite of ecological measurements, such as calcification and bio-erosion. The buoy serves as a nexus for federal and academic monitoring and research, allows for testing of new technology and methods to improve the understanding of coastal carbonate chemistry, and raises community awareness and engagement.

OAP buoys are moored, allowing them to remain stationary so scientists can get measurements from the same place over time. Scientists then collect the data from the various buoys to better understand the geographic and temporal changes. The past decade of buoy data is key to understanding long-term acidification trends and more generally how ocean chemistry is changing over time. 

The buoy monitors several key indicators including 

● COin the water, 

● COin the air, 

● Salinity, 

● Chlorophyll content in the water, 

● Oxygen in the water, 

● and pH 

These observations have opened doors for other collaborations throughout the Caribbean including with NOAA’s Coral Reef Conservation Program, SeaGrant Puerto Rico, the University of New Hampshire, and the University of Puerto Rico. 

As work continues, the program is identifying and engaging stakeholders and partners, assessing needs, and generating products and tools that support management decisions, adaptation, and resilience in response to acidification. The NOAA OAP recently provided funds for a first-ever workshop in the region to begin planning for the development of a regional vulnerability assessment. This project will help provide the framework needed to evaluate ocean acidification vulnerabilities and engage local stakeholders, such as those working on coral restoration and coastal managers, in discussions of ocean acidification. There is currently little information about how ocean acidification impacts ecologically and economically important species and ecosystems in Puerto Rico. The buoy observations not only advance the science behind this global problem, but it also develops capacity building and empowers local communities with the tools to fight back against the effects of this global problem.

Ocean Acidification and Protected Resources 

While shell builders like shellfish and corals are directly affected by ocean acidification, other species are indirectly affected because they eat the shelled organisms or live in the habitats they create. Marine ecosystems have complex food webs, and impacts of ocean acidification will change the ocean from the smallest sea snail to the biggest whale. 

Office of Protected Resources, NOAA, 26 July 2021. Full article.

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