Category Archives: Ocean Chemistry and Ecosystems

In a new study published April 1 in Global Change Biology, NOAA oceanographers and colleagues have developed a new method to produce high-resolution projections of the range and onset of severe annual coral bleaching for reefs in the Gulf of Mexico and Caribbean. The scientists built on a previous study that used global climate models from the Fifth Assessment Report of the Intergovernmental Panel on Climate Change that produced projections at a very coarse resolution of about 70 miles or 100 kilometers. By using a regional oceanic model and an approach called statistical downscaling, the scientists calculated when increasingly warmer waters would cause severe bleaching on an annual basis. The resulting local-scale projections of bleaching conditions, at a resolution of about 6 miles or 10 kilometers, will help managers include climate change as a consideration in planning and conservation decisions.

Coral bleaching is a major threat to coral ecosystems and primarily occurs when ocean temperatures are warmer than has been normal in the past. Temperature stress disrupts the relationship between corals and the algae that live within their tissues; a relationship that usually benefits both parties. The algae are expelled as they cannot photosynthesize under the extreme conditions. The white limestone coral skeleton becomes visible through tissue that is now transparent since the expelled algae give corals their vibrant colors. Extensive coral bleaching events, called ‘mass bleaching’, have increased in frequency and severity over the past two decades and have contributed to overall reef loss globally.

The loss of coral reefs results in significant ecological, social and economic loss. Coral reefs provide rich habitat for valuable fisheries that people depend on for food. They also serve as protective buffers to coastlines by absorbing wave energy from storms, and they boost local economies by attracting tourists who fish, dive and explore these underwater treasures.

A main conclusion of the study is that almost all coral reef locations in the Gulf of Mexico and Caribbean are projected to experience bleaching conditions every yearby mid-century. This result applies to the past coarse-resolution projections as well as the new high-resolution projections. However, the high-resolution projections show there is great within-country variation in the projected timing of extreme conditions. There are locations within many countries where some reefs are projected to experience annual bleaching conditions 15 or more years later than other locations. This applies to reefs in Florida, the Bahamas, Cuba, Puerto Rico, the Dominican Republic, Turks and Caicos, and Mexico. Reefs projected to experience bleaching conditions later are conservation priorities. These locations are a type of refuge, and are among the locations most likely to persist as the climate changes.

NOAA’s Reef Manager’s Guide, which provides information on the causes and consequences of coral bleaching, outlines some of the management strategies and tools that can help reef managers address the coral bleaching threat. Find out more here.This study was funded by NOAA’s Coral Reef Conservation Program and supported by NOAA AOML. The Open Access paper can be downloaded by clicking the thumbnail to the left.

Originally published April 1st, 2015 by Edward Pritchard

New NOAA study finds natural climate cycles and

human activities are drivers of change

Scientists in the Gulf of Mexico now have a better understanding of how naturally-occurring climate cycles–as well as human activities–can trigger widespread ecosystem changes that ripple through the Gulf food web and the communities dependent on it, thanks to a new study published Saturday in the journal Global Change Biology.

A team of NOAA oceanographers spent three years reviewing over 100 indicators derived from environmental, fishery, and economic data, including sea surface temperature, currents, atmospheric patterns, fishing effort, harvest, and revenues. Through extensive analysis, they found a major ecosystem reorganization that appeared to be timed with a naturally-occurring climate shift that occurred around 1995.

The climate phenomenon is known as the Atlantic Multidecadal Oscillation (AMO), a climate signal in the North Atlantic Ocean that switches between cool and warm phases, each lasting for 20-40 years at a time. The AMO, which was in a cool phase between 1965 until 1995 and has been in a warm phase since, influences global ocean and weather conditions in the northern hemisphere such as hurricane activity in the Atlantic ocean and the severity and frequency of droughts.

However, the AMO is not as extensively studied as other climate phenomena, such as El Nino, and this study is the first to investigate what scientists hope will be many future studies examining how the AMO influences ecosystem-scale change in the Gulf. Scientists hope this work will spur interest in further studying this phenomenon and its implications for the marine environment in this region.

“These major ecosystem shifts have probably gone unrecognized to date because they are not apparent when considering single species or individual components of the ecosystem,” said lead investigator Dr. Mandy Karnauskas of NOAA’s Southeast Fisheries Science Center. “Only when we put a lot of things together — including currents, hypoxia, fish abundances, fishing effort, and more — does a strong climate signal emerge.”

Additionally, scientists observed shifts in many species around the late 1970s coincident with the advent of the U.S. Magnuson-Stevens Fishery Conservation and Management Act– a policy designed to set rules for international fishing in U.S. waters, make the expansion of certain fisheries more favorable for economic development, and ensure the long-term sustainability of the nation’s fish stocks.

Other human influences that are not as pronounced–or easily distinguishable–include coastal development, agricultural runoff, oil spills, and fishing. Natural phenomena like coastal storms and hurricanes play a role as well.

The scientists expect their study to be useful to resource managers throughout the Gulf region. While managers cannot control Earth’s natural climate cycles, they may need to consider how to alter management strategies in light of them, in order to effectively meet their mandates.

Karnauskas’ team included other scientists from NOAA Fisheries as well as NOAA’s Atlantic Oceanographic and Meteorological Laboratory, the University of Miami, and the University of Texas.

Click on the thumbnail to the left to download the full study.

Originally Published in March 2015 by Shannon Jones

NOAA has selected South Florida’s Biscayne Bay as one of the next Habitat Focus Areas under NOAA’s Habitat Blueprint. Habitat Blueprint offers opportunities for NOAA to partner with organizations to address coastal and marine habitat loss and degradation issues. It provides a framework, which builds upon existing programs, prioritizes activities, and helps users act strategically and preventively in order to sustain resilient and thriving marine and coastal ecosystems and resources.

OML is located on Virginia Key in south Florida, surrounded by the clear waters of Biscayne Bay. The bay provides a home for endangered species, seagrass nurseries, and feeding grounds for many valued fish. The bay’s clear waters also support regional economy, recreation, and tourism. In the past 20 years, scientists at AOML, Florida International University, Miami-Dade County Department of Environmental Resources Management, and South Florida Water Management District have observed a trend in increased concentrations of chlorophyll a, an index of phytoplankton abundance. Phytoplankton, also known as microalgae, are microscopic plants in the water column, requiring sunlight and nutrients to live. With increasing phytoplankton comes the potential for frequent algal blooms that damage seagrass beds by reducing the light available to seagrass.

The recorded increase in phytoplankton, coupled with the recent appearance of an expansive diatom bloom in the southern bay in 2013 and macroalgae overgrowing seagrass beds in the central bay is causing scientists to worry about the future of Biscayne Bay’s ecosystem. If phytoplankton continues to increase, the quality of Biscayne Bay’s clear, pristine water could decrease and seagrass could be be smothered causing a widespread loss that would be hard to halt or reverse.

AOML’s Chris Kelble is co-leading the implementation team with NOAA Southeast Fisheries Science Center’s Joan Browder in hopes of identifying solutions to improve Biscayne Bay health, before it declines. With the help of NOAA’s Habitat Blueprint, partnering organizations can develop assessments, experiments and analyses to ultimately protect, restore, and sustain Biscayne Bay’s healthy ecosystem.

Habitat Blueprint is providing grant opportunities for restoration projects in NOAA’s new Habitat focus areas. Up to $1.2 million is expected to be available to support comprehensive and cooperative habitat conservations projects in areas including Biscayne Bay, FL. Habitat Blueprints goal is to have projects that sustain resilient and thriving marine and coastal resources, communities, and economies. Interested parties must apply and submit proposals that address the unique, site-specific objectives and issues/concerns that have been identified for Biscayne Bay, in hopes of restoring degraded areas, protecting environmental habitats, and fostering resilient coastal communities.

Originally Published in January 2015 by Shannon Jones

A study of Galápagos’ coral reefs provides evidence that reefs exposed to lower pH and higher nutrient levels may be the most affected and least resilient to changes in climate and ocean chemistry.

The Galápagos Islands are a unique habitat that allows scientists to study many ecological conditions, including exposure to naturally high levels of oceanic carbon dioxide. The coasts of the Galápagos are bathed in upwelled water from the deep ocean. This upwelled water has high carbon dioxide concentrations. Greater levels of carbon dioxide result in lower pH levels in seawater, making it more acidic.  Waters with high carbon dioxide can have negative affects on some organisms, like corals, that build their skeletons underwater. These naturally high levels of carbon dioxide surrounding the Galápagos are a present day example of the conditions expected throughout the rest of the tropics by the 2050’s.

Warm water temperatures are another factor affecting the Galápagos. The 1982-1983 El Niño Southern Oscillation warming event increased water temperatures in the Galápagos 3-4 degrees C above the usual maximum sea temperatures.  This warming physically stressed Galápagos corals, causing them to expel the algae living in their tissues and become completely white or bleached. This and other similar coral bleaching events coupled with the naturally occurring high levels of carbon dioxide, made it difficult for coral reefs to rebuild their calcium carbonate skeletons.  None of the Galápagos’ southern reefs show signs of revival and the only reef recovering is off the far northern island, Darwin.

As a coral ecologist and lead researcher for NOAA’s National Coral Reef Monitoring Program, Derek Manzello gathered an abundance of data on the seawater surrounding the southern Galápagos Islands, but he had limited information on the seawater in the northern islands. Thanks to the Khaled bin Sultan Living Ocean’s Foundation, Manzello and his team were able to venture to Darwin and conduct field studies comparing corals and seawater chemistry between the southern and northern islands. They discovered that at the present day acidification levels, corals can recover from severely stressful events, but their recovery is dependent on water quality conditions.

In the Galápagos study, waters have lower pH and higher nutrients in the southern Islands.  The team measured changes in coral density to compare growth rates of corals in the southern and northern waters. Corals, like trees, have an annual banding pattern, which is used to determine annual growth rates. Manzello’s team took core samples from corals, and examined their density bands with a micro-CT scanner, producing three-dimensional X-ray images.  Using these images, scientists observed healthier annual growth rates and density patterns for corals in the northern waters.  Corals in the southern waters, which were exposed to elevated nutrients and high CO2 levels due to upwelling, showed less skeletal growth.

“The Galápagos reefs provide one piece of the science of predicting how coral reefs will fare with continued warming and ocean acidification.” Says Manzello “There are other areas with high levels of carbon dioxide that do not experience as high of nutrient values as the Galápagos. This allows us to understand how acidification may impact the future of coral reefs through the worlds oceans.”

With support from NOAA’s Coral Reef Conservation and Ocean Acidification Programs, NOAA oceanographers can continuously evaluate, monitor, and study the effects of ocean acidification. Learn more about AOML’s collaborative ocean acidification efforts in the Island of Maug and the Florida Keys.

Originally Published in January 2015 by Shannon Jones

The latest episode of the educational television series “Waterways” features coral research conducted by NOAA scientists in the Florida Keys. As the global ocean becomes more acidic, NOAA is documenting these changes and their impact on organisms like corals. The first part of the episode entitled “Ocean Acidification & Tortugas Tide Gauge”   features AOML researchers discussing how they study this process and the high tech tools they use to monitor and describe changes in coral growth due to a more acidic ocean.

The ocean is becoming more acidic, but what does that really mean? On a pH scale of 1 – 14, 1.0 is strongly acidic and 14.0 is strongly alkaline or basic; typically ocean waters are slightly alkaline and fall around 8.0-8.1 on this scale. Over the past hundred years, the pH of seawater has decreased, dropping 0.1 pH units. This is due to ocean acidification, a process that occurs when seawater absorbs carbon dioxide (CO2) from the air. The amount of carbon dioxide in the atmosphere has steadily increased since the late 1800s. As more carbon dioxide is added to the air, the amount absorbed into the oceans increases, further decreasing pH. NOAA scientists monitor these changes and their possible effects.

Some of the organisms affected by ocean acidification are corals and shellfish, animals that build their skeletons or exoskeletons underwater. Stony corals secrete skeletons made of calcium carbonate, or limestone, and build coral reefs. These reef ecosystems are valuable resources to many organisms, which rely on the corals for shelter and food.  As the corals build their skeletons, organisms, such as fish and sponges, simultaneously eat away at the calcium carbonate.  This back and forth process of growth and erosion is a natural phenomenon in the coral reef ecosystem.

As seawater’s pH decreases, it becomes more difficult for corals to efficiently produce limestone. The trend of ocean acidification may result in coral reefs eroding faster than they are being built.  Scientists must measure the net growth, how fast a coral is growing, subtracted by how fast it is eroding, in order to determine the negative impacts of ocean acidification on corals. Using this formula, NOAA scientists discovered coral reefs in the Florida Keys are in an erosive state, losing grams of calcium carbonate per year.  One third of reefs in the wider Caribbean are eroding faster than they are growing, which could be detrimental to ocean and reef health. Twenty five percent of ocean animals rely on coral reefs to survive and many reef-associated organisms are important sources of protein for human populations along tropical coastlines.

With support from NOAA’s Coral Reef Conservation and Ocean AcidificationPrograms, AOML scientists established a long-term monitoring site to learn more about the effects of ocean acidification. At Cheeca Rocks, in the Florida Keys National Marine Sanctuary, there is a Moored Autonomous pCO2 (MAPCO2) buoy constantly collecting data on carbon dioxide in the air and water, seawater pH, and temperature, providing NOAA scientists the opportunity to observe changes in the environment.  These data are reported in near-real-time on the internet via satellite relay.

The bands on this piece of coral  represent a decade worth of  coral growth.  Credit: NOAA/AOML

Scientists can measure changes in a coral’s growth and density to determine how it is affected by acidification. Corals, like trees, have an annual banding pattern, which is used to determine annual growth rates. Scientific divers take core samples from larger corals, and examine their density bands with a micro-CT scanner. The scanner produces three-dimensional X-ray images that allow scientists to study the how much skeletons grow each year. A different three-dimensional scanner accurately measures the surface area and volume of living corals, whose architecturally complex exterior make it very challenging to measure.

With these long term monitoring sites and innovative technologies, scientists can provide information and analysis that helps resource managers and political leaders make laws and decisions for the future. This research may help discover methods to reduce the impacts from ocean acidification and mitigate the current damage to coral reefs.

With almost 300 episodes produced since 1993, the “Waterways” series is a joint project between Everglades National Park, Florida Keys National Marine Sanctuary, and the U.S. Environmental Protection Agency. Waterways inform viewers of the diverse wonders of the south Florida ecosystem, and the research and conservation programs that protect them. “Waterways” airs on public and government channels throughout the state of Florida — check local listings for scheduling. Episodes can be viewed on the WaterwaysTvShow YouTube channel.

The NOAA Coral Reef Conservation Program supports effective management and sound science to preserve, sustain and restore valuable coral reef ecosystems for future generations. The program works in strong partnership with coral reef managers to protect coral reefs by addressing national threats, including impacts from fishing, pollution and climate change, and implementing local conservation activities.

The Ocean Acidification Program (OAP) provides leadership to understand and predict changes in the Earth’s environment as a consequence of continued acidification of the oceans and Great Lakes, and conserve and manage marine organisms and ecosystems in response to such changes.  In order to do this the OAP fosters and maintains relationships with scientists, resource managers, stakeholders, policy makers, and the public in order to effectively research and monitor the effects of changing ocean chemistry on economically and ecologically important ecosystems and species.