Tag: Oceans

Ocean in Peril: Understanding the Escalating Threat of Marine Heatwaves and Acidification

/ activist360


Ocean sea life and coral reef. Credit: Francesco Ungaro, Unsplash.


As the planet grapples with climate change, our oceans are experiencing unprecedented shifts. Recent research by Joel Wong, Matthias Münnich, and Nicolas Gruber, Column‐Compound Extremes in the Global Ocean published in the Journal of Oceanic Studies into the increasing frequency, intensity, and spatial extent of compound marine extremes—particularly marine heatwaves combined with ocean acidification—highlights a looming crisis for global marine ecosystems. The study, conducted over nearly six decades, offers important insights into these phenomena and underscores the urgent need for global environmental strategies.

The Escalating Intensity of Marine Extremes

The study analyzes data from 1961 to 2020, revealing a concerning trend in the behavior of oceanic compound extremes, referred to as Column-Compound Extreme Events (CCX). These events, characterized by simultaneous occurrences of extreme heat and acidity, have become more intense and longer-lasting over the years. Such changes are primarily driven by global warming and increased carbon dioxide emissions, which not only warm but also acidify ocean waters at alarming rates.

Impact on Marine Life

The effects of these compound extremes are profound. Marine ecosystems, particularly coral reefs, kelp forests, and the myriad species dependent on them, face severe threats from prolonged exposure to extreme conditions. The study estimates that the habitable space within the water column has potentially reduced by up to 75%, a stark indication of the dire conditions many marine organisms now endure. This habitat compression threatens biodiversity, disrupts fishing industries, and jeopardizes the livelihoods of communities dependent on these ecosystems.

Geographic and Vertical Spread

The research identifies that these extremes are not uniformly distributed. Tropical and high latitude regions, known for their rich biodiversity, are the most affected. The impacts extend beyond the surface, complicating the survival conditions for species that cannot migrate to more hospitable waters.

Role of Climate Phenomena

El Niño and other climate phenomena play a significant role in modulating these compound events. The study highlights specific patterns and regional variations in CCX occurrences, linking them to broader climatic shifts that influence ocean currents and temperature distribution.

Need for Advanced Modeling Techniques

A key contribution of this research is the development of advanced models that enhance our understanding of CCX characteristics and drivers. These models are crucial for predicting future changes and implementing effective conservation strategies. They also serve as a vital tool for policymakers and environmental planners as they prepare to mitigate the effects of these changes.

Summing Up

The findings from the study serve as a clarion call for immediate action. Protecting our oceans from compound extremes requires global cooperation and innovative solutions aimed at reducing greenhouse gas emissions and enhancing marine conservation efforts. This research provides a foundation for understanding the scale of the problem and outlines the critical areas for needed interventions.

The preservation of marine biodiversity and the sustainability of our global ocean ecosystems depend on our ability to respond effectively to the challenges posed by climate change. Through informed policy-making and collaborative international efforts, there is hope for mitigating the impact of these profound marine disturbances.

Source: Wong, J., Münnich, M., & Gruber, N. (2024). Column‐Compound Extremes in the Global Ocean. Journal of Oceanic Studies, 5(3). https://doi.org/10.1029/2023AV001059.

Understanding the Impact of Climate Change on Marine Mammals

/ activist360
Mother and baby sperm whale
A mother sperm whale and her calf off the coast of Mauritius. The calf has remoras attached to its body. Credit: Gabriel Barathieu, January 26, 2013.

Our oceans are suffering the impact of climate change. From inshore environments to the deep ocean, marine ecosystems are undergoing significant transformations due to rising temperatures, increased carbon dioxide levels, and shifting environmental conditions. This research article by National Oceanic and Atmospheric Administration (NOAA) researchers published in PLOS ONE delves into the intricate relationship between climate change and marine mammals. The study focused on the United States’ western North Atlantic (WNA), Gulf of Mexico (GOMx), and Caribbean waters.

Drivers Impacting Marine Life

Global climate change has ushered in a multitude of alterations that stem from a handful of key drivers. Rising levels of heat and carbon dioxide in the Earth’s atmosphere are at the forefront. Here’s a closer look at the other major factors:

1. Increasing Ocean Temperatures

As the Earth’s temperature rises, so too do the temperatures of our oceans. This phenomenon is particularly evident in the western North Atlantic (WNA), where sea surface temperatures have been increasing rapidly. These rising temperatures have direct and indirect consequences for marine mammals that call these waters home.

2. Rising Sea Levels

One of the most visible effects of climate change is the rise in sea levels. This phenomenon is especially pronounced in regions like the southeastern United States, Gulf of Mexico (GOMx), and the Caribbean Sea. The accelerating sea level rise poses a significant threat to coastal ecosystems and the marine life they support.

3. Decreasing Dissolved Oxygen

Climate change also contributes to declining levels of dissolved oxygen in our oceans. This is a particularly alarming trend for marine mammals, as many of them rely on oxygen-rich environments to thrive.

4. Declining Sea Ice Coverage

In polar regions, the decline in sea ice coverage is a stark indicator of climate change. This has profound implications for marine mammals like polar bears and seals, which depend on sea ice as a platform for hunting and resting.

5. Ocean Acidification

The increasing levels of carbon dioxide in the atmosphere are not only raising temperatures but also leading to ocean acidification. This can have devastating effects on marine life, particularly species with calcium carbonate shells or skeletons.

6. Shifting Precipitation Patterns

Climate change also drives changes in precipitation patterns, impacting the salinity of ocean waters. These shifts can have cascading effects on marine ecosystems and the species that inhabit them.

Impacts on Marine Mammals

The effects of climate change are not limited to the physical environment; they also dramatically affect marine communities, including marine mammals. Here are some of the key ways in which climate change impacts these majestic creatures:

1. Altered Distribution and Behavior

Marine mammal species with restricted geographical distributions and habitat tolerances are particularly vulnerable. The changing conditions of their environment leave them with limited opportunities to adapt.

2. Disrupted Prey Availability

Marine mammals rely on stable environments where prey availability is relatively predictable. Climate change can disrupt these ecosystems, leading to food scarcity and challenges in feeding.

3. Climate-Related Shifts in Distribution

Some marine mammal populations, such as ice-associated seals and subarctic cetaceans, have already shown shifts in distribution due to climate change. These changes have significant implications for their conservation and management.

4. Predictive Challenges

Predicting climate-driven changes in marine mammal distribution, phenology, and abundance is a complex task. However, advancements in modeling tools and approaches are improving our ability to make informed predictions.

Assessing Climate Vulnerability

Understanding the vulnerability of marine mammals to climate change is crucial for their conservation. Climate vulnerability assessments (CVAs) play a pivotal role in identifying species at risk. These assessments take into account factors such as exposure, sensitivity, and adaptive capacity.

Trait-Based CVAs

One approach to CVAs involves trait-based assessments, which consider the biological or ecological traits of species that are linked to climate responses. While this method provides less resolution than quantitative approaches, it offers a rapid and adaptable way to assess vulnerability.

NOAA’s Role in Marine Mammal Protection

In the United States, the NOAA has a mandate to protect and recover marine mammal species under the Endangered Species Act (ESA) and Marine Mammal Protection Act (MMPA). To address climate-related threats to marine mammals, NOAA conducts trait-based CVAs for stocks in the WNA, GOMx, and Caribbean waters.

Conclusion

Climate change presents a profound challenge to marine mammals in the United States’ WNA, GOMx, and Caribbean waters. It is a complex issue that requires a multifaceted approach to address. As the world grapples with the consequences of a changing climate, it is imperative that we prioritize the conservation and protection of these incredible creatures. NOAA’s efforts, including trait-based CVAs and vulnerability rankings, provide valuable tools for understanding and mitigating the effects of climate change on marine mammals.

By comprehensively assessing vulnerability and taking proactive measures, we can work towards safeguarding the future of our marine mammal populations.

Source: Lettrich, M.D. et al. (2023). Vulnerability to climate change of U.S. marine mammal stocks in western North Atlantic, Gulf of Mexico, and Caribbean. PLoS ONE, 18(9), e0290643.

Despite shrinking ‘Dead Zone’, Gulf Coast grapples with massive fish die-off

/ activist360
A shrimp boat trawls for shrimp in the Gulf of Mexico. (Image credit: NOAA Fisheries)
A shrimp boat trawls for shrimp in the Gulf of Mexico. (Image credit: NOAA Fisheries)

NOAA anticipated a remarkably smaller ‘Dead Zone’ in Gulf of Mexico this summer

The National Oceanic and Atmospheric Administration (NOAA) predicted a “dead zone” in the Gulf of Mexico this summer, an oxygen-deprived area spanning about 4,155 square miles that can prove lethal to marine life. This estimate, while significant, is lower than the 36-year average of 5,364 square miles. The dead zone occurs annually due to excessive nutrient pollution from human activities within the Mississippi River watershed.

The US Geological Survey (USGS) tracks key factors such as river discharge and nutrient loading, which contribute to the dead zone. In May 2023, there was a 33% decrease in river discharge, a 42% decrease in nitrate, and a 5% decrease in phosphorus levels compared to the long-term averages from 1980 to 2022. These nutrients instigate an algal bloom that, upon death and decay, depletes water oxygen levels, endangering marine life, especially bottom-dwelling species.

NOAA’s hypoxia forecasts are designed to help coastal managers and stakeholders proactively mitigate the impacts of hypoxia. The data also inform nutrient reduction targets aimed at curbing future dead zones. The Interagency Mississippi River and Gulf of Mexico Hypoxia Task Force aims to reduce the dead zone to 1,900 square miles by 2035.

Despite smaller ‘Dead Zone’, thousands of fish perish on Texas Gulf Coast

The New York Times along with several other media outlets reported that on Friday, tens of thousands of fish started washing ashore along the Texas Gulf Coast due to a combination of environmental conditions that depleted oxygen levels in the warm waters. The incident was described as a “perfect storm” of poor conditions by Bryan Frazier, the director of Brazoria County Parks Department. Warm water holds less oxygen than cold water, and the calm, cloudy weather obstructed the usual ways oxygen is infused into ocean water. The fish are thought to have been trapped in shallow, warm water where the oxygen supply diminished.

Experts suggest that climate change could be contributing to such incidents as warmer waters become more common. Katie St. Clair, the sea life facility manager at Texas A&M University at Galveston, said that rising water temperatures could lead to more such events, especially in shallow, near-shore environments.

Frazier noted that these fish kills are not uncommon during warmer periods and predicted local water conditions would improve as ocean waves reintroduce oxygen and fish leave low-oxygen areas. However, the United Nations reported in 2019 that warmer ocean waters have increased incidences of hypoxia (low oxygen levels), posing threats to fish populations.

The fish kill could significantly impact the environment as the dead fish, primarily Gulf menhaden, play a crucial role in the local ecosystem. Clean-up operations are ongoing to prevent the dead fish from rotting in the midday heat.