The Atlantic ocean is changing to brown

Something Huge and Brown is taking over the Atlantic Ocean : Record 37.5 Million tons of toxic seaweed suffocates Caribbean beaches 

Since 2011, a monstrous structure has taken shape in the Atlantic Ocean almost every year, sprawling from the West African coast to the Gulf of Mexico. It’s the Great Atlantic Sargassum Belt, a gargantuan bloom of a brown free-floating seaweed. In May, the seaweed belt hit a record biomass of 37.5 million tons. In a study, researchers from Florida Atlantic University’s (FAU) Harbour Branch Oceanographic Institute outline the rapidly growing seaweed’s development during the last four decades. Unsurprisingly, human activity is involved in a widespread ecological change. A vast and perplexing brown tide is sweeping across the Atlantic Ocean, alarming scientists as it disrupts ecosystems and threatens coastal communities from Africa to the Americas. Some of the important points are as follows:-

 A massive brown tide known as the Great Atlantic Sargassum Belt is spreading across the Atlantic Ocean.

The phenomenon highlights the interconnectedness of global ecosystems and the impact of human actions.

Coastal communities face economic and health risks as the seaweed clogs beaches and releases harmful gases.

Scientists link the growth to human activities which introduce excessive nutrients into the ocean.

A peculiar ecological phenomenon is sweeping across the Atlantic Ocean, drawing the attention of scientists and policymakers alike. This vast expanse of floating seaweed, known as the Great Atlantic Sargassum Belt, is not merely a natural curiosity but a potent indicator of the profound ways human activities are reshaping marine environments. The bloom, which now stretches from West Africa to the Gulf of Mexico, has reached unprecedented levels, posing significant challenges to coastal communities and ecosystems. As researchers strive to understand this phenomenon, the implications for our oceans, and the people who rely on them, are becoming increasingly urgent. The influx of nutrients from major rivers, including the Mississippi and the Amazon, acts as a catalyst for this growth. Researchers have identified these rivers as key drivers of the bloom’s expansion, providing the necessary nutrients which allow sargassum to thrive. The scale of this bloom is unprecedented, with the biomass reaching a record 37.5 million tons recorded recently. This massive accumulation of seaweed is reshaping entire ocean basins and challenging our understanding of marine ecosystems.

The Great Atlantic Sargassum Belt has been expanding dramatically, transforming from a localized phenomenon into a massive oceanic bloom. This belt of floating sargassum has spread from its traditional habitat in the Sargasso Sea to encompass a vast swath of the Atlantic Ocean. Ocean currents like the Loop Current and the Gulf Stream play a crucial role in this expansion, distributing nutrient-rich waters which fuel the seaweed’s growth. Satellite imagery has captured the rapid increase in sargassum biomass, doubling in just days under optimal conditions. “The expansion of sargassum isn’t just an ecological curiosity, it has real impacts on coastal communities. The massive blooms can clog beaches, affect fisheries and tourism, and pose health risks,” Brian Lapointe, lead author of the study and a marine scientist at FAU Harbor Branch, said. “Understanding why sargassum is growing so much is crucial for managing these impacts,” he added. “Our review helps to connect the dots between land-based nutrient pollution, ocean circulation, and the unprecedented expansion of sargassum across an entire ocean basin.”

The surge in sargassum biomass can be traced back to human activities which introduce excessive nutrients into the ocean. According to Brian Lapointe, land-based nutrient inputs are the primary drivers of this growth. Agricultural runoff, wastewater discharge and atmospheric deposition contribute to the nutrient-rich conditions which favour sargassum blooms. The chemical composition of sargassum has changed over the years, with nitrogen levels increasing significantly while phosphorus has declined. This shift indicates the profound impact of terrestrial processes on marine ecosystems. By altering the nutrient balance in the ocean, human activities are reshaping the growth patterns of marine species, with sargassum being a prime example. The seaweed’s ability to thrive in nutrient-poor waters by recycling marine waste further complicates management efforts and underscores the interconnectedness of terrestrial and marine ecosystems. Scientists previously believed that sargassum was mostly limited to the Sargasso Sea’s nutrient-poor waters. More recent research, however, has revealed the organism to be quite the traveller, tracing sargassum’s movement from nutrient-rich coastal areas, such as the western Gulf of Mexico, to the open ocean, hitching a ride on the Loop Current (one of the fastest currents in the Atlantic) and the Gulf Stream. In the open ocean, nutrients are usually concentrated at great depth.

The spread of the Great Atlantic Sargassum Belt has far-reaching consequences for coastal communities. The dense mats of seaweed can clog beaches, disrupt fisheries and pose health risks to local populations. Popular tourist destinations in the Caribbean, Mexico and Florida have experienced significant economic losses due to emergency clean-ups and decreased tourism revenue. Sargassum blooms also create oxygen-depleted zones beneath the dense mats, affecting marine life and fisheries. The decomposing seaweed releases hydrogen sulfide gas, which can cause respiratory problems for nearby residents. In extreme cases, such as the 1991 shutdown of a Florida nuclear power plant, the impacts of these blooms have disrupted critical infrastructure. As the belt continues to expand, these disruptions are likely to become more frequent, posing on going challenges to coastal economies and public health. In 2004 and 2005, satellite imagery revealed massive sargassum windrows, long bands of floating sargassum, in the western Gulf of Mexico, a region where rivers, including the Mississippi and Atchafalaya, are increasingly dumping nutrients. 

Understanding the dynamics of sargassum growth requires an examination of its nutrient composition over time. Researchers have studied the changes in nitrogen, phosphorus, and carbon levels across different regions of the Atlantic to identify the environmental forces driving this phenomenon. Factors such as river flows, rainfall and Amazon basin floods play a significant role in influencing the bloom’s biomass. In fact, research since the 1980s revealed that the seaweed grows faster and is more productive in shallow nutrient-rich waters than nutrient-poor open ocean waters. In other words, more nutrients mean more sargassum. In certain conditions, the biomass of Sargassum natans and Sargassum fluitans can increase twofold within few days. By analysing the nutrient composition of sargassum, scientists are gaining insights into the complex interactions between terrestrial and marine ecosystems. The seaweed’s ability to adapt to varying nutrient levels and recycle marine waste highlights its resilience and complicates management strategies. As researchers continue to investigate the factors driving sargassum growth, the findings hold important implications for understanding how human activities influence marine environments on a global scale.

Phosphorus and nitrogen are crucial nutrients for sargassum. From the 1980s to the 2020s, while the seaweed’s nitrogen content rose by over 50%, its phosphorus declined. “These changes reflect a shift away from natural oceanic nutrient sources like upwelling and vertical mixing, and toward land-based inputs such as agricultural runoff, wastewater discharge and atmospheric deposition,” Lapointe explained. In other words, human activity. Carbon levels in sargassum are creeping upwards, demonstrating how outside nutrients are changing its makeup and affecting ocean plant life, he added. The team also highlights, however, that sargassum windrows are able to also grow in nutrient-poor waters by recycling nutrients in marine animal poop, among other methods. The Great Atlantic Sargassum Belt serves as a stark reminder of the interconnectedness of global ecosystems. The bloom’s expansion reflects how human activities, such as nutrient pollution from agriculture and urban development, can have far-reaching impacts on marine environments. As scientists work to unravel the complexities of this ecological phenomenon, the broader implications for ocean health and coastal communities remain a pressing concern. 

“Our review takes a deep dive into the changing story of sargassum, how it’s growing, what’s fuelling that growth, and why we’re seeing such a dramatic increase in biomass across the North Atlantic,” Lapointe explained. “By examining shifts in its nutrient composition, particularly nitrogen, phosphorus and carbon, and how those elements vary over time and space, we’re beginning to understand the larger environmental forces at play.” The study is just one more example of how human activity is driving deeply rooted ecological changes, with the extent of its farthest-reaching consequences still terrifyingly unknown to the world around us.