Latest news with #phytoplankton
Yahoo
16 hours ago
- Science
- Yahoo
As the ocean warms, a new study found it's also changing color
For thousands of years, writers have come up with increasingly creative ways to describe the 'wine-dark sea.' But a new study suggests that modern poets may be faced with a slightly different palette. A study published Thursday in the journal Science found that the ocean is changing color as it warms. By analyzing satellite data from 2003 to 2022, researchers from Duke University and the Georgia Institute of Technology noticed that waters near the equator were getting bluer, while areas near the poles were turning greener. Lead author Haipeng Zhou calls it 'this greener greens or bluer blues phenomenon.' The culprit, the paper suggests, is the teeny tiny plant-like creatures that form the building blocks of the marine food web — phytoplankton. Phytoplankton are filled with a green pigment called chlorophyll that allows them to absorb energy from sunlight through photosynthesis. As waters near the equator warm, they're less hospitable to the microscopic critters, so the water appears bluer. At the poles, the colder water is far more nutrient-dense, so there's lots more phytoplankton to go around, giving the waters a rich, green tinge. It's not a new phenomenon. There's a reason the Caribbean is known as the land of dazzling turquoise waters, while Arctic waters are a dark teal contrast to the ivory ice floes around them. But Zhou, who began the research at Duke University and completed it as a postdoctoral researcher at Georgia Tech, found that as the ocean warms, this phenomenon is getting stronger. Their study only looked at the open ocean, not coastal waters. Near the coast, there are plenty of complicating factors that make it hard to clearly point to phytoplankton as the main cause of color changes, like dirt and sand floating in the water, shifting winds, pollution or even seagrass die off. To understand the concentrations of phytoplankton, the research team relied on a National Oceanic and Atmospheric Administration database made up of samples scooped from various research cruises all over the world. This database, plus satellite imagery, helped show the color shift in different regions of the ocean. The changing levels of phytoplankton could be bad news for fish in the tropics, or for communities that rely on those fish. But it could also be a boon for their northern and southern cousins. 'We all know that phytoplankton is the bottom of the food chain. Any impact on phytoplankton will have impacts on its predators,' Zhou said. Phytoplankton need sun and nutrients to flourish, but when the ocean warms, the individual layers that make up the sea grow more stratified, so it's harder for phytoplankton to float up and down the water column to access the same light and nutrients they're used to, he said. So while scientists can clearly say that warmer waters lead to fewer phytoplankton, and they know that climate change is one of the main reasons the oceans are heating up, it's not clear if climate change is the reason for the color shift. 'We need longer records, 30 years, 40 years, to make us more confident whether it is linked to climate change or global variability,' Zhou said. The study only looked at about 20 years of data, which Zhou said is enough to confidently say that something has changed, but not long enough to know what caused that change. Other factors can and do affect water temperature, like the shift in trade winds over the Atlantic that led to a coral-killing marine heat wave in 2023. 'The study period was too short to rule out the influence of recurring climate phenomena such as El Niño,' wrote co-author Susan Lozier, Dean of the College of Sciences at Georgia Tech, in a statement. However, Zhou added, more research may very well find that this color-shifting trend continues into the future as human-caused climate change continues to heat up the oceans. 'The temperature of the water is rising. While there's no evidence showing that this progress will slow down, it's very likely we'll have warmer waters in the future, which means we'll have a continuous impact on the ocean ecosystem.' Correction: An initial version of this story incorrectly listed the start of the period analyzed on satellite as 2009. It was 2003.
Yahoo
18 hours ago
- Science
- Yahoo
The ocean is changing colors, researchers say. Here's what it means.
Warming waters are causing the colors of the ocean to change -- a trend that could impact humans if it were to continue, according to new research. Satellite data shows that ocean waters are getting greener at the poles and bluer toward the equator, according to a paper published Thursday in the journal Science. MORE: How penguin poop can help to mitigate climate change The change in hue is being caused by shifting concentrations of a green pigment called chlorophyll, which is produced by phytoplankton, Haipeng Zhao, a postdoctoral researcher and lead author of the paper, told ABC News. Phytoplankton are photosynthetic marine organisms. As algae, phytoplankton has photosynthetic pigments, which absorb green light and cause the waters around it to appear primarily green, Susan Lozier, dean of the College of Sciences at the Georgia Institute of Technology and co-author of the paper, told ABC News. Where phytoplankton are absent, the water appears blue. The researchers analyzed satellite data on the open ocean collected from 2003 to 2022 by a NASA instrument that combs through the planet every two days to measure light wavelength, according to the paper. The presence of chlorophyll in open ocean is a proxy for concentrations of phytoplankton biomass. The colors indicate how chlorophyll concentration is changing at specific latitudes, in which the subtropics are generally losing chlorophyll, and the polar regions -- the high-latitude regions -- are greening, the researchers said. MORE: Global sea level rose faster than expected in 2024, according to NASA analysis Green areas became greener, especially in the northern hemisphere, and blue regions "got even bluer," according to a press release by Duke University. "We borrowed concepts from economics called the Lorenz curve and the Gini index, which together show how wealth is distributed in a society," said Nicolas Cassar, the Lee Hill Snowdon Bass chair at Duke University's Nicholas School of the Environment, in a statement. "So, we thought, let's apply these to see whether the proportion of the ocean that holds the most chlorophyll has changed over time." The researchers examined how the patterns they observed were affected by variables like sea surface temperature, wind speed, light availability and mixed layer depth. Warming seas correlated with changes in chlorophyll concentration, they found. The other variables did not show any significant associations to chlorophyll concentration. However, the findings cannot be solely attributed to climate change, the authors said. The study period was too short to rule out the influence of recurring climate phenomena, Lozier said. "We haven't been able to observe the ocean for decades and decades, just because the satellite technology is pretty new," Lozier said. MORE: How marine biologists are using elephant seals as nature's 'artificial intelligence' After focusing his Ph.D. on regional studies in high-latitude oceans, Zhao said he was inspired to dive deeper to see whether oceans were transforming in color throughout the rest of the world. "The ocean has been warming, so there's a big question then about, what are the biological consequences of the ocean warming?" Lozier said. Several studies since the 1990s have documented enhanced greening on land, attributed to average leaf color increasing due to rising temperatures and other factors, according to the researchers. However, documenting such changes in the ocean has proven to be more difficult. The satellite images provide data on the chlorophyll production at the surface, but the picture is still incomplete, the researchers said. MORE: How to turn ocean waves into renewable energy If the trend continues, marine food webs could be impacted, the researchers said. Since phytoplankton are at the base of the food chain, it can be used to determine the presence of fish, too, Lozier said. A persistent decline in phytoplankton near the equator could cause a redistribution of the location of fisheries, the authors said. This could be especially impactful in low to middle-income nations, such as the Pacific Islands, that rely on commercial fishing for food and economic development, the authors said.
Yahoo
4 days ago
- Science
- Yahoo
How Chinese, US coal plants are changing Hawaiʻi's waters
HONOLULU (KHON2) — Even if you are far from a factory, the ocean can still feel its smoke. A new study led by scientists at the University of Hawai'i at Mānoa shows that iron from burning coal and making steel is drifting into the North Pacific Transition Zone, just north of Hawai'i, changing the way life works here and the health of our entire ecosystem. This ocean region is a key part of the Pacific food web. It's where tiny ocean plants called phytoplankton grow each spring, and these phytoplankton feed many fish and other marine animals. 10 facts about the remote island known as the 'Hawaiʻi of Japan' Iron is a key nutrient for phytoplankton; but too much of it, especially from human activity, is throwing things out of balance. Here's what the UH study has found: In photos, Waikīkī Beach in the 1940s and 1950s Each spring, the phytoplankton in our part of the ocean are hungry for iron. When extra iron enters the water, it sparks a big bloom of growth. At first, that may sound like a good thing; but it comes at a cost. When the bloom happens too fast, other nutrients in the water get used up too quickly. That makes the bloom crash later in the season. When the bloom prematurely collapses, it harms fish and the fisheries that depend on them. Lilo & Stitch summer: Hawaiʻi to expect huge tourism numbers Nick Hawco, assistant professor in the Department of Oceanography at UH Mānoa, explained how these changes affect life across our ocean. 'The ocean has boundaries that are invisible to us but known to all sorts of microbes and animals that live there,' Hawco said. 'The North Pacific Transition Zone is one of these boundaries. It divides the low nutrient ocean gyres from the high nutrient temperate ecosystems to the north.'The added iron causes that boundary to shift north. As the ocean also gets warmer, the waters rich in phytoplankton are moving farther away from Hawai'i. 'It's a one-two punch: industrial iron is impacting the base of the food web and the warming of the ocean is pushing these phytoplankton-rich waters further and further away from Hawai'i,' Hawco said. A study led by the University of Southern California (USC) investigated how industrial emissions from East Asia, particularly from coal-fired power plants, contribute iron to the North Pacific Ocean and how this is affecting marine ecosystems. Here's what they found: Iron can travel thousands of miles: The research demonstrates that iron particles from industrial emissions in East Asia can be transported across the Pacific Ocean by westerly winds where the iron is deposited in the North Pacific Ocean. Industrial iron isn't the same as natural iron: Scientists identified that the iron found in the ocean matched the isotopic signature of industrial emissions, distinguishing it from natural sources like mineral dust. Phytoplankton are small but powerful: Phytoplankton, the microscopic plants in the ocean, form the base of the marine food web. The study highlights that increased iron availability can stimulate their growth, which is crucial for marine ecosystems and global carbon cycles. The ocean has invisible boundaries: The introduction of iron into the ocean can shift ecological boundaries and affect nutrient distribution and marine life. The study notes that such changes can impact the North Pacific Transition Zone, which is a critical area for marine biodiversity. Fisheries near Hawai'i could suffer: The research indicates that the influx of iron could alter phytoplankton distribution. This can potentially affect fish populations and fisheries near Hawai'i. You can click for the UH study and for the USC study. Get news on the go with KHON 2GO, KHON's morning podcast, every morning at 8 Both of these studies underscore the complex and far-reaching impacts of industrial pollution on marine ecosystems, even in remote regions like Hawaiʻi. Copyright 2025 Nexstar Media, Inc. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.
The Guardian
27-05-2025
- Science
- The Guardian
Planet's darkening oceans pose threat to marine life, scientists say
Great swathes of the planet's oceans have become darker in the past two decades, according to researchers who fear the trend will have a severe impact on marine life around the world. Satellite data and numerical modelling revealed that more than a fifth of the global ocean darkened between 2003 and 2022, reducing the band of water that life reliant on sunlight and moonlight can thrive in. The effect is evident across 75m sq km (30m sq miles) of ocean, equivalent to the land area of Europe, Africa, China and North America combined, and disturbs the upper layer of water where 90% of marine species live. Dr Thomas Davies, a marine conservationist at the University of Plymouth, said the findings were a 'genuine cause for concern', with potentially severe implications for marine ecosystems, global fisheries and the critical turnover of carbon and nutrients in the oceans. Most marine life thrives in the photic zones of the world's oceans, the surface layers that allow sufficient light through for organisms to exploit. While sunlight can reach a kilometre beneath the waves, in practice there is little below 200 metres. This upper band of water is where microscopic plant-like organisms called phytoplankton photosynthesise. The organisms underpin virtually all marine food webs and generate nearly half the planet's oxygen. Many fish, marine mammals and other creatures hunt, feed and reproduce in the warmer waters of the photic zones where food is most abundant. Davies and his colleagues drew on satellite data and an algorithm used to measure light in sea water to calculate the depths of photic zones around the world. Darkening affected 21% of the global ocean in the 20 years to 2022. In 9% of the ocean, this led to photic zones being 50 metres shallower, while in 2.6% of the ocean, the zones were 100 metres shallower. Details of this study appear in Global Change Biology. The oceans darken when light finds it harder to penetrate the water. It is often seen along coastlines where upwellings of cold, nutrient rich water rise to the surface, and where rainfall sweeps nutrients and sediments from the land into the water. The drivers for darkening far offshore are less clear, but global heating and changes in ocean currents are thought to be involved. 'The areas where there are major changes in ocean circulation, or ocean warming driven by climate change, seem to be darkening, such as the Southern Ocean and up through the Gulf Stream past Greenland,' Davies said. Despite an overall darkening, about 10% of the ocean, or 37 million sq km, became lighter over the past 20 years, the study found. Off the west coast of Ireland, for example, a very large area of ocean has brightened, but further out it has darkened. 'Marine organisms use light for a whole variety of purposes. They use it for hunting, for mating, for timing reproductive events. They use it for basically every single part of their biology,' said Davies. 'With ocean darkening, they have to move up the water column, and there is less space, they're all being squished up towards the surface.' Prof Oliver Zielinski, the director of the Leibniz Institute for Baltic Sea Research in Germany, said the darkening of vast ocean areas was a 'worrying trend'. 'Such changes can disrupt marine food webs, alter species distributions, and weaken the ocean's capacity to support biodiversity and regulate climate,' he said. 'Coastal seas, being closest to human activity, are particularly vulnerable, and their resilience is crucial for both ecological health and human wellbeing.'
