In 2022, the Great Barrier Reef experienced its fourth mass bleaching event in the last seven years, and a NASA report revealed sea level rise is accelerating. Although climate change’s impact on the world’s oceans was the biggest marine story of the year, plenty of other amazing saltwater milestones deserve attention. Scientists found that the largest plant in the world is a seagrass and that 60 million icefish nest together off the coast of Antarctica. Researchers also added a piece to the puzzle of one of the world’s most mysterious animal migrations and witnessed the record impact of an underwater eruption.
In case you’ve missed any of the biggest saltwater happenings, the National Museum of Natural History’s Ocean Portal team has rounded up the biggest ocean stories of the year here.
A slippery eel was pinned down
Since the 1980s, the European eel has experienced a 98 percent decline in its population, putting it on the International Union for Conservation of Nature’s critically endangered list. Any new information about the animal’s life cycle—it lives in both fresh water and salt water—will help fishery managers save the eel from extinction. But the species has been vexing naturalists and scientists for millennia.
The complicated life cycle of the eel has made it difficult for scientists to understand their reproductive biology, including the suspected mysterious trans-Atlantic migration all eels make at the tail end of their life. This year scientists were finally able to track, via satellite tags, five European eels on their journey from the Azores to the Sargasso Sea. Prior to this discovery, the understanding that eels travel to the Sargasso Sea was based on a 1922 study about their larvae—that’s where the smallest larvae were found, so it was believed that was where they hatch. No spawning eels nor eggs had ever been found in the Sargasso Sea, making this discovery a remarkable accomplishment for scientists trying to understand the eels so they can aid the animal’s recovery.
Authorities halt a fishing season
The Discovery Channel’s television show “Deadliest Catch” brought the perils of crabbing to the awareness of die-hard landlubbers, but now that fishing industry is in danger of becoming a thing of the past. For the first time, the snow crab fishing season was shut down due to a near collapse of the crab population. National Oceanic and Atmospheric Administration (NOAA) scientists attribute the disappearance of the crabs to climate change, though they are unsure whether warming water has moved the crabs from their historic living area, inhibited larvae development, introduced new diseases or had some other effect. According to NOAA, average annual revenue of the industry is about $100 million per year, and the loss of the industry will leave commercial fishing families without their primary source of income while the season is closed.
Researchers identified the world’s largest plant
In the coastal waters of Shark Bay, Australia, scientists discovered that a seagrass bed of Poseidon’s ribbon weed (Posidonia australis) is actually one plant. The massive organism covers an area of 77 square miles. Scientists began surveying the bed’s genetic code to determine how genetically diverse the seagrasses were and found that every single shoot was genetically identical; they were all clones. This means that over time the seagrass grew from an initial seed into one large bed. The growth rate of Poseidon’s ribbon weed is about 14 inches a year, meaning the seagrass bed took 4,500 years to grow to its current size.
Scientists discovered a fish metropolis
An expedition to the bottom of the ocean off the coast of Antarctica revealed a shocking surprise, as detailed in a January 2022 study in Current Biology. Scientists discovered 60 million icefish nests covering an area the size of a small city. Previously discovered sites had a maximum of only about 60 nests. Scientists were initially interested in this section of the Weddell Sea because it features an area of significant upwelling, a place where deep water moves up to the surface. The bottom layer of water at the seafloor is more than 3 degrees Fahrenheit warmer than the surrounding area. The RV Polarstern towed a large camera device across the seafloor, and what scientists saw blew them away. There was nothing but fish nests for as far as the eye could see. Scientists believe the nesting icefish are taking advantage of the warmer water to help incubate their eggs.
Researchers found Endurance
Ernest Shackleton famously led his crew to safety on a voyage to Antarctica in 1915 following the devastating loss of his vessel—the Endurance—after it was crushed by an ice floe. For over a century, the fate of the ship has been a mystery, but this year a determined group of explorers found the location of the wreck. Researchers aboard the S.A. Agulhas II used two submersibles to scour the seafloor across a 150-square-mile area. After two weeks of searching, they found the vessel residing 9,842 feet below the surface in the middle of the Weddell Sea—even though it was covered in anemones and various other deep-sea creatures. Researchers and explorers around the globe celebrated the discovery, noting the difficulty of such an undertaking in such remote and treacherous waters.
A deadly eruption rocked Tonga
In January of this year, the underwater volcano Hunga Tonga-Hunga Haʻapai near Tonga in the South Pacific erupted ash and water 35 miles into the atmosphere—the highest plume ever recorded. The massive eruption sent tsunami waves across the Pacific and an atmospheric shock wave around the globe several times over. Sadly, six people from Tonga died, though the remoteness of the explosion likely limited casualties.
The plume rose so high that it broke into the mesosphere. Rather than using the standard method for measuring the height of the ash, scientists turned to stationary weather satellites, which photographed the plume from multiple angles over time. Such technology has only been available in the last decade, and it helped researchers learn crucial information about the dramatic oceanic eruption. Very little is known about underwater volcanoes when compared to their terrestrial counterparts, and the innovative research helped fill in some gaps.
COP27 went blue
Climate change’s impacts on oceans aren’t just a drop in the bucket. Our seas are becoming warmer and more acidic—and melting sea ice is leading to global sea level rise. At the United Nations Climate Change Conference, or COP27, held this November in Egypt, many ocean problems and some possible solutions came into focus.
Scientists announced that summers with no Arctic Ocean sea ice are pretty much a guarantee, no matter the efforts made to reduce carbon in our atmosphere. This means new shipping paths will be reliably open, but it also means that species that thrive on sea ice will have to adapt significantly and may suffer. Despite reports that highlighted the negative impacts of a warming climate on the ocean, hope was on the menu at the conference as well. The United States and Norway launched a Green Shipping Challenge, which encourages governments, ports and companies to transform the industry via sustainable methods and green technologies. And the Global Mangrove Alliance in collaboration with the U.N. Climate Change High-Level Champions launched a Mangrove Breakthrough goal to provide a framework for the restoration and protection of this all-important ecosystem. For the first time, the conference featured an Ocean Pavilion so participants could explore how the ocean will be impacted by climate change.
Scientists fill in details of fish evolution
Archaeologists uncovered two fossil deposits, or “beds,” in China brimming with specimens that help fill in gaps in our knowledge of how fish evolved. The diverse fossils—which are more than 400 million years old—included the earliest known complete jawed fish, a cartilaginous fish related to later sharks and rays with unusual armor-like plates, and a jawless fish with fins that could be the precursor to arms and legs of land animals. The study revealing these finds, published this past September, emphasizes that scientists still have a lot to learn about the evolution of jawed vertebrates. Likewise, we have much more to discover about the marine ecosystems such creatures inhabit.