Brad Seibel still remembers the headlines from 20 years ago that sounded like a B-rated science fiction movie: “Invasion of the jumbo squid in Monterey Bay” and the like. He was a postdoctoral researcher at the Monterey Bay Aquarium Research Institute (MBARI) at the time.
It was anything but fiction. Traditionally living in more tropical latitudes, the voracious eaters came in record numbers from Central California — fattening their bellies with hake, redfish and other commercially important species to the dismay of local fishermen. Scientists thought their arrival was related to a combination of climate change and overfishing, but the details were vague.
Seibel, now a professor and expert in marine physiology at the USF College of Marine Science, recently published a paper in Nature Climate Change that sheds light on those long-ago headlines. It connects the dots on animal metabolism he’s collected over 20 years and seven research cruises in the Gulf of California, Mexico, and adds another chapter to the story of how some animals may be responding to the warming oceans.
“The basic story of recent years has been that as the ocean warms and loses oxygen, animals in it will be driven from their native habitats and moved to cooler waters at more northern latitudes,” Seibel said. “But this is too much of a simplification.”
Not all sea creatures respond to changing conditions in the same way.
Seibel co-authored the publication with his former graduate student, Matt Birk, now a professor at Saint Francis University in Pennsylvania. The study is the first to delve deeper into the relationship between oxygen, temperature and the metabolic needs of vertical migratory birds, including billions of marine animals, from tiny crustaceans called krill to the six-foot-long jumbo squid. Seibel and Birk used modeling to understand how six species of krill and the jumbo squid would respond metabolically to the different parameters approaching day and night habitats.
“Vertical migrators oppose the basic story, which is largely based on studies of coastal animals,” Seibel said.
As the oceans warm, squid and other vertical migratory birds living in tropical zones are likely to expand their habitat northward, but not necessarily leave their native tropical zones.
That probably happened in Monterey 20 years ago, Seibel said. An El Nino event temporarily brought warmer water to the coast. (Think of it as a relatively short-lived model of climate change.) Warmer waters allowed the squids to expand their range northwards, where they took advantage of new food sources—with major implications for local fisheries—even though food was plentiful at the time. more tropical latitudes.
“It wasn’t that they didn’t have enough oxygen or that it was too hot for them further south; before the El Nino event, it was too cold for them in the north” — a nuance to their metabolic requirements that there was. matter, Seibel said.
Vertical migratory birds live very differently from coastal species, which experience a fairly constant supply of oxygen in waters that are well mixed with the atmosphere. Migrators live at depth during the day, where it is cold and dark and there is less oxygen, and they travel hundreds of meters at night to the relatively warm ocean surface to eat, where oxygen is abundant and when it is safer to forage.
“This study is a good example of the fact that the conclusions we often draw from well-studied — and easily captured — organisms may not hold true for the greater diversity of species and lifestyles in the oceans,” Birk said.
It turns out that the effect of temperature on the metabolism of vertical migratory birds is 4-5 times greater than for most coastal species. For example, the squid does not do much at depth. When migrating to shallower water for a meal, their metabolism skyrockets, Seibel said.
Modeling that includes increased effects of temperature on the metabolism of vertical migratory birds suggests that climate change will expand the available habitat for vertical migratory birds north and south by as much as 10-20 degrees latitude by the end of the century, Seibel said.
“We really need to delve into animal physiology and better understand how different species evolve and adapt to environmental conditions,” Seibel said.
Addressing the ocean’s deoxygenation crisis
Brad A. Seibel et al, Unique thermal sensitivity imposes a cold water energetic barrier to vertical migratory birds, Nature Climate Change (2022). DOI: 10.1038/s41558-022-01491-6
Quote: Warming oceans are likely to shrink the viable habitat of many marine creatures — but not all (2022, Oct. 18) retrieved Oct. 18, 2022 from https://phys.org/news/2022-10-oceans-viable-habitat-marine – animalbutt.html
This document is copyrighted. Other than fair dealing for personal study or research, nothing may be reproduced without written permission. The content is provided for informational purposes only.