Saving Seafood

Phytoplankton blooms offer insight into impacts of climate change

March 23, 2023 — The first study into the biological response of the upper ocean in the wake of South Pacific cyclones could help predict the impact of warming ocean temperatures, New Zealand researchers believe.

Dr. Pete Russell, of the University of Otago’s Department of Marine Science, and Dr. Christopher Horvat, of the University of Auckland’s Department of Physics, have published a study on the oceanic biological effect of Cyclone Oma which passed near Vanuatu in 2019.

“While Oma was a relatively benign , it produced a massive phytoplankton  in its wake—the single most abnormal event in the history of South Pacific chlorophyll measurements,” Dr. Russell says.

“Such an extreme event can produce a large amount of biomass in a part of the  that is typically a biological desert. We don’t yet know about the fate of this biomass, but one possibility is that it could end up on the bottom of the ocean, sequestering carbon.”

Read the full article at phys.org

Scientists get peek into how some fish change sex as adults

July 10, 2019 — If in the beginning there was male and female, fish seem to have forgotten the memo.

For nearly 500 fish species, including the clownfish in “Finding Nemo,” the great divide between sexes is more like a murky line: If circumstances call for it, the fish can swap their sex, with females turning into males in some species and males turning into females in others.

People think of sex as being fixed, said biologist Erica Todd from the University of Otago in New Zealand, “but there are so many fish that can push it in the other direction.”

Scientists have known for decades about the sex trades, but they’ve had limited understanding of how the exchange happens. In a study published Wednesday in Science Advances, Todd and her colleagues detail the molecular events behind this ability, as well as what keeps mammals stuck as one sex or another.

The researchers looked at the bluehead wrasse, a reef fish that swims in small groups of a dominant blue-headed male and a posse of smaller yellow females. Normally the male and females stay as they are, feeding together and occasionally mating. But if a predator happens to snatch up the lead male, the dominant female in the group will become a male.

“The sex change in this species is remarkable because it’s so quick,” Todd said. It takes only minutes to a few hours for the female’s behavior to become more territorial and aggressive like a male. In a few days, she courts other females. And after eight to 10 days, she’s fully transitioned to a male.

Read the full story from the Associated Press at The Washington Post