Fish growth and development were positively related to temperature, but survival to settlement was not directly related to ocean conditions
The impact of warming oceans due to climate crises on populations of marine species is of major concern, with risks of irreversible loss of marine and coastal ecosystems. However, the effect of warming is complicated — new research has found black rockfish larvae fared better during two recent years of unusually high ocean temperatures than had been feared.
Scientists from Oregon State University looked into how larval fish growth and mortality will change in warmer conditions as the climate crisis leads to marine heat waves. Fish growth and development were positively related to temperature, but survival to settlement was not directly related to ocean conditions, the study found.
The findings were published in journal Nature’s Scientific Reports.
The research involved analysing juvenile black rockfish (Sebastes melanops) samples collected during a long-term collaboration among Oregon State, the Oregon Department of Fish and Wildlife and the Oregon Coast Aquarium.
The samples were collected nearshore from 2013 to 2019, a time frame that included a marine heat wave between 2014 and 2016.
The dramatic change in water temperature caused by such extreme warm water anomalies increased black rockfish growth in the larval stage, the scientists noted. However, these extreme conditions contributed to reduced survival without sufficient prey or with high predator abundance, the research found.
Rockfish, a diverse genus with many species, are a group of ecologically as well as economically important fishes found from Baja California to British Columbia in North America.
They are known for lifespans that can reach triple digits, an ability to produce prodigious numbers of offspring and variable survival during their early life stages, during which they are highly sensitive to environmental conditions.
“We found that despite fears of doom and gloom with recent anomalous warming of the waters off Oregon’s coast, some young black rockfish grew faster as the temperature increased and, surprisingly, there was both high and low survival during different years of the heat wave,” said Will Fennie, the study’s lead author on the university website.
The oceans are planet Earth’s greatest carbon sink, taking the biggest brunt of human-made global warming. As the excessive heat and energy warm the ocean, the change in temperature leads to unparalleled cascading effects, including ice-melting, sea-level rise, marine heatwaves and ocean acidification.
Today, the ocean has absorbed about 90 per cent of the heat generated by rising emissions. Understanding how future ocean conditions will affect populations of marine species is integral to predicting how climate change will impact both ecosystem function and fisheries management.
“The study is important for gauging the conditions and making management plans that will affect the species’ survival as the ocean experiences increasing variability because of climate change,” Fennie added.
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The research involved analysing juvenile black rockfish (Sebastes melanops) samples collected from 2013 to 2019, a time frame that included a marine heat wave between 2014 and 2016. Photo: iStock.png)
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