CORVALLIS, Ore. – A modest warming of coastal waters can have a significant impact on juvenile fish assemblages. Especially in a period of just a few years. That’s from a newly published study has found. All raising concern about the potential effects of climate change.
Norway
Such a shift is taking place on the Skagerrak coast of Norway. Especially where more warm-water fish species have begun appearing over the past two decades. All the while many populations of resident cold-water fish species have declined.
Results of the study have just been published in the journal Global Change Biology.
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Potential Impact of Climate Change
Studying the potential impact of climate change on coastal fishes has been difficult, researchers says. That’s because few long-term records adequately address species diversity. But researchers at Norway’s Institute of Marine Research have been busy. Thereby conducting what has to be one of the longest, most consistent surveys of near-shore waters ever undertaken. For it’s a key to understanding climate change effects.
No Fish
Barceló, who worked with Norwegian researchers on their beach seine surveys, said no new species had appeared in the waters of Skagerrak for nearly three decades beginning in the mid-1960s. Within the next 15 years, however, several pelagic, planktivorou species more characteristic of the Mediterranean arrived. That’s for example, European anchovy (Engraulis encrasicolus) and European pilchard (Sardina pilchardus).
Other warm-water species of fish present now were documented. Those once before in the area, such as juvenile horse mackerel (Trachurus trachurus). Especially when the water warmed in the 1930s and ‘40s and then became less prevalent when it cooled. The corkwing wrasse (Symphodus melops) is another fish species that appeared during the earlier warm period. For then they became less prevalent for more than half a century. All before returning during the latest warming.
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Cold Water Fish
Cold-water species that have been caught less frequently in this dataset over the past two decades. For that’s include cod (Gadus morhua), pollack (Pollachius pollachius), and European eel (Anguilla anguilla).
One concern, the researchers say, is that the present warming is not an anomaly, rather a symptom of climate change that may worsen instead of going away. There may be other factors involved in the introduction of new species, noted Lorenzo Ciannelli, an Oregon State marine ecologist and co-author on the study.
What’s the Key?
The key to understanding the assemblage shift in Norway is the extraordinary data set collected by Norwegian researchers. For the past 96 years, they have conducted an extensive coast-wide seine survey. All during the last two weeks of September. That’s using the same style boats, the same locations and nets. Those that were exactly the same size.
Only five survey leaders have coordinated the effort over 96 years. I mean each one having trained with the previous leader for at least 10 years. All on the operation of setting and hauling the beach seine before taking over the project themselves.
Barceló
Barceló, who worked with the Norwegians over two summers, is also analyzing fish surveys off the Oregon coast, investigating the long-term environmental variability and shifting marine fish assemblages.
She and Ciannelli are in OSU’s College of Earth, Ocean, and Atmospheric Sciences.
Norwegian researchers conducting a similar survey some 85 years ago: https://flic.kr/p/D6ezvk
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By Mark Floyd, 541-737-0788, mark.floyd@oregonstate.edu
This story is available online at: http://bit.ly/20EJmV4
