Archives par mot-clé : Fishes

The Decline Effect – Part 1: Ocean Acidification

by K. Hansen, Feb 22, 2022 in WUWT

There have been a couple of mentions of the decline effect over the past month, mostly prompted by a recent paper that appeared in  PLOS BIOLOGY  authored by Jeff Clements, Josefin Sundin, Timothy Clark, and Fredrik Jutfelt titled “Meta-analysis reveals an extreme “decline effect” in the impacts of ocean acidification on fish behavior”.

The subject matter of the paper, examining the decline effect in the field of Ocean Acidification (OA), particularly in studies on the effects of OA on fish behavior, is itself interesting.  I have written about OA and OA science many times here at WUWT.

There are two parts to this story about the decline effect.  1)  The specific case of the decline effect in OA studies claimed in the Clements et al. paper.   2)  The general case of the hypothesized causes of the decline effect in the sciences.

This essay will address the first issue:  the decline effect in OA studies.

The decline effect in OA science:

As for the specific OA case,  part of that story, featured in the Clements et al. paper,  has been well-covered by Steve Milloy at JunkScience in his article “Climate fish scare turns out to be just a fish story”.

There are several obvious potential causes of a decline effect in a field. They are: publication bias, citation bias, methodological bias, and investigator effects. 

As part of the review process of the new Clement et al. paper, each of those potential causes was investigated – and all but one were eliminated as a major cause.  It is that last cause that I write about today.

The missing parts in Steve Milloy’s coverage are something that I have written about before and is left under-said Clements et al. (2022):

First, you may recall that Timothy Clark (one of the co-authors of Clements (2022)) and others wrote a paper bluntly titled: “Ocean acidification does not impair the behaviour of coral reef fishes” published Nature in January 2020.

Doomsday Climate Studies Turn Out To Be Overblown Nonsense

by Washington Are Beacon Staff, Feb 17, 2022  in The WashigntonFreeBeacon

For over a decade, scientists have warned that the acidification of ocean water could decimate fish populations. Acidification changed fish behavior, several studies found, making them less likely to evade predators.

As carbon emissions pushed pH levels higher and higher, climate advocates sounded an apocalyptic tone. Fewer fish would mean fewer fisheries, which would imperil the livelihoods of millions of fishermen across the globe. It could also mean fewer medicines, many of which are derived from marine life.


According to a new paper in a top-ranked biology journal, these concerns are vastly overblown.

The paper, published in PLOS Biology on Feb. 3, reviewed 91 studies of the effect of ocean acidification on fish behavior. It found that better-quality studies tended to find smaller effects on fish behavior—and that the studies with the most dramatic results tended to have low sample size, making them less statistically reliable.

Fishy Business: Alleged Fraud over Ocean Acidification Research, Reversal on Coral Extinction

by R. Alexander, June 28, 2021 in ScienceUnderAttack

In the news recently have been two revelations about the sometimes controversial world of coral reef research. The first is fraud allegations against research claiming that ocean acidification from global warming impairs the behavior of coral reef fish. The second is an about-face on inflated estimates for the extinction risk of Pacific Ocean coral species due to climate change.

The alleged fraud involves 22 research papers authored by Philip Munday, a marine ecologist at JCU (James Cook University) in Townsville, Australia and Danielle Dixson, a U.S. biologist who completed her PhD under Munday’s supervision in 2012. The fraud charges were made in August 2020 by three of an international group of mostly biological and environmental scientists, plus the group leader, fish physiologist Timothy Clark of Deakin University in Geelong, Australia. The Clark group says it will publicize the alleged data problems shortly.

The research in question studied the behavior of coral reef fish in slightly acidified seawater, in order to simulate the effect of ocean acidification caused by the absorption of up to 30% of humanity’s CO2 emissions. The additional CO2 has so far lowered the average pH – a measure of acidity – of ocean surface water from about 8.2 to 8.1 since industrialization began in the 18th century.

Munday and Dixson claim that the extra CO2 causes reef fish to be attracted by chemical cues from predators, instead of avoiding them; to become hyperactive and disoriented; and to suffer loss of vision and hearing. But Clark and his fellow scientists, in their own paper published in January 2020, debunk all of these conclusions. Most damningly of all, the researchers find that the reported effects of ocean acidification on the behavior of coral reef fish are not reproducible – the basis for their fraud allegations against the JCU work.