From the University of Miami Rosenstiel School of Marine & Atmospheric Science
Ocean acidification as a hearing aid for fish?
Study shows that effects of changing ocean pH may result in increase in the hearing sensitivity of fish
MIAMI – April 18, 2013 – Ocean acidification, which occurs as CO2 is absorbed by the world’s oceans, is known to negatively impact a wide variety of marine animals ranging from massive corals to microscopic plankton. However, there is much less information about how fish may be impacted by acidification, should carbon emissions continue to rise as a result of human activities.
In a new study published in the Proceedings of the National Academy of Sciences USA, University of Miami (UM) Rosenstiel School of Marine & Atmospheric Science researcher Sean Bignami, along with National Oceanic and Atmospheric Administration (NOAA) scientists Ian Enochs, Derek Manzello, and UM Professors Su Sponaugle and Robert Cowen, report stunning new insight into the potential effects of acidification on the sensory function of larval cobia (Rachycentron canandum). Cobia are large tropical fish that are highly mobile as they mature and are popular among recreational anglers.
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VIDEO: In a new study published in the Proceedings of the National Academy of Sciences, University of Miami researcher Sean Bignami, along with NOAA scientists Ian Enochs, Derek Manzello, and UM professors Su Sponaugle and Robert Cowen, report stunning new insight into the potential effects of acidification on the sensory function of larval cobia. The team was the first to utilize 3-D X-rays (micro-CT scans) similar to what a patient might receive at a hospital, to determine that fish raised in low-pH seawater, simulating future conditions, have larger and more dense otoliths (ear stones) than those from higher-pH seawater. Otoliths are distinct calcium carbonate structures within the inner ear of fishes that are used for hearing and balance. The changes resulted in up to a 58 percent increase in otolith mass, and when tested in a mathematical model of otolith function, showed a potential increase in hearing sensitivity and up to a 50 percent increase in hearing range. These findings indicate the potential for significant impact on a key sensory system in fish, with important implications for larval fish recruitment and fisheries replenishment.
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Bignami and the team utilized 3D X-rays (micro-CT scans) similar to what a patient might receive at a hospital to determine that fish raised in low-pH seawater, simulating future conditions, have larger and more dense otoliths (ear stones) than those from higher-pH seawater. Otoliths are distinct calcium carbonate structures within the inner ear of fishes that are used for hearing and balance. The changes resulted in up to a 58-percent increase in otolith mass, and when tested in a mathematical model of otolith function, showed a potential increase in hearing sensitivity and up to a 50-percent increase in hearing range.
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  IMAGE: This is micro-CT imagery of a cobia larva head that has been filtered to view the entire skull (top image) and the more dense otolith (ear stone) structures (bottom image)….
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“Increased hearing sensitivity could improve a fish’s ability to use sound for navigation, predator avoidance, and communication. However, it could also increase their sensitivity to common background noises, which may disrupt the detection of more useful auditory information,” said Bignami, who recently completed his PhD in Marine Biology and Fisheries at UM.
The study, a collaboration between UM and NOAA’s Ocean Acidification Program at the Atlantic Oceanographic and Meteorological Laboratory in Miami, is the first to use micro-CT technology to examine otoliths while still inside the heads of the larval fish.
“This effect of ocean acidification represents a significant change to a key sensory system in fish. Although the ultimate ecological consequences still need to be determined, there is the potential for serious impact on important processes such as larval fish recruitment and fisheries replenishment in this species and perhaps other critical fisheries,” Bignami added.
Article: Bignami S, Enochs I, Manzello D, Sponaugle S, Cowen RK (2013) Ocean acidification alters the otoliths of a pan-tropical fish species with implications for sensory function. Proceedings of the National Academy of Sciences USA. doi:10.1073/pnas.1301365110
Seriously folks, this could be a real problem. If the indicated effects of Ph change affect larger ocean dwelling flesh eating critters, I won’t be able to swim in the ocean again…………….
“hearing sensitivity of fish”
Fish got ears?
Who knew?
I recently had an exchange with a US marine biologist, whom I thought well of until he went all CAGW on me and tried to justify his research conclusions in ocean pH. What astounded me more than anything was his profound ignorance of anything outside of water + CO2 … his arguments and explanations were so weak so to be transparent. Needless to say, this must have been brought on by the insatiable desire for research funding.
Ocean pH is different in each and every location and is different at any time of day.This reliance on modelling over measurements must create acute cognitive dissonance with these people.
Mind you I was more astounded by the golf commentators at the USLPGA event in Hawaii, yesterday, sprouting forth on climate change … blaming it for the windy conditions in the Trade Winds zone.
Of a piece with the observation I’ve seen that more acid waters make the calcium more mobile, and hence more available to living organisms. That would make building larger otoliths easier.