© Jennifer Reynolds/The Galveston County Daily News via AP, File
FILE - In this Tuesday, Oct. 30, 2012, file photo, Kim Bertini looks over some of the 15,000 dead fish that washed up near her backyard on Lake Madeline in Galveston, Texas. Bertini said she and her husband, Chris, noticed dying fish on a Saturday and woke up the following morning to the dead, floating fish. The Galveston County Daily News reported that experts blame low levels of dissolved oxygen for the fish kill in Lake Madeline. Oxygen levels have dropped in hundreds of lakes in the United States and Europe over the last 40 years, a new study has found.
FILE - In this Tuesday, Oct. 30, 2012, file photo, Kim Bertini looks over some of the 15,000 dead fish that washed up near her backyard on Lake Madeline in Galveston, Texas. Bertini said she and her husband, Chris, noticed dying fish on a Saturday and woke up the following morning to the dead, floating fish. The Galveston County Daily News reported that experts blame low levels of dissolved oxygen for the fish kill in Lake Madeline. Oxygen levels have dropped in hundreds of lakes in the United States and Europe over the last 40 years, a new study has found.
And the authors said declining oxygen could lead to increased fish kills, algal blooms and methane emissions.
Researchers examined the temperature and dissolved oxygen — the amount of oxygen in the water — in nearly 400 lakes and found that declines were widespread. Their study, published Wednesday in the journal Nature, found dissolved oxygen fell 5.5 % in surface waters of these lakes and 18.6% in deep waters.
Comment: Overall, our planet is cooling; and so it begs the question: if warming is involved, is the source of heat geothermal? As is the case in Antarctica? It's also notable that during previous periods of climatological and geologic upheaval - as is undoubtedly afoot during our own era - ocean anoxia has been identified as one factor involved in mass extinction events: