Ocean Dead Zones are Spreading, and That Spells Disaster For Fish

London, 7 Apr (Prensa Latina)Falling ocean oxygen levels due to rising temperatures and influence from human activities such as agrochemical use is an increasingly widespread problem.
Considering that the sea floors have taken more than 1,000 years to recover from past eras of low oxygen, according to a recent University of California study, this is a serious problem.

Ocean regions with low oxygen levels have a huge impact on aquatic organisms and can even destroy entire ecosystems. Areas of extremely low oxygen, known as oxygen minimum zones or “dead zones”, are estimated to constitute 10 percent and rising of the worldâ?Ös ocean.

This expansion has been attributed to a warming climate, which increases water temperature, changes ocean circulation, and decreases the solubility of oxygen in sea water.

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Extremely bad heavily-political “spin” put on a good scientific paper. This has nothing whatever to do with “ocean dead zones”, which are not spreading, anyway.

The paper studied fossils “during the transition from the last ice age to the more-recent interglacial period” and found that there was a period of sudden reduction over a timespan of 130 years. I would hazard a guess that this small extinction event was associated with undersea volcanic action. We already know that volcanic action along the mid-Atlantic ridge has wiped out almost all marine invertebrates there (note that the famous tube-worms are not found here). Further, I’ve calculated that the frequency of major volcanic eruptions along mid-ocean ridges is consistent with one having occurred at about the date observed.

mollwollfumble said:

Extremely bad heavily-political “spin” put on a good scientific paper. This has nothing whatever to do with “ocean dead zones”, which are not spreading, anyway.

The paper studied fossils “during the transition from the last ice age to the more-recent interglacial period” and found that there was a period of sudden reduction over a timespan of 130 years. I would hazard a guess that this small extinction event was associated with undersea volcanic action. We already know that volcanic action along the mid-Atlantic ridge has wiped out almost all marine invertebrates there (note that the famous tube-worms are not found here). Further, I’ve calculated that the frequency of major volcanic eruptions along mid-ocean ridges is consistent with one having occurred at about the date observed.

“Dead zones are hypoxic (low-oxygen) areas in the world’s oceans and large lakes, caused by “excessive nutrient pollution from human activities coupled with other factors that deplete the oxygen required to support most marine life in bottom and near-bottom water. (NOAA).” In the 1970s oceanographers began noting increased instances of dead zones. These occur near inhabited coastlines, where aquatic life is most concentrated. (The vast middle portions of the oceans, which naturally have little life, are not considered “dead zones”.)”

http://en.wikipedia.org/wiki/Dead_zone_(ecology)

Exactly. Prior to pollution-control laws.

mollwollfumble said:

Exactly. Prior to pollution-control laws.

>>Mass extinctions are nearly always followed by a period of tens of thousands of years when no new species emerge, a ‘dead zone’. The dead zone following the Early Triassic period is such an extreme outlier, at five million years long, that researchers have long suspected that there must be some unknown influence at work.

The new research clarifies: “the cause of this lengthy devastation was a temperature rise to lethal levels in the tropics: around 50-60°C on land, and 40°C at the sea-surface.”

Lead author Yadong Sun, who is based in Leeds while completing a joint PhD in geology, says: “Global warming has long been linked to the end-Permian mass extinction, but this study is the first to show extreme temperatures kept life from re-starting in Equatorial latitudes for millions of years.”<<

http://scienceheathen.com/2012/10/19/5-million-year-long-dead-zone-caused-by-extreme-heat-followed-largest-extinction-event-ever-250-million-years-ago/

> the end-Permian mass extinction …

… is volcanic. The timing matches that of the flood basalt event known as the Siberian Traps. I personally think it was the sulphur dioxide they emitted that killed off everything that breathed oxygen. It may have been some other change to the atmosphere, but the sulphur dioxide hypothesis neatly explains the worldwide extinction of the ammonites. All major extinctions are time-matched to major volcanic events, even the K-T.

mollwollfumble said:

> the end-Permian mass extinction …

… is volcanic. The timing matches that of the flood basalt event known as the Siberian Traps. I personally think it was the sulphur dioxide they emitted that killed off everything that breathed oxygen. It may have been some other change to the atmosphere, but the sulphur dioxide hypothesis neatly explains the worldwide extinction of the ammonites. All major extinctions are time-matched to major volcanic events, even the K-T.

Volcanos can react in two ways; they can belch out magma and dust particles that rise to the upper atmosphere, blocking out the Sun’s rays to cause a Nuclear Winter. Alternatively they can emit vast quantities of CO2 with few fine particles and this will create the greenhouse effect with a rapid rise of temperature, which is certainly a contributing facture for global warming.

>>In the distant past (prior to about 10,000 years ago), CO2 levels tended to track the glacial cycles. During warm ‘interglacial’ periods, CO2 levels have been higher. During cool ‘glacial’ periods, CO2 levels have been lower. This is because the heating or cooling of Earth’s surface can cause changes in greenhouse gas concentrations. <<

http://www.epa.gov/climatechange/science/causes.html