Decline in global oceanic oxygen content during the past five decades

http://www.themillbrookindependent.com/content/sos-sucking-oxygen-out-sea
SOS: SUCKING OXYGEN OUT OF THE SEA
by Bill Schlesinger
Tue Mar 21st, 2017
This report is based on this paper -
Decline in global oceanic oxygen content during the past five decades
http://www.nature.com/nature/journal/v542/n7641/abs/nature21399.html

Schmidtko, S., L. Stramma, and M. Visbeck. 2017.   
Nature 542: 335-339.

http://www.bizjournals.com/baltimore/news/2013/10/14/40000-oysters-grow-in-baltimore-harbor.html?page=all

Nearly 40,000 oysters to grow in Baltimore's Inner Harbor

The Inner Harbor waters will soon be home to 37,500 new residents — baby oysters.

The Waterfront Partnership of Baltimore is teaming up with the Chesapeake Bay Foundation to plant five oyster gardens around the Inner Harbor on Tuesday. It’s another step in the Healthy Harbor initiative, the Waterfront Partnership’s mission to make Baltimore’s harbor swimmable and fishable by 2020.

“If we had a clean Chesapeake Bay we wouldn’t have to do any of this stuff,” saidAdam Lindquist, the Healthy Harbor coordinator for the Waterfront Partnership.

The gardens will be located at five points around the Inner Harbor: near the Rusty Scupper restaurant; near the Lightship “Chesapeake,” between Piers III and IV; between Piers IV and V; and in Fells Point.

The 75 oyster cages in the gardens will each hold 500 baby oysters, which will help clean the water as they mature over the next nine months. After they reach adulthood in June 2014, the oysters will be transported to the Fort Carroll Oyster Sanctuary.

The project costs about $15,000 per year for the materials and use of the Snow Goose, the Chesapeake Bay Foundation’s boat used to transport the oysters. The cost doesn’t include volunteer hours to maintain the gardens, Lindquist said. A grant from the Abell Foundation will help fund the initiative.

About 12 volunteers each from Brown Advisory, Legg Mason, BGE/Constellation Energy and T. Rowe Price, as well as students from Digital Harbor High School and the Green School of Baltimore, will be responsible for maintaining the oyster cages. That requires pulling them to the surface once a month to scrub off any barnacles, mussels or microorganisms.

If the program is successful, Lindquist said he hopes to repeat it next year with new oysters.

Oysters are filter feeders, meaning they clean the water as they feed on the algae that suffocates aquatic life. The Chesapeake Bay once had enough oysters to filter the entire volume of the bay in three days; today’s oyster population is only 1 percent of historical levels.

But oysters alone can’t clean the Inner Harbor. Stormwater runoff polluted with excess nutrients is the root cause of the harbor’s algae blooms, so Lindquist said the Waterfront Partnership will continue to focus on other measures outside the oyster program to get the harbor to a swimmable, fishable state.

“Oysters are not the only solution,” Lindquist said. “It’s just one more thing we can do to help restore the ecosystem, but really the harbor is just a reflection of the health of our neighborhoods.

http://au.news.yahoo.com/thewest/a/-/newshome/15001651/gloom-over-anaemic-rivers/

Gloom over 'anaemic' rivers

Authorities have all but abandoned improving the health of big areas of the Swan and Canning rivers in the short term, according to a report that shows the system's condition is anaemic.

The Swan River Trust's annual report painted a bleak picture of the waterway after a year in which it was hit with mass fish kills and several toxic algal blooms.

According to the trust's own monitoring, nitrogen levels were too high at almost half of its stations for the fourth year in a row, while phosphorous levels exceeded benchmarks at 20 per cent of sites.

The report showed the amount of chlorophyll-a - a green pigment that indicates algal growth - was far too high everywhere and had been getting worse since 2008.

And dissolved oxygen levels, which were propped up by oxygen plants as a "last line of defence", were too low in each river area except its lower reaches, which were most affected by seawater.

Crucially, the trust said conditions were not expected to improve in many areas and according to several criteria "in the foreseeable future".

This was because of the system's high embedded nutrient level and Perth's lack of winter rain, which reduced the rivers' ability to flush themselves out.

The trust reported six sewage discharges into the rivers last year, 11 industrial discharges and 22 oil slicks or spills.

A spokeswoman for Environment Minister Bill Marmion said the trust had failed to meet its own benchmarks.

"The trust and its partners deliver many positive initiatives that improve water quality and environmental condition in priority catchment areas," she said.

Greens MP Alison Xamon said the trust's report revealed a grim picture of the health of the rivers and legislative action was urgently needed to clean the system.

Shadow environment minister Sally Talbot said the rivers would not recover until water-soluble fertilisers were banned in the catchment."

Comment

Ms Talbot has missed the point, all fertilizers HAVE to be water soluble. 

All living organisms (bacteria to humans) are about 70% water and can only consume water soluble material. Therefore fertilizer, food and sewage is always water soluble. 

The headline hits the mark, perhaps unintentionally. 
The problem with polluted rivers and lakes is lack of IRON and not excess nutrients. 

Nualgi provides iron on a silica base. 

Goby fish in Hypoxic water

http://www.newscientist.com/article/dn19182-super-goby-helps-salvage-ocean-dead-zone.html

Super goby helps salvage ocean dead zone

• 19:00 15 July 2010 by Michael Marshall

A resilient fish is thriving in an inhospitable, jellyfish-infested region off Africa's south-west coast. And crucially it is helping to keep the local ecosystem going, and to preserve an important fishery.

The Benguela ecosystem lies off the coast of Namibia. It exists in waters only 120 metres deep that used to be a rich sardine fishery, but in the 1960s the sardine population crashed because of overfishing and environmental factors, and the region was invaded by algal blooms and swarms of jellyfish.

The algae have used up almost all the oxygen in the water, leaving the bottom half with oxygen levels below 10 per cent, far too little for most sea creatures. At about 80 per cent, levels are almost normal in the upper waters – but those regions are thick with jellyfish and algae, and therefore unwelcoming to most other life.

What's more, when the algae die they sink to the bottom and decay, releasing large quantities of the poisonous gas hydrogen sulphide. Nevertheless, local fish called bearded gobies have flourished in Benguela. Until now, nobody has understood how they survive it.

Tough fish

Anne Utne-Palm of the University of Bergen, Norway, and colleagues surveyed Benguela's gobies. Using acoustic tracking, they found that bearded gobies spend the daylight hours at the very bottom – the only backboned animals in the area to do so. Their stomach contents reveal that they feed off dead algae fallen from the surface, and also on the jellyfish.

The team found that the gobies could survive for hours in the oxygen-poor waters. They lower their metabolic rate to do so – but despite this they remain alert and can flee predators, as tank tests revealed.

At night the gobies head up to the surface to take in oxygen. They often hide themselves in the jellyfish clouds, where predators rarely venture.

Despite this, the gobies still fall victim to predators such as horse mackereland hake. This means that they act as a recycling system, ferrying nutrients that might otherwise be lost on the seabed back up to the surface.

"It's a lucky thing that the ecosystem had this goby," says Utne-Palm. "They bring lost resources back into the food chain."

Fish food

Daniel Jones of the National Oceanography Centre in Southampton, UK, says that low-oxygen zones like Benguela are becoming more common as a result of human activities.

"It's good to see that some ecosystems can be sustained throughout this sort of hypoxic event," he says, "but I suspect that in a lot of environments there isn't a 'super-goby' around to help out."

The sardines may have gone, but horse mackerel and hake survive in the area by feeding on the gobies, and are regularly fished by humans. "If it weren't for the gobies, the human fishery would be in a worse condition than it is," says Jones.

Journal reference: Science, DOI: 10.1126/science.1190708

SOS: Is Climate Change Suffocating Our Seas?

http://www.redorbit.com/news/science/1767833/sos_is_climate_change_suffocating_our_seas/

SOS: Is Climate Change Suffocating Our Seas?

Posted on: Saturday, 10 October 2009, 08:36 CDT

Scientists work to explain why massive "dead zones" have been invading the Pacific Northwest's near-shore waters since 2002

Yet another ecological scourge may earn a place on the ever-lengthening list of problems potentially caused by climate change: the formation of some so-called "dead zones"—huge expanses of ocean that lose virtually all of their marine life at depth during the summer.

Possible connections between climate change and the relatively recent formation of dead zones in the Pacific Northwest's coastal waters are currently being studied by a research team that is funded by the National Science Foundation and co-led by Jack Barth of Oregon State University (OSU) and Francis Chan of OSU. (Jane Lubchenco, who is currently on leave from OSU while serving as the Administrator of the National Oceanic and Atmospheric Administration, also previously co-led the team.)

WORLDWIDE DEAD ZONES

The Earth currently has more than 400 oceanic dead zones, with the count doubling every decade. A single dead zone may cover tens of thousands of square miles.

Dead zones form where microscopic plants, known as phytoplankton, are fertilized by excess nutrients, such as fertilizers and sewage, that are generated by human activities and dumped into the ocean by rivers, or more rarely, where they are fertilized by naturally occurring nutrients. The result: blooms of organic matter that ultimately decompose through processes that rob the ocean of life-sustaining oxygen. Animals that fail to flee dead zones either suffocate or suffer severe stress.

--------------------------
The reference to Phytoplankton is not entirely correct - Cyanobacteria and Dinoflagalletes may lead to fall in DO level, but Diatom Algae leads to increase in DO level. They do not die and decompose, they are consumed by zooplankton or fall to the ocean floor.

This distinction is not being made by most people.
The solution is to get the right type of Phytoplankton to bloom - Diatom Algae.

Pacific Ocean 'dead zone' in Northwest may be irreversible

http://www.latimes.com/news/nationworld/nation/la-na-oregon-ocean9-2009oct09,0,4615320.story

Pacific Ocean 'dead zone' in Northwest may be irreversible
Oxygen depletion that is killing sea life off Oregon and Washington is probably caused by evolving wind conditions from climate change, rather than pollution, one oceanographer warns.

By Kim Murphy
October 9, 2009

Reporting from Corvallis, Ore. - An oxygen-depleted "dead zone" the size of New Jersey is starving sea life off the coast of Oregon and Washington and will probably appear there each summer as a result of climate change, an Oregon State University researcher said Thursday.

The huge area is one of 400 dead zones around the world, most of them caused by fertilizer and sewage dumped into the oceans in river runoff.

But the dead zone off the Northwest is one of the few in the world -- and possibly the only one in North America -- that could be impossible to reverse. That is because evolving wind conditions likely brought on by a changing climate, rather than pollution, are responsible, said Jack Barth, professor of physical oceanography at OSU.

"I really think we're in a new pattern, a new rhythm, offshore now. And I would expect [the low-oxygen zone] to show up every year now," Barth said at a news conference.

Thursday's briefing coincided with the release of a National Science Foundation multimedia report that said the number of dead zones worldwide was doubling every decade.

In the Pacific Northwest, the report said, the areas of hypoxic, or low-oxygen, water that long have existed far offshore began to appear closer to land in 2002, a phenomenon that may mean they are even deadlier to sea life that exists near the ocean floor.

Low-oxygen zones are created when large blooms of plankton form on the surface of the ocean, then decay and fall to the sea floor, where further decay eats up the oxygen in the water.

"When oxygen gets too low in the ocean, it has a deleterious effect on organisms," Barth said. "They either have to flee the area, or they get stressed or even die off. Those die-off [areas] are dead zones."

The affected waters of the continental shelf in Oregon and Washington for the most part are not inundated with polluted river runoff; the nutrients that feed the plankton blooms here come from natural sources, Barth said. And researchers believe a change in the flushing movement of water along the coastline may be responsible.

The gradual warming of surface waters across the north Pacific, the report funded by the National Science Foundation said, has tended to isolate deep waters far below the surface -- allowing less oxygen penetration.

There also has been a change in wind patterns, encouraging the upwelling of that low-oxygen water and inhibiting the natural flushing action of water.

"What we're seeing is changes in the oxygen content of the water and the winds that drive the ocean and cause that flushing," Barth said, calling it a "double whammy."

Although it is possible that the phenomenon could be related to cyclical ocean currents and temperatures, Barth said that he was more inclined to believe it was a long-term result of climate change. He said that researchers had scanned records going back to the 1950s and had seen nothing similar to what has appeared every year off the Oregon coast since 2002.

The worst year on record was 2006, when the Pacific Northwest zone saw an area of "anoxia," or virtually no oxygen at all.

kim.murphy@latimes.com