What worries me is the connection
made between Fukushima and this
deadly disease that ALL of the life in our seas face not just our favorite sea star on the west coast. I recently posted an article on the disaster we face with the Pacific sea. Specifically the Great Pacific garbage patch. Is the media giving our oceans the attention they need? Is our government doing what they can to keep our seas free of human contamination? Where will we be without the "Bee" they ask? We will continue to thrive for at least 5 years you say? Well.. where will we be with no oceans you ask? Well we shall see.. we shall see..
PURPLE STAR (Pisaster ochraceus)
Identification:
5 stiff arms with arched disc. Aboral surface very rough, with spiny ridges. Purple, ochre or brown. To 50 cm (20 in) across.
Range:
Prince William Sound, Alaska to Baja California; intertidal to 97 m (320 ft).
Notes:
This is the most conspicuous star in the PNW intertidal. It feeds on mussels, barnacles, snails and limpets. It is well adapted to desiccation, but retreats to damp crevices to avoid exposure when the tide is out. Specimens from sheltered waters are usually purple but those found on exposed coasts are more often ochre or brown. This is believed to be due to the different types of food they eat.
This species is often host to an internal parasite that infests the male gonad and stops sperm production. The parasite was first observed here in 1988 and was previously endemic to the North Atlantic.
The disease tends to progress from no outward signs to behavior changes in which the sea stars
cross their arms and seem to collapse on themselves. Then white lesions
appear on the surface of the sea star's body that turn into holes;
those lesions are typically followed by the disintegration of skin
around the lesion and the loss of a limb or several limbs, and in
extreme cases the animal's entire body is affected by the syndrome. Some
of the creatures physically tear their bodies apart in the process,
scientists say.
"We've seen a
number of cases where all that's left is a puddle of their skeletal
parts and a bunch of bacteria eating away at the tissue," Menge told
Live Science. "It's a pretty gruesome thing to see."
The
current outbreak of sea star wasting syndrome was first reported in
June 2013 along the coast of Washington by researchers from Olympic National Park.
Since that report, die-offs have been documented everywhere from
California to Alaska and even along the East Coast from Maine through
New Jersey.
"Wasting has been
known for a long time, but usually it's very localized to a single site
or single region," Menge said. When that's the case, as it was last
August just north of Vancouver, British Columbia, the chances for
recovery are high since the plankton, or floating forms, of the sea
stars from healthy, nearby populations can recolonize those areas that
were hit.
"The thing that is worrisome now is that it's happening pretty much all along the West Coast, even up into Alaska," Menge said.
The cause of the wasting disease is unknown,
though scientists working on the mystery are testing whether an
underlying virus or bacteria is to blame, along with some environmental
stress, such as water temperature or salt content, making the organisms
more vulnerable to it.
"We
are finding correlations between certain microorganisms and viruses
present in the lesions," Gary Wessel, of Brown University in Rhode
Island, told Live Science in an email. "We are now testing whether these
organisms are causative (by infecting healthy animals and seeing if
they replicate the wasting phenotype) or just associated."
Wessel added that his lab is also looking into the impacts of environmental stressors.
"In
our challenge experiments to test infectivity, we are stressing the
animals with salt conditions and temperature to determine if this
environmental stress makes them more susceptible," Wessel said.
Since sea stars can act as keystone predators, meaning their predatory activities shape an ecosystem,
their loss could have far-reaching impacts, the researchers say. By
eating mussels on the low shores in Oregon, sea stars keep those
populations in check so the bivalves don't explode in numbers, at the
expense of other organisms. Menge said it's too early to say whether the
sea stars' mussel-munching could be compensated by whelks in the area.
In
addition to leaving a void in a finely tuned ecosystem, the loss of sea
stars would also disrupt a seeming iconic shoreline organism.
"The aesthetics of the rocky shore are going to be quite a bit less," Menge said. "They are charismatic beasts."
BIOLOGY
EXTERNAL ANATOMY:
Sea stars are among the most conspicuous of all the invertebrate animals, having a distinctive flattened body basically in the form of a star. Found only in marine environments, these free-living creatures exhibit radial symmetry, generally based on a five-pointed star. Of course there are many exceptions: certain sea stars have six or even more arms. Heliaster kubiniji, found in the Panamic region, may have up to 50 arms, believed to be the most of any sea star.
The body of a sea star is generally flattened and at least somewhat flexible. The internal skeleton is comprised of very numerous separate calcareous pieces bound together by connective tissue and often bearing spines, plates and tubercles. The arrangement and structure of these calcareous plates is the principal diagnostic tool in the identification of a sea star. Although most sea stars appear quite rigid, specialized connective tissue enables them to become surprisingly supple when necessary, especially when attacking prey, fleeing predators or when righting themselves after having been flipped upside down.
Situated on the upper (aboral) side of a sea star are the central anus and the madreporite, a circular calcareous sieve located just off centre. The mouth is located in the centre of the under (oral) side of the body at the centre of open furrows called ambulacral grooves. These structures run the length of each arm and are where the tube-feet are located.
Although sea stars lack developed eyes, they do have "eye spots" complete with a simple lens located at the tip of every arm. These eye-spots are light-sensitive and it has been shown that certain species are drawn toward while others shun light. Spread over the skins of sea stars are neurosensory cells which are highly sensitive to both touch and chemical tastes. These are especially numerous in the suckers of the tube-feet, where they are incredibly dense, up to 70,000 per square millimetre!
With the aid of a magnifying glass, many tiny but exquisite details can be seen on the skin of sea stars. Many species have tiny calcareous pincers called pedicellariae, usually situated in clusters or in wreaths surrounding spines. Variously shaped, pedicellariae may look like forceps, bird beaks, or even bivalve clams. These mini-pincers are extremely effective at deterring predators and keeping the surface free of parasites and fouling organisms. Also scattered over the surface are clusters of tiny finger-like protrusions of the body wall. These thin-walled gills protrude between the skeletal plates, serving to exchange respiratory gases and excrete liquid wastes.
INTERNAL ANATOMY:
Inside the skeleton of a sea star lie the internal organs, including the water vascular system, digestive tract, reproductive organs and nervous system. Controlled by an internal plumbing mechanism called the water vascular system, the tube-feet can be employed in a coordinated fashion, enabling the animals to move about and grasp prey tightly. Open to the sea via the madreporite, the water vascular system uses muscles and hydraulic pressure to operate the tube-feet. When fluid is withdrawn the tip of a tube-foot creates suction, enabling the sea star to cling to a rock, climb a piling or securely grip prey. Individually these suckers are not especially strong, but when used in concert they can apply a surprisingly powerful force. While most species possess tube-feet that terminate in suckers, the sand star, found on soft substrates, has pointed ones. The digestive system occupies much of the space inside a sea star. The mouth opens into two stomachs that are connected to paired lobed organs called pyloric caeca that extend into each arm. These organs secrete digestive juices and also serve for dissolved food storage, becoming swollen when prey is abundant. Wastes are passed out through the anus, located in the centre of the aboral side. Reproductive organs called gonads lie beneath the paired pyloric caeca in each arm. These open into the sea via pores located in the "armpits" of the stars.
Sea stars have no brain or central nervous system. Instead a nerve ring in the central disc connects to radial nerves running down the length of each arm. These nerves join a diffuse network of nerve cells scattered throughout the skin.
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Managing contaminated water
Removing contaminated water from the reactor and turbine buildings had become the main challenge in week 3, along with contaminated water in trenches carrying cabling and pipework. This was both from the tsunami inundation and leakage from reactors. Run-off from the site into the sea was also carrying radionuclides well in excess of allowable levels. By the end of March all storages around the four units – basically the main condenser units and condensate tanks – were largely full of contaminated water pumped from the buildings. Some 1000 storage tanks were set up progressively, including initially 350 steel tanks with rubber seams, each holding 1200 m3. A few of these developed leaks in 2013.Accordingly, with government approval, Tepco over 4-10 April released to the sea about 10,400 cubic metres of slightly contaminated water (0.15 TBq total) in order to free up storage for more highly-contaminated water from unit 2 reactor and turbine buildings which needed to be removed to make safe working conditions. Unit 2 is the main source of contaminated water, though some of it comes from drainage pits. NISA confirmed that there was no significant change in radioactivity levels in the sea as a result of the 0.15 TBq discharge.
Tepco then began transferring highly-radioactive water from the basement of unit 2 turbine hall and cabling trench to the holding tank and waste treatment plant just south of unit 4. The water contained 3 TBq/m3 of I-131 and 13 TBq/m3 of Cs-137. Some 120 m3/day of fresh water was being injected into unit 2 reactor core and this replenished the contaminated water being removed, as in the other units.
Tepco built a new wastewater treatment facility to treat contaminated water. The company used both US proprietary adsorbtion and French conventional technologies in the new 1200 m3/day treatment plant. A supplementary and simpler SARRY plant to remove caesium using Japanese technology and made by Toshiba and Shaw Group was installed and commissioned in August 2011. These plants reduce caesium from about 55 MBq/L to 5.5 kBq/L – about ten times better than designed. Desalination is necessary on account of the seawater earlier used for cooling, and the 1200 m3/day desalination plant produces 480 m3 of clean water while 720 m3 goes to storage. By mid-March 2012, over 250,000 m3 of water had been treated. This, at about 400 m3/d, is then recycled for further cooling in the three reactors, following which it is treated again. A steady increase in volume of the stored water (about 400 m3/d net) is due to groundwater finding its way into parts of the plant and needing removal and treatment. In October 2012 Tepco was reported to be struggling to store over 200,000 m3 of contaminated water, while anticipating the start-up of a new Toshiba water treatment plant, in November, which was to allow discharge of clean water to the sea.
Early in 2013 Tepco started to test and commission this Advanced Liquid Processing System (ALPS), developed by EnergySolutions and Toshiba. Each of three trains is capable of processing 250 m3/day to remove 62 remaining radioisotopes. Initially Tepco planned to run two simultaneously while holding the third in reserve, but then it planned three-stream operation from April 2014 with a view to treating all the water by early 2015.
The ALPS is a chemical system which will remove radionuclides to below legal limits for release. However, because tritium is contained in water molecules, ALPS cannot remove it, which gives rise to questions about the discharge of treated water to the sea. Tritium is a weak beta-emitter which does not bio-accumulate (half-life 12 years), and its concentration has levelled off at about 1 MBq/L in the stored water, with dilution from groundwater balancing further release from the fuel debris.
The clean tritiated water is the focus of attention in 2014. A September 2013 report from the Atomic Energy Society of Japan recommends diluting the ALPS-treated water with seawater and releasing it to the sea at the legal discharge concentration of 0.06 MBq/L, with monitoring to ensure that normal background tritium levels of 10 Bq/L are not exceeded. (WHO drinking water guideline is 0.01 MBq/L tritium) The IAEA is reported to support release of tritiated water to the ocean, as does Dr Dale Klein, chairman of Tepco’s nuclear reform monitoring committee (NRMC) and former chairman of US Nuclear Regulatory Commission. The government has an expert Task Force considering the options.
In September 2013 about 930 tanks with 406,000 m3 of capacity held about 330,000 m3 of water, most of this not yet treated through ALPS. About 300 of the tanks are built from flanged steel panels with rubber seals, and one of these leaked significantly in mid-2013 (see below). Tepco plans to increase the storage capacity for contaminated water at the site to 700,000 m3 by September 2015. A total of about 230,000 m3 of water was recovered from injection into the reactors of units 1 to 3 from March 2011 to late 2013.
By the end of June 2011, Tepco had installed 109 concrete panels to seal the water intakes of units 1-4, preventing contaminated water leaking to the harbour. From mid-June some treatment with zeolite of seawater at 30 m3/hr was being undertaken near the water intakes for units 2 & 3, inside submerged barriers installed in April. From October, a steel water shield wall was built on the sea frontage of units 1-4. It extends about one kilometre, and down to an impermeable layer beneath two permeable strata which potentially leak contaminated groundwater to the sea. The inner harbour area which has some contamination is about 30 ha in area. The government in September 2013 said that “At present, statistically-significant increase of radioactive concentration in the sea outside the port of the TEPCO’s Fukushima Daiichi NPS has not been detected.” And also that “The results of monitoring of sea water in Japan are constantly below the standard of 10 Bq/L” (the WHO standard for Cs-137 in drinking water).
A four-year international survey assessing radiological pollution of the marine environment near the plant commenced in July 2011, under IAEA auspices and led by Australia, South Korea and Indonesia. In September 2011, researchers at the Japan Atomic Energy Agency, Kyoto University and other institutes estimated that about 15 PBq of radioactivity (I-131 and Cs-137) had been released into the sea from late March through April, including substantial airborne fallout. In August 2013 Tepco estimated that 20 to 40 TBq of tritium might have leaked into the sea over 28 months since May 2011, which it compared with 22 TBq/yr discharge limit from the six-unit plant normally. The 9-month estimated releases from December 2012 for Sr-90 and Cs-137 were 0.7 and 1.0 TBq respectively, compared with 0.22 TBq/yr combined discharge limit. This is going into the 30 hectare inner harbour area, which is barricaded from the open sea.
In August 2013 a leak of partly-treated water was discovered and rectified. The water concerned in the puddle on the ground (concentrated by evaporation in hot weather) had 80 MBq/L, and it was initially feared that about 300 m3 (24 TBq) had leaked into the soil immediately adjacent to the tank and some possibly moved further. At least six cubic metres of soil was identified as contaminated, and was removed. Tepco said that it was the most serious event at the plant since the March 2011 accident, and that "There is a possibility that contaminated earth and sand flowed into the drainage. We cannot rule out the possibility that part of the contaminated water flowed into the sea." The NRA classified the incident as a Level 1 ‘Anomaly’ on INES scale, but the following day (22 August) it speculated that it maybe should be Level 3 – a ‘Serious Incident’ comparable with seven well-reported reactor problems in the past 25 years. Tepco shares dropped 16% on the Tokyo stock exchange. The following week (28 August) the NRA confirmed its provisional Level 3 rating, without giving a convincing explanation of why it qualified thus. However, the water in the leaky tank had only 0.2 MBq/L, and the NRA admitted that the leak could have been much smaller than it first said. The maximum credible leakage was thus 60 GBq – less than 1% of a single radioisotope source for medical therapy. The NRA chairman was quoted as saying that the INES ranking might be reviewed again.
Apart from the above-ground water treatment activity, there is now a groundwater bypass to reduce the groundwater level above the reactors by about 1.5 metres, pumping from 12 wells and eventually discharging the uncontaminated water into the sea. This will largely prevent it flowing into the reactor basements and becoming contaminated. In addition, an impermeable wall is being constructed on the sea-side of the reactors, and inside this a frozen soil wall will further block water flow into the reactor buildings.
In October 2013 guidelines for rainwater release from the site allowed Tepco to release water to the sea without specific NRA approval as long as it conformed to activity limits. Tepco has been working to 25 Bq/L caesium and 10 Bq/L strontium-90.
Summary: A large amount of contaminated water had accumulated on site, but with the commissioning of a new treatment plant in June 2011 this was progressively being treated and recycled for reactor cooling. However, the main plant is not performing as well as expected, and a supplementary plant was installed. In 2013 a further, more sophisticated plant was commissioned. The persistence of tritium limits the potential to release treated water to the sea. Some radioactivity has been released to the sea, but this has mostly been low-level and it has not had any major impact beyond the immediate plant structures. Concentrations outside these structures have been below regulatory levels since April 2011.
For further reading I recommend:
Encyclopedia of Life- (Pisaster ochraceus) Ochre Sea Star
Fukushima Fallout - Did you know?
Videos I recommend:
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