Australia - The Cells from Hell - Pfiesteria piscicida

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http://www.abc.net.au/science/slab/cells/default.htm

 

 

 

The " Cells from Hell " - Pfiesteria piscicida - and other toxic

dinoflagellates are moving south. Taylor Bildstein asks if we can

control them?

 

With the aid of intensive animal farm effluent, Pfiesteria outbreaks

in the United States have caused frightening health effects and damage

to local fishing industries. About US$40 million was lost from the

Chesapeake Bay fishing industry in 1997.

 

Researcher Dr. Joann Burkholder and her team at North Carolina (NC)

State University have reported that the toxins from these " Cells from

Hell " can affect people as well as fish. She claims that the toxins

inflict skin rashes, memory loss for up to six months and confusion to

the extent that an intelligent adult can't calculate the answer to a

question like 1+2=3.

 

These " Cells from Hell " are slowly invading southern waters, possibly

in the discharged ballast waters of ships.

 

 

New quarantine laws were introduced on the 1st of July to control the

importation of these types of marine pests into Australian ports

through ballast water discharges. The " Cells from Hell, " are toxic

dinoflagellates, the smallest of the ballast-transported marine

invaders. They have a complicated life cycle that increases their

chance of surviving a journey in ballast waters so this makes them

good indicators for Australia's new quarantine laws: if we can

eradicate toxic dinoflagellates from ballast water we have probably

killed all of the other stowaways as well.

Pfiesteria close up

Pfiesteria as seen through a Scanning Electron Microscope.

 

Most of Australia's ports aren't regularly surveyed for introduced

marine organisms, partly because it's an expensive procedure, and

partly because we face shipping exclusion by relatively marine

pest-free countries if we find out that our ports are rife with pests.

This type of embargo would damage our local and national economy.

 

Because of our reluctance to quantify the presence of toxic marine

organisms in our own ports, we really don't know whether the toxic

dinoflagellates that caused so much harm in the United States are

already here or not.

 

With so much at stake, should Australia be questioning the

effectiveness of our new quarantine laws and asking what we can do to

avoid fish kills, aquaculture revenue losses, paralytic shellfish

poisoning and losses in biodiversity that can be caused by the

introduction of foreign toxic dinoflagellates? Should we be paying

more attention to the environmental conditions that could provoke

existing species?

 

What are toxic dinoflagellates?

Pfiesteria

Pfisteria is a toxic dinoflagellate with the potential to kill massive

numbers of estuarine fish.

 

Dinoflagellates are microscopic, plant-like organisms that are found

in all marine and fresh-water environments. A number of them can

produce very potent toxins that possibly evolved as a chemical warfare

agent to kill off other microscopic species so the cells can dominate

their ecosystems.

 

Toxic dinoflagellates don't only threaten marine ecosystems, they are

also a direct threat to people who eat shellfish contaminated with

toxins from some species. Paralytic shellfish poisoning (PSP) kills

15% of the people who suffer the illness. It originated in North

America but since ballast waters have moved marine species from

port-to-port, PSP has been found throughout the world.

 

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The 'Cell from Hell' is a toxic dinoflagellate

 

Pfiesteria piscicida doesn't cause PSP, but is a toxic dinoflagellate

that has the potential to kill massive numbers of estuarine fish and

poison a person's mind under the right conditions. This is when

Pfiesteria, normally a docile browser, turns into the " Cells from

Hell, " eating fish flesh and poisoning fishermen.

1996 Tuna kill

After Chesapeake Bay, USA was poisoned Australia's Port Lincoln

fish-farmers also faced losses costing millions.

 

The most famous example of this transformation was in 1997 when a

spill of chicken waste in a quiet United States fishing village

changed the chemical composition of the Chesapeake Bay estuary and

gave Pfiesteria an advantage over other living things in the bay.

They quickly dominated their ecosystem, killing and washing ashore

more than 300,000 fish that year, many of which advertised open sores

on their bodies. It was this episode that cost the Chesapeake seafood

industry more than $USD 40 million ($AUD 79.6 million).

 

Pfiesteria piscicida and a second species, Pfiesteria shumwayae, have

been implicated as the primary causative agents of well over a billion

fish deaths in North Carolina (NC) estuaries by the local Centre for

Applied Aquatic Ecology (CAAE). The first big fish kill happened in

the Neuse Estuary in 1991, where a billion fish died. Dr. Burkholder

says that ever since that initial kill, NC estuaries have generally

lost hundreds of thousands to millions of fish per year in toxic

Pfiesteria outbreaks.

 

How do the 'Cells from Hell' affect people?

 

Fishermen in NC have not only been affected economically, they have

also been physically affected by the toxins. Victims have lost their

memories, forgotten where they are, or even who they are.

Fisherman at risk

High toxin levels place fishermen at risk.

 

When human flesh comes in contact with water infested by the Cells,

blisters and abscyses can form on the exposed skin as well as on the

chest and face. According to researchers at the NC State University,

other symptoms of Pfiesteria piscicida exposure are a " drugged "

effect; red eyes, severe headaches, blurred vision, nausea/vomiting,

asthma-like difficulty breathing, kidney and liver dysfunction, acute

short-term memory loss, and serious difficulty being able to read,

remember one's own name, dial a telephone number, or do simple arithmetic.

 

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A unique feature of the transformation is the Cells' unusual ability

to produce toxins that can aerosolise. In this free-moving form, the

toxins can be inhaled to affect more people and animals than they

could if they remained only in water.

 

State and Federal officials in NC, USA were so frightened by the 1997

outbreak and fishing industry losses that all further work with

Pfiesteria piscicida must now be conducted in biohazard level III

containment systems in a limited-access facility.

 

Researchers from CAAE have attempted to isolate the toxins that the

cells produce, but so far they have had no success. Without

verification of the toxin it is difficult for researchers to

understand the outbreaks and difficult to draft appropriate

legislation to control the effects of the toxin.

 

Ballast water transports toxic dinoflagellates like the cells from

hell from port to port, all around the world.

A potentially polluted ship

Ships polluted ballast water provide safe carriage for Pfiesteria.

 

Associate Professor Gustaaf Hallegraeff, of the University of Tasmania

has been studying dinoflagellates since the 1980's and says that

without appropriate safe-guards, which are in the process of being

introduced, toxic dinoflagellates are easily transported into

Australian ports. He recalls: " we picked up some ships coming into

Eden that had 300 million toxic dinoflagellate cysts in their ballast

water and we established a whole culture collection of Japanese and

Korean dinoflagellates from that source. " Thankfully, Pfiesteria

piscicida weren't included in that collection.

 

The " Cells from Hell " still remain undetected in foreign ballast

water, but according to Hallegraeff, the Cells are actually an

indigenous and cosmopolitan species, a common inhabitant of estuaries

all over the world. He says that Pfiesteria piscicida is normally

completely harmless and becomes harmful only when triggered.

Obviously, if the Cells are indigenous to Australia, they aren't

producing the same frightening effects as has been seen in NC.

 

Pfiesteria piscicida was discovered in New Zealand in December 2000 by

Joann Burkholder's team at the CAAE and any studies of the cells in

Australia haven't been published yet. So very little quantified

information is available about their behaviour in southern waters.

One explanation as to why Australia hasn't seen a flare of fish deaths

and human health problems like those in NC is that Australia has

strict effluent control policies.

 

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New Australian Ballast Water Arrangements

 

Our good effluent discharge record may have protected us from

Chesapeake Bay's woes until now, but this doesn't mean that we should

allow indescriminate ballast water discharges in our ports. Other

toxic dinoflagellates can still be imported this way and even if the

" Cells from Hell " are an indigenous species, foreign cells of the

species can have different characteristics to the local cells. With

all of this in mind, efforts have been made to stop any further marine

contamination of any kind.

School of Tuna

Continuing efforts are being made to protect these fish from

contamination.

 

From the 1st July this year, new ballast water arrangements have come

into force for all international vessels visiting Australia.

Permission must now be granted in writing from a quarantine officer

before ballast waters can be discharged in Australian ports or waters.

To help the quarantine officers assess which ships are a larger risk,

a decision support system has been introduced, available to ships from

the world wide web. Alternately, the vessels can discharge their

ballast waters at sea or use an on-board treatment system.

 

However, discharging at sea (a mid-ocean exchange) is only 95%

efficient, it simply dilutes the concentration of cysts and live

stowaways. If a ship contains 300 million cysts and 95% are dumped in

the mid-ocean, about 15 million cysts will remain, while only one cyst

needs to be dumped in a local port for that creature to begin an invasion.

 

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But Hallegraeff is not impressed: " Everything we have to date is still

insufficient to curb this problem, " he says. He suggests that an

international database including all active ports and all

transportable marine organisms be established. This should be

accompanied by the enforcible sterilisation of all ballast waters

using a cheap method that is 100% effective. Current alternatives to

mid-ocean exchanges include heat-treatment, which requires a modified

ship; and chemical treatment, which can cost up to $1 million per dose.

Chattonella

Chattonella, one of the toxic algae Australia is attempting to quarantine.

 

Heat-treatment looks like the most promising option. This is most

likely to be pushed forward by ship-design companies who will profit

when all international vessels are required to have heat-capable

designs, according to international laws which have not yet been

finalised.

 

Hallegraeff estimates that it will be ten years before we have a

comprehensive solution at an international level and until then, we

will have to make-do with the Australian Quarantine Inspection

Service's risk-minimisation strategy.

 

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References

 

Hallegraeff, Gustaaf M. (1998). Transport of toxic dinoflagellates

via ships' ballast water: bioeconomic risk assessment and efficacy of

possible ballast water management strategies. Marine Ecology Progress

Series. Vol. 168: 297-309.

 

ABC Science Online News in Science Report, Cells From Hell Hit

Southern Waters, 23 February, 2001.

 

Links

 

Shape-shifting microbe found in Australia - News in Science,

Wednesday, 22 August, 2001.

 

In a world exclusive Quantum reveals that a second toxic species

of Pfiesteria has been discovered in other parts of the globe

including the coastal waters of Scandinavia and New Zealand.

 

In ABC Science Online's Slab article, Invasion of the Killer

Seastars, Louise Goggin investigates Australia's most serious marine

invader - the Northern Pacific Seastar.

 

Cells From Hell Hit Southern Waters, an ABC News in Science report

exploring the deadly migration of devastating marine algae, Pfiesteria.

 

The Centre for Applied Aquatic Ecology at the North Carolina State

University, USA offers the latest publications on the pharmacological

effects of Pfiesteria toxins.

 

The United States Environmental Protection Agency's Pfiesteria

piscicida homepage provides all the information you should know about

Pfiesteria piscida.

 

Fish Health in the Chesapeake Bay: About Pfiesteria includes

information about algae and human health. It defines what Pfiesteria

are and offers ways of identifying them.

 

Earlier Stories

 

© 2001 Australian Broadcasting Corporation