Gymnodinium catenatum que es la anoxia



Gymnodinium catenatum is a dinoflagellate belonging to the phylum

Dinophyta, kingdom protista. Dinoflagellates are unicellular, contain

The pigments cholorpylls a and c, and xanthophylls, contain cellulose

In their cell wall, carry out oxygenic photosynthesis, and thrive in

A marine environment (madigan, 736). Dinoflagellates have a transverse

Flagellum that attaches laterally and a longitudinal flagellum that

Extends lengthwise from the lateral groove (raven, 366). Dinoflagellates

Are very resilient organisms. They are able to form resting cysts when

Low nutrient levels persist. The cysts drift to the ocean floor, where

They can remain viable for years. Cysts can be transported to other

Locations by the current of the ocean or in the hulls of ships.Que es la anoxia when

Nutrient conditions are favorable, the cysts germinate forming free

Swimming cells (raven, 365).

Dinoflagellates are a basic part of the marine food web. Mass occurrences

Of the phytoplankton are termed algal blooms. In most cases, this is

Beneficial to the marine ecosystem because it is an abundant food source.

Mussels, small fish, and even large fish feed upon the dinoflagellates.

However, some of the algal blooms can cause massive fish kills, the

Contamination of mussels, and a disruption of the marine ecosystem.

The harmful algal blooms (HAB) are classified into two divisions: toxin

Producers, which can contaminate seafood and kill fish, and high-biomass

Producers, which can cause anoxia and death of marine life after reaching

que es la anoxia

Dense concentrations (geohab, 7).

Gymnodinium catenatum belongs to the first group of HAB’s. It

Is responsible for the red tides off the coast of africa and california

And is known to cause paralytic shellfish poisoning (PSP). About 100

Cases have resulted in death and thousands of cases causing illness

(fisheries western australia, 2). G.Catenatum produces saxitoxin

As a secondary metabolite. Saxitoxin is a neurotoxin that disables the

Sodium pump (decarvalho, 552). Mussels feed upon dinoflagellates such

As G. Catenatum. The toxin accumulates and concentrates in the

Filter feeders and humans ingest the shellfish (raven, 364).

The symptoms for the PSP include a variety of gastrointestinal and

Neurological symptoms.Que es la anoxia symptoms for a mild case include headache, nausea,

Vomiting, diarrhoea, and a tingling sensation around the lips, gradually

Spreading to the face and neck. However, in an extreme case of PSP,

The symptoms are much more severe. A person may experience muscle paralysis,

Respiratory difficulty, and death may occur 2-24 hours after ingestion.

The only treatment for paralytic shellfish poisoning is the stomach

Pumped and in extreme cases artificial respiration (fisheries western

Australia, 2).

It is difficult to determine if shellfish are contaminated with saxitoxin

Or some other toxin caused by dinoflagellates. Infected mussels cannot

Be identified visually. Some precautions may be taken to prevent PSP.

People should avoid eating shellfish in areas where red tides are known

que es la anoxia

To occur or during times when a red tide is prevalent. About twenty

Species of dinoflagellates have been shown to produce saxitoxin. If

A red tide is present, the chances increase for the mussels to have

Ingested dinoflagellates that produce saxitoxin. Another precaution

Is cooking and discarding cooking fluids afterward. This decreases the

Amount of poison ingested by the consumer. If the shellfish are left

In the preparatory liquid, they can absorb more of the poison. However,

The only true prevention is to avoid eating shellfish totally or to

Have the shellfish tested by the public health department (fisheries

Western australia, 3).

Harmful algal blooms not only pose a threat to human health, but they

que es la anoxia

Also affect humans economically. In japan, HAB’s cause an estimated

Loss of one billion yen per year occurs due to the death of finfish

And shellfish in aquaculture sites. In 1996, several molluscs were removed

From the market because tests revealed toxin levels well above standards

Set by the world health organization. Estimates for the confiscation

Of the molluscs and the hospital treatments of the poisoning cases were

About 50 million in US dollars (geohab, 9). Harmful algal blooms have

Occurred throughout history. However, there is an increase in the frequency

Of the HAB’s. Human activity affects the occurrence of algal blooms.

Sewage and agricultural runoff provide dinoflagellates with the high

Nutrient levels needed for reproduction.Que es la anoxia transportation to different

Locations is provided by the ship’s ballast waters (geohab, 10).

Increased awareness of the toxins produced by the dinoflagellates may

Reduce the number of illnesses related to the consumption of the shellfish.

However, the algal blooms are devastating economically. Due to the increased

Occurrences of HAB’s, scientists are researching preventative methods.

Research for reducing the population in an algal bloom of G. Catenatum

Occured in japan in 1998. A red tide of G. Catenatum in yatsushiro

Sea was dramatically reduced with the growth of polykrikos kofoidii.

The tests showed that more than 50% of P. Kofoidii predated on

The natural population of G. Catenatum. The P. Kofoidii

que es la anoxia

Successfully contributed to the cessation of G. Catenatum (matsuyama,



1) decarvalho, mamede; jacinto, jorge; ramos, natalia; journal of neurology,

Paralytic shellfish poisoning: clinical and electrophysiological observations,

Vol. 245, issue 8, 1998, pp 551- 554..

2) madigan, michael; marinko, john; parker, jack; brock biology of microorganisms,

Prentice hall, NJ, 2000, pp 735-739.

3) matsuyama, yukihiko; miyamoto, masahide; kotani, yuichi: aquatic

Microbial ecology, grazing impacts of the heterotrophic dinoflagellate

Polykrikos kofoidii on a bloom of gymnodinium catenatum,

Vol 17, pp, 91-98, 1999

4) raven, peter; evert, ray; eichhorn, susan; biology of plants sixth

Edition, W.H. Freeman and company worth publishers, 1999, pp364- 366.Que es la anoxia

5) fisheries western australia, marine biotoxins http://www.Wa.Gov.Au/westfish/sf/broc/fhinfo/fhinfo04.Html

6) GEOHAB: global ecology and oceanography of harmful algal blooms,

1998. Http://www.Phys.Ocean.Dal.Ca/~jhurst/SCOR/GEOHAB/GEOHAB.Html


– this report was written by a student participaring in a microbiology

Course at the missouri university of science and technology. The accuracy

Of the contents of this report is not guaranteed and it is recommended

That you seek additional sources of information to verify the contents.