RED TIDES
Name: Stella Angeli
Animal and plant diversity tutorial group: 4
Professor: Dr. R. Gornall
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he water green
Red tides
What is actually what we call "red tides"? For many years scientists have
tried through experiments and researches to clarify the causes of the red tides
phenomenon and decrease their effects on humanity and ecology, however,
without getting clear answers. One of the thousand questions was: How can a
microscopic organism cause so many environmental problems?
The answer to this question will be given only by the analysis of this
organism, which is related to environmental destruction. "Red tides" is a
phenomenon that occurs in sea water, when toxic microscopic algae
proliferate to higher than normal concentration and can discolor the sea water
red, yellow, brown or green as it is shown in the figures (Fish and
Wildlife Research Institute). Red tides have distributed in many areas of the
Figure 2: Red tides discolor the water red
world like Mexico, Texas, Florida, South and North Carolina etc. Scientists, like
to call the organisms that cause red tides, Harmful Algal Blooms because they
harm species of the aquatic life but the actual scientific name of the alga is
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Karenia brevis( Florida Fish and Wildlife Conservation Commission, Fish and
Wildlife Research Institute, 2005).
Nevertheless, there is one unanswered question related to Red tides
phenomenon: What are the main causes of Red tides? This is a hard question
to be answered even for the scientists, who support that the causes are
unclear. However, they have arrived at the conclusion that some specific
factors might have contributed in the phenomenon increase ( Florida Fish and
Wildlife Conservation Commission, Fish and Wildlife Research Institute, 2005).
Those factors are:
 Human activities
 The coastal upwelling because of the movement of certain ocean
currents
 The coastal water pollution
 The systematic increase in sea water temperature
 The iron-rich dust influx of large desert areas
 The El Niño events, which is an ocean-atmosphere phenomenon
Karenia brevis has the ability to increase by creating visible patches near
the water’s surface and as an organism can last three to five months until it is
destroyed. However, the most important thing about this organism is that it
produces strong chemical neurotoxins, called brevetoxins that can harm the
aquatic species. These brevetoxins bind to voltage-gated sodium channels in
nerve cells, as a result normal neurological processes to disrupt and that
causes the illness described as Neurotoxic Shellfish Poisoning. The effect on
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animals is fatal,
Karenia
brevis
isSodium
responsible
the Cells
death of millions of
Figurewhile
3: Brevetoxin
Effects
on the
Channel for
in Nerve
fish, invertebrates such as clams and oysters, marine mammals and birds.
People can be infected by brevetoxin when they consume infected fish or
oysters and they can be in real danger if the concentration of this neurotoxin is
really high in the body because it might cause death. Normally though the
effects on humans are more related to the appearance of specific symptoms
like tingling in lips, tongue and throat, asthmatic symptoms, diarrhea and
vomiting and a bizarre feeling of temperature confusion i.e. hot feels cold and
vice versa (Florida Fish and Wildlife Conservation Commission).
Those symptoms can become really dangerous if they are not treated
properly, thus treatment should be given immediately, when the patient
appears the symptoms. The first thing a patient should do is to wear filter
masks to decrease the asthmatic symptoms. Then specific asthma medications
are advised like: Albuterol, Dipheniramine, Cromolyn, Prednisone, Brevenal,
and bronchodilators as well as the use of antiemetics and the consumption of
intravenous fluids (Professor Lora E Fleming lecture, University of Miami) .
Now we should have a closer look to Karenia brevis as an organism,
examine how it is classified, its main features and its life cycle.
Karenia brevis classification
Kingdom: Alveolata
Phylum: Dinophyta
Class: Dinophyceae
Order: Gymnodinialles
Alveolata shared characteristics
The most notable shared characteristic is the presence of cortical alveoli,
flattened vesicles packed into a continuous layer supporting the membrane,
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typically forming a flexible pellicle. Alveolates have mitochondria with tubular
cristae, and their flagella or cilia have a distinct structure.
Dinophyta shared characteristics
The main shared feature of the phylum of Dinophyta and Karenia brevis is the
apical grooves. They have a spiraling swimming motion in the marine waters,
contain chloroplasts for photosynthesis and have two flagella.
Dinophyceae shared characteristics
Dinophyceae have an oval shape covered with a thecal surface. They have
apical plate, composed of cellulose or some other polysaccharide microfibrils,
formed in thecal vesicle, sulcus and ridges .
Gymnodinialles shared characteristics
Gymnodinialles have a sulcus located in the intermediate region of the
cingulum and apical grooves. They also contain a carotenoid brownish
pigment, called fucoxanthin, used by these organisms to capture energy.
Karenia brevis main features
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Figure 4: Karenia brevis under microscope
Figure 5: Karenia brevis main parts
Figure 6: Schematic drawing of a generalized motile dinoflagellate cell
Karenia brevis is a photosynthetic dinophlagellate with strongly
dorsoventrally flattened squarish cells. The organism has a length of 23-24 μm,
a width of 24-36 μm and a depth of 10-15 μm. The main parts of the organism
are:
 The apical groove at the anterior part of the cell extending on
both the ventral and dorsal sites.
 The cingulum, a furrow encircling the cell in the middle.
 The cingular ridges, which are longitudinal ridges in the cingulum.
 The longitudinal flagellum which is like a rudder and guides the
cell during locomotion.
 The transverse flagellum which pushes the cell to move forward.
 The sulcus which is the longitudinal area on the ventral surface of
the cell that houses the longitudinal flagellum.
 The theca which contains multiple membrane layers with vesicles
 The chloroplasts, organelles where photosynthesis takes place
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Karenia brevis life cycle
Figure 7: Karenia brevis asexual and sexual life cycle
Karenia brevis usually reproduce by asexual process, dividing into two
cells, then into four and so on. Firstly, cysts of the karenia brevis lay on the
ocean floor and might stay in the ground for years, without being disturbed.
Oxygen and other conditions, such as the right temperature and pressure are
essential for the beginning of the germination process. When the temperature
increases, as well as the light absorbsion, the cyst breaks open and a swimming
cell appears to the ocean. After a few days time the cell reproduces by simple
division and as a result hundred of cells will reproduced within weeks, having
the same number of chromosomes in the nucleus.
However, is really important to mention that karenia brevis might have sexual
reproduction and a new life change and that happens only when the organism
cannot have access in available nutrients, thus growth stops and gametes are
formed. During gametogenesis the chromosomes in the nucleous reassume a
typical dinokaryotic appearance, the nuclear envelope appears in all mitotic
stages and the mitotic spindle is extracellular. Spindle microtubules pass
through furrows and tunnels that form in the nucleus at prophase (Dodge
1987). Some microtubules contact the nuclear envelope, lining the tunnels at
points where the chromosomes also contact. The chromosomes usually have
differentiated, dense regions inserted into the envelope. After that, the two
cells (gametes) join together. Syngamy involves equal motile gametes and is
called isogamy. Then, the formed cell develops into a zygote by homothallism,
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which is the gamete fusion in clonal strains. The product of gamete fusion is a
planozygote, which may remain motile for hours or a few days. Eventually a
non-motile thick-walled resting cyst (hypnozygote) is formed. Excystment
occurs after a varying length of time of inactiveness. Meiosis is heralded by a
peculiar churning and rotation of the nucleus, a process called nuclear cyclosis
associated with the pairing of homologous chromosomes .Meiosis may occur
before or after the encystment and is normally accomplished in two successive
divisions. The mobile zygotes follow the long-term encystment (resting cysts).
The inactive cysts fall into the bottom of the ocean until the time is
appropriate for another germination (Mona Hoppenrath and Juan F.
Saltarriaga, 2008).
Many scientists have done research about the life cycle of Karenia brevis
in order to find out if is connected with the main effects of red tides in humans
and animals. Karen Steidinger, a scientist of the Florida Fish and Wildlife
Conservation Commision, also called "the mother of the red tide research" said
about the life cycle of Karenia brevis: "Basically we know it is born at sea. Then
something happens to fertilize it. As it moves forward shore, the dead fish
fertilize it even more. Then it is over". Steidinger wants to prove a theory of
hers that the sexual stages of that life cycle play a fundamental role in the
onset of red tide and if she manages to prove that, then she might be able to
use her results for preventing further deaths of ocean species (Andy Lindstrom,
2007).
When karenia brevis blooms complete their life cycle, they need to be
initiated and transport to other areas. That happens in four stages. Firstly, the
blooms are introduced into an area ( the area in which they are born), then
they need to grow and increase their population. In addition, they have to
maintain and be moved offshore or inshore by wind and sea currents. The final
stage involves the dissipation and termination of that process, while winds and
currents disperse the cells and transfer them in new water masses.
In conclusion, red tide is a serious phenomenon, which is really possible
to influence the animal food chain and harm peoples’ health, thus, many
programmes are developed and try to give their contribution by doing
researches in order to predict and prevent their destructive effects. Peoples’
health as well as life underwater need to be conserved and we hope that
future discoveries will restore the life chain in sea water by the elimination of
these harmful organisms.
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REFERENCES
1. Anderson, D.M. 1995. ECOHAB: the ecology and oceanography of harmful
algal blooms: A national research agenda. Woods Hole Oceanographic
Institute.
2. Hansen et Moestrup, 1989, Karenia brevis (Davis)
3. Lindstrom A. 2007, Florida wildlife: Unraveling the mystery of Karenia brevis.
4. Mona Hoppenrath and Juan F. Saltarriaga, 2008, Dinoflagellates.
5. Roth P. 2005. The microbial community associated with the Florida red tide
dinoflagellate Karenia brevis: algicidal and antagonistic interactions. MS
thesis. The College of Charleston, Charleston, South Carolina.
6. Earth Observatory,NASA Satellites Detect “Glow” of Plankton in Black
Waters,2004
7. Environmental health ,Harmful algal bloom, 2008
8. Fish and Wildlife Research Institute, Red Tides in Florida
9. Journey North, What is red tide?, 2003
10. Laurin Publishing, 'FlowCytobot' Detects Blooms, 2008
11. National Centers for Coastal Ocean Science, Silver Spring,2008, MD., USA
12. National Ocean Service, Harmful Algal Blooms,2007
13. Ocean World ,Red Tides,2004
14. Shifting Baselines Blog, Can Red Tide Make You Sick?,2005
15. Professor Lora’s E Fleming lecture, University of Miami
16. Dr. Barbara’s Kirkpatrick Start Board member lecture
PICTURES
1. Figure in the first page taken from:
http://resources.edb.gov.hk/~s1sci/R_S1Science/sp/en/syllabus/unit5/images/New
%20graphic/redtide0.jpg
2. Figure 1 taken from: www.whoi.edu/redtide/
3. Figure 2 taken from: http://www.whoi.edu/cms/images/5_47876.jpg
4. Figure 3 taken from: Professor Lora’s E Fleming lecture, University of Miami
5. Figure 4 taken from: http://en.wikipedia.org/karenia_brevis
6. Figure 5 taken from: http://www.liv.ac.uk/hab/Data%20sheets/k_brev/fig1.htm
7. Figure 6 taken from:http://tolweb.org/tree/ToLimages/dinogeneralmaxtol1.300a.jpg
8. Figure 7 taken from: http://www.whoi.edu/redtide/page.do?pid=18215
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