red tide effect

1. RED TIDE EFFECT ON MARINE FAUNA
Presentedby...
Nibedita swain

2. INTRODUCTION:
Red tide is a common name for a
phenomenon more correctly known as algal
bloom. It is an event in which estuarine,
marine or fresh water algal accumulate
rapidly in the water column & result in
discoloration of surface water. Red tide have
important ecological, social & even economic
consequences.

3. WHAT IS RED TIDE?
 It is not camouflage of phytoplanktons, certain
species of phytoplankton such as dinoflagellate
contain photo synthetic pigments that vary in
colour from green to brown to red.
 Dinoflagellates (Gr. Dinos-whirling &
L.flagellum-whip) are unicellular protists which
exhibit a great diversity of form chlorophyceae,
cyanophyceae & Rhodophyceae impact their
pigments colour on surfacewater.
 When algae are present in high concentration
water appear to be discoloured. Not all algal
blooms are dense enough to cause water
discoloration & not all water discolorations are
associated with algal bloom.

4. RED TIDE SEEN IN FLORIDA IN 2005

5. RED TIDE AT NIGHT

6. TOXIC EFFECT:
 Some red tides are associated with the production of
natural toxins,deplection of dissolved oxygen & other
harmful effects.
 Some natural toxins are brevetoxin,domic
acid,saxitoxin etc.
 Karenia brevis a dinoflagellate that produce the toxic
substance brevetoxin,diatoms in the genus Nitzchia
synthesize domic acid,saxitoxin is produced by
certain species of marine dinoflagellates such as the
Alexandrium species.These are considered as algal
blooms.
 The toxic effect of red tide usually depends on the
level of its concentration.

7. DINOFLAGELLATES UNDER MICROSCOPE

8. DINOFLAGELLATE

9. FACTORS THAT PROMOTE RED TIDE:
Five important factors that promote Red tide are:-
1.Warm Temperature
2.Nutrient Supply
3.Low Salinity
4.Calm Seas
5.Rain followed by sunny weather
 Warm temperature i.e 26.70C to 30.60C of sea water temperature
is favourable for growth of Red tide Noctiluca scintillans.
 Growth of marine phytoplanktons are generally limited by the
availability of nitrates & phosphates, which can be abundant in
agricultural runoff as well as coastal upwelling zones & iron-
rich dust influx from large desert areas such as Sahara desert
which play great role in promoting Red tide.
 Low salinity, calm seas & the rain followed by sunny weather all
these promote Red tide

10. STAGES OF DEVELOPMENT:
 Scientists have summerized the development of Red tide
into three stages:- 1.Planktonic Stage
2.Growth Stage
3.Maintenance Stage
 During planktonic stage planktons are introduced into the
area that is less dense.
 Next is growth stage where planktonic population begins
to multiply rapidly over a few week time span.
 During maintenance stage growth reaches to peak then
either continue to live off shore or can be moved inshore
by tides or strong winds.
 If the blooms move closer to the shore where nutrient
supply is in great abundance, the blooms can grow ever
larger.
 The last stage is dissipate ending stage where plankton
completes its life cycle & enter to a new cycle.

11. EFFECTS:
 Effect of Red tide are associated with wildlife mortalities among marine
& coastal species of fishes, birds,mammals & other organisms.
 The mollusc banded tulip,Crown conch & lettered olive lost muscle
control.
 These are filter feeders & are contaminated when feed upon
phytoplanktons having brevetoxine or any other type of natural toxin.
 Brevetoxin is absorbed directly across the gill membrane of fish or
through ingestion of Karenia brevis cells leading to death of the fishes.
 When dinoflagellate Gyrodinium corsicum cells attach to copepod
surface at the urosome & antennae;causes noxious toxic effects leading
disruption of the mechanical & chemical sensory systems.
 Presence of brevetoxin in nasal & lung tissue implicates the aerosol &
sever inflammatory lesions of the upper respiratory tract as seen in
dugongs.

12. DEAD FISHES DUE TO RED TIDE

13. AFFECTED SHELLFISHES DUE TO
RED TIDE

14. RESULTED SYMPTOMS:
 Fishes show violent twisting & cork screw swimming,
defecation, pectoral fin-paralysis, caudal curvature, loss of
equilibrium & culminating in death due to respiratory
failure.
 Increased lethargy & muscle weakness in loggerhead sea
turtles causes these animals to wash ashore in a decreased
metabolic state.
 Paralytic shell-fish poisoning, Diarrhetic shell fish poisoning
are the resulted effects along with symptoms in human
contaminated with infected shell fish.

15. PARALYTIC SHELLFISH POISONING(PSP):
 This disease is caused by the production of saxitoxin
by the Alexandrium species.
 It is common along the Atlantic & Pacific coasts in
the US & Canada.
 Poisoning occurs when one ingests shellfish
contaminated with PSP toxin causing disruption of
nerve function & paralysis.
 Extreme cases may result in death by asphyxiation by
respiratory paralysis.

16. DIARRHETIC SHELLFISH POISONING(DSP):
This disease is caused by the Dinophysis
species.
It generally occurs in Japan & Europe.
Symptoms of DSP include diarrhea,
nausea, vomiting, abdominal pain &
cramps.
DSP is generally not lethal.

17. EFFECTOF RED TIDE IN HUMAN SOCIETY:
After all Red tide is able to infect human
beings. Red tide toxins that are carried over
land by wind can cause temporary problems
in people including coughing, sneezing &
watery eyes. Swimming in water having Red
tide may cause skin irritation & burning eyes
sensation.

19. REFERENCE
 “Red Tide FAQ”. www.tpwd.state.tx.us. Retrieved 2009-08-23.
 Florida Fish & wildlife Research Institute. “Red Tide current
status state wide information”. Research.myfwc.com Retrieved
2009-08-23.
 “Red Tide Index”. www.tpwd.state.tx.us. Retrieved 2009-08-23.
 “Harmful Algal Bloom: Red Tide: Home”. CDC HSB. Retrieved
2009-08-23.

20. THANK YOU