Nutrient pollution fuels harmful algal blooms which have negative impacts on aquatic ecosystems. Blooms can reduce the ability of fish and aquatic life to find food and cause populations to leave or die. They also cause dead zones with little or no oxygen where aquatic life cannot survive. The largest dead zone is in the Gulf of Mexico, caused by nutrient pollution from the Mississippi River basin. Algal blooms also negatively impact humans by contaminating drinking water and causing illness.

1. Subject : MicroalgalTechnology
Presented by
M.Kejapriya
I – M.Sc., Microbiology
Department of Microbiology
Vivekanandha arts and sceince college for women,
veerachipalayam, sankari.

2.  Phytoplankton blooms, micro-algal blooms,
toxic algae, red tides, or harmful algae, are all
terms for naturally occuring phenomena.
 About 300 species of micro algae are reported
at times to form mass occurrence, so called
blooms. Nearly one fourth of these species are
know to produce toxins.
 The scientific community refers to these events
with a generic term, “Harmful algal bloom”
(HAB), recognising that, because a wide range
of organisms is involved and some species
have toxic effects at low cell densities not all

3.  Algal blooms can reduce the ability of fish and
other aquatic life to find food and can cause
entire populations to leave an area or even die.
 Harmful algal blooms cause thick, green muck
that impacts clear water, recreation,
businesses and property values.
 Nutrient pollution fuels the growth of harmful
algal blooms which have negative impacts on
aquatic ecosystems.

4. Algal bloom

5.  Harmful algal blooms sometimes create toxins
that are detrimental to fish and other animals.
After being consumed by small fish and
shellfish, these toxins move up the food chain
and can impact larger animals like sea lions,
turtles, dolphins, birds and manatees.
 Even if algal blooms are not toxic, they can
negatively impact aquatic life by blocking out
sunlight and clogging fish gills.

6.  Nutrient pollution can create dead zones-areas
in water with little or no oxygen-where aquatic
life cannot survive. Also known as hypoxia,
these areas are caused by algal blooms
consuming oxygen as they die and
decompose.
 Aquatic animals-particularly young fish and
seafloor dwellers like crabs and clams-must
leave the affected area to survive.

7.  Over 166 dead zones have been documented
nation wide, affecting water bodies like the
Chesapeake Bay and the Gulf of Mexico.
 The Gulf of Mexico dead zone is the largest in
the United State, measured to be 5,840 square
miles in 2013. It occurs every summer because
of nutrient pollution from the Mississippi river
basin, an area that drains 31upstream states.
 The Mississippi river/Gulf of Mexico Hypoxia
Task Force coordinates nutrient management
in this area.

8.  Acid rain, caused by nutrient pollution in the air,
damages lakes, streams, estuaries, forests and
grasslands across the country.
 Air borne nitrogen compunds nitrogen oxides
contribute to the formation of other air
pollutants such as ground-level ozone, a
component of smog which can restrict visibility.
 Wind and weather can carry ozone many miles
from urbon to rural areas. Ozone pollution can

9. Some of the major harmful effects of algae to
human being are listed below:
HARMFUL TO LIVING STOCK
 The algae are harmful to humans in several
ways. Volvocales, Chlorococcales, Myxophyceae
and several others occur in such a great
abundance in water, that they colour the whole
water either green or blue green and cause the
death of fishes.
 The algae block the gills of the fishes and they
respire during night and make the respiration of
fishes difficult by complete depletion of oxygen.

10.  Sometimes the algae are found in water so
abundantly that they make difficult to drink
water of livestock.
 Some Blue green algae have been reported
poisonous and they directly cause the death of
living stock who drink this contaminated water.

11. BLOCKING OF
PHOTOSYNTHESES
 The epiphytic algae which are
found upon other plants and trees
blocking photosynthesis and
indirectly harm the trees and
plants.
PARASITIC ALGAE
 The well known disease ‘red
rust of tea’ is not caused by any
parasitic fungus but an algal
form Cephaleuros virescens.

12.  This causes havoc to tea plants in Assam tea
gardens. Besides, this parasitic form attacks
several other plants. E.g., Mangifera,
Rhododendron, Coffea, etc.
 The heavy losses are caused to tea and coffee
by this parasitic algal form.
Red rust of tree

13.  Sometimes the filamentous forms of
algae are found in such a great
abundance and net-like behaviour, that
many fishes and other aquatic animals
may get perish in these tangles, and
direct death is inflicted upon them.
FOULING OF SHIPS
 Some algae are attached to the ships,
and this is called fouling of ship.
 The fouling retards the speed of the ship.
 To avoid this nuisance the ships are
preriodically dried up and painted with
copper paint.

14.  Many Blue-green and other algae
contaminate the water of city reservoirs. This
contamination develops a foul odour in the
water and makes the water unhygienic.
 The algae also form some mucilaginous
secretions which are the seats of harmful
bacteria and other pathogens
causing several human and
animal diseases.

15.  Commonly in rainy season, if the wet fabrics
are exposed, within a few days a blue green
algae appears on it and makes the cloth black
spotted and weak. This was serious problem
during the Second World War.
 This algal growth is usually followed by
bacterial infection and the fibre
are completely destroyed.