Algae and Fishes: Benefits and Hazards
467
numbers in the open oceans through iron fertilization with a subsequent increase in
phytoplanktons leading to the increase in the number of aquatic animals. However,
this scenario has not been fully achieved and results so far are hereby discussed.
On the other hand, not all algae are beneficial. Some algae are toxic as they produce
toxins that cause massive fish mortalities. They can be transferred from one water
body to another and from a country to another through ballast water and/or biofouling.
These overlooked hazards can jeopardize marine food security and endanger local
environments. Thereby, surveillance and tight monitoring are needed. The current
chapter raises concerns about those overlooked hazards.
1.2 Microalgae in Aquaculture
According to FAO report on the use of microalgae in aquaculture, all stages of
marine bivalve molluscs such as clams, oysters, scallops are feeding on live algae
as well as the larval stages of some marine gastropods (abalone, conch), larvae of
several marine fish species and penaeid shrimp, and zooplankton hatchery. Eight algal
species (Isochrysis sp.; Chaetoceros gracilis; Chaetoceros calcitrans; Tetraselmis
suecica; Thalassiosiera pseudonana, clone 3H; Pavlova lutheri; Isochrysis galbana;
Skeletonema costatum are usually used for feeding through active uptake by the
larvae of polysaccharides present in the algal cell walls. Algae can also play a role
in stabilizing the water quality via removal of wastes and production of oxygen as
well as the possible stimulation of the non-specific immune system in the larvae
(http://www.fao.org/docrep/003/W3732E/w3732e08.htm).
1.3 Description of the System of Inland Aquaculture
The use of underground water for culturing aquatic animals in desert areas is a
relatively new approach. The underground water receives no domestic or industrial
wastewater, thereby providing a fairly unpolluted thermal water source suitable for
their growth. The desert provides a geographical barrier that protects aquacultures
against disease and pathogens. The water is either freshwater or slightly brackish.
The wastewater of the fish culture is recycled to grow plants as it is rich in phosphate
and ammonia. This maximizes water usage efficiency and decreases the usage of
hazardous chemical fertilisers. Algae can be grown in man-made ponds to provide
feed for aquatic animals grown. A small-scale study was carried out to validate the
use of algae grown on brackish water collected from Wadi El Natroun, Western
desert, Egypt as fish feed and the use of fish waste water for growing plants and the
results were highly encouraging [3]. The algae to be grown are to be fed to fishes as
a dietary supplement or main meal for larvae.
467
numbers in the open oceans through iron fertilization with a subsequent increase in
phytoplanktons leading to the increase in the number of aquatic animals. However,
this scenario has not been fully achieved and results so far are hereby discussed.
On the other hand, not all algae are beneficial. Some algae are toxic as they produce
toxins that cause massive fish mortalities. They can be transferred from one water
body to another and from a country to another through ballast water and/or biofouling.
These overlooked hazards can jeopardize marine food security and endanger local
environments. Thereby, surveillance and tight monitoring are needed. The current
chapter raises concerns about those overlooked hazards.
1.2 Microalgae in Aquaculture
According to FAO report on the use of microalgae in aquaculture, all stages of
marine bivalve molluscs such as clams, oysters, scallops are feeding on live algae
as well as the larval stages of some marine gastropods (abalone, conch), larvae of
several marine fish species and penaeid shrimp, and zooplankton hatchery. Eight algal
species (Isochrysis sp.; Chaetoceros gracilis; Chaetoceros calcitrans; Tetraselmis
suecica; Thalassiosiera pseudonana, clone 3H; Pavlova lutheri; Isochrysis galbana;
Skeletonema costatum are usually used for feeding through active uptake by the
larvae of polysaccharides present in the algal cell walls. Algae can also play a role
in stabilizing the water quality via removal of wastes and production of oxygen as
well as the possible stimulation of the non-specific immune system in the larvae
(http://www.fao.org/docrep/003/W3732E/w3732e08.htm).
1.3 Description of the System of Inland Aquaculture
The use of underground water for culturing aquatic animals in desert areas is a
relatively new approach. The underground water receives no domestic or industrial
wastewater, thereby providing a fairly unpolluted thermal water source suitable for
their growth. The desert provides a geographical barrier that protects aquacultures
against disease and pathogens. The water is either freshwater or slightly brackish.
The wastewater of the fish culture is recycled to grow plants as it is rich in phosphate
and ammonia. This maximizes water usage efficiency and decreases the usage of
hazardous chemical fertilisers. Algae can be grown in man-made ponds to provide
feed for aquatic animals grown. A small-scale study was carried out to validate the
use of algae grown on brackish water collected from Wadi El Natroun, Western
desert, Egypt as fish feed and the use of fish waste water for growing plants and the
results were highly encouraging [3]. The algae to be grown are to be fed to fishes as
a dietary supplement or main meal for larvae.