Algae and Fishes: Benefits and Hazards
Nermin Adel Hussein El Semary
Abstract Aquatic animals such as fish and crustaceans provide human beings with
high-quality protein diets. Meals of aquatic animals are based partially or even
entirely on algae. Marine algae can be grown as maricultures in marine environments in various forms. Also, algae can be used for fish diets in inland aquacultures.
Algae can also be grown not only for their nutritional value but also for their pigments
that can affect the colour and health of some aquatic animals thereby affecting their
quality and marketability. However, algal phytoplanktons are not massive in large
areas of major oceans. The reason behind that lies in the deficiency of iron despite the
presence of other major nutrients such as phosphorus and nitrogen in high concentrations. Recently this iron limitation in marine environments attracted the attention
of scientists. Thirteen iron fertilisation experiments in those oceans were performed
to enrich them with iron which in turn would lead to the increase of the phytoplankton and consequently aquatic animals and fishes. Scientists propose that this would
cause mitigation of global warming as algae take in carbon dioxide, the main factor
responsible for global warming, and release oxygen during photosynthesis. So double benefits are expected in terms of increasing aquatic animals and decreasing global
warming. However, the short and long-term overall effects of those experiments are
yet to be validated and evaluated. On the other hand, some algae can have a negative
impact on fishes. Toxic algae can cause massive fish mortalities. The two main algal
groups responsible for toxins production are cyanobacteria and dinoflagellates. They
can spread from one water body to another through ballast water or via biofouling
aquatic vessels such as ships and boats. This, in turn, would be harmful and even
lethal for aquatic animals and would jeopardize food security. Thereby, surveillance
of aquatic vessels must be performed.
Keywords Algae · Fish · Fisheries · Crustaceans · Iron fertilisation · Mariculture
N. A. H. El Semary (B)
Biological Sciences Department, College of Science, King Faisal University, 31982 Al Ahsa,
Kingdom of Saudi Arabia
e-mail: nelsemary@kfu.edu.sa
Botany and Microbiology Department, Faculty of Science, Helwan University, 11795 Cairo, Egypt
© Springer Nature Switzerland AG 2020
E.-S. E. Omran and A. M. Negm (eds.), Climate Change Impacts on Agriculture and Food
Security in Egypt, Springer Water, https://doi.org/10.1007/978-3-030-41629-4_19
465
Nermin Adel Hussein El Semary
Abstract Aquatic animals such as fish and crustaceans provide human beings with
high-quality protein diets. Meals of aquatic animals are based partially or even
entirely on algae. Marine algae can be grown as maricultures in marine environments in various forms. Also, algae can be used for fish diets in inland aquacultures.
Algae can also be grown not only for their nutritional value but also for their pigments
that can affect the colour and health of some aquatic animals thereby affecting their
quality and marketability. However, algal phytoplanktons are not massive in large
areas of major oceans. The reason behind that lies in the deficiency of iron despite the
presence of other major nutrients such as phosphorus and nitrogen in high concentrations. Recently this iron limitation in marine environments attracted the attention
of scientists. Thirteen iron fertilisation experiments in those oceans were performed
to enrich them with iron which in turn would lead to the increase of the phytoplankton and consequently aquatic animals and fishes. Scientists propose that this would
cause mitigation of global warming as algae take in carbon dioxide, the main factor
responsible for global warming, and release oxygen during photosynthesis. So double benefits are expected in terms of increasing aquatic animals and decreasing global
warming. However, the short and long-term overall effects of those experiments are
yet to be validated and evaluated. On the other hand, some algae can have a negative
impact on fishes. Toxic algae can cause massive fish mortalities. The two main algal
groups responsible for toxins production are cyanobacteria and dinoflagellates. They
can spread from one water body to another through ballast water or via biofouling
aquatic vessels such as ships and boats. This, in turn, would be harmful and even
lethal for aquatic animals and would jeopardize food security. Thereby, surveillance
of aquatic vessels must be performed.
Keywords Algae · Fish · Fisheries · Crustaceans · Iron fertilisation · Mariculture
N. A. H. El Semary (B)
Biological Sciences Department, College of Science, King Faisal University, 31982 Al Ahsa,
Kingdom of Saudi Arabia
e-mail: nelsemary@kfu.edu.sa
Botany and Microbiology Department, Faculty of Science, Helwan University, 11795 Cairo, Egypt
© Springer Nature Switzerland AG 2020
E.-S. E. Omran and A. M. Negm (eds.), Climate Change Impacts on Agriculture and Food
Security in Egypt, Springer Water, https://doi.org/10.1007/978-3-030-41629-4_19
465