Algae and Fishes: Benefits and Hazards
475
Invasive species can harm the ecological balance and cause the death of important
local organisms especially if those invasive species include toxic algae that overgrow
and outcompete native species and cause massive fish mortality in addition to lowering the quality of recreational and drinking water. On the economic level, biofouling
can cause loss of productivity in aquaculture.
Therefore, there is a necessity for early surveillance of water bodies and complementing this with environmental data that include all relevant information including
substrate nature, community structure, interrelations between different community
members and ecological parameters associated with this phenomenon. Alarmingly,
the continual rise of sea levels together with recurrent catastrophic natural disaster of
tsunami has exposed wide terrestrial coastal areas, objects and vehicles to invasion
by marine microalgae, some of which are toxic which in turn lead to contamination
of local water bodies as recorded in villages in Southern India [43].
Another overlooked hazard is ballast water which is the water used by oil and
cargo tankers to maintain its balance until being fully loaded with its cargo. The
water is then disposed of in the hosting port. Because of the richness of this water by
non-indigenous living organisms of algae and other biological forms, they pose an
environmental danger and can cause serious ecological damages. Invasive harmful
or toxic species can cause environmental imbalance where these organisms can be
spread and compete with local organisms for their food resources.
They may also devour many of them or produce toxins causing disease or death,
which poses a huge threat to the local environment. In addition, discharge of ballast
water may cause sediments in those waters to increase the acidity and mortality of
marine larvae (http://main.omanobserver.om/?p=57413).
In 2014, Sultanate Oman held an International conference on the management of
ballast water discharge and marine invasive species. One of the key topics addressed
was “Biofouling on ship hulls: The vector for moving marine invasive species”.
Light was also shed on the intensity & frequency of Harmful Algal Blooms (HABs)
in the coastal water of Oman and a look at harmful algal blooms (including invasive
species) and their effect in Oman waters and regional water as well with experts
attending from all over the world and recognizing the magnitude of the problem.
Quite recently, The International Convention for the Control and Management
of Ships’ Ballast Water and Sediments (BWM) has come to force by the end
of 2017 (https://www.imo.org/en/About/Conventions/ListOfConventions/Pages/
International-Convention-for-the-Control-and-Management-of-Ships’-BallastWater-and-Sediments-(BWM).aspx). This convention requires aquatic vessels to
keep records of sources of ballast water and dates of renewal. Samples are to be
taken regularly to check for any harmful species present.
Therefore, it is important to both recognize the factors leading to biofouling as well
as the types of algae able to biofoul aquatic structures. It is worthy noting that some of
the most important factors that are most likely to affect the algal community include
temperature, light intensity, pH, nutrient status (mainly P and N), dissolved oxygen
[44] and substrate nature. For example, In the Foa reviews, [45, 46], http://www.fao.
org/docrep/012/i1141e/i1141e01.pdf and http://www.fao.org/docrep/003/W3732E/
w3732e08.htm, listed some of the growth condition requirements of several algal
475
Invasive species can harm the ecological balance and cause the death of important
local organisms especially if those invasive species include toxic algae that overgrow
and outcompete native species and cause massive fish mortality in addition to lowering the quality of recreational and drinking water. On the economic level, biofouling
can cause loss of productivity in aquaculture.
Therefore, there is a necessity for early surveillance of water bodies and complementing this with environmental data that include all relevant information including
substrate nature, community structure, interrelations between different community
members and ecological parameters associated with this phenomenon. Alarmingly,
the continual rise of sea levels together with recurrent catastrophic natural disaster of
tsunami has exposed wide terrestrial coastal areas, objects and vehicles to invasion
by marine microalgae, some of which are toxic which in turn lead to contamination
of local water bodies as recorded in villages in Southern India [43].
Another overlooked hazard is ballast water which is the water used by oil and
cargo tankers to maintain its balance until being fully loaded with its cargo. The
water is then disposed of in the hosting port. Because of the richness of this water by
non-indigenous living organisms of algae and other biological forms, they pose an
environmental danger and can cause serious ecological damages. Invasive harmful
or toxic species can cause environmental imbalance where these organisms can be
spread and compete with local organisms for their food resources.
They may also devour many of them or produce toxins causing disease or death,
which poses a huge threat to the local environment. In addition, discharge of ballast
water may cause sediments in those waters to increase the acidity and mortality of
marine larvae (http://main.omanobserver.om/?p=57413).
In 2014, Sultanate Oman held an International conference on the management of
ballast water discharge and marine invasive species. One of the key topics addressed
was “Biofouling on ship hulls: The vector for moving marine invasive species”.
Light was also shed on the intensity & frequency of Harmful Algal Blooms (HABs)
in the coastal water of Oman and a look at harmful algal blooms (including invasive
species) and their effect in Oman waters and regional water as well with experts
attending from all over the world and recognizing the magnitude of the problem.
Quite recently, The International Convention for the Control and Management
of Ships’ Ballast Water and Sediments (BWM) has come to force by the end
of 2017 (https://www.imo.org/en/About/Conventions/ListOfConventions/Pages/
International-Convention-for-the-Control-and-Management-of-Ships’-BallastWater-and-Sediments-(BWM).aspx). This convention requires aquatic vessels to
keep records of sources of ballast water and dates of renewal. Samples are to be
taken regularly to check for any harmful species present.
Therefore, it is important to both recognize the factors leading to biofouling as well
as the types of algae able to biofoul aquatic structures. It is worthy noting that some of
the most important factors that are most likely to affect the algal community include
temperature, light intensity, pH, nutrient status (mainly P and N), dissolved oxygen
[44] and substrate nature. For example, In the Foa reviews, [45, 46], http://www.fao.
org/docrep/012/i1141e/i1141e01.pdf and http://www.fao.org/docrep/003/W3732E/
w3732e08.htm, listed some of the growth condition requirements of several algal