(2) the shellfish culture infrastructures were not adequately positioned to intercept
the POM plume; (3) the POM produced by fish sinks very quickly to the bottom
where it is no longer accessible for the filter feeders; (4) shellfish don’t adapt fast
enough to the pulse feeding system used for feeding the fish; (5) they only filter
particulate waste product when the natural plankton production is low; (6) the
seston concentration and size reach the limits where pseudo-faeces are produced.
There are limited interactions between seaweed and bivalve cultures as seaweeds
feed on inorganic nutrients and bivalves on organic nutrients from the water column
and, therefore, can be regarded as co-cultures with separate nutrient models,
although the excretion of metabolic waste products by bivalves enhances the
availability of inorganic nutrients (Jansen 2012).
2.2 Introduction to Extractive Species
Marine extractive species include a large variety of species, which can be subdivided into three main groups among animals and algae: (1) filter feeders, such as
oysters and mussels, (2) deposit feeders, such as polychaetes, sea urchins and sea
cucumbers, as well as (3) dissolved nutrient absorbers, such as microalgae and
macroalgae. These species act as living filters and can be raised without supplemental feed as they take up nutrients for nourishment from the surrounding water
column. While filter and deposit feeders preferentially use small and large POM for
their nutrition, algae extract dissolved inorganic nutrients (DIN) from the water
column. The POM mainly consists of naturally occurring seston and uneaten fish
feed, faeces and bacterial matts in aquaculture operations. The dissolved fraction
consists of inorganic nitrogen (N), phosphorus (P) and carbon (C) available from
nature and released from fed aquaculture operations. As deposit feeders are not yet
often used in offshore environments or in multi-use platforms, they are not discussed further within this chapter.
2.3 IMTA on Offshore Applications
There have been technology exchanges between Asian and western countries. For
example, traditional seaweed cultivation technologies have been exported from
Asia to the West, while the concept of ecosystem services (Costanza et al. 1997) has
been transferred to Asia. Scientists in Asia and the West are integrating these
technologies to increase production in an environmentally friendly manner. In turn,
bivalve cultivation was mainly developed in Europe (and to some extend in New
Zealand) and expertise and technology were transferred to North and South
American countries, as well as Asia, Australia and countries in the Pacific Ocean.
One conceptual approach driven by the various stakeholders using coastal waters
is to transfer aquaculture operations away from nearshore areas. Moving the
2 Offshore and Multi-Use Aquaculture with Extractive Species…
25
the POM plume; (3) the POM produced by fish sinks very quickly to the bottom
where it is no longer accessible for the filter feeders; (4) shellfish don’t adapt fast
enough to the pulse feeding system used for feeding the fish; (5) they only filter
particulate waste product when the natural plankton production is low; (6) the
seston concentration and size reach the limits where pseudo-faeces are produced.
There are limited interactions between seaweed and bivalve cultures as seaweeds
feed on inorganic nutrients and bivalves on organic nutrients from the water column
and, therefore, can be regarded as co-cultures with separate nutrient models,
although the excretion of metabolic waste products by bivalves enhances the
availability of inorganic nutrients (Jansen 2012).
2.2 Introduction to Extractive Species
Marine extractive species include a large variety of species, which can be subdivided into three main groups among animals and algae: (1) filter feeders, such as
oysters and mussels, (2) deposit feeders, such as polychaetes, sea urchins and sea
cucumbers, as well as (3) dissolved nutrient absorbers, such as microalgae and
macroalgae. These species act as living filters and can be raised without supplemental feed as they take up nutrients for nourishment from the surrounding water
column. While filter and deposit feeders preferentially use small and large POM for
their nutrition, algae extract dissolved inorganic nutrients (DIN) from the water
column. The POM mainly consists of naturally occurring seston and uneaten fish
feed, faeces and bacterial matts in aquaculture operations. The dissolved fraction
consists of inorganic nitrogen (N), phosphorus (P) and carbon (C) available from
nature and released from fed aquaculture operations. As deposit feeders are not yet
often used in offshore environments or in multi-use platforms, they are not discussed further within this chapter.
2.3 IMTA on Offshore Applications
There have been technology exchanges between Asian and western countries. For
example, traditional seaweed cultivation technologies have been exported from
Asia to the West, while the concept of ecosystem services (Costanza et al. 1997) has
been transferred to Asia. Scientists in Asia and the West are integrating these
technologies to increase production in an environmentally friendly manner. In turn,
bivalve cultivation was mainly developed in Europe (and to some extend in New
Zealand) and expertise and technology were transferred to North and South
American countries, as well as Asia, Australia and countries in the Pacific Ocean.
One conceptual approach driven by the various stakeholders using coastal waters
is to transfer aquaculture operations away from nearshore areas. Moving the
2 Offshore and Multi-Use Aquaculture with Extractive Species…
25