326
year with an annual value of US $29 million (FAO 2017). Most of the biomass is
used in the phycocolloid industry as the main source of food grade agar (Pereira and
Yarish 2008) and as an animal feed (Qi et al. 2010; Johnson et al. 2014). Gracilaria/
Gracilariopsis contribute approximately 66% of the total agar production (Pereira
and Yarish 2008). Currently 185 Gracilaria and 24 Gracilariopsis species are
accepted taxonomically (Guiry and Guiry 2016). Gracilaria/Gracilariopsis include
warm temperate to subtropical eurythermal species. These species are easy to propagate (asexually and sexually), and have relatively high growth rates (Abreu et al.
2011a; Kim and Yarish 2014; Kim et al. 2015, 2016; Wu et al. 2015; Gorman et al.
2017). Gracilaria/Gracilariopsis are also euryhaline species, which can tolerate a
wide range of salinities, from about 10–40 psu, though they grow best in ranges of
25–33 psu (Yokoya et al. 1999; Weinberger et al. 2008; Kim et al. 2016; Gorman
et al. 2017). They can survive temperature ranges from 0 to 35 °C but have an optimal range of 20–28 °C (Yokoya et al. 1999; Raikar et al. 2001; Abreu et al. 2011a;
Kim et al. 2016).
Gracilaria/Gracilariopsis have been cultivated mainly in four different ways,
including open water rope cultivation, near shore bottom cultivation, pond culture
and tank cultures (see Oliveira et al. 2000; Sahoo and Yarish 2005; Pereira and
Yarish 2008 for more details). In any of these methods, providing sustainable seedstock is critical. Currently, most Gracilaria/Gracilariopsis seedstock has been supplied from the wild (either collection of healthy branches of Gracilaria/Gracilariopsis
from natural stock or selection of reproductive plants to collect spores (either carpospores or tetraspores) for seeding (Buschmann et al. 2008). Dependence on natural
stocks may cause some serious problems including physiological variations (e.g.,
growth, agar content, etc.) in the seedstock. Adequate measures should be taken to
protect natural stocks of Gracilaria/Gracilariopsis from over-exploitation of donor
populations. Another methodology that could be used is nursery (tank culture) systems to provide sufficient seedstock through vegetative propagation (Hanisak 1987;
Abreu et al. 2011a, b; Kim and Yarish 2014). One important advantage of tank
cultivation is the ease of controlling the culture system (Abreu et al. 2011b; Pereira
et al. 2013). This ensures that production meets high quality standards and biosafety
for human consumption and other high value production applications for the cosmeceutical and pharmaceutical industries. A limitation for tank culture, however, is
high management costs (Hanisak and Ryther 1984, Caines et al. 2014). Recently,
Abreu et al. (2011b) have used tank cultivation to mitigate fish effluent, therefore
reducing the production costs. Kim and Yarish (2014) has also suggested other cost
efficient resources, such as injecting CO2 and using commercial fertilizers. The use
of LED lighting could further reduce tank cultivation costs (Kim et al. 2015). There
was an intensive study on genetics, mutation, selective breeding and even genetic
engineering in Gracilaria/Gracilariopsis by van der Meer and his collaborators a few
dacades ago (see Patwary and van der Meer 1992 and references therein). More
recently in Chile, strains of Gracilaria chilensis were established and maintained
without sexual reproduction. These strains are homogeneous clonal cultures
(Buschmann et al. 2008; Guillemin et al. 2008; Robinson et al. 2013), which can be
9 Mangroves: A Source of Existing and Alternative Livelihood
year with an annual value of US $29 million (FAO 2017). Most of the biomass is
used in the phycocolloid industry as the main source of food grade agar (Pereira and
Yarish 2008) and as an animal feed (Qi et al. 2010; Johnson et al. 2014). Gracilaria/
Gracilariopsis contribute approximately 66% of the total agar production (Pereira
and Yarish 2008). Currently 185 Gracilaria and 24 Gracilariopsis species are
accepted taxonomically (Guiry and Guiry 2016). Gracilaria/Gracilariopsis include
warm temperate to subtropical eurythermal species. These species are easy to propagate (asexually and sexually), and have relatively high growth rates (Abreu et al.
2011a; Kim and Yarish 2014; Kim et al. 2015, 2016; Wu et al. 2015; Gorman et al.
2017). Gracilaria/Gracilariopsis are also euryhaline species, which can tolerate a
wide range of salinities, from about 10–40 psu, though they grow best in ranges of
25–33 psu (Yokoya et al. 1999; Weinberger et al. 2008; Kim et al. 2016; Gorman
et al. 2017). They can survive temperature ranges from 0 to 35 °C but have an optimal range of 20–28 °C (Yokoya et al. 1999; Raikar et al. 2001; Abreu et al. 2011a;
Kim et al. 2016).
Gracilaria/Gracilariopsis have been cultivated mainly in four different ways,
including open water rope cultivation, near shore bottom cultivation, pond culture
and tank cultures (see Oliveira et al. 2000; Sahoo and Yarish 2005; Pereira and
Yarish 2008 for more details). In any of these methods, providing sustainable seedstock is critical. Currently, most Gracilaria/Gracilariopsis seedstock has been supplied from the wild (either collection of healthy branches of Gracilaria/Gracilariopsis
from natural stock or selection of reproductive plants to collect spores (either carpospores or tetraspores) for seeding (Buschmann et al. 2008). Dependence on natural
stocks may cause some serious problems including physiological variations (e.g.,
growth, agar content, etc.) in the seedstock. Adequate measures should be taken to
protect natural stocks of Gracilaria/Gracilariopsis from over-exploitation of donor
populations. Another methodology that could be used is nursery (tank culture) systems to provide sufficient seedstock through vegetative propagation (Hanisak 1987;
Abreu et al. 2011a, b; Kim and Yarish 2014). One important advantage of tank
cultivation is the ease of controlling the culture system (Abreu et al. 2011b; Pereira
et al. 2013). This ensures that production meets high quality standards and biosafety
for human consumption and other high value production applications for the cosmeceutical and pharmaceutical industries. A limitation for tank culture, however, is
high management costs (Hanisak and Ryther 1984, Caines et al. 2014). Recently,
Abreu et al. (2011b) have used tank cultivation to mitigate fish effluent, therefore
reducing the production costs. Kim and Yarish (2014) has also suggested other cost
efficient resources, such as injecting CO2 and using commercial fertilizers. The use
of LED lighting could further reduce tank cultivation costs (Kim et al. 2015). There
was an intensive study on genetics, mutation, selective breeding and even genetic
engineering in Gracilaria/Gracilariopsis by van der Meer and his collaborators a few
dacades ago (see Patwary and van der Meer 1992 and references therein). More
recently in Chile, strains of Gracilaria chilensis were established and maintained
without sexual reproduction. These strains are homogeneous clonal cultures
(Buschmann et al. 2008; Guillemin et al. 2008; Robinson et al. 2013), which can be
9 Mangroves: A Source of Existing and Alternative Livelihood