386
14.3.6 Sclerochronology
Sclerochronology is the study of the physical and chemical patterns in temporal
growth rings (daily, sub-daily, or annual) registered in calcified structures of seawater organisms, with the objective to rebuild the life history and its relationship with
environmental processes (Pasten 2016). In fish, the most used calcified structures
are scales, spines, the rays of the fins, and especially, the otoliths.
Besides being frequently used to estimate age and growth of bony fish (i.e.
Francis and Campana 2004; Mendoza 2006; Correia et al. 2009), the otoliths are
also used as natural markers in migration studies (Albuquerque et al. 2012; Daros
et al. 2016), differentiation of fish stocks (i.e. Correia et al. 2011; Geffen et al. 2011;
Silva et al. 2011), determination of spawning site (i.e. Di Franco et al. 2011; Hamer
et al. 2011), and in the study of connectivity between spawning site and coastal
recruiting zones (i.e. Vasconcelos et al. 2009; Reis-Santos et al. 2012). This is possible because, besides CaCO 3 and otoline, other elements are deposited in small
concentrations, and these are not chemically transformed or modified after deposition (Campana and Neilson 1985); they can be used as environmental markers
(Campana et al. 2000).
The chemical composition of the otoliths proved to be a powerful tool to resolve
the population structure of fish characterized by an elevated gene flow, in particular
from migratory species, with a long pelagic larvae stage, especially when there is
environmental heterogeneity reflected in the chemical composition of the otoliths
(Bradbury et al. 2008; Selkoe et al. 2008; Smith and Campana 2010). The knowledge regarding the ecology of fish species is fundamental to identify the population
units or stocks, the identification of migratory routes, and the study of connectivity
between the spawning zones or nurseries, and the respective recruiting and growth
coastal zones. This information is fundamental to a more integrated and rational
management of fish resources, as well as for the protection of threatened species
due to overfishing (Stephenson 1999), and the creation of protected seawater network (Palumbi et al. 2013; Cook 2014).
However, the extraction of otoliths requires the kill of fish, and when the study is
focused on protected or threatened species, the use of non-lethal sampling is preferred (Willmes et al. 2016). Other calcified tissues (i.e. scale, rays and spines, and
dorsal scute), other than otoliths are mostly composed by aragonite. These tissues
are composed of biological apatite (Willmes et al. 2016), where the incorporation of
ions occurs via the blood (Veinott and Evans 1999), which is different from otoliths,
where ions are incorporated directly from the endolymph (Campana and Neilson
1995). These structures also provide valuable information in studies, as for example, the chemical signature of the areas of spawning and nursing, age and growth
(Fig. 14.10) and ontogenetic migration (Clarke et al. 2007; Brushei and Schull
2009; Smith and Whitledge 2010; Tzadik et al. 2014; Altenritter and Kinnison 2015;
Linley et al. 2016), once these tissues present an internal structure in layers, which
correspond to periods in time, similar to the otoliths (Erickson 1983). Already tested
by other authors, the rays from the dorsal fin of the Goliath Grouper are useful to
M. Hostim-Silva et al.
14.3.6 Sclerochronology
Sclerochronology is the study of the physical and chemical patterns in temporal
growth rings (daily, sub-daily, or annual) registered in calcified structures of seawater organisms, with the objective to rebuild the life history and its relationship with
environmental processes (Pasten 2016). In fish, the most used calcified structures
are scales, spines, the rays of the fins, and especially, the otoliths.
Besides being frequently used to estimate age and growth of bony fish (i.e.
Francis and Campana 2004; Mendoza 2006; Correia et al. 2009), the otoliths are
also used as natural markers in migration studies (Albuquerque et al. 2012; Daros
et al. 2016), differentiation of fish stocks (i.e. Correia et al. 2011; Geffen et al. 2011;
Silva et al. 2011), determination of spawning site (i.e. Di Franco et al. 2011; Hamer
et al. 2011), and in the study of connectivity between spawning site and coastal
recruiting zones (i.e. Vasconcelos et al. 2009; Reis-Santos et al. 2012). This is possible because, besides CaCO 3 and otoline, other elements are deposited in small
concentrations, and these are not chemically transformed or modified after deposition (Campana and Neilson 1985); they can be used as environmental markers
(Campana et al. 2000).
The chemical composition of the otoliths proved to be a powerful tool to resolve
the population structure of fish characterized by an elevated gene flow, in particular
from migratory species, with a long pelagic larvae stage, especially when there is
environmental heterogeneity reflected in the chemical composition of the otoliths
(Bradbury et al. 2008; Selkoe et al. 2008; Smith and Campana 2010). The knowledge regarding the ecology of fish species is fundamental to identify the population
units or stocks, the identification of migratory routes, and the study of connectivity
between the spawning zones or nurseries, and the respective recruiting and growth
coastal zones. This information is fundamental to a more integrated and rational
management of fish resources, as well as for the protection of threatened species
due to overfishing (Stephenson 1999), and the creation of protected seawater network (Palumbi et al. 2013; Cook 2014).
However, the extraction of otoliths requires the kill of fish, and when the study is
focused on protected or threatened species, the use of non-lethal sampling is preferred (Willmes et al. 2016). Other calcified tissues (i.e. scale, rays and spines, and
dorsal scute), other than otoliths are mostly composed by aragonite. These tissues
are composed of biological apatite (Willmes et al. 2016), where the incorporation of
ions occurs via the blood (Veinott and Evans 1999), which is different from otoliths,
where ions are incorporated directly from the endolymph (Campana and Neilson
1995). These structures also provide valuable information in studies, as for example, the chemical signature of the areas of spawning and nursing, age and growth
(Fig. 14.10) and ontogenetic migration (Clarke et al. 2007; Brushei and Schull
2009; Smith and Whitledge 2010; Tzadik et al. 2014; Altenritter and Kinnison 2015;
Linley et al. 2016), once these tissues present an internal structure in layers, which
correspond to periods in time, similar to the otoliths (Erickson 1983). Already tested
by other authors, the rays from the dorsal fin of the Goliath Grouper are useful to
M. Hostim-Silva et al.