species, showing strong correlations with RNA/DNA ratios in other fish species (Clemmessen and Doan 1996). However, the studies conducted in the North
Alboran Sea with sardine larvae show that the RNA/DNA ratios in larvae is
generally highly variable. This may be due to a more rapid response of RNA to
exogenous factors, such as temperature (Goolish et al. 1984), while changes related
with somatic and otolith growth rates have a slower response to external factors
(Ramírez et al. 2004).
On the other hand, the studies conducted with sardine larvae collected in the
northwestern Alboran Sea revealed that RNA, DNA, protein, and carbohydrate
content of larvae is highly dependent on larval age, length, and weight (Ramírez
et al. 2001; Ramírez et al. 2004; Cortés 2006). Although both length and weight at a
given age are indicators of somatic growth, according to the research on sardine
larvae in the Alboran Sea, weight accounts for a higher percent of variability in
biochemical parameters than larval length (García et al. 2005). This higher dependence on weight can be explained by the fact that these biochemical parameters are
intrinsically related to cell metabolism and tissue accretion.
Although larval growth is highly influenced by the surrounding hydrobiological
conditions predominating in their nursery sites, the influence of maternal qualities
cannot be overlooked (Høie et al. 1999; Green and McCormick 2005; Uriarte et al.
2016). Recent results have shown that pre-flexion larvae of bluefin reared under
controlled laboratory conditions showed maternal transmission of the stable isotopes
of carbon and nitrogen (Uriarte et al. 2016) enabling future prospects of analyzing
the trophodynamics of spawning females.
13.5.3 Seasonal and Interannual Variability of Larval
Growth and Condition Research
The temporal variability of larval growth and condition (RNA/DNA) research of
larval stages of sardines and anchovies was enabled by the ECOMALAGA sampling
time series. The temporal and seasonal variability of larval sardine (García 2006;
Cortés 2006) and an interannual comparison of anchovy larvae (García et al. 2003)
allowed investigating the environmental and climatic drivers that influence ELHS
development.
ANCOVA using daily increments (DI) as covariant showed highest sizes at age
(SL) and dry weight (DW) at age between comparably equal larval size classes of
sardine larval cohorts, which is consequential to having greater daily growth rates.
Maximum growth corresponded to maximum DNA and RNA content during the
winters of 1995 and 2001 (Fig. 13.15). During spring, the sardine larval cohorts of
1998 and 2001 showed highest growth rates.
Motivated by the faster is better hypothesis whereby faster-growing individuals
are prone to have higher survival rates (Houde 1987; Anderson 1988; Meekan et al.
508
A. García et al.
Alboran Sea with sardine larvae show that the RNA/DNA ratios in larvae is
generally highly variable. This may be due to a more rapid response of RNA to
exogenous factors, such as temperature (Goolish et al. 1984), while changes related
with somatic and otolith growth rates have a slower response to external factors
(Ramírez et al. 2004).
On the other hand, the studies conducted with sardine larvae collected in the
northwestern Alboran Sea revealed that RNA, DNA, protein, and carbohydrate
content of larvae is highly dependent on larval age, length, and weight (Ramírez
et al. 2001; Ramírez et al. 2004; Cortés 2006). Although both length and weight at a
given age are indicators of somatic growth, according to the research on sardine
larvae in the Alboran Sea, weight accounts for a higher percent of variability in
biochemical parameters than larval length (García et al. 2005). This higher dependence on weight can be explained by the fact that these biochemical parameters are
intrinsically related to cell metabolism and tissue accretion.
Although larval growth is highly influenced by the surrounding hydrobiological
conditions predominating in their nursery sites, the influence of maternal qualities
cannot be overlooked (Høie et al. 1999; Green and McCormick 2005; Uriarte et al.
2016). Recent results have shown that pre-flexion larvae of bluefin reared under
controlled laboratory conditions showed maternal transmission of the stable isotopes
of carbon and nitrogen (Uriarte et al. 2016) enabling future prospects of analyzing
the trophodynamics of spawning females.
13.5.3 Seasonal and Interannual Variability of Larval
Growth and Condition Research
The temporal variability of larval growth and condition (RNA/DNA) research of
larval stages of sardines and anchovies was enabled by the ECOMALAGA sampling
time series. The temporal and seasonal variability of larval sardine (García 2006;
Cortés 2006) and an interannual comparison of anchovy larvae (García et al. 2003)
allowed investigating the environmental and climatic drivers that influence ELHS
development.
ANCOVA using daily increments (DI) as covariant showed highest sizes at age
(SL) and dry weight (DW) at age between comparably equal larval size classes of
sardine larval cohorts, which is consequential to having greater daily growth rates.
Maximum growth corresponded to maximum DNA and RNA content during the
winters of 1995 and 2001 (Fig. 13.15). During spring, the sardine larval cohorts of
1998 and 2001 showed highest growth rates.
Motivated by the faster is better hypothesis whereby faster-growing individuals
are prone to have higher survival rates (Houde 1987; Anderson 1988; Meekan et al.
508
A. García et al.