40 JUNE 2013 • WORLD AQUACULTURE • WWW.WAS.ORG Once spawning of a fish species is under control, larviculture protocols must be established to meet the biological and nutritional demands of larvae. Many copepods are a valuable source of food for fish larval rearing although they are not often used in commercial aquaculture. Interest in the use of copepods in aquaculture has grown since the 1980s (Schipp 2006). They are considered to be “nutritionally superior live feeds” for commercially important cultivated species because they are a valuable source of protein, carbohydrates, enzymes (amylase, protease, exonuclease and esterase) and lipid (with particular regard to fatty acids) (Watanabe 1979, Watanabe et al. 1983, Witt et al. 1984, Shansudin et al. 1997, Toledo et al. 1999) that are essential for larval survival, growth, digestion and metamorphosis (Støttrup 2000; Molejón and Alvarez-Lajonchère 2003, Kleppel et al. 2005). Copepods are primary consumers in the oceans and are perhaps the most numerous metazoans on earth (Ohman and Hirche 2001). Calanoid copepods play a key role in the cycling of nutrients and energy in marine ecosystems by forming a trophodynamic link between primary (phytoplankton) and tertiary (planktivorous fish) production (De-Young 2004). The widespread distribution and abundance of members of this group partially results from adaptation of life history traits to match specific The Effect of Temperature on Acartia grani Hatching Rates Bernardo Sumares, Natacha Nogueira, Maria Emília Cunha physical or chemical environmental conditions or constraints. Among these environmental conditions, temperature is often considered to be the key external factor that affects life history traits and population dynamics of copepods. Variability in temperature characterizes seasonal succession and directly affects copepod reproduction and development (Ianora et al. 1992). Changes in species abundance in the Baltic sea throughout the year have been related to wide variations in salinity and temperature that exceed those of the preferred niche of the calanoid species found there (Holste and Peck 2006). Egg hatching rate and success are also temperature dependent (McLaren 1966, Uye and Fleminger 1976, Ban 1994, Holste and Peck 2006). Furthermore, temperature-dependent hatching patterns are related to spawning temperature (Landry 1975, Uye and Fleminger 1976). Unfortunately the functional response of reproductive success, egg production and hatching to temperature variations in many calanoid species is not well known, having been studied in only a handful of species such as Eurytemora affinis (Gonzalez and Bradley 1994) and a number of Acartia congeners (Tester and Turner 1991, Chinnery and Williams 2004). Among the calanoids, Acartia grani (Sars G.O. 1904) is a small calanoid copepod typical of coastal, semi-confined FIGURE 1. Acartia grani development: (A) viable eggs are dark; (B and C) three stages of nauplii; (D) two stages of copepodites; (E) adult female; (F) adult male.
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