Effects of incubation temperature on development and yolk sac conversion efficiencies of spotted wolffish (Anarhichas minor Olafsen) embryos until hatch

Abstract

Two egg batches of spotted wol⁄sh, Anarhichas minor Olafsen, were incubated at 4, 6 and 8 1C. Embryo samples were ¢xed and compared on each100th daydegree until hatching (up to 1000 daydegrees). Embryos, yolk sacs and chorions were dissected and the sizes, wet and dry weights were recorded separately. Comparisons of gross morphologies and measured parameters showed increasing and generally signi¢cant di¡erences with time between the incubation temperatures. Lower temperatures produced longer and more di¡erentiated larvae at hatch with a smaller yolk sac. Even though some unexpected deviations were registered among batches and experimental groups, it was clear that temperature affected embryo survival and time of hatching. Overall survival was best at 6 1C, in agreement with results from earlier studies.Yolk conversion e⁄ciencies measured around the hatching point were generally high, ranging from 60% to 78%, varied between the two batches and probably re£ected the developmental variations between embryos and larvae at the respective ages (daydegrees). The hatching process was apparently an energy-demanding period; yolk conversion e⁄ciencies of unhatched embryos of similar age at each temperature were always higher. Temperature is one environmental factor that can be manipulated in hatcheries to induce hatching of viable larvae at an optimal stage of di¡erentiation with respect to ¢rst-feeding success and early survival.

Early morphological variation and induction of phenotypic plasticity in Patagonian pejerrey

“…This is consistent with the differential consumption of yolk observed in Anarhichas minor (Sund & Falk-Petersen, 2005), where decreased consumption occurred at higher temperature and thus the embryos had more yolk at hatching and were more bent over the yolk sac. Sund & Falk-Petersen (2005) and Peterson et al (2004) also observed in Anarhichas minor and Gadus morhua that embryos incubated at lower temperature hatched with larger length. Furthermore, water temperature directs the sexual differentiation process in the pejerrey Odontesthes bonariensis (Valenciennes) and affects larval condition and growth rate (Strüssmann & Patiño, 1995;Ito et al, 2005;Chalde et al, 2011).…”

“…Probably, the size of the yolk sac and the bending of the embryo after hatching will be major factors operating on the beginning of exogenous feeding (Battini et al, 1995). This is consistent with the differential consumption of yolk observed in Anarhichas minor (Sund & Falk-Petersen, 2005), where decreased consumption occurred at higher temperature and thus the embryos had more yolk at hatching and were more bent over the yolk sac. Sund & Falk-Petersen (2005) and Peterson et al (2004) also observed in Anarhichas minor and Gadus morhua that embryos incubated at lower temperature hatched with larger length.…”

Early development of the silver catfishRhamdia quelen(Quoy & Gaimard, 1824) (Pisces:Heptapteridae) from the São Francisco River Basin, Brazil

“…Furthermore, warm temperature accelerates chorion rupture (Nwosu & Holzorner 2000) and consequent hatching. However, very high temperatures can cause morphological alterations, thereby decreasing larvae survival (Sund & Falk‐Petersen 2005).…”

Ontogenesis and embryogenesis of Megaleporinus elongatus larvae (Characiformes: Anostomidae) from the Jequitinhonha River Basin

“…Higher water temperatures, within certain limits, accelerate the process of chorion rupturing and, consequently, hatching (Borçato et al, 2004;Nwosu & Holzorner, 2001). Water temperature during egg incubation has been considered important in the speed of embryonic development and survival rate (Hansen & Falk-Petersen, 2002), but very high temperatures can cause abnormalities and decreased larval survival rates (Sund & Falk-Petersen, 2005). The eggs of M. elongatus in the present study were kept in incubators with a constant water flow at 23°C with eggs hatching at 24 hr 50 min.…”