Annual variation in energy reserves in male three‐spined stickleback, Gasterosteus aculeatm L. (Pisces, Gasterosteidae)

Abstract

Wet and dry weights of tissue were measured and concentrations of glycogen, lipid and protein were estimated for the liver, gonad and carcass of male sticklebacks from an annual population collected each month over one complete year. In young-of-the-year there is one period of rapid weight gain, in all three body regions (liver, carcass and gonads) but particularly of the carcass, in the autumn and a second in spring and early summer. This is accompanied by an increase in the water content of all three body regions. The gonadosomatic index also increases sharply in spring and early summer. Young sticklebacks accumulate lipid and glycogen slowly during the autumn and winter of their first year of life and more rapidly from late winter to early summer. Thus, the period of most rapid accumulation of these reserves coincides with the time when body weight and gonad maturation are also increasing sharply. Lipid and glycogen levels fall during the reproductive season in those males that breed? so that by July they are reduced to 43% and 37% (respectively) of their peak values in May. Levels of protein increase throughout the year as the fish grow, but in breeding males by July the concentration of protein in the carcass falls to 70% of pre-breeding levels. Breeding males therefore reach the end of the reproductive season with their total energy reserves severely reduced, and consequently they suffer a very high mortality. In contrast, adult males that fail to reproduce survive beyond the breeding season. They continue to gain weight and to accumulate lipid and glycogen from August to September, but these. energy reserves fall (to levels comparable to those of post-breeding fish) in December, when these fish probably die. These results demonstrate that in male sticklebacks, growth and gonad maturation can be sustained in parallel with the accumulation of energy reserves, which are subsequently extensively depleted as a result of reproductive activities.

Effects of sewage effluent remediation on body size, somatic RNA: DNA ratio, and markers of chemical exposure in three-spined sticklebacks

“…These observations are consistent with previous reports of the age structure (Mann, 1971;Allen and Wootton, 1982;O'Hara and Penczak, 1987;Wootton and Smith, 2000;Poizat et al, 2002;Wootton, 2007) and sex ratio (Kynard, 1978;Wootton, 1984;Mori, 1993;Arnold et al, 2003) of three-spined stickleback populations. Disproportionate mortality among males due to the energetic demands and risks associated with male parental investment has been suggested to account for the female bias (Chellappa et al, 1989;Arnold et al, 2003).…”

Carotenoids, oxidative stress and female mating preference for longer lived males

“…Males build a nest in which a female will deposit all her eggs, and all subsequent parental care (including intensive fanning of the eggs and guarding of the nest and fry) is by the male. Both sexes might participate in several breeding attempts within a single breeding season, but reproduction is costly, and in annual populations most fish senesce and die before the end of the season (Chellappa et al 1989;Poizat et al 1999). Reproductive effort in each breeding attempt is influenced by this short-life expectancy, with individuals of both sexes investing more in reproduction as future reproductive opportunities decline (Candolin 1998;Poizat et al 1999).…”

“…Reproductive effort in each breeding attempt is influenced by this short-life expectancy, with individuals of both sexes investing more in reproduction as future reproductive opportunities decline (Candolin 1998;Poizat et al 1999). For males in particular, reproductive activities are energetically expensive (Chellappa et al 1989;Fitzgerald et al 1989) and males in poor condition may die during the parental phase and thus fail to rear the offspring to independence or they may eat the eggs in their nest in order to improve their physical condition ( Whoriskey & FitzGerald 1994). Given this breeding system and the rapid rate of senescence, there should be selection pressure on females to choose males who are capable of remaining alive and healthy for the duration of parental care.…”

Sex differences in resource utilization by the peacock blenny

“…For males that care and guard the eggs, one of the likely features of male reproductive investment is a reduction of feeding opportunities during the breeding season (e.g. Qasim, 1957;Miller, 1984;Sargent & Gross, 1986;Santos & Almada, 1988;Chellappa et al, 1989;Almada et al, 1992;Santos, 1992;Smith & Wootton, 1995;Santos et al, 1996).…”