| SEASONAL DIFFERENCES IN MATERNAL EFFECTS ON OFFSPRING QUALITY IN THE TWO-SPOTTED GOBY (GOBIUSCULUS FLAVESCENS). |
| RODRIGUEZ-GRAŅA, L., Universidad de la Republica, 27000-Rocha, Uruguay, laurod@fcien.edu.uy; de Jong, K., Norwegian University of Science and Technology, (NTNU), NO-7491, Trondheim, Norway; Nilsson Skld, H., Gotemburg University (GU), SE-571 58, Sweden; Tiselius P (GU); Lene Friis Mller (GU); Hansen, B. Roskilde University, 260 4000-Roskilde, Denmark; Forsgren, E., Norwegian Institute for Nature Research, NO-7485 Trondheim, Norway; Amundsen, T. (NTNU) |
| Mothers determine offspring size, parental care, egg nourishment and the attributes of the offsprings father if mate choice operates. In addition, variations in mothers body size, condition and physiological state can be transmitted to the offspring influencing their development and fitness. Since reproductive effort is also affected by the environment, there is a trade- off between condition of the female, time and frequency of spawning and the offspring success along the reproductive season. This study analyses the fecundity pattern and maternal effects on offspring in Gobiusculus flavescens from Gullmarsfjord, Sweden and explores the effect of the dominant environmental conditions on its reproductive effort. We related size of females and moment of the reproductive season with proxies linked with offspring quality: number and size of eggs, egg development time, egg chemical composition (C/N ratio, HUFA) and oxidative damage (as protein carbonyls). Females were collected in April (early reproductive season; ERS) and July (late reproductive season; LRS) 2008. Analyses were performed in each first clutch spawned (2 24 hours later) and all comparisons were made by ANCOVA with female length as continuous predictor and significance considered at 5% level. Some environmental conditions differed among periods: temperature (ERS: 7,4 C 2,2 sd; LRS: 14C sd 2,1), Primary Productivity (ERS: 520,7 mg C m-2 d-1 sd 130,7; LRS: 1135 mg C m-2 d-1 sd 253,1) and presence of potential predators (hydromedusae occurred in LRS only). Potential food for adults and fish larvae was optimal during both periods but type of prey changed slightly along season. Female size affected the number of eggs spawned and the levels of protein damage in eggs. Larger female produced more eggs and small females spawned eggs with higher amount of carbonyls proteins in LRS. Reproductive period affected egg size and develop time. Largest eggs dominated in ERS and invested more time to develop and hatch than in LRS. Egg chemical composition was not affected by the period or size of the females and egg C/N ratios and HUFA content exhibited adequate levels. Gullmarsfjord seems to be an optimal place for the reproduction of G. flavescens in terms of food offer. The reproductive strategy employed by females of all sizes tended to follow a similar pattern (to produce large eggs in ERS and as many eggs as possible during the whole period). However, since small females produced eggs of potentially low quality at the end of the season, other factors like energy invested in courtship or competition for males could be playing an important effect on the condition and survivorship of the offspring. These factors should be considered in future studies. |
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