Daphnia fed algal food grown at elevated temperature have reduced fitness

• Main Authors: Anna B. Sikora, Piotr Dawidowicz, Eric von Elert
• Format: Article
• Language: English
• Published: PAGEPress Publications 2014-05-01
• Series: Journal of Limnology
• Subjects: Temperature, food quality, Daphnia, body size, Scenedesmus obliquus, life history.
• Online Access: http://www.jlimnol.it/index.php/jlimnol/article/view/898

<p>Lake water temperature is negatively correlated with fatty acids content and P:C ratio in green algae. Hence, elevated temperature may indirectly reduce the fitness of <em>Daphnia</em> due to induced decrease in algal food quality. The aim of this study was to test the hypotheses that quality of algal food decreases with increasing temperature of its culture and that large-bodied <em>Daphnia </em>are more vulnerable to the temperature-related deterioration of algal food quality than small-bodied ones. Laboratory life-table experiments were performed at 20°C with large-bodied <em>D. pulicaria</em> and small-bodied <em>D. cucullata</em> fed with the green alga <em>Scenedesmus obliquus</em>, that had been grown at temperatures of 16, 24 or 32°C. The somatic growth rates of both species decreased significantly with increasing algal culture temperature and this effect was more pronounced in <em>D. pulicaria </em>than in <em>D. cucullata. </em>In the former species, age at first reproduction significantly increased and clutch size significantly decreased with increasing temperature of algae growth, while no significant changes in these two parameters were observed in the latter species. The proportion of egg-bearing females decreased with increasing algal culture temperature in both species. The results of this study support the notion that the quality of algal food decreases with increasing water temperature and also suggest that small-bodied <em>Daphnia</em> species might be less vulnerable to temperature-related decreases in algal food quality than large-bodied ones.</p>