Arctic organisms with annual life cycles experience a strong selective pressure to fulfill their life cycle at low temperatures within a short seasonal window. Yet, apart from low temperature, the factors that constrain or promote growth rates in high arctic systems are still poorly understood. A substantial part of the freshwater systems in the arctic consist of shallow, fish-free ponds with the crustacean Daphnia as the key grazer. This grazer has high demands for phosphorus (P) for RNA-synthesis and subsequently protein synthesis for growth. In this study, we compared growth of juvenile Daphnia that were fed seston from two high-Arctic (79°N) ponds on Svalbard in 2004, which differed strongly in P-content and C:P-ratios. In both ponds, Daphnia growth was limited by food quantity (carbon) rather than by P or N. The study also suggests that in absence of predators, infection level of epibionts might be an important factor regulating growth rate and population development of Daphnia growth in these systems.
Van Geest, G. J., Spierenburg, P., Van Donk, E., & Hessen, D. O. (2007). Daphnia growth rates in Arctic ponds: limitation by nutrients or carbon? Polar Biology, 30(2), 235-242. https://doi.org/10.1007/s00300-006-0177-7