Overcrowding,food and phosphorus limitation effects on ephipphia production and population dynamics in the invasive species Daphnia lumholtzi

Daphnia lumholtzi has been very successful in colonizing North America since its appearance in Texas in 1990. Although previous studies have sought to link its success as an invasive species with various aspects of its population biology, there is little experimental data linking the invasion success of D. lumholtzi with its autecology, specifically its reproduction strategy. In this study we sought to link food quality and quantity to diapause in D. lumholtzi through a variation in phosphorus (P) content of algae, food quantity, and light level. We also assessed the effect of Daphnia peak population densities on reproductive rates and production of resting eggs. We found that when food is abundant, per capita ephippia production may be limited by P, but under food limitation conditions, there is no significant effect of food quality on ephippia production. Our results suggest that a combination of food quality/quantity and population density may work together to induce the production of resting eggs in this invasive species. Handling editor: S. Declerk