Phosphorus limitation in Daphnia: Evidence from a long term study of three hypereutrophic Dutch lakes

Abstract

The Loosdrecht lakes comprise three shallow, interconnected hypereutrophic lakes in The Netherlands. A lake restoration project conducted during the 1980s resulted in reduced phosphorus loading. However, no changes in phytoplankton abundance or species composition were noted, although seston carbon:phosphorus (C:P) ratios increased. Filamentous cyanobacteria and detritus continued to dominate the seston. Moreover, planktivorous fish were very abundant. Relationships between zooplankton abundance and seston abundance and stoichiometry (C:P and carbon:nitrogen ratios) were analyzed using data collected during 9 yr of intensive study of the three lakes. Analysis based on annual means shows surprisingly strong and consistent inverse relationships between Daphnia abundance and the seston C:P ratio for two of the three lakes. In these two lakes (Loosdrecht and Vuntus Lakes), the annual mean abundance of Daphnia cucullata ranged from 104 to 0.7 individuals L−1 over a range in mean seston C:P ratios from about 250 to 500 (molar). In the third lake, Breukeleveen, Daphnia abundance was higher for a given seston C:P ratio, especially during the 2 yr following a biomanipulation project in this lake. Analysis of seston C:P ratios and Daphnia abundance in individual samples provides further evidence that high seston C:P ratios constrained Daphnia abundance in all three lakes. In contrast to Daphnia, the abundances of zooplankters with low P requirements, including Bosmina spp. and cyclopoid copepods, show little relationship to seston C:P ratios. These results suggests that the abundance of Daphnia in the Loosdrecht lakes was determined by the variable P content of their diets and consistently strong fish predation.

The influence of phosphorus concentration on the population dynamics and resting egg formation of two cladocerans

“…In P-limited Canadian Shield lakes, the population growth of Daphnia was inhibited by the P-limited food (Makino et al 2002). The same results occurred in several Dutch lakes (DeMott & Gulati 1999). In this study, P concentration had significant effects on the population density of M. irrasa and D. similoides (p < 0.05).…”

Phytoplankton contribution to sestonic mass and elemental ratios in lakes: Implications for zooplankton nutrition

“…It is also convincingly demonstrated that a key determinant of C : P ratio in phytoplankton is the balance of light and nutrients (Urabe and Sterner 1996;Hessen et al 2002), where high light and low P cause elevated C : P and vice versa. The same pattern is reflected in lakes, however Urabe et al 2002), and the growth rate of Daphnia in these studies, yet facing a mixed sestonic diet, was closely correlated with sestonic C : P. The potential dependence of Daphnia growth rate and seston stoichiometry has been demonstrated in other studies as well (DeMott and Gulati 1999), yet the role of other food quality parameters, such as essential fatty acids, will add to this knowledge (cf. Brett et al 2000;Boersma et al 2001).…”

“…Laboratory studies have indicated a C : P threshold of food of approximately 300, above which Daphnia faces direct P-limitation (i.e., where C-based growth efficiency will decrease [Sterner 1993;DeMott et al 1998;Boersma 2000]). It is also convincingly demonstrated that a key determinant of C : P ratio in phytoplankton is the balance of light and nutrients (Urabe and Sterner 1996;Hessen et al 2002), where high light and low P cause elevated C : P and vice versa.…”

“…This point could also illustrate how different inferences of potential P-limitation in Daphnia may result, depending on the actual threshold value that is chosen. If applying a lower estimate for onset of P-limitation in Daphnia (C : P ϭ 90; DeMott et al 1998), most lakes should pose constraints on C-use efficiency for Daphnia as a result of P-limitation. On the contrary, only few lakes would have any risk of P-limitation if applying an upper bound for onset of P-limitation (C : P ϭ 320; Urabe et al 1997).…”

“…During the past decade, it has become increasingly clear that not only food quantity in terms of carbon (C) mass of edible algae or quality in terms of digestibility or toxicity (Lampert 1977) but also the food quality in terms of specific content of key elements (Hessen 1992;Sterner 1993;DeMott et al 1998) or biomolecules (Ahlgren et al 1990;Müller-Navarra 1995) may be a main determinant of zooplankton growth. These aspects have been elaborated upon particularly for freshwater systems, but studies from a wide range of ecosystems indicate that food quality limitations may pose a general constraint on energy transfer in a variety of food webs (Elser et al 2000a,b).…”