Intraspecific selectivity, compensatory feeding and flexible homeostasis in the phagotrophic flagellate Oxyrrhis marina: three ways to handle food quality fluctuations

Abstract

The phagotrophic flagellate Oxyrrhis marina shows a strong stoichiometric plasticity when fed differently grown Rhodomonas salina. We tested whether differently pre-conditioned O. marina displayed selective feeding behaviour from a mixture of nitrogen and phosphorus depleted R. salina. We observed selective feeding of O. marina, always selecting phosphorus rich R. salina independent of the pre-conditioning of the protists. In a second experiment, O. marina was again pre-conditioned either with nitrogen-or phosphorus-depleted R. salina and was refed with either of the differently limited R. salina in single food treatments (not in a mixture). The phagotrophic flagellate displayed compensatory feeding which means that O. marina feed more on the food source which they were not given before. Due to its stoichiometric plasticity, O. marina might handle bad quality food by following the stoichiometry of its prey and additionally by active selective feeding towards P-rich algae to enhance growth. Post-ingestion selection might as well be an important feature which means that ingested elements in excess are quickly excreted and scarce elements are ingested through accelerated food uptake.

Microzooplankton Stoichiometric Plasticity Inferred from Modeling Mesocosm Experiments in the Peruvian Upwelling Region

“…In Meunier et al (2012b) selection experiments, the microzooplankton P:C ratio was also higher when the phytoplankton N:C ratio was lower and vice versa (their Table 4). We thus hypothesize that microzooplankton adjust their internal P:C ratio in response to food quality in terms of prey N:C ratio.…”

From Elements to Function: Toward Unifying Ecological Stoichiometry and Trait-Based Ecology

“…Grazers however possess a large range of adaptations that allow them to minimize the consequences of these nutrient imbalances. Besides selective feeding (e.g., Kagata and Ohgushi, 2011;Meunier et al, 2012Meunier et al, , 2016a and habitat choice (Winder et al, 2004;Reichwaldt, 2008), consumers may handle poor food quality by selectively retaining and excreting nutrients (Elser and Urabe, 1999;Knoll et al, 2009). These physiological adjustments are tightly linked with the stoichiometry of traits such as elemental ratios of recycled materials and body stoichiometric homeostasis.…”

“…The recognition of the importance of stoichiometric constraints between consumer needs and prey nutrient content has substantially increased our understanding of trophic interactions. For example, high C:P food is often of low-quality for a variety of organisms including molluscs (Stelzer and Lamberti, 2002;Fink and Elert, 2006), crustaceans (Boersma and Kreutzer, 2002;Meunier et al, 2012Meunier et al, , 2016a, insects (Perkins et al, 2004), fish (Borlongan and Satoh, 2001;Vrede et al, 2011), and birds (Grone et al, 1995). ES has therefore proven to be a highly suitable framework in community ecology, explaining consumer responses to prey food quality (food intake, growth, as well as competition between consumer species, and consumer effects on prey nutrient composition (Sterner, 1990;Sterner et al, 1992;Sterner and Hessen, 1994).…”

Prey C:P ratio and phosphorus recycling by a planktivorous fish: advantages of fish selection towards pelagic cladocerans

“…; Meunier et al. ). Different groups and species of zooplankton differ significantly in their average nutrient ratios (Andersen & Hessen ; Laspoumaderes et al.…”