Food niches of planktonic rotifers: Diversification and implications

Abstract

AbstractThe diverse diets of common planktonic rotifers are described in detail from field and laboratory observations and experiments. Also considered are methodological approaches, rotifer feeding mechanisms, and the availability in natural waters of less well‐known food items (detritus, picoplankton, protozoans). Despite much variation among and within rotifer genera, food niches of planktonic rotifers can be subdivided into four broad, overlapping categories defined by the predominant types and sizes of food ingested: (1) microphagous rotifers that eat fine detritus/organic aggregates, picoplankton, and 2–10 μm nanoplankton; (2) polyphagous rotifers that eat the above items, larger nanoplankton, and small (20–50 μm) microplankton; (3) macrophagous algivores that eat 5–50 μm algae; and (4) macrophagous omnivores/predators that eat 5–250 μm algae, protozoans, and metazoans. These diet‐based categories have ecological advantages over categories based on rotifer morphology or feeding mode. The information on diets assembled here is important for understanding: (1) the population dynamics of planktonic rotifers and their food organisms; (2) the position of rotifers in classical and microbial food webs; (3) the seasonality, spatial distribution, and species diversity of rotifers in plankton communities; and (4) food overlap, and thus potential resource competition, among planktonic protozoans, rotifers, and crustaceans.