Predation by an omnivorous fish and food availability alter zooplankton functional diversity: a microcosm approach

Abstract

Studies considering the functional traits of organisms, populations, and communities functional indices increase the understanding of many factors on ecosystem functioning. Here, we analyze the predation effect (by fi sh) on zooplankton functional diversity and the effects of biomass and density of periphytic algae on zooplankton feeding type trait and body size. We expect that intense predation by fi sh on zooplankton leads to higher values of zooplankton functional diversity and that food resource will be positively related to the abundance of zooplankton trait and body size.For that, microcosms were established (T1-fi sh-absence, and T2-fi sh-presence, both with periphytic algae as food). We observed that fi sh presence decreased zooplankton functional diversity through modifi cations in the availability of nutrients and algae, through the middle-out effect. We also observed that body size had a negative relationship with the food resource, reaffi rming that high food availability in subtropical lakes is linked to small-bodied zooplankton. The raptorial copepods covariate positively with the periphytic algae, which was an alternative food resource and, in this case, the main form of carbon input into the system. In this study, omnivorous fi sh reduced zooplankton functional traits, which can alter the energy stock and energy fl ow in aquatic ecosystems.

Alternance of alternative stable states influence the functional diversity of microcrustaceans in a shallow subtropical lake

“…Thus, understanding the structure and functional diversity of microcrustaceans through functional traits, allows us to understand the functioning of aquatic environments (Amaral et al . 2021).…”

“…These are defined as traits that involve the fitness of organisms, and are classified into morphological, life history, behavioural and physiological traits (Sodr e & Bozelli 2019). Thus, understanding the structure and functional diversity of microcrustaceans through functional traits, allows us to understand the functioning of aquatic environments (Amaral et al 2021).…”