Nutrient enrichment scarcely affects ecosystem impacts of a non‐native herbivore in a spring‐fed river

Abstract

1. Non-native invasive species (NNIS) are a global issue whose introduction into novel ecosystems can fundamentally alter nutrient recycling and storage. It is therefore important to understand factors that affect the abundance and distribution of NNIS and their effects on ecosystems. 2. We investigated how nutrient enrichment and herbivorous armoured catfish separately and in combination affect ecosystem processes in a subtropical spring-fed river (San Marcos, River, TX, U.S.A.). A replicated stream channel experiment in which nutrient enrichment was cross-classified with the presence and the absence of armoured catfish was conducted to evaluate how nutrient enrichment may affect the ecosystem and nutrient cycling effects of catfish. 3. The presence of catfish reduced periphyton biomass and altered detrital decomposition rates and, contrary to predictions, decreased periphyton N:P. In addition, the presence of catfish increased the severity of periphyton P-limitation. We found little evidence that adding nutrients altered the effects of armoured catfish on ecosystem dynamics. 4. Armoured catfish likely play an important role in the nutrient dynamics of the San Marcos River, but nutrient enrichment has little influence on determining the magnitude of ecosystem and nutrient cycling effects of this invasive and stoichiometrically unique consumer.

Nile tilapia (Oreochromis niloticus) invasions disrupt the functional patterns of fish community in a large subtropical river in China

“…Non-native species can alter the trophic position of native species and promote trophic dispersion of food webs, thereby changing ecosystem functioning (Britton, Davies, & Harrod, 2010;Cucherousset, Blanchet, & Olden, 2012) and having dramatic consequences on ecosystem processes (Matsuzaki, Sasaki, & Akasaka, 2013). For example, invasive catfish were shown to reduce periphyton biomass, alter detrital decomposition rates and change the N:P ratio in a subtropical river, the San Marcos River, Texas, USA (Datri, Pray, Zhang, & Nowlin, 2015).…”

Influence Mechanisms of Rainfall and Terrain Characteristics on Total Nitrogen Losses from Regosol

“…With control of point source contamination, nonpoint source (NPS) contamination has become dominant cause of water contamination due to its multi-source, wide distribution, the difficulty of controlling it and so on [4][5][6]. Nowadays, identifying effect factors and their mechanisms of influence on NPS pollutant exports have become research hotspots in the field of NPS pollution control [7][8][9].…”

Consumer‐driven nutrient dynamics in freshwater ecosystems: an introduction

“…In this issue, Datri et al . () and Snyder et al . () presented work addressing the synergistic effects of aquatic consumers and ambient nutrient concentrations on biogeochemical cycling.…”

“…Ambient nutrient concentrations may also influence the role organisms play in ecosystem processes (Wilson & Xenopoulos, 2011;Spooner et al, 2013). In this issue, Datri et al (2015) and Snyder et al (2015) presented work addressing the synergistic effects of aquatic consumers and ambient nutrient concentrations on biogeochemical cycling. Additionally, Boros, Talacs & Vanni (2015) examined the abiotic conditions under which consumers function as sources or sinks of elements in fresh waters.…”

“…Scientists are challenged to quantify how environmental change may affect CND in fresh waters to predict changes in ecosystem function in response to altered species abundance and diversity. Work in this special issue discusses the potential effects of water withdrawals (Atkinson & Vaughn, 2015), dam construction (Childress & Mcintyre, 2015), non-native species invasion (Datri et al, 2015) and land use change (Capps, Berven & Tiegs 2015), on CND in a variety of freshwater ecosystems. Additionally, Rantala et al (2015) explicitly addressed changes in ecosystem function after amphibian declines due to the introduction of chytrid fungus, a global conservation challenge.…”