Seasonal and spatial variations of stream insect emergence in an intensive agricultural landscape

Julien Raitif; Manuel Plantegenest; Océane Agator; C Piscart; Jean-Marc Roussel

doi:10.1016/j.scitotenv.2018.07.021

Seasonal and spatial variations of stream insect emergence in an intensive agricultural landscape

Sci Total Environ. 2018 Dec 10:644:594-601. doi: 10.1016/j.scitotenv.2018.07.021. Epub 2018 Jul 11.

Authors

Julien Raitif¹, Manuel Plantegenest², Océane Agator³, C Piscart⁴, Jean-Marc Roussel⁵

Affiliations

¹ IGEPP, Institut de Génétique, Environnement et Protection des Plantes, Agrocampus Ouest, 65 rue de Saint Brieuc, F-35042 Rennes, France; INRA, Agrocampus-Ouest, Ecology and Ecosystem Health, 65 rue de Saint-Brieuc, F-35042 Rennes, France. Electronic address: julien.raitif@inra.fr.
² IGEPP, Institut de Génétique, Environnement et Protection des Plantes, Agrocampus Ouest, 65 rue de Saint Brieuc, F-35042 Rennes, France.
³ INRA, Agrocampus-Ouest, Ecology and Ecosystem Health, 65 rue de Saint-Brieuc, F-35042 Rennes, France.
⁴ Université de Rennes 1 - UMR CNRS ECOBIO 6553, - Campus Beaulieu, 263 Av. du Général Leclerc, F-35042 Rennes Cedex, France.
⁵ INRA, Agrocampus-Ouest, Ecology and Ecosystem Health, 65 rue de Saint-Brieuc, F-35042 Rennes, France; Management of Aquatic Ecosystems in Agricultural Watersheds, INRA, Agence Française pour la Biodiversité, Rennes, France.

PMID: 29990909
DOI: 10.1016/j.scitotenv.2018.07.021

Abstract

A growing amount of literature exists on reciprocal fluxes of matter and energy between ecosystems. Aquatic subsidies of winged aquatic insects can affect terrestrial ecosystems significantly, but this issue is rarely addressed in agroecosystems. By altering the production of benthic macroinvertebrates, agricultural practices could increase or decrease the strength of aquatic subsidies and subsequently the provision of several ecosystem services to agriculture. Effects of seasons and environmental variables on aquatic insect emergence were investigated in third-order agricultural streams in northwestern France. Most emerging dry mass (DM) of caught insects belonged to Trichoptera (56%), Chironomidae (25%) and Ephemeroptera (19%). We estimated that annual emerging dry mass of aquatic insects ranged between 1445 and 7374 mg/m²/y depending on the stream. Seasonal variations were taxon-specific, with Ephemeroptera emerging only in spring, Trichoptera emerging in spring and early summer, and Chironomidae emerging throughout the year. The percentage of watershed area covered by agriculture, ammonium concentration and hypoxia positively influenced emerging DM of Chironomidae but negatively influenced Ephemeroptera. Emerging DM of Trichoptera and Ephemeroptera increased significantly as water conductivity and temperature increased. Channel openness increased the emerging DM of all taxonomic groups, but Chironomidae were more abundant in narrow, incised streams. Assuming that the biomass of aquatic invertebrates ultimately disperse toward terrestrial habitats, nutrient accumulations on land near streams were estimated to reach 0.5-2.3 kg C ha^-1 y^-1, 0.1-0.5 kg N ha^-1 y^-1 and 0.005-0.03 kg P ha^-1 y^-1, depending on the stream. This suggests a significant flux of aquatic nutrients to agroecosystems and the need for future studies of its potential influence on the ecosystem services provided to agriculture.

Keywords: Agroecosystems; Aquatic subsidies; Emergence; Environmental factors; Seasonal variations; Winged stream insects.

MeSH terms

Agriculture*
Animals
Ecosystem*
Environmental Monitoring
France
Insecta*
Rivers
Seasons