# Contribution of emerging aquatic insects to lateral transfers of Carbon and Nutrients: significance for the integrated landscape budget along a gradient of agricultural pressure

Ophélie Fovet, Benjamin Bergerot, Augustin de la Brosse, Thomas Houet, Laura Pellan, Christophe Piscart, Jean-Marc Roussel

<figure><img src="image_1.png" /></figure>

## To cite this version:

Ophélie Fovet, Benjamin Bergerot, Augustin de la Brosse, Thomas Houet, Laura Pellan, et al. Contribution of emerging aquatic insects to lateral transfers of Carbon and Nutrients: significance for the integrated landscape budget along a gradient of agricultural pressure. ARPHA Conference Abstracts, 2025, 8, pp.e149035. 10.3897/aca.8.e149035. hal-05095486

HAL Id: hal-05095486

https://hal.science/hal-05095486v1

Submitted on 3 Jun 2025

HAL is a multi-disciplinary open access archive for the deposit and dissemination of scientific research documents, whether they are published or not. The documents may come from teaching and research institutions in France or abroad, or from public or private research centers.

L'archive ouverte pluridisciplinaire HAL, est destinée au dépôt et à la diffusion de documents scientifiques de niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

<figure><img src="image_2.png" /></figure>

Distributed under a Creative Commons Attribution 4.0 International License
<figure><img src="image_3.png" /></figure>

# Contribution of emerging aquatic insects to lateral transfers of Carbon and Nutrients: significance for the integrated landscape budget along a gradient of agricultural pressure

Ophelie Fovet‡, Benjamin Bergerot§, Augustin De la Brosse¶, Thomas Houet¶, Laura Pellan§, Christophe Piscart§, Jean-Marc Roussel¶†

‡ UMR SAS, INRAE Institut Agro, Rennes, France

§ UMR ECOBIO, CNRS Université de Rennes, Rennes, France

¶ UMR LETG, CNRS Université de Rennes 2, Rennes, France

UMR DECOD, INRAE Institut Agro IFREMER, Rennes, France

Corresponding author: Ophelie Fovet (ophelie.fovet@inrae.fr)

Received: 07 Feb 2025 | Published: 28 May 2025

Citation: Fovet O, Bergerot B, De la Brosse A, Houet T, Pellan L, Piscart C, Roussel J-M (2025) Contribution of emerging aquatic insects to lateral transfers of Carbon and Nutrients: significance for the integrated landscape budget along a gradient of agricultural pressure. ARPHA Conference Abstracts 8: e149035.

https://doi.org/10.3897/aca.8.e149035

## Abstract

Biogeochemists usually consider the matter fluxes from land to streams and rivers and, no or negligible fluxes in the opposite direction. However, winged aquatic insects emerging from water bodies (e.g. lakes, ponds, perennial and ephemeral streams, wetlands) are recognized to provide nutritional subsidies to terrestrial consumers. Therefore, we hypothesized that nutrient (N, P) and carbon exports by emergent aquatic insects can be substantial to adjacent terrestrial ecosystems. Especially, we assumed these exports to increase with the density of the hydrographic network. Moreover, we advocate that the quantification of these lateral biotic fluxes of matter between terrestrial and aquatic ecosystems will improve element budgets at the landscape scale. We quantified these lateral fluxes to compare them to the input and output fluxes at the catchment scale for five sites along a gradient of agricultural intensification. The sites have different agricultural contexts and were selected within the French Long-Term
Socio-Ecological Research network of Zones Ateliers (LTSER RZA, ZA Brest Iroise, Loire and Armorique). On each site, a headwater stream and its adjacent landscape were monitored for identification and quantification of emerging aquatic insects. Quantification of the corresponding biomass (abundance and diversity) relied on trapping insects using sticky traps at different distances from their aquatic sources during the emergence season. Input and output fluxes were determined for the smallest catchment nested within the sampling site for which agricultural and water quality data were available. Landscape features, agricultural pressures, and when available data on stream water quality were compared within nested catchments. Our results showed that in catchments with higher river nutrient exports due to agricultural activities, the stream network supplies relatively high production of emerging aquatic insects, which support a feedback flux of N and C to adjacent (0 to 100 m from source) terrestrial ecosystem.

**Presenting author**

Ophelie Fovet

**Presented at**

POSTER

**Grant title**

This study is funded by the French National Research Agency (ANR) under the project STRANGE (ANR-23-CE03-0006)

**Conflicts of interest**

The authors have declared that no competing interests exist.