The role of ecosystem engineer species in habitat restoration

This project is studying the role of a migratory fish species, the sea lamprey, on sediment mobility and river morphology in its breeding grounds. Understanding the role of this species is important for monitoring the restoration and renaturation of the Selune valley once continuity has been restored and major migratory species have returned.

The role of ecosystem engineer species (sea lamprey) in sedimentary processes and the restoration of aquatic habitats

Coordinator(s)

Anne-Julia Rollet and Emilien Lasne

Scientific context

5_IllusTxt_EspIngé-3 — Lamprey spawning ground in the downstream zone of the Sélune - credit: P.Vrchovsky © Paul Vrchovsky

The aim of removing the dams on the Selune is to restore ecological continuity and aquatic and riparian ecosystems in the catchment area. One of the conditions for the success of the operation is the reappearance of river forms and diversified aquatic habitats. Ideally, the watercourse would return to its original course and dynamics, but the need to manage sediments has involved human intervention of varying degrees depending on the sector, with probable consequences for the morphology of the watercourse (sinuosity, geometry) and the nature of the bed substrate (granulometry).

The sea lamprey, a candidate for recolonisation, shapes the substrate of watercourses by building nests where it lays and covers its eggs. This activity can significantly and sustainably modify the distribution of sediments in breeding areas and increase the complexity of aquatic habitats. The reopening of the upstream section of the Selune to migratory fish provides a unique opportunity to characterise the fish-geomorphology relationship, and to clarify the role of these species as an ecosystem engineer and their contribution to the restauration of the Selune.

5_IllusTxt_espIngé — The role of the lamprey as an ecosystem engineer during the breeding season - credits: P.Vrchovsky © Paul Vrchovsky

Subject(s) of study

The project focuses on a migratory species that plays an important role in sedimentary processes and river morphology: the sea lamprey.

Objectives

The project aims at:

Identifying and characterising potential breeding habitats in the restaured sections and their quality for sea lampreys.
Characterise the role of this species in morphogenic processes and sediment flows.

Methods

Protocols specific to fluvial geomorphology (sediment tracing using passive transponders, granulometry, measurements of speeds and channel geometry) and to monitoring fish reproduction (location and abundance of nests) will be implemented at several sites:

Downstream of the dams, by comparing the frequencies of movement and migration distances of sediment tracers according to whether or not they are mobilised during spawning,
In the former reservoir of the dams in order to identify and characterise potential spawning sites, assess the morphological resilience of the channel and then monitor potential spawning areas and their impact on coarse sediment dynamics after the dams have been removed.

5_IllusTxt_espIngé-2 — Methods used in the project on the role of engineer species: sediment tracers PIT-TAGs, topographic surveys - Credits: P.Vrchovsky © Paul Vrchovsky

Laboratories involved

Department of Geography and Spatial Planning, UFR Social Sciences, Université Rennes 2
LETG - UMR Coastline Environment Remote sensing Geomatics, Rennes
DECOD - UMR Ecosystem Dynamics and Sustainability: from source to ocean, INRAE/Institut Agro/Ifremer, Rennes

Cookie type	Means of blocking
Analytical and performance cookies	Realytics Google Analytics Spoteffects Optimizely
Targeted advertising cookies	DoubleClick Mediarithmics

Mandatory cookies	Functional cookies	Social media and advertising cookies
These cookies are needed to ensure the proper functioning of the site and cannot be disabled. They help ensure a secure connection and the basic availability of our website.	These cookies allow us to analyse site use in order to measure and optimise performance. They allow us to store your sign-in information and display the different components of our website in a more coherent way.	These cookies are used by advertising agencies such as Google and by social media sites such as LinkedIn and Facebook. Among other things, they allow pages to be shared on social media, the posting of comments, and the publication (on our site or elsewhere) of ads that reflect your centres of interest.
Our EZPublish content management system (CMS) uses CAS and PHP session cookies and the New Relic cookie for monitoring purposes (IP, response times). These cookies are deleted at the end of the browsing session (when you log off or close your browser window)	Our EZPublish content management system (CMS) uses the XiTi cookie to measure traffic. Our service provider is AT Internet. This company stores data (IPs, date and time of access, length of the visit and pages viewed) for six months	Our EZPublish content management system (CMS) does not use this type of cookie.