2026 Summer Field Work – Free Flow Lab Internships

Electrofishing sampling

Getting close to the end of this summer field work season! With still some more barrier impacts assessments and river walkovers to go, the bulk of field work for this season has been sucessfully completed thanks to the help of four biology students from the University of Vigo that have worked with us during their research internship.

A big thanks to:

Yago Pérez González
Beatriz González González
Xabier Martín Lois
Martín Justo Santiago

Barrier Impact Assessments

Bridge footing with small head drop but dry crest.

A two-piped culvert with a major perched drop at outlet.

A culvert with a small perched outlet.

A bridge footing ramp with a major and steep drop.

Recurrent bridge footing ramps.

4-piped culvert.

Above are some of the low-head barriers that we have been sampling. Our objective is to estimate the impact of these structures on river connectivity. More specifically, we are looking at the discontinuities these barriers are causing in the stream hidrogeomorphology and macroinvertebrate and fish communities.

A european eel (Anguilla anguilla) being weighted

Electrofishing gear

Fish handling

A brown trout (Salmo trutta) being measured

On-site coarse macroinvertebrate community assessment

In-lab fine macroinvertebrate community assessment.

Macroinvetebrates book with dichotomous keys.

Bea looking at a macroinvetebrate sample

Yago identifying macroinvetebrates

Although small and apparently insignificant, some of these barriers are severly fragmenting rivers, modifying the stream geomorphology, modifying habitats and posing major obstacles to fish movement.

A clogged culvert, obsolete and abandoned. Culvert clogging causes hydraulic malfunctioning and a poses a barrier to fish movement.

Gravel was painted and tracked to measure sediment transport

River walkovers

Barrier inventories are incomplete and data on lateral barriers is especially scarce. With river walkovers, we are recording longitudinal and lateral barriers to improve the completeness of barrier databases, model barrier occurrence and adapt the restoration of river connectivity to incomplete data.