The waterscape as a framework for species coexistence: diatoms as model

The waterscape is defined as the spatially and temporally dynamic water present on and within the uppermost layer of the Earth, which serves as the interface between the lithosphere, atmosphere, hydrosphere, and biosphere—known as the critical zone. The WATERSCAPE project aims to elucidate how waterscapes contribute to the coexistence of aquatic species.

Diatoms will serve as our model organisms, and the high-mountain waterscape—where theoretical expectations can be empirically tested—will be our model system. Specifically, we aim to demonstrate that the spatial and temporal variability of waterscapes facilitates diatom species coexistence by either equalizing relative fitness or promoting niche differentiation. The project will integrate field observations, field experiments, and laboratory experiments to characterize the growth responses of a large number of diatom species (hundreds) to environmental gradients. Ultimately, this approach will allow us to fit parameters of coexistence theory and investigate the role of different spatial and temporal environmental fluctuations in shaping species distribution patterns across the high-mountain waterscape

The project will consider multiple waterscape scales. At the range scale, the entire Pyrenean lake district will be analyzed, focusing on how landscape characteristics influence aquatic microhabitats. Specifically, we will examine epilithic diatom communities. The research team has collected approximately 500 lake samples across the entire range, enabling us to assess whether dispersal and stochastic processes predominate over biotic interactions and to determine the extent to which topography and landscape spatial properties influence these dynamics.

At the catchment scale, the waterscape will be characterized with high precision, incorporating both extensive surveys and field experiments using artificial substrates to study diatom microhabitats comprehensively. The Sant Nicolau Valley, located in Aigüestortes i Estany de Sant Maurici National Park, has been selected for this study due to the availability of previous data and field instrumentation.

Finally, the project will investigate the proximal environment of diatoms and their species autoecology through single-species cultures. Laboratory experiments will be conducted to characterize their relative fitness and niche differentiation across key environmental gradients. This fundamental information will provide critical feedback for interpreting the patterns observed at the broader waterscape scales.

By integrating empirical and theoretical approaches, the project aims to make significant contributions to species coexistence theory, enhancing our understanding of the interactions between environmental variability and biodiversity patterns.

 

Duration: September 2023 - August 2027

Funding Agency: Ministerio de Ciencia e Innovación

LOOP participants: Jordi Catalan, Marisol Felip, Lluís Camarero

Coordinators : Jordi Catalan, Marisol Felip

Collaborators: Meritxell Batalla, Daniel Martin, Sergi Pla, Elena Fagin, Daniel Martín, Saul Blanco, Carlos Rivera-Rondón, Jordi Martínez Artero

Participant institutions: CREAF, University of Barcelona, CEAB-CSIC