There is a need to integrate rivers into the global carbon and nitrogen cycles as rivers have the potential to a make a disproportionately large contribution to global ecosystem services. Recently we have shown that riverbeds have a very high capacity to oxidise methane and that ‘service’ is underpinned by efficient productivity of the bacterial community which carry out that methane oxidation.
In addition, in rivers, and anywhere else on Earth, the cycling of carbon is ultimately constrained by the availability of nitrogen and we have also shown that novel anaerobic parts of the N cycle appear to be tightly coupled to its aerobic parts in the well oxygenated and pristine rivers of southern England.
Ultimately these rivers are exceedingly efficient at ‘filtering out’ the potentially environmentally harmful greenhouse gas methane and the potentially toxic ammonia. What is also apparent is that these services are underpinned by incredibly high biodiversity – which we are only beginning to explore; such knowledge will be vital for us to fully understand how these systems work.
We can ask very simple questions: Does biodiversity matter for these services? Although there is probably some degree of functional redundancy; does some diversity code for something useful? We can use a combination of state-of–the-art mass spectrometry and molecular microbiology to try and establish which fraction of the diversity plays a role in delivering and sustaining these key ecosystem services.