An eye in the sky: using drone technology to monitor freshwaters

Aeryon Scout drone, increasingly used for mapping global environments. Image: Wikipedia

Developments in unmanned aerial vehicle (UAV) technology are providing new, potentially cost-effective opportunities for ecologists and conservationists to monitor and protect ecosystems, particularly in remote areas.  Widely known for their (often debated) use in remote warfare, there is increasing consensus that drones – as UAVs are often known – have the potential to be used for more positive goals, giving new high-tech means of understanding and potentially protecting global environments.

Lian Pin Koh outlined the potential of drones for conservation in a 2013 TED talk, arguing that they provide an affordable means of mapping biodiversity at higher resolution than current satellite remote sensing technologies; and that they are useful for monitoring protected areas for threats such as poaching and deforestation.  Three journal articles – by Koh and Serge Wich in 2012, Karen Anderson and Kevin J Gaston in 2013 and Richard Schiffman in 2014 – suggest similar potential.

In 2012, Koh and Wich founded an organisation called Conservation Drones to help bring together available information on the use of drones for remote sensing.  As this UNEP article describes, whilst the technology is still developing, there is a huge amount of ongoing public and private investment in UAVs, which is likely to address current limitations such as limited flight time, and to continue to bring production costs down.

As yet, there has been little research on the potential of drone technology for monitoring freshwater ecosystems.  However, a new journal article “The potential of remote sensing in ecological status assessment of coloured lakes using aquatic plants“ by MARS scientist Sebastian Birk and Frauke Ecke addresses this shortfall.  Their paper explores the potential of drones for monitoring the health of remote Swedish lakes which are heavily coloured by dissolved carbon.   Birk and Ecke found that it is possible to assess the ecological health of coloured lake ecosystems by monitoring plant vegetation which is detectable by drones.  Their findings have the potential to significantly alter how ecological monitoring in lakes is carried out, particularly in remote and inaccessible areas.

Lake in northern Sweden. Image: Thomas Hellberg | Flickr under Creative Commons

The growth and diversity of aquatic plants is an important indicator for understanding the health and functioning of freshwater lakes.  However, it’s very expensive and time-consuming for scientists to sample and map aquatic plants manually, particularly given that there are thousands of lakes in remote areas of Sweden.  Birk and Ecke’s article outlines how developments in drone technology allow the mapping of aquatic plants at a 5cm scale, which means that plants can potentially be identified to species level at a quarter of the cost of manual surveys.  This high image resolution – higher than previously possible using satellite remote sensing – potentially allows for more detailed remote monitoring of lakes.

Sebastian Birk describes the forward-thinking focus of this study:

“Drones give an opportunity to economically monitor the effects of anthropogenic stress to the myriad of lakes in the boreal zone. Field sampling is a costly exercise involving at least two surveyors snorkeling or sitting in a boat. And even then, you have to reduce your efforts to selected transects, not covering the entire lake. Using the drone is much easier, provided that the pictures taken by the drone are processed automatically, which is not yet possible.”

A large proportion of global lakes – especially those in boreal and tropical environments – are ‘coloured’ due to dissolved solutes in the water (especially organic carbon).  Aquatic plants in coloured lakes mostly have floating or emergent (i.e. partially above the surface) leaves, which allow their photosynthetic tissues (those that create energy for the plant from sunlight) are exposed to the sun above the murky water.

Birk and Ecke studied 72 cloudy Swedish lakes to assess the potential of using emergent and floating plant species which can be detected by  drones as proxies for predicting the ecological status of the lake in which they live.  This process found strong correlations between the potential of drone-detectable species and those which are undetected, suggesting that remote sensing by drones could provide accurate assessments of the overall vegetation and health of coloured lakes.

Sebastian Birk outlines the potentially wide-ranging impacts of drones on freshwater monitoring:

“In an era of global austerity economic solutions tackling environmental issues are in demand. Our study demonstrates that drones offer useful services in ecosystem monitoring and assessment. Water management, in particular, requires extensive data that drones acquire most cost-effective. This could bring this technique from specialist application (e.g. real-time ecological research missions) into regular field survey: instead of boat and rubberboots, the surveyor now packs airplane and remote control.”

The next stage, of course, will be to put these ideas into practice by flying experimental drones over freshwater ecosystems.  How long before every University research department has its own fleet of ‘eco-drones’?  What legal and ethical issues will scientific researchers encounter with drone monitoring?  Will the technology usher in a new era of ‘fortress’ conservation where drones are used to remotely monitor wildlife – and potentially people – in national parks and other protected areas?   Or are drones simply more accurate, more affordable versions of existing satellite remote sensing technology, which is widely – and largely uncontroversially – used already?