Post provided by Chloe Robinson
The demands of a growing human population are putting increasing pressure on the Earth’s natural systems and services. Dubbed the ‘Anthropocene’, we are currently living in a period where human actions are directly altering many earth processes, including atmospheric, geologic, hydrologic and biospheric processes. Climatic change and the resulting consequences, including rising temperatures, changing precipitation (i.e. rainfall, snow etc) and increase in frequency of storm events, represent the biggest challenge to our future and the life-support ecosystems that make our world habitable.
In 1970, Earth Day was launched as a modern environmental movement and a unified response to an environment in crisis. Earth Day has provided a platform for action, resulting in the creation of the Environmental Protection Agency (EPA), The Clean Air, Clean Water and Endangered Species Acts in the US and more globally. This year, 22 April marks the 50th anniversary of Earth Day, and the number one environmental crisis theme which needs immediate attention is ‘Climate Action’. Many of our ecosystems on earth are degrading at an alarming pace and we are currently experiencing a species loss at a rate of tens or hundreds of times faster than in the past.
In a world where we are predicted to lose 1 million species by 2050, being able to monitor the existing biodiversity and track trends of ecosystem change and species abundance is vitally important for determining the climate action required to prevent these losses. In this blog, I’m going to explore how we’re currently monitoring systems and biodiversity across the globe, from the skies to on the ground, to better understand the health and resilience of ecosystems.
Methods of Monitoring: Remote Sensing
Remote sensing is a method of acquiring information about the Earth’s surface without actually being in contact with it. Due to the ability of remote sensing to scan very large areas, many remote and formerly inaccessible regions are now able to be monitored. This has therefore enabled the assessment of natural resource distribution and habitat condition for a variety of ecosystems.
A recent special feature on remote sensing in Methods in Ecology and Evolution, highlighted studies that have demonstrated how remote sensing and satellite imagery can be used to improve the monitoring of biodiversity.
One case study in this issue, by Duncan et al., featured the application of remote sensing to monitor the resilience of mangrove forest resilience and resistance to sea level rise. Mangroves provide key ecosystem services for climate change mitigation and adaptation. Our ability to monitor them using remote sensing is important to inform conservation and management priority assessments, particularly in data‐deficient regions. Within this study, the authors describe how they were able to see low sea-level rise resilience and high degrees of variation regarding resistance and resilience capabilities within their sites.
Another study from the special feature, this one by Pasetto et al., described the integration of satellite remote sensing data with ecosystem modelling at local scales. They use this method to quantify the interaction among the vegetation component and the hydrological, energy and nutrient cycles of ecosystems. The review encouraged the further use of satellite remote sensing for ecosystem modelling. It also suggested recommendations for improving the quality of data collected using remote sensing technologies.
It’s clear that remote sensing can provide critical ecological information; however, this technology is most effective when used in conjunction with other biological monitoring techniques. A study by Lausch et al. (2018), determined that out of the approaches used, there’s no single approach that is sufficient to monitor the complexity and multidimensionality of vegetation health over the short to long term and on local to global scales. The authors concluded by stressing the need for standardised approaches for assessing vegetation health, regardless of the methodology used.
Methods of Monitoring: Camera Traps and Acoustics
Coming back down to earth from remote sensing, camera traps and acoustic monitors (or a combination of both), have proven to be effective methods for observing and quantifying changes in ecosystems and species presence. It’s difficult to understand the spatial and temporal (time) distribution of flying insects, particularly of insect species which form short-term swarms. A recent Methods in Ecology and Evolution article by Ruczyński et al., described the use of novel camera transects to measure spatio‐temporal fluctuations in the abundance of nocturnal flying insects within different habitats. Hinke et al. highlighted the difficulty of collecting spatially extensive data on reproductive success of penguins. The authors explained in this study, how time-lapse cameras enabled collection of highly accurate and minimally invasive data collection in a remote location.
For monitoring biodiversity in the seas and in the air, it’s often most effective to use acoustic devices. A research article from 2018 describes how passive acoustic monitoring devices can be used for dolphin species to estimate absolute density and abundance. In that article, Nuuttila et al. demonstrated how, by using a Generalised Additive Model, you can estimate the effective detection radius of an acoustic device, which lets you estimate where an individual dolphin is located.
Another study in Methods in Ecology and Evolution showcased the use of modern machine learning to detect birds acoustically. The authors – Stowell et al. – highlighted how gaining data on the abundance of birds is important for monitoring specific species as well as overall ecosystem health. This study found that machine learning and general‐purpose acoustic bird detection can generate useful data without the need for manual re-calibration of pre-training of the detector.
Methods of Monitoring: DNA-Based Approaches
In addition to monitoring biodiversity directly, using methods mentioned above, we can also monitor biodiversity passively by the traces they leave in their environment. Through monitoring the presence or absence of DNA from particular groups of species, such as marine megafauna or soil-dwelling nematodes, we can make assumptions as to the health status of an ecosystem. In a recent Practical Tools article, Truelove et al. described how environmental DNA (eDNA) collected from seawater can be used as an effective tool for detecting an elusive and ecologically important marine species, the white shark. The authors highlight how it is possible to detect this species within 48 hours by directly analysing the DNA onboard the research vessel. eDNA is known to be a rapid and accurate method of obtaining biodiversity information, particularly for DNA metabarcoding-based approaches. Geisen et al. described how high-throughput sequencing of soil samples is the most cost‐effective, in‐depth technique available to study soil nematode community responses to changes in the environment. Their study found that both sample location and association plant species affected relative abundances of bacterivorous nematodes.
Depending on the type of system and target species, there are many methods of monitoring the health of the Earth’s ecosystems and the biodiversity which inhabit them. Further development and optimisation of current methods and innovations of new biological monitoring techniques are required to gather as much knowledge as possible on the current status of the Earth’s vital systems. We need to understand how these systems as a whole respond to change to instigate the most appropriate climate action. There’s so much you can do to help protect and restore our planet; check out the map on the Earth Day 2020 website to find a digital Earth Day event close to you.
To read more about the remote sensing papers featured in this blog, check out the Methods in Ecology and Evolution special feature, ‘Improving biodiversity monitoring using satellite remote sensing’.
To find out more about how camera traps are used to monitor insects, check out the Methods in Ecology and Evolution article, ‘Camera transects as a method to monitor high temporal and spatial ephemerality of flying nocturnal insects’.
To discover more about the use of time-lapse images to estimate penguin reproductive success, check out the Methods in Ecology and Evolution article, ‘Estimating nest‐level phenology and reproductive success of colonial seabirds using time‐lapse cameras’.
To read more about how acoustic devices are being used to detect and estimate locations of dolphins, check out the Methods in Ecology and Evolution article, ‘Estimating effective detection area of static passive acoustic data loggers from playback experiments with cetacean vocalisations’.
To find out more about how machine learning is being used to acoustically detect birds, check out the Methods in Ecology and Evolution article, ‘Automatic acoustic detection of birds through deep learning: The first Bird Audio Detection challenge’.
To discover more about the use of environmental DNA to detect sharks, check out the Methods in Ecology and Evolution article, ‘A rapid environmental DNA method for detecting white sharks in the open ocean’.
To find out more about how high-throughput DNA sequencing is being used to detect presence of nematode communities, check out the Methods in Ecology and Evolution article, ‘Integrating quantitative morphological and qualitative molecular methods to analyse soil nematode community responses to plant range expansion’.