To understand the impact human activities have on the planet, we need to monitor what surrounds us to evaluate if and how they change as a result of these activities
We are in an era where the impact of human activities on the planet is more and more noticeable. The fact that insurance companies are accounting for the impact of climate change in their policies is a testament that human activities are having direct repercussions on our lives. Although climate change is the most discussed human activity that impacts the planet and the organisms that live on it, there are numerous others, including forestry, mining, fishing, and air pollution.
We need to monitor biodiversity changes for an extended period of time, not only to grasp the impact of incremental changes on biodiversity (such as climate change) but also to capture the impact punctual dramatic events can have. For example, oil spills have been shown to change ecosystems for decades (Rohal et al. 2020)1.
To gain the full extent of the impact of such events, we need to have a monitoring program already in place to understand how biodiversity changed. For example, the permanent forest inventory plot on Barro Colorado Island (in the Panama Channel) established in the early 1980s, where all trees within 500 meters by 1-kilometer area are measured and identified every five years, was used to study how biodiversity is impacted by El Niño events.
It is with long-term studies that climatologists were able to assess how climate has been changing at an unprecedented speed. With biodiversity, we know that human activities have had an impact, but the scale and breadth of it is not as well defined as it is for climate. Aside from economically appealing systems such as forest trees and fisheries, long-lasting biodiversity monitoring projects are more the exception than the norm.
Learning how the boreal forest shrubs, mosses and insects change through time may seem unappealing and useless in the public’s eye, yet, these organisms are very important to maintain the biodiversity that people typically see (bears, elk, deer) and use (trees in a forest) and on which rests the cultural basis of northern societies. This is not limited to the First Nations. For example, camping, hunting and fishing are common activities in the boreal forest that have cultural significance across all areas of the world where boreal forests are found. Although human activity is known to have an impact on shrubs, mosses and insects, it is still unclear how and to which extent it affects these organisms. Large-scale, long-term studies are thus essential not only to understand how living things are changing but also to help us predict these changes and offer potential directions to manage these natural systems more efficiently.
The complexity of biodiversity
Unlike many scientific problems, biodiversity monitoring is unique because it requires gathering information on multiple hierarchical levels of the things that live. In collaboration with the scientific community, the Group on Earth Observations Biodiversity Observation Network (GEO BON) developed 21 Essential Biodiversity Variables (divided into six general classes) highlighting what is important to measure to quantify all aspects of biodiversity. This encompasses gathering data from genes to ecosystems. Gathering such diversity of data across all regions of the globe is a herculean task for which biodiversity scientists are very badly equipped to tackle mainly because they do not have the resources to achieve this task. Of all the Essential Biodiversity Variables, most of the work is currently focused on assessing species distribution, that is, to define a region on a map where a species is well adapted to live.
To study species distribution, we first need to distinguish different species. Even with scientists having been interested in defining and describing species for a few centuries, biodiversity experts are still struggling to identify all species on Earth. This task turns out to be a highly challenging one. As of today, there are still debates on how many species exist on Earth. Even if we identified roughly 2 million species so far, the number of species that remain to be discovered and identified is still a mystery, with specialists suggesting that the total number of species that live on Earth could range from as low as a few million to as high as a few hundred million (May 2010)2.
The good news is that from a practical perspective, the task of identifying all species on Earth is one we know how to do. DNA barcoding (Hebert et al. 2003)3 was shown to be efficient in identifying species using a DNA sample from an organism. The bad news is that in a recent assessment made by Paul Hebert in a talk given at the Montréal GEO BON conference in October 2023, the cost of identifying all species on Earth was estimated to be roughly 800 million dollars. Given the uncertainty of the number of species there could be on Earth, this value could likely be revised by a few (hundreds of) millions of dollars.
The challenges of biodiversity monitoring
Once we identify a species, we need to understand how it survives and reproduces if we want to manage it properly. This requires a lot of effort to be placed on monitoring this species for an extended period of time, hence the importance of developing long-term biodiversity monitoring programs. Biodiversity monitoring is a challenging task because to understand how a species survives and reproduces, scientists must be clever to find ways to study what makes a species live and thrive without their observations affecting individuals of the species.
That being said, because of advances in theoretical ecology, biodiversity experts know that what affects the ability of individuals of a species to reproduce and survive is directly related to how it interacts with other species (the living stuff) and with the environment (the non-living stuff). However, and this is the sticky problem, learning which other species and components of the environment are most important for a specific species requires groundwork, which is often very demanding in practice.
For example, the copper redhorse, a freshwater fish found only in southern Québec, is classified as endangered on the International Union for Conservation of Nature Red List of threatened species. The Red List compiles and maintains an updated inventory of the conservation and extinction status of species. Although the copper redhorse has had an endangered status since 2007, and consistent efforts to study and maintain the species have been ongoing for over two decades, we have seen little to no improvement in the species getting better. That is, we have not seen the size of the only known population increasing from its worryingly small size of 20 years ago. Scientific knowledge of the factors affecting the survival and reproduction of the copper redhorse in its natural habitat is still sparse, even after studying it for such a long time. One of the main reasons why it takes such a long time to learn about the copper redhorse is that it is a species that lives between 20 to 25 years and starts reproducing at 10 years old (Bannester-Marchand et al. submitted)4. This means that although we have been gathering yearly data on the species for over two decades, we actually have studied it for only about two generations. The example of the copper redhorse is one of many that highlights the difficulty of studying biodiversity.
Being creative about gathering biodiversity information
The classic way for scientists to gather data on species is to perform surveys, where records of individuals of one or multiple species are gathered in a systematic way. To study changes, we need to carry out these surveys regularly across extended periods of time. Although surveys are great because of the high-quality data that comes out of this work, they are expensive, especially when they are carried out in remote areas. Even if they are essential to learning about biodiversity, because the constraint of gathering reliable biodiversity data can be complex, recently, scientists have developed new creative ways to get information on species in nature.
In the last 10 to 15 years, there have been a lot of technological developments that allowed scientists to gather more complete data on the distribution of species and how it changes through time. Arguably one of the most impressive new data came from citizen science projects. Relying on accessible and easy to use web infrastructure like eBird and iNaturalist and the widespread use of smartphone, it is now easier than ever for anyone to gather quality data on biodiversity and make these data available. Citizen science projects have been a gold mine for scientists, especially for charismatic groups of species like birds, because these data bring a new source of information that is often quite complete on where and when species have been seen. And the amount of data available is impressive.
For example, the Global Biodiversity Information Facility, an international network dedicated to making worldwide biodiversity data available freely, currently offers the possibility to work with nearly 3 billion observations on biodiversity with data dating as far back as the middle of the 16th century. This wealth of biodiversity information offers great potential to study changes in biodiversity over time. Let’s only hope that the interest in biodiversity by the general public continues to increase.
Modelling where species live
Unlike all other fields, developing a model to define where a species will be found and how it may change through time is extremely complex. Even if we have a good understanding of what components of the environment (temperature, precipitation, elevation, urbanization, etc.) and which other species interact with the species, it is still a very challenging task. Actually, there are only a limited number of species for which all of this data and knowledge is readily available (namely trees). To understand and propose management decisions on species distribution, we need models that can convey information at a high resolution in space. In this respect, the main problem with modelling how species distribution changes through time is computational.
Although statisticians and computer scientists have made great strides in recent years, especially with the broad use of cluster computers and the refinement of artificial intelligence algorithms, the computational power required to build a useful model to define a map of the distribution of a species is very large. This is a major limitation for which little has recently been done specifically for biodiversity science. If we want to get a good understanding of how species distribution changes through time and, more broadly, of how biodiversity changes, it will be important to invest time and money in developing tools that are well-adapted to approach the complexity of biodiversity.
Why is this important?
Understanding and predicting when and where species will be found is far from being an academic endeavour. Aside from conserving charismatic species, there are many reasons why we may want to know more about how the distribution of species changes through time. Although it may seem futile to learn about the distribution of many species like creepy crawlers, many of these species have a surprising impact on nature. For example, earthworms are an invasive species in the northern parts of North America, and their presence strongly influences the lower vegetation, especially in forested areas.
Similarly, understanding how the distribution of some species changes through time may be highly important from a public health perspective. For example, with climate change, Canadians have seen the arrival of a few diseases transmitted by insects, such as Lyme diseases, transmitted by black-legged ticks or the West Nile virus transmitted by mosquitoes. These diseases were unheard of a few decades ago in Canada and have forced public health scientists to work with ecologists to study if, how and when insects that transmit different diseases may arrive in Canada. Work on modelling change in mosquito distributions is currently underway to prepare for the arrival of numerous mosquitoes transmitted diseases that until now have been typically found in warmer climates.
Only with enough good-quality biodiversity data and well-adapted modelling tools will it be possible to make accurate predictions based on which we can make management decisions that will have a true impact on biodiversity. In all other circumstances, our actions will be no more than guesses that are as likely to succeed as the chance of ‘getting a head’ when flipping a coin.
References
- https://doi.org/10.1016/j.ecolind.2020.106593
- https://www.science.org/doi/10.1126/science.1191058
- https://doi.org/10.1098/rspb.2002.2218
- Bannester-Marchand, N., N. Vachon, N. E. Mandrak and F.G. Blanchet. Submitted. Population viability analysis of the endangered Copper Redhorse (Moxostoma hubbsi).
