Seismic tomography

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Seismic_tomography 

Seismic tomography or seismotomography is a technique for imaging the subsurface of the Earth using seismic waves. The properties of seismic waves are modified by the material through which they travel. By comparing the differences in seismic waves recorded at different locations, it is possible to create a model of the subsurface structure. Most commonly, these seismic waves are generated by earthquakes or man-made sources such as explosions. Different types of waves, including P, S, Rayleigh, and Love waves can be used for tomographic images, though each comes with their own benefits and downsides and are used depending on the geologic setting, seismometer coverage, distance from nearby earthquakes, and required resolution. The model created by tomographic imaging is almost always a seismic velocity model, and features within this model may be interpreted as structural, thermal, or compositional variations. Geoscientists apply seismic tomography to a wide variety of settings in which the subsurface structure is of interest, ranging in scale from whole-Earth structure to the upper few meters below the surface.

Theory

Tomography is solved as an inverse problem. Seismic data are compared to an initial Earth model and the model is modified until the best possible fit between the model predictions and observed data is found. Seismic waves would travel in straight lines if Earth was of uniform composition, but structural, chemical, and thermal variations affect the properties of seismic waves, most importantly their velocity, leading to the reflection and refraction of these waves. The location and magnitude of variations in the subsurface can be calculated by the inversion process, although solutions to tomographic inversions are non-unique. Most commonly, only the travel time of the seismic waves is considered in the inversion. However, advances in modeling techniques and computing power have allowed different parts, or the entirety, of the measured seismic waveform to be fit during the inversion.

Seismic tomography is similar to medical x-ray computed tomography (CT scan) in that a computer processes receiver data to produce a 3D image, although CT scans use attenuation instead of travel-time difference. Seismic tomography has to deal with the analysis of curved ray paths which are reflected and refracted within the Earth, and potential uncertainty in the location of the earthquake hypocenter. CT scans use linear x-rays and a known source.

History

In the early 20th century, seismologists first used travel time variations in seismic waves from earthquakes to make discoveries such as the existence of the Moho and the depth to the outer core. While these findings shared some underlying principles with seismic tomography, modern tomography itself was not developed until the 1970s with the expansion of global seismic networks. Networks like the World-Wide Standardized Seismograph Network were initially motivated by underground nuclear tests, but quickly showed the benefits of their accessible, standardized datasets for geoscience. These developments occurred concurrently with advancements in modeling techniques and computing power that were required to solve large inverse problems and generate theoretical seismograms, which are required to test the accuracy of a model. As early as 1972, researchers successfully used some of the underlying principles of modern seismic tomography to search for fast and slow areas in the subsurface.

The first widely cited publication that largely resembles modern seismic tomography was published in 1976 and used local earthquakes to determine the 3D velocity structure beneath Southern California. The following year, P wave delay times were used to create 2D velocity maps of the whole Earth at several depth ranges, representing an early 3D model. The first model using iterative techniques, which improve upon an initial model in small steps and are required when there are a large number of unknowns, was done in 1984. The model was made possible by iterating upon the first radially anisotropic Earth model, created in 1981. A radially anisotropic Earth model describes changes in material properties, specifically seismic velocity, along a radial path through the Earth, and assumes this profile is valid for every path from the core to the surface. This 1984 study was also the first to apply the term "tomography" to seismology, as the term had originated in the medical field with X-ray tomography.

Seismic tomography has continued to improve in the past several decades since its initial conception. The development of adjoint inversions, which are able to combine several different types of seismic data into a single inversion, help negate some of the trade-offs associated with any individual data type. Historically, seismic waves have been modeled as 1D rays, a method referred to as "ray theory" that is relatively simple to model and can usually fit travel-time data well. However, recorded seismic waveforms contain much more information than just travel-time and are affected by a much wider path than is assumed by ray theory. Methods like the finite-frequency method attempt to account for this within the framework of ray theory. More recently, the development of "full waveform" or "waveform" tomography has abandoned ray theory entirely. This method models seismic wave propagation in its full complexity and can yield more accurate images of the subsurface. Originally these inversions were developed in exploration seismology in the 1980s and 1990s and were too computationally complex for global and regional scale studies, but development of numerical modeling methods to simulate seismic waves has allowed waveform tomography to become more common.

Process

Seismic tomography uses seismic records to create 2D and 3D models of the subsurface through an inverse problem that minimizes the difference between the created model and the observed seismic data. Various methods are used to resolve anomalies in the crust, lithosphere, mantle, and core based on the availability of data and types of seismic waves that pass through the region. Longer wavelengths penetrate deeper into the Earth, but seismic waves are not sensitive to features significantly smaller than their wavelength and therefore provide a lower resolution. Different methods also make different assumptions, which can have a large effect on the image created. For example, commonly used tomographic methods work by iteratively improving an initial input model, and thus can produce unrealistic results if the initial model is unreasonable.

P wave data are used in most local models and global models in areas with sufficient earthquake and seismograph density. S and surface wave data are used in global models when this coverage is not sufficient, such as in ocean basins and away from subduction zones. First-arrival times are the most widely used, but models utilizing reflected and refracted phases are used in more complex models, such as those imaging the core. Differential traveltimes between wave phases or types are also used.

Local tomography

Local tomographic models are often based on a temporary seismic array targeting specific areas, unless in a seismically active region with extensive permanent network coverage. These allow for the imaging of the crust and upper mantle.

• Diffraction and wave equation tomography use the full waveform, rather than just the first arrival times. The inversion of amplitude and phases of all arrivals provide more detailed density information than transmission traveltime alone. Despite the theoretical appeal, these methods are not widely employed because of the computing expense and difficult inversions.
• Reflection tomography originated with exploration geophysics. It uses an artificial source to resolve small-scale features at crustal depths. Wide-angle tomography is similar, but with a wide source to receiver offset. This allows for the detection of seismic waves refracted from sub-crustal depths and can determine continental architecture and details of plate margins. These two methods are often used together.
• Local earthquake tomography is used in seismically active regions with sufficient seismometer coverage. Given the proximity between source and receivers, a precise earthquake focus location must be known. This requires the simultaneous iteration of both structure and focus locations in model calculations.
• Teleseismic tomography uses waves from distant earthquakes that deflect upwards to a local seismic array. The models can reach depths similar to the array aperture, typically to depths for imaging the crust and lithosphere (a few hundred kilometers). The waves travel near 30° from vertical, creating a vertical distortion to compact features.

Regional or global tomography

Simplified and interpreted P and S wave velocity variations in the mantle across southern North America showing the subducted Farallon plate.

Regional to global scale tomographic models are generally based on long wavelengths. Various models have better agreement with each other than local models due to the large feature size they image, such as subducted slabs and superplumes. The trade off from whole mantle to whole Earth coverage is the coarse resolution (hundreds of kilometers) and difficulty imaging small features (e.g. narrow plumes). Although often used to image different parts of the subsurface, P and S wave derived models broadly agree where there is image overlap. These models use data from both permanent seismic stations and supplementary temporary arrays.

• First arrival traveltime P wave data are used to generate the highest resolution tomographic images of the mantle. These models are limited to regions with sufficient seismograph coverage and earthquake density, therefore cannot be used for areas such as inactive plate interiors and ocean basins without seismic networks. Other phases of P waves are used to image the deeper mantle and core.
• In areas with limited seismograph or earthquake coverage, multiple phases of S waves can be used for tomographic models. These are of lower resolution than P wave models, due to the distances involved and fewer bounce-phase data available. S waves can also be used in conjunction with P waves for differential arrival time models.
• Surface waves can be used for tomography of the crust and upper mantle where no body wave (P and S) data are available. Both Rayleigh and Love waves can be used. The low frequency waves lead to low resolution models, therefore these models have difficulty with crustal structure. Free oscillations, or normal mode seismology, are the long wavelength, low frequency movements of the surface of the Earth which can be thought of as a type of surface wave. The frequencies of these oscillations can be obtained through Fourier transformation of seismic data. The models based on this method are of broad scale, but have the advantage of relatively uniform data coverage as compared to data sourced directly from earthquakes.
• Attenuation tomography attempts to extract the anelastic signal from the elastic-dominated waveform of seismic waves. Generally, it is assumed that seismic waves behave elastically, meaning individual rock particles that are displaced by the seismic wave eventually return to their original position. However, a comparatively small amount of permanent deformation does occur, which adds up to significant energy loss over large distances. This anelastic behavior is called attenuation, and in certain conditions can become just as important as the elastic response. It has been shown that the contribution of anelasticity to seismic velocity is highly sensitive to temperature, so attenuation tomography can help determine if a velocity feature is caused by a thermal or chemical variation, which can be ambiguous when assuming a purely elastic response.
• Ambient noise tomography uses random seismic waves generated by oceanic and atmospheric disturbances to recover the velocities of surface waves. Assuming ambient seismic noise is equal in amplitude and frequency content from all directions, cross-correlating the ambient noise recorded at two seismometers for the same time period should produce only seismic energy that travels from one station to the other. This allows one station to be treated as a "virtual source" of surface waves sent to the other station, the "virtual receiver". These surface waves are sensitive to the seismic velocity of the Earth at different depths depending on their period. A major advantage of this method is that it does not require an earthquake or man-made source. A disadvantage of the method is that an individual cross-correlation can be quite noisy due to the complexity of the real ambient noise field. Thus, many individual correlations over a shorter time period, typically one day, need to be created and averaged to improve the signal-to-noise ratio. While this has often required very large amounts of seismic data recorded over multiple years, more recent studies have successfully used much shorter time periods to create tomographic images with ambient noise.
• Waveforms are usually modeled as rays due to ray theory being significantly less complex to model than the full seismic wave equations. However, seismic waves are affected by the material properties of a wide area surrounding the ray path, not just the material through which the ray passes directly. The finite frequency effect is the result the surrounding medium has on a seismic record. Finite frequency tomography accounts for this in determining both travel time and amplitude anomalies, increasing image resolution. This has the ability to resolve much larger variations (i.e. 10–30%) in material properties.

Applications

Seismic tomography can resolve anisotropy, anelasticity, density, and bulk sound velocity. Variations in these parameters may be a result of thermal or chemical differences, which are attributed to processes such as mantle plumes, subducting slabs, and mineral phase changes. Larger scale features that can be imaged with tomography include the high velocities beneath continental shields and low velocities under ocean spreading centers.

Hotspots

The African large low-shear-velocity province (superplume)

The mantle plume hypothesis proposes that areas of volcanism not readily explained by plate tectonics, called hotspots, are a result of thermal upwelling within the mantle. Some researchers have proposed an upper mantle source above the 660km discontinuity for these plumes, while others propose a much deeper source, possibly at the core-mantle boundary.

While the source of mantle plumes has been highly debated since they were first proposed in the 1970s, most modern studies argue in favor of mantle plumes originating at or near the core-mantle boundary. This is in large part due to tomographic images that reveal both the plumes themselves as well as large low-velocity zones in the deep mantle that likely contribute to the formation of mantle plumes. These large low-shear velocity provinces as well as smaller ultra low velocity zones have been consistently observed across many tomographic models of the deep Earth

Subduction Zones

Subducting plates are colder than the mantle into which they are moving. This creates a fast anomaly that is visible in tomographic images. Tomographic images have been made of most subduction zones around the world and have provided insight into the geometries of the crust and upper mantle in these areas. These images have revealed that subducting plates vary widely in how steeply they move into the mantle. Tomographic images have also seen features such as deeper portions of the subducting plate tearing off from the upper portion.

Other applications

Tomography can be used to image faults to better understand their seismic hazard. This can be through imaging the fault itself by seeing differences in seismic velocity across the fault boundary or by determining near-surface velocity structure, which can have a large impact on the magnitude on the amplitude of ground-shaking during an earthquake due to site amplification effects. Near-surface velocity structure from tomographic images can also be useful for other hazards, such as monitoring of landslides for changes in near-surface moisture content which has an effect on both seismic velocity and potential for future landslides.

Tomographic images of volcanoes have yielded new insights into properties of the underlying magmatic system. These images have most commonly been used to estimate the depth and volume of magma stored in the crust, but have also been used to constrain properties such as the geometry, temperature, or chemistry of the magma. It is important to note that both lab experiments and tomographic imaging studies have shown that recovering these properties from seismic velocity alone can be difficult due to the complexity of seismic wave propagation through focused zones of hot, potentially melted rocks.

While comparatively primitive to tomography on Earth, seismic tomography has been proposed on other bodies in the Solar System and successfully used on the Moon. Data collected from four seismometers placed by the Apollo missions have been used many times to create 1-D velocity profiles for the moon, and less commonly 3-D tomographic models. Tomography relies on having multiple seismometers, but tomography-adjacent methods for constraining Earth structure have been used on other planets. While on Earth these methods are often used in combination with seismic tomography models to better constrain the locations of subsurface features, they can still provide useful information about the interiors of other planetary bodies when only a single seismometer is available. For example, data gathered by the SEIS (Seismic Experiment for Interior Structure) instrument on InSight on Mars has been able to detect the Martian core.

Limitations

Global seismic networks have expanded steadily since the 1960s, but are still concentrated on continents and in seismically active regions. Oceans, particularly in the southern hemisphere, are under-covered. Temporary seismic networks have helped improve tomographic models in regions of particular interest, but typically only collect data for months to a few years. The uneven distribution of earthquakes biases tomographic models towards seismically active regions. Methods that do not rely on earthquakes such as active source surveys or ambient noise tomography have helped image areas with little to no seismicity, though these both have their own limitations as compared to earthquake-based tomography.

The type of seismic wave used in a model limits the resolution it can achieve. Longer wavelengths are able to penetrate deeper into the Earth, but can only be used to resolve large features. Finer resolution can be achieved with surface waves, with the trade off that they cannot be used in models deeper than the crust and upper mantle. The disparity between wavelength and feature scale causes anomalies to appear of reduced magnitude and size in images. P and S wave models respond differently to the types of anomalies. Models based solely on the wave that arrives first naturally prefer faster pathways, causing models based on these data to have lower resolution of slow (often hot) features. This can prove to be a significant issue in areas such as volcanoes where rocks are much hotter than their surroundings and oftentimes partially melted. Shallow models must also consider the significant lateral velocity variations in continental crust.

Because seismometers have only been deployed in large numbers since the late-20th century, tomography is only capable of viewing changes in velocity structure over decades. For example, tectonic plates only move at millimeters per year, so the total amount of change in geologic structure due to plate tectonics since the development of seismic tomography is several orders of magnitude lower than the finest resolution possible with modern seismic networks. However, seismic tomography has still been used to view near-surface velocity structure changes at time scales of years to months.

Tomographic solutions are non-unique. Although statistical methods can be used to analyze the validity of a model, unresolvable uncertainty remains. This contributes to difficulty comparing the validity of different model results.

Computing power limits the amount of seismic data, number of unknowns, mesh size, and iterations in tomographic models. This is of particular importance in ocean basins, which due to limited network coverage and earthquake density require more complex processing of distant data. Shallow oceanic models also require smaller model mesh size due to the thinner crust.

Tomographic images are typically presented with a color ramp representing the strength of the anomalies. This has the consequence of making equal changes appear of differing magnitude based on visual perceptions of color, such as the change from orange to red being more subtle than blue to yellow. The degree of color saturation can also visually skew interpretations. These factors should be considered when analyzing images.

Environmental resource management

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Environmental_resource_management

The shrinking Aral Sea, an example of poor water resource management diverted for irrigation

Environmental resource management or environmental management is the management of the interaction and impact of human societies on the environment. It is not, as the phrase might suggest, the management of the environment itself. Environmental resources management aims to ensure that ecosystem services are protected and maintained for future human generations, and also maintain ecosystem integrity through considering ethical, economic, and scientific (ecological) variables. Environmental resource management tries to identify factors between meeting needs and protecting resources. It is thus linked to environmental protection, resource management, sustainability, integrated landscape management, natural resource management, fisheries management, forest management, wildlife management, environmental management systems, and others.

Significance

Environmental resource management is an issue of increasing concern, as reflected in its prevalence in several texts influencing global sociopolitical frameworks such as the Brundtland Commission's Our Common Future, which highlighted the integrated nature of the environment and international development, and the Worldwatch Institute's annual State of the World reports.

The environment determines the nature of people, animals, plants, and places around the Earth, affecting behaviour, religion, culture and economic practices.

Scope

Improved agricultural practices such as these terraces in northwest Iowa can serve to preserve soil and improve water quality.

Environmental resource management can be viewed from a variety of perspectives. It involves the management of all components of the biophysical environment, both living (biotic) and non-living (abiotic), and the relationships among all living species and their habitats. The environment also involves the relationships of the human environment, such as the social, cultural, and economic environment, with the biophysical environment. The essential aspects of environmental resource management are ethical, economical, social, and technological. These underlie principles and help make decisions.

The concept of environmental determinism, probabilism, and possibilism are significant in the concept of environmental resource management.

Environmental resource management covers many areas in science, including geography, biology, social sciences, political sciences, public policy, ecology, physics, chemistry, sociology, psychology, and physiology. Environmental resource management as a practice and discourse (across these areas) is also the object of study in the social sciences.

Aspects

Ethical

Environmental resource management strategies are intrinsically driven by conceptions of human-nature relationships. Ethical aspects involve the cultural and social issues relating to the environment, and dealing with changes to it. "All human activities take place in the context of certain types of relationships between society and the bio-physical world (the rest of nature)," and so, there is a great significance in understanding the ethical values of different groups around the world. Broadly speaking, two schools of thought exist in environmental ethics: Anthropocentrism and Ecocentrism, each influencing a broad spectrum of environmental resource management styles along a continuum. These styles perceive "...different evidence, imperatives, and problems, and prescribe different solutions, strategies, technologies, roles for economic sectors, culture, governments, and ethics, etc."

Anthropocentrism

Main article: Anthropocentrism

Anthropocentrism, "an inclination to evaluate reality exclusively in terms of human values," is an ethic reflected in the major interpretations of Western religions and the dominant economic paradigms of the industrialised world. Anthropocentrism looks at nature as existing solely for the benefit of humans, and as a commodity to use for the good of humanity and to improve human quality of life. Anthropocentric environmental resource management is therefore not the conservation of the environment solely for the environment's sake, but rather the conservation of the environment, and ecosystem structure, for humans' sake.

Ecocentrism

Main article: Ecocentrism

Ecocentrists believe in the intrinsic value of nature while maintaining that human beings must use and even exploit nature to survive and live. It is this fine ethical line that ecocentrists navigate between fair use and abuse. At an extreme of the ethical scale, ecocentrism includes philosophies such as ecofeminism and deep ecology, which evolved as a reaction to dominant anthropocentric paradigms. "In its current form, it is an attempt to synthesize many old and some new philosophical attitudes about the relationship between nature and human activity, with particular emphasis on ethical, social, and spiritual aspects that have been downplayed in the dominant economic worldview."

Economics

Main article: Economics

A water harvesting system collects rainwater from the Rock of Gibraltar into pipes that lead to tanks excavated inside the rock.

The economy functions within and is dependent upon goods and services provided by natural ecosystems. The role of the environment is recognized in both classical economics and neoclassical economics theories, yet the environment was a lower priority in economic policies from 1950 to 1980 due to emphasis from policy makers on economic growth. With the prevalence of environmental problems, many economists embraced the notion that, "If environmental sustainability must coexist for economic sustainability, then the overall system must [permit] identification of an equilibrium between the environment and the economy." As such, economic policy makers began to incorporate the functions of the natural environment – or natural capital – particularly as a sink for wastes and for the provision of raw materials and amenities.

Debate continues among economists as to how to account for natural capital, specifically whether resources can be replaced through knowledge and technology, or whether the environment is a closed system that cannot be replenished and is finite. Economic models influence environmental resource management, in that management policies reflect beliefs about natural capital scarcity. For someone who believes natural capital is infinite and easily substituted, environmental management is irrelevant to the economy. For example, economic paradigms based on neoclassical models of closed economic systems are primarily concerned with resource scarcity and thus prescribe legalizing the environment as an economic externality for an environmental resource management strategy. This approach has often been termed 'Command-and-control'. Colby has identified trends in the development of economic paradigms, among them, a shift towards more ecological economics since the 1990s.

Ecology

A diagram showing the juvenile fish bypass system, which allows young salmon and steelhead to safely pass the Rocky Reach Hydro Project in Washington

Fencing separates big game from vehicles along the Quebec Autoroute 73 in Canada.

There are many definitions of the field of science commonly called ecology. A typical one is "the branch of biology dealing with the relations and interactions between organisms and their environment, including other organisms." "The pairing of significant uncertainty about the behaviour and response of ecological systems with urgent calls for near-term action constitutes a difficult reality, and a common lament" for many environmental resource managers. Scientific analysis of the environment deals with several dimensions of ecological uncertainty. These include: structural uncertainty resulting from the misidentification, or lack of information pertaining to the relationships between ecological variables; parameter uncertainty referring to "uncertainty associated with parameter values that are not known precisely but can be assessed and reported in terms of the likelihood…of experiencing a defined range of outcomes"; and stochastic uncertainty stemming from chance or unrelated factors. Adaptive management is considered a useful framework for dealing with situations of high levels of uncertainty though it is not without its detractors.

A common scientific concept and impetus behind environmental resource management is carrying capacity. Simply put, carrying capacity refers to the maximum number of organisms a particular resource can sustain. The concept of carrying capacity, whilst understood by many cultures over history, has its roots in Malthusian theory. An example is visible in the EU Water Framework Directive. However, "it is argued that Western scientific knowledge ... is often insufficient to deal with the full complexity of the interplay of variables in environmental resource management. These concerns have been recently addressed by a shift in environmental resource management approaches to incorporate different knowledge systems including traditional knowledge, reflected in approaches such as adaptive co-managemen community-based natural resource management and transitions management^[34] among others.

Sustainability

Main article: Sustainability and environmental management

Sustainability in environmental resource management involves managing economic, social, and ecological systems both within and outside an organizational entity so it can sustain itself and the system it exists in. In context, sustainability implies that rather than competing for endless growth on a finite planet, development improves quality of life without necessarily consuming more resources. Sustainably managing environmental resources requires organizational change that instills sustainability values that portrays these values outwardly from all levels and reinforces them to surrounding stakeholders. The result should be a symbiotic relationship between the sustaining organization, community, and environment.

Many drivers compel environmental resource management to take sustainability issues into account. Today's economic paradigms do not protect the natural environment, yet they deepen human dependency on biodiversity and ecosystem services. Ecologically, massive environmental degradation and climate change threaten the stability of ecological systems that humanity depends on. Socially, an increasing gap between rich and poor and the global North–South divide denies many access to basic human needs, rights, and education, leading to further environmental destruction. The planet's unstable condition is caused by many anthropogenic sources. As an exceptionally powerful contributing factor to social and environmental change, the modern organisation has the potential to apply environmental resource management with sustainability principles to achieve highly effective outcomes. To achieve sustainable development with environmental resource management an organisation should work within sustainability principles, including social and environmental accountability, long-term planning; a strong, shared vision; a holistic focus; devolved and consensus decision making; broad stakeholder engagement and justice; transparency measures; trust; and flexibility.

Current paradigm shifts

To adjust to today's environment of quick social and ecological changes, some organizations have begun to experiment with new tools and concepts. Those that are more traditional and stick to hierarchical decision making have difficulty dealing with the demand for lateral decision making that supports effective participation. Whether it be a matter of ethics or just strategic advantage organizations are internalizing sustainability principles. Some of the world's largest and most profitable corporations are shifting to sustainable environmental resource management: Ford, Toyota, BMW, Honda, Shell, Du Port, Sta toil, Swiss Re, Hewlett-Packard, and Unilever, among others. An extensive study by the Boston Consulting Group reaching 1,560 business leaders from diverse regions, job positions, expertise in sustainability, industries, and sizes of organizations, revealed the many benefits of sustainable practice as well as its viability.

Although the sustainability of environmental resource management has improved, corporate sustainability, for one, has yet to reach the majority of global companies operating in the markets. The three major barriers to preventing organizations from shifting towards sustainable practice with environmental resource management are not understanding what sustainability is; having difficulty modeling an economically viable case for the switch; and having a flawed execution plan, or a lack thereof. Therefore, the most important part of shifting an organization to adopt sustainability in environmental resource management would be to create a shared vision and understanding of what sustainability is for that particular organization and to clarify the business case.

Stakeholders

Public sector

A conservation project in North Carolina involving the search for bog turtles was conducted by United States Fish and Wildlife Service and the North Carolina Wildlife Resources Commission and its volunteers.

The public sector comprises the general government sector plus all public corporations including the central bank. In environmental resource management the public sector is responsible for administering natural resource management and implementing environmental protection legislation. The traditional role of the public sector in environmental resource management is to provide professional judgement through skilled technicians on behalf of the public. With the increase of intractable environmental problems, the public sector has been led to examine alternative paradigms for managing environmental resources. This has resulted in the public sector working collaboratively with other sectors (including other governments, private and civil) to encourage sustainable natural resource management behaviours.

Private sector

The private sector comprises private corporations and non-profit institutions serving households. The private sector's traditional role in environmental resource management is that of the recovery of natural resources. Such private sector recovery groups include mining (minerals and petroleum), forestry and fishery organisations. Environmental resource management undertaken by the private sectors varies dependent upon the resource type, that being renewable or non-renewable and private and common resources (also see Tragedy of the Commons). Environmental managers from the private sector also need skills to manage collaboration within a dynamic social and political environment.

Civil society

Civil society comprises associations in which societies voluntarily organise themselves and which represent a wide range of interests and ties. These can include community-based organisations, indigenous peoples' organisations and non-government organisations (NGOs). Functioning through strong public pressure, civil society can exercise their legal rights against the implementation of resource management plans, particularly land management plans. The aim of civil society in environmental resource management is to be included in the decision-making process by means of public participation. Public participation can be an effective strategy to invoke a sense of social responsibility of natural resources.

Tools

As with all management functions, effective management tools, standards, and systems are required. An environmental management standard or system or protocol attempts to reduce environmental impact as measured by some objective criteria. The ISO 14001 standard is the most widely used standard for environmental risk management and is closely aligned to the European Eco-Management and Audit Scheme (EMAS). As a common auditing standard, the ISO 19011 standard explains how to combine this with quality management.

Other environmental management systems (EMS) tend to be based on the ISO 14001 standard and many extend it in various ways:

• The Green Dragon Environmental Management Standard is a five-level EMS designed for smaller organisations for whom ISO 14001 may be too onerous and for larger organisations who wish to implement ISO 14001 in a more manageable step-by-step approach,
• BS 8555 is a phased standard that can help smaller companies move to ISO 14001 in six manageable steps,
• The Natural Step focuses on basic sustainability criteria and helps focus engineering on reducing use of materials or energy use that is unsustainable in the long term,
• Natural Capitalism advises using accounting reform and a general biomimicry and industrial ecology approach to do the same thing,
• US Environmental Protection Agency has many further terms and standards that it defines as appropriate to large-scale EMS,
• The UN and World Bank has encouraged adopting a "natural capital" measurement and management framework.

Other strategies exist that rely on making simple distinctions rather than building top-down management "systems" using performance audits and full cost accounting. For instance, Ecological Intelligent Design divides products into consumables, service products or durables and unsaleables – toxic products that no one should buy, or in many cases, do not realize they are buying. By eliminating the unsaleables from the comprehensive outcome of any purchase, better environmental resource management is achieved without systems.

Another example that diverges from top-down management is the implementation of community based co-management systems of governance. An example of this is community based subsistence fishing areas, such as is implemented in Ha'ena, Hawaii. Community based systems of governance allow for the communities who most directly interact with the resource and who are most deeply impacted by the overexploitation of said resource to make the decisions regarding its management, thus empowering local communities and more effectively managing resources.

Recent successful cases have put forward the notion of integrated management. It shares a wider approach and stresses out the importance of interdisciplinary assessment. It is an interesting notion that might not be adaptable to all cases.

Case Study: Kissidougou, Guinea (Fairhead, Leach)

Kissidougou, Guinea’s dry season brings about fires in the open grass fires which defoliate the few trees in the savanna. There are villages within this savanna surrounded by “islands” of forests, allowing for forts, hiding, rituals, protection from wind and fire, and shade for crops. According to scholars and researchers in the region during the late-19th and 20th centuries, there was a steady decline in tree cover. This led to colonial Guinea’s implementation of policies, including the switch of upland to swamp farming; bush-fire control; protection of certain species and land; and tree planting in villages. These policies were carried out in the form of permits, fines, and military repression.

But, Kissidougou villagers claim their ancestors’ established these islands. Many maps and letters evidence France’s occupation of Guinea, as well as Kissidougou’s past landscape. During the 1780s to 1860s “the whole country [was] prairie.” James Fairhead and Melissa Leach, both environmental anthropologists at the University of Sussex, claim the state’s environmental analyses “casts into question the relationships between society, demography, and environment.” With this, they reformed the state’s narratives: Local land use can be both vegetation enriching and degrading; combined effect on resource management is greater than the sum of their parts; there is evidence of increased population correlating to an increase in forest cover. Fairhead and Leach support the enabling of policy and socioeconomic conditions in which local resource management conglomerates can act effectively. In Kissidougou, there is evidence that local powers and community efforts shaped the island forests that shape the savanna’s landscape.

Ecosystem-based management

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Ecosystem-based_management 

Ecosystem-based management is an environmental management approach that recognizes the full array of interactions within an ecosystem, including humans, rather than considering single issues, species, or ecosystem services in isolation. It can be applied to studies in the terrestrial and aquatic environments with challenges being attributed to both. In the marine realm, they are highly challenging to quantify due to highly migratory species as well as rapidly changing environmental and anthropogenic factors that can alter the habitat rather quickly. To be able to manage fisheries efficiently and effectively it has become increasingly more pertinent to understand not only the biological aspects of the species being studied, but also the environmental variables they are experiencing. Population abundance and structure, life history traits, competition with other species, where the stock is in the local food web, tidal fluctuations, salinity patterns and anthropogenic influences are among the variables that must be taken into account to fully understand the implementation of a "ecosystem-based management" approach. Interest in ecosystem-based management in the marine realm has developed more recently, in response to increasing recognition of the declining state of fisheries and ocean ecosystems. However, due to a lack of a clear definition and the diversity involved with the environment, the implementation has been lagging. In freshwater lake ecosystems, it has been shown that ecosystem-based habitat management is more effective for enhancing fish populations than management alternatives.

Terrestrial ecosystem-based management (often referred to as ecosystem management) came into its own during the conflicts over endangered species protection (particularly the northern spotted owl), land conservation, and water, grazing and timber rights in the western United States in the 1980s and 1990s.

History

The systemic origins of ecosystem-based management are rooted in the ecosystem management policy applied to the Great Lakes of North America in the late 1970s. The legislation created, the "Great Lakes Basin and the Great Lakes Water Quality Agreement of 1978", was based on the claim that "no park is an island", with the purpose to show how strict protection of the area is not the best method for preservation. This type of management system was however an idea that began long before and evolved through the testing and challenging of common ecosystem management practices.

Before its complete synthesis, the management system's historical development can be traced back to the 1930s. During this time, the scientific communities who studied ecology realized that current approaches to the management of national parks did not provide effective protection of the species within. In 1932, The Ecological Society of America's Committee for the Study of Plant and Animal Communities recognized that US national parks needed to protect all the ecosystems contained within the park in order to create an inclusive and fully functioning sanctuary, and be prepared to handle natural fluctuations in its ecology. Also the committee explained the importance for interagency cooperation and improved public education, as well as challenged the idea that proper park management would "improve" nature. These ideas became the foundation of modern ecosystem-based management.

As the understanding of how to manage ecosystems shifted, new tenets of the management system were produced. Biologists George Wright and Ben Thompson accounted for the size and boundary limitations of parks and contributed to the re-structuring of how park lines were drawn. They explained how large mammals for example could not be supported within the restricted zones of a national park and in order to protect these animals and their ecosystems a new approach would be needed. Other scientists followed suit, but none were successful in establishing a well-defined ecosystem-based management approach.

In 1979, the importance of ecosystem-based management resurfaced in ecology from two biologists: John and Frank Craighead. The Craigheads found that grizzly bears of Yellowstone National Park could not sustain a population if only allowed to live within park boundaries. This reinforced the idea that a broader definition of what defines an ecosystem needed to be created, suggesting that it be based on the biotic requirements of the largest mammal present.

The idea of ecosystem-based management began to catch on and projects throughout American National Parks reflected the idea of protecting an ecosystem in its entirety and not based on legal or ecological restrictions as previously used. Jim Agee and Darryll Johnson published a book-length report on managing ecosystems in 1988 explaining the theoretical framework management. While they did not fully embrace ecosystem-based management by still calling for "ecologically defined boundaries", they stated the importance of "clearly stated management goals, interagency cooperation, monitoring of management results, and leadership at the national policy levels". Most importantly they demanded the recognition of human influence. It was argued that scientists must keep in mind the "complex social context of their work" and always be moving towards "socially desirable conditions". This need to understand the social aspects of scientific management is the fundamental step from ecological management to ecosystem-based management.

Although it continues to become recognized, a debate over ecosystem-based management continues. Grumbine (1994) believes, while the approach has evolved, it has not been fully incorporated into management practices because the most effective forms of it have yet to be seen. He articulates that the current ecological climate calls for the most holistic approach of ecological management. This is in part due to the rapid decline in biodiversity and because of the constant state of flux in societal and political views of nature. Conflicts over public interest and understanding of the natural world have created social and political climates that require interagency cooperation, which stands as a backbone for ecosystem-based management.

Implementation

Because ecosystem-based management is applied to large, diverse areas encompassing an array of interactions between species, ecosystem components, and humans, it is often perceived as a complex process that is difficult to implement. Slocombe (1998b) also noted that in addition, uncertainty is common and predictions are difficult. However, in light of significant ecosystem degradation, there is a need for a holistic approach that combines environmental knowledge and co-ordination with governing agencies to initiate, sustain and enforce habitat and species protection, and include public education and involvement. As a result, ecosystem-based management will likely be increasingly used in the future as a form of environmental management. Some suggestions for implementing ecosystem-based management and what the process may involve are as follows:

Goals and objectives

Defining clear and concise goals for ecosystem-based management is one of the most important steps in effective ecosystem-based management implementation. Goals must move beyond science-based or science-defined objectives to include social, cultural, economic and environmental importance. Of equal importance is to make sure that the community and stake-holders are involved throughout the entire process. Slocombe (1998a) also stated that a single, end-all goal cannot be the solution, but instead a combination of goals and their relationships with each other should be the focus.

As discussed by Slocombe (1998a), goals should be broadly applicable, measurable and readily observable, and ideally be collectively supported in order to be achievable. The idea is to provide direction for both thinking and action and should try to minimize managing ecosystems in a static state. Goals should also be flexible enough to incorporate a measure of uncertainty and be able to evolve as conditions and knowledge change. This may involve focusing on specific threatening processes, such as habitat loss or introduced invasive species, occurring within an ecosystem. Overall the goals should be integrative, to include the structure, organization and processes of the management of an area. Correct ecosystem-based management should be based in goals that are both "substantive", to explain the aims and importance of protecting an area, and "procedural", to explain how substantive goals will be met.

As described by Tallis et al. (2010), some steps of ecosystem-based management may include:

Scoping

This step involves the acquisition of data and knowledge from various sources in order to provide a thorough understanding of critical ecosystem components. Sources may include literature, informal sources such as aboriginal residents, resource users, and/or environmental experts. Data may also be gained through statistical analyses, simulation models, or conceptual models.

Defining indicators

Ecological indicators are useful for tracking or monitoring an ecosystem's status and can provide feedback on management progress as stressed by Slocombe (1998a). Examples may include the population size of a species or the levels of toxin present in a body of water. Social indicators may also be used such as the number or types of jobs within the environmental sector or the livelihood of specific social groups such as indigenous peoples.

Setting thresholds

Tallis et al. (2010) suggest setting thresholds for each indicator and setting targets that would represent a desired level of health for the ecosystem. Examples may include species composition within an ecosystem or the state of habitat conditions based on local observations or stakeholder interviews. Thresholds can be used to help guide management, particularly for a species by looking at the conservation status criteria established by either state or federal agencies and using models such as the minimum viable population size.

Risk analysis

A range of threats and disturbances, both natural and human, often can affect indicators. Risk is defined as the sensitivity of an indicator to an ecological disturbance. Several models can be used to assess risk such as population viability analysis.

Monitoring

Evaluating the effectiveness of the implemented management strategies is very important in determining how management actions are affecting the ecosystem indicators. Evaluation: This final step involves monitoring and assessing data to see how well the management strategies chosen are performing relative to the initial objectives stated. The use of simulation models or multi-stakeholder groups can help to assess management.

It is important to note that many of these steps for implementing ecosystem-based management are limited by the governance in place for a region, the data available for assessing ecosystem status and reflecting on the changes occurring, and the time frame in which to operate.

Challenges

Because ecosystems differ greatly and express varying degrees of vulnerability, it is difficult to apply a functional framework that can be universally applied. These outlined steps or components of ecosystem-based management can, for the most part, be applied to multiple situations and are only suggestions for improving or guiding the challenges involved with managing complex issues. Because of the greater amount of influences, impacts, and interactions to account for, problems, obstacles and criticism often arise within ecosystem-based management. There is also a need for more data, spatially and temporally to help management make sound decisions for the sustainability of the stock being studied.

The first commonly defined challenge is the need for meaningful and appropriate management units. Slocombe (1998b) noted that these units must be broad and contain value for people in and outside of the protected area. For example, Aberley (1993) suggests the use of "bioregions" as management units, which can allow peoples involvement with that region to come through. To define management units as inclusive regions rather that exclusive ecological zones would prevent further limitations created by narrow or restricting political and economic policy created from the units. Slocombe (1998b) suggests that better management units should be flexible and build from existing units and that the biggest challenge is creating truly effect units for managers to compare against.

Another issue is in the creation of administrative bodies. They should operate as the essence of ecosystem-based management, working together towards mutually agreed upon goals. Gaps in administration or research, competing objectives or priorities between management agencies and governments due to overlapping jurisdictions, or obscure goals such as sustainability, ecosystem integrity, or biodiversity can often result in fragmented or weak management. In addition, Tallis (2010) stated that limited knowledge of ecosystem components and function and time constraints that can often limit objectives to only those that can be addressed in the short-term.

The most challenging issue facing ecosystem-based management is that there exists little knowledge about the system and its effectiveness. Slocombe (1998b) stated that with limited resources available on how to implement the system it is hard to find support for its use.

Slocombe (1998a) said that criticism of ecosystem-based management include its reliance on analogy and comparisons, too broadly applied frameworks, its overlap with or duplication of other methods such as ecosystem management, environmental management, or integrated ecosystem assessment, its vagueness in concepts and application, and its tendency to ignore historical, evolutionary or individual factors that may heavily influence ecosystem functioning.

Tallis (2010) stated that ecosystem-based management is seen as a critical planning and management framework for conserving or restoring ecosystems though it is still not widely implemented. An ecosystem approach addresses many relationships across spatial, biological, and organizational scales and is a goal-driven approach to restoring and sustaining ecosystems and functions. In addition, ecosystem-based management involves community influence as well as planning and management from local, regional and national government bodies and management agencies. All must be in collaboration in order to develop a desired future of ecosystem conditions, particularly where ecosystems have undergone radical degradation and change. Slocombe (1998b) said that to move forward, ecosystem-based management should be approached through adaptive management, allowing flexibility and inclusiveness to deal with constant environmental, societal, and political change.

Marine systems

Ecosystem-based management of marine environments has begun to move away from the traditional strategies which focus on conservation of single species or single sectors in favor of an integrated approach which considers all key activities, particularly anthropogenic, that affect marine environments. Management must take into account the life history of the fish being studied, its association with the surrounding environment, its place in the food web, where it prefers to reside in the water column, and how it is affected by human pressures. The objective is to ensure sustainable ecosystems, thus protecting the resources and services they provide for future generations.

In recent years there has been increasing recognition of anthropogenic disruption to marine ecosystems resulting from climate change, overfishing, nutrient and chemical pollution from land runoff, coastal development, bycatch, and habitat destruction. The effect of human activity on marine ecosystems has become an important issue because many of the benefits provided to humans by marine ecosystems are declining. These services include the provision of food, fuel, mineral resources, pharmaceuticals, as well as opportunities for recreation, trade, research and education.

Guerry (2005) has identified an urgent need to improve the management of these declining ecosystems, particularly in coastal areas, to ensure sustainability. Human communities depend on marine ecosystems for important resources, but without holistic management, these ecosystems are likely to collapse. Olsson et al. (2008) suggest that the degradation of marine ecosystems is largely the result of poor governance and that new approaches to management are required. The Pew Oceans Commission and the United States Commission on Ocean Policy have indicated the importance of moving from current piecemeal management to a more integrated ecosystem-based approach.

Stock assessment

Dead salmon in spawning season

Stock assessment is a critically important aspect of fisheries management, but it is a highly complex, logistically difficult, and expensive process and can thus be a contentious issue, particularly when competing parties disagree on the findings of an assessment. Accurate stock assessments require knowledge of reproductive and morphological patterns, age-at-stage progressions, and movement ecology.

Bottom up or top down

Post-dip pose

All members of an ecosystem are affected by other organisms within that ecosystem, and proper management of wildlife requires knowledge of an organism's trophic level and its effects on other organisms within its food web. Top-down and bottom-up controls represent one method by which the numbers of wild populations of plants and animals are limited. Top-down controls have been seen in the explosion of sea urchins and subsequent decline in kelp beds due to the near-extirpation of sea otters.As otters were hunted nearly to extinction, sea urchins - preyed on by sea otters and which themselves feed on the kelp - boomed, resulting in the near-disappearance of kelp beds. Bottom-up controls are best illustrated when autotrophic primary producers such as plants and phytoplankton, which represent the lowest trophic level of an ecosystem, are limited, impacting all organisms in higher trophic levels, but bottom-up changes can also be seen in higher trophic levels. For example, the decline of North Sea puffins has been attributed to overexploitation of sand eels, an important prey item.

Bycatch

Red snapper is a species of enormous economic importance in the Gulf of Mexico. Management of this species is complicated by the large impact of bycatch associated with the shrimping industry. Rates of red snapper mortality are not explained by fishery landings, but are instead associated with large numbers of juvenile red snapper caught as bycatch in the fine mesh used by trawlers.

Key elements

Connections

At its core, ecosystem-based management is about acknowledging interdependency connections, including the linkages between marine ecosystems and human societies, economies and institutional systems, as well as those among various species within an ecosystem and among ocean places that are linked by the movement of species, materials, and ocean currents. Of particular importance is how these factors all react and involve each other. In the Caribbean, the spiny lobster is managed based on a classic population model that for most fishery species works quite well. However, this species will grow and then halt its growth when it need to molt its shell and thus instead of a continuous growth cycle, it will pause its growth and invest its energy in a new shell. To further complicate matters, it slows this process down as it gets older to invest more energy into reproduction thus further deviating itself from the von Bertalanffy model of growth that was applied to it. The more information we can gather about an ecosystem and all of the interconnected factors which affect it, the more capable we will be of better managing that system.

Cumulative impacts

Ecosystem-based management focuses on how individual actions affect the ecosystem services that flow from coupled socio-ecological systems in an integrated fashion, rather than considering these impacts in a piecemeal manner. Loss of biodiversity in marine ecosystems is an example of how cumulative effects from different sectors can impact on an ecosystem in a compounding way. Overfishing, coastal development, filling and dredging, mining and other human activities all contribute to the loss of biodiversity and therefore degradation of the ecosystem. Work is needed prior to the carrying out of the research to understand the total effects that each species can have on each other and also on the environment. It must be carried out every year as well as species are changing their life history traits and their relationship with the environment as humans are continually modifying the environment.

Interactions between sectors

The only way to deal with the cumulative effects of human influences on marine ecosystems is for various contributing sectors to set common goals for the protection or management of ecosystems. While some policies may only affect a single sector, others may affect multiple sectors. A policy for the protection of endangered marine species, for example, could affect recreational and commercial fisheries, mining, shipping and tourism sectors to name a few. More effective ecosystem management would result from the collective adoption of policies by all sectors, rather than each sector creating their own isolated policies. For example, in the Gulf of Mexico there are oil rigs, recreational fisheries, commercial fisheries and multiple tourist attractions. One of the main fisheries is that of the Red Snapper which inhabits much of the Gulf and employs thousands of people in the commercial and recreational fishery. During the Deepwater oil spill it became abundantly obvious that it negatively affected the population numbers as well as the integrity of the catch that was being made. The species not only suffered higher mortality rates but the market was less trusting of the product. An environmental disaster interacted with the commercial, recreational, and economic sector for a specific species.

Changing public perceptions

Not all members of the public will be properly informed, or be fully aware, of current threats to marine ecosystems and it is therefore important to change public perceptions by informing people about these issues. It is important to consider the interest of the public when making decisions about ocean management and not just those who have a material interest because community support is needed by management agencies in order to make decisions. The Great Barrier Reef Marine Park Authority (GBRMPA) faced the issue of poor public awareness in their proposed management strategy which included no-take fishing zones. Olssen (2008) addressed this problem by starting a 'reef under pressure' information campaign to prove to the public that the Great Barrier Reef is under threat from human disturbances, and in doing so were successful in gaining public support.

Bridging science and policy

To ensure that all key players are on the same page, it is important to have communication between managers, resource users, scientists, government bodies and other stakeholders. Leslie and McLeod (2007) stated that proper engagement between these groups will enable the development of management initiatives that are realistic and enforceable as well as effective for ecosystem management. If certain small-scale players are not involved or informed, it is highly unlikely and equally challenging to get them to cooperate as well as to follow the rules that need to be put in place. It is of the utmost importance to have every stakeholder involved with every step of the process to increase the cohesion of the process.

Embracing change

Coupled social-ecological systems are constantly changing in ways that cannot be fully predicted or controlled. Understanding the resilience of ecosystems, i.e. the extent to which they can maintain structure, function, and identity in the face of disturbance, can enable better prediction of how ecosystems will respond to both natural and anthropogenic perturbations, and to changes in environmental management. With how much modification humans are doing to environments, it is important to understand these changes on a yearly basis as well. Some species are changing their life histories, Flounder, due to the increased pressures that humans are placing on the environment. Thus, when a manager or government does an assessment on the ecosystem for a given year, the relationship that a species has to others can change very quickly and thus negate the model that you use for an ecosystem very quickly if not redefined.

Multiple objectives

Ecosystem-based management focuses on the diverse benefits provided by marine systems, rather than on single ecosystem services. Such benefits or services include vibrant commercial and recreational fisheries, biodiversity conservation, renewable energy from wind or waves and coastal protection. The goal is to provide a sustainable fisheries while incorporating the impacts of other aspects on that resource. When managed correctly, an ecosystem-based model can greatly improve not only the resource being managed, but those associated with it.

Learning and adaptation

Because of the lack of control and predictability of coupled social-ecological systems, an adaptive management approach is recommended. There can be multiple different factors that must be overcome (fisheries, pollution, borders, multiple agencies, etc.) to create a positive outcome. Managers must be able to react and adapt as to limit the variance associated with the outcome.

Other examples

Great Bear Rainforest - Canada

The Land and Resource Management Planning (LRMP) was implemented by the British Columbia Government (Canada) in the mid-1990s in the Great Bear Rainforest in order to establish a multiparty land-use planning system. The aim was to "maintain the ecological integrity of terrestrial, marine and freshwater ecosystems and achieve high levels of human well-being". The steps described in the programme included: protect old-growth forests, maintain forest structure at the stand level, protect threatened and endangered species and ecosystems, protect wetlands and apply adaptive management. MacKinnon (2008) highlighted that the main limitation of this program was the social and economic aspects related to the lack of orientation to improve human well-being.

The Great Lakes - Canada and United States

A Remedial Action Plan (RAP) was created during the Great Lakes Water Quality Agreement that implemented ecosystem-based management. The transition, according to the authors, from "a narrow to a broader approach " was not easy because it required the cooperation of both the Canadian and American governments. This meant different cultural, political and regulatory perspectives were involved with regards to the lakes. Hartig et al. (1998) described eight principles required to make the implementation of ecosystem-based management efficacious: "broad-based stakeholder involvement; commitment of top leaders; agreement on information needs and interpretation; action planning within a strategic framework; human resource development; results and indicators to measure progress; systematic review and feedback; and stakeholder satisfaction".

Elwha Dam under deconstruction

Dam removal in the Pacific Northwest

The Elwha dam removal in Washington state is the largest dam removal project in the United States. Not only was it blocking several species of salmon from reaching their natural habitat, it also had millions of tons of sediment built up behind it.

Scallop aquaculture in Sechura Bay, Peru

Peruvian Bay Scallop is grown in the benthic environment. Intensity of the fishery has caused concern over recent years and there has been a shift to more of an environmental management scheme. They are now using food web models to assess the current situation and to calibrate the stocking levels that are needed. The impacts of the scallops on the ecosystem and on other species are now being taken into account as to limit phytoplankton blooms, overstocking, diseases and overconsumption in a given year. This study is proposed to help guide both fisherman and managers in their goal of providing long-term success for the fishery as well as the ecosystem they are utilizing.

Enhancing lake fish populations - Germany

Scientists and numerous angling clubs have collaborated in a large-scale set of whole-lake experiments (20 gravel pit lakes monitored over a period of six years) to assess the outcomes of ecosystem-based habitat enhancement compared to alternative management practices in fisheries. In some of the lakes, additional shallow water zones were created. In other lakes, coarse wood bundles were added to enhance structural diversity. Other study lakes were stocked with five fish species of interest to fisheries. Unmanipulated lakes served as controls to allow for a comprehensive before-after-control-impact study design. The study was based on a sample of more than 150,000 fish. Radinger et al. (2023) found that fish stocking was ineffectual, whereas ecosystem-based habitat management through creating shallow zones increased fish abundance, especially that of juvenile fish. The authors argue that restoring ecological processes and key habitats have a larger potential to meet conservation goals than narrow, species-focused actions.