Defining Ecosystems as an Initial Step in EBM: Experts Discuss the Challenges and Implications

The Skimmer on Marine Ecosystems and Management

A basic concept in ecosystem-based management is that, when managers make decisions, they will consider the full array of natural and human elements and interactions that make up an ecosystem. By that account, a necessary initial step in EBM is for managers to define what their target ecosystem is. Is it small, involving a single bay, for example - or is it really big, encompassing a large marine ecosystem that crosses national boundaries? Does it involve only marine habitats, or does it extend upland into watersheds to account for factors like agricultural runoff that impact downstream areas?

How the target ecosystem is defined carries implications. Importantly, it affects which activities must be managed and which communities need to be engaged. It can also be strategic. If the definition is historically oriented, for example, it can help guide management toward ecosystem conditions that existed in the past, such as prior to heavy exploitation. Likewise it can consider the future by taking into account how the target ecosystem may respond and adapt over time to climate change.

In this issue, MEAM asks a few experts for their guidance on defining ecosystems and how this affects management. Their responses are below.


A. Defining ecosystems at different scales

By Stacy Jupiter

[Editor's note: Stacy Jupiter is director of the Wildlife Conservation Society (WCS) Fiji country program. WCS-Fiji and conservation partners assist management of ecosystems at a range of scales: from small locally-managed marine areas to the much larger Vatu-i-Ra Seascape area (encompassing thousands of square kilometers), as well as a "ridge-to-reef" management program that extends from mountain tops to coastal waters.]

On defining ecosystems in Fiji

For practical purposes, an ecosystem needs to be specified with appropriate boundaries in space and time for the goals and questions of a particular project or management initiative. Where the limits should be drawn depends largely on the scale of the research or management questions. If the project is focused on maintaining ecosystems, then the boundaries of a system to be managed must be big enough to include all the main processes affecting ecosystem stability at the largest scale, such as the dispersal ranges and movement patterns of the main component species, as well as the threats that impact both species and habitats.

In Fiji, while coastal and marine resource managers may be primarily concerned about mangrove, seagrass, and coral reef systems and the species they contain, we know that there is high mobility of species between marine and freshwater habitats. Research by Wetlands International-Oceania and WCS-Fiji has shown that greater than 98% of Fiji's fishes found in freshwater systems make contact with the sea at some stage in their lifecycle. These fish species are affected by disturbance throughout the length of the catchment (e.g., from land clearing, dams, and gravel extraction). Therefore to manage for these fishes, it is imperative to manage along the length of the catchment from the headwaters of streams to the reefs. Similarly, if the main focus of the project is on reducing threats to coral reef ecosystems from land-based runoff, the system under management should be bounded by the geographic range that includes both the source of the runoff and the area over which freshwater and suspended sediments are distributed in the nearshore.

Implementing these management initiatives in Fiji and many of the Pacific Islands is greatly aided by the fact that the boundaries of traditional hierarchies have included ridge-to-reef units (i.e., the Fijian vanua, the Solomons Islands puava, the Yap tabinau, the Hawaiian ahupua'a). In Pacific countries with strong legal recognition of traditional resource tenure, these decision-making bodies may reduce governance complexities, thus facilitating management across boundaries that are both ecologically and socially relevant.

Scaling up to a seascape unit, however, is more complex. While the boundaries of a seascape may be ecologically relevant for critical processes such as fish and coral larval dispersal from oceanographic currents, they can cross district, provincial and, in some cases, even national governance boundaries. Our approach in Fiji has largely been to work within traditional hierarchical units to implement EBM and then scale up these management networks across a seascape. Because we recognize that these disparate networks may not be enough to protect all critical ecosystem processes and functions, we have additionally been convening workshops with provincial planners to highlight the gaps and discuss ways to extend community-based management across habitats that are critical for providing ecosystem services to the entire seascape.

On how defining ecosystems has affected management

Marine management in Fiji works best when traditional governance boundaries are within the secure governance of a single district (tikina) and they encompass a large enough area to affect ecological processes. In Fiji, all of the traditional fisheries management areas (qoliqoli) have been legally demarcated by the Native Lands and Fisheries Commission. While indigenous Fijians do not have tenure over the sea, they have traditional resource use rights within the qoliqoli boundaries and are encouraged by the government and the Fiji Locally Managed Marine Area (FLMMA) network to develop local management rules regarding closures and gear restrictions. In Kubulau tikina, where WCS-Fiji has assisted communities to implement ecosystem-based management since 2005, the process has been largely successful because the qoliqoli is large (260 km2), which enabled the establishment of Fiji's largest marine protected area (Namena Marine Reserve, 61 km2). In other regions, such as around Yanuca Island in Beqa Lagoon, it has been more difficult to establish firm management rules or placement of closures because several of the qoliqoli are shared by communities from several tikina who are unable to agree upon the management measures.

On managing toward a particular, defined ecosystem state

We base our management recommendations to Fijian communities on measures that, if well-enforced, will allow the preservation or restoration of the important ecosystem services on which people depend. For Fijians, the most important ecosystem services are food security, water regulation, and human health.

This approach represents a critical shift in thinking about marine ecosystem management. When I joined the WCS-Fiji in 2008 and inherited management of the Fiji EBM project, the original goal of the project was to "facilitate a shift of the marine ecosystem of the Vatu-i-Ra and Great Sea Reef Seascapes back to their 'natural' state." After a thorough programmatic review, we identified that this target was unachievable given global environmental and climate change. Therefore we shifted our mission to: "preserve the functional integrity of the Vatu-i-Ra and Great Sea Reef Seascapes to sustain biodiversity, fisheries, and intact linkages between adjacent systems."

For more information: Stacy Jupiter, Wildlife Conservation Society, Suva, Fiji. E-mail: sjupiter [at] wcs.org


B. Defining a target ecosystem by what it used to be like

By Heike Lotze

[Editor's note: Heike Lotze is Canada Research Chair in Marine Renewable Resources at Dalhousie University, Canada. An historical ecologist, Lotze studies past, present, and potential future human impacts on marine species and ecosystems. With this knowledge, she informs marine resource programs on how to define their target ecosystem state - such as one that existed prior to heavy or over-exploitation by humans - then manage toward it.]

On managing toward past ecosystem conditions

Although the idea may be attractive that management can redesign or recreate how historical ecosystems looked prior to heavy exploitation - say, 50, 100 or 500 years ago - we cannot do it. Too many variables have been altered. Also, we do not know every parameter or all species interactions of historical ecosystems, and cannot control or manage each of these individual parameters.

However, we can create conditions - by reducing harmful human impacts - that may allow certain species, populations, habitats, and water quality to recover toward "former" levels of abundance, distribution, diversity, complexity, or whatever you want to measure. What "former" levels can be achieved certainly depends on the magnitude of depletion, degradation, and change, and what is possible given the new environmental or human conditions (e.g., how much coastline has been irreversibly transformed). I would try to aim for pre-heavy human impact, so probably pre-industrial levels - but essentially that is a value judgment. What does the local, regional, or global community want? If your goal is to end up with a more natural ecosystem, then you want to reduce the dominant human impacts and allow for natural controls (e.g., climate variability and species interactions) to take over again.

On factors that aid recovery of depleted populations

Since most depletions, collapses, and extinctions have been caused by more than just one human impact, the recovery often depends on more than one factor as well. Among historical recoveries, the reduction of cumulative human impacts - especially exploitation, habitat loss, and pollution - was important in 78% of recoveries, according to our findings. Every species needs a range of conditions to be met to thrive, including proper habitat, food, environmental standards (e.g., clean water, air, sediments), and a low enough mortality rate (whether natural or human caused) in order to survive. If several of these conditions have been compromised, then it needs the restoration of all of them to enable recovery.

For more information: Heike Lotze, Dalhousie University, Halifax, Nova Scotia, Canada. E-mail: hlotze [at] dal.ca


C. How the definition of a target ecosystem informs current and future management

By Steve Gittings

[Editor's note: Steve Gittings is Science Coordinator for the US Office of National Marine Sanctuaries. He facilitates research in the nation's 12 national marine sanctuaries, including how climate change is affecting species, habitats, and whole ecosystems.]

On defining ecosystem boundaries

The US National Oceanic and Atmospheric Administration has the following definition for "ecosystem":

"A geographically specified system of organisms (including humans), the environment, and the processes that control its dynamics."

Personally, I am not particularly fond of that definition because I believe it over-emphasizes geography and under-emphasizes the relationships and dependencies between species and those between species and the environment. Most of the definitions you will find in other places do not mention or imply anything about boundaries and focus more on components, the interactions between living and non-living parts, and the flow of materials and energy between these parts.

But as you can imagine, some concept of boundaries and geographic limits to ecosystems is useful when it comes to management, even if they are hard to determine in the real world and are, in fact, different from the perspective of different species that have different requirements. So rather than focusing too much on ecosystem boundaries, the Office of National Marine Sanctuaries employs the concept of ecosystem-based management - looking at all the links among living and non-living resources, rather than considering single issues in isolation. The national marine sanctuaries make decisions and take action using this approach rather than worrying too much about specific boundaries of ecosystems.

On ecosystem boundaries vs. sanctuary boundaries

Many people have recognized that sanctuary boundaries often do not coincide with ecosystem boundaries. The sanctuaries may contain ecosystems of interest, or are representative of larger ecosystems. In some cases they are limited by geo-political or practical considerations, such as they encompass pre-existing management areas or are rectangular to simplify enforcement.

In cases where changes have been made to the boundaries of national marine sanctuaries, ecosystem boundaries have been considered but have not been the sole driver of the sanctuary boundary determination. (Making changes to sanctuary boundaries is generally done as part of a review process undertaken when management plan revisions are made, or in some cases through congressional action.) When done during a management plan review, changing sanctuary boundaries involves extensive assessment of information on ecosystems and the threats they face (to judge the need for boundary changes), but also substantial evaluation of social and economic implications (such as impacts on users), and engagement of numerous sectors of the public. That being said, in each case the ecosystem is foundational as a starting point for the conversation and the primary target for biodiversity conservation. [Editor's note: A review of boundary expansion concepts for the Channel Islands National Marine Sanctuary is at http://ccma.nos.noaa.gov/products/biogeography/cinms. Another report, Examples of Ecosystem-Based Management in National Marine Sanctuaries: Moving from Theory to Practice, profiles EBM initiatives at eight national marine sanctuaries and one marine national monument in US waters:http://sanctuaries.noaa.gov/science/conservation/pdfs/nceas.pdf.]

On potentially re-defining target ecosystems in a climate-changed future

The specter of climate change should be a wake-up call for all ecosystem-based management efforts in marine systems. The best practical approach would be to become more precautionary than we currently are with regard to controlling resource extraction and inputs by humans. The goal should be to endow ecosystems with as much natural "integrity" as possible. This means actively preserving or restoring ecosystem structure and function, and their inherent spatial and temporal variability, as resolved by the ecosystem's natural evolutionary history.

But even with stronger natural resistance, we are faced with the very real possibility of having to adapt our management to deal with restructured ecosystems that are substantially different from those that the marine sanctuaries were originally intended to protect (e.g., the loss of coral reefs in areas that currently protect them). For those, our management plans will adapt accordingly. And there may even be a bright side. These altered ecosystems could offer unexpected opportunities to exploit new services, such as new local food sources, new educational programs for visitors, or chances to engage volunteers in monitoring of changes.

For more information: Steve Gittings, Office of National Marine Sanctuaries, NOAA, Silver Spring, Maryland, US. E-mail: Steve.Gittings [at] noaa.gov


BOX: Defining the Great Barrier Reef ecosystem as part of a major zoning program

By Leanne Fernandes

[Editor's note: Leanne Fernandes managed a multi-year process, the Representative Areas Program, to rezone the Great Barrier Reef Marine Park (GBRMP) nearly a decade ago. The process involved defining the park ecosystem as comprising 70 largely contiguous bioregions. Her comments here have been reprinted from MEAM 1:1, published in 2007.]

"If one is aiming for ecosystem-based management, then one needs an idea of what is intended by an ecosystem. From a management perspective, the definition needs to be politically, legally (jurisdictionally), socially, as well as ecologically sensible. This is likely to mean scientific compromise, presuming that science could give one a perfect geographical definition of an ecosystem in any one location. Of course, in as far as science is unable to offer the 'perfect' definition of ecosystem, the degree of compromise will be unknown.

"Given this umbrella, the political, jurisdictional, and social context is important. Depending on these factors, one can treat an estuary and all its components as an ecosystem for the purposes of ecosystem-based management - or a bay or a section of a continental shelf. If one's role is fisheries management, then the 'ecosystem' might be defined by the area (including habitats and communities) used by the fish being managed or by the fishers pursuing the fish. On the Great Barrier Reef, for the purposes of rezoning the entire GBRMP through the Representative Areas Program, the ecosystem was defined as the composite of all parts of the Marine Park and the World Heritage Area. This included estuaries and intertidal areas beyond the boundary of the Great Barrier Marine Protected Area (GBRMPA) but within jurisdiction of GBRMPA's management partner, the Queensland government.

"The definition of habitat and/or some kind of lower-scale 'bioregion' can help managers distinguish areas within their jurisdiction or within their definition of ecosystem. Again, from a management perspective, it is not necessarily useful to rely on a purely scientific definition of habitat or bioregion - assuming this were even available. One might first wish to consider what management objectives one aims to achieve. Water-quality management objectives, fisheries-management objectives, and biodiversity-management objectives may require different scientific, social, political, and jurisdictional factors to be considered in defining habitats or bioregions."

For Fernandes's full remarks, go to https://meam.openchannels.org/content/ask-expert-what-does-ecosystem-mean-context-ebm.

Add new comment