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Topic Name: Resilience in Coastal Marine Ecosystems highlights ecosystem-based management of coastal marine areas

Category: Environmental engineering

Research persons: Simon A. Levin, Jane Lubchenco

Location: American Institute of Biological Sciences, United States

Details

The January 2008 issue of BioScience includes a special section entitled “Managing for Resilience in Coastal Marine Ecosystems.” The four articles in the section highlight different aspects of attempts to incorporate modern concepts from mathematical ecology into ecosystem-based management of coastal marine areas.

Appreciation of the economic importance of services that marine ecosystems provide has grown in recent years, as has the awareness of those ecosystems’ imperiled state and their susceptibility to sudden ecological shifts. To understand how to sustain these valuable ecosystem services in the face of overfishing, habitat destruction, and pollution, among other challenges, researchers need to know how marine ecosystems often continue to function despite disturbances--in other words, they need to know what makes these systems resilient when they are subjected to externally imposed changes.

The introductory article by Simon A. Levin and Jane Lubchenco provides an overview of the theoretical approach adopted by the authors of the other articles in the section. The theoretical constructs suggest a number of ways that management for resilience might be improved. Levin and Lubchenco emphasize that marine ecosystems are usefully seen as complex and adaptive. Interactions among the “agents” of these systems at small scales shape whole-system dynamics, which in turn affect the smaller scales.

The introduction is followed by an article that summarizes lessons learned about recovery, reversibility, and resistance to change of marine ecosystems. Authors Stephen R. Palumbi, Karen L. McLeod, and Daniel Grünbaum hold that these three components, ideally studied together, are key elements of resilience. They stress the need to analyze long-term population data to recognize trends in species’ occurrence that could foretell far-reaching disturbances.

Gretchen E. Hofmann and Steven D. Gaines next discuss emerging technologies that can be used to understand natural variability in marine ecosystems, which is essential to managing marine ecosystems for resilience. The technologies they discuss range from space-based monitoring to tagging of large pelagic organisms to the use of genomics to assess the distribution, abundance, and health of marine life.

In the last article of the section, Mary Ruckelshaus, Terrie Klinger, Nancy Knowlton, and Douglas P. DeMaster describe practical experiences and scientific and governance challenges arising from attempts to use the concept of resilience in coastal marine management. Although comprehensive case studies of ecosystem-based management of marine areas do not yet exist, Ruckelshaus and her colleagues detail challenges for fisheries and conservation efforts in the Southern Ocean, the Bering Sea/Aleutian Islands, Australia’s Great Barrier Reef, and coastal California that could be--and in some cases are being--alleviated by ecosystem-based management approaches.

Note for Coastal ecosystem

Coastal ecosystems are considered to be one of the most productive ecosystems on Earth. They can be referred to as “the intertidal and subtidal areas above continental shelf (to a depth of 200m) and adjacent land area up to 100 km inland from the coast”. Because of their diversity, which includes mangroves, coral reefs, seagrass beds, barrier islands, and tidal wetlands, coastal ecosystems have an extraordinary amount of biodiversity. With 39% percent of the worlds population living within 100 km of the sea, human impacts are felt even more harshly in coastal ecosystems.

Note for Marine ecosystem

Marine ecosystems are part of the earth's aquatic ecosystem. They include oceans, estuaries, salt marshes, lagoons, some tropical ecosystems, such as mangrove forests and coral reefs, rocky, subtidal ecosystems, and shores. The main difference between this and other aquatic ecosystems is its salt content larger than that of fresh water.

Note for Overfishing

Overfishing occurs when fishing activities reduce fish stocks below an acceptable level. This can occur in any body of water from a pond to the oceans. More precise biological and bioeconomic terms define 'acceptable level'.
Biological overfishing occurs when fishing mortality has reached a level where the stock biomass has negative marginal growth (slowing down biomass growth), as indicated by the red area in the figure. (Fish are being taken out of the water so quickly that the replenishment of stock by breeding slows down. If the replenishment continues to slow down for long enough, replenishment will go into reverse and the population will decrease.)
Economic or bioeconomic overfishing additionally considers the cost of fishing and defines overfishing as a situation of negative marginal growth of resource rent. (Fish are being taken out of the water so quickly that the growth in the profitability of fishing slows down. If this continues for long enough, profitability will decrease.)
A more dynamic definition of economic overfishing may also include a relevant discount rate and present value of flow of resource rent over all future catches.
Ultimately overfishing may lead to resource depletion in cases of subsidised fishing, low biological growth rates and critical low biomass levels (e.g. by critical depensation growth properties).
The ability of the fisheries to naturally recover also depends on whether the conditions of the ecosystems are suitable for population growth. Dramatic changes in species composition may establish other equilibrium energy flows that involve other species compositions than had been present before (ecosystem shift). (For example: remove nearly all the trout, the carp take over and make it near impossible for the trout to re-establish a breeding population.)

Note for Habitat destruction

Habitat destruction is a process of land use change in which one habitat-type is removed and replaced with another habitat-type. In the process of land-use change, plants and animals which previously used the site are displaced or destroyed, reducing biodiversity. Urban Sprawl is one cause of habitat destruction. Other important causes of habitat destruction include mining, trawling, and agriculture. Habitat destruction is currently ranked as the most important cause of species extinction worldwide. It is a process of environmental change important in evolution and conservation biology. As the name implies, it describes the emergence of discontinuities (fragmentation) in an organism's preferred environment (habitat). Habitat fragmentation can be caused by geological processes that slowly alter the layout of the physical environment or by human activity such as land conversion, which can alter the environment on a much faster time scale. The former is suspected of being one of the major causes of speciation. The latter is causative in extinctions of many species.
This term, or the terms "loss of habitat" and "habitat reduction", can also be used in a wider sense including loss of habitat due to other factors, such as noise pollution.

BioScience is the monthly journal of the American Institute of Biological Sciences (AIBS). BioScience publishes commentary and peer-reviewed articles covering a wide range of biological fields, with a focus on “Organisms from Molecules to the Environment.” The journal has been published since 1964. AIBS is an umbrella organization for professional scientific societies and organizations that are involved with biology. It represents some 200 member societies and organizations with a combined membership of about 250,000.
The four articles that constitute the special section “Managing for Resilience in Coastal Marine Ecosystems” are listed below. Other research articles in the January 2008 issue of BioScience are described in a separate press release, “Insects’ “Giant Leap” Reconstructed by Founder of Sociobiology.”
Resilience, Robustness, and Marine Ecosystem-based Management
Simon A. Levin and Jane Lubchenco
Ecosystems in Action: Lessons from Marine Ecology about Recovery, Resistance, and Reversibility
Stephen R. Palumbi, Karen L. McLeod, and Daniel Grünbaum
New Tools to Meet New Challenges: Emerging Technologies for Managing Marine Ecosystems for Resilience
Gretchen E. Hofmann and Steven D. Gaines
Marine Ecosystem-based Management in Practice: Scientific and Governance Challenges
Mary Ruckelshaus, Terrie Klinger, Nancy Knowlton, and Douglas P. DeMaster