Selected tags: Ecosystems

Managing for a Resilient Ocean

Good science should always guide policy.  In the ocean, policy reflects decades of scientific work on single species and on single endpoints, like water quality.  However, it is now clear that ocean ecosystems are more than the sum of their parts, and policy needs to catch up to this new scientific understanding.

Of course, we must continue to protect the aspects of ocean ecosystems that we value the most.  Fisheries need catch limits to keep stocks at sustainable levels.  Pollutants need caps to keep waters fishable and swimmable.  Forestry and farming need best practices and standards to keep estuaries healthy.  But it turns out that ocean ecosystems have tipping points – ecological thresholds beyond which they undergo dramatic changes.

Healthy and resilient ocean ecosystems function similar to the United States government’s system of checks and balances—different species do similar things but in slightly different ways, which help keep these systems both interconnected and even-keeled. However, when we reduce species populations so much they can no longer do their part, we alter the natural balance of the system, which can have grave effects.

Luxuriant kelp forests that support marine mammals and a myriad of other species provide us with various ecosystem services like seafood, agar (sugar made from kelp), recreation, and sheltering the coastline from waves. However, these habitats can turn to rocky barrens very rapidly when they reach their tipping points. We witnessed this in the 1800s when fur hunting became prevalent—decreasing the sea otter population. With fewer sea otter to consume urchins, urchins became overabundant, overgrazing the kelp and causing forests to disappear.

Fortunately, science is providing insights into the factors that make ocean ecosystems more capable of resisting these kinds of changes, and more able to bounce back when they are damaged; in other words, the attributes that make some systems more resilient than others.  Having lots of species with different ecological jobs (biodiversity and niches) is very important, as is having several species doing the same job but in slightly different ways (functional redundancy).  Lots of genetic diversity within species and populations is important as well.  It's a little like rocket science: rockets are complex systems that are made more robust and resilient (i.e., less likely to blow up) by building in redundant subsystems.  Nature has done that one better by building in even more diversity, allowing coral reefs for example to recover from hurricanes and even volcanic eruptions that devastate human communities.

In an ocean in which the temperature, pH, currents, weather, and human uses are changing, it makes much more sense to manage for resilient ecosystems than manage for maximum sustainable yield of one species or another.  Who knows what the next big impact to the ocean will be?  We need to increase resiliency so that no matter what, ocean ecosystems can persist and continue to provide the many valuable ecosystem services upon which we depend.  Our new paper draws on the science of ecosystem resilience and lays out a policy framework for achieving this goal.

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Finding the Ecological Cliff and Staying Away from It: Thresholds for Sustainability

In “The Tipping Point: How Little Things Can Make a Big Difference,” author and journalist, Malcolm Gladwell explains how sociological changes often happen very quickly and unexpectedly.   He describes a tipping point as “the moment of critical mass, the threshold, the boiling point.”

It turns out that many natural ecosystems have tipping points too, called ecological thresholds.  Healthy ocean ecosystems can resist change, exist in alternative states and recover from storms, earthquakes, volcanic eruptions – and even from human activities like pollution and fishing.  Having more than one species that do similar things but in slightly different ways helps ecosystems stay healthy; i.e., makes them resilient.  But when we reduce species so much that they can't play their ecological roles or when we stress the system too much, these ecosystems can reach a tipping point and change rapidly from beautiful, productive systems to damaged systems that are incapable of creating the wonders and benefits they once produced. Read More »

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Ocean Conservation Should not be a Partisan Issue

Stetson Bank Coral and Sponges

Stetson Bank Coral and Sponges. Photo credit: Frank and Joyce Burek

No matter what happens at the polls today, the ocean and the fish that live in it will still require our attention and conservation efforts. With all the politics and rhetoric circulating throughout the media, the fact that oceans and other vital ecosystems provide invaluable resources and benefits to the billions of people on this planet tends to go unnoticed. Even worse, there is a tendency to paint the environment as a partisan issue, when regardless of your political beliefs—ensuring we have a healthy natural world is essential to your survival and happiness for the future.

The oceans cover 71% of the Earth’s surface and contain 97% of the world’s water. An estimated 20,000 species of marine fish swim beneath the largely unexplored waters, along with complex plant and animal life including coral reefs, sea grasses, whales and sharks. Billions of people globally depend on fish as their primary source of protein, and the economic value of fishing for their livelihood. Many of these people live in poor, undeveloped countries and will rely more heavily on the ocean as populations increase and global warming impacts their ability to cultivate food on land. The reality of our global dependence on the ecosystem services that the ocean provides becomes more evident with studies such one which recently came out in Science, citing that 80% of the world’s un-assessed fisheries are in worse shape than previously thought. But there is hope if we act now to align the right incentives and increase the economic value of fisheries, while putting fishermen at the forefront of conservation.  Ensuring that the world’s fish stocks are replenished is a human imperative, not a political talking point. Read More »

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“Red Herrings” in the Gulf of Mexico – Part 4: Persistent Effects?

This is the last post in a four part series discussing the ongoing – and "cascading" – effects in the Gulf, not from "oil," but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

Once the more easily processed materials and their breakdown products have completed their complicated journeys through the Gulf ecosystems, that still leaves the toxins that don’t break down easily, both the polycyclic aromatic hydrocarbons (PAHs) and metals like arsenic that are associated with drilling accidents. By some estimates, as much as a quarter of the total volume of these toxins might end up back on the sea floor, and subjected to processing – and reprocessing – by sediment-eating "infaunal" invertebrates (worms and such), which are prey for bottom-feeding fishes and crustaceans. The same applies to marshes and beaches — foraging grounds for many sought-after fishes — as well as protected species, like migrating shorebirds.


These relationships provide re-entry points for toxins back into food webs that sustain seafood production.

It could be many years before those chemicals wend their way – much more slowly, and through different pathways – through both the ecological systems of the Gulf and their human counterparts.

The pathways for many of these longer-lived toxins will also be altered as human uses resume. Shrimp trawling, for instance, will stir up sediments, potentially exacerbating the impacts of both toxicants and oxygen-demanding substances.

Again and in conclusion, some elements of the complex ecology of the Gulf of Mexico may well get off scot-free from the disaster. But many others will be heavily impaired, at least for some time. Taken together, there will be a significant total effect on the ecological systems and on the productivity and safety of seafood from the Gulf, significant human population impacts are expected, and those impacts must be remediated.

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“Red Herrings” in the Gulf of Mexico – Part 1: It Ain’t the Oil

This is the first post in a four part series discussing the ongoing – and “cascading” – effects in the Gulf, not from oil, but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

In recent weeks, nearly every discussion about the BP Oil Disaster in the Gulf of Mexico has focused on the question: “how much of the oil from the broken well is left in the Gulf?” 

The answer is simple:  “None – it ain’t the oil, stupid!”    

For some time now,  the problem hasn’t been the oil in the Gulf,  it’s the complicated series of impacts caused by the diverse substances that made up the oil as they are degraded in stages, both biologically and chemically. Each step along the way – and even the final breakdown products – poses important threats to a different suite of living things.  The total damage done by this complex array of shifting impacts on the sensitive ecosystems  and the people of the Gulf remains largely unknown.


Sure, some elements of the complex ecology of the Gulf of Mexico may get off scot-free from the disaster.  But many others have been or will be heavily impaired, at least for some time.  Taken together, there will be a significant total effect on the ecological systems of the Gulf, including the productivity and safety  of seafood, and significant  bottom-line impacts will be felt  on human health and social and economic well-being. 

Oil or Not Oil?

From the beginning of the disaster back in April, as “Gulf Light Sweet Crude” oil spewed  into the depths of the Gulf, the components of that oil – a “toxic soup” of hundreds of different chemicals – have been subjected to intense physical, chemical and biological sorting and processing, and to transportation by currents both towards and away from shore. 

This is an underwater look at one of the oil plumes in the Gulf of Mexico in late May. Click to watch the video.

By the time the well was capped in mid-July, a significant amount  of the approximately 200,000,000 gallons of liquid flowing from the broken well made it to the surface as recognizable oil.  But from the very beginning, the various “toxic soup” ingredients have followed radically different pathways through the complex oceanographic and living systems of the Gulf, spreading and being processed in different directions at different depths, and at different rates.

It is clear that all layers of the sea in a large zone around the well have been exposed, from bottom to top, as the spreading and rising cone (or “plume”) of oil-based materials spewed from the well. In contrast to a more typical oil spill on the water’s surface, where the transport and ecological fate of oil components are well-known, there are still many unknowns related to how the various chemicals have moved and are breaking down underwater, including the biochemical pathways and timetables.  Intense scientific investigation and complicated modeling are necessary before these complex relationships can be understood fully.

The addition of dispersants, both at the bottom and the top of the water column, has further altered the chemicals’ pathways through the ecosystem,  likely lessening some kinds of impacts and exacerbating others.It may well turn out that chemicals derived from oil spread over a much larger area because of the addition of dispersants, both at the bottom and the top.  The final accounting of the ecological and human winners and losers has yet to be made.

At the end of the day, the complex set of effects on the living systems of the Gulf from the oil and its chemical components will be understood, more or less.  The impacts on the human populations will be estimated, if not fully understood.  It is grossly premature to declare victory, though, until we understand the ways in which the basic fabric of the ecosystems of the Gulf has been altered, and what might be required to restore its weave.

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Louisiana Oil Spill to Seriously Impact Marine Life and Fishing Communities in the Gulf; Federal Government Must Act Swiftly

NASA satellite view of the Louisiana coastline showing the oil spill creeping toward the Mississippi Delta.

NASA satellite view of the Louisiana coastline showing the oil spill creeping toward the Mississippi Delta.

The ocean ecosystems and fishing communities in the Gulf of Mexico face potentially catastrophic impacts as a result of the 5,000 barrels of oil a day spewing out of the sub-seabed and into the waters off the coast of Louisiana. Oil moving throughout vast expanses of Gulf waters and ocean habitat and coming ashore on the massive Gulf Coast wetlands directly threatens not just the reef fish, oysters, crabs and shrimp that actually live there, but also many other species that use the reefs, marshes and other wetlands as nurseries, or that depend upon them for prey which lives or develops there.

The beaches that are likely to be coated with oil also provide important feeding grounds for shorebirds and fish alike, and essential nesting areas for sea turtles. In addition, a large number of ocean species release larvae to drift with the currents in near-surface waters — exactly where the oil currently is — in their most vulnerable life stages.

Together, a huge fraction of the fish production in the region is at risk – a body blow both to marine ecosystems and the multi-billion dollar coastal industries tied to commercial fishing and seafood, and sport fisheries and recreation. It is especially sad that this catastrophe threatens the fishing communities of the Gulf that have become national leaders in transforming oceans fisheries to models of sustainability. EDF calls on the federal government to act swiftly to minimize preventable damage, but also with compassion to bring aid and assistance to already-reeling coastal communities.

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