Author Archives: Doug Rader

The future of Galveston Bay: Implications of the oil spill

Fishing boat coming in from Galveston Bay. Photo Credit: Roy_Luck

Fishing boat coming in from Galveston Bay.
Photo Credit: Roy.Luck

Galveston Bay is a busy body of water. It carries the traffic of the Houston Ship Channel. It is a popular recreation destination for fishermen and others. It not only serves as a home to birds and large marine animals, but also as a nursery ground for many important seafood species. It is the nation’s seventh largest estuary and among them the second most important seafood producer, behind only the Chesapeake Bay.

The immediate effects of the oil spill on March 22, 2014, are visible in the oil sheens and tar balls floating in the water and the “oiled” birds and animals that crews are trying to help. But, we can’t see how this heavy marine fuel, containing toxic chemicals including polycyclic aromatic hydrocarbons (PAHs), is harming shrimp, crabs, oysters, red drum and other fish that call the waters of Galveston Bay home. This contamination can hang around for a long time. Studies from the 2010 Deepwater Horizon Oil Spill show that even in low concentrations PAHs can disrupt the development of fish and invertebrate larvae; and in high concentrations can be lethal. Recent reports of tunas susceptible to deformities from the 2010 spill attest to the potential risks long after the spill itself is gone.

The timing of this spill is bad for several key species especially important to the seafood industry and consumers. Brown shrimp have already spawned offshore, and March is the month when the young ride tides coming back inshore to settle in seagrass beds and marshes, habitats that are their nurseries – and where the water is now contaminated with oil pollution. The young are especially vulnerable from now until about May or June. Young blue crabs that settled during the winter in Galveston Bay are also in danger, as are baby fish; including Gulf menhaden, a large harvest in the region’s fishing industry and a fish that is a vital food for larger fish and other animals. Marine life in the way of the oil is dying; and those not killed are exposed to toxic chemicals that could impair their reproductive potential, and some fish that feed on worms in bottom sediments may acquire and carry toxics in their tissues. The seafood “crops” in the area could well be reduced.

Anyone who has been to Galveston Bay has seen the many dolphins are other large marine life that frequent the area and eat these other fish. As these contaminants enter Bay food chains our concern turns not only to how these animals are affected by the spill in the short term, but also to their longer-term health, and even to whether or not seafood species that live there could constitute a human health risk that must be guarded against into the future. Read More »

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60 Minutes and Cuban Reefs

Underwater photo of elk horn coral and reef fish in the Gardens of the Queen marine park in Cuba.

Elkhorn coral and reef fish in the Gardens of the Queen marine park in Cuba.

Hats off to CBS for the recent “60 Minutes” segment on the coral reefs of the “Gardens of the Queen” (Jardines de la Reina) in Cuba!

The Gardens of the Queen is a spectacular national park off the south central coast of Cuba.  EDF has had the privilege of working with Cuban scientists and resource managers in the park for several years.  Just this past November we teamed up with Cuban partners there to host an international workshop on fisheries management and marine protected areas.  In 2012 we will partner with Cuban scientists to study the benefits on fish populations from restricting most fisheries inside the park.

The 60 Minutes piece highlights the good work Cubans are doing to protect marine ecosystems and the challenges that lie ahead.  I was especially impressed with the work of CBS producer Anya Bourg to ensure that the piece was rigorous – as much as possible – in its treatment of complex scientific issues.  Explaining complicated and often subtle relationships in plain and compelling language is a real feat!

For the most part, 60 Minutes got it right.  Let me expand on two key themes from the piece, based on work we are doing with Cuban scientists to help understand the lessons from the Gardens of the Queen. Read More »

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Diving in the Jardines de la Reina – Gardens of the Queen – in Southeastern Cuba

After hundreds of dives around the Caribbean – and decades of “fish watching” – I thought there was nothing left in that part of the world to knock my socks off.  Boy, was I wrong!

Tortuga floating hotel in Los Jardines de la Reina, Cuba

Tortuga floating hotel in Los Jardines de la Reina, Cuba

I have heard for years about the wonders of the Jardines de la Reina – the Gardens of the Queen – in southeastern Cuba, and so was prepared for better-than-average diving during a recent week of exploring opportunities for scientific research in the recently declared national park.  Our base was the floating hotel, “Tortuga,” operated jointly by Cuba and the Italian company, Avalon.

I was totally unprepared for the sheer spectacle created by massive Goliath groupers, swarms of huge groupers and snappers, carpets of other reef fishes, and by the parade of sharks on every dive.  Diving with free-swimming Goliath groupers – behemoths sometimes nearly the size of Volkswagens – is a never to be forgotten experience.

Dr. Doug Rader with a Goliath grouper in Cuba

Dr. Doug Rader with a Goliath grouper in Cuba

Sharks are the calling card for the Gardens to divers from around the world: silky, Caribbean reef, blacktips, lemons and nurse sharks, plus the diving “holy grail” – whale sharks – the world’s largest sharks.  During our week, divers hailed from Lithuania, Latvia, the UK, Germany and the US.

Whale sharks, in fact, create their own microcosms as they feed on zooplankton and herrings that are also eating the zooplankton attracting schools of small tuna called bonitos that in turn attract silky sharks and seabirds in a massive feeding orgy.  Spotters find whale sharks by the birds picking up the leftovers.  The week before we were there groups of divers saw whale sharks every day.  Changing weather meant clearer water and better diving, but shifted the whale sharks away from our location – only one was sited our week, and not by us!

Caribbean reef shark

Caribbean reef shark

In addition to a variety of dives on different types of reef formations, we also spent many hours snorkeling. We examined every key habitat of the Gardens, from the nurseries formed by shallow-water mangroves and seagrass beds, to patch reefs and reef crests, and then to fore reefs and coral canyons and walls. 

Each new habitat added to a list of fishes that by week’s end numbered 124 species.  Actually, we did no night diving or snorkeling, and so missed a whole element of fish diversity which hides under coral heads during the day.  Also, I realized at the end of the trip that I had failed to notice many species because the large fishes distracted me.  Cuban scientists  in the Gardens suggested that many of the smaller fish we are used to seeing during the day in the more depleted reefs around the Caribbean are also there, but must spend more time hiding under the corals given the huge abundance of predators!  Makes sense to me.

Carpet of reef fish - school of fish

A carpet of reef fish

The one “downer” we encountered was the amazing prevalence of invasive Pacific red lionfishes, which we saw on nearly every dive and snorkel, regardless of depth, and regardless of habitat type.  While the impact of these voracious predators armed with poisonous spines remains unknown, it cannot be good to have so many on the reefs and in the shallows.  On one dive, I counted 22 lionfish and one of my colleagues counted 23.  Apparently, many foreigners like to see them, unaware of the challenge to the reef – the bellwether for a future full of changing animal populations as oceans warm and acidify – that they may represent.

All in all, our EDF team returned both awed at the beauty found in this remote location, but also energized by the potential for restoration of fish populations that a combination of proper management of marine parks and effective fisheries management represent.  Given the fact that most of these reef species have life histories that reach all the way across the continental shelf, the third piece of the puzzle, of course, must be effective coastal zone management – more about that later!

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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 3: Undersea Plumes?

This is the third 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.

It could well be that the now-notorious subsurface plumes contained –or contain – a mixture of tiny oil droplets (both from oil spewing, hot, under pressure into cold water, and then being dispersed into even smaller droplets courtesy of Corexit) and dissolved or partly dissolved lower-molecular weight materials, like BTEX (benzene, toluene, ethyl benzene and various xylenes).

Components of these plumes broke down – and are breaking down – not in one felled swoop from oil to not-oil, but through a series of breakdown pathways, while it was transported in various directions as the currents shifted over several months of the active oil disaster. These materials would have been exposed to biological processing by bacteria. Bacterial populations were low initially, but have grown exponentially through time within the plumes as they drifted.

There is no free lunch in the sea: Did bacteria "eat" the oil?

Many people are sighing in relief that the apparent explosion of mid-water bacteria have processed much of the original oil load of the system. The cascading impacts of that phenomenon – if verified – have yet to be established. Perhaps the "oil," per se, is largely gone, but the array of produced materials, and their ramifying ecological effects must be fully accounted.

Full and final processing of this huge load of oil would both demand oxygen and produce carbon dioxide. While there have been some observations of adequate oxygen presence, there has as yet been no modeling of total oxygen demand and its implications for ocean ecosystems, including some already under oxygen stress. Moreover, the sea is already being subjected to acidification from absorbed carbon dioxide (the final breakdown product where oxygen is adequate from biotic degradation of hydrocarbons).

While an "Andromeda strain" scenario is far-fetched, many questions remain. What are the likely impacts of such massive loads of both oxygen-consuming organic substances and produced carbon dioxide, on oxygen levels and acidity patterns in the depths? What will happen to this large, new and artificial, biomass of bacteria, as they respire and then decompose? How will this major perturbation of mid-water biota cascade through ocean ecosystems? All unanswered questions.

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"Red Herrings" in the Gulf of Mexico – Part 2: Key Ocean Ecosystems at Risk

This is the second 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.

I remain extremely concerned about what has happened to the out-of-sight, underwater ecosystems of the Gulf of Mexico, especially at middle depths and on the bottom. These little known but ecologically vital elements of the ocean have been heavily exposed to oil-based pollution, both rising from the bottom and sinking back down from the surface, and – at least in some places – bathed in persistent underwater toxic plumes.

Marine life in the mid-waters is so rich and profuse in places that sonar waves bounce back as a "deep scattering layer" and provides key food for many familiar, surface-diving animals, including whales, dolphins, billfishes and giant tunas. Deepwater coral reefs and other bottom dwellers have been at great risk all along, and not even the initial explorations have yet been done to assess the impacts of reefs less than twenty miles from the broken well bathing in oil-based pollution.

An actual track of a sperm whale diving through rich mid-water feeding zones (shown in green) from the northern Gulf of Mexico. Credit: Modified from Azzara, 2006.

The oil and oil-derived pollution that made it to the surface followed – and is following – one set of pathways through the Gulf ecosystem, exposing and injuring not just sea turtles and sea birds, but also near-surface marine animals and plants, large and small, and entering foodwebs through a complicated series of entry points, which we don’t yet fully understand.

Fine droplets of dispersed pollution are more likely to be adsorbed onto particulates, sinking back through the midwaters and into the abyss. The moreresistent elements, like tar balls, either float away or sink back into the abyss, and follow a different set of pathways.

The total "dump" of highly toxic oil components, including low-molecular weight aromatic hydrocarbons (known familiarly as "BTEX" – benzene, toluene, ethyl benzene and various xylenes), could have been up to 50,000,000 gallons. These are heavy-duty pollutants in their own right, including known carcinogens and reproductive toxicants, with a fair solubility in sea water. In a surface spill, pollution mostly evaporates, and the only real concern relates to emergency response workers that are exposed while on duty. In this underwater case, scientists simply do not know – yet – exactly how the massive load of pollution is being processed in the Gulf.

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