Beneath the Waves of the Gulf of Mexico
Author: Shari Horowitz
A variety of popular aquarium specimens inhabit the Gulf Coast of the United States, a region that has faced serious threats from both natural and man-made environmental disasters in recent years.
The Great Blue Gulf of Mexico
The Gulf of Mexico comprises a large variety of delicate and complex ecosystems, from the coastal marshes of Louisiana to the deep-water slopes, basins, and canyons of the Large Marine Ecosystem, each supporting a dizzying treasure trove of marine animals both large and small, from tiny copepods to large marine mammals. This invaluable resource has faced many challenges in the recent past: merciless hurricane seasons that buffet the coastal wetlands, the growing dead zone surrounding the outflow of the Mississippi River and choking off the aquatic life in its path, and many oil spills—including the catastrophic Deepwater Horizon oil spill of 2010.
According to the director of biological programs at the National Aquarium’s Washington, D.C. venue and shark advisor for Discovery Channel’s Shark Week, Andy Dehart, it is the combination of stressors that concerns scientists the most. Ideally the reefs might be able to bounce back from one stressor—the oil spill, for instance—if it were addressed quickly enough, but having the corals already in a weakened state can only create more problems. To more fully understand what is at stake in this resource-rich and constantly beset region, TFH recently sat down with some of the world’s foremost experts in the fauna of the Gulf.
National Wildlife Refuges
The Gulf is home to 36 National Wildlife Refuges, which range from seagrass beds to mangroves estuaries and coral reefs. These waters are home to a wide variety of fish and invertebrate species, and while the area is known more as a vacation and fishing destination than a source of aquarium specimens, some of the animals in your tank may well come from the Gulf.
A great place to view those animals firsthand is the National Aquarium’s D.C. venue. Being in the capital of the U.S., it is home to the America’s Aquatic Treasures series of exhibits featuring both freshwater and saltwater animals from around the United States, including exhibits specifically featuring Gulf species.
One exhibit features animals from the Flower Garden Banks National Marine Sanctuary, which is located about 110 miles off the coast of Texas and Louisiana.The Flower Garden Banks is significant because two of the reefs, East and West Garden Banks, feature an impressive 70- to 80-percent live coral cover.
Another exhibit is dedicated to the animals of the Florida Keys National Marine Sanctuary. The Florida Keys are a chain of about 1700 islands made notable by a large offshore coral reef and serves as one of the more popular tourist destinations in Florida.
Fishes of the Gulf
The abundance and variety of fish in the area makes the threats facing the Gulf—especially oil—quite worrisome. According to the U.S. Fish and Wildlife Service, floating oil can harm fish in several ways: by being taken up by the gills, being ingested, affecting their eggs, or changing the habitat around them.
Luckily the Reef Environmental Education Foundation (REEF), a grassroots organization of divers and marine enthusiasts of which Dehart sits on the board, has had recreational scuba divers conduct casual surveys of fish abundance in the area and has a rough idea of the baseline amount of fish in the areas in and around the Gulf. Although not scientifically rigorous, those estimates can be used for comparison to the fish abundance after events that may have an environmental impact, such as oil spills.
Some of the Gulf species featured in the exhibits are standout aquarium specimens, including a wide variety of angelfish species, beginning with a fish that is often seen as a symbol of the Caribbean: the queen angelfish Holacanthus ciliaris. There are also blue angels H. bermudensis, rock beauty H. tricolor, French angelfish Pomacanthus paru, and gray angelfish P. arcuatus.
There are a host of other interesting aquarium specimens. Porcupine puffers Diodon holocanthus are appreciated by aquarists for their entertaining behavior. Like all seahorses, the longsnout seahorse Hippocampus reidi is a favorite with children and adults alike. Neon gobies Elacatinus oceanops are facultative cleaners meaning that, while they will clean other fish in the tank, they will accept other foods as well and can therefore thrive in an aquarium setting. Sargassum triggerfish Xanthichthys ringens have fascinating personalities.
These exhibits also have some smaller and more common aquarium specimens on display, such as yellowtail damselfish Microspathodon chrysurus, blackcap basslets Gramma melacara, fairy basslets G. loreto, purple reef fish Chromis scotti,and blue chromis C. cyanea. Atlantic blue tangs Acanthurus coeruleus, Spanish hogfish Bodianus rufus, and bluehead wrasses Thalassoma bifasciatum are also common in the trade.
There are also beautiful but far more rare aquarium specimens on display. Coming from deeper waters than many other species in the trade, peppermint basslets Liopropoma rubre and high hats Pareques acuminatus can make hardy aquarium specimens. Conversely, scrawled cowfish Acanthostracion quadricornis, like all cowfishes, are challenging to keep. A finicky feeder that reaches a very large size, another difficult fish is the scribbled filefish Aluterus scriptus.
The National Aquarium’s Baltimore location used to have a fish-breeding facility that bred ornamentals such as the neon goby, but the space is currently being used for aquaculturing fish that are used for human consumption. Some incidental breeding does occur within the exhibits, however, and they do try to use captive-bred fish whenever possible—Dehart encourages hobbyists to do the same.
The stressors attacking the Gulf are having a strong impact on corals, which are generally considered to be quite vulnerable. Natural events such as hurricanes cause strong waves. Those waves can physically break corals, sometimes leading to large coral heads becoming flattened. They can also scatter coral fragments.
According to the National Oceanic and Atmospheric Administration’s (NOAA) Coral Reef Information System, if natural events were the only stress facing a reef it would most likely heal relatively quickly. However, when combined with other factors, the reef is not as resilient. For example, runoff leads to increased nutrients in the water column, which often results in increased algae growth. A slow-growing coral that has been damaged by a hurricane and is in nutrient-rich water may become covered with algae and ultimately be smothered before it can recover.
Invertebrates and Oil
When it comes to invertebrates and oil, the specific impact is hard to predict, according to NOAA. Booms—floating beams used to contain oil spills—are not as effective in coral reef habitats because the anchors used to hold them in place can physically harm corals, especially when moved about in rough weather. Floating baffles would be a more coral-friendly method for containing oil spills, but according to Dehart there may be too much oil to contain in a situation as large as this year’s deepwater spill.
Some studies show that direct exposure to a large amount of oil or long-term exposure to low levels of oil can kill corals. However, according to Husbandry Supervisor Ryan Czaja at the Florida Aquarium, other university studies have shown that oil does not affect the corals, although they are not sure why. It is thought that perhaps the mucus emitted by corals might protect them and, in the wild, the tides will also provide some relief from the oil. Nevertheless, oil is thought to have a negative impact on coral reproduction.
Given the pre-existing stressors facing corals—specifically corals in Florida—the Florida Aquarium’s Global Coral Reef Institute (GCRI) has been working to restore reefs by reintroducing corals to the wild. Parent colonies of seven species of Gulf corals (Stephanocoenia michellini [intersepta], Dichocoenia stokesii, Diploria clivosa, Montastraea cavernosa, M. annularis, Siderastrea radians, and Solenastrea bournoni) were first fragged, fixed to a cement disc, and then numbered. They were cultured for approximately six months in both in-house and open systems.
The GCRI developed the first health certificate for coral. Health certificates are required in order to return a living creature back to the wild. The health and condition of the corals were carefully monitored. Each coral was given a score, and if a given coral frag passed, it was then seeded in the wild. Quarterly monitoring on the reefs where the corals were planted was conducted to see if the corals were still thriving.
Some corals did better after being returned than others; the Dichocoenia stokesii in particular is doing well. Czaja explained that important lessons have also come from the project, such as that corals have local population genetics, which can influence where they will do best. For example, some corals do better in shaded areas while others prefer being in direct sunlight.
The corals are also being carefully monitored for disease and other health issues. The greatest concern with any restoration program is that foreign pathogens can be introduced to the reef and wreak havoc.
Czaja said that the Florida Aquarium now has plans to work with two endangered species of coral found in the Gulf, the elkhorn coral Acropora palmata and staghorn coral A. cervicornis, taking into consideration what they have learned from the first seven species.
The National Aquarium is also involved with coral propagation. They are a member of SECORE (Sexual Coral Reproduction) and have had about 200 colonies of elkhorn coral on-site since 2006. They are also working with the Coral Restoration Foundation, a non-profit organization dedicated to developing coral nurseries and reef restoration projects, on their projects dedicated to saving staghorn corals. According to Dehart, Atlantic corals are very rarely featured alone, so the National Aquarium in D.C. recently opened their Atlantic Coral Reef Exhibit.
The Big Animals
Of course, people are also concerned about the bigger, cuter animals that have become the focus of many conservation efforts. There are many threatened or endangered species living in the area, including five species of sea turtles, which in particular have come to represent the problem faced by marine life.
Oil aside, many sea turtles suffered during a particularly cold winter this year and were rescued by many of the aquariums in the southeastern U.S. The National Aquarium may take in the turtles that began rehab during the winter in order to make room for individuals that were rescued from oil-ridden waters. The aquarium already has loggerhead sea turtles Caretta caretta on display.
The Gulf also serves as a nursery for many species of sharks, which can stay in the habitat for several years at a time. So another concern is what may happen to the sharks that use the Gulf as a pupping ground. Dehart, a shark biologist, is worried about the effect the oil might have on the sharks in the area over the long term because it has not been extensively studied.
Effects of the Spill
Dehart, who started out as a hobbyist, perhaps stated it best when he said that “this is a disaster for pure aquarium folks; the wondering is tough for us.” He added that we may not know the full impact of the Deepwater Horizon spill for the next 20 years or more. In fact, the full extent of the damage caused by the Exxon Valdez oil spill, which occurred in Alaska’s Prince William Sound in 1989, is still being determined, with new data coming out to this day.
What You Can Do
As an aquarist, it is best to obtain captive-bred fish for your tank whenever possible. If you have a breeding pair of fish and you successfully raise the fry, you can also make them available to other hobbyists. If you keep corals, especially species that come from the Gulf, you can frag them and offer them to fellow aquarists as well. Minimizing the impact of the hobby on the ocean is one of the best things a hobbyist can do.
Another great way for hobbyists to help is to show off their aquariums. When people see the beauty of the ocean up close, they may be inspired to help treasure and protect the invaluable natural resource that areas like the Gulf Coast—and their resident flora and fauna—represent.
See the full article on TFH Digital http://www.tfhdigital.com/tfh/201011/#pg89