Gulf Marine Life Recovery
The marine life of the Gulf may take a long time to recover from the oil.
Joshua Wiegert |
A past installment of Conservation Corner focused on what is undoubtedly the largest environmental disaster in American history, and quite possibly in human history. While some events have involved larger amounts of damage, none have ever captured the attention of the world as the Gulf oil disaster. In early August, we heard news that this disaster may be, for all intents and purposes, over. The well was capped, and spotter planes began to report that “no oil slicks were found.”
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Filter feeding organisms often ingest oil, mistaking it for food. These organisms form the base of the food chain.
Large shoals of small baitfishes may become severely coated in oil, often suffocating as oil coats their gill rakers. These fish in turn become food for larger fish, which ingest oil and its byproducts.
Unfortunately, this is far from the truth. The oil disaster doesn't end just because it’s stopped – it only ends when it’s cleaned up. Picking up the mug doesn't mean your coffee spill is over.
We can't ignore one of the most obvious problems that the Gulf oil disaster has brought. Countless people have lost their livelihood, and the domino effect is bound to take many more, particularly with the present-day economy.
Of course, an area of concern for us as aquarists is in the marine life that may have been affected. Unfortunately, I cannot say that the marine life is going to recover well. Many planktivores are ingesting oil and it’s quite toxic. It is particularly problematic for filter feeding organisms, which include many of the smaller fishes in the region, as well as many marine invertebrates. The filter feeders bring water over their gills and use their gills to “sift” food out, like a sieve. Unfortunately, they're sifting oil, which coats their gills and suffocates them. Much of the zooplankton are also ingesting oil – organisms such as copepods, krill and others. Not only does this kill them, but it also means that those organisms that eat zooplankton are eating oil. This creates a “bottom-up effect,” rippling through the food chain.
This “bottom-up effect” can be quite far-reaching. Fishes that have been slightly poisoned can travel quite a far distance. Indeed, oil poisoning may not even kill them directly. It may have the effect of just slowing them down or knocking them off balance, which means they're more likely to be eaten by predators. It’s an ironic ecological fact that sometimes the predators that are picking off the weakest organisms get the short end of the stick for helping evolution along.
It’s not just oil ingestion that can cause problems. Inhalation of oil fumes, either by air breathing marine organisms or absorption through gills, can cause severe respiratory damage. The oil can cause chemical burns and severe skin irritation should it coat an animal. And, it’s not just the oil that causes problems, but also the dispersant chemicals used in the cleanup – some of which appear to be as nasty as the oil itself.
We have all seen the images of various marine animals covered and coated with oil, ranging from shore birds to sea turtles. While many of these animals were found, cleaned and rescued – many more were not. I've seen no reliable estimates on the population loss of these organisms, and doubt that anyone can ever estimate the numbers. One news report on sea turtles specified that only about 10 percent of turtles found coated in oil survived, and this is only among those found (how many simply sink out at sea, or wash up somewhere else?). Needless to say, many of these species represent species in various states of peril, ranging from “at-risk” to “endangered.” All species of sea turtles are protected as threatened or endangered, and five species are found in the Gulf of Mexico. The Kemp’s Ridley sea turtle is critically endangered, and one of the species most commonly depicted. Sadly, the oil spill happened during nesting season, with oiled turtles appearing on some beaches, attempting to lay their eggs amidst clean up. Similarly, hatching turtles have been forced to swim through oil soaked waters in some areas. Hatchlings are far more sensitive than adults.
One of the groups of organisms getting very little media attention is the marine mammals – dolphins and whales. These organisms must surface to breath, and in doing so, are often coated in oil. Numerous dead dolphins have been found, presumably affected by the oil. Dolphins have also been observed acting erratically throughout the area, as well as appearing severely malnourished.
The Gulf of Mexico is one of the most vital spawning areas in the Atlantic Ocean system for numerous fishes. As any aquarist knows, fry and eggs are incredibly sensitive. These incredibly delicate larvae are having to swim through a toxic soup of oil and dispersant, with lethal consequences. These include such important game fish as swordfish and tarpon, as well as smaller anchovies, angelfish, and other fishes. It may very well be that at least one year of spawning will be lost, and this includes more than just fishes. Populations of short lived species, including plankton and invertebrates, may be forever influenced.
There are some small bits of good news emerging as well, and we shouldn't ignore them in the heap of bad. Many media outlets are focusing on the fact that oil continues to seep from the sea bed, and pointing out that it has, essentially, always done so. Oil is actually an excellent food source for certain types of bacteria. It turns out that, because oil has always been present as a food source in the Gulf waters, these bacteria naturally occur. The Infallibility of Microbes Principle states, more or less, that if something is edible, a microbe will find a way to eat it, eventually. These bacteria are going to help break down whatever oil remains in the region. Think about what happens if you pour a little extra ammonia into an aquarium – green water, which depletes the ammonia. Same idea.
The downside? While there may be plenty of oil for bacteria to eat, they need other nutrients to survive – ironically, a lot of these nutrients get dumped into the Gulf via the Mississippi River delta (a topic we'll discuss in a couple months). It could be an interesting effect if the Gulf winds up a little cleaner from the oil spill. In the meanwhile, it may be necessary to fertilize certain areas of the Gulf in order to get oil biodegraded. Further, all that oil that is being broken down is being broken down into – you guessed it – carbon dioxide, a major greenhouse gas. Next month, we'll look at the effect of carbon dioxide on the ocean.
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Gulf Marine Life Recovery