After I viewed the computer simulations forecasting the dissemination of the still spouting geyser of BP oil (from the Deep Water Horizon disaster) I nearly felt ill. Maybe I was mentally projecting ahead to the future scenario where - when I make my tuna salad sandwich- I will essentially be ingesting oil. Okay, not the direct form, but after it's passed along the ocean food chain, but we'll get to that in a bit.
First, we already know the mammoth gusher is more than five times the volume of what was originally "estimated". I will be generous here, and not intimate anyone was gaming the numbers, and especially trying to lowball them.
Second, we know that if the massive contents dumped, or blown out into the Gulf, get into the loop current, they will spread across the North Atlantic possibly reaching French shores within the year. This means massive numbers of sea species will be affected, from the phyto-plankton and zooplankton to the higher organisms that feed on them, including fish and humans.
Let's look at the ocean's food chain. It actually begins with the simplest of creatures, the bacteria. There are trillions upon trillions in the oceans and one of the main components of their diet is naturally occurring organic matter. In addition, if any unnaturally occurring organic matter, such as oil, ends up in their vicinity, they will eat that. Since more than 40 milion gallons of oil has spewed into the Gulf thus far, we can be sure that something like 10^12 bacteria are eating as much of it as they can and having a feast. We also know they are likely multiplying in numbers because of the immense size of the gusher.
The bacteria in turn will be eaten by tiny flagellates, which are in turn eat by ciliates and these then devoured by zooplankton. These microscopic sea denizens will then be ingested by the jellyfish and also regular fish.
The outline above denotes what we call the "trophic level" for the existing food chain. As consumption moves from level to level, say from the ciliates to the zooplankton, nearly 90% of the energy is lost due to waste, as well as heat dissipation.
We can see that in any scale of massive input to the oceans, the bacteria will profit enormously (as the first consumers of the unnatural oil) and this will have diastrous effects on the trophic levels. In particular, as the bacteria multiply and increase consumption proportionately in response to the massive injection of organic matter, more energy will be used by them and less will be available to pass to higher trophic levels. This means fish, shrimp, crabs and other marine animals will likely experience nutritional "die outs" as their energy supply from the lower trophic levels is dramatically diluted.
It would be like feeding a person a healthy diet and making them do the same amount of output, even as the diet is switched to bread and water. With far less energy, but the same need for energy utilization, the person or creature will pay in malnutrition.
What about the oil? Obviously, though diluted the oil will yet carry up the food chain. We already know from experiments to do with marine animal ingestion of plastics in the sea (plastic bottles, plastic bags, etc.) that components and residues of it migrate up the food chain, ending up in fish in signficant quanitities then in the organs (e.g. liver) of the humans that consume them.
The great thing is we will be able to actually quantify how much of the oil passes up the trophic levels. This will be feasible because the carbon-isotope signature of the oil is distinct from that detected in naturally occurring organic matter. Any organisms, from bacteria, to ciliates on to fish or humans will retain this signature- so the amount will be trackable over time.
Oily tuna anyone?