Children of Morrow, part 2
Apr. 12th, 2011 03:12 pm![[personal profile]](https://www.dreamwidth.org/img/silk/identity/user.png){kind=small}
marinessOver at Tor.com, the commenters have shocked me by displaying an unexpected interest in mollusk ecology.
Unfortunately, I deleted my original four paragraphs on the subject since they were boring (really!) and focused on Florida and Chesapeake Bay issues rather than the California ecology H.M. Hoover is talking about. But, given the interest, I decided to try to answer the question anyway...
...and as so often happens, found myself writing far more than I originally intended to (or originally did, since I'm fairly sure my original paragraphs did not go into bioaccumulation), far too much for a comment on Tor.com. So, I'm putting it over here, under a cut for those not interested in mollusks, ecology, Chesapeake Bay oysters, and dinoflagellates, which is apparently fewer of you than I thought.
Rant warning!
On page 41, Hoover writes:
"In the tidal edge were clams, tiny gnarled oysters and huge scavenger snails. Inured to the poison of man's pollutants, adapting to limited oxygen, the shellfish had thrived on a world turned to garbage. In their systems through countless generations the chemicals had been condensed, refined and altered to forms never before known."
In a word, no.
Mollusks certainly look tough, I admit. And many have been spotted in areas that look just awful to human eyes – filled with muck or seaweed or general crap. We've all seen grubby looking clam like things clinging to distinctly unpleasant seeming places.
But here's the small problem: as it turns out, mollusks are, for the most part, niche organisms. Each species requires very specific salinity levels, temperature ranges, food sources, and, above all, oxygen levels. Very specific: torrential rains, for instance, can actually kill marine oyster beds by altering the nearby salinity levels for a comparatively brief period. And to greatly oversimplify a not so small problem with Hoover's argument, the oceans get a significant amount of their oxygen from the atmosphere. If the oxygen levels in the atmosphere go down, so too will the levels of dissolved oxygen in the ocean. (Chemists are about to interrupt me here, pointing out that dissolved oxygen levels are also dependent on other factors – temperatures, pressures, and so forth, which is also true and not something Hoover considers either, so I'll be skipping that for now.)
In fact, oysters in particular are so hypersensitive to ecological changes that they are usually used as ecological signifiers of environmental damage; crashing oyster harvests in Chesapeake Bay, for instance, helped demonstrate the effects of nutrient outflow and pollutants. Biologists actually use oysters to help find point sources of pollution (by which I mean, pollution coming from a specific source.) Meanwhile, many (not all) crustaceans are highly specialized eaters; if you can eat something no one else is eating, that improves your chances of surviving – unless you get to the point where you can't eat anything else, especially if your food source disappears. They, too, would have problems surviving an ecological collapse.
Hoover's embrace of the popular "nasty little invertebrates can survive most anything" approach is problematic not just because it's wrong, but because it perpetuates the belief that we need to focus protective efforts on large, cute creatures, rather than the small, not cute creatures that clean our air and water, pollinate our plants, and feed us or the things we feed on. And it's all the more problematic because it appears in an text focusing on ecological collapse, ignoring that while the ecology can generally survive with the loss of a large, charismatic fauna (like a dolphin) it's going to have a lot more problems surviving without its ugly little oysters.
Why? Because before you start feeling too sorry for the oysters, bear in mind that they can fight back, at least a little: oysters also work to clean water (and they're pretty effective at it.) And other creatures – including some of those crustaceans – need to eat them.
The second part of Hoover's statement is a little less inaccurate, although she does not quite have the process correct. Clams and oysters and snails, like other animals, bioaccumulate toxins. This happens through a multistep process that works more or less like this: bacteria pick up a toxin in the water; a diatom eats several of these bacteria, concentrating the toxin in a single cell; something else eats that diatom, and several others, further concentrating the toxin, and so on up to the point where some tuna (generally at the top of the food chain) can have high levels indeed, since although most animals (including humans) can eliminate a portion of these toxins, few animals can eliminate them all.
But, and this is key, in general, it's not the mollusks that are condensing, refining and altering chemicals. Which is not to say that isn't happening in the ocean: it is, all the time, often by amazing critters called dinoflagellates, among the most awesome single celled creatures ever. (You will find that biologists have no consensus on who should be in the most awesome single celled creatures group, but I think that dinoflagellates definitely qualify.) Some of them happily swim in the sea, some are parasites, and a large number of really fascinating ones form symbiotic relationships with corals, helping to build coral reefs. And some of them produce toxins that pop up in shellfish and make you sick or cause paralysis and death. (Yay!)
Many of those toxin producing dinoflagellates also happen to be photosynthetic: in other words, they produce oxygen. So while I'm fine with saying that the dinoflagellates, who do produce neurotoxins now, might have produced a new toxin in sufficient quantities to give humans telepathy after bioaccumulation by oysters, if they were producing that many toxins, the oxygen levels in the air (not the water) should be higher than what Hoover portrays. (Algal blooms by dinoflagellates – the sort that cause neurotoxin exposures and issues – can lower oxygen levels in the water, which again, would kill the oysters.
And this is just page 41.
********
I should note, by the way, that the other reason I originally deleted this stuff is that it's been a few years since I studied mollusks or their ecology in any depth (which, many marine biologists would assure you, wasn't much depth to begin with) and mollusks were never my sort of thing. In addition, this rant contains several of what could be kindly called "generalizations," and biology always, but always, has exceptions to the generalizations. (I feel particularly bad about making such broad comments about mollusks, a very large group with a lot of diversity that I didn't go into.) In other words, don't quote me on this stuff. Except for the part about needing to focus on the small parts of the ecosystem as well, something I'll be readdressing in an upcoming fiction story appearing sometime in May.
Unfortunately, I deleted my original four paragraphs on the subject since they were boring (really!) and focused on Florida and Chesapeake Bay issues rather than the California ecology H.M. Hoover is talking about. But, given the interest, I decided to try to answer the question anyway...
...and as so often happens, found myself writing far more than I originally intended to (or originally did, since I'm fairly sure my original paragraphs did not go into bioaccumulation), far too much for a comment on Tor.com. So, I'm putting it over here, under a cut for those not interested in mollusks, ecology, Chesapeake Bay oysters, and dinoflagellates, which is apparently fewer of you than I thought.
Rant warning!
On page 41, Hoover writes:
"In the tidal edge were clams, tiny gnarled oysters and huge scavenger snails. Inured to the poison of man's pollutants, adapting to limited oxygen, the shellfish had thrived on a world turned to garbage. In their systems through countless generations the chemicals had been condensed, refined and altered to forms never before known."
In a word, no.
Mollusks certainly look tough, I admit. And many have been spotted in areas that look just awful to human eyes – filled with muck or seaweed or general crap. We've all seen grubby looking clam like things clinging to distinctly unpleasant seeming places.
But here's the small problem: as it turns out, mollusks are, for the most part, niche organisms. Each species requires very specific salinity levels, temperature ranges, food sources, and, above all, oxygen levels. Very specific: torrential rains, for instance, can actually kill marine oyster beds by altering the nearby salinity levels for a comparatively brief period. And to greatly oversimplify a not so small problem with Hoover's argument, the oceans get a significant amount of their oxygen from the atmosphere. If the oxygen levels in the atmosphere go down, so too will the levels of dissolved oxygen in the ocean. (Chemists are about to interrupt me here, pointing out that dissolved oxygen levels are also dependent on other factors – temperatures, pressures, and so forth, which is also true and not something Hoover considers either, so I'll be skipping that for now.)
In fact, oysters in particular are so hypersensitive to ecological changes that they are usually used as ecological signifiers of environmental damage; crashing oyster harvests in Chesapeake Bay, for instance, helped demonstrate the effects of nutrient outflow and pollutants. Biologists actually use oysters to help find point sources of pollution (by which I mean, pollution coming from a specific source.) Meanwhile, many (not all) crustaceans are highly specialized eaters; if you can eat something no one else is eating, that improves your chances of surviving – unless you get to the point where you can't eat anything else, especially if your food source disappears. They, too, would have problems surviving an ecological collapse.
Hoover's embrace of the popular "nasty little invertebrates can survive most anything" approach is problematic not just because it's wrong, but because it perpetuates the belief that we need to focus protective efforts on large, cute creatures, rather than the small, not cute creatures that clean our air and water, pollinate our plants, and feed us or the things we feed on. And it's all the more problematic because it appears in an text focusing on ecological collapse, ignoring that while the ecology can generally survive with the loss of a large, charismatic fauna (like a dolphin) it's going to have a lot more problems surviving without its ugly little oysters.
Why? Because before you start feeling too sorry for the oysters, bear in mind that they can fight back, at least a little: oysters also work to clean water (and they're pretty effective at it.) And other creatures – including some of those crustaceans – need to eat them.
The second part of Hoover's statement is a little less inaccurate, although she does not quite have the process correct. Clams and oysters and snails, like other animals, bioaccumulate toxins. This happens through a multistep process that works more or less like this: bacteria pick up a toxin in the water; a diatom eats several of these bacteria, concentrating the toxin in a single cell; something else eats that diatom, and several others, further concentrating the toxin, and so on up to the point where some tuna (generally at the top of the food chain) can have high levels indeed, since although most animals (including humans) can eliminate a portion of these toxins, few animals can eliminate them all.
But, and this is key, in general, it's not the mollusks that are condensing, refining and altering chemicals. Which is not to say that isn't happening in the ocean: it is, all the time, often by amazing critters called dinoflagellates, among the most awesome single celled creatures ever. (You will find that biologists have no consensus on who should be in the most awesome single celled creatures group, but I think that dinoflagellates definitely qualify.) Some of them happily swim in the sea, some are parasites, and a large number of really fascinating ones form symbiotic relationships with corals, helping to build coral reefs. And some of them produce toxins that pop up in shellfish and make you sick or cause paralysis and death. (Yay!)
Many of those toxin producing dinoflagellates also happen to be photosynthetic: in other words, they produce oxygen. So while I'm fine with saying that the dinoflagellates, who do produce neurotoxins now, might have produced a new toxin in sufficient quantities to give humans telepathy after bioaccumulation by oysters, if they were producing that many toxins, the oxygen levels in the air (not the water) should be higher than what Hoover portrays. (Algal blooms by dinoflagellates – the sort that cause neurotoxin exposures and issues – can lower oxygen levels in the water, which again, would kill the oysters.
And this is just page 41.
********
I should note, by the way, that the other reason I originally deleted this stuff is that it's been a few years since I studied mollusks or their ecology in any depth (which, many marine biologists would assure you, wasn't much depth to begin with) and mollusks were never my sort of thing. In addition, this rant contains several of what could be kindly called "generalizations," and biology always, but always, has exceptions to the generalizations. (I feel particularly bad about making such broad comments about mollusks, a very large group with a lot of diversity that I didn't go into.) In other words, don't quote me on this stuff. Except for the part about needing to focus on the small parts of the ecosystem as well, something I'll be readdressing in an upcoming fiction story appearing sometime in May.