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Algal Blooms

  1. Oct 2, 2009 #1
    Can someone tell me where algal blooms occur? I'm basically interested in knowing if they're more frequent in certain latitudes (colder regions).
  2. jcsd
  3. Oct 2, 2009 #2
    Though all the causes of algal blooms are still not fully known, a common factor in all algal blooms is the presence of nutrients. The blooms will only form in nutrient-rich (colder) waters. Warm water drives oxygen levels in the water down (Charles Law), which also prevents CO2-producing species from thriving, which are required for algae to grow. In colder waters where nutrients are abundant, algal blooms rapidly multiply, depleting local nutrients significantly, while dramatically increasing Oxygen levels (Oxygen is toxic to most organisms at high concentrations).
  4. Oct 2, 2009 #3
    Could you restate that statement? This is what I got out of ti:
    Warm water --> less oxygen --> less CO2 producing species --> what about algae growing?

    From this, it sounds like warmer water should produce more algal blooms, since there are less heterotrophs (algae eaters/co2 producing species), no?
  5. Oct 2, 2009 #4


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    Heavy run-off from the torrential rains we experienced this summer flooded the cold coastal waters with nutrients and the resultant toxic algal blooms crippled our shellfish industry during a season in which clam-diggers, etc generally make most of their income. The toxic algal blooms are called "red tide" though not all the toxic organisms are red.

    Got lots of nutrients, cold water, plenty of wave-action and tides to mix the water? Perfect conditions for red tide.
  6. Oct 2, 2009 #5
    No, algae are photosynthetic eukaryotes. Therefore they actually REQUIRE CO2 to grow. In areas where there are lots of heterotrophs, CO2 goes up through respiration, which is good for the algae. CO2+H20+sunlight=>C6H12O6+O2.

    Warm water is bad for everything. In fact the tropical blue water you see in resort island commercials is due to the water being so nutrient poor that plankton can't thrive.
  7. Oct 2, 2009 #6
    I know little about algae, but what I thought I knew was that algal blooms occur because algae (autotrophs) out-reproduce algae-eaters (heterotrophs). So, in a higher latitude, the difference of metabolic rates between the two grow pretty large (even if they're the same mass), due to the fact that the activation energies for the autotrophs are lower.

    I don't know how the role of nutrients play in all this. But wouldn't CO2 be sufficiently abundent anywhere? That is, is there a difference in the CO2 abundance in the bering sea vs the south pacific? Are heterotrophs required for autotrophs to be present in the sea?
  8. Oct 2, 2009 #7
    1) If it was a matter of algae reproducing quicker than algae eaters, the equilibrium would be shifted in favor of the algae eaters, since they're in a very abundant food source. Since this isn't the case, one knows that that isn't what's going on.

    2) Metabolic rate is controlled by the abundance (or lack, thereof) of nutrients. As you go to higher latitudes, the concentration of nutrients increases, so metabolism will be shifted into higher gear.

    3) Remember that C02 makes up only roughly 1% of the atmosphere, so in a warm area, such as the south pacific, there is a lower CO2 concentration(Charles' Law)- which limits algal growth.

    4) Generally speaking, yes heterotrophs are required for a sustained growth of algae. This is because when an algal bloom emerges, much of the atmospheric CO2 is consumed just because of the sheer number of algae. With this said, I'll concede that the CO2 cycle isn't completely fueled by heterotrophs as there ARE abiotic sources of CO2, though these abiotic sources (volcanism, deep sea vents, chemical conversion of carbonates (only in high pH water, etc) aren't nearly enough to sustain algal growth throughout a bloom.
  9. Oct 3, 2009 #8

    jim mcnamara

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    Staff: Mentor

    VERY large blooms of phytoplankton (algae) are the norm in cooler waters. This is the basis of the food chain in these areas. They are the result of increased sunlight and nutrient upwelling. They are not an anomaly.

    Satellite images:
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